#include <linux/gfp.h>

  #include <linux/mm_types.h>
  #include <linux/mm.h>
  #include <linux/slab.h>

  #include "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())

  			pr_err("kmemcheck: failed to allocate shadow bitmap
  ");

  		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)
  {

  	if (unlikely(!object)) /* Skip object if allocation failed */
  		return;

  	/*
  	 * 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);
  }