Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 1 | /* |
| 2 | * mm/percpu-km.c - kernel memory 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 allocated as a contiguous kernel memory using gfp |
| 10 | * allocation. This is to be used on nommu architectures. |
| 11 | * |
| 12 | * To use percpu-km, |
| 13 | * |
| 14 | * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig. |
| 15 | * |
| 16 | * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's |
| 17 | * not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work |
| 18 | * fine. |
| 19 | * |
| 20 | * - NUMA is not supported. When setting up the first chunk, |
| 21 | * @cpu_distance_fn should be NULL or report all CPUs to be nearer |
| 22 | * than or at LOCAL_DISTANCE. |
| 23 | * |
| 24 | * - It's best if the chunk size is power of two multiple of |
| 25 | * PAGE_SIZE. Because each chunk is allocated as a contiguous |
| 26 | * kernel memory block using alloc_pages(), memory will be wasted if |
| 27 | * chunk size is not aligned. percpu-km code will whine about it. |
| 28 | */ |
| 29 | |
Tejun Heo | bbddff0 | 2010-09-03 18:22:48 +0200 | [diff] [blame] | 30 | #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 31 | #error "contiguous percpu allocation is incompatible with paged first chunk" |
| 32 | #endif |
| 33 | |
| 34 | #include <linux/log2.h> |
| 35 | |
Tejun Heo | a93ace4 | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 36 | static int pcpu_populate_chunk(struct pcpu_chunk *chunk, |
| 37 | int page_start, int page_end) |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 38 | { |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 39 | return 0; |
| 40 | } |
| 41 | |
Tejun Heo | a93ace4 | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 42 | static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, |
| 43 | int page_start, int page_end) |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 44 | { |
| 45 | /* nada */ |
| 46 | } |
| 47 | |
| 48 | static struct pcpu_chunk *pcpu_create_chunk(void) |
| 49 | { |
| 50 | const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; |
| 51 | struct pcpu_chunk *chunk; |
| 52 | struct page *pages; |
| 53 | int i; |
| 54 | |
| 55 | chunk = pcpu_alloc_chunk(); |
| 56 | if (!chunk) |
| 57 | return NULL; |
| 58 | |
| 59 | pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages)); |
| 60 | if (!pages) { |
| 61 | pcpu_free_chunk(chunk); |
| 62 | return NULL; |
| 63 | } |
| 64 | |
| 65 | for (i = 0; i < nr_pages; i++) |
| 66 | pcpu_set_page_chunk(nth_page(pages, i), chunk); |
| 67 | |
| 68 | chunk->data = pages; |
| 69 | chunk->base_addr = page_address(pages) - pcpu_group_offsets[0]; |
Tejun Heo | a63d4ac | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 70 | |
Tejun Heo | b38d08f | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 71 | spin_lock_irq(&pcpu_lock); |
Tejun Heo | b539b87 | 2014-09-02 14:46:05 -0400 | [diff] [blame] | 72 | pcpu_chunk_populated(chunk, 0, nr_pages); |
Tejun Heo | b38d08f | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 73 | spin_unlock_irq(&pcpu_lock); |
Tejun Heo | a63d4ac | 2014-09-02 14:46:02 -0400 | [diff] [blame] | 74 | |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 75 | return chunk; |
| 76 | } |
| 77 | |
| 78 | static void pcpu_destroy_chunk(struct pcpu_chunk *chunk) |
| 79 | { |
| 80 | const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; |
| 81 | |
| 82 | if (chunk && chunk->data) |
| 83 | __free_pages(chunk->data, order_base_2(nr_pages)); |
| 84 | pcpu_free_chunk(chunk); |
| 85 | } |
| 86 | |
| 87 | static struct page *pcpu_addr_to_page(void *addr) |
| 88 | { |
| 89 | return virt_to_page(addr); |
| 90 | } |
| 91 | |
| 92 | static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai) |
| 93 | { |
| 94 | size_t nr_pages, alloc_pages; |
| 95 | |
| 96 | /* all units must be in a single group */ |
| 97 | if (ai->nr_groups != 1) { |
Joe Perches | 870d4b1 | 2016-03-17 14:19:53 -0700 | [diff] [blame] | 98 | pr_crit("can't handle more than one group\n"); |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 99 | return -EINVAL; |
| 100 | } |
| 101 | |
| 102 | nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT; |
| 103 | alloc_pages = roundup_pow_of_two(nr_pages); |
| 104 | |
| 105 | if (alloc_pages > nr_pages) |
Joe Perches | 870d4b1 | 2016-03-17 14:19:53 -0700 | [diff] [blame] | 106 | pr_warn("wasting %zu pages per chunk\n", |
Joe Perches | 1170532 | 2016-03-17 14:19:50 -0700 | [diff] [blame] | 107 | alloc_pages - nr_pages); |
Tejun Heo | b0c9778 | 2010-04-09 18:57:01 +0900 | [diff] [blame] | 108 | |
| 109 | return 0; |
| 110 | } |