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