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[mirror_ubuntu-bionic-kernel.git] / mm / kmemcheck.c
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b1eeab67 1#include <linux/gfp.h>
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2#include <linux/mm_types.h>
3#include <linux/mm.h>
4#include <linux/slab.h>
07f361b2 5#include "slab.h"
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6#include <linux/kmemcheck.h>
7
b1eeab67 8void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
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9{
10 struct page *shadow;
11 int pages;
12 int i;
13
14 pages = 1 << order;
15
16 /*
17 * With kmemcheck enabled, we need to allocate a memory area for the
18 * shadow bits as well.
19 */
b1eeab67 20 shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
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21 if (!shadow) {
22 if (printk_ratelimit())
1170532b 23 pr_err("kmemcheck: failed to allocate shadow bitmap\n");
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24 return;
25 }
26
27 for(i = 0; i < pages; ++i)
28 page[i].shadow = page_address(&shadow[i]);
29
30 /*
31 * Mark it as non-present for the MMU so that our accesses to
32 * this memory will trigger a page fault and let us analyze
33 * the memory accesses.
34 */
35 kmemcheck_hide_pages(page, pages);
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36}
37
b1eeab67 38void kmemcheck_free_shadow(struct page *page, int order)
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39{
40 struct page *shadow;
41 int pages;
42 int i;
43
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44 if (!kmemcheck_page_is_tracked(page))
45 return;
46
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47 pages = 1 << order;
48
49 kmemcheck_show_pages(page, pages);
50
51 shadow = virt_to_page(page[0].shadow);
52
53 for(i = 0; i < pages; ++i)
54 page[i].shadow = NULL;
55
56 __free_pages(shadow, order);
57}
58
59void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
60 size_t size)
61{
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62 if (unlikely(!object)) /* Skip object if allocation failed */
63 return;
64
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65 /*
66 * Has already been memset(), which initializes the shadow for us
67 * as well.
68 */
69 if (gfpflags & __GFP_ZERO)
70 return;
71
72 /* No need to initialize the shadow of a non-tracked slab. */
73 if (s->flags & SLAB_NOTRACK)
74 return;
75
76 if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
77 /*
78 * Allow notracked objects to be allocated from
79 * tracked caches. Note however that these objects
80 * will still get page faults on access, they just
81 * won't ever be flagged as uninitialized. If page
82 * faults are not acceptable, the slab cache itself
83 * should be marked NOTRACK.
84 */
85 kmemcheck_mark_initialized(object, size);
86 } else if (!s->ctor) {
87 /*
88 * New objects should be marked uninitialized before
89 * they're returned to the called.
90 */
91 kmemcheck_mark_uninitialized(object, size);
92 }
93}
94
95void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
96{
97 /* TODO: RCU freeing is unsupported for now; hide false positives. */
98 if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
99 kmemcheck_mark_freed(object, size);
100}
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101
102void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
103 gfp_t gfpflags)
104{
105 int pages;
106
107 if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
108 return;
109
110 pages = 1 << order;
111
112 /*
113 * NOTE: We choose to track GFP_ZERO pages too; in fact, they
114 * can become uninitialized by copying uninitialized memory
115 * into them.
116 */
117
118 /* XXX: Can use zone->node for node? */
119 kmemcheck_alloc_shadow(page, order, gfpflags, -1);
120
121 if (gfpflags & __GFP_ZERO)
122 kmemcheck_mark_initialized_pages(page, pages);
123 else
124 kmemcheck_mark_uninitialized_pages(page, pages);
125}