diff options
| author | Qiliang Yuan <realwujing@gmail.com> | 2026-01-20 10:32:34 +0800 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2026-01-20 11:32:28 -0800 |
| commit | f81c07a6e98e3171d0c4c5ab79f5aeff71b42c44 (patch) | |
| tree | 7742b4c51a866b0e60f8f4e63aaed53390097deb /kernel | |
| parent | 713edc71449f122491f8860be49b40f27d5f46b5 (diff) | |
bpf/verifier: Optimize ID mapping reset in states_equal
Currently, reset_idmap_scratch() performs a 4.7KB memset() in every
states_equal() call. Optimize this by using a counter to track used
ID mappings, replacing the O(N) memset() with an O(1) reset and
bounding the search loop in check_ids().
Signed-off-by: Qiliang Yuan <realwujing@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260120023234.77673-1-realwujing@gmail.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 76e02e13890f..b67d8981b058 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19000,18 +19000,21 @@ static bool check_ids(u32 old_id, u32 cur_id, struct bpf_idmap *idmap) if (old_id == 0) /* cur_id == 0 as well */ return true; - for (i = 0; i < BPF_ID_MAP_SIZE; i++) { - if (!map[i].old) { - /* Reached an empty slot; haven't seen this id before */ - map[i].old = old_id; - map[i].cur = cur_id; - return true; - } + for (i = 0; i < idmap->cnt; i++) { if (map[i].old == old_id) return map[i].cur == cur_id; if (map[i].cur == cur_id) return false; } + + /* Reached the end of known mappings; haven't seen this id before */ + if (idmap->cnt < BPF_ID_MAP_SIZE) { + map[idmap->cnt].old = old_id; + map[idmap->cnt].cur = cur_id; + idmap->cnt++; + return true; + } + /* We ran out of idmap slots, which should be impossible */ WARN_ON_ONCE(1); return false; @@ -19520,8 +19523,10 @@ static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_stat static void reset_idmap_scratch(struct bpf_verifier_env *env) { - env->idmap_scratch.tmp_id_gen = env->id_gen; - memset(&env->idmap_scratch.map, 0, sizeof(env->idmap_scratch.map)); + struct bpf_idmap *idmap = &env->idmap_scratch; + + idmap->tmp_id_gen = env->id_gen; + idmap->cnt = 0; } static bool states_equal(struct bpf_verifier_env *env, |