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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
29#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
30#error "contiguous percpu allocation is incompatible with paged first chunk"
31#endif
32
33#include <linux/log2.h>
34
35static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
36 int page_start, int page_end, gfp_t gfp)
37{
38 return 0;
39}
40
41static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
42 int page_start, int page_end)
43{
44 /* nada */
45}
46
47static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp)
48{
49 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
50 struct pcpu_chunk *chunk;
51 struct page *pages;
52 unsigned long flags;
53 int i;
54
55 chunk = pcpu_alloc_chunk(gfp);
56 if (!chunk)
57 return NULL;
58
59 pages = alloc_pages(gfp, 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);
70
71 spin_lock_irqsave(&pcpu_lock, flags);
72 pcpu_chunk_populated(chunk, 0, nr_pages);
73 spin_unlock_irqrestore(&pcpu_lock, flags);
74
75 pcpu_stats_chunk_alloc();
76 trace_percpu_create_chunk(chunk->base_addr);
77
78 return chunk;
79}
80
81static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
82{
83 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
84
85 if (!chunk)
86 return;
87
88 pcpu_stats_chunk_dealloc();
89 trace_percpu_destroy_chunk(chunk->base_addr);
90
91 if (chunk->data)
92 __free_pages(chunk->data, order_base_2(nr_pages));
93 pcpu_free_chunk(chunk);
94}
95
96static struct page *pcpu_addr_to_page(void *addr)
97{
98 return virt_to_page(addr);
99}
100
101static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
102{
103 size_t nr_pages, alloc_pages;
104
105 /* all units must be in a single group */
106 if (ai->nr_groups != 1) {
107 pr_crit("can't handle more than one group\n");
108 return -EINVAL;
109 }
110
111 nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
112 alloc_pages = roundup_pow_of_two(nr_pages);
113
114 if (alloc_pages > nr_pages)
115 pr_warn("wasting %zu pages per chunk\n",
116 alloc_pages - nr_pages);
117
118 return 0;
119}
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
36static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
37{
38 unsigned int cpu;
39
40 for_each_possible_cpu(cpu)
41 memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
42
43 return 0;
44}
45
46static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
47{
48 /* nada */
49}
50
51static struct pcpu_chunk *pcpu_create_chunk(void)
52{
53 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
54 struct pcpu_chunk *chunk;
55 struct page *pages;
56 int i;
57
58 chunk = pcpu_alloc_chunk();
59 if (!chunk)
60 return NULL;
61
62 pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages));
63 if (!pages) {
64 pcpu_free_chunk(chunk);
65 return NULL;
66 }
67
68 for (i = 0; i < nr_pages; i++)
69 pcpu_set_page_chunk(nth_page(pages, i), chunk);
70
71 chunk->data = pages;
72 chunk->base_addr = page_address(pages) - pcpu_group_offsets[0];
73 return chunk;
74}
75
76static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
77{
78 const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT;
79
80 if (chunk && chunk->data)
81 __free_pages(chunk->data, order_base_2(nr_pages));
82 pcpu_free_chunk(chunk);
83}
84
85static struct page *pcpu_addr_to_page(void *addr)
86{
87 return virt_to_page(addr);
88}
89
90static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
91{
92 size_t nr_pages, alloc_pages;
93
94 /* all units must be in a single group */
95 if (ai->nr_groups != 1) {
96 printk(KERN_CRIT "percpu: can't handle more than one groups\n");
97 return -EINVAL;
98 }
99
100 nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT;
101 alloc_pages = roundup_pow_of_two(nr_pages);
102
103 if (alloc_pages > nr_pages)
104 printk(KERN_WARNING "percpu: wasting %zu pages per chunk\n",
105 alloc_pages - nr_pages);
106
107 return 0;
108}