diff options
| -rw-r--r-- | include/linux/kfence.h | 21 | ||||
| -rw-r--r-- | mm/kfence/core.c | 16 |
2 files changed, 18 insertions, 19 deletions
diff --git a/include/linux/kfence.h b/include/linux/kfence.h index 3fe6dd8a18c1..4b5e3679a72c 100644 --- a/include/linux/kfence.h +++ b/include/linux/kfence.h @@ -14,6 +14,9 @@ #ifdef CONFIG_KFENCE +#include <linux/atomic.h> +#include <linux/static_key.h> + /* * We allocate an even number of pages, as it simplifies calculations to map * address to metadata indices; effectively, the very first page serves as an @@ -22,13 +25,8 @@ #define KFENCE_POOL_SIZE ((CONFIG_KFENCE_NUM_OBJECTS + 1) * 2 * PAGE_SIZE) extern char *__kfence_pool; -#ifdef CONFIG_KFENCE_STATIC_KEYS -#include <linux/static_key.h> DECLARE_STATIC_KEY_FALSE(kfence_allocation_key); -#else -#include <linux/atomic.h> extern atomic_t kfence_allocation_gate; -#endif /** * is_kfence_address() - check if an address belongs to KFENCE pool @@ -116,13 +114,16 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags); */ static __always_inline void *kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) { -#ifdef CONFIG_KFENCE_STATIC_KEYS - if (static_branch_unlikely(&kfence_allocation_key)) +#if defined(CONFIG_KFENCE_STATIC_KEYS) || CONFIG_KFENCE_SAMPLE_INTERVAL == 0 + if (!static_branch_unlikely(&kfence_allocation_key)) + return NULL; #else - if (unlikely(!atomic_read(&kfence_allocation_gate))) + if (!static_branch_likely(&kfence_allocation_key)) + return NULL; #endif - return __kfence_alloc(s, size, flags); - return NULL; + if (likely(atomic_read(&kfence_allocation_gate))) + return NULL; + return __kfence_alloc(s, size, flags); } /** diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 802905b1c89b..09945784df9e 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -104,10 +104,11 @@ struct kfence_metadata kfence_metadata[CONFIG_KFENCE_NUM_OBJECTS]; static struct list_head kfence_freelist = LIST_HEAD_INIT(kfence_freelist); static DEFINE_RAW_SPINLOCK(kfence_freelist_lock); /* Lock protecting freelist. */ -#ifdef CONFIG_KFENCE_STATIC_KEYS -/* The static key to set up a KFENCE allocation. */ +/* + * The static key to set up a KFENCE allocation; or if static keys are not used + * to gate allocations, to avoid a load and compare if KFENCE is disabled. + */ DEFINE_STATIC_KEY_FALSE(kfence_allocation_key); -#endif /* Gates the allocation, ensuring only one succeeds in a given period. */ atomic_t kfence_allocation_gate = ATOMIC_INIT(1); @@ -774,6 +775,8 @@ void __init kfence_init(void) return; } + if (!IS_ENABLED(CONFIG_KFENCE_STATIC_KEYS)) + static_branch_enable(&kfence_allocation_key); WRITE_ONCE(kfence_enabled, true); queue_delayed_work(system_unbound_wq, &kfence_timer, 0); pr_info("initialized - using %lu bytes for %d objects at 0x%p-0x%p\n", KFENCE_POOL_SIZE, @@ -866,12 +869,7 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) return NULL; } - /* - * allocation_gate only needs to become non-zero, so it doesn't make - * sense to continue writing to it and pay the associated contention - * cost, in case we have a large number of concurrent allocations. - */ - if (atomic_read(&kfence_allocation_gate) || atomic_inc_return(&kfence_allocation_gate) > 1) + if (atomic_inc_return(&kfence_allocation_gate) > 1) return NULL; #ifdef CONFIG_KFENCE_STATIC_KEYS /* |