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Message-Id: <1464124523-43051-2-git-send-email-thgarnie@google.com>
Date: Tue, 24 May 2016 14:15:22 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
Pranith Kumar <bobby.prani@...il.com>,
David Howells <dhowells@...hat.com>, Tejun Heo <tj@...nel.org>,
Johannes Weiner <hannes@...xchg.org>,
David Woodhouse <David.Woodhouse@...el.com>,
Thomas Garnier <thgarnie@...gle.com>,
Petr Mladek <pmladek@...e.com>,
Kees Cook <keescook@...omium.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
gthelen@...gle.com, kernel-hardening@...ts.openwall.com
Subject: [RFC v2 1/2] mm: Reorganize SLAB freelist randomization
This commit reorganizes the previous SLAB freelist randomization to
prepare for the SLUB implementation. It moves functions that will be
shared to slab_common. It also move the definition of freelist_idx_t in
the slab_def header so a similar type can be used for all common
functions. The entropy functions are changed to align with the SLUB
implementation, now using get_random_* functions.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
Based on 0e01df100b6bf22a1de61b66657502a6454153c5
---
include/linux/slab_def.h | 11 +++++++-
mm/slab.c | 68 ++----------------------------------------------
mm/slab.h | 16 ++++++++++++
mm/slab_common.c | 48 ++++++++++++++++++++++++++++++++++
4 files changed, 76 insertions(+), 67 deletions(-)
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 8694f7a..e05a871 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -3,6 +3,15 @@
#include <linux/reciprocal_div.h>
+#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
+ <= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
+
+#if FREELIST_BYTE_INDEX
+typedef unsigned char freelist_idx_t;
+#else
+typedef unsigned short freelist_idx_t;
+#endif
+
/*
* Definitions unique to the original Linux SLAB allocator.
*/
@@ -81,7 +90,7 @@ struct kmem_cache {
#endif
#ifdef CONFIG_SLAB_FREELIST_RANDOM
- void *random_seq;
+ freelist_idx_t *random_seq;
#endif
struct kmem_cache_node *node[MAX_NUMNODES];
diff --git a/mm/slab.c b/mm/slab.c
index cc8bbc1..8e32562 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -157,15 +157,6 @@
#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
#endif
-#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
- <= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
-
-#if FREELIST_BYTE_INDEX
-typedef unsigned char freelist_idx_t;
-#else
-typedef unsigned short freelist_idx_t;
-#endif
-
#define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
/*
@@ -1236,61 +1227,6 @@ static void __init set_up_node(struct kmem_cache *cachep, int index)
}
}
-#ifdef CONFIG_SLAB_FREELIST_RANDOM
-static void freelist_randomize(struct rnd_state *state, freelist_idx_t *list,
- size_t count)
-{
- size_t i;
- unsigned int rand;
-
- for (i = 0; i < count; i++)
- list[i] = i;
-
- /* Fisher-Yates shuffle */
- for (i = count - 1; i > 0; i--) {
- rand = prandom_u32_state(state);
- rand %= (i + 1);
- swap(list[i], list[rand]);
- }
-}
-
-/* Create a random sequence per cache */
-static int cache_random_seq_create(struct kmem_cache *cachep, gfp_t gfp)
-{
- unsigned int seed, count = cachep->num;
- struct rnd_state state;
-
- if (count < 2)
- return 0;
-
- /* If it fails, we will just use the global lists */
- cachep->random_seq = kcalloc(count, sizeof(freelist_idx_t), gfp);
- if (!cachep->random_seq)
- return -ENOMEM;
-
- /* Get best entropy at this stage */
- get_random_bytes_arch(&seed, sizeof(seed));
- prandom_seed_state(&state, seed);
-
- freelist_randomize(&state, cachep->random_seq, count);
- return 0;
-}
-
-/* Destroy the per-cache random freelist sequence */
-static void cache_random_seq_destroy(struct kmem_cache *cachep)
-{
- kfree(cachep->random_seq);
- cachep->random_seq = NULL;
-}
-#else
-static inline int cache_random_seq_create(struct kmem_cache *cachep, gfp_t gfp)
-{
- return 0;
-}
-static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
-#endif /* CONFIG_SLAB_FREELIST_RANDOM */
-
-
/*
* Initialisation. Called after the page allocator have been initialised and
* before smp_init().
@@ -2554,7 +2490,7 @@ static bool freelist_state_initialize(union freelist_init_state *state,
unsigned int rand;
/* Use best entropy available to define a random shift */
- get_random_bytes_arch(&rand, sizeof(rand));
+ rand = get_random_int();
/* Use a random state if the pre-computed list is not available */
if (!cachep->random_seq) {
@@ -3979,7 +3915,7 @@ static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
int shared = 0;
int batchcount = 0;
- err = cache_random_seq_create(cachep, gfp);
+ err = cache_random_seq_create(cachep, cachep->num, gfp);
if (err)
goto end;
diff --git a/mm/slab.h b/mm/slab.h
index dedb1a9..2c33bf3 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -42,6 +42,7 @@ struct kmem_cache {
#include <linux/kmemcheck.h>
#include <linux/kasan.h>
#include <linux/kmemleak.h>
+#include <linux/random.h>
/*
* State of the slab allocator.
@@ -464,4 +465,19 @@ int memcg_slab_show(struct seq_file *m, void *p);
void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr);
+#ifdef CONFIG_SLAB_FREELIST_RANDOM
+void freelist_randomize(struct rnd_state *state, freelist_idx_t *list,
+ size_t count);
+int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
+ gfp_t gfp);
+void cache_random_seq_destroy(struct kmem_cache *cachep);
+#else
+static inline int cache_random_seq_create(struct kmem_cache *cachep,
+ unsigned int count, gfp_t gfp)
+{
+ return 0;
+}
+static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
+#endif /* CONFIG_SLAB_FREELIST_RANDOM */
+
#endif /* MM_SLAB_H */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a65dad7..657ecf1 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1142,6 +1142,54 @@ int memcg_slab_show(struct seq_file *m, void *p)
}
#endif
+#ifdef CONFIG_SLAB_FREELIST_RANDOM
+/* Randomize a generic freelist */
+void freelist_randomize(struct rnd_state *state, freelist_idx_t *list,
+ size_t count)
+{
+ size_t i;
+ unsigned int rand;
+
+ for (i = 0; i < count; i++)
+ list[i] = i;
+
+ /* Fisher-Yates shuffle */
+ for (i = count - 1; i > 0; i--) {
+ rand = prandom_u32_state(state);
+ rand %= (i + 1);
+ swap(list[i], list[rand]);
+ }
+}
+
+/* Create a random sequence per cache */
+int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
+ gfp_t gfp)
+{
+ struct rnd_state state;
+
+ if (count < 2)
+ return 0;
+
+ /* If it fails, we will just use the global lists */
+ cachep->random_seq = kcalloc(count, sizeof(freelist_idx_t), gfp);
+ if (!cachep->random_seq)
+ return -ENOMEM;
+
+ /* Get best entropy at this stage */
+ prandom_seed_state(&state, get_random_long());
+
+ freelist_randomize(&state, cachep->random_seq, count);
+ return 0;
+}
+
+/* Destroy the per-cache random freelist sequence */
+void cache_random_seq_destroy(struct kmem_cache *cachep)
+{
+ kfree(cachep->random_seq);
+ cachep->random_seq = NULL;
+}
+#endif /* CONFIG_SLAB_FREELIST_RANDOM */
+
/*
* slabinfo_op - iterator that generates /proc/slabinfo
*
--
2.8.0.rc3.226.g39d4020
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