kmemcheck.c revision ea5a9f0c3447889abceb7482c391bb977472eab9
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