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Linux/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 "slab.h"
  6 #include <linux/kmemcheck.h>
  7 
  8 void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
  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          */
 20         shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
 21         if (!shadow) {
 22                 if (printk_ratelimit())
 23                         pr_err("kmemcheck: failed to allocate 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 
 38 void 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 
 59 void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
 60                           size_t size)
 61 {
 62         if (unlikely(!object)) /* Skip object if allocation failed */
 63                 return;
 64 
 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 
 95 void 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 }
101 
102 void 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 }
126 

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