percpu-km.c 3.0 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120
  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * mm/percpu-km.c - kernel memory based chunk allocation
  4. *
  5. * Copyright (C) 2010 SUSE Linux Products GmbH
  6. * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
  7. *
  8. * Chunks are allocated as a contiguous kernel memory using gfp
  9. * allocation. This is to be used on nommu architectures.
  10. *
  11. * To use percpu-km,
  12. *
  13. * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig.
  14. *
  15. * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's
  16. * not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work
  17. * fine.
  18. *
  19. * - NUMA is not supported. When setting up the first chunk,
  20. * @cpu_distance_fn should be NULL or report all CPUs to be nearer
  21. * than or at LOCAL_DISTANCE.
  22. *
  23. * - It's best if the chunk size is power of two multiple of
  24. * PAGE_SIZE. Because each chunk is allocated as a contiguous
  25. * kernel memory block using alloc_pages(), memory will be wasted if
  26. * chunk size is not aligned. percpu-km code will whine about it.
  27. */
  28. #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
  29. #error "contiguous percpu allocation is incompatible with paged first chunk"
  30. #endif
  31. #include <linux/log2.h>
  32. static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
  33. int page_start, int page_end, gfp_t gfp)
  34. {
  35. return 0;
  36. }
  37. static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
  38. int page_start, int page_end)
  39. {
  40. /* nada */
  41. }
  42. static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
  43. gfp_t gfp)
  44. {
  45. const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
  46. struct pcpu_chunk *chunk;
  47. struct page *pages;
  48. unsigned long flags;
  49. int i;
  50. chunk = pcpu_alloc_chunk(type, gfp);
  51. if (!chunk)
  52. return NULL;
  53. pages = alloc_pages(gfp, order_base_2(nr_pages));
  54. if (!pages) {
  55. pcpu_free_chunk(chunk);
  56. return NULL;
  57. }
  58. for (i = 0; i < nr_pages; i++)
  59. pcpu_set_page_chunk(nth_page(pages, i), chunk);
  60. chunk->data = pages;
  61. chunk->base_addr = page_address(pages);
  62. spin_lock_irqsave(&pcpu_lock, flags);
  63. pcpu_chunk_populated(chunk, 0, nr_pages);
  64. spin_unlock_irqrestore(&pcpu_lock, flags);
  65. pcpu_stats_chunk_alloc();
  66. trace_percpu_create_chunk(chunk->base_addr);
  67. return chunk;
  68. }
  69. static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
  70. {
  71. const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
  72. if (!chunk)
  73. return;
  74. pcpu_stats_chunk_dealloc();
  75. trace_percpu_destroy_chunk(chunk->base_addr);
  76. if (chunk->data)
  77. __free_pages(chunk->data, order_base_2(nr_pages));
  78. pcpu_free_chunk(chunk);
  79. }
  80. static struct page *pcpu_addr_to_page(void *addr)
  81. {
  82. return virt_to_page(addr);
  83. }
  84. static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
  85. {
  86. size_t nr_pages, alloc_pages;
  87. /* all units must be in a single group */
  88. if (ai->nr_groups != 1) {
  89. pr_crit("can't handle more than one group\n");
  90. return -EINVAL;
  91. }
  92. nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
  93. alloc_pages = roundup_pow_of_two(nr_pages);
  94. if (alloc_pages > nr_pages)
  95. pr_warn("wasting %zu pages per chunk\n",
  96. alloc_pages - nr_pages);
  97. return 0;
  98. }