1 files changed, 122 insertions, 0 deletions

diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
new file mode 100644
index 000000000000..fd814fd61319
--- /dev/null
+++ b/mm/kmemcheck.c
@@ -0,0 +1,122 @@
+#include <linux/gfp.h>
+#include <linux/mm_types.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/kmemcheck.h>
+
+void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
+{
+        struct page *shadow;
+        int pages;
+        int i;
+
+        pages = 1 << order;
+
+        /*
+         * With kmemcheck enabled, we need to allocate a memory area for the
+         * shadow bits as well.
+         */
+        shadow = alloc_pages_node(node, flags | __GFP_NOTRACK, order);
+        if (!shadow) {
+                if (printk_ratelimit())
+                        printk(KERN_ERR "kmemcheck: failed to allocate "
+                                "shadow bitmap\n");
+                return;
+        }
+
+        for(i = 0; i < pages; ++i)
+                page[i].shadow = page_address(&shadow[i]);
+
+        /*
+         * Mark it as non-present for the MMU so that our accesses to
+         * this memory will trigger a page fault and let us analyze
+         * the memory accesses.
+         */
+        kmemcheck_hide_pages(page, pages);
+}
+
+void kmemcheck_free_shadow(struct page *page, int order)
+{
+        struct page *shadow;
+        int pages;
+        int i;
+
+        if (!kmemcheck_page_is_tracked(page))
+                return;
+
+        pages = 1 << order;
+
+        kmemcheck_show_pages(page, pages);
+
+        shadow = virt_to_page(page[0].shadow);
+
+        for(i = 0; i < pages; ++i)
+                page[i].shadow = NULL;
+
+        __free_pages(shadow, order);
+}
+
+void kmemcheck_slab_alloc(struct kmem_cache *s, gfp_t gfpflags, void *object,
+                          size_t size)
+{
+        /*
+         * Has already been memset(), which initializes the shadow for us
+         * as well.
+         */
+        if (gfpflags & __GFP_ZERO)
+                return;
+
+        /* No need to initialize the shadow of a non-tracked slab. */
+        if (s->flags & SLAB_NOTRACK)
+                return;
+
+        if (!kmemcheck_enabled || gfpflags & __GFP_NOTRACK) {
+                /*
+                 * Allow notracked objects to be allocated from
+                 * tracked caches. Note however that these objects
+                 * will still get page faults on access, they just
+                 * won't ever be flagged as uninitialized. If page
+                 * faults are not acceptable, the slab cache itself
+                 * should be marked NOTRACK.
+                 */
+                kmemcheck_mark_initialized(object, size);
+        } else if (!s->ctor) {
+                /*
+                 * New objects should be marked uninitialized before
+                 * they're returned to the called.
+                 */
+                kmemcheck_mark_uninitialized(object, size);
+        }
+}
+
+void kmemcheck_slab_free(struct kmem_cache *s, void *object, size_t size)
+{
+        /* TODO: RCU freeing is unsupported for now; hide false positives. */
+        if (!s->ctor && !(s->flags & SLAB_DESTROY_BY_RCU))
+                kmemcheck_mark_freed(object, size);
+}
+
+void kmemcheck_pagealloc_alloc(struct page *page, unsigned int order,
+                               gfp_t gfpflags)
+{
+        int pages;
+
+        if (gfpflags & (__GFP_HIGHMEM | __GFP_NOTRACK))
+                return;
+
+        pages = 1 << order;
+
+        /*
+         * NOTE: We choose to track GFP_ZERO pages too; in fact, they
+         * can become uninitialized by copying uninitialized memory
+         * into them.
+         */
+
+        /* XXX: Can use zone->node for node? */
+        kmemcheck_alloc_shadow(page, order, gfpflags, -1);
+
+        if (gfpflags & __GFP_ZERO)
+                kmemcheck_mark_initialized_pages(page, pages);
+        else
+                kmemcheck_mark_uninitialized_pages(page, pages);
+}