Commit c6936161 authored by Leon Hwang's avatar Leon Hwang Committed by Alexei Starovoitov
Browse files

bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps 



Introduce BPF_F_ALL_CPUS flag support for percpu_hash and lru_percpu_hash
maps to allow updating values for all CPUs with a single value for both
update_elem and update_batch APIs.

Introduce BPF_F_CPU flag support for percpu_hash and lru_percpu_hash
maps to allow:

* update value for specified CPU for both update_elem and update_batch
APIs.
* lookup value for specified CPU for both lookup_elem and lookup_batch
APIs.

The BPF_F_CPU flag is passed via:

* map_flags along with embedded cpu info.
* elem_flags along with embedded cpu info.

Signed-off-by: default avatarLeon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260107022022.12843-4-leon.hwang@linux.dev


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 8eb76cb0

include/linux/bpf.h

+3 −1
Original line number Diff line number Diff line
@@ -2847,7 +2847,7 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env, 
				   struct bpf_func_state *caller,

				   struct bpf_func_state *callee);



int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value, u64 flags);

int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value, u64 flags);

int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,

			   u64 flags);
@@ -3919,6 +3919,8 @@ static inline bool bpf_map_supports_cpu_flags(enum bpf_map_type map_type) 
{

	switch (map_type) {

	case BPF_MAP_TYPE_PERCPU_ARRAY:

	case BPF_MAP_TYPE_PERCPU_HASH:

	case BPF_MAP_TYPE_LRU_PERCPU_HASH:

		return true;

	default:

		return false;

kernel/bpf/hashtab.c

+64 −30
Original line number Diff line number Diff line
@@ -932,7 +932,7 @@ static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l) 
}



static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,

			    void *value, bool onallcpus)

			    void *value, bool onallcpus, u64 map_flags)

{

	void *ptr;
@@ -943,19 +943,28 @@ static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr, 
		bpf_obj_free_fields(htab->map.record, ptr);

	} else {

		u32 size = round_up(htab->map.value_size, 8);

		int off = 0, cpu;

		void *val;

		int cpu;



		if (map_flags & BPF_F_CPU) {

			cpu = map_flags >> 32;

			ptr = per_cpu_ptr(pptr, cpu);

			copy_map_value(&htab->map, ptr, value);

			bpf_obj_free_fields(htab->map.record, ptr);

			return;

		}



		for_each_possible_cpu(cpu) {

			ptr = per_cpu_ptr(pptr, cpu);

			copy_map_value_long(&htab->map, ptr, value + off);

			val = (map_flags & BPF_F_ALL_CPUS) ? value : value + size * cpu;

			copy_map_value(&htab->map, ptr, val);

			bpf_obj_free_fields(htab->map.record, ptr);

			off += size;

		}

	}

}



static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,

			    void *value, bool onallcpus)

			    void *value, bool onallcpus, u64 map_flags)

{

	/* When not setting the initial value on all cpus, zero-fill element

	 * values for other cpus. Otherwise, bpf program has no way to ensure
@@ -973,7 +982,7 @@ static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr, 
				zero_map_value(&htab->map, per_cpu_ptr(pptr, cpu));

		}

	} else {

		pcpu_copy_value(htab, pptr, value, onallcpus);

		pcpu_copy_value(htab, pptr, value, onallcpus, map_flags);

	}

}
@@ -985,7 +994,7 @@ static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab) 
static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,

					 void *value, u32 key_size, u32 hash,

					 bool percpu, bool onallcpus,

					 struct htab_elem *old_elem)

					 struct htab_elem *old_elem, u64 map_flags)

{

	u32 size = htab->map.value_size;

	bool prealloc = htab_is_prealloc(htab);
@@ -1043,7 +1052,7 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key, 
			pptr = *(void __percpu **)ptr;

		}



		pcpu_init_value(htab, pptr, value, onallcpus);

		pcpu_init_value(htab, pptr, value, onallcpus, map_flags);



		if (!prealloc)

			htab_elem_set_ptr(l_new, key_size, pptr);
@@ -1147,7 +1156,7 @@ static long htab_map_update_elem(struct bpf_map *map, void *key, void *value, 
	}



	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,

				l_old);

				l_old, map_flags);

	if (IS_ERR(l_new)) {

		/* all pre-allocated elements are in use or memory exhausted */

		ret = PTR_ERR(l_new);
@@ -1249,6 +1258,15 @@ static long htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value 
	return ret;

}



static int htab_map_check_update_flags(bool onallcpus, u64 map_flags)

{

	if (unlikely(!onallcpus && map_flags > BPF_EXIST))

		return -EINVAL;

	if (unlikely(onallcpus && ((map_flags & BPF_F_LOCK) || (u32)map_flags > BPF_F_ALL_CPUS)))

		return -EINVAL;

	return 0;

}



static long htab_map_update_elem_in_place(struct bpf_map *map, void *key,

					  void *value, u64 map_flags,

					  bool percpu, bool onallcpus)
@@ -1262,9 +1280,9 @@ static long htab_map_update_elem_in_place(struct bpf_map *map, void *key, 
	u32 key_size, hash;

	int ret;



	if (unlikely(map_flags > BPF_EXIST))

		/* unknown flags */

		return -EINVAL;

	ret = htab_map_check_update_flags(onallcpus, map_flags);

	if (unlikely(ret))

		return ret;



	WARN_ON_ONCE(!bpf_rcu_lock_held());
@@ -1289,7 +1307,7 @@ static long htab_map_update_elem_in_place(struct bpf_map *map, void *key, 
		/* Update value in-place */

		if (percpu) {

			pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),

					value, onallcpus);

					value, onallcpus, map_flags);

		} else {

			void **inner_map_pptr = htab_elem_value(l_old, key_size);
@@ -1298,7 +1316,7 @@ static long htab_map_update_elem_in_place(struct bpf_map *map, void *key, 
		}

	} else {

		l_new = alloc_htab_elem(htab, key, value, key_size,

					hash, percpu, onallcpus, NULL);

					hash, percpu, onallcpus, NULL, map_flags);

		if (IS_ERR(l_new)) {

			ret = PTR_ERR(l_new);

			goto err;
@@ -1324,9 +1342,9 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, 
	u32 key_size, hash;

	int ret;



	if (unlikely(map_flags > BPF_EXIST))

		/* unknown flags */

		return -EINVAL;

	ret = htab_map_check_update_flags(onallcpus, map_flags);

	if (unlikely(ret))

		return ret;



	WARN_ON_ONCE(!bpf_rcu_lock_held());
@@ -1363,10 +1381,10 @@ static long __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, 


		/* per-cpu hash map can update value in-place */

		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),

				value, onallcpus);

				value, onallcpus, map_flags);

	} else {

		pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),

				value, onallcpus);

				value, onallcpus, map_flags);

		hlist_nulls_add_head_rcu(&l_new->hash_node, head);

		l_new = NULL;

	}
@@ -1678,9 +1696,9 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
	void __user *ukeys = u64_to_user_ptr(attr->batch.keys);

	void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);

	u32 batch, max_count, size, bucket_size, map_id;

	u64 elem_map_flags, map_flags, allowed_flags;

	u32 bucket_cnt, total, key_size, value_size;

	struct htab_elem *node_to_free = NULL;

	u64 elem_map_flags, map_flags;

	struct hlist_nulls_head *head;

	struct hlist_nulls_node *n;

	unsigned long flags = 0;
@@ -1690,9 +1708,12 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
	int ret = 0;



	elem_map_flags = attr->batch.elem_flags;

	if ((elem_map_flags & ~BPF_F_LOCK) ||

	    ((elem_map_flags & BPF_F_LOCK) && !btf_record_has_field(map->record, BPF_SPIN_LOCK)))

		return -EINVAL;

	allowed_flags = BPF_F_LOCK;

	if (!do_delete && is_percpu)

		allowed_flags |= BPF_F_CPU;

	ret = bpf_map_check_op_flags(map, elem_map_flags, allowed_flags);

	if (ret)

		return ret;



	map_flags = attr->batch.flags;

	if (map_flags)
@@ -1715,7 +1736,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
	key_size = htab->map.key_size;

	value_size = htab->map.value_size;

	size = round_up(value_size, 8);

	if (is_percpu)

	if (is_percpu && !(elem_map_flags & BPF_F_CPU))

		value_size = size * num_possible_cpus();

	total = 0;

	/* while experimenting with hash tables with sizes ranging from 10 to
@@ -1798,11 +1819,18 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, 
			void __percpu *pptr;



			pptr = htab_elem_get_ptr(l, map->key_size);

			if (elem_map_flags & BPF_F_CPU) {

				cpu = elem_map_flags >> 32;

				copy_map_value(&htab->map, dst_val, per_cpu_ptr(pptr, cpu));

				check_and_init_map_value(&htab->map, dst_val);

			} else {

				for_each_possible_cpu(cpu) {

				copy_map_value_long(&htab->map, dst_val + off, per_cpu_ptr(pptr, cpu));

					copy_map_value_long(&htab->map, dst_val + off,

							    per_cpu_ptr(pptr, cpu));

					check_and_init_map_value(&htab->map, dst_val + off);

					off += size;

				}

			}

		} else {

			value = htab_elem_value(l, key_size);

			if (is_fd_htab(htab)) {
@@ -2357,7 +2385,7 @@ static void *htab_lru_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *k 
	return NULL;

}



int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value, u64 map_flags)

{

	struct htab_elem *l;

	void __percpu *pptr;
@@ -2374,16 +2402,22 @@ int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value) 
	l = __htab_map_lookup_elem(map, key);

	if (!l)

		goto out;

	ret = 0;

	/* We do not mark LRU map element here in order to not mess up

	 * eviction heuristics when user space does a map walk.

	 */

	pptr = htab_elem_get_ptr(l, map->key_size);

	if (map_flags & BPF_F_CPU) {

		cpu = map_flags >> 32;

		copy_map_value(map, value, per_cpu_ptr(pptr, cpu));

		check_and_init_map_value(map, value);

		goto out;

	}

	for_each_possible_cpu(cpu) {

		copy_map_value_long(map, value + off, per_cpu_ptr(pptr, cpu));

		check_and_init_map_value(map, value + off);

		off += size;

	}

	ret = 0;

out:

	rcu_read_unlock();

	return ret;

kernel/bpf/syscall.c

+1 −1
Original line number Diff line number Diff line
@@ -316,7 +316,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value, 
	bpf_disable_instrumentation();

	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||

	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {

		err = bpf_percpu_hash_copy(map, key, value);

		err = bpf_percpu_hash_copy(map, key, value, flags);

	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {

		err = bpf_percpu_array_copy(map, key, value, flags);

	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {