aboutsummaryrefslogtreecommitdiff
path: root/mm/kmemcheck.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/kmemcheck.c')
-rw-r--r--mm/kmemcheck.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
new file mode 100644
index 00000000000..eaa41b80261
--- /dev/null
+++ b/mm/kmemcheck.c
@@ -0,0 +1,103 @@
+#include <linux/mm_types.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/kmemcheck.h>
+
+void kmemcheck_alloc_shadow(struct kmem_cache *s, gfp_t flags, int node,
+ struct page *page, int order)
+{
+ 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, 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);
+
+ /*
+ * Objects from caches that have a constructor don't get
+ * cleared when they're allocated, so we need to do it here.
+ */
+ if (s->ctor)
+ kmemcheck_mark_uninitialized_pages(page, pages);
+ else
+ kmemcheck_mark_unallocated_pages(page, pages);
+}
+
+void kmemcheck_free_shadow(struct kmem_cache *s, struct page *page, int order)
+{
+ struct page *shadow;
+ int pages;
+ int i;
+
+ 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);
+}