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TOMOYO Linux Cross Reference
Linux/mm/percpu-vm.c

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  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 
 13 static 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  */
 41 static 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  */
 77 static 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  */
106 static 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, tcpu;
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                                 goto err;
121                 }
122         }
123         return 0;
124 
125 err:
126         while (--i >= page_start)
127                 __free_page(pages[pcpu_page_idx(cpu, i)]);
128 
129         for_each_possible_cpu(tcpu) {
130                 if (tcpu == cpu)
131                         break;
132                 for (i = page_start; i < page_end; i++)
133                         __free_page(pages[pcpu_page_idx(tcpu, i)]);
134         }
135         return -ENOMEM;
136 }
137 
138 /**
139  * pcpu_pre_unmap_flush - flush cache prior to unmapping
140  * @chunk: chunk the regions to be flushed belongs to
141  * @page_start: page index of the first page to be flushed
142  * @page_end: page index of the last page to be flushed + 1
143  *
144  * Pages in [@page_start,@page_end) of @chunk are about to be
145  * unmapped.  Flush cache.  As each flushing trial can be very
146  * expensive, issue flush on the whole region at once rather than
147  * doing it for each cpu.  This could be an overkill but is more
148  * scalable.
149  */
150 static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
151                                  int page_start, int page_end)
152 {
153         flush_cache_vunmap(
154                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
155                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
156 }
157 
158 static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
159 {
160         unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
161 }
162 
163 /**
164  * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
165  * @chunk: chunk of interest
166  * @pages: pages array which can be used to pass information to free
167  * @populated: populated bitmap
168  * @page_start: page index of the first page to unmap
169  * @page_end: page index of the last page to unmap + 1
170  *
171  * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
172  * Corresponding elements in @pages were cleared by the caller and can
173  * be used to carry information to pcpu_free_pages() which will be
174  * called after all unmaps are finished.  The caller should call
175  * proper pre/post flush functions.
176  */
177 static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
178                              struct page **pages, unsigned long *populated,
179                              int page_start, int page_end)
180 {
181         unsigned int cpu;
182         int i;
183 
184         for_each_possible_cpu(cpu) {
185                 for (i = page_start; i < page_end; i++) {
186                         struct page *page;
187 
188                         page = pcpu_chunk_page(chunk, cpu, i);
189                         WARN_ON(!page);
190                         pages[pcpu_page_idx(cpu, i)] = page;
191                 }
192                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
193                                    page_end - page_start);
194         }
195 
196         bitmap_clear(populated, page_start, page_end - page_start);
197 }
198 
199 /**
200  * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
201  * @chunk: pcpu_chunk the regions to be flushed belong to
202  * @page_start: page index of the first page to be flushed
203  * @page_end: page index of the last page to be flushed + 1
204  *
205  * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
206  * TLB for the regions.  This can be skipped if the area is to be
207  * returned to vmalloc as vmalloc will handle TLB flushing lazily.
208  *
209  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
210  * for the whole region.
211  */
212 static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
213                                       int page_start, int page_end)
214 {
215         flush_tlb_kernel_range(
216                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
217                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
218 }
219 
220 static int __pcpu_map_pages(unsigned long addr, struct page **pages,
221                             int nr_pages)
222 {
223         return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
224                                         PAGE_KERNEL, pages);
225 }
226 
227 /**
228  * pcpu_map_pages - map pages into a pcpu_chunk
229  * @chunk: chunk of interest
230  * @pages: pages array containing pages to be mapped
231  * @populated: populated bitmap
232  * @page_start: page index of the first page to map
233  * @page_end: page index of the last page to map + 1
234  *
235  * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
236  * caller is responsible for calling pcpu_post_map_flush() after all
237  * mappings are complete.
238  *
239  * This function is responsible for setting corresponding bits in
240  * @chunk->populated bitmap and whatever is necessary for reverse
241  * lookup (addr -> chunk).
242  */
243 static int pcpu_map_pages(struct pcpu_chunk *chunk,
244                           struct page **pages, unsigned long *populated,
245                           int page_start, int page_end)
246 {
247         unsigned int cpu, tcpu;
248         int i, err;
249 
250         for_each_possible_cpu(cpu) {
251                 err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
252                                        &pages[pcpu_page_idx(cpu, page_start)],
253                                        page_end - page_start);
254                 if (err < 0)
255                         goto err;
256         }
257 
258         /* mapping successful, link chunk and mark populated */
259         for (i = page_start; i < page_end; i++) {
260                 for_each_possible_cpu(cpu)
261                         pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
262                                             chunk);
263                 __set_bit(i, populated);
264         }
265 
266         return 0;
267 
268 err:
269         for_each_possible_cpu(tcpu) {
270                 if (tcpu == cpu)
271                         break;
272                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
273                                    page_end - page_start);
274         }
275         pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
276         return err;
277 }
278 
279 /**
280  * pcpu_post_map_flush - flush cache after mapping
281  * @chunk: pcpu_chunk the regions to be flushed belong to
282  * @page_start: page index of the first page to be flushed
283  * @page_end: page index of the last page to be flushed + 1
284  *
285  * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
286  * cache.
287  *
288  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
289  * for the whole region.
290  */
291 static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
292                                 int page_start, int page_end)
293 {
294         flush_cache_vmap(
295                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
296                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
297 }
298 
299 /**
300  * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
301  * @chunk: chunk of interest
302  * @off: offset to the area to populate
303  * @size: size of the area to populate in bytes
304  *
305  * For each cpu, populate and map pages [@page_start,@page_end) into
306  * @chunk.  The area is cleared on return.
307  *
308  * CONTEXT:
309  * pcpu_alloc_mutex, does GFP_KERNEL allocation.
310  */
311 static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
312 {
313         int page_start = PFN_DOWN(off);
314         int page_end = PFN_UP(off + size);
315         int free_end = page_start, unmap_end = page_start;
316         struct page **pages;
317         unsigned long *populated;
318         unsigned int cpu;
319         int rs, re, rc;
320 
321         /* quick path, check whether all pages are already there */
322         rs = page_start;
323         pcpu_next_pop(chunk, &rs, &re, page_end);
324         if (rs == page_start && re == page_end)
325                 goto clear;
326 
327         /* need to allocate and map pages, this chunk can't be immutable */
328         WARN_ON(chunk->immutable);
329 
330         pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);
331         if (!pages)
332                 return -ENOMEM;
333 
334         /* alloc and map */
335         pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
336                 rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);
337                 if (rc)
338                         goto err_free;
339                 free_end = re;
340         }
341 
342         pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
343                 rc = pcpu_map_pages(chunk, pages, populated, rs, re);
344                 if (rc)
345                         goto err_unmap;
346                 unmap_end = re;
347         }
348         pcpu_post_map_flush(chunk, page_start, page_end);
349 
350         /* commit new bitmap */
351         bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
352 clear:
353         for_each_possible_cpu(cpu)
354                 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
355         return 0;
356 
357 err_unmap:
358         pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
359         pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
360                 pcpu_unmap_pages(chunk, pages, populated, rs, re);
361         pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
362 err_free:
363         pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
364                 pcpu_free_pages(chunk, pages, populated, rs, re);
365         return rc;
366 }
367 
368 /**
369  * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
370  * @chunk: chunk to depopulate
371  * @off: offset to the area to depopulate
372  * @size: size of the area to depopulate in bytes
373  *
374  * For each cpu, depopulate and unmap pages [@page_start,@page_end)
375  * from @chunk.  If @flush is true, vcache is flushed before unmapping
376  * and tlb after.
377  *
378  * CONTEXT:
379  * pcpu_alloc_mutex.
380  */
381 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
382 {
383         int page_start = PFN_DOWN(off);
384         int page_end = PFN_UP(off + size);
385         struct page **pages;
386         unsigned long *populated;
387         int rs, re;
388 
389         /* quick path, check whether it's empty already */
390         rs = page_start;
391         pcpu_next_unpop(chunk, &rs, &re, page_end);
392         if (rs == page_start && re == page_end)
393                 return;
394 
395         /* immutable chunks can't be depopulated */
396         WARN_ON(chunk->immutable);
397 
398         /*
399          * If control reaches here, there must have been at least one
400          * successful population attempt so the temp pages array must
401          * be available now.
402          */
403         pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);
404         BUG_ON(!pages);
405 
406         /* unmap and free */
407         pcpu_pre_unmap_flush(chunk, page_start, page_end);
408 
409         pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
410                 pcpu_unmap_pages(chunk, pages, populated, rs, re);
411 
412         /* no need to flush tlb, vmalloc will handle it lazily */
413 
414         pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
415                 pcpu_free_pages(chunk, pages, populated, rs, re);
416 
417         /* commit new bitmap */
418         bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
419 }
420 
421 static struct pcpu_chunk *pcpu_create_chunk(void)
422 {
423         struct pcpu_chunk *chunk;
424         struct vm_struct **vms;
425 
426         chunk = pcpu_alloc_chunk();
427         if (!chunk)
428                 return NULL;
429 
430         vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
431                                 pcpu_nr_groups, pcpu_atom_size);
432         if (!vms) {
433                 pcpu_free_chunk(chunk);
434                 return NULL;
435         }
436 
437         chunk->data = vms;
438         chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
439         return chunk;
440 }
441 
442 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
443 {
444         if (chunk && chunk->data)
445                 pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
446         pcpu_free_chunk(chunk);
447 }
448 
449 static struct page *pcpu_addr_to_page(void *addr)
450 {
451         return vmalloc_to_page(addr);
452 }
453 
454 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
455 {
456         /* no extra restriction */
457         return 0;
458 }
459 

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