mm/percpu-vm.c

   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 - get temp pages array
  24  * @chunk: chunk of interest
  25  *
  26  * Returns pointer to array of pointers to struct page which can be indexed
  27  * with pcpu_page_idx().  Note that there is only one array and accesses
  28  * should be serialized by pcpu_alloc_mutex.
  29  *
  30  * RETURNS:
  31  * Pointer to temp pages array on success.
  32  */
  33 static struct page **pcpu_get_pages(struct pcpu_chunk *chunk_alloc)
  34 {
  35         static struct page **pages;
  36         size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
  37
  38         lockdep_assert_held(&pcpu_alloc_mutex);
  39
  40         if (!pages)
  41                 pages = pcpu_mem_zalloc(pages_size);
  42         return pages;
  43 }
  44
  45 /**
  46  * pcpu_free_pages - free pages which were allocated for @chunk
  47  * @chunk: chunk pages were allocated for
  48  * @pages: array of pages to be freed, indexed by pcpu_page_idx()
  49  * @page_start: page index of the first page to be freed
  50  * @page_end: page index of the last page to be freed + 1
  51  *
  52  * Free pages [@page_start and @page_end) in @pages for all units.
  53  * The pages were allocated for @chunk.
  54  */
  55 static void pcpu_free_pages(struct pcpu_chunk *chunk,
  56                             struct page **pages, int page_start, int page_end)
  57 {
  58         unsigned int cpu;
  59         int i;
  60
  61         for_each_possible_cpu(cpu) {
  62                 for (i = page_start; i < page_end; i++) {
  63                         struct page *page = pages[pcpu_page_idx(cpu, i)];
  64
  65                         if (page)
  66                                 __free_page(page);
  67                 }
  68         }
  69 }
  70
  71 /**
  72  * pcpu_alloc_pages - allocates pages for @chunk
  73  * @chunk: target chunk
  74  * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
  75  * @page_start: page index of the first page to be allocated
  76  * @page_end: page index of the last page to be allocated + 1
  77  *
  78  * Allocate pages [@page_start,@page_end) into @pages for all units.
  79  * The allocation is for @chunk.  Percpu core doesn't care about the
  80  * content of @pages and will pass it verbatim to pcpu_map_pages().
  81  */
  82 static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
  83                             struct page **pages, int page_start, int page_end)
  84 {
  85         const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
  86         unsigned int cpu, tcpu;
  87         int i;
  88
  89         for_each_possible_cpu(cpu) {
  90                 for (i = page_start; i < page_end; i++) {
  91                         struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
  92
  93                         *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
  94                         if (!*pagep)
  95                                 goto err;
  96                 }
  97         }
  98         return 0;
  99
 100 err:
 101         while (--i >= page_start)
 102                 __free_page(pages[pcpu_page_idx(cpu, i)]);
 103
 104         for_each_possible_cpu(tcpu) {
 105                 if (tcpu == cpu)
 106                         break;
 107                 for (i = page_start; i < page_end; i++)
 108                         __free_page(pages[pcpu_page_idx(tcpu, i)]);
 109         }
 110         return -ENOMEM;
 111 }
 112
 113 /**
 114  * pcpu_pre_unmap_flush - flush cache prior to unmapping
 115  * @chunk: chunk the regions to be flushed belongs to
 116  * @page_start: page index of the first page to be flushed
 117  * @page_end: page index of the last page to be flushed + 1
 118  *
 119  * Pages in [@page_start,@page_end) of @chunk are about to be
 120  * unmapped.  Flush cache.  As each flushing trial can be very
 121  * expensive, issue flush on the whole region at once rather than
 122  * doing it for each cpu.  This could be an overkill but is more
 123  * scalable.
 124  */
 125 static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
 126                                  int page_start, int page_end)
 127 {
 128         flush_cache_vunmap(
 129                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
 130                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
 131 }
 132
 133 static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
 134 {
 135         unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
 136 }
 137
 138 /**
 139  * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
 140  * @chunk: chunk of interest
 141  * @pages: pages array which can be used to pass information to free
 142  * @page_start: page index of the first page to unmap
 143  * @page_end: page index of the last page to unmap + 1
 144  *
 145  * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
 146  * Corresponding elements in @pages were cleared by the caller and can
 147  * be used to carry information to pcpu_free_pages() which will be
 148  * called after all unmaps are finished.  The caller should call
 149  * proper pre/post flush functions.
 150  */
 151 static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
 152                              struct page **pages, int page_start, int page_end)
 153 {
 154         unsigned int cpu;
 155         int i;
 156
 157         for_each_possible_cpu(cpu) {
 158                 for (i = page_start; i < page_end; i++) {
 159                         struct page *page;
 160
 161                         page = pcpu_chunk_page(chunk, cpu, i);
 162                         WARN_ON(!page);
 163                         pages[pcpu_page_idx(cpu, i)] = page;
 164                 }
 165                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
 166                                    page_end - page_start);
 167         }
 168 }
 169
 170 /**
 171  * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
 172  * @chunk: pcpu_chunk the regions to be flushed belong to
 173  * @page_start: page index of the first page to be flushed
 174  * @page_end: page index of the last page to be flushed + 1
 175  *
 176  * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
 177  * TLB for the regions.  This can be skipped if the area is to be
 178  * returned to vmalloc as vmalloc will handle TLB flushing lazily.
 179  *
 180  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
 181  * for the whole region.
 182  */
 183 static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
 184                                       int page_start, int page_end)
 185 {
 186         flush_tlb_kernel_range(
 187                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
 188                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
 189 }
 190
 191 static int __pcpu_map_pages(unsigned long addr, struct page **pages,
 192                             int nr_pages)
 193 {
 194         return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
 195                                         PAGE_KERNEL, pages);
 196 }
 197
 198 /**
 199  * pcpu_map_pages - map pages into a pcpu_chunk
 200  * @chunk: chunk of interest
 201  * @pages: pages array containing pages to be mapped
 202  * @page_start: page index of the first page to map
 203  * @page_end: page index of the last page to map + 1
 204  *
 205  * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
 206  * caller is responsible for calling pcpu_post_map_flush() after all
 207  * mappings are complete.
 208  *
 209  * This function is responsible for setting up whatever is necessary for
 210  * reverse lookup (addr -> chunk).
 211  */
 212 static int pcpu_map_pages(struct pcpu_chunk *chunk,
 213                           struct page **pages, int page_start, int page_end)
 214 {
 215         unsigned int cpu, tcpu;
 216         int i, err;
 217
 218         for_each_possible_cpu(cpu) {
 219                 err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
 220                                        &pages[pcpu_page_idx(cpu, page_start)],
 221                                        page_end - page_start);
 222                 if (err < 0)
 223                         goto err;
 224
 225                 for (i = page_start; i < page_end; i++)
 226                         pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
 227                                             chunk);
 228         }
 229         return 0;
 230 err:
 231         for_each_possible_cpu(tcpu) {
 232                 if (tcpu == cpu)
 233                         break;
 234                 __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
 235                                    page_end - page_start);
 236         }
 237         pcpu_post_unmap_tlb_flush(chunk, page_start, page_end);
 238         return err;
 239 }
 240
 241 /**
 242  * pcpu_post_map_flush - flush cache after mapping
 243  * @chunk: pcpu_chunk the regions to be flushed belong to
 244  * @page_start: page index of the first page to be flushed
 245  * @page_end: page index of the last page to be flushed + 1
 246  *
 247  * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
 248  * cache.
 249  *
 250  * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
 251  * for the whole region.
 252  */
 253 static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
 254                                 int page_start, int page_end)
 255 {
 256         flush_cache_vmap(
 257                 pcpu_chunk_addr(chunk, pcpu_low_unit_cpu, page_start),
 258                 pcpu_chunk_addr(chunk, pcpu_high_unit_cpu, page_end));
 259 }
 260
 261 /**
 262  * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
 263  * @chunk: chunk of interest
 264  * @page_start: the start page
 265  * @page_end: the end page
 266  *
 267  * For each cpu, populate and map pages [@page_start,@page_end) into
 268  * @chunk.
 269  *
 270  * CONTEXT:
 271  * pcpu_alloc_mutex, does GFP_KERNEL allocation.
 272  */
 273 static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
 274                                int page_start, int page_end)
 275 {
 276         struct page **pages;
 277
 278         pages = pcpu_get_pages(chunk);
 279         if (!pages)
 280                 return -ENOMEM;
 281
 282         if (pcpu_alloc_pages(chunk, pages, page_start, page_end))
 283                 return -ENOMEM;
 284
 285         if (pcpu_map_pages(chunk, pages, page_start, page_end)) {
 286                 pcpu_free_pages(chunk, pages, page_start, page_end);
 287                 return -ENOMEM;
 288         }
 289         pcpu_post_map_flush(chunk, page_start, page_end);
 290
 291         return 0;
 292 }
 293
 294 /**
 295  * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
 296  * @chunk: chunk to depopulate
 297  * @page_start: the start page
 298  * @page_end: the end page
 299  *
 300  * For each cpu, depopulate and unmap pages [@page_start,@page_end)
 301  * from @chunk.
 302  *
 303  * CONTEXT:
 304  * pcpu_alloc_mutex.
 305  */
 306 static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
 307                                   int page_start, int page_end)
 308 {
 309         struct page **pages;
 310
 311         /*
 312          * If control reaches here, there must have been at least one
 313          * successful population attempt so the temp pages array must
 314          * be available now.
 315          */
 316         pages = pcpu_get_pages(chunk);
 317         BUG_ON(!pages);
 318
 319         /* unmap and free */
 320         pcpu_pre_unmap_flush(chunk, page_start, page_end);
 321
 322         pcpu_unmap_pages(chunk, pages, page_start, page_end);
 323
 324         /* no need to flush tlb, vmalloc will handle it lazily */
 325
 326         pcpu_free_pages(chunk, pages, page_start, page_end);
 327 }
 328
 329 static struct pcpu_chunk *pcpu_create_chunk(void)
 330 {
 331         struct pcpu_chunk *chunk;
 332         struct vm_struct **vms;
 333
 334         chunk = pcpu_alloc_chunk();
 335         if (!chunk)
 336                 return NULL;
 337
 338         vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
 339                                 pcpu_nr_groups, pcpu_atom_size);
 340         if (!vms) {
 341                 pcpu_free_chunk(chunk);
 342                 return NULL;
 343         }
 344
 345         chunk->data = vms;
 346         chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
 347         return chunk;
 348 }
 349
 350 static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
 351 {
 352         if (chunk && chunk->data)
 353                 pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
 354         pcpu_free_chunk(chunk);
 355 }
 356
 357 static struct page *pcpu_addr_to_page(void *addr)
 358 {
 359         return vmalloc_to_page(addr);
 360 }
 361
 362 static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
 363 {
 364         /* no extra restriction */
 365         return 0;
 366 }