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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/*
2 * mm/percpu.c - percpu memory allocator
3 *
4 * Copyright (C) 2009 SUSE Linux Products GmbH
5 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
6 *
7 * Copyright (C) 2017 Facebook Inc.
8 * Copyright (C) 2017 Dennis Zhou <dennisszhou@gmail.com>
9 *
10 * This file is released under the GPLv2 license.
11 *
12 * The percpu allocator handles both static and dynamic areas. Percpu
13 * areas are allocated in chunks which are divided into units. There is
14 * a 1-to-1 mapping for units to possible cpus. These units are grouped
15 * based on NUMA properties of the machine.
16 *
17 * c0 c1 c2
18 * ------------------- ------------------- ------------
19 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
20 * ------------------- ...... ------------------- .... ------------
21 *
22 * Allocation is done by offsets into a unit's address space. Ie., an
23 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
24 * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
25 * and even sparse. Access is handled by configuring percpu base
26 * registers according to the cpu to unit mappings and offsetting the
27 * base address using pcpu_unit_size.
28 *
29 * There is special consideration for the first chunk which must handle
30 * the static percpu variables in the kernel image as allocation services
31 * are not online yet. In short, the first chunk is structured like so:
32 *
33 * <Static | [Reserved] | Dynamic>
34 *
35 * The static data is copied from the original section managed by the
36 * linker. The reserved section, if non-zero, primarily manages static
37 * percpu variables from kernel modules. Finally, the dynamic section
38 * takes care of normal allocations.
39 *
40 * The allocator organizes chunks into lists according to free size and
41 * tries to allocate from the fullest chunk first. Each chunk is managed
42 * by a bitmap with metadata blocks. The allocation map is updated on
43 * every allocation and free to reflect the current state while the boundary
44 * map is only updated on allocation. Each metadata block contains
45 * information to help mitigate the need to iterate over large portions
46 * of the bitmap. The reverse mapping from page to chunk is stored in
47 * the page's index. Lastly, units are lazily backed and grow in unison.
48 *
49 * There is a unique conversion that goes on here between bytes and bits.
50 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
51 * tracks the number of pages it is responsible for in nr_pages. Helper
52 * functions are used to convert from between the bytes, bits, and blocks.
53 * All hints are managed in bits unless explicitly stated.
54 *
55 * To use this allocator, arch code should do the following:
56 *
57 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
58 * regular address to percpu pointer and back if they need to be
59 * different from the default
60 *
61 * - use pcpu_setup_first_chunk() during percpu area initialization to
62 * setup the first chunk containing the kernel static percpu area
63 */
64
65#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66
67#include <linux/bitmap.h>
68#include <linux/bootmem.h>
69#include <linux/err.h>
70#include <linux/lcm.h>
71#include <linux/list.h>
72#include <linux/log2.h>
73#include <linux/mm.h>
74#include <linux/module.h>
75#include <linux/mutex.h>
76#include <linux/percpu.h>
77#include <linux/pfn.h>
78#include <linux/slab.h>
79#include <linux/spinlock.h>
80#include <linux/vmalloc.h>
81#include <linux/workqueue.h>
82#include <linux/kmemleak.h>
83#include <linux/sched.h>
84
85#include <asm/cacheflush.h>
86#include <asm/sections.h>
87#include <asm/tlbflush.h>
88#include <asm/io.h>
89
90#define CREATE_TRACE_POINTS
91#include <trace/events/percpu.h>
92
93#include "percpu-internal.h"
94
95/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */
96#define PCPU_SLOT_BASE_SHIFT 5
97
98#define PCPU_EMPTY_POP_PAGES_LOW 2
99#define PCPU_EMPTY_POP_PAGES_HIGH 4
100
101#ifdef CONFIG_SMP
102/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
103#ifndef __addr_to_pcpu_ptr
104#define __addr_to_pcpu_ptr(addr) \
105 (void __percpu *)((unsigned long)(addr) - \
106 (unsigned long)pcpu_base_addr + \
107 (unsigned long)__per_cpu_start)
108#endif
109#ifndef __pcpu_ptr_to_addr
110#define __pcpu_ptr_to_addr(ptr) \
111 (void __force *)((unsigned long)(ptr) + \
112 (unsigned long)pcpu_base_addr - \
113 (unsigned long)__per_cpu_start)
114#endif
115#else /* CONFIG_SMP */
116/* on UP, it's always identity mapped */
117#define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
118#define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
119#endif /* CONFIG_SMP */
120
121static int pcpu_unit_pages __ro_after_init;
122static int pcpu_unit_size __ro_after_init;
123static int pcpu_nr_units __ro_after_init;
124static int pcpu_atom_size __ro_after_init;
125int pcpu_nr_slots __ro_after_init;
126static size_t pcpu_chunk_struct_size __ro_after_init;
127
128/* cpus with the lowest and highest unit addresses */
129static unsigned int pcpu_low_unit_cpu __ro_after_init;
130static unsigned int pcpu_high_unit_cpu __ro_after_init;
131
132/* the address of the first chunk which starts with the kernel static area */
133void *pcpu_base_addr __ro_after_init;
134EXPORT_SYMBOL_GPL(pcpu_base_addr);
135
136static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
137const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
138
139/* group information, used for vm allocation */
140static int pcpu_nr_groups __ro_after_init;
141static const unsigned long *pcpu_group_offsets __ro_after_init;
142static const size_t *pcpu_group_sizes __ro_after_init;
143
144/*
145 * The first chunk which always exists. Note that unlike other
146 * chunks, this one can be allocated and mapped in several different
147 * ways and thus often doesn't live in the vmalloc area.
148 */
149struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
150
151/*
152 * Optional reserved chunk. This chunk reserves part of the first
153 * chunk and serves it for reserved allocations. When the reserved
154 * region doesn't exist, the following variable is NULL.
155 */
156struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
157
158DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
159static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
160
161struct list_head *pcpu_slot __ro_after_init; /* chunk list slots */
162
163/* chunks which need their map areas extended, protected by pcpu_lock */
164static LIST_HEAD(pcpu_map_extend_chunks);
165
166/*
167 * The number of empty populated pages, protected by pcpu_lock. The
168 * reserved chunk doesn't contribute to the count.
169 */
170int pcpu_nr_empty_pop_pages;
171
172/*
173 * Balance work is used to populate or destroy chunks asynchronously. We
174 * try to keep the number of populated free pages between
175 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
176 * empty chunk.
177 */
178static void pcpu_balance_workfn(struct work_struct *work);
179static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
180static bool pcpu_async_enabled __read_mostly;
181static bool pcpu_atomic_alloc_failed;
182
183static void pcpu_schedule_balance_work(void)
184{
185 if (pcpu_async_enabled)
186 schedule_work(&pcpu_balance_work);
187}
188
189/**
190 * pcpu_addr_in_chunk - check if the address is served from this chunk
191 * @chunk: chunk of interest
192 * @addr: percpu address
193 *
194 * RETURNS:
195 * True if the address is served from this chunk.
196 */
197static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
198{
199 void *start_addr, *end_addr;
200
201 if (!chunk)
202 return false;
203
204 start_addr = chunk->base_addr + chunk->start_offset;
205 end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
206 chunk->end_offset;
207
208 return addr >= start_addr && addr < end_addr;
209}
210
211static int __pcpu_size_to_slot(int size)
212{
213 int highbit = fls(size); /* size is in bytes */
214 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
215}
216
217static int pcpu_size_to_slot(int size)
218{
219 if (size == pcpu_unit_size)
220 return pcpu_nr_slots - 1;
221 return __pcpu_size_to_slot(size);
222}
223
224static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
225{
226 if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || chunk->contig_bits == 0)
227 return 0;
228
229 return pcpu_size_to_slot(chunk->free_bytes);
230}
231
232/* set the pointer to a chunk in a page struct */
233static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
234{
235 page->index = (unsigned long)pcpu;
236}
237
238/* obtain pointer to a chunk from a page struct */
239static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
240{
241 return (struct pcpu_chunk *)page->index;
242}
243
244static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
245{
246 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
247}
248
249static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
250{
251 return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
252}
253
254static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
255 unsigned int cpu, int page_idx)
256{
257 return (unsigned long)chunk->base_addr +
258 pcpu_unit_page_offset(cpu, page_idx);
259}
260
261static void pcpu_next_unpop(unsigned long *bitmap, int *rs, int *re, int end)
262{
263 *rs = find_next_zero_bit(bitmap, end, *rs);
264 *re = find_next_bit(bitmap, end, *rs + 1);
265}
266
267static void pcpu_next_pop(unsigned long *bitmap, int *rs, int *re, int end)
268{
269 *rs = find_next_bit(bitmap, end, *rs);
270 *re = find_next_zero_bit(bitmap, end, *rs + 1);
271}
272
273/*
274 * Bitmap region iterators. Iterates over the bitmap between
275 * [@start, @end) in @chunk. @rs and @re should be integer variables
276 * and will be set to start and end index of the current free region.
277 */
278#define pcpu_for_each_unpop_region(bitmap, rs, re, start, end) \
279 for ((rs) = (start), pcpu_next_unpop((bitmap), &(rs), &(re), (end)); \
280 (rs) < (re); \
281 (rs) = (re) + 1, pcpu_next_unpop((bitmap), &(rs), &(re), (end)))
282
283#define pcpu_for_each_pop_region(bitmap, rs, re, start, end) \
284 for ((rs) = (start), pcpu_next_pop((bitmap), &(rs), &(re), (end)); \
285 (rs) < (re); \
286 (rs) = (re) + 1, pcpu_next_pop((bitmap), &(rs), &(re), (end)))
287
288/*
289 * The following are helper functions to help access bitmaps and convert
290 * between bitmap offsets to address offsets.
291 */
292static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
293{
294 return chunk->alloc_map +
295 (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
296}
297
298static unsigned long pcpu_off_to_block_index(int off)
299{
300 return off / PCPU_BITMAP_BLOCK_BITS;
301}
302
303static unsigned long pcpu_off_to_block_off(int off)
304{
305 return off & (PCPU_BITMAP_BLOCK_BITS - 1);
306}
307
308static unsigned long pcpu_block_off_to_off(int index, int off)
309{
310 return index * PCPU_BITMAP_BLOCK_BITS + off;
311}
312
313/**
314 * pcpu_next_md_free_region - finds the next hint free area
315 * @chunk: chunk of interest
316 * @bit_off: chunk offset
317 * @bits: size of free area
318 *
319 * Helper function for pcpu_for_each_md_free_region. It checks
320 * block->contig_hint and performs aggregation across blocks to find the
321 * next hint. It modifies bit_off and bits in-place to be consumed in the
322 * loop.
323 */
324static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
325 int *bits)
326{
327 int i = pcpu_off_to_block_index(*bit_off);
328 int block_off = pcpu_off_to_block_off(*bit_off);
329 struct pcpu_block_md *block;
330
331 *bits = 0;
332 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
333 block++, i++) {
334 /* handles contig area across blocks */
335 if (*bits) {
336 *bits += block->left_free;
337 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
338 continue;
339 return;
340 }
341
342 /*
343 * This checks three things. First is there a contig_hint to
344 * check. Second, have we checked this hint before by
345 * comparing the block_off. Third, is this the same as the
346 * right contig hint. In the last case, it spills over into
347 * the next block and should be handled by the contig area
348 * across blocks code.
349 */
350 *bits = block->contig_hint;
351 if (*bits && block->contig_hint_start >= block_off &&
352 *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
353 *bit_off = pcpu_block_off_to_off(i,
354 block->contig_hint_start);
355 return;
356 }
357 /* reset to satisfy the second predicate above */
358 block_off = 0;
359
360 *bits = block->right_free;
361 *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
362 }
363}
364
365/**
366 * pcpu_next_fit_region - finds fit areas for a given allocation request
367 * @chunk: chunk of interest
368 * @alloc_bits: size of allocation
369 * @align: alignment of area (max PAGE_SIZE)
370 * @bit_off: chunk offset
371 * @bits: size of free area
372 *
373 * Finds the next free region that is viable for use with a given size and
374 * alignment. This only returns if there is a valid area to be used for this
375 * allocation. block->first_free is returned if the allocation request fits
376 * within the block to see if the request can be fulfilled prior to the contig
377 * hint.
378 */
379static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
380 int align, int *bit_off, int *bits)
381{
382 int i = pcpu_off_to_block_index(*bit_off);
383 int block_off = pcpu_off_to_block_off(*bit_off);
384 struct pcpu_block_md *block;
385
386 *bits = 0;
387 for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
388 block++, i++) {
389 /* handles contig area across blocks */
390 if (*bits) {
391 *bits += block->left_free;
392 if (*bits >= alloc_bits)
393 return;
394 if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
395 continue;
396 }
397
398 /* check block->contig_hint */
399 *bits = ALIGN(block->contig_hint_start, align) -
400 block->contig_hint_start;
401 /*
402 * This uses the block offset to determine if this has been
403 * checked in the prior iteration.
404 */
405 if (block->contig_hint &&
406 block->contig_hint_start >= block_off &&
407 block->contig_hint >= *bits + alloc_bits) {
408 *bits += alloc_bits + block->contig_hint_start -
409 block->first_free;
410 *bit_off = pcpu_block_off_to_off(i, block->first_free);
411 return;
412 }
413 /* reset to satisfy the second predicate above */
414 block_off = 0;
415
416 *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
417 align);
418 *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
419 *bit_off = pcpu_block_off_to_off(i, *bit_off);
420 if (*bits >= alloc_bits)
421 return;
422 }
423
424 /* no valid offsets were found - fail condition */
425 *bit_off = pcpu_chunk_map_bits(chunk);
426}
427
428/*
429 * Metadata free area iterators. These perform aggregation of free areas
430 * based on the metadata blocks and return the offset @bit_off and size in
431 * bits of the free area @bits. pcpu_for_each_fit_region only returns when
432 * a fit is found for the allocation request.
433 */
434#define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
435 for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
436 (bit_off) < pcpu_chunk_map_bits((chunk)); \
437 (bit_off) += (bits) + 1, \
438 pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
439
440#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
441 for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
442 &(bits)); \
443 (bit_off) < pcpu_chunk_map_bits((chunk)); \
444 (bit_off) += (bits), \
445 pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
446 &(bits)))
447
448/**
449 * pcpu_mem_zalloc - allocate memory
450 * @size: bytes to allocate
451 * @gfp: allocation flags
452 *
453 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
454 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
455 * This is to facilitate passing through whitelisted flags. The
456 * returned memory is always zeroed.
457 *
458 * RETURNS:
459 * Pointer to the allocated area on success, NULL on failure.
460 */
461static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
462{
463 if (WARN_ON_ONCE(!slab_is_available()))
464 return NULL;
465
466 if (size <= PAGE_SIZE)
467 return kzalloc(size, gfp);
468 else
469 return __vmalloc(size, gfp | __GFP_ZERO, PAGE_KERNEL);
470}
471
472/**
473 * pcpu_mem_free - free memory
474 * @ptr: memory to free
475 *
476 * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
477 */
478static void pcpu_mem_free(void *ptr)
479{
480 kvfree(ptr);
481}
482
483/**
484 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
485 * @chunk: chunk of interest
486 * @oslot: the previous slot it was on
487 *
488 * This function is called after an allocation or free changed @chunk.
489 * New slot according to the changed state is determined and @chunk is
490 * moved to the slot. Note that the reserved chunk is never put on
491 * chunk slots.
492 *
493 * CONTEXT:
494 * pcpu_lock.
495 */
496static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
497{
498 int nslot = pcpu_chunk_slot(chunk);
499
500 if (chunk != pcpu_reserved_chunk && oslot != nslot) {
501 if (oslot < nslot)
502 list_move(&chunk->list, &pcpu_slot[nslot]);
503 else
504 list_move_tail(&chunk->list, &pcpu_slot[nslot]);
505 }
506}
507
508/**
509 * pcpu_cnt_pop_pages- counts populated backing pages in range
510 * @chunk: chunk of interest
511 * @bit_off: start offset
512 * @bits: size of area to check
513 *
514 * Calculates the number of populated pages in the region
515 * [page_start, page_end). This keeps track of how many empty populated
516 * pages are available and decide if async work should be scheduled.
517 *
518 * RETURNS:
519 * The nr of populated pages.
520 */
521static inline int pcpu_cnt_pop_pages(struct pcpu_chunk *chunk, int bit_off,
522 int bits)
523{
524 int page_start = PFN_UP(bit_off * PCPU_MIN_ALLOC_SIZE);
525 int page_end = PFN_DOWN((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
526
527 if (page_start >= page_end)
528 return 0;
529
530 /*
531 * bitmap_weight counts the number of bits set in a bitmap up to
532 * the specified number of bits. This is counting the populated
533 * pages up to page_end and then subtracting the populated pages
534 * up to page_start to count the populated pages in
535 * [page_start, page_end).
536 */
537 return bitmap_weight(chunk->populated, page_end) -
538 bitmap_weight(chunk->populated, page_start);
539}
540
541/**
542 * pcpu_chunk_update - updates the chunk metadata given a free area
543 * @chunk: chunk of interest
544 * @bit_off: chunk offset
545 * @bits: size of free area
546 *
547 * This updates the chunk's contig hint and starting offset given a free area.
548 * Choose the best starting offset if the contig hint is equal.
549 */
550static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits)
551{
552 if (bits > chunk->contig_bits) {
553 chunk->contig_bits_start = bit_off;
554 chunk->contig_bits = bits;
555 } else if (bits == chunk->contig_bits && chunk->contig_bits_start &&
556 (!bit_off ||
557 __ffs(bit_off) > __ffs(chunk->contig_bits_start))) {
558 /* use the start with the best alignment */
559 chunk->contig_bits_start = bit_off;
560 }
561}
562
563/**
564 * pcpu_chunk_refresh_hint - updates metadata about a chunk
565 * @chunk: chunk of interest
566 *
567 * Iterates over the metadata blocks to find the largest contig area.
568 * It also counts the populated pages and uses the delta to update the
569 * global count.
570 *
571 * Updates:
572 * chunk->contig_bits
573 * chunk->contig_bits_start
574 * nr_empty_pop_pages (chunk and global)
575 */
576static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk)
577{
578 int bit_off, bits, nr_empty_pop_pages;
579
580 /* clear metadata */
581 chunk->contig_bits = 0;
582
583 bit_off = chunk->first_bit;
584 bits = nr_empty_pop_pages = 0;
585 pcpu_for_each_md_free_region(chunk, bit_off, bits) {
586 pcpu_chunk_update(chunk, bit_off, bits);
587
588 nr_empty_pop_pages += pcpu_cnt_pop_pages(chunk, bit_off, bits);
589 }
590
591 /*
592 * Keep track of nr_empty_pop_pages.
593 *
594 * The chunk maintains the previous number of free pages it held,
595 * so the delta is used to update the global counter. The reserved
596 * chunk is not part of the free page count as they are populated
597 * at init and are special to serving reserved allocations.
598 */
599 if (chunk != pcpu_reserved_chunk)
600 pcpu_nr_empty_pop_pages +=
601 (nr_empty_pop_pages - chunk->nr_empty_pop_pages);
602
603 chunk->nr_empty_pop_pages = nr_empty_pop_pages;
604}
605
606/**
607 * pcpu_block_update - updates a block given a free area
608 * @block: block of interest
609 * @start: start offset in block
610 * @end: end offset in block
611 *
612 * Updates a block given a known free area. The region [start, end) is
613 * expected to be the entirety of the free area within a block. Chooses
614 * the best starting offset if the contig hints are equal.
615 */
616static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
617{
618 int contig = end - start;
619
620 block->first_free = min(block->first_free, start);
621 if (start == 0)
622 block->left_free = contig;
623
624 if (end == PCPU_BITMAP_BLOCK_BITS)
625 block->right_free = contig;
626
627 if (contig > block->contig_hint) {
628 block->contig_hint_start = start;
629 block->contig_hint = contig;
630 } else if (block->contig_hint_start && contig == block->contig_hint &&
631 (!start || __ffs(start) > __ffs(block->contig_hint_start))) {
632 /* use the start with the best alignment */
633 block->contig_hint_start = start;
634 }
635}
636
637/**
638 * pcpu_block_refresh_hint
639 * @chunk: chunk of interest
640 * @index: index of the metadata block
641 *
642 * Scans over the block beginning at first_free and updates the block
643 * metadata accordingly.
644 */
645static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
646{
647 struct pcpu_block_md *block = chunk->md_blocks + index;
648 unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
649 int rs, re; /* region start, region end */
650
651 /* clear hints */
652 block->contig_hint = 0;
653 block->left_free = block->right_free = 0;
654
655 /* iterate over free areas and update the contig hints */
656 pcpu_for_each_unpop_region(alloc_map, rs, re, block->first_free,
657 PCPU_BITMAP_BLOCK_BITS) {
658 pcpu_block_update(block, rs, re);
659 }
660}
661
662/**
663 * pcpu_block_update_hint_alloc - update hint on allocation path
664 * @chunk: chunk of interest
665 * @bit_off: chunk offset
666 * @bits: size of request
667 *
668 * Updates metadata for the allocation path. The metadata only has to be
669 * refreshed by a full scan iff the chunk's contig hint is broken. Block level
670 * scans are required if the block's contig hint is broken.
671 */
672static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
673 int bits)
674{
675 struct pcpu_block_md *s_block, *e_block, *block;
676 int s_index, e_index; /* block indexes of the freed allocation */
677 int s_off, e_off; /* block offsets of the freed allocation */
678
679 /*
680 * Calculate per block offsets.
681 * The calculation uses an inclusive range, but the resulting offsets
682 * are [start, end). e_index always points to the last block in the
683 * range.
684 */
685 s_index = pcpu_off_to_block_index(bit_off);
686 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
687 s_off = pcpu_off_to_block_off(bit_off);
688 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
689
690 s_block = chunk->md_blocks + s_index;
691 e_block = chunk->md_blocks + e_index;
692
693 /*
694 * Update s_block.
695 * block->first_free must be updated if the allocation takes its place.
696 * If the allocation breaks the contig_hint, a scan is required to
697 * restore this hint.
698 */
699 if (s_off == s_block->first_free)
700 s_block->first_free = find_next_zero_bit(
701 pcpu_index_alloc_map(chunk, s_index),
702 PCPU_BITMAP_BLOCK_BITS,
703 s_off + bits);
704
705 if (s_off >= s_block->contig_hint_start &&
706 s_off < s_block->contig_hint_start + s_block->contig_hint) {
707 /* block contig hint is broken - scan to fix it */
708 pcpu_block_refresh_hint(chunk, s_index);
709 } else {
710 /* update left and right contig manually */
711 s_block->left_free = min(s_block->left_free, s_off);
712 if (s_index == e_index)
713 s_block->right_free = min_t(int, s_block->right_free,
714 PCPU_BITMAP_BLOCK_BITS - e_off);
715 else
716 s_block->right_free = 0;
717 }
718
719 /*
720 * Update e_block.
721 */
722 if (s_index != e_index) {
723 /*
724 * When the allocation is across blocks, the end is along
725 * the left part of the e_block.
726 */
727 e_block->first_free = find_next_zero_bit(
728 pcpu_index_alloc_map(chunk, e_index),
729 PCPU_BITMAP_BLOCK_BITS, e_off);
730
731 if (e_off == PCPU_BITMAP_BLOCK_BITS) {
732 /* reset the block */
733 e_block++;
734 } else {
735 if (e_off > e_block->contig_hint_start) {
736 /* contig hint is broken - scan to fix it */
737 pcpu_block_refresh_hint(chunk, e_index);
738 } else {
739 e_block->left_free = 0;
740 e_block->right_free =
741 min_t(int, e_block->right_free,
742 PCPU_BITMAP_BLOCK_BITS - e_off);
743 }
744 }
745
746 /* update in-between md_blocks */
747 for (block = s_block + 1; block < e_block; block++) {
748 block->contig_hint = 0;
749 block->left_free = 0;
750 block->right_free = 0;
751 }
752 }
753
754 /*
755 * The only time a full chunk scan is required is if the chunk
756 * contig hint is broken. Otherwise, it means a smaller space
757 * was used and therefore the chunk contig hint is still correct.
758 */
759 if (bit_off >= chunk->contig_bits_start &&
760 bit_off < chunk->contig_bits_start + chunk->contig_bits)
761 pcpu_chunk_refresh_hint(chunk);
762}
763
764/**
765 * pcpu_block_update_hint_free - updates the block hints on the free path
766 * @chunk: chunk of interest
767 * @bit_off: chunk offset
768 * @bits: size of request
769 *
770 * Updates metadata for the allocation path. This avoids a blind block
771 * refresh by making use of the block contig hints. If this fails, it scans
772 * forward and backward to determine the extent of the free area. This is
773 * capped at the boundary of blocks.
774 *
775 * A chunk update is triggered if a page becomes free, a block becomes free,
776 * or the free spans across blocks. This tradeoff is to minimize iterating
777 * over the block metadata to update chunk->contig_bits. chunk->contig_bits
778 * may be off by up to a page, but it will never be more than the available
779 * space. If the contig hint is contained in one block, it will be accurate.
780 */
781static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
782 int bits)
783{
784 struct pcpu_block_md *s_block, *e_block, *block;
785 int s_index, e_index; /* block indexes of the freed allocation */
786 int s_off, e_off; /* block offsets of the freed allocation */
787 int start, end; /* start and end of the whole free area */
788
789 /*
790 * Calculate per block offsets.
791 * The calculation uses an inclusive range, but the resulting offsets
792 * are [start, end). e_index always points to the last block in the
793 * range.
794 */
795 s_index = pcpu_off_to_block_index(bit_off);
796 e_index = pcpu_off_to_block_index(bit_off + bits - 1);
797 s_off = pcpu_off_to_block_off(bit_off);
798 e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
799
800 s_block = chunk->md_blocks + s_index;
801 e_block = chunk->md_blocks + e_index;
802
803 /*
804 * Check if the freed area aligns with the block->contig_hint.
805 * If it does, then the scan to find the beginning/end of the
806 * larger free area can be avoided.
807 *
808 * start and end refer to beginning and end of the free area
809 * within each their respective blocks. This is not necessarily
810 * the entire free area as it may span blocks past the beginning
811 * or end of the block.
812 */
813 start = s_off;
814 if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
815 start = s_block->contig_hint_start;
816 } else {
817 /*
818 * Scan backwards to find the extent of the free area.
819 * find_last_bit returns the starting bit, so if the start bit
820 * is returned, that means there was no last bit and the
821 * remainder of the chunk is free.
822 */
823 int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
824 start);
825 start = (start == l_bit) ? 0 : l_bit + 1;
826 }
827
828 end = e_off;
829 if (e_off == e_block->contig_hint_start)
830 end = e_block->contig_hint_start + e_block->contig_hint;
831 else
832 end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
833 PCPU_BITMAP_BLOCK_BITS, end);
834
835 /* update s_block */
836 e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
837 pcpu_block_update(s_block, start, e_off);
838
839 /* freeing in the same block */
840 if (s_index != e_index) {
841 /* update e_block */
842 pcpu_block_update(e_block, 0, end);
843
844 /* reset md_blocks in the middle */
845 for (block = s_block + 1; block < e_block; block++) {
846 block->first_free = 0;
847 block->contig_hint_start = 0;
848 block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
849 block->left_free = PCPU_BITMAP_BLOCK_BITS;
850 block->right_free = PCPU_BITMAP_BLOCK_BITS;
851 }
852 }
853
854 /*
855 * Refresh chunk metadata when the free makes a page free, a block
856 * free, or spans across blocks. The contig hint may be off by up to
857 * a page, but if the hint is contained in a block, it will be accurate
858 * with the else condition below.
859 */
860 if ((ALIGN_DOWN(end, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS)) >
861 ALIGN(start, min(PCPU_BITS_PER_PAGE, PCPU_BITMAP_BLOCK_BITS))) ||
862 s_index != e_index)
863 pcpu_chunk_refresh_hint(chunk);
864 else
865 pcpu_chunk_update(chunk, pcpu_block_off_to_off(s_index, start),
866 s_block->contig_hint);
867}
868
869/**
870 * pcpu_is_populated - determines if the region is populated
871 * @chunk: chunk of interest
872 * @bit_off: chunk offset
873 * @bits: size of area
874 * @next_off: return value for the next offset to start searching
875 *
876 * For atomic allocations, check if the backing pages are populated.
877 *
878 * RETURNS:
879 * Bool if the backing pages are populated.
880 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
881 */
882static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
883 int *next_off)
884{
885 int page_start, page_end, rs, re;
886
887 page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
888 page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
889
890 rs = page_start;
891 pcpu_next_unpop(chunk->populated, &rs, &re, page_end);
892 if (rs >= page_end)
893 return true;
894
895 *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
896 return false;
897}
898
899/**
900 * pcpu_find_block_fit - finds the block index to start searching
901 * @chunk: chunk of interest
902 * @alloc_bits: size of request in allocation units
903 * @align: alignment of area (max PAGE_SIZE bytes)
904 * @pop_only: use populated regions only
905 *
906 * Given a chunk and an allocation spec, find the offset to begin searching
907 * for a free region. This iterates over the bitmap metadata blocks to
908 * find an offset that will be guaranteed to fit the requirements. It is
909 * not quite first fit as if the allocation does not fit in the contig hint
910 * of a block or chunk, it is skipped. This errs on the side of caution
911 * to prevent excess iteration. Poor alignment can cause the allocator to
912 * skip over blocks and chunks that have valid free areas.
913 *
914 * RETURNS:
915 * The offset in the bitmap to begin searching.
916 * -1 if no offset is found.
917 */
918static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
919 size_t align, bool pop_only)
920{
921 int bit_off, bits, next_off;
922
923 /*
924 * Check to see if the allocation can fit in the chunk's contig hint.
925 * This is an optimization to prevent scanning by assuming if it
926 * cannot fit in the global hint, there is memory pressure and creating
927 * a new chunk would happen soon.
928 */
929 bit_off = ALIGN(chunk->contig_bits_start, align) -
930 chunk->contig_bits_start;
931 if (bit_off + alloc_bits > chunk->contig_bits)
932 return -1;
933
934 bit_off = chunk->first_bit;
935 bits = 0;
936 pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
937 if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
938 &next_off))
939 break;
940
941 bit_off = next_off;
942 bits = 0;
943 }
944
945 if (bit_off == pcpu_chunk_map_bits(chunk))
946 return -1;
947
948 return bit_off;
949}
950
951/**
952 * pcpu_alloc_area - allocates an area from a pcpu_chunk
953 * @chunk: chunk of interest
954 * @alloc_bits: size of request in allocation units
955 * @align: alignment of area (max PAGE_SIZE)
956 * @start: bit_off to start searching
957 *
958 * This function takes in a @start offset to begin searching to fit an
959 * allocation of @alloc_bits with alignment @align. It needs to scan
960 * the allocation map because if it fits within the block's contig hint,
961 * @start will be block->first_free. This is an attempt to fill the
962 * allocation prior to breaking the contig hint. The allocation and
963 * boundary maps are updated accordingly if it confirms a valid
964 * free area.
965 *
966 * RETURNS:
967 * Allocated addr offset in @chunk on success.
968 * -1 if no matching area is found.
969 */
970static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
971 size_t align, int start)
972{
973 size_t align_mask = (align) ? (align - 1) : 0;
974 int bit_off, end, oslot;
975
976 lockdep_assert_held(&pcpu_lock);
977
978 oslot = pcpu_chunk_slot(chunk);
979
980 /*
981 * Search to find a fit.
982 */
983 end = start + alloc_bits + PCPU_BITMAP_BLOCK_BITS;
984 bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start,
985 alloc_bits, align_mask);
986 if (bit_off >= end)
987 return -1;
988
989 /* update alloc map */
990 bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
991
992 /* update boundary map */
993 set_bit(bit_off, chunk->bound_map);
994 bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
995 set_bit(bit_off + alloc_bits, chunk->bound_map);
996
997 chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
998
999 /* update first free bit */
1000 if (bit_off == chunk->first_bit)
1001 chunk->first_bit = find_next_zero_bit(
1002 chunk->alloc_map,
1003 pcpu_chunk_map_bits(chunk),
1004 bit_off + alloc_bits);
1005
1006 pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1007
1008 pcpu_chunk_relocate(chunk, oslot);
1009
1010 return bit_off * PCPU_MIN_ALLOC_SIZE;
1011}
1012
1013/**
1014 * pcpu_free_area - frees the corresponding offset
1015 * @chunk: chunk of interest
1016 * @off: addr offset into chunk
1017 *
1018 * This function determines the size of an allocation to free using
1019 * the boundary bitmap and clears the allocation map.
1020 */
1021static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
1022{
1023 int bit_off, bits, end, oslot;
1024
1025 lockdep_assert_held(&pcpu_lock);
1026 pcpu_stats_area_dealloc(chunk);
1027
1028 oslot = pcpu_chunk_slot(chunk);
1029
1030 bit_off = off / PCPU_MIN_ALLOC_SIZE;
1031
1032 /* find end index */
1033 end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1034 bit_off + 1);
1035 bits = end - bit_off;
1036 bitmap_clear(chunk->alloc_map, bit_off, bits);
1037
1038 /* update metadata */
1039 chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE;
1040
1041 /* update first free bit */
1042 chunk->first_bit = min(chunk->first_bit, bit_off);
1043
1044 pcpu_block_update_hint_free(chunk, bit_off, bits);
1045
1046 pcpu_chunk_relocate(chunk, oslot);
1047}
1048
1049static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1050{
1051 struct pcpu_block_md *md_block;
1052
1053 for (md_block = chunk->md_blocks;
1054 md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1055 md_block++) {
1056 md_block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
1057 md_block->left_free = PCPU_BITMAP_BLOCK_BITS;
1058 md_block->right_free = PCPU_BITMAP_BLOCK_BITS;
1059 }
1060}
1061
1062/**
1063 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1064 * @tmp_addr: the start of the region served
1065 * @map_size: size of the region served
1066 *
1067 * This is responsible for creating the chunks that serve the first chunk. The
1068 * base_addr is page aligned down of @tmp_addr while the region end is page
1069 * aligned up. Offsets are kept track of to determine the region served. All
1070 * this is done to appease the bitmap allocator in avoiding partial blocks.
1071 *
1072 * RETURNS:
1073 * Chunk serving the region at @tmp_addr of @map_size.
1074 */
1075static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1076 int map_size)
1077{
1078 struct pcpu_chunk *chunk;
1079 unsigned long aligned_addr, lcm_align;
1080 int start_offset, offset_bits, region_size, region_bits;
1081
1082 /* region calculations */
1083 aligned_addr = tmp_addr & PAGE_MASK;
1084
1085 start_offset = tmp_addr - aligned_addr;
1086
1087 /*
1088 * Align the end of the region with the LCM of PAGE_SIZE and
1089 * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of
1090 * the other.
1091 */
1092 lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
1093 region_size = ALIGN(start_offset + map_size, lcm_align);
1094
1095 /* allocate chunk */
1096 chunk = memblock_virt_alloc(sizeof(struct pcpu_chunk) +
1097 BITS_TO_LONGS(region_size >> PAGE_SHIFT),
1098 0);
1099
1100 INIT_LIST_HEAD(&chunk->list);
1101
1102 chunk->base_addr = (void *)aligned_addr;
1103 chunk->start_offset = start_offset;
1104 chunk->end_offset = region_size - chunk->start_offset - map_size;
1105
1106 chunk->nr_pages = region_size >> PAGE_SHIFT;
1107 region_bits = pcpu_chunk_map_bits(chunk);
1108
1109 chunk->alloc_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits) *
1110 sizeof(chunk->alloc_map[0]), 0);
1111 chunk->bound_map = memblock_virt_alloc(BITS_TO_LONGS(region_bits + 1) *
1112 sizeof(chunk->bound_map[0]), 0);
1113 chunk->md_blocks = memblock_virt_alloc(pcpu_chunk_nr_blocks(chunk) *
1114 sizeof(chunk->md_blocks[0]), 0);
1115 pcpu_init_md_blocks(chunk);
1116
1117 /* manage populated page bitmap */
1118 chunk->immutable = true;
1119 bitmap_fill(chunk->populated, chunk->nr_pages);
1120 chunk->nr_populated = chunk->nr_pages;
1121 chunk->nr_empty_pop_pages =
1122 pcpu_cnt_pop_pages(chunk, start_offset / PCPU_MIN_ALLOC_SIZE,
1123 map_size / PCPU_MIN_ALLOC_SIZE);
1124
1125 chunk->contig_bits = map_size / PCPU_MIN_ALLOC_SIZE;
1126 chunk->free_bytes = map_size;
1127
1128 if (chunk->start_offset) {
1129 /* hide the beginning of the bitmap */
1130 offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1131 bitmap_set(chunk->alloc_map, 0, offset_bits);
1132 set_bit(0, chunk->bound_map);
1133 set_bit(offset_bits, chunk->bound_map);
1134
1135 chunk->first_bit = offset_bits;
1136
1137 pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1138 }
1139
1140 if (chunk->end_offset) {
1141 /* hide the end of the bitmap */
1142 offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1143 bitmap_set(chunk->alloc_map,
1144 pcpu_chunk_map_bits(chunk) - offset_bits,
1145 offset_bits);
1146 set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1147 chunk->bound_map);
1148 set_bit(region_bits, chunk->bound_map);
1149
1150 pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1151 - offset_bits, offset_bits);
1152 }
1153
1154 return chunk;
1155}
1156
1157static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
1158{
1159 struct pcpu_chunk *chunk;
1160 int region_bits;
1161
1162 chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1163 if (!chunk)
1164 return NULL;
1165
1166 INIT_LIST_HEAD(&chunk->list);
1167 chunk->nr_pages = pcpu_unit_pages;
1168 region_bits = pcpu_chunk_map_bits(chunk);
1169
1170 chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1171 sizeof(chunk->alloc_map[0]), gfp);
1172 if (!chunk->alloc_map)
1173 goto alloc_map_fail;
1174
1175 chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1176 sizeof(chunk->bound_map[0]), gfp);
1177 if (!chunk->bound_map)
1178 goto bound_map_fail;
1179
1180 chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1181 sizeof(chunk->md_blocks[0]), gfp);
1182 if (!chunk->md_blocks)
1183 goto md_blocks_fail;
1184
1185 pcpu_init_md_blocks(chunk);
1186
1187 /* init metadata */
1188 chunk->contig_bits = region_bits;
1189 chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1190
1191 return chunk;
1192
1193md_blocks_fail:
1194 pcpu_mem_free(chunk->bound_map);
1195bound_map_fail:
1196 pcpu_mem_free(chunk->alloc_map);
1197alloc_map_fail:
1198 pcpu_mem_free(chunk);
1199
1200 return NULL;
1201}
1202
1203static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1204{
1205 if (!chunk)
1206 return;
1207 pcpu_mem_free(chunk->bound_map);
1208 pcpu_mem_free(chunk->alloc_map);
1209 pcpu_mem_free(chunk);
1210}
1211
1212/**
1213 * pcpu_chunk_populated - post-population bookkeeping
1214 * @chunk: pcpu_chunk which got populated
1215 * @page_start: the start page
1216 * @page_end: the end page
1217 * @for_alloc: if this is to populate for allocation
1218 *
1219 * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1220 * the bookkeeping information accordingly. Must be called after each
1221 * successful population.
1222 *
1223 * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it
1224 * is to serve an allocation in that area.
1225 */
1226static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1227 int page_end, bool for_alloc)
1228{
1229 int nr = page_end - page_start;
1230
1231 lockdep_assert_held(&pcpu_lock);
1232
1233 bitmap_set(chunk->populated, page_start, nr);
1234 chunk->nr_populated += nr;
1235
1236 if (!for_alloc) {
1237 chunk->nr_empty_pop_pages += nr;
1238 pcpu_nr_empty_pop_pages += nr;
1239 }
1240}
1241
1242/**
1243 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1244 * @chunk: pcpu_chunk which got depopulated
1245 * @page_start: the start page
1246 * @page_end: the end page
1247 *
1248 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1249 * Update the bookkeeping information accordingly. Must be called after
1250 * each successful depopulation.
1251 */
1252static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1253 int page_start, int page_end)
1254{
1255 int nr = page_end - page_start;
1256
1257 lockdep_assert_held(&pcpu_lock);
1258
1259 bitmap_clear(chunk->populated, page_start, nr);
1260 chunk->nr_populated -= nr;
1261 chunk->nr_empty_pop_pages -= nr;
1262 pcpu_nr_empty_pop_pages -= nr;
1263}
1264
1265/*
1266 * Chunk management implementation.
1267 *
1268 * To allow different implementations, chunk alloc/free and
1269 * [de]population are implemented in a separate file which is pulled
1270 * into this file and compiled together. The following functions
1271 * should be implemented.
1272 *
1273 * pcpu_populate_chunk - populate the specified range of a chunk
1274 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1275 * pcpu_create_chunk - create a new chunk
1276 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1277 * pcpu_addr_to_page - translate address to physical address
1278 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1279 */
1280static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1281 int page_start, int page_end, gfp_t gfp);
1282static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1283 int page_start, int page_end);
1284static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
1285static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1286static struct page *pcpu_addr_to_page(void *addr);
1287static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1288
1289#ifdef CONFIG_NEED_PER_CPU_KM
1290#include "percpu-km.c"
1291#else
1292#include "percpu-vm.c"
1293#endif
1294
1295/**
1296 * pcpu_chunk_addr_search - determine chunk containing specified address
1297 * @addr: address for which the chunk needs to be determined.
1298 *
1299 * This is an internal function that handles all but static allocations.
1300 * Static percpu address values should never be passed into the allocator.
1301 *
1302 * RETURNS:
1303 * The address of the found chunk.
1304 */
1305static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1306{
1307 /* is it in the dynamic region (first chunk)? */
1308 if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1309 return pcpu_first_chunk;
1310
1311 /* is it in the reserved region? */
1312 if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1313 return pcpu_reserved_chunk;
1314
1315 /*
1316 * The address is relative to unit0 which might be unused and
1317 * thus unmapped. Offset the address to the unit space of the
1318 * current processor before looking it up in the vmalloc
1319 * space. Note that any possible cpu id can be used here, so
1320 * there's no need to worry about preemption or cpu hotplug.
1321 */
1322 addr += pcpu_unit_offsets[raw_smp_processor_id()];
1323 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1324}
1325
1326/**
1327 * pcpu_alloc - the percpu allocator
1328 * @size: size of area to allocate in bytes
1329 * @align: alignment of area (max PAGE_SIZE)
1330 * @reserved: allocate from the reserved chunk if available
1331 * @gfp: allocation flags
1332 *
1333 * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1334 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1335 * then no warning will be triggered on invalid or failed allocation
1336 * requests.
1337 *
1338 * RETURNS:
1339 * Percpu pointer to the allocated area on success, NULL on failure.
1340 */
1341static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1342 gfp_t gfp)
1343{
1344 /* whitelisted flags that can be passed to the backing allocators */
1345 gfp_t pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1346 bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1347 bool do_warn = !(gfp & __GFP_NOWARN);
1348 static int warn_limit = 10;
1349 struct pcpu_chunk *chunk;
1350 const char *err;
1351 int slot, off, cpu, ret;
1352 unsigned long flags;
1353 void __percpu *ptr;
1354 size_t bits, bit_align;
1355
1356 /*
1357 * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1358 * therefore alignment must be a minimum of that many bytes.
1359 * An allocation may have internal fragmentation from rounding up
1360 * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1361 */
1362 if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1363 align = PCPU_MIN_ALLOC_SIZE;
1364
1365 size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1366 bits = size >> PCPU_MIN_ALLOC_SHIFT;
1367 bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1368
1369 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1370 !is_power_of_2(align))) {
1371 WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1372 size, align);
1373 return NULL;
1374 }
1375
1376 if (!is_atomic) {
1377 /*
1378 * pcpu_balance_workfn() allocates memory under this mutex,
1379 * and it may wait for memory reclaim. Allow current task
1380 * to become OOM victim, in case of memory pressure.
1381 */
1382 if (gfp & __GFP_NOFAIL)
1383 mutex_lock(&pcpu_alloc_mutex);
1384 else if (mutex_lock_killable(&pcpu_alloc_mutex))
1385 return NULL;
1386 }
1387
1388 spin_lock_irqsave(&pcpu_lock, flags);
1389
1390 /* serve reserved allocations from the reserved chunk if available */
1391 if (reserved && pcpu_reserved_chunk) {
1392 chunk = pcpu_reserved_chunk;
1393
1394 off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1395 if (off < 0) {
1396 err = "alloc from reserved chunk failed";
1397 goto fail_unlock;
1398 }
1399
1400 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1401 if (off >= 0)
1402 goto area_found;
1403
1404 err = "alloc from reserved chunk failed";
1405 goto fail_unlock;
1406 }
1407
1408restart:
1409 /* search through normal chunks */
1410 for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
1411 list_for_each_entry(chunk, &pcpu_slot[slot], list) {
1412 off = pcpu_find_block_fit(chunk, bits, bit_align,
1413 is_atomic);
1414 if (off < 0)
1415 continue;
1416
1417 off = pcpu_alloc_area(chunk, bits, bit_align, off);
1418 if (off >= 0)
1419 goto area_found;
1420
1421 }
1422 }
1423
1424 spin_unlock_irqrestore(&pcpu_lock, flags);
1425
1426 /*
1427 * No space left. Create a new chunk. We don't want multiple
1428 * tasks to create chunks simultaneously. Serialize and create iff
1429 * there's still no empty chunk after grabbing the mutex.
1430 */
1431 if (is_atomic) {
1432 err = "atomic alloc failed, no space left";
1433 goto fail;
1434 }
1435
1436 if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
1437 chunk = pcpu_create_chunk(pcpu_gfp);
1438 if (!chunk) {
1439 err = "failed to allocate new chunk";
1440 goto fail;
1441 }
1442
1443 spin_lock_irqsave(&pcpu_lock, flags);
1444 pcpu_chunk_relocate(chunk, -1);
1445 } else {
1446 spin_lock_irqsave(&pcpu_lock, flags);
1447 }
1448
1449 goto restart;
1450
1451area_found:
1452 pcpu_stats_area_alloc(chunk, size);
1453 spin_unlock_irqrestore(&pcpu_lock, flags);
1454
1455 /* populate if not all pages are already there */
1456 if (!is_atomic) {
1457 int page_start, page_end, rs, re;
1458
1459 page_start = PFN_DOWN(off);
1460 page_end = PFN_UP(off + size);
1461
1462 pcpu_for_each_unpop_region(chunk->populated, rs, re,
1463 page_start, page_end) {
1464 WARN_ON(chunk->immutable);
1465
1466 ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1467
1468 spin_lock_irqsave(&pcpu_lock, flags);
1469 if (ret) {
1470 pcpu_free_area(chunk, off);
1471 err = "failed to populate";
1472 goto fail_unlock;
1473 }
1474 pcpu_chunk_populated(chunk, rs, re, true);
1475 spin_unlock_irqrestore(&pcpu_lock, flags);
1476 }
1477
1478 mutex_unlock(&pcpu_alloc_mutex);
1479 }
1480
1481 if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1482 pcpu_schedule_balance_work();
1483
1484 /* clear the areas and return address relative to base address */
1485 for_each_possible_cpu(cpu)
1486 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1487
1488 ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1489 kmemleak_alloc_percpu(ptr, size, gfp);
1490
1491 trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
1492 chunk->base_addr, off, ptr);
1493
1494 return ptr;
1495
1496fail_unlock:
1497 spin_unlock_irqrestore(&pcpu_lock, flags);
1498fail:
1499 trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1500
1501 if (!is_atomic && do_warn && warn_limit) {
1502 pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1503 size, align, is_atomic, err);
1504 dump_stack();
1505 if (!--warn_limit)
1506 pr_info("limit reached, disable warning\n");
1507 }
1508 if (is_atomic) {
1509 /* see the flag handling in pcpu_blance_workfn() */
1510 pcpu_atomic_alloc_failed = true;
1511 pcpu_schedule_balance_work();
1512 } else {
1513 mutex_unlock(&pcpu_alloc_mutex);
1514 }
1515 return NULL;
1516}
1517
1518/**
1519 * __alloc_percpu_gfp - allocate dynamic percpu area
1520 * @size: size of area to allocate in bytes
1521 * @align: alignment of area (max PAGE_SIZE)
1522 * @gfp: allocation flags
1523 *
1524 * Allocate zero-filled percpu area of @size bytes aligned at @align. If
1525 * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1526 * be called from any context but is a lot more likely to fail. If @gfp
1527 * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1528 * allocation requests.
1529 *
1530 * RETURNS:
1531 * Percpu pointer to the allocated area on success, NULL on failure.
1532 */
1533void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1534{
1535 return pcpu_alloc(size, align, false, gfp);
1536}
1537EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1538
1539/**
1540 * __alloc_percpu - allocate dynamic percpu area
1541 * @size: size of area to allocate in bytes
1542 * @align: alignment of area (max PAGE_SIZE)
1543 *
1544 * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1545 */
1546void __percpu *__alloc_percpu(size_t size, size_t align)
1547{
1548 return pcpu_alloc(size, align, false, GFP_KERNEL);
1549}
1550EXPORT_SYMBOL_GPL(__alloc_percpu);
1551
1552/**
1553 * __alloc_reserved_percpu - allocate reserved percpu area
1554 * @size: size of area to allocate in bytes
1555 * @align: alignment of area (max PAGE_SIZE)
1556 *
1557 * Allocate zero-filled percpu area of @size bytes aligned at @align
1558 * from reserved percpu area if arch has set it up; otherwise,
1559 * allocation is served from the same dynamic area. Might sleep.
1560 * Might trigger writeouts.
1561 *
1562 * CONTEXT:
1563 * Does GFP_KERNEL allocation.
1564 *
1565 * RETURNS:
1566 * Percpu pointer to the allocated area on success, NULL on failure.
1567 */
1568void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1569{
1570 return pcpu_alloc(size, align, true, GFP_KERNEL);
1571}
1572
1573/**
1574 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
1575 * @work: unused
1576 *
1577 * Reclaim all fully free chunks except for the first one. This is also
1578 * responsible for maintaining the pool of empty populated pages. However,
1579 * it is possible that this is called when physical memory is scarce causing
1580 * OOM killer to be triggered. We should avoid doing so until an actual
1581 * allocation causes the failure as it is possible that requests can be
1582 * serviced from already backed regions.
1583 */
1584static void pcpu_balance_workfn(struct work_struct *work)
1585{
1586 /* gfp flags passed to underlying allocators */
1587 const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
1588 LIST_HEAD(to_free);
1589 struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
1590 struct pcpu_chunk *chunk, *next;
1591 int slot, nr_to_pop, ret;
1592
1593 /*
1594 * There's no reason to keep around multiple unused chunks and VM
1595 * areas can be scarce. Destroy all free chunks except for one.
1596 */
1597 mutex_lock(&pcpu_alloc_mutex);
1598 spin_lock_irq(&pcpu_lock);
1599
1600 list_for_each_entry_safe(chunk, next, free_head, list) {
1601 WARN_ON(chunk->immutable);
1602
1603 /* spare the first one */
1604 if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1605 continue;
1606
1607 list_move(&chunk->list, &to_free);
1608 }
1609
1610 spin_unlock_irq(&pcpu_lock);
1611
1612 list_for_each_entry_safe(chunk, next, &to_free, list) {
1613 int rs, re;
1614
1615 pcpu_for_each_pop_region(chunk->populated, rs, re, 0,
1616 chunk->nr_pages) {
1617 pcpu_depopulate_chunk(chunk, rs, re);
1618 spin_lock_irq(&pcpu_lock);
1619 pcpu_chunk_depopulated(chunk, rs, re);
1620 spin_unlock_irq(&pcpu_lock);
1621 }
1622 pcpu_destroy_chunk(chunk);
1623 cond_resched();
1624 }
1625
1626 /*
1627 * Ensure there are certain number of free populated pages for
1628 * atomic allocs. Fill up from the most packed so that atomic
1629 * allocs don't increase fragmentation. If atomic allocation
1630 * failed previously, always populate the maximum amount. This
1631 * should prevent atomic allocs larger than PAGE_SIZE from keeping
1632 * failing indefinitely; however, large atomic allocs are not
1633 * something we support properly and can be highly unreliable and
1634 * inefficient.
1635 */
1636retry_pop:
1637 if (pcpu_atomic_alloc_failed) {
1638 nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
1639 /* best effort anyway, don't worry about synchronization */
1640 pcpu_atomic_alloc_failed = false;
1641 } else {
1642 nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
1643 pcpu_nr_empty_pop_pages,
1644 0, PCPU_EMPTY_POP_PAGES_HIGH);
1645 }
1646
1647 for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
1648 int nr_unpop = 0, rs, re;
1649
1650 if (!nr_to_pop)
1651 break;
1652
1653 spin_lock_irq(&pcpu_lock);
1654 list_for_each_entry(chunk, &pcpu_slot[slot], list) {
1655 nr_unpop = chunk->nr_pages - chunk->nr_populated;
1656 if (nr_unpop)
1657 break;
1658 }
1659 spin_unlock_irq(&pcpu_lock);
1660
1661 if (!nr_unpop)
1662 continue;
1663
1664 /* @chunk can't go away while pcpu_alloc_mutex is held */
1665 pcpu_for_each_unpop_region(chunk->populated, rs, re, 0,
1666 chunk->nr_pages) {
1667 int nr = min(re - rs, nr_to_pop);
1668
1669 ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
1670 if (!ret) {
1671 nr_to_pop -= nr;
1672 spin_lock_irq(&pcpu_lock);
1673 pcpu_chunk_populated(chunk, rs, rs + nr, false);
1674 spin_unlock_irq(&pcpu_lock);
1675 } else {
1676 nr_to_pop = 0;
1677 }
1678
1679 if (!nr_to_pop)
1680 break;
1681 }
1682 }
1683
1684 if (nr_to_pop) {
1685 /* ran out of chunks to populate, create a new one and retry */
1686 chunk = pcpu_create_chunk(gfp);
1687 if (chunk) {
1688 spin_lock_irq(&pcpu_lock);
1689 pcpu_chunk_relocate(chunk, -1);
1690 spin_unlock_irq(&pcpu_lock);
1691 goto retry_pop;
1692 }
1693 }
1694
1695 mutex_unlock(&pcpu_alloc_mutex);
1696}
1697
1698/**
1699 * free_percpu - free percpu area
1700 * @ptr: pointer to area to free
1701 *
1702 * Free percpu area @ptr.
1703 *
1704 * CONTEXT:
1705 * Can be called from atomic context.
1706 */
1707void free_percpu(void __percpu *ptr)
1708{
1709 void *addr;
1710 struct pcpu_chunk *chunk;
1711 unsigned long flags;
1712 int off;
1713
1714 if (!ptr)
1715 return;
1716
1717 kmemleak_free_percpu(ptr);
1718
1719 addr = __pcpu_ptr_to_addr(ptr);
1720
1721 spin_lock_irqsave(&pcpu_lock, flags);
1722
1723 chunk = pcpu_chunk_addr_search(addr);
1724 off = addr - chunk->base_addr;
1725
1726 pcpu_free_area(chunk, off);
1727
1728 /* if there are more than one fully free chunks, wake up grim reaper */
1729 if (chunk->free_bytes == pcpu_unit_size) {
1730 struct pcpu_chunk *pos;
1731
1732 list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
1733 if (pos != chunk) {
1734 pcpu_schedule_balance_work();
1735 break;
1736 }
1737 }
1738
1739 trace_percpu_free_percpu(chunk->base_addr, off, ptr);
1740
1741 spin_unlock_irqrestore(&pcpu_lock, flags);
1742}
1743EXPORT_SYMBOL_GPL(free_percpu);
1744
1745bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
1746{
1747#ifdef CONFIG_SMP
1748 const size_t static_size = __per_cpu_end - __per_cpu_start;
1749 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
1750 unsigned int cpu;
1751
1752 for_each_possible_cpu(cpu) {
1753 void *start = per_cpu_ptr(base, cpu);
1754 void *va = (void *)addr;
1755
1756 if (va >= start && va < start + static_size) {
1757 if (can_addr) {
1758 *can_addr = (unsigned long) (va - start);
1759 *can_addr += (unsigned long)
1760 per_cpu_ptr(base, get_boot_cpu_id());
1761 }
1762 return true;
1763 }
1764 }
1765#endif
1766 /* on UP, can't distinguish from other static vars, always false */
1767 return false;
1768}
1769
1770/**
1771 * is_kernel_percpu_address - test whether address is from static percpu area
1772 * @addr: address to test
1773 *
1774 * Test whether @addr belongs to in-kernel static percpu area. Module
1775 * static percpu areas are not considered. For those, use
1776 * is_module_percpu_address().
1777 *
1778 * RETURNS:
1779 * %true if @addr is from in-kernel static percpu area, %false otherwise.
1780 */
1781bool is_kernel_percpu_address(unsigned long addr)
1782{
1783 return __is_kernel_percpu_address(addr, NULL);
1784}
1785
1786/**
1787 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
1788 * @addr: the address to be converted to physical address
1789 *
1790 * Given @addr which is dereferenceable address obtained via one of
1791 * percpu access macros, this function translates it into its physical
1792 * address. The caller is responsible for ensuring @addr stays valid
1793 * until this function finishes.
1794 *
1795 * percpu allocator has special setup for the first chunk, which currently
1796 * supports either embedding in linear address space or vmalloc mapping,
1797 * and, from the second one, the backing allocator (currently either vm or
1798 * km) provides translation.
1799 *
1800 * The addr can be translated simply without checking if it falls into the
1801 * first chunk. But the current code reflects better how percpu allocator
1802 * actually works, and the verification can discover both bugs in percpu
1803 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
1804 * code.
1805 *
1806 * RETURNS:
1807 * The physical address for @addr.
1808 */
1809phys_addr_t per_cpu_ptr_to_phys(void *addr)
1810{
1811 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
1812 bool in_first_chunk = false;
1813 unsigned long first_low, first_high;
1814 unsigned int cpu;
1815
1816 /*
1817 * The following test on unit_low/high isn't strictly
1818 * necessary but will speed up lookups of addresses which
1819 * aren't in the first chunk.
1820 *
1821 * The address check is against full chunk sizes. pcpu_base_addr
1822 * points to the beginning of the first chunk including the
1823 * static region. Assumes good intent as the first chunk may
1824 * not be full (ie. < pcpu_unit_pages in size).
1825 */
1826 first_low = (unsigned long)pcpu_base_addr +
1827 pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
1828 first_high = (unsigned long)pcpu_base_addr +
1829 pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
1830 if ((unsigned long)addr >= first_low &&
1831 (unsigned long)addr < first_high) {
1832 for_each_possible_cpu(cpu) {
1833 void *start = per_cpu_ptr(base, cpu);
1834
1835 if (addr >= start && addr < start + pcpu_unit_size) {
1836 in_first_chunk = true;
1837 break;
1838 }
1839 }
1840 }
1841
1842 if (in_first_chunk) {
1843 if (!is_vmalloc_addr(addr))
1844 return __pa(addr);
1845 else
1846 return page_to_phys(vmalloc_to_page(addr)) +
1847 offset_in_page(addr);
1848 } else
1849 return page_to_phys(pcpu_addr_to_page(addr)) +
1850 offset_in_page(addr);
1851}
1852
1853/**
1854 * pcpu_alloc_alloc_info - allocate percpu allocation info
1855 * @nr_groups: the number of groups
1856 * @nr_units: the number of units
1857 *
1858 * Allocate ai which is large enough for @nr_groups groups containing
1859 * @nr_units units. The returned ai's groups[0].cpu_map points to the
1860 * cpu_map array which is long enough for @nr_units and filled with
1861 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
1862 * pointer of other groups.
1863 *
1864 * RETURNS:
1865 * Pointer to the allocated pcpu_alloc_info on success, NULL on
1866 * failure.
1867 */
1868struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
1869 int nr_units)
1870{
1871 struct pcpu_alloc_info *ai;
1872 size_t base_size, ai_size;
1873 void *ptr;
1874 int unit;
1875
1876 base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]),
1877 __alignof__(ai->groups[0].cpu_map[0]));
1878 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
1879
1880 ptr = memblock_virt_alloc_nopanic(PFN_ALIGN(ai_size), PAGE_SIZE);
1881 if (!ptr)
1882 return NULL;
1883 ai = ptr;
1884 ptr += base_size;
1885
1886 ai->groups[0].cpu_map = ptr;
1887
1888 for (unit = 0; unit < nr_units; unit++)
1889 ai->groups[0].cpu_map[unit] = NR_CPUS;
1890
1891 ai->nr_groups = nr_groups;
1892 ai->__ai_size = PFN_ALIGN(ai_size);
1893
1894 return ai;
1895}
1896
1897/**
1898 * pcpu_free_alloc_info - free percpu allocation info
1899 * @ai: pcpu_alloc_info to free
1900 *
1901 * Free @ai which was allocated by pcpu_alloc_alloc_info().
1902 */
1903void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
1904{
1905 memblock_free_early(__pa(ai), ai->__ai_size);
1906}
1907
1908/**
1909 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
1910 * @lvl: loglevel
1911 * @ai: allocation info to dump
1912 *
1913 * Print out information about @ai using loglevel @lvl.
1914 */
1915static void pcpu_dump_alloc_info(const char *lvl,
1916 const struct pcpu_alloc_info *ai)
1917{
1918 int group_width = 1, cpu_width = 1, width;
1919 char empty_str[] = "--------";
1920 int alloc = 0, alloc_end = 0;
1921 int group, v;
1922 int upa, apl; /* units per alloc, allocs per line */
1923
1924 v = ai->nr_groups;
1925 while (v /= 10)
1926 group_width++;
1927
1928 v = num_possible_cpus();
1929 while (v /= 10)
1930 cpu_width++;
1931 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
1932
1933 upa = ai->alloc_size / ai->unit_size;
1934 width = upa * (cpu_width + 1) + group_width + 3;
1935 apl = rounddown_pow_of_two(max(60 / width, 1));
1936
1937 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
1938 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
1939 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
1940
1941 for (group = 0; group < ai->nr_groups; group++) {
1942 const struct pcpu_group_info *gi = &ai->groups[group];
1943 int unit = 0, unit_end = 0;
1944
1945 BUG_ON(gi->nr_units % upa);
1946 for (alloc_end += gi->nr_units / upa;
1947 alloc < alloc_end; alloc++) {
1948 if (!(alloc % apl)) {
1949 pr_cont("\n");
1950 printk("%spcpu-alloc: ", lvl);
1951 }
1952 pr_cont("[%0*d] ", group_width, group);
1953
1954 for (unit_end += upa; unit < unit_end; unit++)
1955 if (gi->cpu_map[unit] != NR_CPUS)
1956 pr_cont("%0*d ",
1957 cpu_width, gi->cpu_map[unit]);
1958 else
1959 pr_cont("%s ", empty_str);
1960 }
1961 }
1962 pr_cont("\n");
1963}
1964
1965/**
1966 * pcpu_setup_first_chunk - initialize the first percpu chunk
1967 * @ai: pcpu_alloc_info describing how to percpu area is shaped
1968 * @base_addr: mapped address
1969 *
1970 * Initialize the first percpu chunk which contains the kernel static
1971 * perpcu area. This function is to be called from arch percpu area
1972 * setup path.
1973 *
1974 * @ai contains all information necessary to initialize the first
1975 * chunk and prime the dynamic percpu allocator.
1976 *
1977 * @ai->static_size is the size of static percpu area.
1978 *
1979 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
1980 * reserve after the static area in the first chunk. This reserves
1981 * the first chunk such that it's available only through reserved
1982 * percpu allocation. This is primarily used to serve module percpu
1983 * static areas on architectures where the addressing model has
1984 * limited offset range for symbol relocations to guarantee module
1985 * percpu symbols fall inside the relocatable range.
1986 *
1987 * @ai->dyn_size determines the number of bytes available for dynamic
1988 * allocation in the first chunk. The area between @ai->static_size +
1989 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
1990 *
1991 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
1992 * and equal to or larger than @ai->static_size + @ai->reserved_size +
1993 * @ai->dyn_size.
1994 *
1995 * @ai->atom_size is the allocation atom size and used as alignment
1996 * for vm areas.
1997 *
1998 * @ai->alloc_size is the allocation size and always multiple of
1999 * @ai->atom_size. This is larger than @ai->atom_size if
2000 * @ai->unit_size is larger than @ai->atom_size.
2001 *
2002 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2003 * percpu areas. Units which should be colocated are put into the
2004 * same group. Dynamic VM areas will be allocated according to these
2005 * groupings. If @ai->nr_groups is zero, a single group containing
2006 * all units is assumed.
2007 *
2008 * The caller should have mapped the first chunk at @base_addr and
2009 * copied static data to each unit.
2010 *
2011 * The first chunk will always contain a static and a dynamic region.
2012 * However, the static region is not managed by any chunk. If the first
2013 * chunk also contains a reserved region, it is served by two chunks -
2014 * one for the reserved region and one for the dynamic region. They
2015 * share the same vm, but use offset regions in the area allocation map.
2016 * The chunk serving the dynamic region is circulated in the chunk slots
2017 * and available for dynamic allocation like any other chunk.
2018 *
2019 * RETURNS:
2020 * 0 on success, -errno on failure.
2021 */
2022int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2023 void *base_addr)
2024{
2025 size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2026 size_t static_size, dyn_size;
2027 struct pcpu_chunk *chunk;
2028 unsigned long *group_offsets;
2029 size_t *group_sizes;
2030 unsigned long *unit_off;
2031 unsigned int cpu;
2032 int *unit_map;
2033 int group, unit, i;
2034 int map_size;
2035 unsigned long tmp_addr;
2036
2037#define PCPU_SETUP_BUG_ON(cond) do { \
2038 if (unlikely(cond)) { \
2039 pr_emerg("failed to initialize, %s\n", #cond); \
2040 pr_emerg("cpu_possible_mask=%*pb\n", \
2041 cpumask_pr_args(cpu_possible_mask)); \
2042 pcpu_dump_alloc_info(KERN_EMERG, ai); \
2043 BUG(); \
2044 } \
2045} while (0)
2046
2047 /* sanity checks */
2048 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2049#ifdef CONFIG_SMP
2050 PCPU_SETUP_BUG_ON(!ai->static_size);
2051 PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2052#endif
2053 PCPU_SETUP_BUG_ON(!base_addr);
2054 PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2055 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2056 PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2057 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2058 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2059 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2060 PCPU_SETUP_BUG_ON(!ai->dyn_size);
2061 PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2062 PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2063 IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2064 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2065
2066 /* process group information and build config tables accordingly */
2067 group_offsets = memblock_virt_alloc(ai->nr_groups *
2068 sizeof(group_offsets[0]), 0);
2069 group_sizes = memblock_virt_alloc(ai->nr_groups *
2070 sizeof(group_sizes[0]), 0);
2071 unit_map = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_map[0]), 0);
2072 unit_off = memblock_virt_alloc(nr_cpu_ids * sizeof(unit_off[0]), 0);
2073
2074 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2075 unit_map[cpu] = UINT_MAX;
2076
2077 pcpu_low_unit_cpu = NR_CPUS;
2078 pcpu_high_unit_cpu = NR_CPUS;
2079
2080 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2081 const struct pcpu_group_info *gi = &ai->groups[group];
2082
2083 group_offsets[group] = gi->base_offset;
2084 group_sizes[group] = gi->nr_units * ai->unit_size;
2085
2086 for (i = 0; i < gi->nr_units; i++) {
2087 cpu = gi->cpu_map[i];
2088 if (cpu == NR_CPUS)
2089 continue;
2090
2091 PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2092 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2093 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2094
2095 unit_map[cpu] = unit + i;
2096 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2097
2098 /* determine low/high unit_cpu */
2099 if (pcpu_low_unit_cpu == NR_CPUS ||
2100 unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2101 pcpu_low_unit_cpu = cpu;
2102 if (pcpu_high_unit_cpu == NR_CPUS ||
2103 unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2104 pcpu_high_unit_cpu = cpu;
2105 }
2106 }
2107 pcpu_nr_units = unit;
2108
2109 for_each_possible_cpu(cpu)
2110 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2111
2112 /* we're done parsing the input, undefine BUG macro and dump config */
2113#undef PCPU_SETUP_BUG_ON
2114 pcpu_dump_alloc_info(KERN_DEBUG, ai);
2115
2116 pcpu_nr_groups = ai->nr_groups;
2117 pcpu_group_offsets = group_offsets;
2118 pcpu_group_sizes = group_sizes;
2119 pcpu_unit_map = unit_map;
2120 pcpu_unit_offsets = unit_off;
2121
2122 /* determine basic parameters */
2123 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2124 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2125 pcpu_atom_size = ai->atom_size;
2126 pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
2127 BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
2128
2129 pcpu_stats_save_ai(ai);
2130
2131 /*
2132 * Allocate chunk slots. The additional last slot is for
2133 * empty chunks.
2134 */
2135 pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
2136 pcpu_slot = memblock_virt_alloc(
2137 pcpu_nr_slots * sizeof(pcpu_slot[0]), 0);
2138 for (i = 0; i < pcpu_nr_slots; i++)
2139 INIT_LIST_HEAD(&pcpu_slot[i]);
2140
2141 /*
2142 * The end of the static region needs to be aligned with the
2143 * minimum allocation size as this offsets the reserved and
2144 * dynamic region. The first chunk ends page aligned by
2145 * expanding the dynamic region, therefore the dynamic region
2146 * can be shrunk to compensate while still staying above the
2147 * configured sizes.
2148 */
2149 static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2150 dyn_size = ai->dyn_size - (static_size - ai->static_size);
2151
2152 /*
2153 * Initialize first chunk.
2154 * If the reserved_size is non-zero, this initializes the reserved
2155 * chunk. If the reserved_size is zero, the reserved chunk is NULL
2156 * and the dynamic region is initialized here. The first chunk,
2157 * pcpu_first_chunk, will always point to the chunk that serves
2158 * the dynamic region.
2159 */
2160 tmp_addr = (unsigned long)base_addr + static_size;
2161 map_size = ai->reserved_size ?: dyn_size;
2162 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2163
2164 /* init dynamic chunk if necessary */
2165 if (ai->reserved_size) {
2166 pcpu_reserved_chunk = chunk;
2167
2168 tmp_addr = (unsigned long)base_addr + static_size +
2169 ai->reserved_size;
2170 map_size = dyn_size;
2171 chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2172 }
2173
2174 /* link the first chunk in */
2175 pcpu_first_chunk = chunk;
2176 pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2177 pcpu_chunk_relocate(pcpu_first_chunk, -1);
2178
2179 pcpu_stats_chunk_alloc();
2180 trace_percpu_create_chunk(base_addr);
2181
2182 /* we're done */
2183 pcpu_base_addr = base_addr;
2184 return 0;
2185}
2186
2187#ifdef CONFIG_SMP
2188
2189const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2190 [PCPU_FC_AUTO] = "auto",
2191 [PCPU_FC_EMBED] = "embed",
2192 [PCPU_FC_PAGE] = "page",
2193};
2194
2195enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2196
2197static int __init percpu_alloc_setup(char *str)
2198{
2199 if (!str)
2200 return -EINVAL;
2201
2202 if (0)
2203 /* nada */;
2204#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2205 else if (!strcmp(str, "embed"))
2206 pcpu_chosen_fc = PCPU_FC_EMBED;
2207#endif
2208#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2209 else if (!strcmp(str, "page"))
2210 pcpu_chosen_fc = PCPU_FC_PAGE;
2211#endif
2212 else
2213 pr_warn("unknown allocator %s specified\n", str);
2214
2215 return 0;
2216}
2217early_param("percpu_alloc", percpu_alloc_setup);
2218
2219/*
2220 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2221 * Build it if needed by the arch config or the generic setup is going
2222 * to be used.
2223 */
2224#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2225 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2226#define BUILD_EMBED_FIRST_CHUNK
2227#endif
2228
2229/* build pcpu_page_first_chunk() iff needed by the arch config */
2230#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2231#define BUILD_PAGE_FIRST_CHUNK
2232#endif
2233
2234/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2235#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2236/**
2237 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2238 * @reserved_size: the size of reserved percpu area in bytes
2239 * @dyn_size: minimum free size for dynamic allocation in bytes
2240 * @atom_size: allocation atom size
2241 * @cpu_distance_fn: callback to determine distance between cpus, optional
2242 *
2243 * This function determines grouping of units, their mappings to cpus
2244 * and other parameters considering needed percpu size, allocation
2245 * atom size and distances between CPUs.
2246 *
2247 * Groups are always multiples of atom size and CPUs which are of
2248 * LOCAL_DISTANCE both ways are grouped together and share space for
2249 * units in the same group. The returned configuration is guaranteed
2250 * to have CPUs on different nodes on different groups and >=75% usage
2251 * of allocated virtual address space.
2252 *
2253 * RETURNS:
2254 * On success, pointer to the new allocation_info is returned. On
2255 * failure, ERR_PTR value is returned.
2256 */
2257static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
2258 size_t reserved_size, size_t dyn_size,
2259 size_t atom_size,
2260 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2261{
2262 static int group_map[NR_CPUS] __initdata;
2263 static int group_cnt[NR_CPUS] __initdata;
2264 const size_t static_size = __per_cpu_end - __per_cpu_start;
2265 int nr_groups = 1, nr_units = 0;
2266 size_t size_sum, min_unit_size, alloc_size;
2267 int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */
2268 int last_allocs, group, unit;
2269 unsigned int cpu, tcpu;
2270 struct pcpu_alloc_info *ai;
2271 unsigned int *cpu_map;
2272
2273 /* this function may be called multiple times */
2274 memset(group_map, 0, sizeof(group_map));
2275 memset(group_cnt, 0, sizeof(group_cnt));
2276
2277 /* calculate size_sum and ensure dyn_size is enough for early alloc */
2278 size_sum = PFN_ALIGN(static_size + reserved_size +
2279 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2280 dyn_size = size_sum - static_size - reserved_size;
2281
2282 /*
2283 * Determine min_unit_size, alloc_size and max_upa such that
2284 * alloc_size is multiple of atom_size and is the smallest
2285 * which can accommodate 4k aligned segments which are equal to
2286 * or larger than min_unit_size.
2287 */
2288 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2289
2290 /* determine the maximum # of units that can fit in an allocation */
2291 alloc_size = roundup(min_unit_size, atom_size);
2292 upa = alloc_size / min_unit_size;
2293 while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2294 upa--;
2295 max_upa = upa;
2296
2297 /* group cpus according to their proximity */
2298 for_each_possible_cpu(cpu) {
2299 group = 0;
2300 next_group:
2301 for_each_possible_cpu(tcpu) {
2302 if (cpu == tcpu)
2303 break;
2304 if (group_map[tcpu] == group && cpu_distance_fn &&
2305 (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
2306 cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
2307 group++;
2308 nr_groups = max(nr_groups, group + 1);
2309 goto next_group;
2310 }
2311 }
2312 group_map[cpu] = group;
2313 group_cnt[group]++;
2314 }
2315
2316 /*
2317 * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2318 * Expand the unit_size until we use >= 75% of the units allocated.
2319 * Related to atom_size, which could be much larger than the unit_size.
2320 */
2321 last_allocs = INT_MAX;
2322 for (upa = max_upa; upa; upa--) {
2323 int allocs = 0, wasted = 0;
2324
2325 if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2326 continue;
2327
2328 for (group = 0; group < nr_groups; group++) {
2329 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2330 allocs += this_allocs;
2331 wasted += this_allocs * upa - group_cnt[group];
2332 }
2333
2334 /*
2335 * Don't accept if wastage is over 1/3. The
2336 * greater-than comparison ensures upa==1 always
2337 * passes the following check.
2338 */
2339 if (wasted > num_possible_cpus() / 3)
2340 continue;
2341
2342 /* and then don't consume more memory */
2343 if (allocs > last_allocs)
2344 break;
2345 last_allocs = allocs;
2346 best_upa = upa;
2347 }
2348 upa = best_upa;
2349
2350 /* allocate and fill alloc_info */
2351 for (group = 0; group < nr_groups; group++)
2352 nr_units += roundup(group_cnt[group], upa);
2353
2354 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2355 if (!ai)
2356 return ERR_PTR(-ENOMEM);
2357 cpu_map = ai->groups[0].cpu_map;
2358
2359 for (group = 0; group < nr_groups; group++) {
2360 ai->groups[group].cpu_map = cpu_map;
2361 cpu_map += roundup(group_cnt[group], upa);
2362 }
2363
2364 ai->static_size = static_size;
2365 ai->reserved_size = reserved_size;
2366 ai->dyn_size = dyn_size;
2367 ai->unit_size = alloc_size / upa;
2368 ai->atom_size = atom_size;
2369 ai->alloc_size = alloc_size;
2370
2371 for (group = 0, unit = 0; group_cnt[group]; group++) {
2372 struct pcpu_group_info *gi = &ai->groups[group];
2373
2374 /*
2375 * Initialize base_offset as if all groups are located
2376 * back-to-back. The caller should update this to
2377 * reflect actual allocation.
2378 */
2379 gi->base_offset = unit * ai->unit_size;
2380
2381 for_each_possible_cpu(cpu)
2382 if (group_map[cpu] == group)
2383 gi->cpu_map[gi->nr_units++] = cpu;
2384 gi->nr_units = roundup(gi->nr_units, upa);
2385 unit += gi->nr_units;
2386 }
2387 BUG_ON(unit != nr_units);
2388
2389 return ai;
2390}
2391#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
2392
2393#if defined(BUILD_EMBED_FIRST_CHUNK)
2394/**
2395 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
2396 * @reserved_size: the size of reserved percpu area in bytes
2397 * @dyn_size: minimum free size for dynamic allocation in bytes
2398 * @atom_size: allocation atom size
2399 * @cpu_distance_fn: callback to determine distance between cpus, optional
2400 * @alloc_fn: function to allocate percpu page
2401 * @free_fn: function to free percpu page
2402 *
2403 * This is a helper to ease setting up embedded first percpu chunk and
2404 * can be called where pcpu_setup_first_chunk() is expected.
2405 *
2406 * If this function is used to setup the first chunk, it is allocated
2407 * by calling @alloc_fn and used as-is without being mapped into
2408 * vmalloc area. Allocations are always whole multiples of @atom_size
2409 * aligned to @atom_size.
2410 *
2411 * This enables the first chunk to piggy back on the linear physical
2412 * mapping which often uses larger page size. Please note that this
2413 * can result in very sparse cpu->unit mapping on NUMA machines thus
2414 * requiring large vmalloc address space. Don't use this allocator if
2415 * vmalloc space is not orders of magnitude larger than distances
2416 * between node memory addresses (ie. 32bit NUMA machines).
2417 *
2418 * @dyn_size specifies the minimum dynamic area size.
2419 *
2420 * If the needed size is smaller than the minimum or specified unit
2421 * size, the leftover is returned using @free_fn.
2422 *
2423 * RETURNS:
2424 * 0 on success, -errno on failure.
2425 */
2426int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
2427 size_t atom_size,
2428 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
2429 pcpu_fc_alloc_fn_t alloc_fn,
2430 pcpu_fc_free_fn_t free_fn)
2431{
2432 void *base = (void *)ULONG_MAX;
2433 void **areas = NULL;
2434 struct pcpu_alloc_info *ai;
2435 size_t size_sum, areas_size;
2436 unsigned long max_distance;
2437 int group, i, highest_group, rc;
2438
2439 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
2440 cpu_distance_fn);
2441 if (IS_ERR(ai))
2442 return PTR_ERR(ai);
2443
2444 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2445 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
2446
2447 areas = memblock_virt_alloc_nopanic(areas_size, 0);
2448 if (!areas) {
2449 rc = -ENOMEM;
2450 goto out_free;
2451 }
2452
2453 /* allocate, copy and determine base address & max_distance */
2454 highest_group = 0;
2455 for (group = 0; group < ai->nr_groups; group++) {
2456 struct pcpu_group_info *gi = &ai->groups[group];
2457 unsigned int cpu = NR_CPUS;
2458 void *ptr;
2459
2460 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
2461 cpu = gi->cpu_map[i];
2462 BUG_ON(cpu == NR_CPUS);
2463
2464 /* allocate space for the whole group */
2465 ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
2466 if (!ptr) {
2467 rc = -ENOMEM;
2468 goto out_free_areas;
2469 }
2470 /* kmemleak tracks the percpu allocations separately */
2471 kmemleak_free(ptr);
2472 areas[group] = ptr;
2473
2474 base = min(ptr, base);
2475 if (ptr > areas[highest_group])
2476 highest_group = group;
2477 }
2478 max_distance = areas[highest_group] - base;
2479 max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
2480
2481 /* warn if maximum distance is further than 75% of vmalloc space */
2482 if (max_distance > VMALLOC_TOTAL * 3 / 4) {
2483 pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
2484 max_distance, VMALLOC_TOTAL);
2485#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2486 /* and fail if we have fallback */
2487 rc = -EINVAL;
2488 goto out_free_areas;
2489#endif
2490 }
2491
2492 /*
2493 * Copy data and free unused parts. This should happen after all
2494 * allocations are complete; otherwise, we may end up with
2495 * overlapping groups.
2496 */
2497 for (group = 0; group < ai->nr_groups; group++) {
2498 struct pcpu_group_info *gi = &ai->groups[group];
2499 void *ptr = areas[group];
2500
2501 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
2502 if (gi->cpu_map[i] == NR_CPUS) {
2503 /* unused unit, free whole */
2504 free_fn(ptr, ai->unit_size);
2505 continue;
2506 }
2507 /* copy and return the unused part */
2508 memcpy(ptr, __per_cpu_load, ai->static_size);
2509 free_fn(ptr + size_sum, ai->unit_size - size_sum);
2510 }
2511 }
2512
2513 /* base address is now known, determine group base offsets */
2514 for (group = 0; group < ai->nr_groups; group++) {
2515 ai->groups[group].base_offset = areas[group] - base;
2516 }
2517
2518 pr_info("Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
2519 PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,
2520 ai->dyn_size, ai->unit_size);
2521
2522 rc = pcpu_setup_first_chunk(ai, base);
2523 goto out_free;
2524
2525out_free_areas:
2526 for (group = 0; group < ai->nr_groups; group++)
2527 if (areas[group])
2528 free_fn(areas[group],
2529 ai->groups[group].nr_units * ai->unit_size);
2530out_free:
2531 pcpu_free_alloc_info(ai);
2532 if (areas)
2533 memblock_free_early(__pa(areas), areas_size);
2534 return rc;
2535}
2536#endif /* BUILD_EMBED_FIRST_CHUNK */
2537
2538#ifdef BUILD_PAGE_FIRST_CHUNK
2539/**
2540 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
2541 * @reserved_size: the size of reserved percpu area in bytes
2542 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
2543 * @free_fn: function to free percpu page, always called with PAGE_SIZE
2544 * @populate_pte_fn: function to populate pte
2545 *
2546 * This is a helper to ease setting up page-remapped first percpu
2547 * chunk and can be called where pcpu_setup_first_chunk() is expected.
2548 *
2549 * This is the basic allocator. Static percpu area is allocated
2550 * page-by-page into vmalloc area.
2551 *
2552 * RETURNS:
2553 * 0 on success, -errno on failure.
2554 */
2555int __init pcpu_page_first_chunk(size_t reserved_size,
2556 pcpu_fc_alloc_fn_t alloc_fn,
2557 pcpu_fc_free_fn_t free_fn,
2558 pcpu_fc_populate_pte_fn_t populate_pte_fn)
2559{
2560 static struct vm_struct vm;
2561 struct pcpu_alloc_info *ai;
2562 char psize_str[16];
2563 int unit_pages;
2564 size_t pages_size;
2565 struct page **pages;
2566 int unit, i, j, rc;
2567 int upa;
2568 int nr_g0_units;
2569
2570 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
2571
2572 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
2573 if (IS_ERR(ai))
2574 return PTR_ERR(ai);
2575 BUG_ON(ai->nr_groups != 1);
2576 upa = ai->alloc_size/ai->unit_size;
2577 nr_g0_units = roundup(num_possible_cpus(), upa);
2578 if (unlikely(WARN_ON(ai->groups[0].nr_units != nr_g0_units))) {
2579 pcpu_free_alloc_info(ai);
2580 return -EINVAL;
2581 }
2582
2583 unit_pages = ai->unit_size >> PAGE_SHIFT;
2584
2585 /* unaligned allocations can't be freed, round up to page size */
2586 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
2587 sizeof(pages[0]));
2588 pages = memblock_virt_alloc(pages_size, 0);
2589
2590 /* allocate pages */
2591 j = 0;
2592 for (unit = 0; unit < num_possible_cpus(); unit++) {
2593 unsigned int cpu = ai->groups[0].cpu_map[unit];
2594 for (i = 0; i < unit_pages; i++) {
2595 void *ptr;
2596
2597 ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
2598 if (!ptr) {
2599 pr_warn("failed to allocate %s page for cpu%u\n",
2600 psize_str, cpu);
2601 goto enomem;
2602 }
2603 /* kmemleak tracks the percpu allocations separately */
2604 kmemleak_free(ptr);
2605 pages[j++] = virt_to_page(ptr);
2606 }
2607 }
2608
2609 /* allocate vm area, map the pages and copy static data */
2610 vm.flags = VM_ALLOC;
2611 vm.size = num_possible_cpus() * ai->unit_size;
2612 vm_area_register_early(&vm, PAGE_SIZE);
2613
2614 for (unit = 0; unit < num_possible_cpus(); unit++) {
2615 unsigned long unit_addr =
2616 (unsigned long)vm.addr + unit * ai->unit_size;
2617
2618 for (i = 0; i < unit_pages; i++)
2619 populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
2620
2621 /* pte already populated, the following shouldn't fail */
2622 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
2623 unit_pages);
2624 if (rc < 0)
2625 panic("failed to map percpu area, err=%d\n", rc);
2626
2627 /*
2628 * FIXME: Archs with virtual cache should flush local
2629 * cache for the linear mapping here - something
2630 * equivalent to flush_cache_vmap() on the local cpu.
2631 * flush_cache_vmap() can't be used as most supporting
2632 * data structures are not set up yet.
2633 */
2634
2635 /* copy static data */
2636 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
2637 }
2638
2639 /* we're ready, commit */
2640 pr_info("%d %s pages/cpu @%p s%zu r%zu d%zu\n",
2641 unit_pages, psize_str, vm.addr, ai->static_size,
2642 ai->reserved_size, ai->dyn_size);
2643
2644 rc = pcpu_setup_first_chunk(ai, vm.addr);
2645 goto out_free_ar;
2646
2647enomem:
2648 while (--j >= 0)
2649 free_fn(page_address(pages[j]), PAGE_SIZE);
2650 rc = -ENOMEM;
2651out_free_ar:
2652 memblock_free_early(__pa(pages), pages_size);
2653 pcpu_free_alloc_info(ai);
2654 return rc;
2655}
2656#endif /* BUILD_PAGE_FIRST_CHUNK */
2657
2658#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
2659/*
2660 * Generic SMP percpu area setup.
2661 *
2662 * The embedding helper is used because its behavior closely resembles
2663 * the original non-dynamic generic percpu area setup. This is
2664 * important because many archs have addressing restrictions and might
2665 * fail if the percpu area is located far away from the previous
2666 * location. As an added bonus, in non-NUMA cases, embedding is
2667 * generally a good idea TLB-wise because percpu area can piggy back
2668 * on the physical linear memory mapping which uses large page
2669 * mappings on applicable archs.
2670 */
2671unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
2672EXPORT_SYMBOL(__per_cpu_offset);
2673
2674static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
2675 size_t align)
2676{
2677 return memblock_virt_alloc_from_nopanic(
2678 size, align, __pa(MAX_DMA_ADDRESS));
2679}
2680
2681static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
2682{
2683 memblock_free_early(__pa(ptr), size);
2684}
2685
2686void __init setup_per_cpu_areas(void)
2687{
2688 unsigned long delta;
2689 unsigned int cpu;
2690 int rc;
2691
2692 /*
2693 * Always reserve area for module percpu variables. That's
2694 * what the legacy allocator did.
2695 */
2696 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
2697 PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
2698 pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
2699 if (rc < 0)
2700 panic("Failed to initialize percpu areas.");
2701
2702 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
2703 for_each_possible_cpu(cpu)
2704 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
2705}
2706#endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
2707
2708#else /* CONFIG_SMP */
2709
2710/*
2711 * UP percpu area setup.
2712 *
2713 * UP always uses km-based percpu allocator with identity mapping.
2714 * Static percpu variables are indistinguishable from the usual static
2715 * variables and don't require any special preparation.
2716 */
2717void __init setup_per_cpu_areas(void)
2718{
2719 const size_t unit_size =
2720 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
2721 PERCPU_DYNAMIC_RESERVE));
2722 struct pcpu_alloc_info *ai;
2723 void *fc;
2724
2725 ai = pcpu_alloc_alloc_info(1, 1);
2726 fc = memblock_virt_alloc_from_nopanic(unit_size,
2727 PAGE_SIZE,
2728 __pa(MAX_DMA_ADDRESS));
2729 if (!ai || !fc)
2730 panic("Failed to allocate memory for percpu areas.");
2731 /* kmemleak tracks the percpu allocations separately */
2732 kmemleak_free(fc);
2733
2734 ai->dyn_size = unit_size;
2735 ai->unit_size = unit_size;
2736 ai->atom_size = unit_size;
2737 ai->alloc_size = unit_size;
2738 ai->groups[0].nr_units = 1;
2739 ai->groups[0].cpu_map[0] = 0;
2740
2741 if (pcpu_setup_first_chunk(ai, fc) < 0)
2742 panic("Failed to initialize percpu areas.");
2743 pcpu_free_alloc_info(ai);
2744}
2745
2746#endif /* CONFIG_SMP */
2747
2748/*
2749 * Percpu allocator is initialized early during boot when neither slab or
2750 * workqueue is available. Plug async management until everything is up
2751 * and running.
2752 */
2753static int __init percpu_enable_async(void)
2754{
2755 pcpu_async_enabled = true;
2756 return 0;
2757}
2758subsys_initcall(percpu_enable_async);