}
}
+#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().
int i;
struct kmem_cache_node *n;
+ cache_random_seq_destroy(cachep);
+
free_percpu(cachep->cpu_cache);
/* NUMA: free the node structures */
#endif
}
+#ifdef CONFIG_SLAB_FREELIST_RANDOM
+/* Hold information during a freelist initialization */
+union freelist_init_state {
+ struct {
+ unsigned int pos;
+ freelist_idx_t *list;
+ unsigned int count;
+ unsigned int rand;
+ };
+ struct rnd_state rnd_state;
+};
+
+/*
+ * Initialize the state based on the randomization methode available.
+ * return true if the pre-computed list is available, false otherwize.
+ */
+static bool freelist_state_initialize(union freelist_init_state *state,
+ struct kmem_cache *cachep,
+ unsigned int count)
+{
+ bool ret;
+ unsigned int rand;
+
+ /* Use best entropy available to define a random shift */
+ get_random_bytes_arch(&rand, sizeof(rand));
+
+ /* Use a random state if the pre-computed list is not available */
+ if (!cachep->random_seq) {
+ prandom_seed_state(&state->rnd_state, rand);
+ ret = false;
+ } else {
+ state->list = cachep->random_seq;
+ state->count = count;
+ state->pos = 0;
+ state->rand = rand;
+ ret = true;
+ }
+ return ret;
+}
+
+/* Get the next entry on the list and randomize it using a random shift */
+static freelist_idx_t next_random_slot(union freelist_init_state *state)
+{
+ return (state->list[state->pos++] + state->rand) % state->count;
+}
+
+/*
+ * Shuffle the freelist initialization state based on pre-computed lists.
+ * return true if the list was successfully shuffled, false otherwise.
+ */
+static bool shuffle_freelist(struct kmem_cache *cachep, struct page *page)
+{
+ unsigned int objfreelist = 0, i, count = cachep->num;
+ union freelist_init_state state;
+ bool precomputed;
+
+ if (count < 2)
+ return false;
+
+ precomputed = freelist_state_initialize(&state, cachep, count);
+
+ /* Take a random entry as the objfreelist */
+ if (OBJFREELIST_SLAB(cachep)) {
+ if (!precomputed)
+ objfreelist = count - 1;
+ else
+ objfreelist = next_random_slot(&state);
+ page->freelist = index_to_obj(cachep, page, objfreelist) +
+ obj_offset(cachep);
+ count--;
+ }
+
+ /*
+ * On early boot, generate the list dynamically.
+ * Later use a pre-computed list for speed.
+ */
+ if (!precomputed) {
+ freelist_randomize(&state.rnd_state, page->freelist, count);
+ } else {
+ for (i = 0; i < count; i++)
+ set_free_obj(page, i, next_random_slot(&state));
+ }
+
+ if (OBJFREELIST_SLAB(cachep))
+ set_free_obj(page, cachep->num - 1, objfreelist);
+
+ return true;
+}
+#else
+static inline bool shuffle_freelist(struct kmem_cache *cachep,
+ struct page *page)
+{
+ return false;
+}
+#endif /* CONFIG_SLAB_FREELIST_RANDOM */
+
static void cache_init_objs(struct kmem_cache *cachep,
struct page *page)
{
int i;
void *objp;
+ bool shuffled;
cache_init_objs_debug(cachep, page);
- if (OBJFREELIST_SLAB(cachep)) {
+ /* Try to randomize the freelist if enabled */
+ shuffled = shuffle_freelist(cachep, page);
+
+ if (!shuffled && OBJFREELIST_SLAB(cachep)) {
page->freelist = index_to_obj(cachep, page, cachep->num - 1) +
obj_offset(cachep);
}
kasan_poison_object_data(cachep, objp);
}
- set_free_obj(page, i, i);
+ if (!shuffled)
+ set_free_obj(page, i, i);
}
}
int shared = 0;
int batchcount = 0;
+ err = cache_random_seq_create(cachep, gfp);
+ if (err)
+ goto end;
+
if (!is_root_cache(cachep)) {
struct kmem_cache *root = memcg_root_cache(cachep);
limit = root->limit;
batchcount = (limit + 1) / 2;
skip_setup:
err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
+end:
if (err)
pr_err("enable_cpucache failed for %s, error %d\n",
cachep->name, -err);
projects / linux-2.6-microblaze.git / commitdiff