nfsd4: typo logical vs bitwise negate for want_mask
[linux-btrfs-devel.git] / mm / percpu.c
blobbf80e55dbed7e66fcd28f6dbc46c86fbd222a008
1 /*
2 * mm/percpu.c - percpu memory allocator
4 * Copyright (C) 2009 SUSE Linux Products GmbH
5 * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 * This file is released under the GPLv2.
9 * This is percpu allocator which can handle both static and dynamic
10 * areas. Percpu areas are allocated in chunks. Each chunk is
11 * consisted of boot-time determined number of units and the first
12 * chunk is used for static percpu variables in the kernel image
13 * (special boot time alloc/init handling necessary as these areas
14 * need to be brought up before allocation services are running).
15 * Unit grows as necessary and all units grow or shrink in unison.
16 * When a chunk is filled up, another chunk is allocated.
18 * c0 c1 c2
19 * ------------------- ------------------- ------------
20 * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
21 * ------------------- ...... ------------------- .... ------------
23 * Allocation is done in offset-size areas of single unit space. Ie,
24 * an area of 512 bytes at 6k in c1 occupies 512 bytes at 6k of c1:u0,
25 * c1:u1, c1:u2 and c1:u3. On UMA, units corresponds directly to
26 * cpus. On NUMA, the mapping can be non-linear and even sparse.
27 * Percpu access can be done by configuring percpu base registers
28 * according to cpu to unit mapping and pcpu_unit_size.
30 * There are usually many small percpu allocations many of them being
31 * as small as 4 bytes. The allocator organizes chunks into lists
32 * according to free size and tries to allocate from the fullest one.
33 * Each chunk keeps the maximum contiguous area size hint which is
34 * guaranteed to be equal to or larger than the maximum contiguous
35 * area in the chunk. This helps the allocator not to iterate the
36 * chunk maps unnecessarily.
38 * Allocation state in each chunk is kept using an array of integers
39 * on chunk->map. A positive value in the map represents a free
40 * region and negative allocated. Allocation inside a chunk is done
41 * by scanning this map sequentially and serving the first matching
42 * entry. This is mostly copied from the percpu_modalloc() allocator.
43 * Chunks can be determined from the address using the index field
44 * in the page struct. The index field contains a pointer to the chunk.
46 * To use this allocator, arch code should do the followings.
48 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
49 * regular address to percpu pointer and back if they need to be
50 * different from the default
52 * - use pcpu_setup_first_chunk() during percpu area initialization to
53 * setup the first chunk containing the kernel static percpu area
56 #include <linux/bitmap.h>
57 #include <linux/bootmem.h>
58 #include <linux/err.h>
59 #include <linux/list.h>
60 #include <linux/log2.h>
61 #include <linux/mm.h>
62 #include <linux/module.h>
63 #include <linux/mutex.h>
64 #include <linux/percpu.h>
65 #include <linux/pfn.h>
66 #include <linux/slab.h>
67 #include <linux/spinlock.h>
68 #include <linux/vmalloc.h>
69 #include <linux/workqueue.h>
71 #include <asm/cacheflush.h>
72 #include <asm/sections.h>
73 #include <asm/tlbflush.h>
74 #include <asm/io.h>
76 #define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */
77 #define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */
79 #ifdef CONFIG_SMP
80 /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
81 #ifndef __addr_to_pcpu_ptr
82 #define __addr_to_pcpu_ptr(addr) \
83 (void __percpu *)((unsigned long)(addr) - \
84 (unsigned long)pcpu_base_addr + \
85 (unsigned long)__per_cpu_start)
86 #endif
87 #ifndef __pcpu_ptr_to_addr
88 #define __pcpu_ptr_to_addr(ptr) \
89 (void __force *)((unsigned long)(ptr) + \
90 (unsigned long)pcpu_base_addr - \
91 (unsigned long)__per_cpu_start)
92 #endif
93 #else /* CONFIG_SMP */
94 /* on UP, it's always identity mapped */
95 #define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
96 #define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
97 #endif /* CONFIG_SMP */
99 struct pcpu_chunk {
100 struct list_head list; /* linked to pcpu_slot lists */
101 int free_size; /* free bytes in the chunk */
102 int contig_hint; /* max contiguous size hint */
103 void *base_addr; /* base address of this chunk */
104 int map_used; /* # of map entries used */
105 int map_alloc; /* # of map entries allocated */
106 int *map; /* allocation map */
107 void *data; /* chunk data */
108 bool immutable; /* no [de]population allowed */
109 unsigned long populated[]; /* populated bitmap */
112 static int pcpu_unit_pages __read_mostly;
113 static int pcpu_unit_size __read_mostly;
114 static int pcpu_nr_units __read_mostly;
115 static int pcpu_atom_size __read_mostly;
116 static int pcpu_nr_slots __read_mostly;
117 static size_t pcpu_chunk_struct_size __read_mostly;
119 /* cpus with the lowest and highest unit numbers */
120 static unsigned int pcpu_first_unit_cpu __read_mostly;
121 static unsigned int pcpu_last_unit_cpu __read_mostly;
123 /* the address of the first chunk which starts with the kernel static area */
124 void *pcpu_base_addr __read_mostly;
125 EXPORT_SYMBOL_GPL(pcpu_base_addr);
127 static const int *pcpu_unit_map __read_mostly; /* cpu -> unit */
128 const unsigned long *pcpu_unit_offsets __read_mostly; /* cpu -> unit offset */
130 /* group information, used for vm allocation */
131 static int pcpu_nr_groups __read_mostly;
132 static const unsigned long *pcpu_group_offsets __read_mostly;
133 static const size_t *pcpu_group_sizes __read_mostly;
136 * The first chunk which always exists. Note that unlike other
137 * chunks, this one can be allocated and mapped in several different
138 * ways and thus often doesn't live in the vmalloc area.
140 static struct pcpu_chunk *pcpu_first_chunk;
143 * Optional reserved chunk. This chunk reserves part of the first
144 * chunk and serves it for reserved allocations. The amount of
145 * reserved offset is in pcpu_reserved_chunk_limit. When reserved
146 * area doesn't exist, the following variables contain NULL and 0
147 * respectively.
149 static struct pcpu_chunk *pcpu_reserved_chunk;
150 static int pcpu_reserved_chunk_limit;
153 * Synchronization rules.
155 * There are two locks - pcpu_alloc_mutex and pcpu_lock. The former
156 * protects allocation/reclaim paths, chunks, populated bitmap and
157 * vmalloc mapping. The latter is a spinlock and protects the index
158 * data structures - chunk slots, chunks and area maps in chunks.
160 * During allocation, pcpu_alloc_mutex is kept locked all the time and
161 * pcpu_lock is grabbed and released as necessary. All actual memory
162 * allocations are done using GFP_KERNEL with pcpu_lock released. In
163 * general, percpu memory can't be allocated with irq off but
164 * irqsave/restore are still used in alloc path so that it can be used
165 * from early init path - sched_init() specifically.
167 * Free path accesses and alters only the index data structures, so it
168 * can be safely called from atomic context. When memory needs to be
169 * returned to the system, free path schedules reclaim_work which
170 * grabs both pcpu_alloc_mutex and pcpu_lock, unlinks chunks to be
171 * reclaimed, release both locks and frees the chunks. Note that it's
172 * necessary to grab both locks to remove a chunk from circulation as
173 * allocation path might be referencing the chunk with only
174 * pcpu_alloc_mutex locked.
176 static DEFINE_MUTEX(pcpu_alloc_mutex); /* protects whole alloc and reclaim */
177 static DEFINE_SPINLOCK(pcpu_lock); /* protects index data structures */
179 static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */
181 /* reclaim work to release fully free chunks, scheduled from free path */
182 static void pcpu_reclaim(struct work_struct *work);
183 static DECLARE_WORK(pcpu_reclaim_work, pcpu_reclaim);
185 static bool pcpu_addr_in_first_chunk(void *addr)
187 void *first_start = pcpu_first_chunk->base_addr;
189 return addr >= first_start && addr < first_start + pcpu_unit_size;
192 static bool pcpu_addr_in_reserved_chunk(void *addr)
194 void *first_start = pcpu_first_chunk->base_addr;
196 return addr >= first_start &&
197 addr < first_start + pcpu_reserved_chunk_limit;
200 static int __pcpu_size_to_slot(int size)
202 int highbit = fls(size); /* size is in bytes */
203 return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
206 static int pcpu_size_to_slot(int size)
208 if (size == pcpu_unit_size)
209 return pcpu_nr_slots - 1;
210 return __pcpu_size_to_slot(size);
213 static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
215 if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int))
216 return 0;
218 return pcpu_size_to_slot(chunk->free_size);
221 /* set the pointer to a chunk in a page struct */
222 static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
224 page->index = (unsigned long)pcpu;
227 /* obtain pointer to a chunk from a page struct */
228 static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
230 return (struct pcpu_chunk *)page->index;
233 static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
235 return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
238 static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
239 unsigned int cpu, int page_idx)
241 return (unsigned long)chunk->base_addr + pcpu_unit_offsets[cpu] +
242 (page_idx << PAGE_SHIFT);
245 static void __maybe_unused pcpu_next_unpop(struct pcpu_chunk *chunk,
246 int *rs, int *re, int end)
248 *rs = find_next_zero_bit(chunk->populated, end, *rs);
249 *re = find_next_bit(chunk->populated, end, *rs + 1);
252 static void __maybe_unused pcpu_next_pop(struct pcpu_chunk *chunk,
253 int *rs, int *re, int end)
255 *rs = find_next_bit(chunk->populated, end, *rs);
256 *re = find_next_zero_bit(chunk->populated, end, *rs + 1);
260 * (Un)populated page region iterators. Iterate over (un)populated
261 * page regions between @start and @end in @chunk. @rs and @re should
262 * be integer variables and will be set to start and end page index of
263 * the current region.
265 #define pcpu_for_each_unpop_region(chunk, rs, re, start, end) \
266 for ((rs) = (start), pcpu_next_unpop((chunk), &(rs), &(re), (end)); \
267 (rs) < (re); \
268 (rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end)))
270 #define pcpu_for_each_pop_region(chunk, rs, re, start, end) \
271 for ((rs) = (start), pcpu_next_pop((chunk), &(rs), &(re), (end)); \
272 (rs) < (re); \
273 (rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end)))
276 * pcpu_mem_alloc - allocate memory
277 * @size: bytes to allocate
279 * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
280 * kzalloc() is used; otherwise, vmalloc() is used. The returned
281 * memory is always zeroed.
283 * CONTEXT:
284 * Does GFP_KERNEL allocation.
286 * RETURNS:
287 * Pointer to the allocated area on success, NULL on failure.
289 static void *pcpu_mem_alloc(size_t size)
291 if (WARN_ON_ONCE(!slab_is_available()))
292 return NULL;
294 if (size <= PAGE_SIZE)
295 return kzalloc(size, GFP_KERNEL);
296 else
297 return vzalloc(size);
301 * pcpu_mem_free - free memory
302 * @ptr: memory to free
303 * @size: size of the area
305 * Free @ptr. @ptr should have been allocated using pcpu_mem_alloc().
307 static void pcpu_mem_free(void *ptr, size_t size)
309 if (size <= PAGE_SIZE)
310 kfree(ptr);
311 else
312 vfree(ptr);
316 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
317 * @chunk: chunk of interest
318 * @oslot: the previous slot it was on
320 * This function is called after an allocation or free changed @chunk.
321 * New slot according to the changed state is determined and @chunk is
322 * moved to the slot. Note that the reserved chunk is never put on
323 * chunk slots.
325 * CONTEXT:
326 * pcpu_lock.
328 static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
330 int nslot = pcpu_chunk_slot(chunk);
332 if (chunk != pcpu_reserved_chunk && oslot != nslot) {
333 if (oslot < nslot)
334 list_move(&chunk->list, &pcpu_slot[nslot]);
335 else
336 list_move_tail(&chunk->list, &pcpu_slot[nslot]);
341 * pcpu_need_to_extend - determine whether chunk area map needs to be extended
342 * @chunk: chunk of interest
344 * Determine whether area map of @chunk needs to be extended to
345 * accommodate a new allocation.
347 * CONTEXT:
348 * pcpu_lock.
350 * RETURNS:
351 * New target map allocation length if extension is necessary, 0
352 * otherwise.
354 static int pcpu_need_to_extend(struct pcpu_chunk *chunk)
356 int new_alloc;
358 if (chunk->map_alloc >= chunk->map_used + 2)
359 return 0;
361 new_alloc = PCPU_DFL_MAP_ALLOC;
362 while (new_alloc < chunk->map_used + 2)
363 new_alloc *= 2;
365 return new_alloc;
369 * pcpu_extend_area_map - extend area map of a chunk
370 * @chunk: chunk of interest
371 * @new_alloc: new target allocation length of the area map
373 * Extend area map of @chunk to have @new_alloc entries.
375 * CONTEXT:
376 * Does GFP_KERNEL allocation. Grabs and releases pcpu_lock.
378 * RETURNS:
379 * 0 on success, -errno on failure.
381 static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
383 int *old = NULL, *new = NULL;
384 size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
385 unsigned long flags;
387 new = pcpu_mem_alloc(new_size);
388 if (!new)
389 return -ENOMEM;
391 /* acquire pcpu_lock and switch to new area map */
392 spin_lock_irqsave(&pcpu_lock, flags);
394 if (new_alloc <= chunk->map_alloc)
395 goto out_unlock;
397 old_size = chunk->map_alloc * sizeof(chunk->map[0]);
398 old = chunk->map;
400 memcpy(new, old, old_size);
402 chunk->map_alloc = new_alloc;
403 chunk->map = new;
404 new = NULL;
406 out_unlock:
407 spin_unlock_irqrestore(&pcpu_lock, flags);
410 * pcpu_mem_free() might end up calling vfree() which uses
411 * IRQ-unsafe lock and thus can't be called under pcpu_lock.
413 pcpu_mem_free(old, old_size);
414 pcpu_mem_free(new, new_size);
416 return 0;
420 * pcpu_split_block - split a map block
421 * @chunk: chunk of interest
422 * @i: index of map block to split
423 * @head: head size in bytes (can be 0)
424 * @tail: tail size in bytes (can be 0)
426 * Split the @i'th map block into two or three blocks. If @head is
427 * non-zero, @head bytes block is inserted before block @i moving it
428 * to @i+1 and reducing its size by @head bytes.
430 * If @tail is non-zero, the target block, which can be @i or @i+1
431 * depending on @head, is reduced by @tail bytes and @tail byte block
432 * is inserted after the target block.
434 * @chunk->map must have enough free slots to accommodate the split.
436 * CONTEXT:
437 * pcpu_lock.
439 static void pcpu_split_block(struct pcpu_chunk *chunk, int i,
440 int head, int tail)
442 int nr_extra = !!head + !!tail;
444 BUG_ON(chunk->map_alloc < chunk->map_used + nr_extra);
446 /* insert new subblocks */
447 memmove(&chunk->map[i + nr_extra], &chunk->map[i],
448 sizeof(chunk->map[0]) * (chunk->map_used - i));
449 chunk->map_used += nr_extra;
451 if (head) {
452 chunk->map[i + 1] = chunk->map[i] - head;
453 chunk->map[i++] = head;
455 if (tail) {
456 chunk->map[i++] -= tail;
457 chunk->map[i] = tail;
462 * pcpu_alloc_area - allocate area from a pcpu_chunk
463 * @chunk: chunk of interest
464 * @size: wanted size in bytes
465 * @align: wanted align
467 * Try to allocate @size bytes area aligned at @align from @chunk.
468 * Note that this function only allocates the offset. It doesn't
469 * populate or map the area.
471 * @chunk->map must have at least two free slots.
473 * CONTEXT:
474 * pcpu_lock.
476 * RETURNS:
477 * Allocated offset in @chunk on success, -1 if no matching area is
478 * found.
480 static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
482 int oslot = pcpu_chunk_slot(chunk);
483 int max_contig = 0;
484 int i, off;
486 for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) {
487 bool is_last = i + 1 == chunk->map_used;
488 int head, tail;
490 /* extra for alignment requirement */
491 head = ALIGN(off, align) - off;
492 BUG_ON(i == 0 && head != 0);
494 if (chunk->map[i] < 0)
495 continue;
496 if (chunk->map[i] < head + size) {
497 max_contig = max(chunk->map[i], max_contig);
498 continue;
502 * If head is small or the previous block is free,
503 * merge'em. Note that 'small' is defined as smaller
504 * than sizeof(int), which is very small but isn't too
505 * uncommon for percpu allocations.
507 if (head && (head < sizeof(int) || chunk->map[i - 1] > 0)) {
508 if (chunk->map[i - 1] > 0)
509 chunk->map[i - 1] += head;
510 else {
511 chunk->map[i - 1] -= head;
512 chunk->free_size -= head;
514 chunk->map[i] -= head;
515 off += head;
516 head = 0;
519 /* if tail is small, just keep it around */
520 tail = chunk->map[i] - head - size;
521 if (tail < sizeof(int))
522 tail = 0;
524 /* split if warranted */
525 if (head || tail) {
526 pcpu_split_block(chunk, i, head, tail);
527 if (head) {
528 i++;
529 off += head;
530 max_contig = max(chunk->map[i - 1], max_contig);
532 if (tail)
533 max_contig = max(chunk->map[i + 1], max_contig);
536 /* update hint and mark allocated */
537 if (is_last)
538 chunk->contig_hint = max_contig; /* fully scanned */
539 else
540 chunk->contig_hint = max(chunk->contig_hint,
541 max_contig);
543 chunk->free_size -= chunk->map[i];
544 chunk->map[i] = -chunk->map[i];
546 pcpu_chunk_relocate(chunk, oslot);
547 return off;
550 chunk->contig_hint = max_contig; /* fully scanned */
551 pcpu_chunk_relocate(chunk, oslot);
553 /* tell the upper layer that this chunk has no matching area */
554 return -1;
558 * pcpu_free_area - free area to a pcpu_chunk
559 * @chunk: chunk of interest
560 * @freeme: offset of area to free
562 * Free area starting from @freeme to @chunk. Note that this function
563 * only modifies the allocation map. It doesn't depopulate or unmap
564 * the area.
566 * CONTEXT:
567 * pcpu_lock.
569 static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme)
571 int oslot = pcpu_chunk_slot(chunk);
572 int i, off;
574 for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++]))
575 if (off == freeme)
576 break;
577 BUG_ON(off != freeme);
578 BUG_ON(chunk->map[i] > 0);
580 chunk->map[i] = -chunk->map[i];
581 chunk->free_size += chunk->map[i];
583 /* merge with previous? */
584 if (i > 0 && chunk->map[i - 1] >= 0) {
585 chunk->map[i - 1] += chunk->map[i];
586 chunk->map_used--;
587 memmove(&chunk->map[i], &chunk->map[i + 1],
588 (chunk->map_used - i) * sizeof(chunk->map[0]));
589 i--;
591 /* merge with next? */
592 if (i + 1 < chunk->map_used && chunk->map[i + 1] >= 0) {
593 chunk->map[i] += chunk->map[i + 1];
594 chunk->map_used--;
595 memmove(&chunk->map[i + 1], &chunk->map[i + 2],
596 (chunk->map_used - (i + 1)) * sizeof(chunk->map[0]));
599 chunk->contig_hint = max(chunk->map[i], chunk->contig_hint);
600 pcpu_chunk_relocate(chunk, oslot);
603 static struct pcpu_chunk *pcpu_alloc_chunk(void)
605 struct pcpu_chunk *chunk;
607 chunk = pcpu_mem_alloc(pcpu_chunk_struct_size);
608 if (!chunk)
609 return NULL;
611 chunk->map = pcpu_mem_alloc(PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0]));
612 if (!chunk->map) {
613 kfree(chunk);
614 return NULL;
617 chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
618 chunk->map[chunk->map_used++] = pcpu_unit_size;
620 INIT_LIST_HEAD(&chunk->list);
621 chunk->free_size = pcpu_unit_size;
622 chunk->contig_hint = pcpu_unit_size;
624 return chunk;
627 static void pcpu_free_chunk(struct pcpu_chunk *chunk)
629 if (!chunk)
630 return;
631 pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]));
632 kfree(chunk);
636 * Chunk management implementation.
638 * To allow different implementations, chunk alloc/free and
639 * [de]population are implemented in a separate file which is pulled
640 * into this file and compiled together. The following functions
641 * should be implemented.
643 * pcpu_populate_chunk - populate the specified range of a chunk
644 * pcpu_depopulate_chunk - depopulate the specified range of a chunk
645 * pcpu_create_chunk - create a new chunk
646 * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
647 * pcpu_addr_to_page - translate address to physical address
648 * pcpu_verify_alloc_info - check alloc_info is acceptable during init
650 static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size);
651 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size);
652 static struct pcpu_chunk *pcpu_create_chunk(void);
653 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
654 static struct page *pcpu_addr_to_page(void *addr);
655 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
657 #ifdef CONFIG_NEED_PER_CPU_KM
658 #include "percpu-km.c"
659 #else
660 #include "percpu-vm.c"
661 #endif
664 * pcpu_chunk_addr_search - determine chunk containing specified address
665 * @addr: address for which the chunk needs to be determined.
667 * RETURNS:
668 * The address of the found chunk.
670 static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
672 /* is it in the first chunk? */
673 if (pcpu_addr_in_first_chunk(addr)) {
674 /* is it in the reserved area? */
675 if (pcpu_addr_in_reserved_chunk(addr))
676 return pcpu_reserved_chunk;
677 return pcpu_first_chunk;
681 * The address is relative to unit0 which might be unused and
682 * thus unmapped. Offset the address to the unit space of the
683 * current processor before looking it up in the vmalloc
684 * space. Note that any possible cpu id can be used here, so
685 * there's no need to worry about preemption or cpu hotplug.
687 addr += pcpu_unit_offsets[raw_smp_processor_id()];
688 return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
692 * pcpu_alloc - the percpu allocator
693 * @size: size of area to allocate in bytes
694 * @align: alignment of area (max PAGE_SIZE)
695 * @reserved: allocate from the reserved chunk if available
697 * Allocate percpu area of @size bytes aligned at @align.
699 * CONTEXT:
700 * Does GFP_KERNEL allocation.
702 * RETURNS:
703 * Percpu pointer to the allocated area on success, NULL on failure.
705 static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
707 static int warn_limit = 10;
708 struct pcpu_chunk *chunk;
709 const char *err;
710 int slot, off, new_alloc;
711 unsigned long flags;
713 if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
714 WARN(true, "illegal size (%zu) or align (%zu) for "
715 "percpu allocation\n", size, align);
716 return NULL;
719 mutex_lock(&pcpu_alloc_mutex);
720 spin_lock_irqsave(&pcpu_lock, flags);
722 /* serve reserved allocations from the reserved chunk if available */
723 if (reserved && pcpu_reserved_chunk) {
724 chunk = pcpu_reserved_chunk;
726 if (size > chunk->contig_hint) {
727 err = "alloc from reserved chunk failed";
728 goto fail_unlock;
731 while ((new_alloc = pcpu_need_to_extend(chunk))) {
732 spin_unlock_irqrestore(&pcpu_lock, flags);
733 if (pcpu_extend_area_map(chunk, new_alloc) < 0) {
734 err = "failed to extend area map of reserved chunk";
735 goto fail_unlock_mutex;
737 spin_lock_irqsave(&pcpu_lock, flags);
740 off = pcpu_alloc_area(chunk, size, align);
741 if (off >= 0)
742 goto area_found;
744 err = "alloc from reserved chunk failed";
745 goto fail_unlock;
748 restart:
749 /* search through normal chunks */
750 for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
751 list_for_each_entry(chunk, &pcpu_slot[slot], list) {
752 if (size > chunk->contig_hint)
753 continue;
755 new_alloc = pcpu_need_to_extend(chunk);
756 if (new_alloc) {
757 spin_unlock_irqrestore(&pcpu_lock, flags);
758 if (pcpu_extend_area_map(chunk,
759 new_alloc) < 0) {
760 err = "failed to extend area map";
761 goto fail_unlock_mutex;
763 spin_lock_irqsave(&pcpu_lock, flags);
765 * pcpu_lock has been dropped, need to
766 * restart cpu_slot list walking.
768 goto restart;
771 off = pcpu_alloc_area(chunk, size, align);
772 if (off >= 0)
773 goto area_found;
777 /* hmmm... no space left, create a new chunk */
778 spin_unlock_irqrestore(&pcpu_lock, flags);
780 chunk = pcpu_create_chunk();
781 if (!chunk) {
782 err = "failed to allocate new chunk";
783 goto fail_unlock_mutex;
786 spin_lock_irqsave(&pcpu_lock, flags);
787 pcpu_chunk_relocate(chunk, -1);
788 goto restart;
790 area_found:
791 spin_unlock_irqrestore(&pcpu_lock, flags);
793 /* populate, map and clear the area */
794 if (pcpu_populate_chunk(chunk, off, size)) {
795 spin_lock_irqsave(&pcpu_lock, flags);
796 pcpu_free_area(chunk, off);
797 err = "failed to populate";
798 goto fail_unlock;
801 mutex_unlock(&pcpu_alloc_mutex);
803 /* return address relative to base address */
804 return __addr_to_pcpu_ptr(chunk->base_addr + off);
806 fail_unlock:
807 spin_unlock_irqrestore(&pcpu_lock, flags);
808 fail_unlock_mutex:
809 mutex_unlock(&pcpu_alloc_mutex);
810 if (warn_limit) {
811 pr_warning("PERCPU: allocation failed, size=%zu align=%zu, "
812 "%s\n", size, align, err);
813 dump_stack();
814 if (!--warn_limit)
815 pr_info("PERCPU: limit reached, disable warning\n");
817 return NULL;
821 * __alloc_percpu - allocate dynamic percpu area
822 * @size: size of area to allocate in bytes
823 * @align: alignment of area (max PAGE_SIZE)
825 * Allocate zero-filled percpu area of @size bytes aligned at @align.
826 * Might sleep. Might trigger writeouts.
828 * CONTEXT:
829 * Does GFP_KERNEL allocation.
831 * RETURNS:
832 * Percpu pointer to the allocated area on success, NULL on failure.
834 void __percpu *__alloc_percpu(size_t size, size_t align)
836 return pcpu_alloc(size, align, false);
838 EXPORT_SYMBOL_GPL(__alloc_percpu);
841 * __alloc_reserved_percpu - allocate reserved percpu area
842 * @size: size of area to allocate in bytes
843 * @align: alignment of area (max PAGE_SIZE)
845 * Allocate zero-filled percpu area of @size bytes aligned at @align
846 * from reserved percpu area if arch has set it up; otherwise,
847 * allocation is served from the same dynamic area. Might sleep.
848 * Might trigger writeouts.
850 * CONTEXT:
851 * Does GFP_KERNEL allocation.
853 * RETURNS:
854 * Percpu pointer to the allocated area on success, NULL on failure.
856 void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
858 return pcpu_alloc(size, align, true);
862 * pcpu_reclaim - reclaim fully free chunks, workqueue function
863 * @work: unused
865 * Reclaim all fully free chunks except for the first one.
867 * CONTEXT:
868 * workqueue context.
870 static void pcpu_reclaim(struct work_struct *work)
872 LIST_HEAD(todo);
873 struct list_head *head = &pcpu_slot[pcpu_nr_slots - 1];
874 struct pcpu_chunk *chunk, *next;
876 mutex_lock(&pcpu_alloc_mutex);
877 spin_lock_irq(&pcpu_lock);
879 list_for_each_entry_safe(chunk, next, head, list) {
880 WARN_ON(chunk->immutable);
882 /* spare the first one */
883 if (chunk == list_first_entry(head, struct pcpu_chunk, list))
884 continue;
886 list_move(&chunk->list, &todo);
889 spin_unlock_irq(&pcpu_lock);
891 list_for_each_entry_safe(chunk, next, &todo, list) {
892 pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size);
893 pcpu_destroy_chunk(chunk);
896 mutex_unlock(&pcpu_alloc_mutex);
900 * free_percpu - free percpu area
901 * @ptr: pointer to area to free
903 * Free percpu area @ptr.
905 * CONTEXT:
906 * Can be called from atomic context.
908 void free_percpu(void __percpu *ptr)
910 void *addr;
911 struct pcpu_chunk *chunk;
912 unsigned long flags;
913 int off;
915 if (!ptr)
916 return;
918 addr = __pcpu_ptr_to_addr(ptr);
920 spin_lock_irqsave(&pcpu_lock, flags);
922 chunk = pcpu_chunk_addr_search(addr);
923 off = addr - chunk->base_addr;
925 pcpu_free_area(chunk, off);
927 /* if there are more than one fully free chunks, wake up grim reaper */
928 if (chunk->free_size == pcpu_unit_size) {
929 struct pcpu_chunk *pos;
931 list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
932 if (pos != chunk) {
933 schedule_work(&pcpu_reclaim_work);
934 break;
938 spin_unlock_irqrestore(&pcpu_lock, flags);
940 EXPORT_SYMBOL_GPL(free_percpu);
943 * is_kernel_percpu_address - test whether address is from static percpu area
944 * @addr: address to test
946 * Test whether @addr belongs to in-kernel static percpu area. Module
947 * static percpu areas are not considered. For those, use
948 * is_module_percpu_address().
950 * RETURNS:
951 * %true if @addr is from in-kernel static percpu area, %false otherwise.
953 bool is_kernel_percpu_address(unsigned long addr)
955 #ifdef CONFIG_SMP
956 const size_t static_size = __per_cpu_end - __per_cpu_start;
957 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
958 unsigned int cpu;
960 for_each_possible_cpu(cpu) {
961 void *start = per_cpu_ptr(base, cpu);
963 if ((void *)addr >= start && (void *)addr < start + static_size)
964 return true;
966 #endif
967 /* on UP, can't distinguish from other static vars, always false */
968 return false;
972 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
973 * @addr: the address to be converted to physical address
975 * Given @addr which is dereferenceable address obtained via one of
976 * percpu access macros, this function translates it into its physical
977 * address. The caller is responsible for ensuring @addr stays valid
978 * until this function finishes.
980 * RETURNS:
981 * The physical address for @addr.
983 phys_addr_t per_cpu_ptr_to_phys(void *addr)
985 void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
986 bool in_first_chunk = false;
987 unsigned long first_start, first_end;
988 unsigned int cpu;
991 * The following test on first_start/end isn't strictly
992 * necessary but will speed up lookups of addresses which
993 * aren't in the first chunk.
995 first_start = pcpu_chunk_addr(pcpu_first_chunk, pcpu_first_unit_cpu, 0);
996 first_end = pcpu_chunk_addr(pcpu_first_chunk, pcpu_last_unit_cpu,
997 pcpu_unit_pages);
998 if ((unsigned long)addr >= first_start &&
999 (unsigned long)addr < first_end) {
1000 for_each_possible_cpu(cpu) {
1001 void *start = per_cpu_ptr(base, cpu);
1003 if (addr >= start && addr < start + pcpu_unit_size) {
1004 in_first_chunk = true;
1005 break;
1010 if (in_first_chunk) {
1011 if (!is_vmalloc_addr(addr))
1012 return __pa(addr);
1013 else
1014 return page_to_phys(vmalloc_to_page(addr));
1015 } else
1016 return page_to_phys(pcpu_addr_to_page(addr));
1020 * pcpu_alloc_alloc_info - allocate percpu allocation info
1021 * @nr_groups: the number of groups
1022 * @nr_units: the number of units
1024 * Allocate ai which is large enough for @nr_groups groups containing
1025 * @nr_units units. The returned ai's groups[0].cpu_map points to the
1026 * cpu_map array which is long enough for @nr_units and filled with
1027 * NR_CPUS. It's the caller's responsibility to initialize cpu_map
1028 * pointer of other groups.
1030 * RETURNS:
1031 * Pointer to the allocated pcpu_alloc_info on success, NULL on
1032 * failure.
1034 struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
1035 int nr_units)
1037 struct pcpu_alloc_info *ai;
1038 size_t base_size, ai_size;
1039 void *ptr;
1040 int unit;
1042 base_size = ALIGN(sizeof(*ai) + nr_groups * sizeof(ai->groups[0]),
1043 __alignof__(ai->groups[0].cpu_map[0]));
1044 ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
1046 ptr = alloc_bootmem_nopanic(PFN_ALIGN(ai_size));
1047 if (!ptr)
1048 return NULL;
1049 ai = ptr;
1050 ptr += base_size;
1052 ai->groups[0].cpu_map = ptr;
1054 for (unit = 0; unit < nr_units; unit++)
1055 ai->groups[0].cpu_map[unit] = NR_CPUS;
1057 ai->nr_groups = nr_groups;
1058 ai->__ai_size = PFN_ALIGN(ai_size);
1060 return ai;
1064 * pcpu_free_alloc_info - free percpu allocation info
1065 * @ai: pcpu_alloc_info to free
1067 * Free @ai which was allocated by pcpu_alloc_alloc_info().
1069 void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
1071 free_bootmem(__pa(ai), ai->__ai_size);
1075 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
1076 * @lvl: loglevel
1077 * @ai: allocation info to dump
1079 * Print out information about @ai using loglevel @lvl.
1081 static void pcpu_dump_alloc_info(const char *lvl,
1082 const struct pcpu_alloc_info *ai)
1084 int group_width = 1, cpu_width = 1, width;
1085 char empty_str[] = "--------";
1086 int alloc = 0, alloc_end = 0;
1087 int group, v;
1088 int upa, apl; /* units per alloc, allocs per line */
1090 v = ai->nr_groups;
1091 while (v /= 10)
1092 group_width++;
1094 v = num_possible_cpus();
1095 while (v /= 10)
1096 cpu_width++;
1097 empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
1099 upa = ai->alloc_size / ai->unit_size;
1100 width = upa * (cpu_width + 1) + group_width + 3;
1101 apl = rounddown_pow_of_two(max(60 / width, 1));
1103 printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
1104 lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
1105 ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
1107 for (group = 0; group < ai->nr_groups; group++) {
1108 const struct pcpu_group_info *gi = &ai->groups[group];
1109 int unit = 0, unit_end = 0;
1111 BUG_ON(gi->nr_units % upa);
1112 for (alloc_end += gi->nr_units / upa;
1113 alloc < alloc_end; alloc++) {
1114 if (!(alloc % apl)) {
1115 printk("\n");
1116 printk("%spcpu-alloc: ", lvl);
1118 printk("[%0*d] ", group_width, group);
1120 for (unit_end += upa; unit < unit_end; unit++)
1121 if (gi->cpu_map[unit] != NR_CPUS)
1122 printk("%0*d ", cpu_width,
1123 gi->cpu_map[unit]);
1124 else
1125 printk("%s ", empty_str);
1128 printk("\n");
1132 * pcpu_setup_first_chunk - initialize the first percpu chunk
1133 * @ai: pcpu_alloc_info describing how to percpu area is shaped
1134 * @base_addr: mapped address
1136 * Initialize the first percpu chunk which contains the kernel static
1137 * perpcu area. This function is to be called from arch percpu area
1138 * setup path.
1140 * @ai contains all information necessary to initialize the first
1141 * chunk and prime the dynamic percpu allocator.
1143 * @ai->static_size is the size of static percpu area.
1145 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
1146 * reserve after the static area in the first chunk. This reserves
1147 * the first chunk such that it's available only through reserved
1148 * percpu allocation. This is primarily used to serve module percpu
1149 * static areas on architectures where the addressing model has
1150 * limited offset range for symbol relocations to guarantee module
1151 * percpu symbols fall inside the relocatable range.
1153 * @ai->dyn_size determines the number of bytes available for dynamic
1154 * allocation in the first chunk. The area between @ai->static_size +
1155 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
1157 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
1158 * and equal to or larger than @ai->static_size + @ai->reserved_size +
1159 * @ai->dyn_size.
1161 * @ai->atom_size is the allocation atom size and used as alignment
1162 * for vm areas.
1164 * @ai->alloc_size is the allocation size and always multiple of
1165 * @ai->atom_size. This is larger than @ai->atom_size if
1166 * @ai->unit_size is larger than @ai->atom_size.
1168 * @ai->nr_groups and @ai->groups describe virtual memory layout of
1169 * percpu areas. Units which should be colocated are put into the
1170 * same group. Dynamic VM areas will be allocated according to these
1171 * groupings. If @ai->nr_groups is zero, a single group containing
1172 * all units is assumed.
1174 * The caller should have mapped the first chunk at @base_addr and
1175 * copied static data to each unit.
1177 * If the first chunk ends up with both reserved and dynamic areas, it
1178 * is served by two chunks - one to serve the core static and reserved
1179 * areas and the other for the dynamic area. They share the same vm
1180 * and page map but uses different area allocation map to stay away
1181 * from each other. The latter chunk is circulated in the chunk slots
1182 * and available for dynamic allocation like any other chunks.
1184 * RETURNS:
1185 * 0 on success, -errno on failure.
1187 int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
1188 void *base_addr)
1190 static char cpus_buf[4096] __initdata;
1191 static int smap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1192 static int dmap[PERCPU_DYNAMIC_EARLY_SLOTS] __initdata;
1193 size_t dyn_size = ai->dyn_size;
1194 size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
1195 struct pcpu_chunk *schunk, *dchunk = NULL;
1196 unsigned long *group_offsets;
1197 size_t *group_sizes;
1198 unsigned long *unit_off;
1199 unsigned int cpu;
1200 int *unit_map;
1201 int group, unit, i;
1203 cpumask_scnprintf(cpus_buf, sizeof(cpus_buf), cpu_possible_mask);
1205 #define PCPU_SETUP_BUG_ON(cond) do { \
1206 if (unlikely(cond)) { \
1207 pr_emerg("PERCPU: failed to initialize, %s", #cond); \
1208 pr_emerg("PERCPU: cpu_possible_mask=%s\n", cpus_buf); \
1209 pcpu_dump_alloc_info(KERN_EMERG, ai); \
1210 BUG(); \
1212 } while (0)
1214 /* sanity checks */
1215 PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
1216 #ifdef CONFIG_SMP
1217 PCPU_SETUP_BUG_ON(!ai->static_size);
1218 PCPU_SETUP_BUG_ON((unsigned long)__per_cpu_start & ~PAGE_MASK);
1219 #endif
1220 PCPU_SETUP_BUG_ON(!base_addr);
1221 PCPU_SETUP_BUG_ON((unsigned long)base_addr & ~PAGE_MASK);
1222 PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
1223 PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
1224 PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
1225 PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
1226 PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
1228 /* process group information and build config tables accordingly */
1229 group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
1230 group_sizes = alloc_bootmem(ai->nr_groups * sizeof(group_sizes[0]));
1231 unit_map = alloc_bootmem(nr_cpu_ids * sizeof(unit_map[0]));
1232 unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
1234 for (cpu = 0; cpu < nr_cpu_ids; cpu++)
1235 unit_map[cpu] = UINT_MAX;
1236 pcpu_first_unit_cpu = NR_CPUS;
1238 for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
1239 const struct pcpu_group_info *gi = &ai->groups[group];
1241 group_offsets[group] = gi->base_offset;
1242 group_sizes[group] = gi->nr_units * ai->unit_size;
1244 for (i = 0; i < gi->nr_units; i++) {
1245 cpu = gi->cpu_map[i];
1246 if (cpu == NR_CPUS)
1247 continue;
1249 PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
1250 PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
1251 PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
1253 unit_map[cpu] = unit + i;
1254 unit_off[cpu] = gi->base_offset + i * ai->unit_size;
1256 if (pcpu_first_unit_cpu == NR_CPUS)
1257 pcpu_first_unit_cpu = cpu;
1258 pcpu_last_unit_cpu = cpu;
1261 pcpu_nr_units = unit;
1263 for_each_possible_cpu(cpu)
1264 PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
1266 /* we're done parsing the input, undefine BUG macro and dump config */
1267 #undef PCPU_SETUP_BUG_ON
1268 pcpu_dump_alloc_info(KERN_DEBUG, ai);
1270 pcpu_nr_groups = ai->nr_groups;
1271 pcpu_group_offsets = group_offsets;
1272 pcpu_group_sizes = group_sizes;
1273 pcpu_unit_map = unit_map;
1274 pcpu_unit_offsets = unit_off;
1276 /* determine basic parameters */
1277 pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
1278 pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
1279 pcpu_atom_size = ai->atom_size;
1280 pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
1281 BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
1284 * Allocate chunk slots. The additional last slot is for
1285 * empty chunks.
1287 pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
1288 pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0]));
1289 for (i = 0; i < pcpu_nr_slots; i++)
1290 INIT_LIST_HEAD(&pcpu_slot[i]);
1293 * Initialize static chunk. If reserved_size is zero, the
1294 * static chunk covers static area + dynamic allocation area
1295 * in the first chunk. If reserved_size is not zero, it
1296 * covers static area + reserved area (mostly used for module
1297 * static percpu allocation).
1299 schunk = alloc_bootmem(pcpu_chunk_struct_size);
1300 INIT_LIST_HEAD(&schunk->list);
1301 schunk->base_addr = base_addr;
1302 schunk->map = smap;
1303 schunk->map_alloc = ARRAY_SIZE(smap);
1304 schunk->immutable = true;
1305 bitmap_fill(schunk->populated, pcpu_unit_pages);
1307 if (ai->reserved_size) {
1308 schunk->free_size = ai->reserved_size;
1309 pcpu_reserved_chunk = schunk;
1310 pcpu_reserved_chunk_limit = ai->static_size + ai->reserved_size;
1311 } else {
1312 schunk->free_size = dyn_size;
1313 dyn_size = 0; /* dynamic area covered */
1315 schunk->contig_hint = schunk->free_size;
1317 schunk->map[schunk->map_used++] = -ai->static_size;
1318 if (schunk->free_size)
1319 schunk->map[schunk->map_used++] = schunk->free_size;
1321 /* init dynamic chunk if necessary */
1322 if (dyn_size) {
1323 dchunk = alloc_bootmem(pcpu_chunk_struct_size);
1324 INIT_LIST_HEAD(&dchunk->list);
1325 dchunk->base_addr = base_addr;
1326 dchunk->map = dmap;
1327 dchunk->map_alloc = ARRAY_SIZE(dmap);
1328 dchunk->immutable = true;
1329 bitmap_fill(dchunk->populated, pcpu_unit_pages);
1331 dchunk->contig_hint = dchunk->free_size = dyn_size;
1332 dchunk->map[dchunk->map_used++] = -pcpu_reserved_chunk_limit;
1333 dchunk->map[dchunk->map_used++] = dchunk->free_size;
1336 /* link the first chunk in */
1337 pcpu_first_chunk = dchunk ?: schunk;
1338 pcpu_chunk_relocate(pcpu_first_chunk, -1);
1340 /* we're done */
1341 pcpu_base_addr = base_addr;
1342 return 0;
1345 #ifdef CONFIG_SMP
1347 const char *pcpu_fc_names[PCPU_FC_NR] __initdata = {
1348 [PCPU_FC_AUTO] = "auto",
1349 [PCPU_FC_EMBED] = "embed",
1350 [PCPU_FC_PAGE] = "page",
1353 enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
1355 static int __init percpu_alloc_setup(char *str)
1357 if (0)
1358 /* nada */;
1359 #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
1360 else if (!strcmp(str, "embed"))
1361 pcpu_chosen_fc = PCPU_FC_EMBED;
1362 #endif
1363 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1364 else if (!strcmp(str, "page"))
1365 pcpu_chosen_fc = PCPU_FC_PAGE;
1366 #endif
1367 else
1368 pr_warning("PERCPU: unknown allocator %s specified\n", str);
1370 return 0;
1372 early_param("percpu_alloc", percpu_alloc_setup);
1375 * pcpu_embed_first_chunk() is used by the generic percpu setup.
1376 * Build it if needed by the arch config or the generic setup is going
1377 * to be used.
1379 #if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
1380 !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
1381 #define BUILD_EMBED_FIRST_CHUNK
1382 #endif
1384 /* build pcpu_page_first_chunk() iff needed by the arch config */
1385 #if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
1386 #define BUILD_PAGE_FIRST_CHUNK
1387 #endif
1389 /* pcpu_build_alloc_info() is used by both embed and page first chunk */
1390 #if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
1392 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
1393 * @reserved_size: the size of reserved percpu area in bytes
1394 * @dyn_size: minimum free size for dynamic allocation in bytes
1395 * @atom_size: allocation atom size
1396 * @cpu_distance_fn: callback to determine distance between cpus, optional
1398 * This function determines grouping of units, their mappings to cpus
1399 * and other parameters considering needed percpu size, allocation
1400 * atom size and distances between CPUs.
1402 * Groups are always mutliples of atom size and CPUs which are of
1403 * LOCAL_DISTANCE both ways are grouped together and share space for
1404 * units in the same group. The returned configuration is guaranteed
1405 * to have CPUs on different nodes on different groups and >=75% usage
1406 * of allocated virtual address space.
1408 * RETURNS:
1409 * On success, pointer to the new allocation_info is returned. On
1410 * failure, ERR_PTR value is returned.
1412 static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
1413 size_t reserved_size, size_t dyn_size,
1414 size_t atom_size,
1415 pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
1417 static int group_map[NR_CPUS] __initdata;
1418 static int group_cnt[NR_CPUS] __initdata;
1419 const size_t static_size = __per_cpu_end - __per_cpu_start;
1420 int nr_groups = 1, nr_units = 0;
1421 size_t size_sum, min_unit_size, alloc_size;
1422 int upa, max_upa, uninitialized_var(best_upa); /* units_per_alloc */
1423 int last_allocs, group, unit;
1424 unsigned int cpu, tcpu;
1425 struct pcpu_alloc_info *ai;
1426 unsigned int *cpu_map;
1428 /* this function may be called multiple times */
1429 memset(group_map, 0, sizeof(group_map));
1430 memset(group_cnt, 0, sizeof(group_cnt));
1432 /* calculate size_sum and ensure dyn_size is enough for early alloc */
1433 size_sum = PFN_ALIGN(static_size + reserved_size +
1434 max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
1435 dyn_size = size_sum - static_size - reserved_size;
1438 * Determine min_unit_size, alloc_size and max_upa such that
1439 * alloc_size is multiple of atom_size and is the smallest
1440 * which can accommodate 4k aligned segments which are equal to
1441 * or larger than min_unit_size.
1443 min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
1445 alloc_size = roundup(min_unit_size, atom_size);
1446 upa = alloc_size / min_unit_size;
1447 while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1448 upa--;
1449 max_upa = upa;
1451 /* group cpus according to their proximity */
1452 for_each_possible_cpu(cpu) {
1453 group = 0;
1454 next_group:
1455 for_each_possible_cpu(tcpu) {
1456 if (cpu == tcpu)
1457 break;
1458 if (group_map[tcpu] == group && cpu_distance_fn &&
1459 (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
1460 cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
1461 group++;
1462 nr_groups = max(nr_groups, group + 1);
1463 goto next_group;
1466 group_map[cpu] = group;
1467 group_cnt[group]++;
1471 * Expand unit size until address space usage goes over 75%
1472 * and then as much as possible without using more address
1473 * space.
1475 last_allocs = INT_MAX;
1476 for (upa = max_upa; upa; upa--) {
1477 int allocs = 0, wasted = 0;
1479 if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
1480 continue;
1482 for (group = 0; group < nr_groups; group++) {
1483 int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
1484 allocs += this_allocs;
1485 wasted += this_allocs * upa - group_cnt[group];
1489 * Don't accept if wastage is over 1/3. The
1490 * greater-than comparison ensures upa==1 always
1491 * passes the following check.
1493 if (wasted > num_possible_cpus() / 3)
1494 continue;
1496 /* and then don't consume more memory */
1497 if (allocs > last_allocs)
1498 break;
1499 last_allocs = allocs;
1500 best_upa = upa;
1502 upa = best_upa;
1504 /* allocate and fill alloc_info */
1505 for (group = 0; group < nr_groups; group++)
1506 nr_units += roundup(group_cnt[group], upa);
1508 ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
1509 if (!ai)
1510 return ERR_PTR(-ENOMEM);
1511 cpu_map = ai->groups[0].cpu_map;
1513 for (group = 0; group < nr_groups; group++) {
1514 ai->groups[group].cpu_map = cpu_map;
1515 cpu_map += roundup(group_cnt[group], upa);
1518 ai->static_size = static_size;
1519 ai->reserved_size = reserved_size;
1520 ai->dyn_size = dyn_size;
1521 ai->unit_size = alloc_size / upa;
1522 ai->atom_size = atom_size;
1523 ai->alloc_size = alloc_size;
1525 for (group = 0, unit = 0; group_cnt[group]; group++) {
1526 struct pcpu_group_info *gi = &ai->groups[group];
1529 * Initialize base_offset as if all groups are located
1530 * back-to-back. The caller should update this to
1531 * reflect actual allocation.
1533 gi->base_offset = unit * ai->unit_size;
1535 for_each_possible_cpu(cpu)
1536 if (group_map[cpu] == group)
1537 gi->cpu_map[gi->nr_units++] = cpu;
1538 gi->nr_units = roundup(gi->nr_units, upa);
1539 unit += gi->nr_units;
1541 BUG_ON(unit != nr_units);
1543 return ai;
1545 #endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
1547 #if defined(BUILD_EMBED_FIRST_CHUNK)
1549 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
1550 * @reserved_size: the size of reserved percpu area in bytes
1551 * @dyn_size: minimum free size for dynamic allocation in bytes
1552 * @atom_size: allocation atom size
1553 * @cpu_distance_fn: callback to determine distance between cpus, optional
1554 * @alloc_fn: function to allocate percpu page
1555 * @free_fn: function to free percpu page
1557 * This is a helper to ease setting up embedded first percpu chunk and
1558 * can be called where pcpu_setup_first_chunk() is expected.
1560 * If this function is used to setup the first chunk, it is allocated
1561 * by calling @alloc_fn and used as-is without being mapped into
1562 * vmalloc area. Allocations are always whole multiples of @atom_size
1563 * aligned to @atom_size.
1565 * This enables the first chunk to piggy back on the linear physical
1566 * mapping which often uses larger page size. Please note that this
1567 * can result in very sparse cpu->unit mapping on NUMA machines thus
1568 * requiring large vmalloc address space. Don't use this allocator if
1569 * vmalloc space is not orders of magnitude larger than distances
1570 * between node memory addresses (ie. 32bit NUMA machines).
1572 * @dyn_size specifies the minimum dynamic area size.
1574 * If the needed size is smaller than the minimum or specified unit
1575 * size, the leftover is returned using @free_fn.
1577 * RETURNS:
1578 * 0 on success, -errno on failure.
1580 int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
1581 size_t atom_size,
1582 pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
1583 pcpu_fc_alloc_fn_t alloc_fn,
1584 pcpu_fc_free_fn_t free_fn)
1586 void *base = (void *)ULONG_MAX;
1587 void **areas = NULL;
1588 struct pcpu_alloc_info *ai;
1589 size_t size_sum, areas_size, max_distance;
1590 int group, i, rc;
1592 ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
1593 cpu_distance_fn);
1594 if (IS_ERR(ai))
1595 return PTR_ERR(ai);
1597 size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
1598 areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
1600 areas = alloc_bootmem_nopanic(areas_size);
1601 if (!areas) {
1602 rc = -ENOMEM;
1603 goto out_free;
1606 /* allocate, copy and determine base address */
1607 for (group = 0; group < ai->nr_groups; group++) {
1608 struct pcpu_group_info *gi = &ai->groups[group];
1609 unsigned int cpu = NR_CPUS;
1610 void *ptr;
1612 for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
1613 cpu = gi->cpu_map[i];
1614 BUG_ON(cpu == NR_CPUS);
1616 /* allocate space for the whole group */
1617 ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
1618 if (!ptr) {
1619 rc = -ENOMEM;
1620 goto out_free_areas;
1622 areas[group] = ptr;
1624 base = min(ptr, base);
1626 for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
1627 if (gi->cpu_map[i] == NR_CPUS) {
1628 /* unused unit, free whole */
1629 free_fn(ptr, ai->unit_size);
1630 continue;
1632 /* copy and return the unused part */
1633 memcpy(ptr, __per_cpu_load, ai->static_size);
1634 free_fn(ptr + size_sum, ai->unit_size - size_sum);
1638 /* base address is now known, determine group base offsets */
1639 max_distance = 0;
1640 for (group = 0; group < ai->nr_groups; group++) {
1641 ai->groups[group].base_offset = areas[group] - base;
1642 max_distance = max_t(size_t, max_distance,
1643 ai->groups[group].base_offset);
1645 max_distance += ai->unit_size;
1647 /* warn if maximum distance is further than 75% of vmalloc space */
1648 if (max_distance > (VMALLOC_END - VMALLOC_START) * 3 / 4) {
1649 pr_warning("PERCPU: max_distance=0x%zx too large for vmalloc "
1650 "space 0x%lx\n", max_distance,
1651 (unsigned long)(VMALLOC_END - VMALLOC_START));
1652 #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
1653 /* and fail if we have fallback */
1654 rc = -EINVAL;
1655 goto out_free;
1656 #endif
1659 pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
1660 PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,
1661 ai->dyn_size, ai->unit_size);
1663 rc = pcpu_setup_first_chunk(ai, base);
1664 goto out_free;
1666 out_free_areas:
1667 for (group = 0; group < ai->nr_groups; group++)
1668 free_fn(areas[group],
1669 ai->groups[group].nr_units * ai->unit_size);
1670 out_free:
1671 pcpu_free_alloc_info(ai);
1672 if (areas)
1673 free_bootmem(__pa(areas), areas_size);
1674 return rc;
1676 #endif /* BUILD_EMBED_FIRST_CHUNK */
1678 #ifdef BUILD_PAGE_FIRST_CHUNK
1680 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
1681 * @reserved_size: the size of reserved percpu area in bytes
1682 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
1683 * @free_fn: function to free percpu page, always called with PAGE_SIZE
1684 * @populate_pte_fn: function to populate pte
1686 * This is a helper to ease setting up page-remapped first percpu
1687 * chunk and can be called where pcpu_setup_first_chunk() is expected.
1689 * This is the basic allocator. Static percpu area is allocated
1690 * page-by-page into vmalloc area.
1692 * RETURNS:
1693 * 0 on success, -errno on failure.
1695 int __init pcpu_page_first_chunk(size_t reserved_size,
1696 pcpu_fc_alloc_fn_t alloc_fn,
1697 pcpu_fc_free_fn_t free_fn,
1698 pcpu_fc_populate_pte_fn_t populate_pte_fn)
1700 static struct vm_struct vm;
1701 struct pcpu_alloc_info *ai;
1702 char psize_str[16];
1703 int unit_pages;
1704 size_t pages_size;
1705 struct page **pages;
1706 int unit, i, j, rc;
1708 snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
1710 ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
1711 if (IS_ERR(ai))
1712 return PTR_ERR(ai);
1713 BUG_ON(ai->nr_groups != 1);
1714 BUG_ON(ai->groups[0].nr_units != num_possible_cpus());
1716 unit_pages = ai->unit_size >> PAGE_SHIFT;
1718 /* unaligned allocations can't be freed, round up to page size */
1719 pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
1720 sizeof(pages[0]));
1721 pages = alloc_bootmem(pages_size);
1723 /* allocate pages */
1724 j = 0;
1725 for (unit = 0; unit < num_possible_cpus(); unit++)
1726 for (i = 0; i < unit_pages; i++) {
1727 unsigned int cpu = ai->groups[0].cpu_map[unit];
1728 void *ptr;
1730 ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
1731 if (!ptr) {
1732 pr_warning("PERCPU: failed to allocate %s page "
1733 "for cpu%u\n", psize_str, cpu);
1734 goto enomem;
1736 pages[j++] = virt_to_page(ptr);
1739 /* allocate vm area, map the pages and copy static data */
1740 vm.flags = VM_ALLOC;
1741 vm.size = num_possible_cpus() * ai->unit_size;
1742 vm_area_register_early(&vm, PAGE_SIZE);
1744 for (unit = 0; unit < num_possible_cpus(); unit++) {
1745 unsigned long unit_addr =
1746 (unsigned long)vm.addr + unit * ai->unit_size;
1748 for (i = 0; i < unit_pages; i++)
1749 populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
1751 /* pte already populated, the following shouldn't fail */
1752 rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
1753 unit_pages);
1754 if (rc < 0)
1755 panic("failed to map percpu area, err=%d\n", rc);
1758 * FIXME: Archs with virtual cache should flush local
1759 * cache for the linear mapping here - something
1760 * equivalent to flush_cache_vmap() on the local cpu.
1761 * flush_cache_vmap() can't be used as most supporting
1762 * data structures are not set up yet.
1765 /* copy static data */
1766 memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
1769 /* we're ready, commit */
1770 pr_info("PERCPU: %d %s pages/cpu @%p s%zu r%zu d%zu\n",
1771 unit_pages, psize_str, vm.addr, ai->static_size,
1772 ai->reserved_size, ai->dyn_size);
1774 rc = pcpu_setup_first_chunk(ai, vm.addr);
1775 goto out_free_ar;
1777 enomem:
1778 while (--j >= 0)
1779 free_fn(page_address(pages[j]), PAGE_SIZE);
1780 rc = -ENOMEM;
1781 out_free_ar:
1782 free_bootmem(__pa(pages), pages_size);
1783 pcpu_free_alloc_info(ai);
1784 return rc;
1786 #endif /* BUILD_PAGE_FIRST_CHUNK */
1788 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
1790 * Generic SMP percpu area setup.
1792 * The embedding helper is used because its behavior closely resembles
1793 * the original non-dynamic generic percpu area setup. This is
1794 * important because many archs have addressing restrictions and might
1795 * fail if the percpu area is located far away from the previous
1796 * location. As an added bonus, in non-NUMA cases, embedding is
1797 * generally a good idea TLB-wise because percpu area can piggy back
1798 * on the physical linear memory mapping which uses large page
1799 * mappings on applicable archs.
1801 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
1802 EXPORT_SYMBOL(__per_cpu_offset);
1804 static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
1805 size_t align)
1807 return __alloc_bootmem_nopanic(size, align, __pa(MAX_DMA_ADDRESS));
1810 static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
1812 free_bootmem(__pa(ptr), size);
1815 void __init setup_per_cpu_areas(void)
1817 unsigned long delta;
1818 unsigned int cpu;
1819 int rc;
1822 * Always reserve area for module percpu variables. That's
1823 * what the legacy allocator did.
1825 rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
1826 PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
1827 pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
1828 if (rc < 0)
1829 panic("Failed to initialize percpu areas.");
1831 delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
1832 for_each_possible_cpu(cpu)
1833 __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
1835 #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
1837 #else /* CONFIG_SMP */
1840 * UP percpu area setup.
1842 * UP always uses km-based percpu allocator with identity mapping.
1843 * Static percpu variables are indistinguishable from the usual static
1844 * variables and don't require any special preparation.
1846 void __init setup_per_cpu_areas(void)
1848 const size_t unit_size =
1849 roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
1850 PERCPU_DYNAMIC_RESERVE));
1851 struct pcpu_alloc_info *ai;
1852 void *fc;
1854 ai = pcpu_alloc_alloc_info(1, 1);
1855 fc = __alloc_bootmem(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
1856 if (!ai || !fc)
1857 panic("Failed to allocate memory for percpu areas.");
1859 ai->dyn_size = unit_size;
1860 ai->unit_size = unit_size;
1861 ai->atom_size = unit_size;
1862 ai->alloc_size = unit_size;
1863 ai->groups[0].nr_units = 1;
1864 ai->groups[0].cpu_map[0] = 0;
1866 if (pcpu_setup_first_chunk(ai, fc) < 0)
1867 panic("Failed to initialize percpu areas.");
1870 #endif /* CONFIG_SMP */
1873 * First and reserved chunks are initialized with temporary allocation
1874 * map in initdata so that they can be used before slab is online.
1875 * This function is called after slab is brought up and replaces those
1876 * with properly allocated maps.
1878 void __init percpu_init_late(void)
1880 struct pcpu_chunk *target_chunks[] =
1881 { pcpu_first_chunk, pcpu_reserved_chunk, NULL };
1882 struct pcpu_chunk *chunk;
1883 unsigned long flags;
1884 int i;
1886 for (i = 0; (chunk = target_chunks[i]); i++) {
1887 int *map;
1888 const size_t size = PERCPU_DYNAMIC_EARLY_SLOTS * sizeof(map[0]);
1890 BUILD_BUG_ON(size > PAGE_SIZE);
1892 map = pcpu_mem_alloc(size);
1893 BUG_ON(!map);
1895 spin_lock_irqsave(&pcpu_lock, flags);
1896 memcpy(map, chunk->map, size);
1897 chunk->map = map;
1898 spin_unlock_irqrestore(&pcpu_lock, flags);