kmemcheck: add mm functions

[net-next-2.6.git] / mm / kmemcheck.c

diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
new file mode 100644 (file)
index 0000000..eaa41b8
--- /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);
+}