diff options
| author | Tao Chen <chen.dylane@linux.dev> | 2025-09-26 01:50:28 +0800 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2025-09-25 16:12:14 -0700 |
| commit | 17f0d1f6321caa95699b8f96baf12e654d7b8d60 (patch) | |
| tree | d1f316df789f191f7979ee675b68ec96e9a266fa /kernel | |
| parent | 105eb5dc74109a9f53c2f26c9a918d9347a73595 (diff) | |
bpf: Add lookup_and_delete_elem for BPF_MAP_STACK_TRACE
The stacktrace map can be easily full, which will lead to failure in
obtaining the stack. In addition to increasing the size of the map,
another solution is to delete the stack_id after looking it up from
the user, so extend the existing bpf_map_lookup_and_delete_elem()
functionality to stacktrace map types.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250925175030.1615837-1-chen.dylane@linux.dev
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/stackmap.c | 16 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 8 |
2 files changed, 19 insertions, 5 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 3615c06b7dfa..2e182a3ac4ce 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -646,7 +646,15 @@ static void *stack_map_lookup_elem(struct bpf_map *map, void *key) } /* Called from syscall */ -int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) +static int stack_map_lookup_and_delete_elem(struct bpf_map *map, void *key, + void *value, u64 flags) +{ + return bpf_stackmap_extract(map, key, value, true); +} + +/* Called from syscall */ +int bpf_stackmap_extract(struct bpf_map *map, void *key, void *value, + bool delete) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *bucket, *old_bucket; @@ -663,7 +671,10 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) memcpy(value, bucket->data, trace_len); memset(value + trace_len, 0, map->value_size - trace_len); - old_bucket = xchg(&smap->buckets[id], bucket); + if (delete) + old_bucket = bucket; + else + old_bucket = xchg(&smap->buckets[id], bucket); if (old_bucket) pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return 0; @@ -754,6 +765,7 @@ const struct bpf_map_ops stack_trace_map_ops = { .map_free = stack_map_free, .map_get_next_key = stack_map_get_next_key, .map_lookup_elem = stack_map_lookup_elem, + .map_lookup_and_delete_elem = stack_map_lookup_and_delete_elem, .map_update_elem = stack_map_update_elem, .map_delete_elem = stack_map_delete_elem, .map_check_btf = map_check_no_btf, diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index adb05d235011..a48fa86f82a7 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -320,7 +320,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value, } else if (map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) { err = bpf_percpu_cgroup_storage_copy(map, key, value); } else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) { - err = bpf_stackmap_copy(map, key, value); + err = bpf_stackmap_extract(map, key, value, false); } else if (IS_FD_ARRAY(map) || IS_FD_PROG_ARRAY(map)) { err = bpf_fd_array_map_lookup_elem(map, key, value); } else if (IS_FD_HASH(map)) { @@ -1666,7 +1666,8 @@ struct bpf_map *bpf_map_inc_not_zero(struct bpf_map *map) } EXPORT_SYMBOL_GPL(bpf_map_inc_not_zero); -int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) +int __weak bpf_stackmap_extract(struct bpf_map *map, void *key, void *value, + bool delete) { return -ENOTSUPP; } @@ -2197,7 +2198,8 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr) } else if (map->map_type == BPF_MAP_TYPE_HASH || map->map_type == BPF_MAP_TYPE_PERCPU_HASH || map->map_type == BPF_MAP_TYPE_LRU_HASH || - map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) { + map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH || + map->map_type == BPF_MAP_TYPE_STACK_TRACE) { if (!bpf_map_is_offloaded(map)) { bpf_disable_instrumentation(); rcu_read_lock(); |