LXR linux/mm/kmemcheck.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/gfp.h>
   3#include <linux/mm_types.h>
   4#include <linux/mm.h>
   5#include <linux/slab.h>
   6#include "slab.h"
   7#include <linux/kmemcheck.h>
   8
   9void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
  10{
  11        struct page *shadow;
  12        int pages;
  13        int i;
  14
  15        pages = 1 << order;
  16
  17        /*
  18         * With kmemcheck enabled, we need to allocate a memory area for the
  19         * shadow bits as well.
  20         */
  21        shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
  22        if (!shadow) {
  23                if (printk_ratelimit())
  24                        pr_err("kmemcheck: failed to allocate 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        if (unlikely(!object)) /* Skip object if allocation failed */
  64                return;
  65
  66        /*
  67         * Has already been memset(), which initializes the shadow for us
  68         * as well.
  69         */
  70        if (gfpflags & __GFP_ZERO)
  71                return;
  72
  73        /* No need to initialize the shadow of a non-tracked slab. */
  74        if (s->flags & SLAB_NOTRACK)
  75                return;
  76
  77        if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
  78                /*
  79                 * Allow notracked objects to be allocated from
  80                 * tracked caches. Note however that these objects
  81                 * will still get page faults on access, they just
  82                 * won't ever be flagged as uninitialized. If page
  83                 * faults are not acceptable, the slab cache itself
  84                 * should be marked NOTRACK.
  85                 */
  86                kmemcheck_mark_initialized(object, size);
  87        } else if (!s->ctor) {
  88                /*
  89                 * New objects should be marked uninitialized before
  90                 * they're returned to the called.
  91                 */
  92                kmemcheck_mark_uninitialized(object, size);
  93        }
  94}
  95
  96void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
  97{
  98        /* TODO: RCU freeing is unsupported for now; hide false positives. */
  99        if (!s->ctor && !(s->flags & SLAB_TYPESAFE_BY_RCU))
 100                kmemcheck_mark_freed(object, size);
 101}
 102
 103void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
 104                               gfp_t gfpflags)
 105{
 106        int pages;
 107
 108        if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
 109                return;
 110
 111        pages = 1 << order;
 112
 113        /*
 114         * NOTE: We choose to track GFP_ZERO pages too; in fact, they
 115         * can become uninitialized by copying uninitialized memory
 116         * into them.
 117         */
 118
 119        /* XXX: Can use zone->node for node? */
 120        kmemcheck_alloc_shadow(page, order, gfpflags, -1);
 121
 122        if (gfpflags & __GFP_ZERO)
 123                kmemcheck_mark_initialized_pages(page, pages);
 124        else
 125                kmemcheck_mark_uninitialized_pages(page, pages);
 126}
 127