blob: 7037bc73bfa42a5fd93294f27185a119387dbf17 [file] [log] [blame]
Tejun Heob0c97782010-04-09 18:57:01 +09001/*
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 Heobbddff02010-09-03 18:22:48 +020030#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
Tejun Heob0c97782010-04-09 18:57:01 +090031#error "contiguous percpu allocation is incompatible with paged first chunk"
32#endif
33
34#include <linux/log2.h>
35
36static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
37{
38 /* noop */
39 return 0;
40}
41
42static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
43{
44 /* nada */
45}
46
47static struct pcpu_chunk *pcpu_create_chunk(void)
48{
49 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
50 struct pcpu_chunk *chunk;
51 struct page *pages;
52 int i;
53
54 chunk = pcpu_alloc_chunk();
55 if (!chunk)
56 return NULL;
57
58 pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages));
59 if (!pages) {
60 pcpu_free_chunk(chunk);
61 return NULL;
62 }
63
64 for (i = 0; i < nr_pages; i++)
65 pcpu_set_page_chunk(nth_page(pages, i), chunk);
66
67 chunk->data = pages;
68 chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
69 return chunk;
70}
71
72static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
73{
74 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
75
76 if (chunk && chunk->data)
77 __free_pages(chunk->data, order_base_2(nr_pages));
78 pcpu_free_chunk(chunk);
79}
80
81static struct page *pcpu_addr_to_page(void *addr)
82{
83 return virt_to_page(addr);
84}
85
86static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
87{
88 size_t nr_pages, alloc_pages;
89
90 /* all units must be in a single group */
91 if (ai->nr_groups != 1) {
92 printk(KERN_CRIT "percpu: can't handle more than one groups\n");
93 return -EINVAL;
94 }
95
96 nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
97 alloc_pages = roundup_pow_of_two(nr_pages);
98
99 if (alloc_pages > nr_pages)
100 printk(KERN_WARNING "percpu: wasting %zu pages per chunk\n",
101 alloc_pages - nr_pages);
102
103 return 0;
104}