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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/percpu.c - percpu memory allocator
4 *
5 * Copyright (C) 2009 SUSE Linux Products GmbH
6 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 *
8 * Copyright (C) 2017 Facebook Inc.
9 * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org>
10 *
11 * The percpu allocator handles both static and dynamic areas. Percpu
12 * areas are allocated in chunks which are divided into units. There is
13 * a 1-to-1 mapping for units to possible cpus. These units are grouped
14 * based on NUMA properties of the machine.
15 *
16 * c0 c1 c2
17 * ------------------- ------------------- ------------
18 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
19 * ------------------- ...... ------------------- .... ------------
20 *
21 * Allocation is done by offsets into a unit's address space. Ie., an
22 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
23 * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
24 * and even sparse. Access is handled by configuring percpu base
25 * registers according to the cpu to unit mappings and offsetting the
26 * base address using pcpu_unit_size.
27 *
28 * There is special consideration for the first chunk which must handle
29 * the static percpu variables in the kernel image as allocation services
30 * are not online yet. In short, the first chunk is structured like so:
31 *
32 * <Static | [Reserved] | Dynamic>
33 *
34 * The static data is copied from the original section managed by the
35 * linker. The reserved section, if non-zero, primarily manages static
36 * percpu variables from kernel modules. Finally, the dynamic section
37 * takes care of normal allocations.
38 *
39 * The allocator organizes chunks into lists according to free size and
40 * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
41 * flag should be passed. All memcg-aware allocations are sharing one set
42 * of chunks and all unaccounted allocations and allocations performed
43 * by processes belonging to the root memory cgroup are using the second set.
44 *
45 * The allocator tries to allocate from the fullest chunk first. Each chunk
46 * is managed by a bitmap with metadata blocks. The allocation map is updated
47 * on every allocation and free to reflect the current state while the boundary
48 * map is only updated on allocation. Each metadata block contains
49 * information to help mitigate the need to iterate over large portions
50 * of the bitmap. The reverse mapping from page to chunk is stored in
51 * the page's index. Lastly, units are lazily backed and grow in unison.
52 *
53 * There is a unique conversion that goes on here between bytes and bits.
54 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
55 * tracks the number of pages it is responsible for in nr_pages. Helper
56 * functions are used to convert from between the bytes, bits, and blocks.
57 * All hints are managed in bits unless explicitly stated.
58 *
59 * To use this allocator, arch code should do the following:
60 *
61 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
62 * regular address to percpu pointer and back if they need to be
63 * different from the default
64 *
65 * - use pcpu_setup_first_chunk() during percpu area initialization to
66 * setup the first chunk containing the kernel static percpu area
67 */
68
69#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
70
71#include <linux/bitmap.h>
72#include <linux/memblock.h>
73#include <linux/err.h>
74#include <linux/lcm.h>
75#include <linux/list.h>
76#include <linux/log2.h>
77#include <linux/mm.h>
78#include <linux/module.h>
79#include <linux/mutex.h>
80#include <linux/percpu.h>
81#include <linux/pfn.h>
82#include <linux/slab.h>
83#include <linux/spinlock.h>
84#include <linux/vmalloc.h>
85#include <linux/workqueue.h>
86#include <linux/kmemleak.h>
87#include <linux/sched.h>
88#include <linux/sched/mm.h>
89#include <linux/memcontrol.h>
90
91#include <asm/cacheflush.h>
92#include <asm/sections.h>
93#include <asm/tlbflush.h>
94#include <asm/io.h>
95
96#define CREATE_TRACE_POINTS
97#include <trace/events/percpu.h>
98
99#include "percpu-internal.h"
100
101/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */
102#define PCPU_SLOT_BASE_SHIFT 5
103/* chunks in slots below this are subject to being sidelined on failed alloc */
104#define PCPU_SLOT_FAIL_THRESHOLD 3
105
106#define PCPU_EMPTY_POP_PAGES_LOW 2
107#define PCPU_EMPTY_POP_PAGES_HIGH 4
108
109#ifdef CONFIG_SMP
110/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
111#ifndef __addr_to_pcpu_ptr
112#define __addr_to_pcpu_ptr(addr) \
113 (void __percpu *)((unsigned long)(addr) - \
114 (unsigned long)pcpu_base_addr + \
115 (unsigned long)__per_cpu_start)
116#endif
117#ifndef __pcpu_ptr_to_addr
118#define __pcpu_ptr_to_addr(ptr) \
119 (void __force *)((unsigned long)(ptr) + \
120 (unsigned long)pcpu_base_addr - \
121 (unsigned long)__per_cpu_start)
122#endif
123#else /* CONFIG_SMP */
124/* on UP, it's always identity mapped */
125#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
126#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
127#endif /* CONFIG_SMP */
128
129static int pcpu_unit_pages __ro_after_init;
130static int pcpu_unit_size __ro_after_init;
131static int pcpu_nr_units __ro_after_init;
132static int pcpu_atom_size __ro_after_init;
133int pcpu_nr_slots __ro_after_init;
134static size_t pcpu_chunk_struct_size __ro_after_init;
135
136/* cpus with the lowest and highest unit addresses */
137static unsigned int pcpu_low_unit_cpu __ro_after_init;
138static unsigned int pcpu_high_unit_cpu __ro_after_init;
139
140/* the address of the first chunk which starts with the kernel static area */
141void *pcpu_base_addr __ro_after_init;
142EXPORT_SYMBOL_GPL(pcpu_base_addr);
143
144static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
145const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
146
147/* group information, used for vm allocation */
148static int pcpu_nr_groups __ro_after_init;
149static const unsigned long *pcpu_group_offsets __ro_after_init;
150static const size_t *pcpu_group_sizes __ro_after_init;
151
152/*
153 * The first chunk which always exists. Note that unlike other
154 * chunks, this one can be allocated and mapped in several different
155 * ways and thus often doesn't live in the vmalloc area.
156 */
157struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
158
159/*
160 * Optional reserved chunk. This chunk reserves part of the first
161 * chunk and serves it for reserved allocations. When the reserved
162 * region doesn't exist, the following variable is NULL.
163 */
164struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
165
166DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
167static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
168
169struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
170
171/* chunks which need their map areas extended, protected by pcpu_lock */
172static LIST_HEAD(pcpu_map_extend_chunks);
173
174/*
175 * The number of empty populated pages, protected by pcpu_lock. The
176 * reserved chunk doesn't contribute to the count.
177 */
178int pcpu_nr_empty_pop_pages;
179
180/*
181 * The number of populated pages in use by the allocator, protected by
182 * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets
183 * allocated/deallocated, it is allocated/deallocated in all units of a chunk
184 * and increments/decrements this count by 1).
185 */
186static unsigned long pcpu_nr_populated;
187
188/*
189 * Balance work is used to populate or destroy chunks asynchronously. We
190 * try to keep the number of populated free pages between
191 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
192 * empty chunk.
193 */
194static void pcpu_balance_workfn(struct work_struct *work);
195static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
196static bool pcpu_async_enabled __read_mostly;
197static bool pcpu_atomic_alloc_failed;
198
199static void pcpu_schedule_balance_work(void)
200{
201 if (pcpu_async_enabled)
202 schedule_work(&pcpu_balance_work);
203}
204
205/**
206 * pcpu_addr_in_chunk - check if the address is served from this chunk
207 * @chunk: chunk of interest
208 * @addr: percpu address
209 *
210 * RETURNS:
211 * True if the address is served from this chunk.
212 */
213static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
214{
215 void *start_addr, *end_addr;
216
217 if (!chunk)
218 return false;
219
220 start_addr = chunk->base_addr + chunk->start_offset;
221 end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
222 chunk->end_offset;
223
224 return addr >= start_addr && addr < end_addr;
225}
226
227static int __pcpu_size_to_slot(int size)
228{
229 int highbit = fls(size); /* size is in bytes */
230 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
231}
232
233static int pcpu_size_to_slot(int size)
234{
235 if (size == pcpu_unit_size)
236 return pcpu_nr_slots - 1;
237 return __pcpu_size_to_slot(size);
238}
239
240static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
241{
242 const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
243
244 if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
245 chunk_md->contig_hint == 0)
246 return 0;
247
248 return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
249}
250
251/* set the pointer to a chunk in a page struct */
252static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
253{
254 page->index = (unsigned long)pcpu;
255}
256
257/* obtain pointer to a chunk from a page struct */
258static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
259{
260 return (struct pcpu_chunk *)page->index;
261}
262
263static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
264{
265 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
266}
267
268static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
269{
270 return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
271}
272
273static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
274 unsigned int cpu, int page_idx)
275{
276 return (unsigned long)chunk->base_addr +
277 pcpu_unit_page_offset(cpu, page_idx);
278}
279
280/*
281 * The following are helper functions to help access bitmaps and convert
282 * between bitmap offsets to address offsets.
283 */
284static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
285{
286 return chunk->alloc_map +
287 (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
288}
289
290static unsigned long pcpu_off_to_block_index(int off)
291{
292 return off / PCPU_BITMAP_BLOCK_BITS;
293}
294
295static unsigned long pcpu_off_to_block_off(int off)
296{
297 return off & (PCPU_BITMAP_BLOCK_BITS - 1);
298}
299
300static unsigned long pcpu_block_off_to_off(int index, int off)
301{
302 return index * PCPU_BITMAP_BLOCK_BITS + off;
303}
304
305/*
306 * pcpu_next_hint - determine which hint to use
307 * @block: block of interest
308 * @alloc_bits: size of allocation
309 *
310 * This determines if we should scan based on the scan_hint or first_free.
311 * In general, we want to scan from first_free to fulfill allocations by
312 * first fit. However, if we know a scan_hint at position scan_hint_start
313 * cannot fulfill an allocation, we can begin scanning from there knowing
314 * the contig_hint will be our fallback.
315 */
316static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
317{
318 /*
319 * The three conditions below determine if we can skip past the
320 * scan_hint. First, does the scan hint exist. Second, is the
321 * contig_hint after the scan_hint (possibly not true iff
322 * contig_hint == scan_hint). Third, is the allocation request
323 * larger than the scan_hint.
324 */
325 if (block->scan_hint &&
326 block->contig_hint_start > block->scan_hint_start &&
327 alloc_bits > block->scan_hint)
328 return block->scan_hint_start + block->scan_hint;
329
330 return block->first_free;
331}
332
333/**
334 * pcpu_next_md_free_region - finds the next hint free area
335 * @chunk: chunk of interest
336 * @bit_off: chunk offset
337 * @bits: size of free area
338 *
339 * Helper function for pcpu_for_each_md_free_region. It checks
340 * block->contig_hint and performs aggregation across blocks to find the
341 * next hint. It modifies bit_off and bits in-place to be consumed in the
342 * loop.
343 */
344static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
345 int *bits)
346{
347 int i = pcpu_off_to_block_index(*bit_off);
348 int block_off = pcpu_off_to_block_off(*bit_off);
349 struct pcpu_block_md *block;
350
351 *bits = 0;
352 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
353 block++, i++) {
354 /* handles contig area across blocks */
355 if (*bits) {
356 *bits += block->left_free;
357 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
358 continue;
359 return;
360 }
361
362 /*
363 * This checks three things. First is there a contig_hint to
364 * check. Second, have we checked this hint before by
365 * comparing the block_off. Third, is this the same as the
366 * right contig hint. In the last case, it spills over into
367 * the next block and should be handled by the contig area
368 * across blocks code.
369 */
370 *bits = block->contig_hint;
371 if (*bits && block->contig_hint_start >= block_off &&
372 *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
373 *bit_off = pcpu_block_off_to_off(i,
374 block->contig_hint_start);
375 return;
376 }
377 /* reset to satisfy the second predicate above */
378 block_off = 0;
379
380 *bits = block->right_free;
381 *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
382 }
383}
384
385/**
386 * pcpu_next_fit_region - finds fit areas for a given allocation request
387 * @chunk: chunk of interest
388 * @alloc_bits: size of allocation
389 * @align: alignment of area (max PAGE_SIZE)
390 * @bit_off: chunk offset
391 * @bits: size of free area
392 *
393 * Finds the next free region that is viable for use with a given size and
394 * alignment. This only returns if there is a valid area to be used for this
395 * allocation. block->first_free is returned if the allocation request fits
396 * within the block to see if the request can be fulfilled prior to the contig
397 * hint.
398 */
399static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
400 int align, int *bit_off, int *bits)
401{
402 int i = pcpu_off_to_block_index(*bit_off);
403 int block_off = pcpu_off_to_block_off(*bit_off);
404 struct pcpu_block_md *block;
405
406 *bits = 0;
407 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
408 block++, i++) {
409 /* handles contig area across blocks */
410 if (*bits) {
411 *bits += block->left_free;
412 if (*bits >= alloc_bits)
413 return;
414 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
415 continue;
416 }
417
418 /* check block->contig_hint */
419 *bits = ALIGN(block->contig_hint_start, align) -
420 block->contig_hint_start;
421 /*
422 * This uses the block offset to determine if this has been
423 * checked in the prior iteration.
424 */
425 if (block->contig_hint &&
426 block->contig_hint_start >= block_off &&
427 block->contig_hint >= *bits + alloc_bits) {
428 int start = pcpu_next_hint(block, alloc_bits);
429
430 *bits += alloc_bits + block->contig_hint_start -
431 start;
432 *bit_off = pcpu_block_off_to_off(i, start);
433 return;
434 }
435 /* reset to satisfy the second predicate above */
436 block_off = 0;
437
438 *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
439 align);
440 *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
441 *bit_off = pcpu_block_off_to_off(i, *bit_off);
442 if (*bits >= alloc_bits)
443 return;
444 }
445
446 /* no valid offsets were found - fail condition */
447 *bit_off = pcpu_chunk_map_bits(chunk);
448}
449
450/*
451 * Metadata free area iterators. These perform aggregation of free areas
452 * based on the metadata blocks and return the offset @bit_off and size in
453 * bits of the free area @bits. pcpu_for_each_fit_region only returns when
454 * a fit is found for the allocation request.
455 */
456#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
457 for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
458 (bit_off) < pcpu_chunk_map_bits((chunk)); \
459 (bit_off) += (bits) + 1, \
460 pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
461
462#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
463 for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
464 &(bits)); \
465 (bit_off) < pcpu_chunk_map_bits((chunk)); \
466 (bit_off) += (bits), \
467 pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
468 &(bits)))
469
470/**
471 * pcpu_mem_zalloc - allocate memory
472 * @size: bytes to allocate
473 * @gfp: allocation flags
474 *
475 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
476 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
477 * This is to facilitate passing through whitelisted flags. The
478 * returned memory is always zeroed.
479 *
480 * RETURNS:
481 * Pointer to the allocated area on success, NULL on failure.
482 */
483static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
484{
485 if (WARN_ON_ONCE(!slab_is_available()))
486 return NULL;
487
488 if (size <= PAGE_SIZE)
489 return kzalloc(size, gfp);
490 else
491 return __vmalloc(size, gfp | __GFP_ZERO);
492}
493
494/**
495 * pcpu_mem_free - free memory
496 * @ptr: memory to free
497 *
498 * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
499 */
500static void pcpu_mem_free(void *ptr)
501{
502 kvfree(ptr);
503}
504
505static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
506 bool move_front)
507{
508 if (chunk != pcpu_reserved_chunk) {
509 struct list_head *pcpu_slot;
510
511 pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
512 if (move_front)
513 list_move(&chunk->list, &pcpu_slot[slot]);
514 else
515 list_move_tail(&chunk->list, &pcpu_slot[slot]);
516 }
517}
518
519static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
520{
521 __pcpu_chunk_move(chunk, slot, true);
522}
523
524/**
525 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
526 * @chunk: chunk of interest
527 * @oslot: the previous slot it was on
528 *
529 * This function is called after an allocation or free changed @chunk.
530 * New slot according to the changed state is determined and @chunk is
531 * moved to the slot. Note that the reserved chunk is never put on
532 * chunk slots.
533 *
534 * CONTEXT:
535 * pcpu_lock.
536 */
537static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
538{
539 int nslot = pcpu_chunk_slot(chunk);
540
541 if (oslot != nslot)
542 __pcpu_chunk_move(chunk, nslot, oslot < nslot);
543}
544
545/*
546 * pcpu_update_empty_pages - update empty page counters
547 * @chunk: chunk of interest
548 * @nr: nr of empty pages
549 *
550 * This is used to keep track of the empty pages now based on the premise
551 * a md_block covers a page. The hint update functions recognize if a block
552 * is made full or broken to calculate deltas for keeping track of free pages.
553 */
554static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
555{
556 chunk->nr_empty_pop_pages += nr;
557 if (chunk != pcpu_reserved_chunk)
558 pcpu_nr_empty_pop_pages += nr;
559}
560
561/*
562 * pcpu_region_overlap - determines if two regions overlap
563 * @a: start of first region, inclusive
564 * @b: end of first region, exclusive
565 * @x: start of second region, inclusive
566 * @y: end of second region, exclusive
567 *
568 * This is used to determine if the hint region [a, b) overlaps with the
569 * allocated region [x, y).
570 */
571static inline bool pcpu_region_overlap(int a, int b, int x, int y)
572{
573 return (a < y) && (x < b);
574}
575
576/**
577 * pcpu_block_update - updates a block given a free area
578 * @block: block of interest
579 * @start: start offset in block
580 * @end: end offset in block
581 *
582 * Updates a block given a known free area. The region [start, end) is
583 * expected to be the entirety of the free area within a block. Chooses
584 * the best starting offset if the contig hints are equal.
585 */
586static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
587{
588 int contig = end - start;
589
590 block->first_free = min(block->first_free, start);
591 if (start == 0)
592 block->left_free = contig;
593
594 if (end == block->nr_bits)
595 block->right_free = contig;
596
597 if (contig > block->contig_hint) {
598 /* promote the old contig_hint to be the new scan_hint */
599 if (start > block->contig_hint_start) {
600 if (block->contig_hint > block->scan_hint) {
601 block->scan_hint_start =
602 block->contig_hint_start;
603 block->scan_hint = block->contig_hint;
604 } else if (start < block->scan_hint_start) {
605 /*
606 * The old contig_hint == scan_hint. But, the
607 * new contig is larger so hold the invariant
608 * scan_hint_start < contig_hint_start.
609 */
610 block->scan_hint = 0;
611 }
612 } else {
613 block->scan_hint = 0;
614 }
615 block->contig_hint_start = start;
616 block->contig_hint = contig;
617 } else if (contig == block->contig_hint) {
618 if (block->contig_hint_start &&
619 (!start ||
620 __ffs(start) > __ffs(block->contig_hint_start))) {
621 /* start has a better alignment so use it */
622 block->contig_hint_start = start;
623 if (start < block->scan_hint_start &&
624 block->contig_hint > block->scan_hint)
625 block->scan_hint = 0;
626 } else if (start > block->scan_hint_start ||
627 block->contig_hint > block->scan_hint) {
628 /*
629 * Knowing contig == contig_hint, update the scan_hint
630 * if it is farther than or larger than the current
631 * scan_hint.
632 */
633 block->scan_hint_start = start;
634 block->scan_hint = contig;
635 }
636 } else {
637 /*
638 * The region is smaller than the contig_hint. So only update
639 * the scan_hint if it is larger than or equal and farther than
640 * the current scan_hint.
641 */
642 if ((start < block->contig_hint_start &&
643 (contig > block->scan_hint ||
644 (contig == block->scan_hint &&
645 start > block->scan_hint_start)))) {
646 block->scan_hint_start = start;
647 block->scan_hint = contig;
648 }
649 }
650}
651
652/*
653 * pcpu_block_update_scan - update a block given a free area from a scan
654 * @chunk: chunk of interest
655 * @bit_off: chunk offset
656 * @bits: size of free area
657 *
658 * Finding the final allocation spot first goes through pcpu_find_block_fit()
659 * to find a block that can hold the allocation and then pcpu_alloc_area()
660 * where a scan is used. When allocations require specific alignments,
661 * we can inadvertently create holes which will not be seen in the alloc
662 * or free paths.
663 *
664 * This takes a given free area hole and updates a block as it may change the
665 * scan_hint. We need to scan backwards to ensure we don't miss free bits
666 * from alignment.
667 */
668static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
669 int bits)
670{
671 int s_off = pcpu_off_to_block_off(bit_off);
672 int e_off = s_off + bits;
673 int s_index, l_bit;
674 struct pcpu_block_md *block;
675
676 if (e_off > PCPU_BITMAP_BLOCK_BITS)
677 return;
678
679 s_index = pcpu_off_to_block_index(bit_off);
680 block = chunk->md_blocks + s_index;
681
682 /* scan backwards in case of alignment skipping free bits */
683 l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
684 s_off = (s_off == l_bit) ? 0 : l_bit + 1;
685
686 pcpu_block_update(block, s_off, e_off);
687}
688
689/**
690 * pcpu_chunk_refresh_hint - updates metadata about a chunk
691 * @chunk: chunk of interest
692 * @full_scan: if we should scan from the beginning
693 *
694 * Iterates over the metadata blocks to find the largest contig area.
695 * A full scan can be avoided on the allocation path as this is triggered
696 * if we broke the contig_hint. In doing so, the scan_hint will be before
697 * the contig_hint or after if the scan_hint == contig_hint. This cannot
698 * be prevented on freeing as we want to find the largest area possibly
699 * spanning blocks.
700 */
701static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
702{
703 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
704 int bit_off, bits;
705
706 /* promote scan_hint to contig_hint */
707 if (!full_scan && chunk_md->scan_hint) {
708 bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
709 chunk_md->contig_hint_start = chunk_md->scan_hint_start;
710 chunk_md->contig_hint = chunk_md->scan_hint;
711 chunk_md->scan_hint = 0;
712 } else {
713 bit_off = chunk_md->first_free;
714 chunk_md->contig_hint = 0;
715 }
716
717 bits = 0;
718 pcpu_for_each_md_free_region(chunk, bit_off, bits)
719 pcpu_block_update(chunk_md, bit_off, bit_off + bits);
720}
721
722/**
723 * pcpu_block_refresh_hint
724 * @chunk: chunk of interest
725 * @index: index of the metadata block
726 *
727 * Scans over the block beginning at first_free and updates the block
728 * metadata accordingly.
729 */
730static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
731{
732 struct pcpu_block_md *block = chunk->md_blocks + index;
733 unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
734 unsigned int rs, re, start; /* region start, region end */
735
736 /* promote scan_hint to contig_hint */
737 if (block->scan_hint) {
738 start = block->scan_hint_start + block->scan_hint;
739 block->contig_hint_start = block->scan_hint_start;
740 block->contig_hint = block->scan_hint;
741 block->scan_hint = 0;
742 } else {
743 start = block->first_free;
744 block->contig_hint = 0;
745 }
746
747 block->right_free = 0;
748
749 /* iterate over free areas and update the contig hints */
750 bitmap_for_each_clear_region(alloc_map, rs, re, start,
751 PCPU_BITMAP_BLOCK_BITS)
752 pcpu_block_update(block, rs, re);
753}
754
755/**
756 * pcpu_block_update_hint_alloc - update hint on allocation path
757 * @chunk: chunk of interest
758 * @bit_off: chunk offset
759 * @bits: size of request
760 *
761 * Updates metadata for the allocation path. The metadata only has to be
762 * refreshed by a full scan iff the chunk's contig hint is broken. Block level
763 * scans are required if the block's contig hint is broken.
764 */
765static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
766 int bits)
767{
768 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
769 int nr_empty_pages = 0;
770 struct pcpu_block_md *s_block, *e_block, *block;
771 int s_index, e_index; /* block indexes of the freed allocation */
772 int s_off, e_off; /* block offsets of the freed allocation */
773
774 /*
775 * Calculate per block offsets.
776 * The calculation uses an inclusive range, but the resulting offsets
777 * are [start, end). e_index always points to the last block in the
778 * range.
779 */
780 s_index = pcpu_off_to_block_index(bit_off);
781 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
782 s_off = pcpu_off_to_block_off(bit_off);
783 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
784
785 s_block = chunk->md_blocks + s_index;
786 e_block = chunk->md_blocks + e_index;
787
788 /*
789 * Update s_block.
790 * block->first_free must be updated if the allocation takes its place.
791 * If the allocation breaks the contig_hint, a scan is required to
792 * restore this hint.
793 */
794 if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
795 nr_empty_pages++;
796
797 if (s_off == s_block->first_free)
798 s_block->first_free = find_next_zero_bit(
799 pcpu_index_alloc_map(chunk, s_index),
800 PCPU_BITMAP_BLOCK_BITS,
801 s_off + bits);
802
803 if (pcpu_region_overlap(s_block->scan_hint_start,
804 s_block->scan_hint_start + s_block->scan_hint,
805 s_off,
806 s_off + bits))
807 s_block->scan_hint = 0;
808
809 if (pcpu_region_overlap(s_block->contig_hint_start,
810 s_block->contig_hint_start +
811 s_block->contig_hint,
812 s_off,
813 s_off + bits)) {
814 /* block contig hint is broken - scan to fix it */
815 if (!s_off)
816 s_block->left_free = 0;
817 pcpu_block_refresh_hint(chunk, s_index);
818 } else {
819 /* update left and right contig manually */
820 s_block->left_free = min(s_block->left_free, s_off);
821 if (s_index == e_index)
822 s_block->right_free = min_t(int, s_block->right_free,
823 PCPU_BITMAP_BLOCK_BITS - e_off);
824 else
825 s_block->right_free = 0;
826 }
827
828 /*
829 * Update e_block.
830 */
831 if (s_index != e_index) {
832 if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
833 nr_empty_pages++;
834
835 /*
836 * When the allocation is across blocks, the end is along
837 * the left part of the e_block.
838 */
839 e_block->first_free = find_next_zero_bit(
840 pcpu_index_alloc_map(chunk, e_index),
841 PCPU_BITMAP_BLOCK_BITS, e_off);
842
843 if (e_off == PCPU_BITMAP_BLOCK_BITS) {
844 /* reset the block */
845 e_block++;
846 } else {
847 if (e_off > e_block->scan_hint_start)
848 e_block->scan_hint = 0;
849
850 e_block->left_free = 0;
851 if (e_off > e_block->contig_hint_start) {
852 /* contig hint is broken - scan to fix it */
853 pcpu_block_refresh_hint(chunk, e_index);
854 } else {
855 e_block->right_free =
856 min_t(int, e_block->right_free,
857 PCPU_BITMAP_BLOCK_BITS - e_off);
858 }
859 }
860
861 /* update in-between md_blocks */
862 nr_empty_pages += (e_index - s_index - 1);
863 for (block = s_block + 1; block < e_block; block++) {
864 block->scan_hint = 0;
865 block->contig_hint = 0;
866 block->left_free = 0;
867 block->right_free = 0;
868 }
869 }
870
871 if (nr_empty_pages)
872 pcpu_update_empty_pages(chunk, -nr_empty_pages);
873
874 if (pcpu_region_overlap(chunk_md->scan_hint_start,
875 chunk_md->scan_hint_start +
876 chunk_md->scan_hint,
877 bit_off,
878 bit_off + bits))
879 chunk_md->scan_hint = 0;
880
881 /*
882 * The only time a full chunk scan is required is if the chunk
883 * contig hint is broken. Otherwise, it means a smaller space
884 * was used and therefore the chunk contig hint is still correct.
885 */
886 if (pcpu_region_overlap(chunk_md->contig_hint_start,
887 chunk_md->contig_hint_start +
888 chunk_md->contig_hint,
889 bit_off,
890 bit_off + bits))
891 pcpu_chunk_refresh_hint(chunk, false);
892}
893
894/**
895 * pcpu_block_update_hint_free - updates the block hints on the free path
896 * @chunk: chunk of interest
897 * @bit_off: chunk offset
898 * @bits: size of request
899 *
900 * Updates metadata for the allocation path. This avoids a blind block
901 * refresh by making use of the block contig hints. If this fails, it scans
902 * forward and backward to determine the extent of the free area. This is
903 * capped at the boundary of blocks.
904 *
905 * A chunk update is triggered if a page becomes free, a block becomes free,
906 * or the free spans across blocks. This tradeoff is to minimize iterating
907 * over the block metadata to update chunk_md->contig_hint.
908 * chunk_md->contig_hint may be off by up to a page, but it will never be more
909 * than the available space. If the contig hint is contained in one block, it
910 * will be accurate.
911 */
912static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
913 int bits)
914{
915 int nr_empty_pages = 0;
916 struct pcpu_block_md *s_block, *e_block, *block;
917 int s_index, e_index; /* block indexes of the freed allocation */
918 int s_off, e_off; /* block offsets of the freed allocation */
919 int start, end; /* start and end of the whole free area */
920
921 /*
922 * Calculate per block offsets.
923 * The calculation uses an inclusive range, but the resulting offsets
924 * are [start, end). e_index always points to the last block in the
925 * range.
926 */
927 s_index = pcpu_off_to_block_index(bit_off);
928 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
929 s_off = pcpu_off_to_block_off(bit_off);
930 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
931
932 s_block = chunk->md_blocks + s_index;
933 e_block = chunk->md_blocks + e_index;
934
935 /*
936 * Check if the freed area aligns with the block->contig_hint.
937 * If it does, then the scan to find the beginning/end of the
938 * larger free area can be avoided.
939 *
940 * start and end refer to beginning and end of the free area
941 * within each their respective blocks. This is not necessarily
942 * the entire free area as it may span blocks past the beginning
943 * or end of the block.
944 */
945 start = s_off;
946 if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
947 start = s_block->contig_hint_start;
948 } else {
949 /*
950 * Scan backwards to find the extent of the free area.
951 * find_last_bit returns the starting bit, so if the start bit
952 * is returned, that means there was no last bit and the
953 * remainder of the chunk is free.
954 */
955 int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
956 start);
957 start = (start == l_bit) ? 0 : l_bit + 1;
958 }
959
960 end = e_off;
961 if (e_off == e_block->contig_hint_start)
962 end = e_block->contig_hint_start + e_block->contig_hint;
963 else
964 end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
965 PCPU_BITMAP_BLOCK_BITS, end);
966
967 /* update s_block */
968 e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
969 if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
970 nr_empty_pages++;
971 pcpu_block_update(s_block, start, e_off);
972
973 /* freeing in the same block */
974 if (s_index != e_index) {
975 /* update e_block */
976 if (end == PCPU_BITMAP_BLOCK_BITS)
977 nr_empty_pages++;
978 pcpu_block_update(e_block, 0, end);
979
980 /* reset md_blocks in the middle */
981 nr_empty_pages += (e_index - s_index - 1);
982 for (block = s_block + 1; block < e_block; block++) {
983 block->first_free = 0;
984 block->scan_hint = 0;
985 block->contig_hint_start = 0;
986 block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
987 block->left_free = PCPU_BITMAP_BLOCK_BITS;
988 block->right_free = PCPU_BITMAP_BLOCK_BITS;
989 }
990 }
991
992 if (nr_empty_pages)
993 pcpu_update_empty_pages(chunk, nr_empty_pages);
994
995 /*
996 * Refresh chunk metadata when the free makes a block free or spans
997 * across blocks. The contig_hint may be off by up to a page, but if
998 * the contig_hint is contained in a block, it will be accurate with
999 * the else condition below.
1000 */
1001 if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1002 pcpu_chunk_refresh_hint(chunk, true);
1003 else
1004 pcpu_block_update(&chunk->chunk_md,
1005 pcpu_block_off_to_off(s_index, start),
1006 end);
1007}
1008
1009/**
1010 * pcpu_is_populated - determines if the region is populated
1011 * @chunk: chunk of interest
1012 * @bit_off: chunk offset
1013 * @bits: size of area
1014 * @next_off: return value for the next offset to start searching
1015 *
1016 * For atomic allocations, check if the backing pages are populated.
1017 *
1018 * RETURNS:
1019 * Bool if the backing pages are populated.
1020 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1021 */
1022static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1023 int *next_off)
1024{
1025 unsigned int page_start, page_end, rs, re;
1026
1027 page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1028 page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1029
1030 rs = page_start;
1031 bitmap_next_clear_region(chunk->populated, &rs, &re, page_end);
1032 if (rs >= page_end)
1033 return true;
1034
1035 *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1036 return false;
1037}
1038
1039/**
1040 * pcpu_find_block_fit - finds the block index to start searching
1041 * @chunk: chunk of interest
1042 * @alloc_bits: size of request in allocation units
1043 * @align: alignment of area (max PAGE_SIZE bytes)
1044 * @pop_only: use populated regions only
1045 *
1046 * Given a chunk and an allocation spec, find the offset to begin searching
1047 * for a free region. This iterates over the bitmap metadata blocks to
1048 * find an offset that will be guaranteed to fit the requirements. It is
1049 * not quite first fit as if the allocation does not fit in the contig hint
1050 * of a block or chunk, it is skipped. This errs on the side of caution
1051 * to prevent excess iteration. Poor alignment can cause the allocator to
1052 * skip over blocks and chunks that have valid free areas.
1053 *
1054 * RETURNS:
1055 * The offset in the bitmap to begin searching.
1056 * -1 if no offset is found.
1057 */
1058static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1059 size_t align, bool pop_only)
1060{
1061 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1062 int bit_off, bits, next_off;
1063
1064 /*
1065 * Check to see if the allocation can fit in the chunk's contig hint.
1066 * This is an optimization to prevent scanning by assuming if it
1067 * cannot fit in the global hint, there is memory pressure and creating
1068 * a new chunk would happen soon.
1069 */
1070 bit_off = ALIGN(chunk_md->contig_hint_start, align) -
1071 chunk_md->contig_hint_start;
1072 if (bit_off + alloc_bits > chunk_md->contig_hint)
1073 return -1;
1074
1075 bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1076 bits = 0;
1077 pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1078 if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1079 &next_off))
1080 break;
1081
1082 bit_off = next_off;
1083 bits = 0;
1084 }
1085
1086 if (bit_off == pcpu_chunk_map_bits(chunk))
1087 return -1;
1088
1089 return bit_off;
1090}
1091
1092/*
1093 * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1094 * @map: the address to base the search on
1095 * @size: the bitmap size in bits
1096 * @start: the bitnumber to start searching at
1097 * @nr: the number of zeroed bits we're looking for
1098 * @align_mask: alignment mask for zero area
1099 * @largest_off: offset of the largest area skipped
1100 * @largest_bits: size of the largest area skipped
1101 *
1102 * The @align_mask should be one less than a power of 2.
1103 *
1104 * This is a modified version of bitmap_find_next_zero_area_off() to remember
1105 * the largest area that was skipped. This is imperfect, but in general is
1106 * good enough. The largest remembered region is the largest failed region
1107 * seen. This does not include anything we possibly skipped due to alignment.
1108 * pcpu_block_update_scan() does scan backwards to try and recover what was
1109 * lost to alignment. While this can cause scanning to miss earlier possible
1110 * free areas, smaller allocations will eventually fill those holes.
1111 */
1112static unsigned long pcpu_find_zero_area(unsigned long *map,
1113 unsigned long size,
1114 unsigned long start,
1115 unsigned long nr,
1116 unsigned long align_mask,
1117 unsigned long *largest_off,
1118 unsigned long *largest_bits)
1119{
1120 unsigned long index, end, i, area_off, area_bits;
1121again:
1122 index = find_next_zero_bit(map, size, start);
1123
1124 /* Align allocation */
1125 index = __ALIGN_MASK(index, align_mask);
1126 area_off = index;
1127
1128 end = index + nr;
1129 if (end > size)
1130 return end;
1131 i = find_next_bit(map, end, index);
1132 if (i < end) {
1133 area_bits = i - area_off;
1134 /* remember largest unused area with best alignment */
1135 if (area_bits > *largest_bits ||
1136 (area_bits == *largest_bits && *largest_off &&
1137 (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1138 *largest_off = area_off;
1139 *largest_bits = area_bits;
1140 }
1141
1142 start = i + 1;
1143 goto again;
1144 }
1145 return index;
1146}
1147
1148/**
1149 * pcpu_alloc_area - allocates an area from a pcpu_chunk
1150 * @chunk: chunk of interest
1151 * @alloc_bits: size of request in allocation units
1152 * @align: alignment of area (max PAGE_SIZE)
1153 * @start: bit_off to start searching
1154 *
1155 * This function takes in a @start offset to begin searching to fit an
1156 * allocation of @alloc_bits with alignment @align. It needs to scan
1157 * the allocation map because if it fits within the block's contig hint,
1158 * @start will be block->first_free. This is an attempt to fill the
1159 * allocation prior to breaking the contig hint. The allocation and
1160 * boundary maps are updated accordingly if it confirms a valid
1161 * free area.
1162 *
1163 * RETURNS:
1164 * Allocated addr offset in @chunk on success.
1165 * -1 if no matching area is found.
1166 */
1167static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1168 size_t align, int start)
1169{
1170 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1171 size_t align_mask = (align) ? (align - 1) : 0;
1172 unsigned long area_off = 0, area_bits = 0;
1173 int bit_off, end, oslot;
1174
1175 lockdep_assert_held(&pcpu_lock);
1176
1177 oslot = pcpu_chunk_slot(chunk);
1178
1179 /*
1180 * Search to find a fit.
1181 */
1182 end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1183 pcpu_chunk_map_bits(chunk));
1184 bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1185 align_mask, &area_off, &area_bits);
1186 if (bit_off >= end)
1187 return -1;
1188
1189 if (area_bits)
1190 pcpu_block_update_scan(chunk, area_off, area_bits);
1191
1192 /* update alloc map */
1193 bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1194
1195 /* update boundary map */
1196 set_bit(bit_off, chunk->bound_map);
1197 bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1198 set_bit(bit_off + alloc_bits, chunk->bound_map);
1199
1200 chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1201
1202 /* update first free bit */
1203 if (bit_off == chunk_md->first_free)
1204 chunk_md->first_free = find_next_zero_bit(
1205 chunk->alloc_map,
1206 pcpu_chunk_map_bits(chunk),
1207 bit_off + alloc_bits);
1208
1209 pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1210
1211 pcpu_chunk_relocate(chunk, oslot);
1212
1213 return bit_off * PCPU_MIN_ALLOC_SIZE;
1214}
1215
1216/**
1217 * pcpu_free_area - frees the corresponding offset
1218 * @chunk: chunk of interest
1219 * @off: addr offset into chunk
1220 *
1221 * This function determines the size of an allocation to free using
1222 * the boundary bitmap and clears the allocation map.
1223 *
1224 * RETURNS:
1225 * Number of freed bytes.
1226 */
1227static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
1228{
1229 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1230 int bit_off, bits, end, oslot, freed;
1231
1232 lockdep_assert_held(&pcpu_lock);
1233 pcpu_stats_area_dealloc(chunk);
1234
1235 oslot = pcpu_chunk_slot(chunk);
1236
1237 bit_off = off / PCPU_MIN_ALLOC_SIZE;
1238
1239 /* find end index */
1240 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1241 bit_off + 1);
1242 bits = end - bit_off;
1243 bitmap_clear(chunk->alloc_map, bit_off, bits);
1244
1245 freed = bits * PCPU_MIN_ALLOC_SIZE;
1246
1247 /* update metadata */
1248 chunk->free_bytes += freed;
1249
1250 /* update first free bit */
1251 chunk_md->first_free = min(chunk_md->first_free, bit_off);
1252
1253 pcpu_block_update_hint_free(chunk, bit_off, bits);
1254
1255 pcpu_chunk_relocate(chunk, oslot);
1256
1257 return freed;
1258}
1259
1260static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1261{
1262 block->scan_hint = 0;
1263 block->contig_hint = nr_bits;
1264 block->left_free = nr_bits;
1265 block->right_free = nr_bits;
1266 block->first_free = 0;
1267 block->nr_bits = nr_bits;
1268}
1269
1270static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1271{
1272 struct pcpu_block_md *md_block;
1273
1274 /* init the chunk's block */
1275 pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1276
1277 for (md_block = chunk->md_blocks;
1278 md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1279 md_block++)
1280 pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1281}
1282
1283/**
1284 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1285 * @tmp_addr: the start of the region served
1286 * @map_size: size of the region served
1287 *
1288 * This is responsible for creating the chunks that serve the first chunk. The
1289 * base_addr is page aligned down of @tmp_addr while the region end is page
1290 * aligned up. Offsets are kept track of to determine the region served. All
1291 * this is done to appease the bitmap allocator in avoiding partial blocks.
1292 *
1293 * RETURNS:
1294 * Chunk serving the region at @tmp_addr of @map_size.
1295 */
1296static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1297 int map_size)
1298{
1299 struct pcpu_chunk *chunk;
1300 unsigned long aligned_addr, lcm_align;
1301 int start_offset, offset_bits, region_size, region_bits;
1302 size_t alloc_size;
1303
1304 /* region calculations */
1305 aligned_addr = tmp_addr & PAGE_MASK;
1306
1307 start_offset = tmp_addr - aligned_addr;
1308
1309 /*
1310 * Align the end of the region with the LCM of PAGE_SIZE and
1311 * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of
1312 * the other.
1313 */
1314 lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
1315 region_size = ALIGN(start_offset + map_size, lcm_align);
1316
1317 /* allocate chunk */
1318 alloc_size = sizeof(struct pcpu_chunk) +
1319 BITS_TO_LONGS(region_size >> PAGE_SHIFT) * sizeof(unsigned long);
1320 chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1321 if (!chunk)
1322 panic("%s: Failed to allocate %zu bytes\n", __func__,
1323 alloc_size);
1324
1325 INIT_LIST_HEAD(&chunk->list);
1326
1327 chunk->base_addr = (void *)aligned_addr;
1328 chunk->start_offset = start_offset;
1329 chunk->end_offset = region_size - chunk->start_offset - map_size;
1330
1331 chunk->nr_pages = region_size >> PAGE_SHIFT;
1332 region_bits = pcpu_chunk_map_bits(chunk);
1333
1334 alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1335 chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1336 if (!chunk->alloc_map)
1337 panic("%s: Failed to allocate %zu bytes\n", __func__,
1338 alloc_size);
1339
1340 alloc_size =
1341 BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1342 chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1343 if (!chunk->bound_map)
1344 panic("%s: Failed to allocate %zu bytes\n", __func__,
1345 alloc_size);
1346
1347 alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1348 chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1349 if (!chunk->md_blocks)
1350 panic("%s: Failed to allocate %zu bytes\n", __func__,
1351 alloc_size);
1352
1353#ifdef CONFIG_MEMCG_KMEM
1354 /* first chunk isn't memcg-aware */
1355 chunk->obj_cgroups = NULL;
1356#endif
1357 pcpu_init_md_blocks(chunk);
1358
1359 /* manage populated page bitmap */
1360 chunk->immutable = true;
1361 bitmap_fill(chunk->populated, chunk->nr_pages);
1362 chunk->nr_populated = chunk->nr_pages;
1363 chunk->nr_empty_pop_pages = chunk->nr_pages;
1364
1365 chunk->free_bytes = map_size;
1366
1367 if (chunk->start_offset) {
1368 /* hide the beginning of the bitmap */
1369 offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1370 bitmap_set(chunk->alloc_map, 0, offset_bits);
1371 set_bit(0, chunk->bound_map);
1372 set_bit(offset_bits, chunk->bound_map);
1373
1374 chunk->chunk_md.first_free = offset_bits;
1375
1376 pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1377 }
1378
1379 if (chunk->end_offset) {
1380 /* hide the end of the bitmap */
1381 offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1382 bitmap_set(chunk->alloc_map,
1383 pcpu_chunk_map_bits(chunk) - offset_bits,
1384 offset_bits);
1385 set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1386 chunk->bound_map);
1387 set_bit(region_bits, chunk->bound_map);
1388
1389 pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1390 - offset_bits, offset_bits);
1391 }
1392
1393 return chunk;
1394}
1395
1396static struct pcpu_chunk *pcpu_alloc_chunk(enum pcpu_chunk_type type, gfp_t gfp)
1397{
1398 struct pcpu_chunk *chunk;
1399 int region_bits;
1400
1401 chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1402 if (!chunk)
1403 return NULL;
1404
1405 INIT_LIST_HEAD(&chunk->list);
1406 chunk->nr_pages = pcpu_unit_pages;
1407 region_bits = pcpu_chunk_map_bits(chunk);
1408
1409 chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1410 sizeof(chunk->alloc_map[0]), gfp);
1411 if (!chunk->alloc_map)
1412 goto alloc_map_fail;
1413
1414 chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1415 sizeof(chunk->bound_map[0]), gfp);
1416 if (!chunk->bound_map)
1417 goto bound_map_fail;
1418
1419 chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1420 sizeof(chunk->md_blocks[0]), gfp);
1421 if (!chunk->md_blocks)
1422 goto md_blocks_fail;
1423
1424#ifdef CONFIG_MEMCG_KMEM
1425 if (pcpu_is_memcg_chunk(type)) {
1426 chunk->obj_cgroups =
1427 pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
1428 sizeof(struct obj_cgroup *), gfp);
1429 if (!chunk->obj_cgroups)
1430 goto objcg_fail;
1431 }
1432#endif
1433
1434 pcpu_init_md_blocks(chunk);
1435
1436 /* init metadata */
1437 chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1438
1439 return chunk;
1440
1441#ifdef CONFIG_MEMCG_KMEM
1442objcg_fail:
1443 pcpu_mem_free(chunk->md_blocks);
1444#endif
1445md_blocks_fail:
1446 pcpu_mem_free(chunk->bound_map);
1447bound_map_fail:
1448 pcpu_mem_free(chunk->alloc_map);
1449alloc_map_fail:
1450 pcpu_mem_free(chunk);
1451
1452 return NULL;
1453}
1454
1455static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1456{
1457 if (!chunk)
1458 return;
1459#ifdef CONFIG_MEMCG_KMEM
1460 pcpu_mem_free(chunk->obj_cgroups);
1461#endif
1462 pcpu_mem_free(chunk->md_blocks);
1463 pcpu_mem_free(chunk->bound_map);
1464 pcpu_mem_free(chunk->alloc_map);
1465 pcpu_mem_free(chunk);
1466}
1467
1468/**
1469 * pcpu_chunk_populated - post-population bookkeeping
1470 * @chunk: pcpu_chunk which got populated
1471 * @page_start: the start page
1472 * @page_end: the end page
1473 *
1474 * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1475 * the bookkeeping information accordingly. Must be called after each
1476 * successful population.
1477 *
1478 * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it
1479 * is to serve an allocation in that area.
1480 */
1481static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1482 int page_end)
1483{
1484 int nr = page_end - page_start;
1485
1486 lockdep_assert_held(&pcpu_lock);
1487
1488 bitmap_set(chunk->populated, page_start, nr);
1489 chunk->nr_populated += nr;
1490 pcpu_nr_populated += nr;
1491
1492 pcpu_update_empty_pages(chunk, nr);
1493}
1494
1495/**
1496 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1497 * @chunk: pcpu_chunk which got depopulated
1498 * @page_start: the start page
1499 * @page_end: the end page
1500 *
1501 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1502 * Update the bookkeeping information accordingly. Must be called after
1503 * each successful depopulation.
1504 */
1505static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1506 int page_start, int page_end)
1507{
1508 int nr = page_end - page_start;
1509
1510 lockdep_assert_held(&pcpu_lock);
1511
1512 bitmap_clear(chunk->populated, page_start, nr);
1513 chunk->nr_populated -= nr;
1514 pcpu_nr_populated -= nr;
1515
1516 pcpu_update_empty_pages(chunk, -nr);
1517}
1518
1519/*
1520 * Chunk management implementation.
1521 *
1522 * To allow different implementations, chunk alloc/free and
1523 * [de]population are implemented in a separate file which is pulled
1524 * into this file and compiled together. The following functions
1525 * should be implemented.
1526 *
1527 * pcpu_populate_chunk - populate the specified range of a chunk
1528 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1529 * pcpu_create_chunk - create a new chunk
1530 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1531 * pcpu_addr_to_page - translate address to physical address
1532 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1533 */
1534static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1535 int page_start, int page_end, gfp_t gfp);
1536static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1537 int page_start, int page_end);
1538static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
1539 gfp_t gfp);
1540static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1541static struct page *pcpu_addr_to_page(void *addr);
1542static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1543
1544#ifdef CONFIG_NEED_PER_CPU_KM
1545#include "percpu-km.c"
1546#else
1547#include "percpu-vm.c"
1548#endif
1549
1550/**
1551 * pcpu_chunk_addr_search - determine chunk containing specified address
1552 * @addr: address for which the chunk needs to be determined.
1553 *
1554 * This is an internal function that handles all but static allocations.
1555 * Static percpu address values should never be passed into the allocator.
1556 *
1557 * RETURNS:
1558 * The address of the found chunk.
1559 */
1560static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1561{
1562 /* is it in the dynamic region (first chunk)? */
1563 if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1564 return pcpu_first_chunk;
1565
1566 /* is it in the reserved region? */
1567 if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1568 return pcpu_reserved_chunk;
1569
1570 /*
1571 * The address is relative to unit0 which might be unused and
1572 * thus unmapped. Offset the address to the unit space of the
1573 * current processor before looking it up in the vmalloc
1574 * space. Note that any possible cpu id can be used here, so
1575 * there's no need to worry about preemption or cpu hotplug.
1576 */
1577 addr += pcpu_unit_offsets[raw_smp_processor_id()];
1578 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1579}
1580
1581#ifdef CONFIG_MEMCG_KMEM
1582static enum pcpu_chunk_type pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
1583 struct obj_cgroup **objcgp)
1584{
1585 struct obj_cgroup *objcg;
1586
1587 if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT) ||
1588 memcg_kmem_bypass())
1589 return PCPU_CHUNK_ROOT;
1590
1591 objcg = get_obj_cgroup_from_current();
1592 if (!objcg)
1593 return PCPU_CHUNK_ROOT;
1594
1595 if (obj_cgroup_charge(objcg, gfp, size * num_possible_cpus())) {
1596 obj_cgroup_put(objcg);
1597 return PCPU_FAIL_ALLOC;
1598 }
1599
1600 *objcgp = objcg;
1601 return PCPU_CHUNK_MEMCG;
1602}
1603
1604static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1605 struct pcpu_chunk *chunk, int off,
1606 size_t size)
1607{
1608 if (!objcg)
1609 return;
1610
1611 if (chunk) {
1612 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
1613
1614 rcu_read_lock();
1615 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1616 size * num_possible_cpus());
1617 rcu_read_unlock();
1618 } else {
1619 obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1620 obj_cgroup_put(objcg);
1621 }
1622}
1623
1624static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1625{
1626 struct obj_cgroup *objcg;
1627
1628 if (!pcpu_is_memcg_chunk(pcpu_chunk_type(chunk)))
1629 return;
1630
1631 objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
1632 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
1633
1634 obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1635
1636 rcu_read_lock();
1637 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1638 -(size * num_possible_cpus()));
1639 rcu_read_unlock();
1640
1641 obj_cgroup_put(objcg);
1642}
1643
1644#else /* CONFIG_MEMCG_KMEM */
1645static enum pcpu_chunk_type
1646pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
1647{
1648 return PCPU_CHUNK_ROOT;
1649}
1650
1651static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1652 struct pcpu_chunk *chunk, int off,
1653 size_t size)
1654{
1655}
1656
1657static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1658{
1659}
1660#endif /* CONFIG_MEMCG_KMEM */
1661
1662/**
1663 * pcpu_alloc - the percpu allocator
1664 * @size: size of area to allocate in bytes
1665 * @align: alignment of area (max PAGE_SIZE)
1666 * @reserved: allocate from the reserved chunk if available
1667 * @gfp: allocation flags
1668 *
1669 * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1670 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1671 * then no warning will be triggered on invalid or failed allocation
1672 * requests.
1673 *
1674 * RETURNS:
1675 * Percpu pointer to the allocated area on success, NULL on failure.
1676 */
1677static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1678 gfp_t gfp)
1679{
1680 gfp_t pcpu_gfp;
1681 bool is_atomic;
1682 bool do_warn;
1683 enum pcpu_chunk_type type;
1684 struct list_head *pcpu_slot;
1685 struct obj_cgroup *objcg = NULL;
1686 static int warn_limit = 10;
1687 struct pcpu_chunk *chunk, *next;
1688 const char *err;
1689 int slot, off, cpu, ret;
1690 unsigned long flags;
1691 void __percpu *ptr;
1692 size_t bits, bit_align;
1693
1694 gfp = current_gfp_context(gfp);
1695 /* whitelisted flags that can be passed to the backing allocators */
1696 pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1697 is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1698 do_warn = !(gfp & __GFP_NOWARN);
1699
1700 /*
1701 * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1702 * therefore alignment must be a minimum of that many bytes.
1703 * An allocation may have internal fragmentation from rounding up
1704 * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1705 */
1706 if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1707 align = PCPU_MIN_ALLOC_SIZE;
1708
1709 size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1710 bits = size >> PCPU_MIN_ALLOC_SHIFT;
1711 bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1712
1713 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1714 !is_power_of_2(align))) {
1715 WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1716 size, align);
1717 return NULL;
1718 }
1719
1720 type = pcpu_memcg_pre_alloc_hook(size, gfp, &objcg);
1721 if (unlikely(type == PCPU_FAIL_ALLOC))
1722 return NULL;
1723 pcpu_slot = pcpu_chunk_list(type);
1724
1725 if (!is_atomic) {
1726 /*
1727 * pcpu_balance_workfn() allocates memory under this mutex,
1728 * and it may wait for memory reclaim. Allow current task
1729 * to become OOM victim, in case of memory pressure.
1730 */
1731 if (gfp & __GFP_NOFAIL) {
1732 mutex_lock(&pcpu_alloc_mutex);
1733 } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
1734 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1735 return NULL;
1736 }
1737 }
1738
1739 spin_lock_irqsave(&pcpu_lock, flags);
1740
1741 /* serve reserved allocations from the reserved chunk if available */
1742 if (reserved && pcpu_reserved_chunk) {
1743 chunk = pcpu_reserved_chunk;
1744
1745 off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1746 if (off < 0) {
1747 err = "alloc from reserved chunk failed";
1748 goto fail_unlock;
1749 }
1750
1751 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1752 if (off >= 0)
1753 goto area_found;
1754
1755 err = "alloc from reserved chunk failed";
1756 goto fail_unlock;
1757 }
1758
1759restart:
1760 /* search through normal chunks */
1761 for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
1762 list_for_each_entry_safe(chunk, next, &pcpu_slot[slot], list) {
1763 off = pcpu_find_block_fit(chunk, bits, bit_align,
1764 is_atomic);
1765 if (off < 0) {
1766 if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1767 pcpu_chunk_move(chunk, 0);
1768 continue;
1769 }
1770
1771 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1772 if (off >= 0)
1773 goto area_found;
1774
1775 }
1776 }
1777
1778 spin_unlock_irqrestore(&pcpu_lock, flags);
1779
1780 /*
1781 * No space left. Create a new chunk. We don't want multiple
1782 * tasks to create chunks simultaneously. Serialize and create iff
1783 * there's still no empty chunk after grabbing the mutex.
1784 */
1785 if (is_atomic) {
1786 err = "atomic alloc failed, no space left";
1787 goto fail;
1788 }
1789
1790 if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
1791 chunk = pcpu_create_chunk(type, pcpu_gfp);
1792 if (!chunk) {
1793 err = "failed to allocate new chunk";
1794 goto fail;
1795 }
1796
1797 spin_lock_irqsave(&pcpu_lock, flags);
1798 pcpu_chunk_relocate(chunk, -1);
1799 } else {
1800 spin_lock_irqsave(&pcpu_lock, flags);
1801 }
1802
1803 goto restart;
1804
1805area_found:
1806 pcpu_stats_area_alloc(chunk, size);
1807 spin_unlock_irqrestore(&pcpu_lock, flags);
1808
1809 /* populate if not all pages are already there */
1810 if (!is_atomic) {
1811 unsigned int page_start, page_end, rs, re;
1812
1813 page_start = PFN_DOWN(off);
1814 page_end = PFN_UP(off + size);
1815
1816 bitmap_for_each_clear_region(chunk->populated, rs, re,
1817 page_start, page_end) {
1818 WARN_ON(chunk->immutable);
1819
1820 ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1821
1822 spin_lock_irqsave(&pcpu_lock, flags);
1823 if (ret) {
1824 pcpu_free_area(chunk, off);
1825 err = "failed to populate";
1826 goto fail_unlock;
1827 }
1828 pcpu_chunk_populated(chunk, rs, re);
1829 spin_unlock_irqrestore(&pcpu_lock, flags);
1830 }
1831
1832 mutex_unlock(&pcpu_alloc_mutex);
1833 }
1834
1835 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1836 pcpu_schedule_balance_work();
1837
1838 /* clear the areas and return address relative to base address */
1839 for_each_possible_cpu(cpu)
1840 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1841
1842 ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1843 kmemleak_alloc_percpu(ptr, size, gfp);
1844
1845 trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
1846 chunk->base_addr, off, ptr);
1847
1848 pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
1849
1850 return ptr;
1851
1852fail_unlock:
1853 spin_unlock_irqrestore(&pcpu_lock, flags);
1854fail:
1855 trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1856
1857 if (!is_atomic && do_warn && warn_limit) {
1858 pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1859 size, align, is_atomic, err);
1860 dump_stack();
1861 if (!--warn_limit)
1862 pr_info("limit reached, disable warning\n");
1863 }
1864 if (is_atomic) {
1865 /* see the flag handling in pcpu_blance_workfn() */
1866 pcpu_atomic_alloc_failed = true;
1867 pcpu_schedule_balance_work();
1868 } else {
1869 mutex_unlock(&pcpu_alloc_mutex);
1870 }
1871
1872 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1873
1874 return NULL;
1875}
1876
1877/**
1878 * __alloc_percpu_gfp - allocate dynamic percpu area
1879 * @size: size of area to allocate in bytes
1880 * @align: alignment of area (max PAGE_SIZE)
1881 * @gfp: allocation flags
1882 *
1883 * Allocate zero-filled percpu area of @size bytes aligned at @align. If
1884 * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1885 * be called from any context but is a lot more likely to fail. If @gfp
1886 * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1887 * allocation requests.
1888 *
1889 * RETURNS:
1890 * Percpu pointer to the allocated area on success, NULL on failure.
1891 */
1892void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1893{
1894 return pcpu_alloc(size, align, false, gfp);
1895}
1896EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1897
1898/**
1899 * __alloc_percpu - allocate dynamic percpu area
1900 * @size: size of area to allocate in bytes
1901 * @align: alignment of area (max PAGE_SIZE)
1902 *
1903 * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1904 */
1905void __percpu *__alloc_percpu(size_t size, size_t align)
1906{
1907 return pcpu_alloc(size, align, false, GFP_KERNEL);
1908}
1909EXPORT_SYMBOL_GPL(__alloc_percpu);
1910
1911/**
1912 * __alloc_reserved_percpu - allocate reserved percpu area
1913 * @size: size of area to allocate in bytes
1914 * @align: alignment of area (max PAGE_SIZE)
1915 *
1916 * Allocate zero-filled percpu area of @size bytes aligned at @align
1917 * from reserved percpu area if arch has set it up; otherwise,
1918 * allocation is served from the same dynamic area. Might sleep.
1919 * Might trigger writeouts.
1920 *
1921 * CONTEXT:
1922 * Does GFP_KERNEL allocation.
1923 *
1924 * RETURNS:
1925 * Percpu pointer to the allocated area on success, NULL on failure.
1926 */
1927void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1928{
1929 return pcpu_alloc(size, align, true, GFP_KERNEL);
1930}
1931
1932/**
1933 * __pcpu_balance_workfn - manage the amount of free chunks and populated pages
1934 * @type: chunk type
1935 *
1936 * Reclaim all fully free chunks except for the first one. This is also
1937 * responsible for maintaining the pool of empty populated pages. However,
1938 * it is possible that this is called when physical memory is scarce causing
1939 * OOM killer to be triggered. We should avoid doing so until an actual
1940 * allocation causes the failure as it is possible that requests can be
1941 * serviced from already backed regions.
1942 */
1943static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
1944{
1945 /* gfp flags passed to underlying allocators */
1946 const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
1947 LIST_HEAD(to_free);
1948 struct list_head *pcpu_slot = pcpu_chunk_list(type);
1949 struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
1950 struct pcpu_chunk *chunk, *next;
1951 int slot, nr_to_pop, ret;
1952
1953 /*
1954 * There's no reason to keep around multiple unused chunks and VM
1955 * areas can be scarce. Destroy all free chunks except for one.
1956 */
1957 mutex_lock(&pcpu_alloc_mutex);
1958 spin_lock_irq(&pcpu_lock);
1959
1960 list_for_each_entry_safe(chunk, next, free_head, list) {
1961 WARN_ON(chunk->immutable);
1962
1963 /* spare the first one */
1964 if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1965 continue;
1966
1967 list_move(&chunk->list, &to_free);
1968 }
1969
1970 spin_unlock_irq(&pcpu_lock);
1971
1972 list_for_each_entry_safe(chunk, next, &to_free, list) {
1973 unsigned int rs, re;
1974
1975 bitmap_for_each_set_region(chunk->populated, rs, re, 0,
1976 chunk->nr_pages) {
1977 pcpu_depopulate_chunk(chunk, rs, re);
1978 spin_lock_irq(&pcpu_lock);
1979 pcpu_chunk_depopulated(chunk, rs, re);
1980 spin_unlock_irq(&pcpu_lock);
1981 }
1982 pcpu_destroy_chunk(chunk);
1983 cond_resched();
1984 }
1985
1986 /*
1987 * Ensure there are certain number of free populated pages for
1988 * atomic allocs. Fill up from the most packed so that atomic
1989 * allocs don't increase fragmentation. If atomic allocation
1990 * failed previously, always populate the maximum amount. This
1991 * should prevent atomic allocs larger than PAGE_SIZE from keeping
1992 * failing indefinitely; however, large atomic allocs are not
1993 * something we support properly and can be highly unreliable and
1994 * inefficient.
1995 */
1996retry_pop:
1997 if (pcpu_atomic_alloc_failed) {
1998 nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
1999 /* best effort anyway, don't worry about synchronization */
2000 pcpu_atomic_alloc_failed = false;
2001 } else {
2002 nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
2003 pcpu_nr_empty_pop_pages,
2004 0, PCPU_EMPTY_POP_PAGES_HIGH);
2005 }
2006
2007 for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
2008 unsigned int nr_unpop = 0, rs, re;
2009
2010 if (!nr_to_pop)
2011 break;
2012
2013 spin_lock_irq(&pcpu_lock);
2014 list_for_each_entry(chunk, &pcpu_slot[slot], list) {
2015 nr_unpop = chunk->nr_pages - chunk->nr_populated;
2016 if (nr_unpop)
2017 break;
2018 }
2019 spin_unlock_irq(&pcpu_lock);
2020
2021 if (!nr_unpop)
2022 continue;
2023
2024 /* @chunk can't go away while pcpu_alloc_mutex is held */
2025 bitmap_for_each_clear_region(chunk->populated, rs, re, 0,
2026 chunk->nr_pages) {
2027 int nr = min_t(int, re - rs, nr_to_pop);
2028
2029 ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
2030 if (!ret) {
2031 nr_to_pop -= nr;
2032 spin_lock_irq(&pcpu_lock);
2033 pcpu_chunk_populated(chunk, rs, rs + nr);
2034 spin_unlock_irq(&pcpu_lock);
2035 } else {
2036 nr_to_pop = 0;
2037 }
2038
2039 if (!nr_to_pop)
2040 break;
2041 }
2042 }
2043
2044 if (nr_to_pop) {
2045 /* ran out of chunks to populate, create a new one and retry */
2046 chunk = pcpu_create_chunk(type, gfp);
2047 if (chunk) {
2048 spin_lock_irq(&pcpu_lock);
2049 pcpu_chunk_relocate(chunk, -1);
2050 spin_unlock_irq(&pcpu_lock);
2051 goto retry_pop;
2052 }
2053 }
2054
2055 mutex_unlock(&pcpu_alloc_mutex);
2056}
2057
2058/**
2059 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
2060 * @work: unused
2061 *
2062 * Call __pcpu_balance_workfn() for each chunk type.
2063 */
2064static void pcpu_balance_workfn(struct work_struct *work)
2065{
2066 enum pcpu_chunk_type type;
2067
2068 for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
2069 __pcpu_balance_workfn(type);
2070}
2071
2072/**
2073 * free_percpu - free percpu area
2074 * @ptr: pointer to area to free
2075 *
2076 * Free percpu area @ptr.
2077 *
2078 * CONTEXT:
2079 * Can be called from atomic context.
2080 */
2081void free_percpu(void __percpu *ptr)
2082{
2083 void *addr;
2084 struct pcpu_chunk *chunk;
2085 unsigned long flags;
2086 int size, off;
2087 bool need_balance = false;
2088 struct list_head *pcpu_slot;
2089
2090 if (!ptr)
2091 return;
2092
2093 kmemleak_free_percpu(ptr);
2094
2095 addr = __pcpu_ptr_to_addr(ptr);
2096
2097 spin_lock_irqsave(&pcpu_lock, flags);
2098
2099 chunk = pcpu_chunk_addr_search(addr);
2100 off = addr - chunk->base_addr;
2101
2102 size = pcpu_free_area(chunk, off);
2103
2104 pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
2105
2106 pcpu_memcg_free_hook(chunk, off, size);
2107
2108 /* if there are more than one fully free chunks, wake up grim reaper */
2109 if (chunk->free_bytes == pcpu_unit_size) {
2110 struct pcpu_chunk *pos;
2111
2112 list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
2113 if (pos != chunk) {
2114 need_balance = true;
2115 break;
2116 }
2117 }
2118
2119 trace_percpu_free_percpu(chunk->base_addr, off, ptr);
2120
2121 spin_unlock_irqrestore(&pcpu_lock, flags);
2122
2123 if (need_balance)
2124 pcpu_schedule_balance_work();
2125}
2126EXPORT_SYMBOL_GPL(free_percpu);
2127
2128bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
2129{
2130#ifdef CONFIG_SMP
2131 const size_t static_size = __per_cpu_end - __per_cpu_start;
2132 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2133 unsigned int cpu;
2134
2135 for_each_possible_cpu(cpu) {
2136 void *start = per_cpu_ptr(base, cpu);
2137 void *va = (void *)addr;
2138
2139 if (va >= start && va < start + static_size) {
2140 if (can_addr) {
2141 *can_addr = (unsigned long) (va - start);
2142 *can_addr += (unsigned long)
2143 per_cpu_ptr(base, get_boot_cpu_id());
2144 }
2145 return true;
2146 }
2147 }
2148#endif
2149 /* on UP, can't distinguish from other static vars, always false */
2150 return false;
2151}
2152
2153/**
2154 * is_kernel_percpu_address - test whether address is from static percpu area
2155 * @addr: address to test
2156 *
2157 * Test whether @addr belongs to in-kernel static percpu area. Module
2158 * static percpu areas are not considered. For those, use
2159 * is_module_percpu_address().
2160 *
2161 * RETURNS:
2162 * %true if @addr is from in-kernel static percpu area, %false otherwise.
2163 */
2164bool is_kernel_percpu_address(unsigned long addr)
2165{
2166 return __is_kernel_percpu_address(addr, NULL);
2167}
2168
2169/**
2170 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2171 * @addr: the address to be converted to physical address
2172 *
2173 * Given @addr which is dereferenceable address obtained via one of
2174 * percpu access macros, this function translates it into its physical
2175 * address. The caller is responsible for ensuring @addr stays valid
2176 * until this function finishes.
2177 *
2178 * percpu allocator has special setup for the first chunk, which currently
2179 * supports either embedding in linear address space or vmalloc mapping,
2180 * and, from the second one, the backing allocator (currently either vm or
2181 * km) provides translation.
2182 *
2183 * The addr can be translated simply without checking if it falls into the
2184 * first chunk. But the current code reflects better how percpu allocator
2185 * actually works, and the verification can discover both bugs in percpu
2186 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2187 * code.
2188 *
2189 * RETURNS:
2190 * The physical address for @addr.
2191 */
2192phys_addr_t per_cpu_ptr_to_phys(void *addr)
2193{
2194 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2195 bool in_first_chunk = false;
2196 unsigned long first_low, first_high;
2197 unsigned int cpu;
2198
2199 /*
2200 * The following test on unit_low/high isn't strictly
2201 * necessary but will speed up lookups of addresses which
2202 * aren't in the first chunk.
2203 *
2204 * The address check is against full chunk sizes. pcpu_base_addr
2205 * points to the beginning of the first chunk including the
2206 * static region. Assumes good intent as the first chunk may
2207 * not be full (ie. < pcpu_unit_pages in size).
2208 */
2209 first_low = (unsigned long)pcpu_base_addr +
2210 pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2211 first_high = (unsigned long)pcpu_base_addr +
2212 pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2213 if ((unsigned long)addr >= first_low &&
2214 (unsigned long)addr < first_high) {
2215 for_each_possible_cpu(cpu) {
2216 void *start = per_cpu_ptr(base, cpu);
2217
2218 if (addr >= start && addr < start + pcpu_unit_size) {
2219 in_first_chunk = true;
2220 break;
2221 }
2222 }
2223 }
2224
2225 if (in_first_chunk) {
2226 if (!is_vmalloc_addr(addr))
2227 return __pa(addr);
2228 else
2229 return page_to_phys(vmalloc_to_page(addr)) +
2230 offset_in_page(addr);
2231 } else
2232 return page_to_phys(pcpu_addr_to_page(addr)) +
2233 offset_in_page(addr);
2234}
2235
2236/**
2237 * pcpu_alloc_alloc_info - allocate percpu allocation info
2238 * @nr_groups: the number of groups
2239 * @nr_units: the number of units
2240 *
2241 * Allocate ai which is large enough for @nr_groups groups containing
2242 * @nr_units units. The returned ai's groups[0].cpu_map points to the
2243 * cpu_map array which is long enough for @nr_units and filled with
2244 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
2245 * pointer of other groups.
2246 *
2247 * RETURNS:
2248 * Pointer to the allocated pcpu_alloc_info on success, NULL on
2249 * failure.
2250 */
2251struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2252 int nr_units)
2253{
2254 struct pcpu_alloc_info *ai;
2255 size_t base_size, ai_size;
2256 void *ptr;
2257 int unit;
2258
2259 base_size = ALIGN(struct_size(ai, groups, nr_groups),
2260 __alignof__(ai->groups[0].cpu_map[0]));
2261 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2262
2263 ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2264 if (!ptr)
2265 return NULL;
2266 ai = ptr;
2267 ptr += base_size;
2268
2269 ai->groups[0].cpu_map = ptr;
2270
2271 for (unit = 0; unit < nr_units; unit++)
2272 ai->groups[0].cpu_map[unit] = NR_CPUS;
2273
2274 ai->nr_groups = nr_groups;
2275 ai->__ai_size = PFN_ALIGN(ai_size);
2276
2277 return ai;
2278}
2279
2280/**
2281 * pcpu_free_alloc_info - free percpu allocation info
2282 * @ai: pcpu_alloc_info to free
2283 *
2284 * Free @ai which was allocated by pcpu_alloc_alloc_info().
2285 */
2286void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2287{
2288 memblock_free_early(__pa(ai), ai->__ai_size);
2289}
2290
2291/**
2292 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2293 * @lvl: loglevel
2294 * @ai: allocation info to dump
2295 *
2296 * Print out information about @ai using loglevel @lvl.
2297 */
2298static void pcpu_dump_alloc_info(const char *lvl,
2299 const struct pcpu_alloc_info *ai)
2300{
2301 int group_width = 1, cpu_width = 1, width;
2302 char empty_str[] = "--------";
2303 int alloc = 0, alloc_end = 0;
2304 int group, v;
2305 int upa, apl; /* units per alloc, allocs per line */
2306
2307 v = ai->nr_groups;
2308 while (v /= 10)
2309 group_width++;
2310
2311 v = num_possible_cpus();
2312 while (v /= 10)
2313 cpu_width++;
2314 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2315
2316 upa = ai->alloc_size / ai->unit_size;
2317 width = upa * (cpu_width + 1) + group_width + 3;
2318 apl = rounddown_pow_of_two(max(60 / width, 1));
2319
2320 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2321 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2322 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2323
2324 for (group = 0; group < ai->nr_groups; group++) {
2325 const struct pcpu_group_info *gi = &ai->groups[group];
2326 int unit = 0, unit_end = 0;
2327
2328 BUG_ON(gi->nr_units % upa);
2329 for (alloc_end += gi->nr_units / upa;
2330 alloc < alloc_end; alloc++) {
2331 if (!(alloc % apl)) {
2332 pr_cont("\n");
2333 printk("%spcpu-alloc: ", lvl);
2334 }
2335 pr_cont("[%0*d] ", group_width, group);
2336
2337 for (unit_end += upa; unit < unit_end; unit++)
2338 if (gi->cpu_map[unit] != NR_CPUS)
2339 pr_cont("%0*d ",
2340 cpu_width, gi->cpu_map[unit]);
2341 else
2342 pr_cont("%s ", empty_str);
2343 }
2344 }
2345 pr_cont("\n");
2346}
2347
2348/**
2349 * pcpu_setup_first_chunk - initialize the first percpu chunk
2350 * @ai: pcpu_alloc_info describing how to percpu area is shaped
2351 * @base_addr: mapped address
2352 *
2353 * Initialize the first percpu chunk which contains the kernel static
2354 * percpu area. This function is to be called from arch percpu area
2355 * setup path.
2356 *
2357 * @ai contains all information necessary to initialize the first
2358 * chunk and prime the dynamic percpu allocator.
2359 *
2360 * @ai->static_size is the size of static percpu area.
2361 *
2362 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2363 * reserve after the static area in the first chunk. This reserves
2364 * the first chunk such that it's available only through reserved
2365 * percpu allocation. This is primarily used to serve module percpu
2366 * static areas on architectures where the addressing model has
2367 * limited offset range for symbol relocations to guarantee module
2368 * percpu symbols fall inside the relocatable range.
2369 *
2370 * @ai->dyn_size determines the number of bytes available for dynamic
2371 * allocation in the first chunk. The area between @ai->static_size +
2372 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2373 *
2374 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2375 * and equal to or larger than @ai->static_size + @ai->reserved_size +
2376 * @ai->dyn_size.
2377 *
2378 * @ai->atom_size is the allocation atom size and used as alignment
2379 * for vm areas.
2380 *
2381 * @ai->alloc_size is the allocation size and always multiple of
2382 * @ai->atom_size. This is larger than @ai->atom_size if
2383 * @ai->unit_size is larger than @ai->atom_size.
2384 *
2385 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2386 * percpu areas. Units which should be colocated are put into the
2387 * same group. Dynamic VM areas will be allocated according to these
2388 * groupings. If @ai->nr_groups is zero, a single group containing
2389 * all units is assumed.
2390 *
2391 * The caller should have mapped the first chunk at @base_addr and
2392 * copied static data to each unit.
2393 *
2394 * The first chunk will always contain a static and a dynamic region.
2395 * However, the static region is not managed by any chunk. If the first
2396 * chunk also contains a reserved region, it is served by two chunks -
2397 * one for the reserved region and one for the dynamic region. They
2398 * share the same vm, but use offset regions in the area allocation map.
2399 * The chunk serving the dynamic region is circulated in the chunk slots
2400 * and available for dynamic allocation like any other chunk.
2401 */
2402void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2403 void *base_addr)
2404{
2405 size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2406 size_t static_size, dyn_size;
2407 struct pcpu_chunk *chunk;
2408 unsigned long *group_offsets;
2409 size_t *group_sizes;
2410 unsigned long *unit_off;
2411 unsigned int cpu;
2412 int *unit_map;
2413 int group, unit, i;
2414 int map_size;
2415 unsigned long tmp_addr;
2416 size_t alloc_size;
2417 enum pcpu_chunk_type type;
2418
2419#define PCPU_SETUP_BUG_ON(cond) do { \
2420 if (unlikely(cond)) { \
2421 pr_emerg("failed to initialize, %s\n", #cond); \
2422 pr_emerg("cpu_possible_mask=%*pb\n", \
2423 cpumask_pr_args(cpu_possible_mask)); \
2424 pcpu_dump_alloc_info(KERN_EMERG, ai); \
2425 BUG(); \
2426 } \
2427} while (0)
2428
2429 /* sanity checks */
2430 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2431#ifdef CONFIG_SMP
2432 PCPU_SETUP_BUG_ON(!ai->static_size);
2433 PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2434#endif
2435 PCPU_SETUP_BUG_ON(!base_addr);
2436 PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2437 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2438 PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2439 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2440 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2441 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2442 PCPU_SETUP_BUG_ON(!ai->dyn_size);
2443 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2444 PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2445 IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2446 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2447
2448 /* process group information and build config tables accordingly */
2449 alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2450 group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2451 if (!group_offsets)
2452 panic("%s: Failed to allocate %zu bytes\n", __func__,
2453 alloc_size);
2454
2455 alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2456 group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2457 if (!group_sizes)
2458 panic("%s: Failed to allocate %zu bytes\n", __func__,
2459 alloc_size);
2460
2461 alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2462 unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2463 if (!unit_map)
2464 panic("%s: Failed to allocate %zu bytes\n", __func__,
2465 alloc_size);
2466
2467 alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2468 unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2469 if (!unit_off)
2470 panic("%s: Failed to allocate %zu bytes\n", __func__,
2471 alloc_size);
2472
2473 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2474 unit_map[cpu] = UINT_MAX;
2475
2476 pcpu_low_unit_cpu = NR_CPUS;
2477 pcpu_high_unit_cpu = NR_CPUS;
2478
2479 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2480 const struct pcpu_group_info *gi = &ai->groups[group];
2481
2482 group_offsets[group] = gi->base_offset;
2483 group_sizes[group] = gi->nr_units * ai->unit_size;
2484
2485 for (i = 0; i < gi->nr_units; i++) {
2486 cpu = gi->cpu_map[i];
2487 if (cpu == NR_CPUS)
2488 continue;
2489
2490 PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2491 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2492 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2493
2494 unit_map[cpu] = unit + i;
2495 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2496
2497 /* determine low/high unit_cpu */
2498 if (pcpu_low_unit_cpu == NR_CPUS ||
2499 unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2500 pcpu_low_unit_cpu = cpu;
2501 if (pcpu_high_unit_cpu == NR_CPUS ||
2502 unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2503 pcpu_high_unit_cpu = cpu;
2504 }
2505 }
2506 pcpu_nr_units = unit;
2507
2508 for_each_possible_cpu(cpu)
2509 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2510
2511 /* we're done parsing the input, undefine BUG macro and dump config */
2512#undef PCPU_SETUP_BUG_ON
2513 pcpu_dump_alloc_info(KERN_DEBUG, ai);
2514
2515 pcpu_nr_groups = ai->nr_groups;
2516 pcpu_group_offsets = group_offsets;
2517 pcpu_group_sizes = group_sizes;
2518 pcpu_unit_map = unit_map;
2519 pcpu_unit_offsets = unit_off;
2520
2521 /* determine basic parameters */
2522 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2523 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2524 pcpu_atom_size = ai->atom_size;
2525 pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
2526 BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
2527
2528 pcpu_stats_save_ai(ai);
2529
2530 /*
2531 * Allocate chunk slots. The additional last slot is for
2532 * empty chunks.
2533 */
2534 pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
2535 pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
2536 sizeof(pcpu_chunk_lists[0]) *
2537 PCPU_NR_CHUNK_TYPES,
2538 SMP_CACHE_BYTES);
2539 if (!pcpu_chunk_lists)
2540 panic("%s: Failed to allocate %zu bytes\n", __func__,
2541 pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]) *
2542 PCPU_NR_CHUNK_TYPES);
2543
2544 for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
2545 for (i = 0; i < pcpu_nr_slots; i++)
2546 INIT_LIST_HEAD(&pcpu_chunk_list(type)[i]);
2547
2548 /*
2549 * The end of the static region needs to be aligned with the
2550 * minimum allocation size as this offsets the reserved and
2551 * dynamic region. The first chunk ends page aligned by
2552 * expanding the dynamic region, therefore the dynamic region
2553 * can be shrunk to compensate while still staying above the
2554 * configured sizes.
2555 */
2556 static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2557 dyn_size = ai->dyn_size - (static_size - ai->static_size);
2558
2559 /*
2560 * Initialize first chunk.
2561 * If the reserved_size is non-zero, this initializes the reserved
2562 * chunk. If the reserved_size is zero, the reserved chunk is NULL
2563 * and the dynamic region is initialized here. The first chunk,
2564 * pcpu_first_chunk, will always point to the chunk that serves
2565 * the dynamic region.
2566 */
2567 tmp_addr = (unsigned long)base_addr + static_size;
2568 map_size = ai->reserved_size ?: dyn_size;
2569 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2570
2571 /* init dynamic chunk if necessary */
2572 if (ai->reserved_size) {
2573 pcpu_reserved_chunk = chunk;
2574
2575 tmp_addr = (unsigned long)base_addr + static_size +
2576 ai->reserved_size;
2577 map_size = dyn_size;
2578 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2579 }
2580
2581 /* link the first chunk in */
2582 pcpu_first_chunk = chunk;
2583 pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2584 pcpu_chunk_relocate(pcpu_first_chunk, -1);
2585
2586 /* include all regions of the first chunk */
2587 pcpu_nr_populated += PFN_DOWN(size_sum);
2588
2589 pcpu_stats_chunk_alloc();
2590 trace_percpu_create_chunk(base_addr);
2591
2592 /* we're done */
2593 pcpu_base_addr = base_addr;
2594}
2595
2596#ifdef CONFIG_SMP
2597
2598const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2599 [PCPU_FC_AUTO] = "auto",
2600 [PCPU_FC_EMBED] = "embed",
2601 [PCPU_FC_PAGE] = "page",
2602};
2603
2604enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2605
2606static int __init percpu_alloc_setup(char *str)
2607{
2608 if (!str)
2609 return -EINVAL;
2610
2611 if (0)
2612 /* nada */;
2613#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2614 else if (!strcmp(str, "embed"))
2615 pcpu_chosen_fc = PCPU_FC_EMBED;
2616#endif
2617#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2618 else if (!strcmp(str, "page"))
2619 pcpu_chosen_fc = PCPU_FC_PAGE;
2620#endif
2621 else
2622 pr_warn("unknown allocator %s specified\n", str);
2623
2624 return 0;
2625}
2626early_param("percpu_alloc", percpu_alloc_setup);
2627
2628/*
2629 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2630 * Build it if needed by the arch config or the generic setup is going
2631 * to be used.
2632 */
2633#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2634 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2635#define BUILD_EMBED_FIRST_CHUNK
2636#endif
2637
2638/* build pcpu_page_first_chunk() iff needed by the arch config */
2639#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2640#define BUILD_PAGE_FIRST_CHUNK
2641#endif
2642
2643/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2644#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2645/**
2646 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2647 * @reserved_size: the size of reserved percpu area in bytes
2648 * @dyn_size: minimum free size for dynamic allocation in bytes
2649 * @atom_size: allocation atom size
2650 * @cpu_distance_fn: callback to determine distance between cpus, optional
2651 *
2652 * This function determines grouping of units, their mappings to cpus
2653 * and other parameters considering needed percpu size, allocation
2654 * atom size and distances between CPUs.
2655 *
2656 * Groups are always multiples of atom size and CPUs which are of
2657 * LOCAL_DISTANCE both ways are grouped together and share space for
2658 * units in the same group. The returned configuration is guaranteed
2659 * to have CPUs on different nodes on different groups and >=75% usage
2660 * of allocated virtual address space.
2661 *
2662 * RETURNS:
2663 * On success, pointer to the new allocation_info is returned. On
2664 * failure, ERR_PTR value is returned.
2665 */
2666static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
2667 size_t reserved_size, size_t dyn_size,
2668 size_t atom_size,
2669 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2670{
2671 static int group_map[NR_CPUS] __initdata;
2672 static int group_cnt[NR_CPUS] __initdata;
2673 const size_t static_size = __per_cpu_end - __per_cpu_start;
2674 int nr_groups = 1, nr_units = 0;
2675 size_t size_sum, min_unit_size, alloc_size;
2676 int upa, max_upa, best_upa; /* units_per_alloc */
2677 int last_allocs, group, unit;
2678 unsigned int cpu, tcpu;
2679 struct pcpu_alloc_info *ai;
2680 unsigned int *cpu_map;
2681
2682 /* this function may be called multiple times */
2683 memset(group_map, 0, sizeof(group_map));
2684 memset(group_cnt, 0, sizeof(group_cnt));
2685
2686 /* calculate size_sum and ensure dyn_size is enough for early alloc */
2687 size_sum = PFN_ALIGN(static_size + reserved_size +
2688 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2689 dyn_size = size_sum - static_size - reserved_size;
2690
2691 /*
2692 * Determine min_unit_size, alloc_size and max_upa such that
2693 * alloc_size is multiple of atom_size and is the smallest
2694 * which can accommodate 4k aligned segments which are equal to
2695 * or larger than min_unit_size.
2696 */
2697 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2698
2699 /* determine the maximum # of units that can fit in an allocation */
2700 alloc_size = roundup(min_unit_size, atom_size);
2701 upa = alloc_size / min_unit_size;
2702 while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2703 upa--;
2704 max_upa = upa;
2705
2706 /* group cpus according to their proximity */
2707 for_each_possible_cpu(cpu) {
2708 group = 0;
2709 next_group:
2710 for_each_possible_cpu(tcpu) {
2711 if (cpu == tcpu)
2712 break;
2713 if (group_map[tcpu] == group && cpu_distance_fn &&
2714 (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
2715 cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
2716 group++;
2717 nr_groups = max(nr_groups, group + 1);
2718 goto next_group;
2719 }
2720 }
2721 group_map[cpu] = group;
2722 group_cnt[group]++;
2723 }
2724
2725 /*
2726 * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2727 * Expand the unit_size until we use >= 75% of the units allocated.
2728 * Related to atom_size, which could be much larger than the unit_size.
2729 */
2730 last_allocs = INT_MAX;
2731 for (upa = max_upa; upa; upa--) {
2732 int allocs = 0, wasted = 0;
2733
2734 if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2735 continue;
2736
2737 for (group = 0; group < nr_groups; group++) {
2738 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2739 allocs += this_allocs;
2740 wasted += this_allocs * upa - group_cnt[group];
2741 }
2742
2743 /*
2744 * Don't accept if wastage is over 1/3. The
2745 * greater-than comparison ensures upa==1 always
2746 * passes the following check.
2747 */
2748 if (wasted > num_possible_cpus() / 3)
2749 continue;
2750
2751 /* and then don't consume more memory */
2752 if (allocs > last_allocs)
2753 break;
2754 last_allocs = allocs;
2755 best_upa = upa;
2756 }
2757 upa = best_upa;
2758
2759 /* allocate and fill alloc_info */
2760 for (group = 0; group < nr_groups; group++)
2761 nr_units += roundup(group_cnt[group], upa);
2762
2763 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2764 if (!ai)
2765 return ERR_PTR(-ENOMEM);
2766 cpu_map = ai->groups[0].cpu_map;
2767
2768 for (group = 0; group < nr_groups; group++) {
2769 ai->groups[group].cpu_map = cpu_map;
2770 cpu_map += roundup(group_cnt[group], upa);
2771 }
2772
2773 ai->static_size = static_size;
2774 ai->reserved_size = reserved_size;
2775 ai->dyn_size = dyn_size;
2776 ai->unit_size = alloc_size / upa;
2777 ai->atom_size = atom_size;
2778 ai->alloc_size = alloc_size;
2779
2780 for (group = 0, unit = 0; group < nr_groups; group++) {
2781 struct pcpu_group_info *gi = &ai->groups[group];
2782
2783 /*
2784 * Initialize base_offset as if all groups are located
2785 * back-to-back. The caller should update this to
2786 * reflect actual allocation.
2787 */
2788 gi->base_offset = unit * ai->unit_size;
2789
2790 for_each_possible_cpu(cpu)
2791 if (group_map[cpu] == group)
2792 gi->cpu_map[gi->nr_units++] = cpu;
2793 gi->nr_units = roundup(gi->nr_units, upa);
2794 unit += gi->nr_units;
2795 }
2796 BUG_ON(unit != nr_units);
2797
2798 return ai;
2799}
2800#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
2801
2802#if defined(BUILD_EMBED_FIRST_CHUNK)
2803/**
2804 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
2805 * @reserved_size: the size of reserved percpu area in bytes
2806 * @dyn_size: minimum free size for dynamic allocation in bytes
2807 * @atom_size: allocation atom size
2808 * @cpu_distance_fn: callback to determine distance between cpus, optional
2809 * @alloc_fn: function to allocate percpu page
2810 * @free_fn: function to free percpu page
2811 *
2812 * This is a helper to ease setting up embedded first percpu chunk and
2813 * can be called where pcpu_setup_first_chunk() is expected.
2814 *
2815 * If this function is used to setup the first chunk, it is allocated
2816 * by calling @alloc_fn and used as-is without being mapped into
2817 * vmalloc area. Allocations are always whole multiples of @atom_size
2818 * aligned to @atom_size.
2819 *
2820 * This enables the first chunk to piggy back on the linear physical
2821 * mapping which often uses larger page size. Please note that this
2822 * can result in very sparse cpu->unit mapping on NUMA machines thus
2823 * requiring large vmalloc address space. Don't use this allocator if
2824 * vmalloc space is not orders of magnitude larger than distances
2825 * between node memory addresses (ie. 32bit NUMA machines).
2826 *
2827 * @dyn_size specifies the minimum dynamic area size.
2828 *
2829 * If the needed size is smaller than the minimum or specified unit
2830 * size, the leftover is returned using @free_fn.
2831 *
2832 * RETURNS:
2833 * 0 on success, -errno on failure.
2834 */
2835int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
2836 size_t atom_size,
2837 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
2838 pcpu_fc_alloc_fn_t alloc_fn,
2839 pcpu_fc_free_fn_t free_fn)
2840{
2841 void *base = (void *)ULONG_MAX;
2842 void **areas = NULL;
2843 struct pcpu_alloc_info *ai;
2844 size_t size_sum, areas_size;
2845 unsigned long max_distance;
2846 int group, i, highest_group, rc = 0;
2847
2848 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
2849 cpu_distance_fn);
2850 if (IS_ERR(ai))
2851 return PTR_ERR(ai);
2852
2853 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2854 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
2855
2856 areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
2857 if (!areas) {
2858 rc = -ENOMEM;
2859 goto out_free;
2860 }
2861
2862 /* allocate, copy and determine base address & max_distance */
2863 highest_group = 0;
2864 for (group = 0; group < ai->nr_groups; group++) {
2865 struct pcpu_group_info *gi = &ai->groups[group];
2866 unsigned int cpu = NR_CPUS;
2867 void *ptr;
2868
2869 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
2870 cpu = gi->cpu_map[i];
2871 BUG_ON(cpu == NR_CPUS);
2872
2873 /* allocate space for the whole group */
2874 ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
2875 if (!ptr) {
2876 rc = -ENOMEM;
2877 goto out_free_areas;
2878 }
2879 /* kmemleak tracks the percpu allocations separately */
2880 kmemleak_free(ptr);
2881 areas[group] = ptr;
2882
2883 base = min(ptr, base);
2884 if (ptr > areas[highest_group])
2885 highest_group = group;
2886 }
2887 max_distance = areas[highest_group] - base;
2888 max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
2889
2890 /* warn if maximum distance is further than 75% of vmalloc space */
2891 if (max_distance > VMALLOC_TOTAL * 3 / 4) {
2892 pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
2893 max_distance, VMALLOC_TOTAL);
2894#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2895 /* and fail if we have fallback */
2896 rc = -EINVAL;
2897 goto out_free_areas;
2898#endif
2899 }
2900
2901 /*
2902 * Copy data and free unused parts. This should happen after all
2903 * allocations are complete; otherwise, we may end up with
2904 * overlapping groups.
2905 */
2906 for (group = 0; group < ai->nr_groups; group++) {
2907 struct pcpu_group_info *gi = &ai->groups[group];
2908 void *ptr = areas[group];
2909
2910 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
2911 if (gi->cpu_map[i] == NR_CPUS) {
2912 /* unused unit, free whole */
2913 free_fn(ptr, ai->unit_size);
2914 continue;
2915 }
2916 /* copy and return the unused part */
2917 memcpy(ptr, __per_cpu_load, ai->static_size);
2918 free_fn(ptr + size_sum, ai->unit_size - size_sum);
2919 }
2920 }
2921
2922 /* base address is now known, determine group base offsets */
2923 for (group = 0; group < ai->nr_groups; group++) {
2924 ai->groups[group].base_offset = areas[group] - base;
2925 }
2926
2927 pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
2928 PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
2929 ai->dyn_size, ai->unit_size);
2930
2931 pcpu_setup_first_chunk(ai, base);
2932 goto out_free;
2933
2934out_free_areas:
2935 for (group = 0; group < ai->nr_groups; group++)
2936 if (areas[group])
2937 free_fn(areas[group],
2938 ai->groups[group].nr_units * ai->unit_size);
2939out_free:
2940 pcpu_free_alloc_info(ai);
2941 if (areas)
2942 memblock_free_early(__pa(areas), areas_size);
2943 return rc;
2944}
2945#endif /* BUILD_EMBED_FIRST_CHUNK */
2946
2947#ifdef BUILD_PAGE_FIRST_CHUNK
2948/**
2949 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
2950 * @reserved_size: the size of reserved percpu area in bytes
2951 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
2952 * @free_fn: function to free percpu page, always called with PAGE_SIZE
2953 * @populate_pte_fn: function to populate pte
2954 *
2955 * This is a helper to ease setting up page-remapped first percpu
2956 * chunk and can be called where pcpu_setup_first_chunk() is expected.
2957 *
2958 * This is the basic allocator. Static percpu area is allocated
2959 * page-by-page into vmalloc area.
2960 *
2961 * RETURNS:
2962 * 0 on success, -errno on failure.
2963 */
2964int __init pcpu_page_first_chunk(size_t reserved_size,
2965 pcpu_fc_alloc_fn_t alloc_fn,
2966 pcpu_fc_free_fn_t free_fn,
2967 pcpu_fc_populate_pte_fn_t populate_pte_fn)
2968{
2969 static struct vm_struct vm;
2970 struct pcpu_alloc_info *ai;
2971 char psize_str[16];
2972 int unit_pages;
2973 size_t pages_size;
2974 struct page **pages;
2975 int unit, i, j, rc = 0;
2976 int upa;
2977 int nr_g0_units;
2978
2979 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
2980
2981 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
2982 if (IS_ERR(ai))
2983 return PTR_ERR(ai);
2984 BUG_ON(ai->nr_groups != 1);
2985 upa = ai->alloc_size/ai->unit_size;
2986 nr_g0_units = roundup(num_possible_cpus(), upa);
2987 if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
2988 pcpu_free_alloc_info(ai);
2989 return -EINVAL;
2990 }
2991
2992 unit_pages = ai->unit_size >> PAGE_SHIFT;
2993
2994 /* unaligned allocations can't be freed, round up to page size */
2995 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
2996 sizeof(pages[0]));
2997 pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
2998 if (!pages)
2999 panic("%s: Failed to allocate %zu bytes\n", __func__,
3000 pages_size);
3001
3002 /* allocate pages */
3003 j = 0;
3004 for (unit = 0; unit < num_possible_cpus(); unit++) {
3005 unsigned int cpu = ai->groups[0].cpu_map[unit];
3006 for (i = 0; i < unit_pages; i++) {
3007 void *ptr;
3008
3009 ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
3010 if (!ptr) {
3011 pr_warn("failed to allocate %s page for cpu%u\n",
3012 psize_str, cpu);
3013 goto enomem;
3014 }
3015 /* kmemleak tracks the percpu allocations separately */
3016 kmemleak_free(ptr);
3017 pages[j++] = virt_to_page(ptr);
3018 }
3019 }
3020
3021 /* allocate vm area, map the pages and copy static data */
3022 vm.flags = VM_ALLOC;
3023 vm.size = num_possible_cpus() * ai->unit_size;
3024 vm_area_register_early(&vm, PAGE_SIZE);
3025
3026 for (unit = 0; unit < num_possible_cpus(); unit++) {
3027 unsigned long unit_addr =
3028 (unsigned long)vm.addr + unit * ai->unit_size;
3029
3030 for (i = 0; i < unit_pages; i++)
3031 populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
3032
3033 /* pte already populated, the following shouldn't fail */
3034 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
3035 unit_pages);
3036 if (rc < 0)
3037 panic("failed to map percpu area, err=%d\n", rc);
3038
3039 /*
3040 * FIXME: Archs with virtual cache should flush local
3041 * cache for the linear mapping here - something
3042 * equivalent to flush_cache_vmap() on the local cpu.
3043 * flush_cache_vmap() can't be used as most supporting
3044 * data structures are not set up yet.
3045 */
3046
3047 /* copy static data */
3048 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
3049 }
3050
3051 /* we're ready, commit */
3052 pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
3053 unit_pages, psize_str, ai->static_size,
3054 ai->reserved_size, ai->dyn_size);
3055
3056 pcpu_setup_first_chunk(ai, vm.addr);
3057 goto out_free_ar;
3058
3059enomem:
3060 while (--j >= 0)
3061 free_fn(page_address(pages[j]), PAGE_SIZE);
3062 rc = -ENOMEM;
3063out_free_ar:
3064 memblock_free_early(__pa(pages), pages_size);
3065 pcpu_free_alloc_info(ai);
3066 return rc;
3067}
3068#endif /* BUILD_PAGE_FIRST_CHUNK */
3069
3070#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
3071/*
3072 * Generic SMP percpu area setup.
3073 *
3074 * The embedding helper is used because its behavior closely resembles
3075 * the original non-dynamic generic percpu area setup. This is
3076 * important because many archs have addressing restrictions and might
3077 * fail if the percpu area is located far away from the previous
3078 * location. As an added bonus, in non-NUMA cases, embedding is
3079 * generally a good idea TLB-wise because percpu area can piggy back
3080 * on the physical linear memory mapping which uses large page
3081 * mappings on applicable archs.
3082 */
3083unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
3084EXPORT_SYMBOL(__per_cpu_offset);
3085
3086static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
3087 size_t align)
3088{
3089 return memblock_alloc_from(size, align, __pa(MAX_DMA_ADDRESS));
3090}
3091
3092static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
3093{
3094 memblock_free_early(__pa(ptr), size);
3095}
3096
3097void __init setup_per_cpu_areas(void)
3098{
3099 unsigned long delta;
3100 unsigned int cpu;
3101 int rc;
3102
3103 /*
3104 * Always reserve area for module percpu variables. That's
3105 * what the legacy allocator did.
3106 */
3107 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
3108 PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
3109 pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
3110 if (rc < 0)
3111 panic("Failed to initialize percpu areas.");
3112
3113 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
3114 for_each_possible_cpu(cpu)
3115 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
3116}
3117#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
3118
3119#else /* CONFIG_SMP */
3120
3121/*
3122 * UP percpu area setup.
3123 *
3124 * UP always uses km-based percpu allocator with identity mapping.
3125 * Static percpu variables are indistinguishable from the usual static
3126 * variables and don't require any special preparation.
3127 */
3128void __init setup_per_cpu_areas(void)
3129{
3130 const size_t unit_size =
3131 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
3132 PERCPU_DYNAMIC_RESERVE));
3133 struct pcpu_alloc_info *ai;
3134 void *fc;
3135
3136 ai = pcpu_alloc_alloc_info(1, 1);
3137 fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3138 if (!ai || !fc)
3139 panic("Failed to allocate memory for percpu areas.");
3140 /* kmemleak tracks the percpu allocations separately */
3141 kmemleak_free(fc);
3142
3143 ai->dyn_size = unit_size;
3144 ai->unit_size = unit_size;
3145 ai->atom_size = unit_size;
3146 ai->alloc_size = unit_size;
3147 ai->groups[0].nr_units = 1;
3148 ai->groups[0].cpu_map[0] = 0;
3149
3150 pcpu_setup_first_chunk(ai, fc);
3151 pcpu_free_alloc_info(ai);
3152}
3153
3154#endif /* CONFIG_SMP */
3155
3156/*
3157 * pcpu_nr_pages - calculate total number of populated backing pages
3158 *
3159 * This reflects the number of pages populated to back chunks. Metadata is
3160 * excluded in the number exposed in meminfo as the number of backing pages
3161 * scales with the number of cpus and can quickly outweigh the memory used for
3162 * metadata. It also keeps this calculation nice and simple.
3163 *
3164 * RETURNS:
3165 * Total number of populated backing pages in use by the allocator.
3166 */
3167unsigned long pcpu_nr_pages(void)
3168{
3169 return pcpu_nr_populated * pcpu_nr_units;
3170}
3171
3172/*
3173 * Percpu allocator is initialized early during boot when neither slab or
3174 * workqueue is available. Plug async management until everything is up
3175 * and running.
3176 */
3177static int __init percpu_enable_async(void)
3178{
3179 pcpu_async_enabled = true;
3180 return 0;
3181}
3182subsys_initcall(percpu_enable_async);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/percpu.c - percpu memory allocator
4 *
5 * Copyright (C) 2009 SUSE Linux Products GmbH
6 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 *
8 * Copyright (C) 2017 Facebook Inc.
9 * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org>
10 *
11 * The percpu allocator handles both static and dynamic areas. Percpu
12 * areas are allocated in chunks which are divided into units. There is
13 * a 1-to-1 mapping for units to possible cpus. These units are grouped
14 * based on NUMA properties of the machine.
15 *
16 * c0 c1 c2
17 * ------------------- ------------------- ------------
18 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
19 * ------------------- ...... ------------------- .... ------------
20 *
21 * Allocation is done by offsets into a unit's address space. Ie., an
22 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
23 * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
24 * and even sparse. Access is handled by configuring percpu base
25 * registers according to the cpu to unit mappings and offsetting the
26 * base address using pcpu_unit_size.
27 *
28 * There is special consideration for the first chunk which must handle
29 * the static percpu variables in the kernel image as allocation services
30 * are not online yet. In short, the first chunk is structured like so:
31 *
32 * <Static | [Reserved] | Dynamic>
33 *
34 * The static data is copied from the original section managed by the
35 * linker. The reserved section, if non-zero, primarily manages static
36 * percpu variables from kernel modules. Finally, the dynamic section
37 * takes care of normal allocations.
38 *
39 * The allocator organizes chunks into lists according to free size and
40 * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
41 * flag should be passed. All memcg-aware allocations are sharing one set
42 * of chunks and all unaccounted allocations and allocations performed
43 * by processes belonging to the root memory cgroup are using the second set.
44 *
45 * The allocator tries to allocate from the fullest chunk first. Each chunk
46 * is managed by a bitmap with metadata blocks. The allocation map is updated
47 * on every allocation and free to reflect the current state while the boundary
48 * map is only updated on allocation. Each metadata block contains
49 * information to help mitigate the need to iterate over large portions
50 * of the bitmap. The reverse mapping from page to chunk is stored in
51 * the page's index. Lastly, units are lazily backed and grow in unison.
52 *
53 * There is a unique conversion that goes on here between bytes and bits.
54 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
55 * tracks the number of pages it is responsible for in nr_pages. Helper
56 * functions are used to convert from between the bytes, bits, and blocks.
57 * All hints are managed in bits unless explicitly stated.
58 *
59 * To use this allocator, arch code should do the following:
60 *
61 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
62 * regular address to percpu pointer and back if they need to be
63 * different from the default
64 *
65 * - use pcpu_setup_first_chunk() during percpu area initialization to
66 * setup the first chunk containing the kernel static percpu area
67 */
68
69#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
70
71#include <linux/bitmap.h>
72#include <linux/cpumask.h>
73#include <linux/memblock.h>
74#include <linux/err.h>
75#include <linux/list.h>
76#include <linux/log2.h>
77#include <linux/mm.h>
78#include <linux/module.h>
79#include <linux/mutex.h>
80#include <linux/percpu.h>
81#include <linux/pfn.h>
82#include <linux/slab.h>
83#include <linux/spinlock.h>
84#include <linux/vmalloc.h>
85#include <linux/workqueue.h>
86#include <linux/kmemleak.h>
87#include <linux/sched.h>
88#include <linux/sched/mm.h>
89#include <linux/memcontrol.h>
90
91#include <asm/cacheflush.h>
92#include <asm/sections.h>
93#include <asm/tlbflush.h>
94#include <asm/io.h>
95
96#define CREATE_TRACE_POINTS
97#include <trace/events/percpu.h>
98
99#include "percpu-internal.h"
100
101/*
102 * The slots are sorted by the size of the biggest continuous free area.
103 * 1-31 bytes share the same slot.
104 */
105#define PCPU_SLOT_BASE_SHIFT 5
106/* chunks in slots below this are subject to being sidelined on failed alloc */
107#define PCPU_SLOT_FAIL_THRESHOLD 3
108
109#define PCPU_EMPTY_POP_PAGES_LOW 2
110#define PCPU_EMPTY_POP_PAGES_HIGH 4
111
112#ifdef CONFIG_SMP
113/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
114#ifndef __addr_to_pcpu_ptr
115#define __addr_to_pcpu_ptr(addr) \
116 (void __percpu *)((unsigned long)(addr) - \
117 (unsigned long)pcpu_base_addr + \
118 (unsigned long)__per_cpu_start)
119#endif
120#ifndef __pcpu_ptr_to_addr
121#define __pcpu_ptr_to_addr(ptr) \
122 (void __force *)((unsigned long)(ptr) + \
123 (unsigned long)pcpu_base_addr - \
124 (unsigned long)__per_cpu_start)
125#endif
126#else /* CONFIG_SMP */
127/* on UP, it's always identity mapped */
128#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
129#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
130#endif /* CONFIG_SMP */
131
132static int pcpu_unit_pages __ro_after_init;
133static int pcpu_unit_size __ro_after_init;
134static int pcpu_nr_units __ro_after_init;
135static int pcpu_atom_size __ro_after_init;
136int pcpu_nr_slots __ro_after_init;
137static int pcpu_free_slot __ro_after_init;
138int pcpu_sidelined_slot __ro_after_init;
139int pcpu_to_depopulate_slot __ro_after_init;
140static size_t pcpu_chunk_struct_size __ro_after_init;
141
142/* cpus with the lowest and highest unit addresses */
143static unsigned int pcpu_low_unit_cpu __ro_after_init;
144static unsigned int pcpu_high_unit_cpu __ro_after_init;
145
146/* the address of the first chunk which starts with the kernel static area */
147void *pcpu_base_addr __ro_after_init;
148
149static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
150const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
151
152/* group information, used for vm allocation */
153static int pcpu_nr_groups __ro_after_init;
154static const unsigned long *pcpu_group_offsets __ro_after_init;
155static const size_t *pcpu_group_sizes __ro_after_init;
156
157/*
158 * The first chunk which always exists. Note that unlike other
159 * chunks, this one can be allocated and mapped in several different
160 * ways and thus often doesn't live in the vmalloc area.
161 */
162struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
163
164/*
165 * Optional reserved chunk. This chunk reserves part of the first
166 * chunk and serves it for reserved allocations. When the reserved
167 * region doesn't exist, the following variable is NULL.
168 */
169struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
170
171DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
172static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
173
174struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
175
176/*
177 * The number of empty populated pages, protected by pcpu_lock.
178 * The reserved chunk doesn't contribute to the count.
179 */
180int pcpu_nr_empty_pop_pages;
181
182/*
183 * The number of populated pages in use by the allocator, protected by
184 * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets
185 * allocated/deallocated, it is allocated/deallocated in all units of a chunk
186 * and increments/decrements this count by 1).
187 */
188static unsigned long pcpu_nr_populated;
189
190/*
191 * Balance work is used to populate or destroy chunks asynchronously. We
192 * try to keep the number of populated free pages between
193 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
194 * empty chunk.
195 */
196static void pcpu_balance_workfn(struct work_struct *work);
197static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
198static bool pcpu_async_enabled __read_mostly;
199static bool pcpu_atomic_alloc_failed;
200
201static void pcpu_schedule_balance_work(void)
202{
203 if (pcpu_async_enabled)
204 schedule_work(&pcpu_balance_work);
205}
206
207/**
208 * pcpu_addr_in_chunk - check if the address is served from this chunk
209 * @chunk: chunk of interest
210 * @addr: percpu address
211 *
212 * RETURNS:
213 * True if the address is served from this chunk.
214 */
215static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
216{
217 void *start_addr, *end_addr;
218
219 if (!chunk)
220 return false;
221
222 start_addr = chunk->base_addr + chunk->start_offset;
223 end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
224 chunk->end_offset;
225
226 return addr >= start_addr && addr < end_addr;
227}
228
229static int __pcpu_size_to_slot(int size)
230{
231 int highbit = fls(size); /* size is in bytes */
232 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
233}
234
235static int pcpu_size_to_slot(int size)
236{
237 if (size == pcpu_unit_size)
238 return pcpu_free_slot;
239 return __pcpu_size_to_slot(size);
240}
241
242static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
243{
244 const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
245
246 if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
247 chunk_md->contig_hint == 0)
248 return 0;
249
250 return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
251}
252
253/* set the pointer to a chunk in a page struct */
254static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
255{
256 page->index = (unsigned long)pcpu;
257}
258
259/* obtain pointer to a chunk from a page struct */
260static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
261{
262 return (struct pcpu_chunk *)page->index;
263}
264
265static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
266{
267 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
268}
269
270static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
271{
272 return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
273}
274
275static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
276 unsigned int cpu, int page_idx)
277{
278 return (unsigned long)chunk->base_addr +
279 pcpu_unit_page_offset(cpu, page_idx);
280}
281
282/*
283 * The following are helper functions to help access bitmaps and convert
284 * between bitmap offsets to address offsets.
285 */
286static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
287{
288 return chunk->alloc_map +
289 (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
290}
291
292static unsigned long pcpu_off_to_block_index(int off)
293{
294 return off / PCPU_BITMAP_BLOCK_BITS;
295}
296
297static unsigned long pcpu_off_to_block_off(int off)
298{
299 return off & (PCPU_BITMAP_BLOCK_BITS - 1);
300}
301
302static unsigned long pcpu_block_off_to_off(int index, int off)
303{
304 return index * PCPU_BITMAP_BLOCK_BITS + off;
305}
306
307/**
308 * pcpu_check_block_hint - check against the contig hint
309 * @block: block of interest
310 * @bits: size of allocation
311 * @align: alignment of area (max PAGE_SIZE)
312 *
313 * Check to see if the allocation can fit in the block's contig hint.
314 * Note, a chunk uses the same hints as a block so this can also check against
315 * the chunk's contig hint.
316 */
317static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits,
318 size_t align)
319{
320 int bit_off = ALIGN(block->contig_hint_start, align) -
321 block->contig_hint_start;
322
323 return bit_off + bits <= block->contig_hint;
324}
325
326/*
327 * pcpu_next_hint - determine which hint to use
328 * @block: block of interest
329 * @alloc_bits: size of allocation
330 *
331 * This determines if we should scan based on the scan_hint or first_free.
332 * In general, we want to scan from first_free to fulfill allocations by
333 * first fit. However, if we know a scan_hint at position scan_hint_start
334 * cannot fulfill an allocation, we can begin scanning from there knowing
335 * the contig_hint will be our fallback.
336 */
337static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
338{
339 /*
340 * The three conditions below determine if we can skip past the
341 * scan_hint. First, does the scan hint exist. Second, is the
342 * contig_hint after the scan_hint (possibly not true iff
343 * contig_hint == scan_hint). Third, is the allocation request
344 * larger than the scan_hint.
345 */
346 if (block->scan_hint &&
347 block->contig_hint_start > block->scan_hint_start &&
348 alloc_bits > block->scan_hint)
349 return block->scan_hint_start + block->scan_hint;
350
351 return block->first_free;
352}
353
354/**
355 * pcpu_next_md_free_region - finds the next hint free area
356 * @chunk: chunk of interest
357 * @bit_off: chunk offset
358 * @bits: size of free area
359 *
360 * Helper function for pcpu_for_each_md_free_region. It checks
361 * block->contig_hint and performs aggregation across blocks to find the
362 * next hint. It modifies bit_off and bits in-place to be consumed in the
363 * loop.
364 */
365static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
366 int *bits)
367{
368 int i = pcpu_off_to_block_index(*bit_off);
369 int block_off = pcpu_off_to_block_off(*bit_off);
370 struct pcpu_block_md *block;
371
372 *bits = 0;
373 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
374 block++, i++) {
375 /* handles contig area across blocks */
376 if (*bits) {
377 *bits += block->left_free;
378 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
379 continue;
380 return;
381 }
382
383 /*
384 * This checks three things. First is there a contig_hint to
385 * check. Second, have we checked this hint before by
386 * comparing the block_off. Third, is this the same as the
387 * right contig hint. In the last case, it spills over into
388 * the next block and should be handled by the contig area
389 * across blocks code.
390 */
391 *bits = block->contig_hint;
392 if (*bits && block->contig_hint_start >= block_off &&
393 *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
394 *bit_off = pcpu_block_off_to_off(i,
395 block->contig_hint_start);
396 return;
397 }
398 /* reset to satisfy the second predicate above */
399 block_off = 0;
400
401 *bits = block->right_free;
402 *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
403 }
404}
405
406/**
407 * pcpu_next_fit_region - finds fit areas for a given allocation request
408 * @chunk: chunk of interest
409 * @alloc_bits: size of allocation
410 * @align: alignment of area (max PAGE_SIZE)
411 * @bit_off: chunk offset
412 * @bits: size of free area
413 *
414 * Finds the next free region that is viable for use with a given size and
415 * alignment. This only returns if there is a valid area to be used for this
416 * allocation. block->first_free is returned if the allocation request fits
417 * within the block to see if the request can be fulfilled prior to the contig
418 * hint.
419 */
420static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
421 int align, int *bit_off, int *bits)
422{
423 int i = pcpu_off_to_block_index(*bit_off);
424 int block_off = pcpu_off_to_block_off(*bit_off);
425 struct pcpu_block_md *block;
426
427 *bits = 0;
428 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
429 block++, i++) {
430 /* handles contig area across blocks */
431 if (*bits) {
432 *bits += block->left_free;
433 if (*bits >= alloc_bits)
434 return;
435 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
436 continue;
437 }
438
439 /* check block->contig_hint */
440 *bits = ALIGN(block->contig_hint_start, align) -
441 block->contig_hint_start;
442 /*
443 * This uses the block offset to determine if this has been
444 * checked in the prior iteration.
445 */
446 if (block->contig_hint &&
447 block->contig_hint_start >= block_off &&
448 block->contig_hint >= *bits + alloc_bits) {
449 int start = pcpu_next_hint(block, alloc_bits);
450
451 *bits += alloc_bits + block->contig_hint_start -
452 start;
453 *bit_off = pcpu_block_off_to_off(i, start);
454 return;
455 }
456 /* reset to satisfy the second predicate above */
457 block_off = 0;
458
459 *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
460 align);
461 *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
462 *bit_off = pcpu_block_off_to_off(i, *bit_off);
463 if (*bits >= alloc_bits)
464 return;
465 }
466
467 /* no valid offsets were found - fail condition */
468 *bit_off = pcpu_chunk_map_bits(chunk);
469}
470
471/*
472 * Metadata free area iterators. These perform aggregation of free areas
473 * based on the metadata blocks and return the offset @bit_off and size in
474 * bits of the free area @bits. pcpu_for_each_fit_region only returns when
475 * a fit is found for the allocation request.
476 */
477#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
478 for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
479 (bit_off) < pcpu_chunk_map_bits((chunk)); \
480 (bit_off) += (bits) + 1, \
481 pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
482
483#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
484 for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
485 &(bits)); \
486 (bit_off) < pcpu_chunk_map_bits((chunk)); \
487 (bit_off) += (bits), \
488 pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
489 &(bits)))
490
491/**
492 * pcpu_mem_zalloc - allocate memory
493 * @size: bytes to allocate
494 * @gfp: allocation flags
495 *
496 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
497 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
498 * This is to facilitate passing through whitelisted flags. The
499 * returned memory is always zeroed.
500 *
501 * RETURNS:
502 * Pointer to the allocated area on success, NULL on failure.
503 */
504static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
505{
506 if (WARN_ON_ONCE(!slab_is_available()))
507 return NULL;
508
509 if (size <= PAGE_SIZE)
510 return kzalloc(size, gfp);
511 else
512 return __vmalloc(size, gfp | __GFP_ZERO);
513}
514
515/**
516 * pcpu_mem_free - free memory
517 * @ptr: memory to free
518 *
519 * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
520 */
521static void pcpu_mem_free(void *ptr)
522{
523 kvfree(ptr);
524}
525
526static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
527 bool move_front)
528{
529 if (chunk != pcpu_reserved_chunk) {
530 if (move_front)
531 list_move(&chunk->list, &pcpu_chunk_lists[slot]);
532 else
533 list_move_tail(&chunk->list, &pcpu_chunk_lists[slot]);
534 }
535}
536
537static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
538{
539 __pcpu_chunk_move(chunk, slot, true);
540}
541
542/**
543 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
544 * @chunk: chunk of interest
545 * @oslot: the previous slot it was on
546 *
547 * This function is called after an allocation or free changed @chunk.
548 * New slot according to the changed state is determined and @chunk is
549 * moved to the slot. Note that the reserved chunk is never put on
550 * chunk slots.
551 *
552 * CONTEXT:
553 * pcpu_lock.
554 */
555static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
556{
557 int nslot = pcpu_chunk_slot(chunk);
558
559 /* leave isolated chunks in-place */
560 if (chunk->isolated)
561 return;
562
563 if (oslot != nslot)
564 __pcpu_chunk_move(chunk, nslot, oslot < nslot);
565}
566
567static void pcpu_isolate_chunk(struct pcpu_chunk *chunk)
568{
569 lockdep_assert_held(&pcpu_lock);
570
571 if (!chunk->isolated) {
572 chunk->isolated = true;
573 pcpu_nr_empty_pop_pages -= chunk->nr_empty_pop_pages;
574 }
575 list_move(&chunk->list, &pcpu_chunk_lists[pcpu_to_depopulate_slot]);
576}
577
578static void pcpu_reintegrate_chunk(struct pcpu_chunk *chunk)
579{
580 lockdep_assert_held(&pcpu_lock);
581
582 if (chunk->isolated) {
583 chunk->isolated = false;
584 pcpu_nr_empty_pop_pages += chunk->nr_empty_pop_pages;
585 pcpu_chunk_relocate(chunk, -1);
586 }
587}
588
589/*
590 * pcpu_update_empty_pages - update empty page counters
591 * @chunk: chunk of interest
592 * @nr: nr of empty pages
593 *
594 * This is used to keep track of the empty pages now based on the premise
595 * a md_block covers a page. The hint update functions recognize if a block
596 * is made full or broken to calculate deltas for keeping track of free pages.
597 */
598static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
599{
600 chunk->nr_empty_pop_pages += nr;
601 if (chunk != pcpu_reserved_chunk && !chunk->isolated)
602 pcpu_nr_empty_pop_pages += nr;
603}
604
605/*
606 * pcpu_region_overlap - determines if two regions overlap
607 * @a: start of first region, inclusive
608 * @b: end of first region, exclusive
609 * @x: start of second region, inclusive
610 * @y: end of second region, exclusive
611 *
612 * This is used to determine if the hint region [a, b) overlaps with the
613 * allocated region [x, y).
614 */
615static inline bool pcpu_region_overlap(int a, int b, int x, int y)
616{
617 return (a < y) && (x < b);
618}
619
620/**
621 * pcpu_block_update - updates a block given a free area
622 * @block: block of interest
623 * @start: start offset in block
624 * @end: end offset in block
625 *
626 * Updates a block given a known free area. The region [start, end) is
627 * expected to be the entirety of the free area within a block. Chooses
628 * the best starting offset if the contig hints are equal.
629 */
630static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
631{
632 int contig = end - start;
633
634 block->first_free = min(block->first_free, start);
635 if (start == 0)
636 block->left_free = contig;
637
638 if (end == block->nr_bits)
639 block->right_free = contig;
640
641 if (contig > block->contig_hint) {
642 /* promote the old contig_hint to be the new scan_hint */
643 if (start > block->contig_hint_start) {
644 if (block->contig_hint > block->scan_hint) {
645 block->scan_hint_start =
646 block->contig_hint_start;
647 block->scan_hint = block->contig_hint;
648 } else if (start < block->scan_hint_start) {
649 /*
650 * The old contig_hint == scan_hint. But, the
651 * new contig is larger so hold the invariant
652 * scan_hint_start < contig_hint_start.
653 */
654 block->scan_hint = 0;
655 }
656 } else {
657 block->scan_hint = 0;
658 }
659 block->contig_hint_start = start;
660 block->contig_hint = contig;
661 } else if (contig == block->contig_hint) {
662 if (block->contig_hint_start &&
663 (!start ||
664 __ffs(start) > __ffs(block->contig_hint_start))) {
665 /* start has a better alignment so use it */
666 block->contig_hint_start = start;
667 if (start < block->scan_hint_start &&
668 block->contig_hint > block->scan_hint)
669 block->scan_hint = 0;
670 } else if (start > block->scan_hint_start ||
671 block->contig_hint > block->scan_hint) {
672 /*
673 * Knowing contig == contig_hint, update the scan_hint
674 * if it is farther than or larger than the current
675 * scan_hint.
676 */
677 block->scan_hint_start = start;
678 block->scan_hint = contig;
679 }
680 } else {
681 /*
682 * The region is smaller than the contig_hint. So only update
683 * the scan_hint if it is larger than or equal and farther than
684 * the current scan_hint.
685 */
686 if ((start < block->contig_hint_start &&
687 (contig > block->scan_hint ||
688 (contig == block->scan_hint &&
689 start > block->scan_hint_start)))) {
690 block->scan_hint_start = start;
691 block->scan_hint = contig;
692 }
693 }
694}
695
696/*
697 * pcpu_block_update_scan - update a block given a free area from a scan
698 * @chunk: chunk of interest
699 * @bit_off: chunk offset
700 * @bits: size of free area
701 *
702 * Finding the final allocation spot first goes through pcpu_find_block_fit()
703 * to find a block that can hold the allocation and then pcpu_alloc_area()
704 * where a scan is used. When allocations require specific alignments,
705 * we can inadvertently create holes which will not be seen in the alloc
706 * or free paths.
707 *
708 * This takes a given free area hole and updates a block as it may change the
709 * scan_hint. We need to scan backwards to ensure we don't miss free bits
710 * from alignment.
711 */
712static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
713 int bits)
714{
715 int s_off = pcpu_off_to_block_off(bit_off);
716 int e_off = s_off + bits;
717 int s_index, l_bit;
718 struct pcpu_block_md *block;
719
720 if (e_off > PCPU_BITMAP_BLOCK_BITS)
721 return;
722
723 s_index = pcpu_off_to_block_index(bit_off);
724 block = chunk->md_blocks + s_index;
725
726 /* scan backwards in case of alignment skipping free bits */
727 l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
728 s_off = (s_off == l_bit) ? 0 : l_bit + 1;
729
730 pcpu_block_update(block, s_off, e_off);
731}
732
733/**
734 * pcpu_chunk_refresh_hint - updates metadata about a chunk
735 * @chunk: chunk of interest
736 * @full_scan: if we should scan from the beginning
737 *
738 * Iterates over the metadata blocks to find the largest contig area.
739 * A full scan can be avoided on the allocation path as this is triggered
740 * if we broke the contig_hint. In doing so, the scan_hint will be before
741 * the contig_hint or after if the scan_hint == contig_hint. This cannot
742 * be prevented on freeing as we want to find the largest area possibly
743 * spanning blocks.
744 */
745static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
746{
747 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
748 int bit_off, bits;
749
750 /* promote scan_hint to contig_hint */
751 if (!full_scan && chunk_md->scan_hint) {
752 bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
753 chunk_md->contig_hint_start = chunk_md->scan_hint_start;
754 chunk_md->contig_hint = chunk_md->scan_hint;
755 chunk_md->scan_hint = 0;
756 } else {
757 bit_off = chunk_md->first_free;
758 chunk_md->contig_hint = 0;
759 }
760
761 bits = 0;
762 pcpu_for_each_md_free_region(chunk, bit_off, bits)
763 pcpu_block_update(chunk_md, bit_off, bit_off + bits);
764}
765
766/**
767 * pcpu_block_refresh_hint
768 * @chunk: chunk of interest
769 * @index: index of the metadata block
770 *
771 * Scans over the block beginning at first_free and updates the block
772 * metadata accordingly.
773 */
774static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
775{
776 struct pcpu_block_md *block = chunk->md_blocks + index;
777 unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
778 unsigned int start, end; /* region start, region end */
779
780 /* promote scan_hint to contig_hint */
781 if (block->scan_hint) {
782 start = block->scan_hint_start + block->scan_hint;
783 block->contig_hint_start = block->scan_hint_start;
784 block->contig_hint = block->scan_hint;
785 block->scan_hint = 0;
786 } else {
787 start = block->first_free;
788 block->contig_hint = 0;
789 }
790
791 block->right_free = 0;
792
793 /* iterate over free areas and update the contig hints */
794 for_each_clear_bitrange_from(start, end, alloc_map, PCPU_BITMAP_BLOCK_BITS)
795 pcpu_block_update(block, start, end);
796}
797
798/**
799 * pcpu_block_update_hint_alloc - update hint on allocation path
800 * @chunk: chunk of interest
801 * @bit_off: chunk offset
802 * @bits: size of request
803 *
804 * Updates metadata for the allocation path. The metadata only has to be
805 * refreshed by a full scan iff the chunk's contig hint is broken. Block level
806 * scans are required if the block's contig hint is broken.
807 */
808static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
809 int bits)
810{
811 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
812 int nr_empty_pages = 0;
813 struct pcpu_block_md *s_block, *e_block, *block;
814 int s_index, e_index; /* block indexes of the freed allocation */
815 int s_off, e_off; /* block offsets of the freed allocation */
816
817 /*
818 * Calculate per block offsets.
819 * The calculation uses an inclusive range, but the resulting offsets
820 * are [start, end). e_index always points to the last block in the
821 * range.
822 */
823 s_index = pcpu_off_to_block_index(bit_off);
824 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
825 s_off = pcpu_off_to_block_off(bit_off);
826 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
827
828 s_block = chunk->md_blocks + s_index;
829 e_block = chunk->md_blocks + e_index;
830
831 /*
832 * Update s_block.
833 */
834 if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
835 nr_empty_pages++;
836
837 /*
838 * block->first_free must be updated if the allocation takes its place.
839 * If the allocation breaks the contig_hint, a scan is required to
840 * restore this hint.
841 */
842 if (s_off == s_block->first_free)
843 s_block->first_free = find_next_zero_bit(
844 pcpu_index_alloc_map(chunk, s_index),
845 PCPU_BITMAP_BLOCK_BITS,
846 s_off + bits);
847
848 if (pcpu_region_overlap(s_block->scan_hint_start,
849 s_block->scan_hint_start + s_block->scan_hint,
850 s_off,
851 s_off + bits))
852 s_block->scan_hint = 0;
853
854 if (pcpu_region_overlap(s_block->contig_hint_start,
855 s_block->contig_hint_start +
856 s_block->contig_hint,
857 s_off,
858 s_off + bits)) {
859 /* block contig hint is broken - scan to fix it */
860 if (!s_off)
861 s_block->left_free = 0;
862 pcpu_block_refresh_hint(chunk, s_index);
863 } else {
864 /* update left and right contig manually */
865 s_block->left_free = min(s_block->left_free, s_off);
866 if (s_index == e_index)
867 s_block->right_free = min_t(int, s_block->right_free,
868 PCPU_BITMAP_BLOCK_BITS - e_off);
869 else
870 s_block->right_free = 0;
871 }
872
873 /*
874 * Update e_block.
875 */
876 if (s_index != e_index) {
877 if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
878 nr_empty_pages++;
879
880 /*
881 * When the allocation is across blocks, the end is along
882 * the left part of the e_block.
883 */
884 e_block->first_free = find_next_zero_bit(
885 pcpu_index_alloc_map(chunk, e_index),
886 PCPU_BITMAP_BLOCK_BITS, e_off);
887
888 if (e_off == PCPU_BITMAP_BLOCK_BITS) {
889 /* reset the block */
890 e_block++;
891 } else {
892 if (e_off > e_block->scan_hint_start)
893 e_block->scan_hint = 0;
894
895 e_block->left_free = 0;
896 if (e_off > e_block->contig_hint_start) {
897 /* contig hint is broken - scan to fix it */
898 pcpu_block_refresh_hint(chunk, e_index);
899 } else {
900 e_block->right_free =
901 min_t(int, e_block->right_free,
902 PCPU_BITMAP_BLOCK_BITS - e_off);
903 }
904 }
905
906 /* update in-between md_blocks */
907 nr_empty_pages += (e_index - s_index - 1);
908 for (block = s_block + 1; block < e_block; block++) {
909 block->scan_hint = 0;
910 block->contig_hint = 0;
911 block->left_free = 0;
912 block->right_free = 0;
913 }
914 }
915
916 /*
917 * If the allocation is not atomic, some blocks may not be
918 * populated with pages, while we account it here. The number
919 * of pages will be added back with pcpu_chunk_populated()
920 * when populating pages.
921 */
922 if (nr_empty_pages)
923 pcpu_update_empty_pages(chunk, -nr_empty_pages);
924
925 if (pcpu_region_overlap(chunk_md->scan_hint_start,
926 chunk_md->scan_hint_start +
927 chunk_md->scan_hint,
928 bit_off,
929 bit_off + bits))
930 chunk_md->scan_hint = 0;
931
932 /*
933 * The only time a full chunk scan is required is if the chunk
934 * contig hint is broken. Otherwise, it means a smaller space
935 * was used and therefore the chunk contig hint is still correct.
936 */
937 if (pcpu_region_overlap(chunk_md->contig_hint_start,
938 chunk_md->contig_hint_start +
939 chunk_md->contig_hint,
940 bit_off,
941 bit_off + bits))
942 pcpu_chunk_refresh_hint(chunk, false);
943}
944
945/**
946 * pcpu_block_update_hint_free - updates the block hints on the free path
947 * @chunk: chunk of interest
948 * @bit_off: chunk offset
949 * @bits: size of request
950 *
951 * Updates metadata for the allocation path. This avoids a blind block
952 * refresh by making use of the block contig hints. If this fails, it scans
953 * forward and backward to determine the extent of the free area. This is
954 * capped at the boundary of blocks.
955 *
956 * A chunk update is triggered if a page becomes free, a block becomes free,
957 * or the free spans across blocks. This tradeoff is to minimize iterating
958 * over the block metadata to update chunk_md->contig_hint.
959 * chunk_md->contig_hint may be off by up to a page, but it will never be more
960 * than the available space. If the contig hint is contained in one block, it
961 * will be accurate.
962 */
963static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
964 int bits)
965{
966 int nr_empty_pages = 0;
967 struct pcpu_block_md *s_block, *e_block, *block;
968 int s_index, e_index; /* block indexes of the freed allocation */
969 int s_off, e_off; /* block offsets of the freed allocation */
970 int start, end; /* start and end of the whole free area */
971
972 /*
973 * Calculate per block offsets.
974 * The calculation uses an inclusive range, but the resulting offsets
975 * are [start, end). e_index always points to the last block in the
976 * range.
977 */
978 s_index = pcpu_off_to_block_index(bit_off);
979 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
980 s_off = pcpu_off_to_block_off(bit_off);
981 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
982
983 s_block = chunk->md_blocks + s_index;
984 e_block = chunk->md_blocks + e_index;
985
986 /*
987 * Check if the freed area aligns with the block->contig_hint.
988 * If it does, then the scan to find the beginning/end of the
989 * larger free area can be avoided.
990 *
991 * start and end refer to beginning and end of the free area
992 * within each their respective blocks. This is not necessarily
993 * the entire free area as it may span blocks past the beginning
994 * or end of the block.
995 */
996 start = s_off;
997 if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
998 start = s_block->contig_hint_start;
999 } else {
1000 /*
1001 * Scan backwards to find the extent of the free area.
1002 * find_last_bit returns the starting bit, so if the start bit
1003 * is returned, that means there was no last bit and the
1004 * remainder of the chunk is free.
1005 */
1006 int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
1007 start);
1008 start = (start == l_bit) ? 0 : l_bit + 1;
1009 }
1010
1011 end = e_off;
1012 if (e_off == e_block->contig_hint_start)
1013 end = e_block->contig_hint_start + e_block->contig_hint;
1014 else
1015 end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
1016 PCPU_BITMAP_BLOCK_BITS, end);
1017
1018 /* update s_block */
1019 e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
1020 if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
1021 nr_empty_pages++;
1022 pcpu_block_update(s_block, start, e_off);
1023
1024 /* freeing in the same block */
1025 if (s_index != e_index) {
1026 /* update e_block */
1027 if (end == PCPU_BITMAP_BLOCK_BITS)
1028 nr_empty_pages++;
1029 pcpu_block_update(e_block, 0, end);
1030
1031 /* reset md_blocks in the middle */
1032 nr_empty_pages += (e_index - s_index - 1);
1033 for (block = s_block + 1; block < e_block; block++) {
1034 block->first_free = 0;
1035 block->scan_hint = 0;
1036 block->contig_hint_start = 0;
1037 block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
1038 block->left_free = PCPU_BITMAP_BLOCK_BITS;
1039 block->right_free = PCPU_BITMAP_BLOCK_BITS;
1040 }
1041 }
1042
1043 if (nr_empty_pages)
1044 pcpu_update_empty_pages(chunk, nr_empty_pages);
1045
1046 /*
1047 * Refresh chunk metadata when the free makes a block free or spans
1048 * across blocks. The contig_hint may be off by up to a page, but if
1049 * the contig_hint is contained in a block, it will be accurate with
1050 * the else condition below.
1051 */
1052 if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1053 pcpu_chunk_refresh_hint(chunk, true);
1054 else
1055 pcpu_block_update(&chunk->chunk_md,
1056 pcpu_block_off_to_off(s_index, start),
1057 end);
1058}
1059
1060/**
1061 * pcpu_is_populated - determines if the region is populated
1062 * @chunk: chunk of interest
1063 * @bit_off: chunk offset
1064 * @bits: size of area
1065 * @next_off: return value for the next offset to start searching
1066 *
1067 * For atomic allocations, check if the backing pages are populated.
1068 *
1069 * RETURNS:
1070 * Bool if the backing pages are populated.
1071 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1072 */
1073static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1074 int *next_off)
1075{
1076 unsigned int start, end;
1077
1078 start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1079 end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1080
1081 start = find_next_zero_bit(chunk->populated, end, start);
1082 if (start >= end)
1083 return true;
1084
1085 end = find_next_bit(chunk->populated, end, start + 1);
1086
1087 *next_off = end * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1088 return false;
1089}
1090
1091/**
1092 * pcpu_find_block_fit - finds the block index to start searching
1093 * @chunk: chunk of interest
1094 * @alloc_bits: size of request in allocation units
1095 * @align: alignment of area (max PAGE_SIZE bytes)
1096 * @pop_only: use populated regions only
1097 *
1098 * Given a chunk and an allocation spec, find the offset to begin searching
1099 * for a free region. This iterates over the bitmap metadata blocks to
1100 * find an offset that will be guaranteed to fit the requirements. It is
1101 * not quite first fit as if the allocation does not fit in the contig hint
1102 * of a block or chunk, it is skipped. This errs on the side of caution
1103 * to prevent excess iteration. Poor alignment can cause the allocator to
1104 * skip over blocks and chunks that have valid free areas.
1105 *
1106 * RETURNS:
1107 * The offset in the bitmap to begin searching.
1108 * -1 if no offset is found.
1109 */
1110static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1111 size_t align, bool pop_only)
1112{
1113 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1114 int bit_off, bits, next_off;
1115
1116 /*
1117 * This is an optimization to prevent scanning by assuming if the
1118 * allocation cannot fit in the global hint, there is memory pressure
1119 * and creating a new chunk would happen soon.
1120 */
1121 if (!pcpu_check_block_hint(chunk_md, alloc_bits, align))
1122 return -1;
1123
1124 bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1125 bits = 0;
1126 pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1127 if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1128 &next_off))
1129 break;
1130
1131 bit_off = next_off;
1132 bits = 0;
1133 }
1134
1135 if (bit_off == pcpu_chunk_map_bits(chunk))
1136 return -1;
1137
1138 return bit_off;
1139}
1140
1141/*
1142 * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1143 * @map: the address to base the search on
1144 * @size: the bitmap size in bits
1145 * @start: the bitnumber to start searching at
1146 * @nr: the number of zeroed bits we're looking for
1147 * @align_mask: alignment mask for zero area
1148 * @largest_off: offset of the largest area skipped
1149 * @largest_bits: size of the largest area skipped
1150 *
1151 * The @align_mask should be one less than a power of 2.
1152 *
1153 * This is a modified version of bitmap_find_next_zero_area_off() to remember
1154 * the largest area that was skipped. This is imperfect, but in general is
1155 * good enough. The largest remembered region is the largest failed region
1156 * seen. This does not include anything we possibly skipped due to alignment.
1157 * pcpu_block_update_scan() does scan backwards to try and recover what was
1158 * lost to alignment. While this can cause scanning to miss earlier possible
1159 * free areas, smaller allocations will eventually fill those holes.
1160 */
1161static unsigned long pcpu_find_zero_area(unsigned long *map,
1162 unsigned long size,
1163 unsigned long start,
1164 unsigned long nr,
1165 unsigned long align_mask,
1166 unsigned long *largest_off,
1167 unsigned long *largest_bits)
1168{
1169 unsigned long index, end, i, area_off, area_bits;
1170again:
1171 index = find_next_zero_bit(map, size, start);
1172
1173 /* Align allocation */
1174 index = __ALIGN_MASK(index, align_mask);
1175 area_off = index;
1176
1177 end = index + nr;
1178 if (end > size)
1179 return end;
1180 i = find_next_bit(map, end, index);
1181 if (i < end) {
1182 area_bits = i - area_off;
1183 /* remember largest unused area with best alignment */
1184 if (area_bits > *largest_bits ||
1185 (area_bits == *largest_bits && *largest_off &&
1186 (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1187 *largest_off = area_off;
1188 *largest_bits = area_bits;
1189 }
1190
1191 start = i + 1;
1192 goto again;
1193 }
1194 return index;
1195}
1196
1197/**
1198 * pcpu_alloc_area - allocates an area from a pcpu_chunk
1199 * @chunk: chunk of interest
1200 * @alloc_bits: size of request in allocation units
1201 * @align: alignment of area (max PAGE_SIZE)
1202 * @start: bit_off to start searching
1203 *
1204 * This function takes in a @start offset to begin searching to fit an
1205 * allocation of @alloc_bits with alignment @align. It needs to scan
1206 * the allocation map because if it fits within the block's contig hint,
1207 * @start will be block->first_free. This is an attempt to fill the
1208 * allocation prior to breaking the contig hint. The allocation and
1209 * boundary maps are updated accordingly if it confirms a valid
1210 * free area.
1211 *
1212 * RETURNS:
1213 * Allocated addr offset in @chunk on success.
1214 * -1 if no matching area is found.
1215 */
1216static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1217 size_t align, int start)
1218{
1219 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1220 size_t align_mask = (align) ? (align - 1) : 0;
1221 unsigned long area_off = 0, area_bits = 0;
1222 int bit_off, end, oslot;
1223
1224 lockdep_assert_held(&pcpu_lock);
1225
1226 oslot = pcpu_chunk_slot(chunk);
1227
1228 /*
1229 * Search to find a fit.
1230 */
1231 end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1232 pcpu_chunk_map_bits(chunk));
1233 bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1234 align_mask, &area_off, &area_bits);
1235 if (bit_off >= end)
1236 return -1;
1237
1238 if (area_bits)
1239 pcpu_block_update_scan(chunk, area_off, area_bits);
1240
1241 /* update alloc map */
1242 bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1243
1244 /* update boundary map */
1245 set_bit(bit_off, chunk->bound_map);
1246 bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1247 set_bit(bit_off + alloc_bits, chunk->bound_map);
1248
1249 chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1250
1251 /* update first free bit */
1252 if (bit_off == chunk_md->first_free)
1253 chunk_md->first_free = find_next_zero_bit(
1254 chunk->alloc_map,
1255 pcpu_chunk_map_bits(chunk),
1256 bit_off + alloc_bits);
1257
1258 pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1259
1260 pcpu_chunk_relocate(chunk, oslot);
1261
1262 return bit_off * PCPU_MIN_ALLOC_SIZE;
1263}
1264
1265/**
1266 * pcpu_free_area - frees the corresponding offset
1267 * @chunk: chunk of interest
1268 * @off: addr offset into chunk
1269 *
1270 * This function determines the size of an allocation to free using
1271 * the boundary bitmap and clears the allocation map.
1272 *
1273 * RETURNS:
1274 * Number of freed bytes.
1275 */
1276static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
1277{
1278 struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1279 int bit_off, bits, end, oslot, freed;
1280
1281 lockdep_assert_held(&pcpu_lock);
1282 pcpu_stats_area_dealloc(chunk);
1283
1284 oslot = pcpu_chunk_slot(chunk);
1285
1286 bit_off = off / PCPU_MIN_ALLOC_SIZE;
1287
1288 /* find end index */
1289 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1290 bit_off + 1);
1291 bits = end - bit_off;
1292 bitmap_clear(chunk->alloc_map, bit_off, bits);
1293
1294 freed = bits * PCPU_MIN_ALLOC_SIZE;
1295
1296 /* update metadata */
1297 chunk->free_bytes += freed;
1298
1299 /* update first free bit */
1300 chunk_md->first_free = min(chunk_md->first_free, bit_off);
1301
1302 pcpu_block_update_hint_free(chunk, bit_off, bits);
1303
1304 pcpu_chunk_relocate(chunk, oslot);
1305
1306 return freed;
1307}
1308
1309static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1310{
1311 block->scan_hint = 0;
1312 block->contig_hint = nr_bits;
1313 block->left_free = nr_bits;
1314 block->right_free = nr_bits;
1315 block->first_free = 0;
1316 block->nr_bits = nr_bits;
1317}
1318
1319static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1320{
1321 struct pcpu_block_md *md_block;
1322
1323 /* init the chunk's block */
1324 pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1325
1326 for (md_block = chunk->md_blocks;
1327 md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1328 md_block++)
1329 pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1330}
1331
1332/**
1333 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1334 * @tmp_addr: the start of the region served
1335 * @map_size: size of the region served
1336 *
1337 * This is responsible for creating the chunks that serve the first chunk. The
1338 * base_addr is page aligned down of @tmp_addr while the region end is page
1339 * aligned up. Offsets are kept track of to determine the region served. All
1340 * this is done to appease the bitmap allocator in avoiding partial blocks.
1341 *
1342 * RETURNS:
1343 * Chunk serving the region at @tmp_addr of @map_size.
1344 */
1345static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1346 int map_size)
1347{
1348 struct pcpu_chunk *chunk;
1349 unsigned long aligned_addr;
1350 int start_offset, offset_bits, region_size, region_bits;
1351 size_t alloc_size;
1352
1353 /* region calculations */
1354 aligned_addr = tmp_addr & PAGE_MASK;
1355
1356 start_offset = tmp_addr - aligned_addr;
1357 region_size = ALIGN(start_offset + map_size, PAGE_SIZE);
1358
1359 /* allocate chunk */
1360 alloc_size = struct_size(chunk, populated,
1361 BITS_TO_LONGS(region_size >> PAGE_SHIFT));
1362 chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1363 if (!chunk)
1364 panic("%s: Failed to allocate %zu bytes\n", __func__,
1365 alloc_size);
1366
1367 INIT_LIST_HEAD(&chunk->list);
1368
1369 chunk->base_addr = (void *)aligned_addr;
1370 chunk->start_offset = start_offset;
1371 chunk->end_offset = region_size - chunk->start_offset - map_size;
1372
1373 chunk->nr_pages = region_size >> PAGE_SHIFT;
1374 region_bits = pcpu_chunk_map_bits(chunk);
1375
1376 alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1377 chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1378 if (!chunk->alloc_map)
1379 panic("%s: Failed to allocate %zu bytes\n", __func__,
1380 alloc_size);
1381
1382 alloc_size =
1383 BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1384 chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1385 if (!chunk->bound_map)
1386 panic("%s: Failed to allocate %zu bytes\n", __func__,
1387 alloc_size);
1388
1389 alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1390 chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1391 if (!chunk->md_blocks)
1392 panic("%s: Failed to allocate %zu bytes\n", __func__,
1393 alloc_size);
1394
1395#ifdef CONFIG_MEMCG_KMEM
1396 /* first chunk is free to use */
1397 chunk->obj_cgroups = NULL;
1398#endif
1399 pcpu_init_md_blocks(chunk);
1400
1401 /* manage populated page bitmap */
1402 chunk->immutable = true;
1403 bitmap_fill(chunk->populated, chunk->nr_pages);
1404 chunk->nr_populated = chunk->nr_pages;
1405 chunk->nr_empty_pop_pages = chunk->nr_pages;
1406
1407 chunk->free_bytes = map_size;
1408
1409 if (chunk->start_offset) {
1410 /* hide the beginning of the bitmap */
1411 offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1412 bitmap_set(chunk->alloc_map, 0, offset_bits);
1413 set_bit(0, chunk->bound_map);
1414 set_bit(offset_bits, chunk->bound_map);
1415
1416 chunk->chunk_md.first_free = offset_bits;
1417
1418 pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1419 }
1420
1421 if (chunk->end_offset) {
1422 /* hide the end of the bitmap */
1423 offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1424 bitmap_set(chunk->alloc_map,
1425 pcpu_chunk_map_bits(chunk) - offset_bits,
1426 offset_bits);
1427 set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1428 chunk->bound_map);
1429 set_bit(region_bits, chunk->bound_map);
1430
1431 pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1432 - offset_bits, offset_bits);
1433 }
1434
1435 return chunk;
1436}
1437
1438static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
1439{
1440 struct pcpu_chunk *chunk;
1441 int region_bits;
1442
1443 chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1444 if (!chunk)
1445 return NULL;
1446
1447 INIT_LIST_HEAD(&chunk->list);
1448 chunk->nr_pages = pcpu_unit_pages;
1449 region_bits = pcpu_chunk_map_bits(chunk);
1450
1451 chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1452 sizeof(chunk->alloc_map[0]), gfp);
1453 if (!chunk->alloc_map)
1454 goto alloc_map_fail;
1455
1456 chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1457 sizeof(chunk->bound_map[0]), gfp);
1458 if (!chunk->bound_map)
1459 goto bound_map_fail;
1460
1461 chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1462 sizeof(chunk->md_blocks[0]), gfp);
1463 if (!chunk->md_blocks)
1464 goto md_blocks_fail;
1465
1466#ifdef CONFIG_MEMCG_KMEM
1467 if (!mem_cgroup_kmem_disabled()) {
1468 chunk->obj_cgroups =
1469 pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
1470 sizeof(struct obj_cgroup *), gfp);
1471 if (!chunk->obj_cgroups)
1472 goto objcg_fail;
1473 }
1474#endif
1475
1476 pcpu_init_md_blocks(chunk);
1477
1478 /* init metadata */
1479 chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1480
1481 return chunk;
1482
1483#ifdef CONFIG_MEMCG_KMEM
1484objcg_fail:
1485 pcpu_mem_free(chunk->md_blocks);
1486#endif
1487md_blocks_fail:
1488 pcpu_mem_free(chunk->bound_map);
1489bound_map_fail:
1490 pcpu_mem_free(chunk->alloc_map);
1491alloc_map_fail:
1492 pcpu_mem_free(chunk);
1493
1494 return NULL;
1495}
1496
1497static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1498{
1499 if (!chunk)
1500 return;
1501#ifdef CONFIG_MEMCG_KMEM
1502 pcpu_mem_free(chunk->obj_cgroups);
1503#endif
1504 pcpu_mem_free(chunk->md_blocks);
1505 pcpu_mem_free(chunk->bound_map);
1506 pcpu_mem_free(chunk->alloc_map);
1507 pcpu_mem_free(chunk);
1508}
1509
1510/**
1511 * pcpu_chunk_populated - post-population bookkeeping
1512 * @chunk: pcpu_chunk which got populated
1513 * @page_start: the start page
1514 * @page_end: the end page
1515 *
1516 * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1517 * the bookkeeping information accordingly. Must be called after each
1518 * successful population.
1519 */
1520static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1521 int page_end)
1522{
1523 int nr = page_end - page_start;
1524
1525 lockdep_assert_held(&pcpu_lock);
1526
1527 bitmap_set(chunk->populated, page_start, nr);
1528 chunk->nr_populated += nr;
1529 pcpu_nr_populated += nr;
1530
1531 pcpu_update_empty_pages(chunk, nr);
1532}
1533
1534/**
1535 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1536 * @chunk: pcpu_chunk which got depopulated
1537 * @page_start: the start page
1538 * @page_end: the end page
1539 *
1540 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1541 * Update the bookkeeping information accordingly. Must be called after
1542 * each successful depopulation.
1543 */
1544static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1545 int page_start, int page_end)
1546{
1547 int nr = page_end - page_start;
1548
1549 lockdep_assert_held(&pcpu_lock);
1550
1551 bitmap_clear(chunk->populated, page_start, nr);
1552 chunk->nr_populated -= nr;
1553 pcpu_nr_populated -= nr;
1554
1555 pcpu_update_empty_pages(chunk, -nr);
1556}
1557
1558/*
1559 * Chunk management implementation.
1560 *
1561 * To allow different implementations, chunk alloc/free and
1562 * [de]population are implemented in a separate file which is pulled
1563 * into this file and compiled together. The following functions
1564 * should be implemented.
1565 *
1566 * pcpu_populate_chunk - populate the specified range of a chunk
1567 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1568 * pcpu_post_unmap_tlb_flush - flush tlb for the specified range of a chunk
1569 * pcpu_create_chunk - create a new chunk
1570 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1571 * pcpu_addr_to_page - translate address to physical address
1572 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1573 */
1574static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1575 int page_start, int page_end, gfp_t gfp);
1576static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1577 int page_start, int page_end);
1578static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
1579 int page_start, int page_end);
1580static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
1581static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1582static struct page *pcpu_addr_to_page(void *addr);
1583static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1584
1585#ifdef CONFIG_NEED_PER_CPU_KM
1586#include "percpu-km.c"
1587#else
1588#include "percpu-vm.c"
1589#endif
1590
1591/**
1592 * pcpu_chunk_addr_search - determine chunk containing specified address
1593 * @addr: address for which the chunk needs to be determined.
1594 *
1595 * This is an internal function that handles all but static allocations.
1596 * Static percpu address values should never be passed into the allocator.
1597 *
1598 * RETURNS:
1599 * The address of the found chunk.
1600 */
1601static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1602{
1603 /* is it in the dynamic region (first chunk)? */
1604 if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1605 return pcpu_first_chunk;
1606
1607 /* is it in the reserved region? */
1608 if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1609 return pcpu_reserved_chunk;
1610
1611 /*
1612 * The address is relative to unit0 which might be unused and
1613 * thus unmapped. Offset the address to the unit space of the
1614 * current processor before looking it up in the vmalloc
1615 * space. Note that any possible cpu id can be used here, so
1616 * there's no need to worry about preemption or cpu hotplug.
1617 */
1618 addr += pcpu_unit_offsets[raw_smp_processor_id()];
1619 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1620}
1621
1622#ifdef CONFIG_MEMCG_KMEM
1623static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
1624 struct obj_cgroup **objcgp)
1625{
1626 struct obj_cgroup *objcg;
1627
1628 if (!memcg_kmem_online() || !(gfp & __GFP_ACCOUNT))
1629 return true;
1630
1631 objcg = current_obj_cgroup();
1632 if (!objcg)
1633 return true;
1634
1635 if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size)))
1636 return false;
1637
1638 *objcgp = objcg;
1639 return true;
1640}
1641
1642static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1643 struct pcpu_chunk *chunk, int off,
1644 size_t size)
1645{
1646 if (!objcg)
1647 return;
1648
1649 if (likely(chunk && chunk->obj_cgroups)) {
1650 obj_cgroup_get(objcg);
1651 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
1652
1653 rcu_read_lock();
1654 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1655 pcpu_obj_full_size(size));
1656 rcu_read_unlock();
1657 } else {
1658 obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
1659 }
1660}
1661
1662static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1663{
1664 struct obj_cgroup *objcg;
1665
1666 if (unlikely(!chunk->obj_cgroups))
1667 return;
1668
1669 objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
1670 if (!objcg)
1671 return;
1672 chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
1673
1674 obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
1675
1676 rcu_read_lock();
1677 mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1678 -pcpu_obj_full_size(size));
1679 rcu_read_unlock();
1680
1681 obj_cgroup_put(objcg);
1682}
1683
1684#else /* CONFIG_MEMCG_KMEM */
1685static bool
1686pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
1687{
1688 return true;
1689}
1690
1691static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1692 struct pcpu_chunk *chunk, int off,
1693 size_t size)
1694{
1695}
1696
1697static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1698{
1699}
1700#endif /* CONFIG_MEMCG_KMEM */
1701
1702/**
1703 * pcpu_alloc - the percpu allocator
1704 * @size: size of area to allocate in bytes
1705 * @align: alignment of area (max PAGE_SIZE)
1706 * @reserved: allocate from the reserved chunk if available
1707 * @gfp: allocation flags
1708 *
1709 * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1710 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1711 * then no warning will be triggered on invalid or failed allocation
1712 * requests.
1713 *
1714 * RETURNS:
1715 * Percpu pointer to the allocated area on success, NULL on failure.
1716 */
1717static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1718 gfp_t gfp)
1719{
1720 gfp_t pcpu_gfp;
1721 bool is_atomic;
1722 bool do_warn;
1723 struct obj_cgroup *objcg = NULL;
1724 static int warn_limit = 10;
1725 struct pcpu_chunk *chunk, *next;
1726 const char *err;
1727 int slot, off, cpu, ret;
1728 unsigned long flags;
1729 void __percpu *ptr;
1730 size_t bits, bit_align;
1731
1732 gfp = current_gfp_context(gfp);
1733 /* whitelisted flags that can be passed to the backing allocators */
1734 pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1735 is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1736 do_warn = !(gfp & __GFP_NOWARN);
1737
1738 /*
1739 * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1740 * therefore alignment must be a minimum of that many bytes.
1741 * An allocation may have internal fragmentation from rounding up
1742 * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1743 */
1744 if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1745 align = PCPU_MIN_ALLOC_SIZE;
1746
1747 size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1748 bits = size >> PCPU_MIN_ALLOC_SHIFT;
1749 bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1750
1751 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1752 !is_power_of_2(align))) {
1753 WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1754 size, align);
1755 return NULL;
1756 }
1757
1758 if (unlikely(!pcpu_memcg_pre_alloc_hook(size, gfp, &objcg)))
1759 return NULL;
1760
1761 if (!is_atomic) {
1762 /*
1763 * pcpu_balance_workfn() allocates memory under this mutex,
1764 * and it may wait for memory reclaim. Allow current task
1765 * to become OOM victim, in case of memory pressure.
1766 */
1767 if (gfp & __GFP_NOFAIL) {
1768 mutex_lock(&pcpu_alloc_mutex);
1769 } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
1770 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1771 return NULL;
1772 }
1773 }
1774
1775 spin_lock_irqsave(&pcpu_lock, flags);
1776
1777 /* serve reserved allocations from the reserved chunk if available */
1778 if (reserved && pcpu_reserved_chunk) {
1779 chunk = pcpu_reserved_chunk;
1780
1781 off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1782 if (off < 0) {
1783 err = "alloc from reserved chunk failed";
1784 goto fail_unlock;
1785 }
1786
1787 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1788 if (off >= 0)
1789 goto area_found;
1790
1791 err = "alloc from reserved chunk failed";
1792 goto fail_unlock;
1793 }
1794
1795restart:
1796 /* search through normal chunks */
1797 for (slot = pcpu_size_to_slot(size); slot <= pcpu_free_slot; slot++) {
1798 list_for_each_entry_safe(chunk, next, &pcpu_chunk_lists[slot],
1799 list) {
1800 off = pcpu_find_block_fit(chunk, bits, bit_align,
1801 is_atomic);
1802 if (off < 0) {
1803 if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1804 pcpu_chunk_move(chunk, 0);
1805 continue;
1806 }
1807
1808 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1809 if (off >= 0) {
1810 pcpu_reintegrate_chunk(chunk);
1811 goto area_found;
1812 }
1813 }
1814 }
1815
1816 spin_unlock_irqrestore(&pcpu_lock, flags);
1817
1818 if (is_atomic) {
1819 err = "atomic alloc failed, no space left";
1820 goto fail;
1821 }
1822
1823 /* No space left. Create a new chunk. */
1824 if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
1825 chunk = pcpu_create_chunk(pcpu_gfp);
1826 if (!chunk) {
1827 err = "failed to allocate new chunk";
1828 goto fail;
1829 }
1830
1831 spin_lock_irqsave(&pcpu_lock, flags);
1832 pcpu_chunk_relocate(chunk, -1);
1833 } else {
1834 spin_lock_irqsave(&pcpu_lock, flags);
1835 }
1836
1837 goto restart;
1838
1839area_found:
1840 pcpu_stats_area_alloc(chunk, size);
1841 spin_unlock_irqrestore(&pcpu_lock, flags);
1842
1843 /* populate if not all pages are already there */
1844 if (!is_atomic) {
1845 unsigned int page_end, rs, re;
1846
1847 rs = PFN_DOWN(off);
1848 page_end = PFN_UP(off + size);
1849
1850 for_each_clear_bitrange_from(rs, re, chunk->populated, page_end) {
1851 WARN_ON(chunk->immutable);
1852
1853 ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1854
1855 spin_lock_irqsave(&pcpu_lock, flags);
1856 if (ret) {
1857 pcpu_free_area(chunk, off);
1858 err = "failed to populate";
1859 goto fail_unlock;
1860 }
1861 pcpu_chunk_populated(chunk, rs, re);
1862 spin_unlock_irqrestore(&pcpu_lock, flags);
1863 }
1864
1865 mutex_unlock(&pcpu_alloc_mutex);
1866 }
1867
1868 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1869 pcpu_schedule_balance_work();
1870
1871 /* clear the areas and return address relative to base address */
1872 for_each_possible_cpu(cpu)
1873 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1874
1875 ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1876 kmemleak_alloc_percpu(ptr, size, gfp);
1877
1878 trace_percpu_alloc_percpu(_RET_IP_, reserved, is_atomic, size, align,
1879 chunk->base_addr, off, ptr,
1880 pcpu_obj_full_size(size), gfp);
1881
1882 pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
1883
1884 return ptr;
1885
1886fail_unlock:
1887 spin_unlock_irqrestore(&pcpu_lock, flags);
1888fail:
1889 trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1890
1891 if (do_warn && warn_limit) {
1892 pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1893 size, align, is_atomic, err);
1894 if (!is_atomic)
1895 dump_stack();
1896 if (!--warn_limit)
1897 pr_info("limit reached, disable warning\n");
1898 }
1899
1900 if (is_atomic) {
1901 /* see the flag handling in pcpu_balance_workfn() */
1902 pcpu_atomic_alloc_failed = true;
1903 pcpu_schedule_balance_work();
1904 } else {
1905 mutex_unlock(&pcpu_alloc_mutex);
1906 }
1907
1908 pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1909
1910 return NULL;
1911}
1912
1913/**
1914 * __alloc_percpu_gfp - allocate dynamic percpu area
1915 * @size: size of area to allocate in bytes
1916 * @align: alignment of area (max PAGE_SIZE)
1917 * @gfp: allocation flags
1918 *
1919 * Allocate zero-filled percpu area of @size bytes aligned at @align. If
1920 * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1921 * be called from any context but is a lot more likely to fail. If @gfp
1922 * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1923 * allocation requests.
1924 *
1925 * RETURNS:
1926 * Percpu pointer to the allocated area on success, NULL on failure.
1927 */
1928void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1929{
1930 return pcpu_alloc(size, align, false, gfp);
1931}
1932EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1933
1934/**
1935 * __alloc_percpu - allocate dynamic percpu area
1936 * @size: size of area to allocate in bytes
1937 * @align: alignment of area (max PAGE_SIZE)
1938 *
1939 * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1940 */
1941void __percpu *__alloc_percpu(size_t size, size_t align)
1942{
1943 return pcpu_alloc(size, align, false, GFP_KERNEL);
1944}
1945EXPORT_SYMBOL_GPL(__alloc_percpu);
1946
1947/**
1948 * __alloc_reserved_percpu - allocate reserved percpu area
1949 * @size: size of area to allocate in bytes
1950 * @align: alignment of area (max PAGE_SIZE)
1951 *
1952 * Allocate zero-filled percpu area of @size bytes aligned at @align
1953 * from reserved percpu area if arch has set it up; otherwise,
1954 * allocation is served from the same dynamic area. Might sleep.
1955 * Might trigger writeouts.
1956 *
1957 * CONTEXT:
1958 * Does GFP_KERNEL allocation.
1959 *
1960 * RETURNS:
1961 * Percpu pointer to the allocated area on success, NULL on failure.
1962 */
1963void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1964{
1965 return pcpu_alloc(size, align, true, GFP_KERNEL);
1966}
1967
1968/**
1969 * pcpu_balance_free - manage the amount of free chunks
1970 * @empty_only: free chunks only if there are no populated pages
1971 *
1972 * If empty_only is %false, reclaim all fully free chunks regardless of the
1973 * number of populated pages. Otherwise, only reclaim chunks that have no
1974 * populated pages.
1975 *
1976 * CONTEXT:
1977 * pcpu_lock (can be dropped temporarily)
1978 */
1979static void pcpu_balance_free(bool empty_only)
1980{
1981 LIST_HEAD(to_free);
1982 struct list_head *free_head = &pcpu_chunk_lists[pcpu_free_slot];
1983 struct pcpu_chunk *chunk, *next;
1984
1985 lockdep_assert_held(&pcpu_lock);
1986
1987 /*
1988 * There's no reason to keep around multiple unused chunks and VM
1989 * areas can be scarce. Destroy all free chunks except for one.
1990 */
1991 list_for_each_entry_safe(chunk, next, free_head, list) {
1992 WARN_ON(chunk->immutable);
1993
1994 /* spare the first one */
1995 if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1996 continue;
1997
1998 if (!empty_only || chunk->nr_empty_pop_pages == 0)
1999 list_move(&chunk->list, &to_free);
2000 }
2001
2002 if (list_empty(&to_free))
2003 return;
2004
2005 spin_unlock_irq(&pcpu_lock);
2006 list_for_each_entry_safe(chunk, next, &to_free, list) {
2007 unsigned int rs, re;
2008
2009 for_each_set_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
2010 pcpu_depopulate_chunk(chunk, rs, re);
2011 spin_lock_irq(&pcpu_lock);
2012 pcpu_chunk_depopulated(chunk, rs, re);
2013 spin_unlock_irq(&pcpu_lock);
2014 }
2015 pcpu_destroy_chunk(chunk);
2016 cond_resched();
2017 }
2018 spin_lock_irq(&pcpu_lock);
2019}
2020
2021/**
2022 * pcpu_balance_populated - manage the amount of populated pages
2023 *
2024 * Maintain a certain amount of populated pages to satisfy atomic allocations.
2025 * It is possible that this is called when physical memory is scarce causing
2026 * OOM killer to be triggered. We should avoid doing so until an actual
2027 * allocation causes the failure as it is possible that requests can be
2028 * serviced from already backed regions.
2029 *
2030 * CONTEXT:
2031 * pcpu_lock (can be dropped temporarily)
2032 */
2033static void pcpu_balance_populated(void)
2034{
2035 /* gfp flags passed to underlying allocators */
2036 const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
2037 struct pcpu_chunk *chunk;
2038 int slot, nr_to_pop, ret;
2039
2040 lockdep_assert_held(&pcpu_lock);
2041
2042 /*
2043 * Ensure there are certain number of free populated pages for
2044 * atomic allocs. Fill up from the most packed so that atomic
2045 * allocs don't increase fragmentation. If atomic allocation
2046 * failed previously, always populate the maximum amount. This
2047 * should prevent atomic allocs larger than PAGE_SIZE from keeping
2048 * failing indefinitely; however, large atomic allocs are not
2049 * something we support properly and can be highly unreliable and
2050 * inefficient.
2051 */
2052retry_pop:
2053 if (pcpu_atomic_alloc_failed) {
2054 nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
2055 /* best effort anyway, don't worry about synchronization */
2056 pcpu_atomic_alloc_failed = false;
2057 } else {
2058 nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
2059 pcpu_nr_empty_pop_pages,
2060 0, PCPU_EMPTY_POP_PAGES_HIGH);
2061 }
2062
2063 for (slot = pcpu_size_to_slot(PAGE_SIZE); slot <= pcpu_free_slot; slot++) {
2064 unsigned int nr_unpop = 0, rs, re;
2065
2066 if (!nr_to_pop)
2067 break;
2068
2069 list_for_each_entry(chunk, &pcpu_chunk_lists[slot], list) {
2070 nr_unpop = chunk->nr_pages - chunk->nr_populated;
2071 if (nr_unpop)
2072 break;
2073 }
2074
2075 if (!nr_unpop)
2076 continue;
2077
2078 /* @chunk can't go away while pcpu_alloc_mutex is held */
2079 for_each_clear_bitrange(rs, re, chunk->populated, chunk->nr_pages) {
2080 int nr = min_t(int, re - rs, nr_to_pop);
2081
2082 spin_unlock_irq(&pcpu_lock);
2083 ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
2084 cond_resched();
2085 spin_lock_irq(&pcpu_lock);
2086 if (!ret) {
2087 nr_to_pop -= nr;
2088 pcpu_chunk_populated(chunk, rs, rs + nr);
2089 } else {
2090 nr_to_pop = 0;
2091 }
2092
2093 if (!nr_to_pop)
2094 break;
2095 }
2096 }
2097
2098 if (nr_to_pop) {
2099 /* ran out of chunks to populate, create a new one and retry */
2100 spin_unlock_irq(&pcpu_lock);
2101 chunk = pcpu_create_chunk(gfp);
2102 cond_resched();
2103 spin_lock_irq(&pcpu_lock);
2104 if (chunk) {
2105 pcpu_chunk_relocate(chunk, -1);
2106 goto retry_pop;
2107 }
2108 }
2109}
2110
2111/**
2112 * pcpu_reclaim_populated - scan over to_depopulate chunks and free empty pages
2113 *
2114 * Scan over chunks in the depopulate list and try to release unused populated
2115 * pages back to the system. Depopulated chunks are sidelined to prevent
2116 * repopulating these pages unless required. Fully free chunks are reintegrated
2117 * and freed accordingly (1 is kept around). If we drop below the empty
2118 * populated pages threshold, reintegrate the chunk if it has empty free pages.
2119 * Each chunk is scanned in the reverse order to keep populated pages close to
2120 * the beginning of the chunk.
2121 *
2122 * CONTEXT:
2123 * pcpu_lock (can be dropped temporarily)
2124 *
2125 */
2126static void pcpu_reclaim_populated(void)
2127{
2128 struct pcpu_chunk *chunk;
2129 struct pcpu_block_md *block;
2130 int freed_page_start, freed_page_end;
2131 int i, end;
2132 bool reintegrate;
2133
2134 lockdep_assert_held(&pcpu_lock);
2135
2136 /*
2137 * Once a chunk is isolated to the to_depopulate list, the chunk is no
2138 * longer discoverable to allocations whom may populate pages. The only
2139 * other accessor is the free path which only returns area back to the
2140 * allocator not touching the populated bitmap.
2141 */
2142 while ((chunk = list_first_entry_or_null(
2143 &pcpu_chunk_lists[pcpu_to_depopulate_slot],
2144 struct pcpu_chunk, list))) {
2145 WARN_ON(chunk->immutable);
2146
2147 /*
2148 * Scan chunk's pages in the reverse order to keep populated
2149 * pages close to the beginning of the chunk.
2150 */
2151 freed_page_start = chunk->nr_pages;
2152 freed_page_end = 0;
2153 reintegrate = false;
2154 for (i = chunk->nr_pages - 1, end = -1; i >= 0; i--) {
2155 /* no more work to do */
2156 if (chunk->nr_empty_pop_pages == 0)
2157 break;
2158
2159 /* reintegrate chunk to prevent atomic alloc failures */
2160 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_HIGH) {
2161 reintegrate = true;
2162 break;
2163 }
2164
2165 /*
2166 * If the page is empty and populated, start or
2167 * extend the (i, end) range. If i == 0, decrease
2168 * i and perform the depopulation to cover the last
2169 * (first) page in the chunk.
2170 */
2171 block = chunk->md_blocks + i;
2172 if (block->contig_hint == PCPU_BITMAP_BLOCK_BITS &&
2173 test_bit(i, chunk->populated)) {
2174 if (end == -1)
2175 end = i;
2176 if (i > 0)
2177 continue;
2178 i--;
2179 }
2180
2181 /* depopulate if there is an active range */
2182 if (end == -1)
2183 continue;
2184
2185 spin_unlock_irq(&pcpu_lock);
2186 pcpu_depopulate_chunk(chunk, i + 1, end + 1);
2187 cond_resched();
2188 spin_lock_irq(&pcpu_lock);
2189
2190 pcpu_chunk_depopulated(chunk, i + 1, end + 1);
2191 freed_page_start = min(freed_page_start, i + 1);
2192 freed_page_end = max(freed_page_end, end + 1);
2193
2194 /* reset the range and continue */
2195 end = -1;
2196 }
2197
2198 /* batch tlb flush per chunk to amortize cost */
2199 if (freed_page_start < freed_page_end) {
2200 spin_unlock_irq(&pcpu_lock);
2201 pcpu_post_unmap_tlb_flush(chunk,
2202 freed_page_start,
2203 freed_page_end);
2204 cond_resched();
2205 spin_lock_irq(&pcpu_lock);
2206 }
2207
2208 if (reintegrate || chunk->free_bytes == pcpu_unit_size)
2209 pcpu_reintegrate_chunk(chunk);
2210 else
2211 list_move_tail(&chunk->list,
2212 &pcpu_chunk_lists[pcpu_sidelined_slot]);
2213 }
2214}
2215
2216/**
2217 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
2218 * @work: unused
2219 *
2220 * For each chunk type, manage the number of fully free chunks and the number of
2221 * populated pages. An important thing to consider is when pages are freed and
2222 * how they contribute to the global counts.
2223 */
2224static void pcpu_balance_workfn(struct work_struct *work)
2225{
2226 /*
2227 * pcpu_balance_free() is called twice because the first time we may
2228 * trim pages in the active pcpu_nr_empty_pop_pages which may cause us
2229 * to grow other chunks. This then gives pcpu_reclaim_populated() time
2230 * to move fully free chunks to the active list to be freed if
2231 * appropriate.
2232 */
2233 mutex_lock(&pcpu_alloc_mutex);
2234 spin_lock_irq(&pcpu_lock);
2235
2236 pcpu_balance_free(false);
2237 pcpu_reclaim_populated();
2238 pcpu_balance_populated();
2239 pcpu_balance_free(true);
2240
2241 spin_unlock_irq(&pcpu_lock);
2242 mutex_unlock(&pcpu_alloc_mutex);
2243}
2244
2245/**
2246 * pcpu_alloc_size - the size of the dynamic percpu area
2247 * @ptr: pointer to the dynamic percpu area
2248 *
2249 * Returns the size of the @ptr allocation. This is undefined for statically
2250 * defined percpu variables as there is no corresponding chunk->bound_map.
2251 *
2252 * RETURNS:
2253 * The size of the dynamic percpu area.
2254 *
2255 * CONTEXT:
2256 * Can be called from atomic context.
2257 */
2258size_t pcpu_alloc_size(void __percpu *ptr)
2259{
2260 struct pcpu_chunk *chunk;
2261 unsigned long bit_off, end;
2262 void *addr;
2263
2264 if (!ptr)
2265 return 0;
2266
2267 addr = __pcpu_ptr_to_addr(ptr);
2268 /* No pcpu_lock here: ptr has not been freed, so chunk is still alive */
2269 chunk = pcpu_chunk_addr_search(addr);
2270 bit_off = (addr - chunk->base_addr) / PCPU_MIN_ALLOC_SIZE;
2271 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
2272 bit_off + 1);
2273 return (end - bit_off) * PCPU_MIN_ALLOC_SIZE;
2274}
2275
2276/**
2277 * free_percpu - free percpu area
2278 * @ptr: pointer to area to free
2279 *
2280 * Free percpu area @ptr.
2281 *
2282 * CONTEXT:
2283 * Can be called from atomic context.
2284 */
2285void free_percpu(void __percpu *ptr)
2286{
2287 void *addr;
2288 struct pcpu_chunk *chunk;
2289 unsigned long flags;
2290 int size, off;
2291 bool need_balance = false;
2292
2293 if (!ptr)
2294 return;
2295
2296 kmemleak_free_percpu(ptr);
2297
2298 addr = __pcpu_ptr_to_addr(ptr);
2299 chunk = pcpu_chunk_addr_search(addr);
2300 off = addr - chunk->base_addr;
2301
2302 spin_lock_irqsave(&pcpu_lock, flags);
2303 size = pcpu_free_area(chunk, off);
2304
2305 pcpu_memcg_free_hook(chunk, off, size);
2306
2307 /*
2308 * If there are more than one fully free chunks, wake up grim reaper.
2309 * If the chunk is isolated, it may be in the process of being
2310 * reclaimed. Let reclaim manage cleaning up of that chunk.
2311 */
2312 if (!chunk->isolated && chunk->free_bytes == pcpu_unit_size) {
2313 struct pcpu_chunk *pos;
2314
2315 list_for_each_entry(pos, &pcpu_chunk_lists[pcpu_free_slot], list)
2316 if (pos != chunk) {
2317 need_balance = true;
2318 break;
2319 }
2320 } else if (pcpu_should_reclaim_chunk(chunk)) {
2321 pcpu_isolate_chunk(chunk);
2322 need_balance = true;
2323 }
2324
2325 trace_percpu_free_percpu(chunk->base_addr, off, ptr);
2326
2327 spin_unlock_irqrestore(&pcpu_lock, flags);
2328
2329 if (need_balance)
2330 pcpu_schedule_balance_work();
2331}
2332EXPORT_SYMBOL_GPL(free_percpu);
2333
2334bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
2335{
2336#ifdef CONFIG_SMP
2337 const size_t static_size = __per_cpu_end - __per_cpu_start;
2338 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2339 unsigned int cpu;
2340
2341 for_each_possible_cpu(cpu) {
2342 void *start = per_cpu_ptr(base, cpu);
2343 void *va = (void *)addr;
2344
2345 if (va >= start && va < start + static_size) {
2346 if (can_addr) {
2347 *can_addr = (unsigned long) (va - start);
2348 *can_addr += (unsigned long)
2349 per_cpu_ptr(base, get_boot_cpu_id());
2350 }
2351 return true;
2352 }
2353 }
2354#endif
2355 /* on UP, can't distinguish from other static vars, always false */
2356 return false;
2357}
2358
2359/**
2360 * is_kernel_percpu_address - test whether address is from static percpu area
2361 * @addr: address to test
2362 *
2363 * Test whether @addr belongs to in-kernel static percpu area. Module
2364 * static percpu areas are not considered. For those, use
2365 * is_module_percpu_address().
2366 *
2367 * RETURNS:
2368 * %true if @addr is from in-kernel static percpu area, %false otherwise.
2369 */
2370bool is_kernel_percpu_address(unsigned long addr)
2371{
2372 return __is_kernel_percpu_address(addr, NULL);
2373}
2374
2375/**
2376 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2377 * @addr: the address to be converted to physical address
2378 *
2379 * Given @addr which is dereferenceable address obtained via one of
2380 * percpu access macros, this function translates it into its physical
2381 * address. The caller is responsible for ensuring @addr stays valid
2382 * until this function finishes.
2383 *
2384 * percpu allocator has special setup for the first chunk, which currently
2385 * supports either embedding in linear address space or vmalloc mapping,
2386 * and, from the second one, the backing allocator (currently either vm or
2387 * km) provides translation.
2388 *
2389 * The addr can be translated simply without checking if it falls into the
2390 * first chunk. But the current code reflects better how percpu allocator
2391 * actually works, and the verification can discover both bugs in percpu
2392 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2393 * code.
2394 *
2395 * RETURNS:
2396 * The physical address for @addr.
2397 */
2398phys_addr_t per_cpu_ptr_to_phys(void *addr)
2399{
2400 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2401 bool in_first_chunk = false;
2402 unsigned long first_low, first_high;
2403 unsigned int cpu;
2404
2405 /*
2406 * The following test on unit_low/high isn't strictly
2407 * necessary but will speed up lookups of addresses which
2408 * aren't in the first chunk.
2409 *
2410 * The address check is against full chunk sizes. pcpu_base_addr
2411 * points to the beginning of the first chunk including the
2412 * static region. Assumes good intent as the first chunk may
2413 * not be full (ie. < pcpu_unit_pages in size).
2414 */
2415 first_low = (unsigned long)pcpu_base_addr +
2416 pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2417 first_high = (unsigned long)pcpu_base_addr +
2418 pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2419 if ((unsigned long)addr >= first_low &&
2420 (unsigned long)addr < first_high) {
2421 for_each_possible_cpu(cpu) {
2422 void *start = per_cpu_ptr(base, cpu);
2423
2424 if (addr >= start && addr < start + pcpu_unit_size) {
2425 in_first_chunk = true;
2426 break;
2427 }
2428 }
2429 }
2430
2431 if (in_first_chunk) {
2432 if (!is_vmalloc_addr(addr))
2433 return __pa(addr);
2434 else
2435 return page_to_phys(vmalloc_to_page(addr)) +
2436 offset_in_page(addr);
2437 } else
2438 return page_to_phys(pcpu_addr_to_page(addr)) +
2439 offset_in_page(addr);
2440}
2441
2442/**
2443 * pcpu_alloc_alloc_info - allocate percpu allocation info
2444 * @nr_groups: the number of groups
2445 * @nr_units: the number of units
2446 *
2447 * Allocate ai which is large enough for @nr_groups groups containing
2448 * @nr_units units. The returned ai's groups[0].cpu_map points to the
2449 * cpu_map array which is long enough for @nr_units and filled with
2450 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
2451 * pointer of other groups.
2452 *
2453 * RETURNS:
2454 * Pointer to the allocated pcpu_alloc_info on success, NULL on
2455 * failure.
2456 */
2457struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2458 int nr_units)
2459{
2460 struct pcpu_alloc_info *ai;
2461 size_t base_size, ai_size;
2462 void *ptr;
2463 int unit;
2464
2465 base_size = ALIGN(struct_size(ai, groups, nr_groups),
2466 __alignof__(ai->groups[0].cpu_map[0]));
2467 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2468
2469 ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2470 if (!ptr)
2471 return NULL;
2472 ai = ptr;
2473 ptr += base_size;
2474
2475 ai->groups[0].cpu_map = ptr;
2476
2477 for (unit = 0; unit < nr_units; unit++)
2478 ai->groups[0].cpu_map[unit] = NR_CPUS;
2479
2480 ai->nr_groups = nr_groups;
2481 ai->__ai_size = PFN_ALIGN(ai_size);
2482
2483 return ai;
2484}
2485
2486/**
2487 * pcpu_free_alloc_info - free percpu allocation info
2488 * @ai: pcpu_alloc_info to free
2489 *
2490 * Free @ai which was allocated by pcpu_alloc_alloc_info().
2491 */
2492void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2493{
2494 memblock_free(ai, ai->__ai_size);
2495}
2496
2497/**
2498 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2499 * @lvl: loglevel
2500 * @ai: allocation info to dump
2501 *
2502 * Print out information about @ai using loglevel @lvl.
2503 */
2504static void pcpu_dump_alloc_info(const char *lvl,
2505 const struct pcpu_alloc_info *ai)
2506{
2507 int group_width = 1, cpu_width = 1, width;
2508 char empty_str[] = "--------";
2509 int alloc = 0, alloc_end = 0;
2510 int group, v;
2511 int upa, apl; /* units per alloc, allocs per line */
2512
2513 v = ai->nr_groups;
2514 while (v /= 10)
2515 group_width++;
2516
2517 v = num_possible_cpus();
2518 while (v /= 10)
2519 cpu_width++;
2520 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2521
2522 upa = ai->alloc_size / ai->unit_size;
2523 width = upa * (cpu_width + 1) + group_width + 3;
2524 apl = rounddown_pow_of_two(max(60 / width, 1));
2525
2526 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2527 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2528 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2529
2530 for (group = 0; group < ai->nr_groups; group++) {
2531 const struct pcpu_group_info *gi = &ai->groups[group];
2532 int unit = 0, unit_end = 0;
2533
2534 BUG_ON(gi->nr_units % upa);
2535 for (alloc_end += gi->nr_units / upa;
2536 alloc < alloc_end; alloc++) {
2537 if (!(alloc % apl)) {
2538 pr_cont("\n");
2539 printk("%spcpu-alloc: ", lvl);
2540 }
2541 pr_cont("[%0*d] ", group_width, group);
2542
2543 for (unit_end += upa; unit < unit_end; unit++)
2544 if (gi->cpu_map[unit] != NR_CPUS)
2545 pr_cont("%0*d ",
2546 cpu_width, gi->cpu_map[unit]);
2547 else
2548 pr_cont("%s ", empty_str);
2549 }
2550 }
2551 pr_cont("\n");
2552}
2553
2554/**
2555 * pcpu_setup_first_chunk - initialize the first percpu chunk
2556 * @ai: pcpu_alloc_info describing how to percpu area is shaped
2557 * @base_addr: mapped address
2558 *
2559 * Initialize the first percpu chunk which contains the kernel static
2560 * percpu area. This function is to be called from arch percpu area
2561 * setup path.
2562 *
2563 * @ai contains all information necessary to initialize the first
2564 * chunk and prime the dynamic percpu allocator.
2565 *
2566 * @ai->static_size is the size of static percpu area.
2567 *
2568 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2569 * reserve after the static area in the first chunk. This reserves
2570 * the first chunk such that it's available only through reserved
2571 * percpu allocation. This is primarily used to serve module percpu
2572 * static areas on architectures where the addressing model has
2573 * limited offset range for symbol relocations to guarantee module
2574 * percpu symbols fall inside the relocatable range.
2575 *
2576 * @ai->dyn_size determines the number of bytes available for dynamic
2577 * allocation in the first chunk. The area between @ai->static_size +
2578 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2579 *
2580 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2581 * and equal to or larger than @ai->static_size + @ai->reserved_size +
2582 * @ai->dyn_size.
2583 *
2584 * @ai->atom_size is the allocation atom size and used as alignment
2585 * for vm areas.
2586 *
2587 * @ai->alloc_size is the allocation size and always multiple of
2588 * @ai->atom_size. This is larger than @ai->atom_size if
2589 * @ai->unit_size is larger than @ai->atom_size.
2590 *
2591 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2592 * percpu areas. Units which should be colocated are put into the
2593 * same group. Dynamic VM areas will be allocated according to these
2594 * groupings. If @ai->nr_groups is zero, a single group containing
2595 * all units is assumed.
2596 *
2597 * The caller should have mapped the first chunk at @base_addr and
2598 * copied static data to each unit.
2599 *
2600 * The first chunk will always contain a static and a dynamic region.
2601 * However, the static region is not managed by any chunk. If the first
2602 * chunk also contains a reserved region, it is served by two chunks -
2603 * one for the reserved region and one for the dynamic region. They
2604 * share the same vm, but use offset regions in the area allocation map.
2605 * The chunk serving the dynamic region is circulated in the chunk slots
2606 * and available for dynamic allocation like any other chunk.
2607 */
2608void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2609 void *base_addr)
2610{
2611 size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2612 size_t static_size, dyn_size;
2613 unsigned long *group_offsets;
2614 size_t *group_sizes;
2615 unsigned long *unit_off;
2616 unsigned int cpu;
2617 int *unit_map;
2618 int group, unit, i;
2619 unsigned long tmp_addr;
2620 size_t alloc_size;
2621
2622#define PCPU_SETUP_BUG_ON(cond) do { \
2623 if (unlikely(cond)) { \
2624 pr_emerg("failed to initialize, %s\n", #cond); \
2625 pr_emerg("cpu_possible_mask=%*pb\n", \
2626 cpumask_pr_args(cpu_possible_mask)); \
2627 pcpu_dump_alloc_info(KERN_EMERG, ai); \
2628 BUG(); \
2629 } \
2630} while (0)
2631
2632 /* sanity checks */
2633 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2634#ifdef CONFIG_SMP
2635 PCPU_SETUP_BUG_ON(!ai->static_size);
2636 PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2637#endif
2638 PCPU_SETUP_BUG_ON(!base_addr);
2639 PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2640 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2641 PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2642 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2643 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2644 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2645 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2646 PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2647 IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2648 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2649
2650 /* process group information and build config tables accordingly */
2651 alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2652 group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2653 if (!group_offsets)
2654 panic("%s: Failed to allocate %zu bytes\n", __func__,
2655 alloc_size);
2656
2657 alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2658 group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2659 if (!group_sizes)
2660 panic("%s: Failed to allocate %zu bytes\n", __func__,
2661 alloc_size);
2662
2663 alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2664 unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2665 if (!unit_map)
2666 panic("%s: Failed to allocate %zu bytes\n", __func__,
2667 alloc_size);
2668
2669 alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2670 unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2671 if (!unit_off)
2672 panic("%s: Failed to allocate %zu bytes\n", __func__,
2673 alloc_size);
2674
2675 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2676 unit_map[cpu] = UINT_MAX;
2677
2678 pcpu_low_unit_cpu = NR_CPUS;
2679 pcpu_high_unit_cpu = NR_CPUS;
2680
2681 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2682 const struct pcpu_group_info *gi = &ai->groups[group];
2683
2684 group_offsets[group] = gi->base_offset;
2685 group_sizes[group] = gi->nr_units * ai->unit_size;
2686
2687 for (i = 0; i < gi->nr_units; i++) {
2688 cpu = gi->cpu_map[i];
2689 if (cpu == NR_CPUS)
2690 continue;
2691
2692 PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2693 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2694 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2695
2696 unit_map[cpu] = unit + i;
2697 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2698
2699 /* determine low/high unit_cpu */
2700 if (pcpu_low_unit_cpu == NR_CPUS ||
2701 unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2702 pcpu_low_unit_cpu = cpu;
2703 if (pcpu_high_unit_cpu == NR_CPUS ||
2704 unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2705 pcpu_high_unit_cpu = cpu;
2706 }
2707 }
2708 pcpu_nr_units = unit;
2709
2710 for_each_possible_cpu(cpu)
2711 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2712
2713 /* we're done parsing the input, undefine BUG macro and dump config */
2714#undef PCPU_SETUP_BUG_ON
2715 pcpu_dump_alloc_info(KERN_DEBUG, ai);
2716
2717 pcpu_nr_groups = ai->nr_groups;
2718 pcpu_group_offsets = group_offsets;
2719 pcpu_group_sizes = group_sizes;
2720 pcpu_unit_map = unit_map;
2721 pcpu_unit_offsets = unit_off;
2722
2723 /* determine basic parameters */
2724 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2725 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2726 pcpu_atom_size = ai->atom_size;
2727 pcpu_chunk_struct_size = struct_size((struct pcpu_chunk *)0, populated,
2728 BITS_TO_LONGS(pcpu_unit_pages));
2729
2730 pcpu_stats_save_ai(ai);
2731
2732 /*
2733 * Allocate chunk slots. The slots after the active slots are:
2734 * sidelined_slot - isolated, depopulated chunks
2735 * free_slot - fully free chunks
2736 * to_depopulate_slot - isolated, chunks to depopulate
2737 */
2738 pcpu_sidelined_slot = __pcpu_size_to_slot(pcpu_unit_size) + 1;
2739 pcpu_free_slot = pcpu_sidelined_slot + 1;
2740 pcpu_to_depopulate_slot = pcpu_free_slot + 1;
2741 pcpu_nr_slots = pcpu_to_depopulate_slot + 1;
2742 pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
2743 sizeof(pcpu_chunk_lists[0]),
2744 SMP_CACHE_BYTES);
2745 if (!pcpu_chunk_lists)
2746 panic("%s: Failed to allocate %zu bytes\n", __func__,
2747 pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]));
2748
2749 for (i = 0; i < pcpu_nr_slots; i++)
2750 INIT_LIST_HEAD(&pcpu_chunk_lists[i]);
2751
2752 /*
2753 * The end of the static region needs to be aligned with the
2754 * minimum allocation size as this offsets the reserved and
2755 * dynamic region. The first chunk ends page aligned by
2756 * expanding the dynamic region, therefore the dynamic region
2757 * can be shrunk to compensate while still staying above the
2758 * configured sizes.
2759 */
2760 static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2761 dyn_size = ai->dyn_size - (static_size - ai->static_size);
2762
2763 /*
2764 * Initialize first chunk:
2765 * This chunk is broken up into 3 parts:
2766 * < static | [reserved] | dynamic >
2767 * - static - there is no backing chunk because these allocations can
2768 * never be freed.
2769 * - reserved (pcpu_reserved_chunk) - exists primarily to serve
2770 * allocations from module load.
2771 * - dynamic (pcpu_first_chunk) - serves the dynamic part of the first
2772 * chunk.
2773 */
2774 tmp_addr = (unsigned long)base_addr + static_size;
2775 if (ai->reserved_size)
2776 pcpu_reserved_chunk = pcpu_alloc_first_chunk(tmp_addr,
2777 ai->reserved_size);
2778 tmp_addr = (unsigned long)base_addr + static_size + ai->reserved_size;
2779 pcpu_first_chunk = pcpu_alloc_first_chunk(tmp_addr, dyn_size);
2780
2781 pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2782 pcpu_chunk_relocate(pcpu_first_chunk, -1);
2783
2784 /* include all regions of the first chunk */
2785 pcpu_nr_populated += PFN_DOWN(size_sum);
2786
2787 pcpu_stats_chunk_alloc();
2788 trace_percpu_create_chunk(base_addr);
2789
2790 /* we're done */
2791 pcpu_base_addr = base_addr;
2792}
2793
2794#ifdef CONFIG_SMP
2795
2796const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2797 [PCPU_FC_AUTO] = "auto",
2798 [PCPU_FC_EMBED] = "embed",
2799 [PCPU_FC_PAGE] = "page",
2800};
2801
2802enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2803
2804static int __init percpu_alloc_setup(char *str)
2805{
2806 if (!str)
2807 return -EINVAL;
2808
2809 if (0)
2810 /* nada */;
2811#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2812 else if (!strcmp(str, "embed"))
2813 pcpu_chosen_fc = PCPU_FC_EMBED;
2814#endif
2815#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2816 else if (!strcmp(str, "page"))
2817 pcpu_chosen_fc = PCPU_FC_PAGE;
2818#endif
2819 else
2820 pr_warn("unknown allocator %s specified\n", str);
2821
2822 return 0;
2823}
2824early_param("percpu_alloc", percpu_alloc_setup);
2825
2826/*
2827 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2828 * Build it if needed by the arch config or the generic setup is going
2829 * to be used.
2830 */
2831#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2832 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2833#define BUILD_EMBED_FIRST_CHUNK
2834#endif
2835
2836/* build pcpu_page_first_chunk() iff needed by the arch config */
2837#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2838#define BUILD_PAGE_FIRST_CHUNK
2839#endif
2840
2841/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2842#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2843/**
2844 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2845 * @reserved_size: the size of reserved percpu area in bytes
2846 * @dyn_size: minimum free size for dynamic allocation in bytes
2847 * @atom_size: allocation atom size
2848 * @cpu_distance_fn: callback to determine distance between cpus, optional
2849 *
2850 * This function determines grouping of units, their mappings to cpus
2851 * and other parameters considering needed percpu size, allocation
2852 * atom size and distances between CPUs.
2853 *
2854 * Groups are always multiples of atom size and CPUs which are of
2855 * LOCAL_DISTANCE both ways are grouped together and share space for
2856 * units in the same group. The returned configuration is guaranteed
2857 * to have CPUs on different nodes on different groups and >=75% usage
2858 * of allocated virtual address space.
2859 *
2860 * RETURNS:
2861 * On success, pointer to the new allocation_info is returned. On
2862 * failure, ERR_PTR value is returned.
2863 */
2864static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
2865 size_t reserved_size, size_t dyn_size,
2866 size_t atom_size,
2867 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2868{
2869 static int group_map[NR_CPUS] __initdata;
2870 static int group_cnt[NR_CPUS] __initdata;
2871 static struct cpumask mask __initdata;
2872 const size_t static_size = __per_cpu_end - __per_cpu_start;
2873 int nr_groups = 1, nr_units = 0;
2874 size_t size_sum, min_unit_size, alloc_size;
2875 int upa, max_upa, best_upa; /* units_per_alloc */
2876 int last_allocs, group, unit;
2877 unsigned int cpu, tcpu;
2878 struct pcpu_alloc_info *ai;
2879 unsigned int *cpu_map;
2880
2881 /* this function may be called multiple times */
2882 memset(group_map, 0, sizeof(group_map));
2883 memset(group_cnt, 0, sizeof(group_cnt));
2884 cpumask_clear(&mask);
2885
2886 /* calculate size_sum and ensure dyn_size is enough for early alloc */
2887 size_sum = PFN_ALIGN(static_size + reserved_size +
2888 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2889 dyn_size = size_sum - static_size - reserved_size;
2890
2891 /*
2892 * Determine min_unit_size, alloc_size and max_upa such that
2893 * alloc_size is multiple of atom_size and is the smallest
2894 * which can accommodate 4k aligned segments which are equal to
2895 * or larger than min_unit_size.
2896 */
2897 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2898
2899 /* determine the maximum # of units that can fit in an allocation */
2900 alloc_size = roundup(min_unit_size, atom_size);
2901 upa = alloc_size / min_unit_size;
2902 while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2903 upa--;
2904 max_upa = upa;
2905
2906 cpumask_copy(&mask, cpu_possible_mask);
2907
2908 /* group cpus according to their proximity */
2909 for (group = 0; !cpumask_empty(&mask); group++) {
2910 /* pop the group's first cpu */
2911 cpu = cpumask_first(&mask);
2912 group_map[cpu] = group;
2913 group_cnt[group]++;
2914 cpumask_clear_cpu(cpu, &mask);
2915
2916 for_each_cpu(tcpu, &mask) {
2917 if (!cpu_distance_fn ||
2918 (cpu_distance_fn(cpu, tcpu) == LOCAL_DISTANCE &&
2919 cpu_distance_fn(tcpu, cpu) == LOCAL_DISTANCE)) {
2920 group_map[tcpu] = group;
2921 group_cnt[group]++;
2922 cpumask_clear_cpu(tcpu, &mask);
2923 }
2924 }
2925 }
2926 nr_groups = group;
2927
2928 /*
2929 * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2930 * Expand the unit_size until we use >= 75% of the units allocated.
2931 * Related to atom_size, which could be much larger than the unit_size.
2932 */
2933 last_allocs = INT_MAX;
2934 best_upa = 0;
2935 for (upa = max_upa; upa; upa--) {
2936 int allocs = 0, wasted = 0;
2937
2938 if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2939 continue;
2940
2941 for (group = 0; group < nr_groups; group++) {
2942 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2943 allocs += this_allocs;
2944 wasted += this_allocs * upa - group_cnt[group];
2945 }
2946
2947 /*
2948 * Don't accept if wastage is over 1/3. The
2949 * greater-than comparison ensures upa==1 always
2950 * passes the following check.
2951 */
2952 if (wasted > num_possible_cpus() / 3)
2953 continue;
2954
2955 /* and then don't consume more memory */
2956 if (allocs > last_allocs)
2957 break;
2958 last_allocs = allocs;
2959 best_upa = upa;
2960 }
2961 BUG_ON(!best_upa);
2962 upa = best_upa;
2963
2964 /* allocate and fill alloc_info */
2965 for (group = 0; group < nr_groups; group++)
2966 nr_units += roundup(group_cnt[group], upa);
2967
2968 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2969 if (!ai)
2970 return ERR_PTR(-ENOMEM);
2971 cpu_map = ai->groups[0].cpu_map;
2972
2973 for (group = 0; group < nr_groups; group++) {
2974 ai->groups[group].cpu_map = cpu_map;
2975 cpu_map += roundup(group_cnt[group], upa);
2976 }
2977
2978 ai->static_size = static_size;
2979 ai->reserved_size = reserved_size;
2980 ai->dyn_size = dyn_size;
2981 ai->unit_size = alloc_size / upa;
2982 ai->atom_size = atom_size;
2983 ai->alloc_size = alloc_size;
2984
2985 for (group = 0, unit = 0; group < nr_groups; group++) {
2986 struct pcpu_group_info *gi = &ai->groups[group];
2987
2988 /*
2989 * Initialize base_offset as if all groups are located
2990 * back-to-back. The caller should update this to
2991 * reflect actual allocation.
2992 */
2993 gi->base_offset = unit * ai->unit_size;
2994
2995 for_each_possible_cpu(cpu)
2996 if (group_map[cpu] == group)
2997 gi->cpu_map[gi->nr_units++] = cpu;
2998 gi->nr_units = roundup(gi->nr_units, upa);
2999 unit += gi->nr_units;
3000 }
3001 BUG_ON(unit != nr_units);
3002
3003 return ai;
3004}
3005
3006static void * __init pcpu_fc_alloc(unsigned int cpu, size_t size, size_t align,
3007 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
3008{
3009 const unsigned long goal = __pa(MAX_DMA_ADDRESS);
3010#ifdef CONFIG_NUMA
3011 int node = NUMA_NO_NODE;
3012 void *ptr;
3013
3014 if (cpu_to_nd_fn)
3015 node = cpu_to_nd_fn(cpu);
3016
3017 if (node == NUMA_NO_NODE || !node_online(node) || !NODE_DATA(node)) {
3018 ptr = memblock_alloc_from(size, align, goal);
3019 pr_info("cpu %d has no node %d or node-local memory\n",
3020 cpu, node);
3021 pr_debug("per cpu data for cpu%d %zu bytes at 0x%llx\n",
3022 cpu, size, (u64)__pa(ptr));
3023 } else {
3024 ptr = memblock_alloc_try_nid(size, align, goal,
3025 MEMBLOCK_ALLOC_ACCESSIBLE,
3026 node);
3027
3028 pr_debug("per cpu data for cpu%d %zu bytes on node%d at 0x%llx\n",
3029 cpu, size, node, (u64)__pa(ptr));
3030 }
3031 return ptr;
3032#else
3033 return memblock_alloc_from(size, align, goal);
3034#endif
3035}
3036
3037static void __init pcpu_fc_free(void *ptr, size_t size)
3038{
3039 memblock_free(ptr, size);
3040}
3041#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
3042
3043#if defined(BUILD_EMBED_FIRST_CHUNK)
3044/**
3045 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
3046 * @reserved_size: the size of reserved percpu area in bytes
3047 * @dyn_size: minimum free size for dynamic allocation in bytes
3048 * @atom_size: allocation atom size
3049 * @cpu_distance_fn: callback to determine distance between cpus, optional
3050 * @cpu_to_nd_fn: callback to convert cpu to it's node, optional
3051 *
3052 * This is a helper to ease setting up embedded first percpu chunk and
3053 * can be called where pcpu_setup_first_chunk() is expected.
3054 *
3055 * If this function is used to setup the first chunk, it is allocated
3056 * by calling pcpu_fc_alloc and used as-is without being mapped into
3057 * vmalloc area. Allocations are always whole multiples of @atom_size
3058 * aligned to @atom_size.
3059 *
3060 * This enables the first chunk to piggy back on the linear physical
3061 * mapping which often uses larger page size. Please note that this
3062 * can result in very sparse cpu->unit mapping on NUMA machines thus
3063 * requiring large vmalloc address space. Don't use this allocator if
3064 * vmalloc space is not orders of magnitude larger than distances
3065 * between node memory addresses (ie. 32bit NUMA machines).
3066 *
3067 * @dyn_size specifies the minimum dynamic area size.
3068 *
3069 * If the needed size is smaller than the minimum or specified unit
3070 * size, the leftover is returned using pcpu_fc_free.
3071 *
3072 * RETURNS:
3073 * 0 on success, -errno on failure.
3074 */
3075int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
3076 size_t atom_size,
3077 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
3078 pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
3079{
3080 void *base = (void *)ULONG_MAX;
3081 void **areas = NULL;
3082 struct pcpu_alloc_info *ai;
3083 size_t size_sum, areas_size;
3084 unsigned long max_distance;
3085 int group, i, highest_group, rc = 0;
3086
3087 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
3088 cpu_distance_fn);
3089 if (IS_ERR(ai))
3090 return PTR_ERR(ai);
3091
3092 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
3093 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
3094
3095 areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
3096 if (!areas) {
3097 rc = -ENOMEM;
3098 goto out_free;
3099 }
3100
3101 /* allocate, copy and determine base address & max_distance */
3102 highest_group = 0;
3103 for (group = 0; group < ai->nr_groups; group++) {
3104 struct pcpu_group_info *gi = &ai->groups[group];
3105 unsigned int cpu = NR_CPUS;
3106 void *ptr;
3107
3108 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
3109 cpu = gi->cpu_map[i];
3110 BUG_ON(cpu == NR_CPUS);
3111
3112 /* allocate space for the whole group */
3113 ptr = pcpu_fc_alloc(cpu, gi->nr_units * ai->unit_size, atom_size, cpu_to_nd_fn);
3114 if (!ptr) {
3115 rc = -ENOMEM;
3116 goto out_free_areas;
3117 }
3118 /* kmemleak tracks the percpu allocations separately */
3119 kmemleak_ignore_phys(__pa(ptr));
3120 areas[group] = ptr;
3121
3122 base = min(ptr, base);
3123 if (ptr > areas[highest_group])
3124 highest_group = group;
3125 }
3126 max_distance = areas[highest_group] - base;
3127 max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
3128
3129 /* warn if maximum distance is further than 75% of vmalloc space */
3130 if (max_distance > VMALLOC_TOTAL * 3 / 4) {
3131 pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
3132 max_distance, VMALLOC_TOTAL);
3133#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
3134 /* and fail if we have fallback */
3135 rc = -EINVAL;
3136 goto out_free_areas;
3137#endif
3138 }
3139
3140 /*
3141 * Copy data and free unused parts. This should happen after all
3142 * allocations are complete; otherwise, we may end up with
3143 * overlapping groups.
3144 */
3145 for (group = 0; group < ai->nr_groups; group++) {
3146 struct pcpu_group_info *gi = &ai->groups[group];
3147 void *ptr = areas[group];
3148
3149 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
3150 if (gi->cpu_map[i] == NR_CPUS) {
3151 /* unused unit, free whole */
3152 pcpu_fc_free(ptr, ai->unit_size);
3153 continue;
3154 }
3155 /* copy and return the unused part */
3156 memcpy(ptr, __per_cpu_load, ai->static_size);
3157 pcpu_fc_free(ptr + size_sum, ai->unit_size - size_sum);
3158 }
3159 }
3160
3161 /* base address is now known, determine group base offsets */
3162 for (group = 0; group < ai->nr_groups; group++) {
3163 ai->groups[group].base_offset = areas[group] - base;
3164 }
3165
3166 pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
3167 PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
3168 ai->dyn_size, ai->unit_size);
3169
3170 pcpu_setup_first_chunk(ai, base);
3171 goto out_free;
3172
3173out_free_areas:
3174 for (group = 0; group < ai->nr_groups; group++)
3175 if (areas[group])
3176 pcpu_fc_free(areas[group],
3177 ai->groups[group].nr_units * ai->unit_size);
3178out_free:
3179 pcpu_free_alloc_info(ai);
3180 if (areas)
3181 memblock_free(areas, areas_size);
3182 return rc;
3183}
3184#endif /* BUILD_EMBED_FIRST_CHUNK */
3185
3186#ifdef BUILD_PAGE_FIRST_CHUNK
3187#include <asm/pgalloc.h>
3188
3189#ifndef P4D_TABLE_SIZE
3190#define P4D_TABLE_SIZE PAGE_SIZE
3191#endif
3192
3193#ifndef PUD_TABLE_SIZE
3194#define PUD_TABLE_SIZE PAGE_SIZE
3195#endif
3196
3197#ifndef PMD_TABLE_SIZE
3198#define PMD_TABLE_SIZE PAGE_SIZE
3199#endif
3200
3201#ifndef PTE_TABLE_SIZE
3202#define PTE_TABLE_SIZE PAGE_SIZE
3203#endif
3204void __init __weak pcpu_populate_pte(unsigned long addr)
3205{
3206 pgd_t *pgd = pgd_offset_k(addr);
3207 p4d_t *p4d;
3208 pud_t *pud;
3209 pmd_t *pmd;
3210
3211 if (pgd_none(*pgd)) {
3212 p4d = memblock_alloc(P4D_TABLE_SIZE, P4D_TABLE_SIZE);
3213 if (!p4d)
3214 goto err_alloc;
3215 pgd_populate(&init_mm, pgd, p4d);
3216 }
3217
3218 p4d = p4d_offset(pgd, addr);
3219 if (p4d_none(*p4d)) {
3220 pud = memblock_alloc(PUD_TABLE_SIZE, PUD_TABLE_SIZE);
3221 if (!pud)
3222 goto err_alloc;
3223 p4d_populate(&init_mm, p4d, pud);
3224 }
3225
3226 pud = pud_offset(p4d, addr);
3227 if (pud_none(*pud)) {
3228 pmd = memblock_alloc(PMD_TABLE_SIZE, PMD_TABLE_SIZE);
3229 if (!pmd)
3230 goto err_alloc;
3231 pud_populate(&init_mm, pud, pmd);
3232 }
3233
3234 pmd = pmd_offset(pud, addr);
3235 if (!pmd_present(*pmd)) {
3236 pte_t *new;
3237
3238 new = memblock_alloc(PTE_TABLE_SIZE, PTE_TABLE_SIZE);
3239 if (!new)
3240 goto err_alloc;
3241 pmd_populate_kernel(&init_mm, pmd, new);
3242 }
3243
3244 return;
3245
3246err_alloc:
3247 panic("%s: Failed to allocate memory\n", __func__);
3248}
3249
3250/**
3251 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
3252 * @reserved_size: the size of reserved percpu area in bytes
3253 * @cpu_to_nd_fn: callback to convert cpu to it's node, optional
3254 *
3255 * This is a helper to ease setting up page-remapped first percpu
3256 * chunk and can be called where pcpu_setup_first_chunk() is expected.
3257 *
3258 * This is the basic allocator. Static percpu area is allocated
3259 * page-by-page into vmalloc area.
3260 *
3261 * RETURNS:
3262 * 0 on success, -errno on failure.
3263 */
3264int __init pcpu_page_first_chunk(size_t reserved_size, pcpu_fc_cpu_to_node_fn_t cpu_to_nd_fn)
3265{
3266 static struct vm_struct vm;
3267 struct pcpu_alloc_info *ai;
3268 char psize_str[16];
3269 int unit_pages;
3270 size_t pages_size;
3271 struct page **pages;
3272 int unit, i, j, rc = 0;
3273 int upa;
3274 int nr_g0_units;
3275
3276 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
3277
3278 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
3279 if (IS_ERR(ai))
3280 return PTR_ERR(ai);
3281 BUG_ON(ai->nr_groups != 1);
3282 upa = ai->alloc_size/ai->unit_size;
3283 nr_g0_units = roundup(num_possible_cpus(), upa);
3284 if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
3285 pcpu_free_alloc_info(ai);
3286 return -EINVAL;
3287 }
3288
3289 unit_pages = ai->unit_size >> PAGE_SHIFT;
3290
3291 /* unaligned allocations can't be freed, round up to page size */
3292 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
3293 sizeof(pages[0]));
3294 pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
3295 if (!pages)
3296 panic("%s: Failed to allocate %zu bytes\n", __func__,
3297 pages_size);
3298
3299 /* allocate pages */
3300 j = 0;
3301 for (unit = 0; unit < num_possible_cpus(); unit++) {
3302 unsigned int cpu = ai->groups[0].cpu_map[unit];
3303 for (i = 0; i < unit_pages; i++) {
3304 void *ptr;
3305
3306 ptr = pcpu_fc_alloc(cpu, PAGE_SIZE, PAGE_SIZE, cpu_to_nd_fn);
3307 if (!ptr) {
3308 pr_warn("failed to allocate %s page for cpu%u\n",
3309 psize_str, cpu);
3310 goto enomem;
3311 }
3312 /* kmemleak tracks the percpu allocations separately */
3313 kmemleak_ignore_phys(__pa(ptr));
3314 pages[j++] = virt_to_page(ptr);
3315 }
3316 }
3317
3318 /* allocate vm area, map the pages and copy static data */
3319 vm.flags = VM_ALLOC;
3320 vm.size = num_possible_cpus() * ai->unit_size;
3321 vm_area_register_early(&vm, PAGE_SIZE);
3322
3323 for (unit = 0; unit < num_possible_cpus(); unit++) {
3324 unsigned long unit_addr =
3325 (unsigned long)vm.addr + unit * ai->unit_size;
3326
3327 for (i = 0; i < unit_pages; i++)
3328 pcpu_populate_pte(unit_addr + (i << PAGE_SHIFT));
3329
3330 /* pte already populated, the following shouldn't fail */
3331 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
3332 unit_pages);
3333 if (rc < 0)
3334 panic("failed to map percpu area, err=%d\n", rc);
3335
3336 flush_cache_vmap_early(unit_addr, unit_addr + ai->unit_size);
3337
3338 /* copy static data */
3339 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
3340 }
3341
3342 /* we're ready, commit */
3343 pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
3344 unit_pages, psize_str, ai->static_size,
3345 ai->reserved_size, ai->dyn_size);
3346
3347 pcpu_setup_first_chunk(ai, vm.addr);
3348 goto out_free_ar;
3349
3350enomem:
3351 while (--j >= 0)
3352 pcpu_fc_free(page_address(pages[j]), PAGE_SIZE);
3353 rc = -ENOMEM;
3354out_free_ar:
3355 memblock_free(pages, pages_size);
3356 pcpu_free_alloc_info(ai);
3357 return rc;
3358}
3359#endif /* BUILD_PAGE_FIRST_CHUNK */
3360
3361#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
3362/*
3363 * Generic SMP percpu area setup.
3364 *
3365 * The embedding helper is used because its behavior closely resembles
3366 * the original non-dynamic generic percpu area setup. This is
3367 * important because many archs have addressing restrictions and might
3368 * fail if the percpu area is located far away from the previous
3369 * location. As an added bonus, in non-NUMA cases, embedding is
3370 * generally a good idea TLB-wise because percpu area can piggy back
3371 * on the physical linear memory mapping which uses large page
3372 * mappings on applicable archs.
3373 */
3374unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
3375EXPORT_SYMBOL(__per_cpu_offset);
3376
3377void __init setup_per_cpu_areas(void)
3378{
3379 unsigned long delta;
3380 unsigned int cpu;
3381 int rc;
3382
3383 /*
3384 * Always reserve area for module percpu variables. That's
3385 * what the legacy allocator did.
3386 */
3387 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE, PERCPU_DYNAMIC_RESERVE,
3388 PAGE_SIZE, NULL, NULL);
3389 if (rc < 0)
3390 panic("Failed to initialize percpu areas.");
3391
3392 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
3393 for_each_possible_cpu(cpu)
3394 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
3395}
3396#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
3397
3398#else /* CONFIG_SMP */
3399
3400/*
3401 * UP percpu area setup.
3402 *
3403 * UP always uses km-based percpu allocator with identity mapping.
3404 * Static percpu variables are indistinguishable from the usual static
3405 * variables and don't require any special preparation.
3406 */
3407void __init setup_per_cpu_areas(void)
3408{
3409 const size_t unit_size =
3410 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
3411 PERCPU_DYNAMIC_RESERVE));
3412 struct pcpu_alloc_info *ai;
3413 void *fc;
3414
3415 ai = pcpu_alloc_alloc_info(1, 1);
3416 fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3417 if (!ai || !fc)
3418 panic("Failed to allocate memory for percpu areas.");
3419 /* kmemleak tracks the percpu allocations separately */
3420 kmemleak_ignore_phys(__pa(fc));
3421
3422 ai->dyn_size = unit_size;
3423 ai->unit_size = unit_size;
3424 ai->atom_size = unit_size;
3425 ai->alloc_size = unit_size;
3426 ai->groups[0].nr_units = 1;
3427 ai->groups[0].cpu_map[0] = 0;
3428
3429 pcpu_setup_first_chunk(ai, fc);
3430 pcpu_free_alloc_info(ai);
3431}
3432
3433#endif /* CONFIG_SMP */
3434
3435/*
3436 * pcpu_nr_pages - calculate total number of populated backing pages
3437 *
3438 * This reflects the number of pages populated to back chunks. Metadata is
3439 * excluded in the number exposed in meminfo as the number of backing pages
3440 * scales with the number of cpus and can quickly outweigh the memory used for
3441 * metadata. It also keeps this calculation nice and simple.
3442 *
3443 * RETURNS:
3444 * Total number of populated backing pages in use by the allocator.
3445 */
3446unsigned long pcpu_nr_pages(void)
3447{
3448 return pcpu_nr_populated * pcpu_nr_units;
3449}
3450
3451/*
3452 * Percpu allocator is initialized early during boot when neither slab or
3453 * workqueue is available. Plug async management until everything is up
3454 * and running.
3455 */
3456static int __init percpu_enable_async(void)
3457{
3458 pcpu_async_enabled = true;
3459 return 0;
3460}
3461subsys_initcall(percpu_enable_async);