Loading...
1/*
2 * mm/percpu-vm.c - vmalloc area based chunk allocation
3 *
4 * Copyright (C) 2010 SUSE Linux Products GmbH
5 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
6 *
7 * This file is released under the GPLv2.
8 *
9 * Chunks are mapped into vmalloc areas and populated page by page.
10 * This is the default chunk allocator.
11 */
12
13static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
14 unsigned int cpu, int page_idx)
15{
16 /* must not be used on pre-mapped chunk */
17 WARN_ON(chunk->immutable);
18
19 return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
20}
21
22/**
23 * pcpu_get_pages_and_bitmap - get temp pages array and bitmap
24 * @chunk: chunk of interest
25 * @bitmapp: output parameter for bitmap
26 * @may_alloc: may allocate the array
27 *
28 * Returns pointer to array of pointers to struct page and bitmap,
29 * both of which can be indexed with pcpu_page_idx(). The returned
30 * array is cleared to zero and *@bitmapp is copied from
31 * @chunk->populated. Note that there is only one array and bitmap
32 * and access exclusion is the caller's responsibility.
33 *
34 * CONTEXT:
35 * pcpu_alloc_mutex and does GFP_KERNEL allocation if @may_alloc.
36 * Otherwise, don't care.
37 *
38 * RETURNS:
39 * Pointer to temp pages array on success, NULL on failure.
40 */
41static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk,
42 unsigned long **bitmapp,
43 bool may_alloc)
44{
45 static struct page **pages;
46 static unsigned long *bitmap;
47 size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
48 size_t bitmap_size = BITS_TO_LONGS(pcpu_unit_pages) *
49 sizeof(unsigned long);
50
51 if (!pages || !bitmap) {
52 if (may_alloc && !pages)
53 pages = pcpu_mem_zalloc(pages_size);
54 if (may_alloc && !bitmap)
55 bitmap = pcpu_mem_zalloc(bitmap_size);
56 if (!pages || !bitmap)
57 return NULL;
58 }
59
60 bitmap_copy(bitmap, chunk->populated, pcpu_unit_pages);
61
62 *bitmapp = bitmap;
63 return pages;
64}
65
66/**
67 * pcpu_free_pages - free pages which were allocated for @chunk
68 * @chunk: chunk pages were allocated for
69 * @pages: array of pages to be freed, indexed by pcpu_page_idx()
70 * @populated: populated bitmap
71 * @page_start: page index of the first page to be freed
72 * @page_end: page index of the last page to be freed + 1
73 *
74 * Free pages [@page_start and @page_end) in @pages for all units.
75 * The pages were allocated for @chunk.
76 */
77static void pcpu_free_pages(struct pcpu_chunk *chunk,
78 struct page **pages, unsigned long *populated,
79 int page_start, int page_end)
80{
81 unsigned int cpu;
82 int i;
83
84 for_each_possible_cpu(cpu) {
85 for (i = page_start; i < page_end; i++) {
86 struct page *page = pages[pcpu_page_idx(cpu, i)];
87
88 if (page)
89 __free_page(page);
90 }
91 }
92}
93
94/**
95 * pcpu_alloc_pages - allocates pages for @chunk
96 * @chunk: target chunk
97 * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
98 * @populated: populated bitmap
99 * @page_start: page index of the first page to be allocated
100 * @page_end: page index of the last page to be allocated + 1
101 *
102 * Allocate pages [@page_start,@page_end) into @pages for all units.
103 * The allocation is for @chunk. Percpu core doesn't care about the
104 * content of @pages and will pass it verbatim to pcpu_map_pages().
105 */
106static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
107 struct page **pages, unsigned long *populated,
108 int page_start, int page_end)
109{
110 const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
111 unsigned int cpu;
112 int i;
113
114 for_each_possible_cpu(cpu) {
115 for (i = page_start; i < page_end; i++) {
116 struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
117
118 *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
119 if (!*pagep) {
120 pcpu_free_pages(chunk, pages, populated,
121 page_start, page_end);
122 return -ENOMEM;
123 }
124 }
125 }
126 return 0;
127}
128
129/**
130 * pcpu_pre_unmap_flush - flush cache prior to unmapping
131 * @chunk: chunk the regions to be flushed belongs to
132 * @page_start: page index of the first page to be flushed
133 * @page_end: page index of the last page to be flushed + 1
134 *
135 * Pages in [@page_start,@page_end) of @chunk are about to be
136 * unmapped. Flush cache. As each flushing trial can be very
137 * expensive, issue flush on the whole region at once rather than
138 * doing it for each cpu. This could be an overkill but is more
139 * scalable.
140 */
141static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
142 int page_start, int page_end)
143{
144 flush_cache_vunmap(
145 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
146 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
147}
148
149static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
150{
151 unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
152}
153
154/**
155 * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
156 * @chunk: chunk of interest
157 * @pages: pages array which can be used to pass information to free
158 * @populated: populated bitmap
159 * @page_start: page index of the first page to unmap
160 * @page_end: page index of the last page to unmap + 1
161 *
162 * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
163 * Corresponding elements in @pages were cleared by the caller and can
164 * be used to carry information to pcpu_free_pages() which will be
165 * called after all unmaps are finished. The caller should call
166 * proper pre/post flush functions.
167 */
168static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
169 struct page **pages, unsigned long *populated,
170 int page_start, int page_end)
171{
172 unsigned int cpu;
173 int i;
174
175 for_each_possible_cpu(cpu) {
176 for (i = page_start; i < page_end; i++) {
177 struct page *page;
178
179 page = pcpu_chunk_page(chunk, cpu, i);
180 WARN_ON(!page);
181 pages[pcpu_page_idx(cpu, i)] = page;
182 }
183 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
184 page_end - page_start);
185 }
186
187 bitmap_clear(populated, page_start, page_end - page_start);
188}
189
190/**
191 * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
192 * @chunk: pcpu_chunk the regions to be flushed belong to
193 * @page_start: page index of the first page to be flushed
194 * @page_end: page index of the last page to be flushed + 1
195 *
196 * Pages [@page_start,@page_end) of @chunk have been unmapped. Flush
197 * TLB for the regions. This can be skipped if the area is to be
198 * returned to vmalloc as vmalloc will handle TLB flushing lazily.
199 *
200 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
201 * for the whole region.
202 */
203static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
204 int page_start, int page_end)
205{
206 flush_tlb_kernel_range(
207 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
208 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
209}
210
211static int __pcpu_map_pages(unsigned long addr, struct page **pages,
212 int nr_pages)
213{
214 return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
215 PAGE_KERNEL, pages);
216}
217
218/**
219 * pcpu_map_pages - map pages into a pcpu_chunk
220 * @chunk: chunk of interest
221 * @pages: pages array containing pages to be mapped
222 * @populated: populated bitmap
223 * @page_start: page index of the first page to map
224 * @page_end: page index of the last page to map + 1
225 *
226 * For each cpu, map pages [@page_start,@page_end) into @chunk. The
227 * caller is responsible for calling pcpu_post_map_flush() after all
228 * mappings are complete.
229 *
230 * This function is responsible for setting corresponding bits in
231 * @chunk->populated bitmap and whatever is necessary for reverse
232 * lookup (addr -> chunk).
233 */
234static int pcpu_map_pages(struct pcpu_chunk *chunk,
235 struct page **pages, unsigned long *populated,
236 int page_start, int page_end)
237{
238 unsigned int cpu, tcpu;
239 int i, err;
240
241 for_each_possible_cpu(cpu) {
242 err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
243 &pages[pcpu_page_idx(cpu, page_start)],
244 page_end - page_start);
245 if (err < 0)
246 goto err;
247 }
248
249 /* mapping successful, link chunk and mark populated */
250 for (i = page_start; i < page_end; i++) {
251 for_each_possible_cpu(cpu)
252 pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
253 chunk);
254 __set_bit(i, populated);
255 }
256
257 return 0;
258
259err:
260 for_each_possible_cpu(tcpu) {
261 if (tcpu == cpu)
262 break;
263 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
264 page_end - page_start);
265 }
266 return err;
267}
268
269/**
270 * pcpu_post_map_flush - flush cache after mapping
271 * @chunk: pcpu_chunk the regions to be flushed belong to
272 * @page_start: page index of the first page to be flushed
273 * @page_end: page index of the last page to be flushed + 1
274 *
275 * Pages [@page_start,@page_end) of @chunk have been mapped. Flush
276 * cache.
277 *
278 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
279 * for the whole region.
280 */
281static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
282 int page_start, int page_end)
283{
284 flush_cache_vmap(
285 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
286 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
287}
288
289/**
290 * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
291 * @chunk: chunk of interest
292 * @off: offset to the area to populate
293 * @size: size of the area to populate in bytes
294 *
295 * For each cpu, populate and map pages [@page_start,@page_end) into
296 * @chunk. The area is cleared on return.
297 *
298 * CONTEXT:
299 * pcpu_alloc_mutex, does GFP_KERNEL allocation.
300 */
301static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
302{
303 int page_start = PFN_DOWN(off);
304 int page_end = PFN_UP(off + size);
305 int free_end = page_start, unmap_end = page_start;
306 struct page **pages;
307 unsigned long *populated;
308 unsigned int cpu;
309 int rs, re, rc;
310
311 /* quick path, check whether all pages are already there */
312 rs = page_start;
313 pcpu_next_pop(chunk, &rs, &re, page_end);
314 if (rs == page_start && re == page_end)
315 goto clear;
316
317 /* need to allocate and map pages, this chunk can't be immutable */
318 WARN_ON(chunk->immutable);
319
320 pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);
321 if (!pages)
322 return -ENOMEM;
323
324 /* alloc and map */
325 pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
326 rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);
327 if (rc)
328 goto err_free;
329 free_end = re;
330 }
331
332 pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
333 rc = pcpu_map_pages(chunk, pages, populated, rs, re);
334 if (rc)
335 goto err_unmap;
336 unmap_end = re;
337 }
338 pcpu_post_map_flush(chunk, page_start, page_end);
339
340 /* commit new bitmap */
341 bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
342clear:
343 for_each_possible_cpu(cpu)
344 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
345 return 0;
346
347err_unmap:
348 pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
349 pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
350 pcpu_unmap_pages(chunk, pages, populated, rs, re);
351 pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
352err_free:
353 pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
354 pcpu_free_pages(chunk, pages, populated, rs, re);
355 return rc;
356}
357
358/**
359 * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
360 * @chunk: chunk to depopulate
361 * @off: offset to the area to depopulate
362 * @size: size of the area to depopulate in bytes
363 *
364 * For each cpu, depopulate and unmap pages [@page_start,@page_end)
365 * from @chunk. If @flush is true, vcache is flushed before unmapping
366 * and tlb after.
367 *
368 * CONTEXT:
369 * pcpu_alloc_mutex.
370 */
371static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
372{
373 int page_start = PFN_DOWN(off);
374 int page_end = PFN_UP(off + size);
375 struct page **pages;
376 unsigned long *populated;
377 int rs, re;
378
379 /* quick path, check whether it's empty already */
380 rs = page_start;
381 pcpu_next_unpop(chunk, &rs, &re, page_end);
382 if (rs == page_start && re == page_end)
383 return;
384
385 /* immutable chunks can't be depopulated */
386 WARN_ON(chunk->immutable);
387
388 /*
389 * If control reaches here, there must have been at least one
390 * successful population attempt so the temp pages array must
391 * be available now.
392 */
393 pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);
394 BUG_ON(!pages);
395
396 /* unmap and free */
397 pcpu_pre_unmap_flush(chunk, page_start, page_end);
398
399 pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
400 pcpu_unmap_pages(chunk, pages, populated, rs, re);
401
402 /* no need to flush tlb, vmalloc will handle it lazily */
403
404 pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
405 pcpu_free_pages(chunk, pages, populated, rs, re);
406
407 /* commit new bitmap */
408 bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
409}
410
411static struct pcpu_chunk *pcpu_create_chunk(void)
412{
413 struct pcpu_chunk *chunk;
414 struct vm_struct **vms;
415
416 chunk = pcpu_alloc_chunk();
417 if (!chunk)
418 return NULL;
419
420 vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
421 pcpu_nr_groups, pcpu_atom_size);
422 if (!vms) {
423 pcpu_free_chunk(chunk);
424 return NULL;
425 }
426
427 chunk->data = vms;
428 chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
429 return chunk;
430}
431
432static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
433{
434 if (chunk && chunk->data)
435 pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
436 pcpu_free_chunk(chunk);
437}
438
439static struct page *pcpu_addr_to_page(void *addr)
440{
441 return vmalloc_to_page(addr);
442}
443
444static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
445{
446 /* no extra restriction */
447 return 0;
448}