Add libbpf support for the BPF_F_CPU flag for percpu maps by embedding the cpu info into the high 32 bits of:
1. **flags**: bpf_map_lookup_elem_flags(), bpf_map__lookup_elem(), bpf_map_update_elem() and bpf_map__update_elem() 2. **opts->elem_flags**: bpf_map_lookup_batch() and bpf_map_update_batch()
And the flag can be BPF_F_ALL_CPUS, but cannot be 'BPF_F_CPU | BPF_F_ALL_CPUS'.
Behavior:
* If the flag is BPF_F_ALL_CPUS, the update is applied across all CPUs. * If the flag is BPF_F_CPU, it updates value only to the specified CPU. * If the flag is BPF_F_CPU, lookup value only from the specified CPU. * lookup does not support BPF_F_ALL_CPUS.
Acked-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Leon Hwang leon.hwang@linux.dev --- tools/lib/bpf/bpf.h | 8 ++++++++ tools/lib/bpf/libbpf.c | 26 ++++++++++++++++++++------ tools/lib/bpf/libbpf.h | 21 ++++++++------------- 3 files changed, 36 insertions(+), 19 deletions(-)
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h index e983a3e40d612..ffd93feffd71d 100644 --- a/tools/lib/bpf/bpf.h +++ b/tools/lib/bpf/bpf.h @@ -289,6 +289,14 @@ LIBBPF_API int bpf_map_lookup_and_delete_batch(int fd, void *in_batch, * Update spin_lock-ed map elements. This must be * specified if the map value contains a spinlock. * + * **BPF_F_CPU** + * As for percpu maps, update value on the specified CPU. And the cpu + * info is embedded into the high 32 bits of **opts->elem_flags**. + * + * **BPF_F_ALL_CPUS** + * As for percpu maps, update value across all CPUs. This flag cannot + * be used with BPF_F_CPU at the same time. + * * @param fd BPF map file descriptor * @param keys pointer to an array of *count* keys * @param values pointer to an array of *count* values diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 706e7481bdf6b..65b9b5e955449 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10913,7 +10913,7 @@ bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name) }
static int validate_map_op(const struct bpf_map *map, size_t key_sz, - size_t value_sz, bool check_value_sz) + size_t value_sz, bool check_value_sz, __u64 flags) { if (!map_is_created(map)) /* map is not yet created */ return -ENOENT; @@ -10940,6 +10940,20 @@ static int validate_map_op(const struct bpf_map *map, size_t key_sz, int num_cpu = libbpf_num_possible_cpus(); size_t elem_sz = roundup(map->def.value_size, 8);
+ if (flags & (BPF_F_CPU | BPF_F_ALL_CPUS)) { + if ((flags & BPF_F_CPU) && (flags & BPF_F_ALL_CPUS)) { + pr_warn("map '%s': BPF_F_CPU and BPF_F_ALL_CPUS are mutually exclusive\n", + map->name); + return -EINVAL; + } + if (map->def.value_size != value_sz) { + pr_warn("map '%s': unexpected value size %zu provided for either BPF_F_CPU or BPF_F_ALL_CPUS, expected %u\n", + map->name, value_sz, map->def.value_size); + return -EINVAL; + } + break; + } + if (value_sz != num_cpu * elem_sz) { pr_warn("map '%s': unexpected value size %zu provided for per-CPU map, expected %d * %zu = %zd\n", map->name, value_sz, num_cpu, elem_sz, num_cpu * elem_sz); @@ -10964,7 +10978,7 @@ int bpf_map__lookup_elem(const struct bpf_map *map, { int err;
- err = validate_map_op(map, key_sz, value_sz, true); + err = validate_map_op(map, key_sz, value_sz, true, flags); if (err) return libbpf_err(err);
@@ -10977,7 +10991,7 @@ int bpf_map__update_elem(const struct bpf_map *map, { int err;
- err = validate_map_op(map, key_sz, value_sz, true); + err = validate_map_op(map, key_sz, value_sz, true, flags); if (err) return libbpf_err(err);
@@ -10989,7 +11003,7 @@ int bpf_map__delete_elem(const struct bpf_map *map, { int err;
- err = validate_map_op(map, key_sz, 0, false /* check_value_sz */); + err = validate_map_op(map, key_sz, 0, false /* check_value_sz */, flags); if (err) return libbpf_err(err);
@@ -11002,7 +11016,7 @@ int bpf_map__lookup_and_delete_elem(const struct bpf_map *map, { int err;
- err = validate_map_op(map, key_sz, value_sz, true); + err = validate_map_op(map, key_sz, value_sz, true, flags); if (err) return libbpf_err(err);
@@ -11014,7 +11028,7 @@ int bpf_map__get_next_key(const struct bpf_map *map, { int err;
- err = validate_map_op(map, key_sz, 0, false /* check_value_sz */); + err = validate_map_op(map, key_sz, 0, false /* check_value_sz */, 0); if (err) return libbpf_err(err);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5118d0a90e243..7c38b2e546080 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -1196,12 +1196,13 @@ LIBBPF_API struct bpf_map *bpf_map__inner_map(struct bpf_map *map); * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size** * @param value pointer to memory in which looked up value will be stored * @param value_sz size in byte of value data memory; it has to match BPF map - * definition's **value_size**. For per-CPU BPF maps value size has to be - * a product of BPF map value size and number of possible CPUs in the system - * (could be fetched with **libbpf_num_possible_cpus()**). Note also that for - * per-CPU values value size has to be aligned up to closest 8 bytes for - * alignment reasons, so expected size is: `round_up(value_size, 8) - * * libbpf_num_possible_cpus()`. + * definition's **value_size**. For per-CPU BPF maps, value size can be + * `value_size` if either **BPF_F_CPU** or **BPF_F_ALL_CPUS** is specified + * in **flags**, otherwise a product of BPF map value size and number of + * possible CPUs in the system (could be fetched with + * **libbpf_num_possible_cpus()**). Note also that for per-CPU values value + * size has to be aligned up to closest 8 bytes, so expected size is: + * `round_up(value_size, 8) * libbpf_num_possible_cpus()`. * @flags extra flags passed to kernel for this operation * @return 0, on success; negative error, otherwise * @@ -1219,13 +1220,7 @@ LIBBPF_API int bpf_map__lookup_elem(const struct bpf_map *map, * @param key pointer to memory containing bytes of the key * @param key_sz size in bytes of key data, needs to match BPF map definition's **key_size** * @param value pointer to memory containing bytes of the value - * @param value_sz size in byte of value data memory; it has to match BPF map - * definition's **value_size**. For per-CPU BPF maps value size has to be - * a product of BPF map value size and number of possible CPUs in the system - * (could be fetched with **libbpf_num_possible_cpus()**). Note also that for - * per-CPU values value size has to be aligned up to closest 8 bytes for - * alignment reasons, so expected size is: `round_up(value_size, 8) - * * libbpf_num_possible_cpus()`. + * @param value_sz refer to **bpf_map__lookup_elem**'s description.' * @flags extra flags passed to kernel for this operation * @return 0, on success; negative error, otherwise *