Root/mm/kmemcheck.c

1#include <linux/gfp.h>
2#include <linux/mm_types.h>
3#include <linux/mm.h>
4#include <linux/slab.h>
5#include <linux/kmemcheck.h>
6
7void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
8{
9    struct page *shadow;
10    int pages;
11    int i;
12
13    pages = 1 << order;
14
15    /*
16     * With kmemcheck enabled, we need to allocate a memory area for the
17     * shadow bits as well.
18     */
19    shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
20    if (!shadow) {
21        if (printk_ratelimit())
22            printk(KERN_ERR "kmemcheck: failed to allocate "
23                "shadow bitmap\n");
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);
36}
37
38void kmemcheck_free_shadow(struct page *page, int order)
39{
40    struct page *shadow;
41    int pages;
42    int i;
43
44    if (!kmemcheck_page_is_tracked(page))
45        return;
46
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{
62    /*
63     * Has already been memset(), which initializes the shadow for us
64     * as well.
65     */
66    if (gfpflags & __GFP_ZERO)
67        return;
68
69    /* No need to initialize the shadow of a non-tracked slab. */
70    if (s->flags & SLAB_NOTRACK)
71        return;
72
73    if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
74        /*
75         * Allow notracked objects to be allocated from
76         * tracked caches. Note however that these objects
77         * will still get page faults on access, they just
78         * won't ever be flagged as uninitialized. If page
79         * faults are not acceptable, the slab cache itself
80         * should be marked NOTRACK.
81         */
82        kmemcheck_mark_initialized(object, size);
83    } else if (!s->ctor) {
84        /*
85         * New objects should be marked uninitialized before
86         * they're returned to the called.
87         */
88        kmemcheck_mark_uninitialized(object, size);
89    }
90}
91
92void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
93{
94    /* TODO: RCU freeing is unsupported for now; hide false positives. */
95    if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
96        kmemcheck_mark_freed(object, size);
97}
98
99void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
100                   gfp_t gfpflags)
101{
102    int pages;
103
104    if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
105        return;
106
107    pages = 1 << order;
108
109    /*
110     * NOTE: We choose to track GFP_ZERO pages too; in fact, they
111     * can become uninitialized by copying uninitialized memory
112     * into them.
113     */
114
115    /* XXX: Can use zone->node for node? */
116    kmemcheck_alloc_shadow(page, order, gfpflags, -1);
117
118    if (gfpflags & __GFP_ZERO)
119        kmemcheck_mark_initialized_pages(page, pages);
120    else
121        kmemcheck_mark_uninitialized_pages(page, pages);
122}
123

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