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fbf59bc9 TH |
1 | /* |
2 | * linux/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 | * This file is released under the GPLv2. | |
8 | * | |
9 | * This is percpu allocator which can handle both static and dynamic | |
10 | * areas. Percpu areas are allocated in chunks in vmalloc area. Each | |
11 | * chunk is consisted of num_possible_cpus() units and the first chunk | |
12 | * is used for static percpu variables in the kernel image (special | |
13 | * boot time alloc/init handling necessary as these areas need to be | |
14 | * brought up before allocation services are running). Unit grows as | |
15 | * necessary and all units grow or shrink in unison. When a chunk is | |
16 | * filled up, another chunk is allocated. ie. in vmalloc area | |
17 | * | |
18 | * c0 c1 c2 | |
19 | * ------------------- ------------------- ------------ | |
20 | * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u | |
21 | * ------------------- ...... ------------------- .... ------------ | |
22 | * | |
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. Percpu access can be done by configuring | |
26 | * percpu base registers UNIT_SIZE apart. | |
27 | * | |
28 | * There are usually many small percpu allocations many of them as | |
29 | * small as 4 bytes. The allocator organizes chunks into lists | |
30 | * according to free size and tries to allocate from the fullest one. | |
31 | * Each chunk keeps the maximum contiguous area size hint which is | |
32 | * guaranteed to be eqaul to or larger than the maximum contiguous | |
33 | * area in the chunk. This helps the allocator not to iterate the | |
34 | * chunk maps unnecessarily. | |
35 | * | |
36 | * Allocation state in each chunk is kept using an array of integers | |
37 | * on chunk->map. A positive value in the map represents a free | |
38 | * region and negative allocated. Allocation inside a chunk is done | |
39 | * by scanning this map sequentially and serving the first matching | |
40 | * entry. This is mostly copied from the percpu_modalloc() allocator. | |
41 | * Chunks are also linked into a rb tree to ease address to chunk | |
42 | * mapping during free. | |
43 | * | |
44 | * To use this allocator, arch code should do the followings. | |
45 | * | |
46 | * - define CONFIG_HAVE_DYNAMIC_PER_CPU_AREA | |
47 | * | |
48 | * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate | |
49 | * regular address to percpu pointer and back | |
50 | * | |
8d408b4b TH |
51 | * - use pcpu_setup_first_chunk() during percpu area initialization to |
52 | * setup the first chunk containing the kernel static percpu area | |
fbf59bc9 TH |
53 | */ |
54 | ||
55 | #include <linux/bitmap.h> | |
56 | #include <linux/bootmem.h> | |
57 | #include <linux/list.h> | |
58 | #include <linux/mm.h> | |
59 | #include <linux/module.h> | |
60 | #include <linux/mutex.h> | |
61 | #include <linux/percpu.h> | |
62 | #include <linux/pfn.h> | |
63 | #include <linux/rbtree.h> | |
64 | #include <linux/slab.h> | |
65 | #include <linux/vmalloc.h> | |
66 | ||
67 | #include <asm/cacheflush.h> | |
68 | #include <asm/tlbflush.h> | |
69 | ||
fbf59bc9 TH |
70 | #define PCPU_SLOT_BASE_SHIFT 5 /* 1-31 shares the same slot */ |
71 | #define PCPU_DFL_MAP_ALLOC 16 /* start a map with 16 ents */ | |
72 | ||
73 | struct pcpu_chunk { | |
74 | struct list_head list; /* linked to pcpu_slot lists */ | |
75 | struct rb_node rb_node; /* key is chunk->vm->addr */ | |
76 | int free_size; /* free bytes in the chunk */ | |
77 | int contig_hint; /* max contiguous size hint */ | |
78 | struct vm_struct *vm; /* mapped vmalloc region */ | |
79 | int map_used; /* # of map entries used */ | |
80 | int map_alloc; /* # of map entries allocated */ | |
81 | int *map; /* allocation map */ | |
8d408b4b | 82 | bool immutable; /* no [de]population allowed */ |
fbf59bc9 TH |
83 | struct page *page[]; /* #cpus * UNIT_PAGES */ |
84 | }; | |
85 | ||
40150d37 TH |
86 | static int pcpu_unit_pages __read_mostly; |
87 | static int pcpu_unit_size __read_mostly; | |
88 | static int pcpu_chunk_size __read_mostly; | |
89 | static int pcpu_nr_slots __read_mostly; | |
90 | static size_t pcpu_chunk_struct_size __read_mostly; | |
fbf59bc9 TH |
91 | |
92 | /* the address of the first chunk which starts with the kernel static area */ | |
40150d37 | 93 | void *pcpu_base_addr __read_mostly; |
fbf59bc9 TH |
94 | EXPORT_SYMBOL_GPL(pcpu_base_addr); |
95 | ||
96 | /* the size of kernel static area */ | |
40150d37 | 97 | static int pcpu_static_size __read_mostly; |
fbf59bc9 TH |
98 | |
99 | /* | |
100 | * One mutex to rule them all. | |
101 | * | |
102 | * The following mutex is grabbed in the outermost public alloc/free | |
103 | * interface functions and released only when the operation is | |
104 | * complete. As such, every function in this file other than the | |
105 | * outermost functions are called under pcpu_mutex. | |
106 | * | |
107 | * It can easily be switched to use spinlock such that only the area | |
108 | * allocation and page population commit are protected with it doing | |
109 | * actual [de]allocation without holding any lock. However, given | |
110 | * what this allocator does, I think it's better to let them run | |
111 | * sequentially. | |
112 | */ | |
113 | static DEFINE_MUTEX(pcpu_mutex); | |
114 | ||
40150d37 | 115 | static struct list_head *pcpu_slot __read_mostly; /* chunk list slots */ |
fbf59bc9 TH |
116 | static struct rb_root pcpu_addr_root = RB_ROOT; /* chunks by address */ |
117 | ||
d9b55eeb | 118 | static int __pcpu_size_to_slot(int size) |
fbf59bc9 | 119 | { |
cae3aeb8 | 120 | int highbit = fls(size); /* size is in bytes */ |
fbf59bc9 TH |
121 | return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1); |
122 | } | |
123 | ||
d9b55eeb TH |
124 | static int pcpu_size_to_slot(int size) |
125 | { | |
126 | if (size == pcpu_unit_size) | |
127 | return pcpu_nr_slots - 1; | |
128 | return __pcpu_size_to_slot(size); | |
129 | } | |
130 | ||
fbf59bc9 TH |
131 | static int pcpu_chunk_slot(const struct pcpu_chunk *chunk) |
132 | { | |
133 | if (chunk->free_size < sizeof(int) || chunk->contig_hint < sizeof(int)) | |
134 | return 0; | |
135 | ||
136 | return pcpu_size_to_slot(chunk->free_size); | |
137 | } | |
138 | ||
139 | static int pcpu_page_idx(unsigned int cpu, int page_idx) | |
140 | { | |
d9b55eeb | 141 | return cpu * pcpu_unit_pages + page_idx; |
fbf59bc9 TH |
142 | } |
143 | ||
144 | static struct page **pcpu_chunk_pagep(struct pcpu_chunk *chunk, | |
145 | unsigned int cpu, int page_idx) | |
146 | { | |
147 | return &chunk->page[pcpu_page_idx(cpu, page_idx)]; | |
148 | } | |
149 | ||
150 | static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk, | |
151 | unsigned int cpu, int page_idx) | |
152 | { | |
153 | return (unsigned long)chunk->vm->addr + | |
154 | (pcpu_page_idx(cpu, page_idx) << PAGE_SHIFT); | |
155 | } | |
156 | ||
157 | static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk, | |
158 | int page_idx) | |
159 | { | |
160 | return *pcpu_chunk_pagep(chunk, 0, page_idx) != NULL; | |
161 | } | |
162 | ||
163 | /** | |
164 | * pcpu_realloc - versatile realloc | |
165 | * @p: the current pointer (can be NULL for new allocations) | |
cae3aeb8 TH |
166 | * @size: the current size in bytes (can be 0 for new allocations) |
167 | * @new_size: the wanted new size in bytes (can be 0 for free) | |
fbf59bc9 TH |
168 | * |
169 | * More robust realloc which can be used to allocate, resize or free a | |
170 | * memory area of arbitrary size. If the needed size goes over | |
171 | * PAGE_SIZE, kernel VM is used. | |
172 | * | |
173 | * RETURNS: | |
174 | * The new pointer on success, NULL on failure. | |
175 | */ | |
176 | static void *pcpu_realloc(void *p, size_t size, size_t new_size) | |
177 | { | |
178 | void *new; | |
179 | ||
180 | if (new_size <= PAGE_SIZE) | |
181 | new = kmalloc(new_size, GFP_KERNEL); | |
182 | else | |
183 | new = vmalloc(new_size); | |
184 | if (new_size && !new) | |
185 | return NULL; | |
186 | ||
187 | memcpy(new, p, min(size, new_size)); | |
188 | if (new_size > size) | |
189 | memset(new + size, 0, new_size - size); | |
190 | ||
191 | if (size <= PAGE_SIZE) | |
192 | kfree(p); | |
193 | else | |
194 | vfree(p); | |
195 | ||
196 | return new; | |
197 | } | |
198 | ||
199 | /** | |
200 | * pcpu_chunk_relocate - put chunk in the appropriate chunk slot | |
201 | * @chunk: chunk of interest | |
202 | * @oslot: the previous slot it was on | |
203 | * | |
204 | * This function is called after an allocation or free changed @chunk. | |
205 | * New slot according to the changed state is determined and @chunk is | |
206 | * moved to the slot. | |
207 | */ | |
208 | static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot) | |
209 | { | |
210 | int nslot = pcpu_chunk_slot(chunk); | |
211 | ||
212 | if (oslot != nslot) { | |
213 | if (oslot < nslot) | |
214 | list_move(&chunk->list, &pcpu_slot[nslot]); | |
215 | else | |
216 | list_move_tail(&chunk->list, &pcpu_slot[nslot]); | |
217 | } | |
218 | } | |
219 | ||
220 | static struct rb_node **pcpu_chunk_rb_search(void *addr, | |
221 | struct rb_node **parentp) | |
222 | { | |
223 | struct rb_node **p = &pcpu_addr_root.rb_node; | |
224 | struct rb_node *parent = NULL; | |
225 | struct pcpu_chunk *chunk; | |
226 | ||
227 | while (*p) { | |
228 | parent = *p; | |
229 | chunk = rb_entry(parent, struct pcpu_chunk, rb_node); | |
230 | ||
231 | if (addr < chunk->vm->addr) | |
232 | p = &(*p)->rb_left; | |
233 | else if (addr > chunk->vm->addr) | |
234 | p = &(*p)->rb_right; | |
235 | else | |
236 | break; | |
237 | } | |
238 | ||
239 | if (parentp) | |
240 | *parentp = parent; | |
241 | return p; | |
242 | } | |
243 | ||
244 | /** | |
245 | * pcpu_chunk_addr_search - search for chunk containing specified address | |
246 | * @addr: address to search for | |
247 | * | |
248 | * Look for chunk which might contain @addr. More specifically, it | |
249 | * searchs for the chunk with the highest start address which isn't | |
250 | * beyond @addr. | |
251 | * | |
252 | * RETURNS: | |
253 | * The address of the found chunk. | |
254 | */ | |
255 | static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr) | |
256 | { | |
257 | struct rb_node *n, *parent; | |
258 | struct pcpu_chunk *chunk; | |
259 | ||
260 | n = *pcpu_chunk_rb_search(addr, &parent); | |
261 | if (!n) { | |
262 | /* no exactly matching chunk, the parent is the closest */ | |
263 | n = parent; | |
264 | BUG_ON(!n); | |
265 | } | |
266 | chunk = rb_entry(n, struct pcpu_chunk, rb_node); | |
267 | ||
268 | if (addr < chunk->vm->addr) { | |
269 | /* the parent was the next one, look for the previous one */ | |
270 | n = rb_prev(n); | |
271 | BUG_ON(!n); | |
272 | chunk = rb_entry(n, struct pcpu_chunk, rb_node); | |
273 | } | |
274 | ||
275 | return chunk; | |
276 | } | |
277 | ||
278 | /** | |
279 | * pcpu_chunk_addr_insert - insert chunk into address rb tree | |
280 | * @new: chunk to insert | |
281 | * | |
282 | * Insert @new into address rb tree. | |
283 | */ | |
284 | static void pcpu_chunk_addr_insert(struct pcpu_chunk *new) | |
285 | { | |
286 | struct rb_node **p, *parent; | |
287 | ||
288 | p = pcpu_chunk_rb_search(new->vm->addr, &parent); | |
289 | BUG_ON(*p); | |
290 | rb_link_node(&new->rb_node, parent, p); | |
291 | rb_insert_color(&new->rb_node, &pcpu_addr_root); | |
292 | } | |
293 | ||
294 | /** | |
295 | * pcpu_split_block - split a map block | |
296 | * @chunk: chunk of interest | |
297 | * @i: index of map block to split | |
cae3aeb8 TH |
298 | * @head: head size in bytes (can be 0) |
299 | * @tail: tail size in bytes (can be 0) | |
fbf59bc9 TH |
300 | * |
301 | * Split the @i'th map block into two or three blocks. If @head is | |
302 | * non-zero, @head bytes block is inserted before block @i moving it | |
303 | * to @i+1 and reducing its size by @head bytes. | |
304 | * | |
305 | * If @tail is non-zero, the target block, which can be @i or @i+1 | |
306 | * depending on @head, is reduced by @tail bytes and @tail byte block | |
307 | * is inserted after the target block. | |
308 | * | |
309 | * RETURNS: | |
310 | * 0 on success, -errno on failure. | |
311 | */ | |
312 | static int pcpu_split_block(struct pcpu_chunk *chunk, int i, int head, int tail) | |
313 | { | |
314 | int nr_extra = !!head + !!tail; | |
315 | int target = chunk->map_used + nr_extra; | |
316 | ||
317 | /* reallocation required? */ | |
318 | if (chunk->map_alloc < target) { | |
319 | int new_alloc = chunk->map_alloc; | |
320 | int *new; | |
321 | ||
322 | while (new_alloc < target) | |
323 | new_alloc *= 2; | |
324 | ||
325 | new = pcpu_realloc(chunk->map, | |
326 | chunk->map_alloc * sizeof(new[0]), | |
327 | new_alloc * sizeof(new[0])); | |
328 | if (!new) | |
329 | return -ENOMEM; | |
330 | ||
331 | chunk->map_alloc = new_alloc; | |
332 | chunk->map = new; | |
333 | } | |
334 | ||
335 | /* insert a new subblock */ | |
336 | memmove(&chunk->map[i + nr_extra], &chunk->map[i], | |
337 | sizeof(chunk->map[0]) * (chunk->map_used - i)); | |
338 | chunk->map_used += nr_extra; | |
339 | ||
340 | if (head) { | |
341 | chunk->map[i + 1] = chunk->map[i] - head; | |
342 | chunk->map[i++] = head; | |
343 | } | |
344 | if (tail) { | |
345 | chunk->map[i++] -= tail; | |
346 | chunk->map[i] = tail; | |
347 | } | |
348 | return 0; | |
349 | } | |
350 | ||
351 | /** | |
352 | * pcpu_alloc_area - allocate area from a pcpu_chunk | |
353 | * @chunk: chunk of interest | |
cae3aeb8 | 354 | * @size: wanted size in bytes |
fbf59bc9 TH |
355 | * @align: wanted align |
356 | * | |
357 | * Try to allocate @size bytes area aligned at @align from @chunk. | |
358 | * Note that this function only allocates the offset. It doesn't | |
359 | * populate or map the area. | |
360 | * | |
361 | * RETURNS: | |
362 | * Allocated offset in @chunk on success, -errno on failure. | |
363 | */ | |
364 | static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align) | |
365 | { | |
366 | int oslot = pcpu_chunk_slot(chunk); | |
367 | int max_contig = 0; | |
368 | int i, off; | |
369 | ||
370 | /* | |
371 | * The static chunk initially doesn't have map attached | |
372 | * because kmalloc wasn't available during init. Give it one. | |
373 | */ | |
374 | if (unlikely(!chunk->map)) { | |
375 | chunk->map = pcpu_realloc(NULL, 0, | |
376 | PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0])); | |
377 | if (!chunk->map) | |
378 | return -ENOMEM; | |
379 | ||
380 | chunk->map_alloc = PCPU_DFL_MAP_ALLOC; | |
381 | chunk->map[chunk->map_used++] = -pcpu_static_size; | |
382 | if (chunk->free_size) | |
383 | chunk->map[chunk->map_used++] = chunk->free_size; | |
384 | } | |
385 | ||
386 | for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) { | |
387 | bool is_last = i + 1 == chunk->map_used; | |
388 | int head, tail; | |
389 | ||
390 | /* extra for alignment requirement */ | |
391 | head = ALIGN(off, align) - off; | |
392 | BUG_ON(i == 0 && head != 0); | |
393 | ||
394 | if (chunk->map[i] < 0) | |
395 | continue; | |
396 | if (chunk->map[i] < head + size) { | |
397 | max_contig = max(chunk->map[i], max_contig); | |
398 | continue; | |
399 | } | |
400 | ||
401 | /* | |
402 | * If head is small or the previous block is free, | |
403 | * merge'em. Note that 'small' is defined as smaller | |
404 | * than sizeof(int), which is very small but isn't too | |
405 | * uncommon for percpu allocations. | |
406 | */ | |
407 | if (head && (head < sizeof(int) || chunk->map[i - 1] > 0)) { | |
408 | if (chunk->map[i - 1] > 0) | |
409 | chunk->map[i - 1] += head; | |
410 | else { | |
411 | chunk->map[i - 1] -= head; | |
412 | chunk->free_size -= head; | |
413 | } | |
414 | chunk->map[i] -= head; | |
415 | off += head; | |
416 | head = 0; | |
417 | } | |
418 | ||
419 | /* if tail is small, just keep it around */ | |
420 | tail = chunk->map[i] - head - size; | |
421 | if (tail < sizeof(int)) | |
422 | tail = 0; | |
423 | ||
424 | /* split if warranted */ | |
425 | if (head || tail) { | |
426 | if (pcpu_split_block(chunk, i, head, tail)) | |
427 | return -ENOMEM; | |
428 | if (head) { | |
429 | i++; | |
430 | off += head; | |
431 | max_contig = max(chunk->map[i - 1], max_contig); | |
432 | } | |
433 | if (tail) | |
434 | max_contig = max(chunk->map[i + 1], max_contig); | |
435 | } | |
436 | ||
437 | /* update hint and mark allocated */ | |
438 | if (is_last) | |
439 | chunk->contig_hint = max_contig; /* fully scanned */ | |
440 | else | |
441 | chunk->contig_hint = max(chunk->contig_hint, | |
442 | max_contig); | |
443 | ||
444 | chunk->free_size -= chunk->map[i]; | |
445 | chunk->map[i] = -chunk->map[i]; | |
446 | ||
447 | pcpu_chunk_relocate(chunk, oslot); | |
448 | return off; | |
449 | } | |
450 | ||
451 | chunk->contig_hint = max_contig; /* fully scanned */ | |
452 | pcpu_chunk_relocate(chunk, oslot); | |
453 | ||
454 | /* | |
455 | * Tell the upper layer that this chunk has no area left. | |
456 | * Note that this is not an error condition but a notification | |
457 | * to upper layer that it needs to look at other chunks. | |
458 | * -ENOSPC is chosen as it isn't used in memory subsystem and | |
459 | * matches the meaning in a way. | |
460 | */ | |
461 | return -ENOSPC; | |
462 | } | |
463 | ||
464 | /** | |
465 | * pcpu_free_area - free area to a pcpu_chunk | |
466 | * @chunk: chunk of interest | |
467 | * @freeme: offset of area to free | |
468 | * | |
469 | * Free area starting from @freeme to @chunk. Note that this function | |
470 | * only modifies the allocation map. It doesn't depopulate or unmap | |
471 | * the area. | |
472 | */ | |
473 | static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme) | |
474 | { | |
475 | int oslot = pcpu_chunk_slot(chunk); | |
476 | int i, off; | |
477 | ||
478 | for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++])) | |
479 | if (off == freeme) | |
480 | break; | |
481 | BUG_ON(off != freeme); | |
482 | BUG_ON(chunk->map[i] > 0); | |
483 | ||
484 | chunk->map[i] = -chunk->map[i]; | |
485 | chunk->free_size += chunk->map[i]; | |
486 | ||
487 | /* merge with previous? */ | |
488 | if (i > 0 && chunk->map[i - 1] >= 0) { | |
489 | chunk->map[i - 1] += chunk->map[i]; | |
490 | chunk->map_used--; | |
491 | memmove(&chunk->map[i], &chunk->map[i + 1], | |
492 | (chunk->map_used - i) * sizeof(chunk->map[0])); | |
493 | i--; | |
494 | } | |
495 | /* merge with next? */ | |
496 | if (i + 1 < chunk->map_used && chunk->map[i + 1] >= 0) { | |
497 | chunk->map[i] += chunk->map[i + 1]; | |
498 | chunk->map_used--; | |
499 | memmove(&chunk->map[i + 1], &chunk->map[i + 2], | |
500 | (chunk->map_used - (i + 1)) * sizeof(chunk->map[0])); | |
501 | } | |
502 | ||
503 | chunk->contig_hint = max(chunk->map[i], chunk->contig_hint); | |
504 | pcpu_chunk_relocate(chunk, oslot); | |
505 | } | |
506 | ||
507 | /** | |
508 | * pcpu_unmap - unmap pages out of a pcpu_chunk | |
509 | * @chunk: chunk of interest | |
510 | * @page_start: page index of the first page to unmap | |
511 | * @page_end: page index of the last page to unmap + 1 | |
512 | * @flush: whether to flush cache and tlb or not | |
513 | * | |
514 | * For each cpu, unmap pages [@page_start,@page_end) out of @chunk. | |
515 | * If @flush is true, vcache is flushed before unmapping and tlb | |
516 | * after. | |
517 | */ | |
518 | static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end, | |
519 | bool flush) | |
520 | { | |
521 | unsigned int last = num_possible_cpus() - 1; | |
522 | unsigned int cpu; | |
523 | ||
8d408b4b TH |
524 | /* unmap must not be done on immutable chunk */ |
525 | WARN_ON(chunk->immutable); | |
526 | ||
fbf59bc9 TH |
527 | /* |
528 | * Each flushing trial can be very expensive, issue flush on | |
529 | * the whole region at once rather than doing it for each cpu. | |
530 | * This could be an overkill but is more scalable. | |
531 | */ | |
532 | if (flush) | |
533 | flush_cache_vunmap(pcpu_chunk_addr(chunk, 0, page_start), | |
534 | pcpu_chunk_addr(chunk, last, page_end)); | |
535 | ||
536 | for_each_possible_cpu(cpu) | |
537 | unmap_kernel_range_noflush( | |
538 | pcpu_chunk_addr(chunk, cpu, page_start), | |
539 | (page_end - page_start) << PAGE_SHIFT); | |
540 | ||
541 | /* ditto as flush_cache_vunmap() */ | |
542 | if (flush) | |
543 | flush_tlb_kernel_range(pcpu_chunk_addr(chunk, 0, page_start), | |
544 | pcpu_chunk_addr(chunk, last, page_end)); | |
545 | } | |
546 | ||
547 | /** | |
548 | * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk | |
549 | * @chunk: chunk to depopulate | |
550 | * @off: offset to the area to depopulate | |
cae3aeb8 | 551 | * @size: size of the area to depopulate in bytes |
fbf59bc9 TH |
552 | * @flush: whether to flush cache and tlb or not |
553 | * | |
554 | * For each cpu, depopulate and unmap pages [@page_start,@page_end) | |
555 | * from @chunk. If @flush is true, vcache is flushed before unmapping | |
556 | * and tlb after. | |
557 | */ | |
cae3aeb8 TH |
558 | static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size, |
559 | bool flush) | |
fbf59bc9 TH |
560 | { |
561 | int page_start = PFN_DOWN(off); | |
562 | int page_end = PFN_UP(off + size); | |
563 | int unmap_start = -1; | |
564 | int uninitialized_var(unmap_end); | |
565 | unsigned int cpu; | |
566 | int i; | |
567 | ||
568 | for (i = page_start; i < page_end; i++) { | |
569 | for_each_possible_cpu(cpu) { | |
570 | struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i); | |
571 | ||
572 | if (!*pagep) | |
573 | continue; | |
574 | ||
575 | __free_page(*pagep); | |
576 | ||
577 | /* | |
578 | * If it's partial depopulation, it might get | |
579 | * populated or depopulated again. Mark the | |
580 | * page gone. | |
581 | */ | |
582 | *pagep = NULL; | |
583 | ||
584 | unmap_start = unmap_start < 0 ? i : unmap_start; | |
585 | unmap_end = i + 1; | |
586 | } | |
587 | } | |
588 | ||
589 | if (unmap_start >= 0) | |
590 | pcpu_unmap(chunk, unmap_start, unmap_end, flush); | |
591 | } | |
592 | ||
593 | /** | |
594 | * pcpu_map - map pages into a pcpu_chunk | |
595 | * @chunk: chunk of interest | |
596 | * @page_start: page index of the first page to map | |
597 | * @page_end: page index of the last page to map + 1 | |
598 | * | |
599 | * For each cpu, map pages [@page_start,@page_end) into @chunk. | |
600 | * vcache is flushed afterwards. | |
601 | */ | |
602 | static int pcpu_map(struct pcpu_chunk *chunk, int page_start, int page_end) | |
603 | { | |
604 | unsigned int last = num_possible_cpus() - 1; | |
605 | unsigned int cpu; | |
606 | int err; | |
607 | ||
8d408b4b TH |
608 | /* map must not be done on immutable chunk */ |
609 | WARN_ON(chunk->immutable); | |
610 | ||
fbf59bc9 TH |
611 | for_each_possible_cpu(cpu) { |
612 | err = map_kernel_range_noflush( | |
613 | pcpu_chunk_addr(chunk, cpu, page_start), | |
614 | (page_end - page_start) << PAGE_SHIFT, | |
615 | PAGE_KERNEL, | |
616 | pcpu_chunk_pagep(chunk, cpu, page_start)); | |
617 | if (err < 0) | |
618 | return err; | |
619 | } | |
620 | ||
621 | /* flush at once, please read comments in pcpu_unmap() */ | |
622 | flush_cache_vmap(pcpu_chunk_addr(chunk, 0, page_start), | |
623 | pcpu_chunk_addr(chunk, last, page_end)); | |
624 | return 0; | |
625 | } | |
626 | ||
627 | /** | |
628 | * pcpu_populate_chunk - populate and map an area of a pcpu_chunk | |
629 | * @chunk: chunk of interest | |
630 | * @off: offset to the area to populate | |
cae3aeb8 | 631 | * @size: size of the area to populate in bytes |
fbf59bc9 TH |
632 | * |
633 | * For each cpu, populate and map pages [@page_start,@page_end) into | |
634 | * @chunk. The area is cleared on return. | |
635 | */ | |
636 | static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) | |
637 | { | |
638 | const gfp_t alloc_mask = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD; | |
639 | int page_start = PFN_DOWN(off); | |
640 | int page_end = PFN_UP(off + size); | |
641 | int map_start = -1; | |
02d51fdf | 642 | int uninitialized_var(map_end); |
fbf59bc9 TH |
643 | unsigned int cpu; |
644 | int i; | |
645 | ||
646 | for (i = page_start; i < page_end; i++) { | |
647 | if (pcpu_chunk_page_occupied(chunk, i)) { | |
648 | if (map_start >= 0) { | |
649 | if (pcpu_map(chunk, map_start, map_end)) | |
650 | goto err; | |
651 | map_start = -1; | |
652 | } | |
653 | continue; | |
654 | } | |
655 | ||
656 | map_start = map_start < 0 ? i : map_start; | |
657 | map_end = i + 1; | |
658 | ||
659 | for_each_possible_cpu(cpu) { | |
660 | struct page **pagep = pcpu_chunk_pagep(chunk, cpu, i); | |
661 | ||
662 | *pagep = alloc_pages_node(cpu_to_node(cpu), | |
663 | alloc_mask, 0); | |
664 | if (!*pagep) | |
665 | goto err; | |
666 | } | |
667 | } | |
668 | ||
669 | if (map_start >= 0 && pcpu_map(chunk, map_start, map_end)) | |
670 | goto err; | |
671 | ||
672 | for_each_possible_cpu(cpu) | |
d9b55eeb | 673 | memset(chunk->vm->addr + cpu * pcpu_unit_size + off, 0, |
fbf59bc9 TH |
674 | size); |
675 | ||
676 | return 0; | |
677 | err: | |
678 | /* likely under heavy memory pressure, give memory back */ | |
679 | pcpu_depopulate_chunk(chunk, off, size, true); | |
680 | return -ENOMEM; | |
681 | } | |
682 | ||
683 | static void free_pcpu_chunk(struct pcpu_chunk *chunk) | |
684 | { | |
685 | if (!chunk) | |
686 | return; | |
687 | if (chunk->vm) | |
688 | free_vm_area(chunk->vm); | |
689 | pcpu_realloc(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]), 0); | |
690 | kfree(chunk); | |
691 | } | |
692 | ||
693 | static struct pcpu_chunk *alloc_pcpu_chunk(void) | |
694 | { | |
695 | struct pcpu_chunk *chunk; | |
696 | ||
697 | chunk = kzalloc(pcpu_chunk_struct_size, GFP_KERNEL); | |
698 | if (!chunk) | |
699 | return NULL; | |
700 | ||
701 | chunk->map = pcpu_realloc(NULL, 0, | |
702 | PCPU_DFL_MAP_ALLOC * sizeof(chunk->map[0])); | |
703 | chunk->map_alloc = PCPU_DFL_MAP_ALLOC; | |
704 | chunk->map[chunk->map_used++] = pcpu_unit_size; | |
705 | ||
706 | chunk->vm = get_vm_area(pcpu_chunk_size, GFP_KERNEL); | |
707 | if (!chunk->vm) { | |
708 | free_pcpu_chunk(chunk); | |
709 | return NULL; | |
710 | } | |
711 | ||
712 | INIT_LIST_HEAD(&chunk->list); | |
713 | chunk->free_size = pcpu_unit_size; | |
714 | chunk->contig_hint = pcpu_unit_size; | |
715 | ||
716 | return chunk; | |
717 | } | |
718 | ||
719 | /** | |
720 | * __alloc_percpu - allocate percpu area | |
cae3aeb8 | 721 | * @size: size of area to allocate in bytes |
fbf59bc9 TH |
722 | * @align: alignment of area (max PAGE_SIZE) |
723 | * | |
724 | * Allocate percpu area of @size bytes aligned at @align. Might | |
725 | * sleep. Might trigger writeouts. | |
726 | * | |
727 | * RETURNS: | |
728 | * Percpu pointer to the allocated area on success, NULL on failure. | |
729 | */ | |
730 | void *__alloc_percpu(size_t size, size_t align) | |
731 | { | |
732 | void *ptr = NULL; | |
733 | struct pcpu_chunk *chunk; | |
734 | int slot, off; | |
735 | ||
8d408b4b | 736 | if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) { |
fbf59bc9 TH |
737 | WARN(true, "illegal size (%zu) or align (%zu) for " |
738 | "percpu allocation\n", size, align); | |
739 | return NULL; | |
740 | } | |
741 | ||
742 | mutex_lock(&pcpu_mutex); | |
743 | ||
744 | /* allocate area */ | |
745 | for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) { | |
746 | list_for_each_entry(chunk, &pcpu_slot[slot], list) { | |
747 | if (size > chunk->contig_hint) | |
748 | continue; | |
749 | off = pcpu_alloc_area(chunk, size, align); | |
750 | if (off >= 0) | |
751 | goto area_found; | |
752 | if (off != -ENOSPC) | |
753 | goto out_unlock; | |
754 | } | |
755 | } | |
756 | ||
757 | /* hmmm... no space left, create a new chunk */ | |
758 | chunk = alloc_pcpu_chunk(); | |
759 | if (!chunk) | |
760 | goto out_unlock; | |
761 | pcpu_chunk_relocate(chunk, -1); | |
762 | pcpu_chunk_addr_insert(chunk); | |
763 | ||
764 | off = pcpu_alloc_area(chunk, size, align); | |
765 | if (off < 0) | |
766 | goto out_unlock; | |
767 | ||
768 | area_found: | |
769 | /* populate, map and clear the area */ | |
770 | if (pcpu_populate_chunk(chunk, off, size)) { | |
771 | pcpu_free_area(chunk, off); | |
772 | goto out_unlock; | |
773 | } | |
774 | ||
775 | ptr = __addr_to_pcpu_ptr(chunk->vm->addr + off); | |
776 | out_unlock: | |
777 | mutex_unlock(&pcpu_mutex); | |
778 | return ptr; | |
779 | } | |
780 | EXPORT_SYMBOL_GPL(__alloc_percpu); | |
781 | ||
782 | static void pcpu_kill_chunk(struct pcpu_chunk *chunk) | |
783 | { | |
8d408b4b | 784 | WARN_ON(chunk->immutable); |
fbf59bc9 TH |
785 | pcpu_depopulate_chunk(chunk, 0, pcpu_unit_size, false); |
786 | list_del(&chunk->list); | |
787 | rb_erase(&chunk->rb_node, &pcpu_addr_root); | |
788 | free_pcpu_chunk(chunk); | |
789 | } | |
790 | ||
791 | /** | |
792 | * free_percpu - free percpu area | |
793 | * @ptr: pointer to area to free | |
794 | * | |
795 | * Free percpu area @ptr. Might sleep. | |
796 | */ | |
797 | void free_percpu(void *ptr) | |
798 | { | |
799 | void *addr = __pcpu_ptr_to_addr(ptr); | |
800 | struct pcpu_chunk *chunk; | |
801 | int off; | |
802 | ||
803 | if (!ptr) | |
804 | return; | |
805 | ||
806 | mutex_lock(&pcpu_mutex); | |
807 | ||
808 | chunk = pcpu_chunk_addr_search(addr); | |
809 | off = addr - chunk->vm->addr; | |
810 | ||
811 | pcpu_free_area(chunk, off); | |
812 | ||
813 | /* the chunk became fully free, kill one if there are other free ones */ | |
814 | if (chunk->free_size == pcpu_unit_size) { | |
815 | struct pcpu_chunk *pos; | |
816 | ||
817 | list_for_each_entry(pos, | |
818 | &pcpu_slot[pcpu_chunk_slot(chunk)], list) | |
819 | if (pos != chunk) { | |
820 | pcpu_kill_chunk(pos); | |
821 | break; | |
822 | } | |
823 | } | |
824 | ||
825 | mutex_unlock(&pcpu_mutex); | |
826 | } | |
827 | EXPORT_SYMBOL_GPL(free_percpu); | |
828 | ||
829 | /** | |
8d408b4b TH |
830 | * pcpu_setup_first_chunk - initialize the first percpu chunk |
831 | * @get_page_fn: callback to fetch page pointer | |
832 | * @static_size: the size of static percpu area in bytes | |
833 | * @unit_size: unit size in bytes, must be multiple of PAGE_SIZE, 0 for auto | |
2441d15c | 834 | * @dyn_size: free size for dynamic allocation in bytes, 0 for auto |
8d408b4b TH |
835 | * @base_addr: mapped address, NULL for auto |
836 | * @populate_pte_fn: callback to allocate pagetable, NULL if unnecessary | |
837 | * | |
838 | * Initialize the first percpu chunk which contains the kernel static | |
839 | * perpcu area. This function is to be called from arch percpu area | |
840 | * setup path. The first two parameters are mandatory. The rest are | |
841 | * optional. | |
842 | * | |
843 | * @get_page_fn() should return pointer to percpu page given cpu | |
844 | * number and page number. It should at least return enough pages to | |
845 | * cover the static area. The returned pages for static area should | |
846 | * have been initialized with valid data. If @unit_size is specified, | |
847 | * it can also return pages after the static area. NULL return | |
848 | * indicates end of pages for the cpu. Note that @get_page_fn() must | |
849 | * return the same number of pages for all cpus. | |
850 | * | |
851 | * @unit_size, if non-zero, determines unit size and must be aligned | |
2441d15c | 852 | * to PAGE_SIZE and equal to or larger than @static_size + @dyn_size. |
8d408b4b | 853 | * |
2441d15c | 854 | * @dyn_size determines the number of free bytes after the static |
8d408b4b TH |
855 | * area in the first chunk. If zero, whatever left is available. |
856 | * Specifying non-zero value make percpu leave the area after | |
2441d15c | 857 | * @static_size + @dyn_size alone. |
8d408b4b TH |
858 | * |
859 | * Non-null @base_addr means that the caller already allocated virtual | |
860 | * region for the first chunk and mapped it. percpu must not mess | |
861 | * with the chunk. Note that @base_addr with 0 @unit_size or non-NULL | |
862 | * @populate_pte_fn doesn't make any sense. | |
863 | * | |
864 | * @populate_pte_fn is used to populate the pagetable. NULL means the | |
865 | * caller already populated the pagetable. | |
fbf59bc9 TH |
866 | * |
867 | * RETURNS: | |
868 | * The determined pcpu_unit_size which can be used to initialize | |
869 | * percpu access. | |
870 | */ | |
8d408b4b TH |
871 | size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn, |
872 | size_t static_size, size_t unit_size, | |
2441d15c | 873 | size_t dyn_size, void *base_addr, |
8d408b4b | 874 | pcpu_populate_pte_fn_t populate_pte_fn) |
fbf59bc9 | 875 | { |
2441d15c TH |
876 | static struct vm_struct first_vm; |
877 | struct pcpu_chunk *schunk; | |
fbf59bc9 | 878 | unsigned int cpu; |
8d408b4b | 879 | int nr_pages; |
fbf59bc9 TH |
880 | int err, i; |
881 | ||
8d408b4b TH |
882 | /* santiy checks */ |
883 | BUG_ON(!static_size); | |
2441d15c TH |
884 | BUG_ON(!unit_size && dyn_size); |
885 | BUG_ON(unit_size && unit_size < static_size + dyn_size); | |
8d408b4b TH |
886 | BUG_ON(unit_size & ~PAGE_MASK); |
887 | BUG_ON(base_addr && !unit_size); | |
888 | BUG_ON(base_addr && populate_pte_fn); | |
fbf59bc9 | 889 | |
8d408b4b TH |
890 | if (unit_size) |
891 | pcpu_unit_pages = unit_size >> PAGE_SHIFT; | |
892 | else | |
893 | pcpu_unit_pages = max_t(int, PCPU_MIN_UNIT_SIZE >> PAGE_SHIFT, | |
894 | PFN_UP(static_size)); | |
895 | ||
896 | pcpu_static_size = static_size; | |
d9b55eeb | 897 | pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT; |
fbf59bc9 | 898 | pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size; |
fbf59bc9 | 899 | pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) |
cb83b42e | 900 | + num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *); |
fbf59bc9 | 901 | |
d9b55eeb TH |
902 | /* |
903 | * Allocate chunk slots. The additional last slot is for | |
904 | * empty chunks. | |
905 | */ | |
906 | pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2; | |
fbf59bc9 TH |
907 | pcpu_slot = alloc_bootmem(pcpu_nr_slots * sizeof(pcpu_slot[0])); |
908 | for (i = 0; i < pcpu_nr_slots; i++) | |
909 | INIT_LIST_HEAD(&pcpu_slot[i]); | |
910 | ||
2441d15c TH |
911 | /* init static chunk */ |
912 | schunk = alloc_bootmem(pcpu_chunk_struct_size); | |
913 | INIT_LIST_HEAD(&schunk->list); | |
914 | schunk->vm = &first_vm; | |
8d408b4b | 915 | |
2441d15c TH |
916 | if (dyn_size) |
917 | schunk->free_size = dyn_size; | |
8d408b4b | 918 | else |
2441d15c | 919 | schunk->free_size = pcpu_unit_size - pcpu_static_size; |
8d408b4b | 920 | |
2441d15c | 921 | schunk->contig_hint = schunk->free_size; |
fbf59bc9 | 922 | |
8d408b4b | 923 | /* allocate vm address */ |
2441d15c TH |
924 | first_vm.flags = VM_ALLOC; |
925 | first_vm.size = pcpu_chunk_size; | |
8d408b4b TH |
926 | |
927 | if (!base_addr) | |
2441d15c | 928 | vm_area_register_early(&first_vm, PAGE_SIZE); |
8d408b4b TH |
929 | else { |
930 | /* | |
931 | * Pages already mapped. No need to remap into | |
932 | * vmalloc area. In this case the static chunk can't | |
933 | * be mapped or unmapped by percpu and is marked | |
934 | * immutable. | |
935 | */ | |
2441d15c TH |
936 | first_vm.addr = base_addr; |
937 | schunk->immutable = true; | |
8d408b4b TH |
938 | } |
939 | ||
940 | /* assign pages */ | |
941 | nr_pages = -1; | |
fbf59bc9 | 942 | for_each_possible_cpu(cpu) { |
8d408b4b TH |
943 | for (i = 0; i < pcpu_unit_pages; i++) { |
944 | struct page *page = get_page_fn(cpu, i); | |
945 | ||
946 | if (!page) | |
947 | break; | |
2441d15c | 948 | *pcpu_chunk_pagep(schunk, cpu, i) = page; |
fbf59bc9 | 949 | } |
8d408b4b TH |
950 | |
951 | BUG_ON(i < PFN_UP(pcpu_static_size)); | |
952 | ||
953 | if (nr_pages < 0) | |
954 | nr_pages = i; | |
955 | else | |
956 | BUG_ON(nr_pages != i); | |
fbf59bc9 TH |
957 | } |
958 | ||
8d408b4b TH |
959 | /* map them */ |
960 | if (populate_pte_fn) { | |
961 | for_each_possible_cpu(cpu) | |
962 | for (i = 0; i < nr_pages; i++) | |
2441d15c | 963 | populate_pte_fn(pcpu_chunk_addr(schunk, |
8d408b4b TH |
964 | cpu, i)); |
965 | ||
2441d15c | 966 | err = pcpu_map(schunk, 0, nr_pages); |
8d408b4b TH |
967 | if (err) |
968 | panic("failed to setup static percpu area, err=%d\n", | |
969 | err); | |
970 | } | |
fbf59bc9 | 971 | |
2441d15c TH |
972 | /* link the first chunk in */ |
973 | pcpu_chunk_relocate(schunk, -1); | |
974 | pcpu_chunk_addr_insert(schunk); | |
fbf59bc9 TH |
975 | |
976 | /* we're done */ | |
2441d15c | 977 | pcpu_base_addr = (void *)pcpu_chunk_addr(schunk, 0, 0); |
fbf59bc9 TH |
978 | return pcpu_unit_size; |
979 | } |