diff options
Diffstat (limited to 'mm/slab_common.c')
| -rw-r--r-- | mm/slab_common.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 82317abb03ed..da88c1588752 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1030,6 +1030,53 @@ void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order) EXPORT_SYMBOL(kmalloc_order_trace); #endif +#ifdef CONFIG_SLAB_FREELIST_RANDOM +/* Randomize a generic freelist */ +static void freelist_randomize(struct rnd_state *state, unsigned int *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 || cachep->random_seq) + return 0; + + cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); + if (!cachep->random_seq) + return -ENOMEM; + + /* Get best entropy at this stage of boot */ + 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 */ + #ifdef CONFIG_SLABINFO #ifdef CONFIG_SLAB |