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