kasan, mm: integrate slab init_on_alloc with HW_TAGS

This change uses the previously added memory initialization feature of
HW_TAGS KASAN routines for slab memory when init_on_alloc is enabled.

With this change, memory initialization memset() is no longer called when
both HW_TAGS KASAN and init_on_alloc are enabled.  Instead, memory is
initialized in KASAN runtime.

The memory initialization memset() is moved into slab_post_alloc_hook()
that currently directly follows the initialization loop.  A new argument
is added to slab_post_alloc_hook() that indicates whether to initialize
the memory or not.

To avoid discrepancies with which memory gets initialized that can be
caused by future changes, both KASAN hook and initialization memset() are
put together and a warning comment is added.

Combining setting allocation tags with memory initialization improves
HW_TAGS KASAN performance when init_on_alloc is enabled.

Link: https://lkml.kernel.org/r/c1292aeb5d519da221ec74a0684a949b027d7720.1615296150.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 15 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 4e212cda8693..84f183e9b31a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3216,6 +3216,7 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_
 	void *ptr;
 	int slab_node = numa_mem_id();
 	struct obj_cgroup *objcg = NULL;
+	bool init = false;
 
 	flags &= gfp_allowed_mask;
 	cachep = slab_pre_alloc_hook(cachep, &objcg, 1, flags);
@@ -3254,12 +3255,10 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_
   out:
 	local_irq_restore(save_flags);
 	ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
-
-	if (unlikely(slab_want_init_on_alloc(flags, cachep)) && ptr)
-		memset(ptr, 0, cachep->object_size);
+	init = slab_want_init_on_alloc(flags, cachep);
 
 out_hooks:
-	slab_post_alloc_hook(cachep, objcg, flags, 1, &ptr);
+	slab_post_alloc_hook(cachep, objcg, flags, 1, &ptr, init);
 	return ptr;
 }
 
@@ -3301,6 +3300,7 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, size_t orig_size, unsigned lo
 	unsigned long save_flags;
 	void *objp;
 	struct obj_cgroup *objcg = NULL;
+	bool init = false;
 
 	flags &= gfp_allowed_mask;
 	cachep = slab_pre_alloc_hook(cachep, &objcg, 1, flags);
@@ -3317,12 +3317,10 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, size_t orig_size, unsigned lo
 	local_irq_restore(save_flags);
 	objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
 	prefetchw(objp);
-
-	if (unlikely(slab_want_init_on_alloc(flags, cachep)) && objp)
-		memset(objp, 0, cachep->object_size);
+	init = slab_want_init_on_alloc(flags, cachep);
 
 out:
-	slab_post_alloc_hook(cachep, objcg, flags, 1, &objp);
+	slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init);
 	return objp;
 }
 
@@ -3542,18 +3540,18 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 
 	cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_);
 
-	/* Clear memory outside IRQ disabled section */
-	if (unlikely(slab_want_init_on_alloc(flags, s)))
-		for (i = 0; i < size; i++)
-			memset(p[i], 0, s->object_size);
-
-	slab_post_alloc_hook(s, objcg, flags, size, p);
+	/*
+	 * memcg and kmem_cache debug support and memory initialization.
+	 * Done outside of the IRQ disabled section.
+	 */
+	slab_post_alloc_hook(s, objcg, flags, size, p,
+				slab_want_init_on_alloc(flags, s));
 	/* FIXME: Trace call missing. Christoph would like a bulk variant */
 	return size;
 error:
 	local_irq_enable();
 	cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
-	slab_post_alloc_hook(s, objcg, flags, i, p);
+	slab_post_alloc_hook(s, objcg, flags, i, p, false);
 	__kmem_cache_free_bulk(s, i, p);
 	return 0;
 }