blob: d66911ff42d9618dd73107548e4f99b06d2f98ef
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 | |
30 | #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) |
31 | #error "contiguous percpu allocation is incompatible with paged first chunk" |
32 | #endif |
33 | |
34 | #include <linux/log2.h> |
35 | |
36 | static int pcpu_populate_chunk(struct pcpu_chunk *chunk, |
37 | int page_start, int page_end) |
38 | { |
39 | return 0; |
40 | } |
41 | |
42 | static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, |
43 | int page_start, int page_end) |
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]; |
70 | |
71 | spin_lock_irq(&pcpu_lock); |
72 | pcpu_chunk_populated(chunk, 0, nr_pages); |
73 | spin_unlock_irq(&pcpu_lock); |
74 | |
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) { |
98 | pr_crit("can't handle more than one group\n"); |
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) |
106 | pr_warn("wasting %zu pages per chunk\n", |
107 | alloc_pages - nr_pages); |
108 | |
109 | return 0; |
110 | } |
111 |