diff options
| author | Jiri Olsa <jolsa@kernel.org> | 2026-08-03 23:01:39 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2026-08-05 11:32:29 -0700 |
| commit | 0ca56befcffec3a6c9d1842eae06c74e1cf41f11 (patch) | |
| tree | 1edb54a5b4c69034ba1e79dc60a17c427d329e37 /kernel | |
| parent | 15b837759a97237d647962f9943afe0d55af615a (diff) | |
bpf: Factor stackid_fastpath function from __bpf_get_stackid
The new stackid_fastpath does the fast stack hash and trace check, that
does not need new bucket allocation. It covers both just-ip and buildid
code paths.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260803210149.296496-3-jolsa@kernel.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/stackmap.c | 43 |
1 files changed, 28 insertions, 15 deletions
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 19f9ea605a3e..27210b5d16fc 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -511,6 +511,7 @@ struct stackid { u32 len; u32 hash; u32 id; + bool hash_matches; }; static int stackid_init(struct stackid *stackid, struct bpf_map *map, @@ -531,28 +532,46 @@ static int stackid_init(struct stackid *stackid, struct bpf_map *map, stackid->hash = jhash2((u32 *)stackid->ips, stackid->len / sizeof(u32), 0); stackid->id = stackid->hash & (smap->n_buckets - 1); stackid->bucket = READ_ONCE(smap->buckets[stackid->id]); + stackid->hash_matches = stackid->bucket && stackid->bucket->hash == stackid->hash; return 0; } +static int stackid_fastpath(struct stackid *stackid, struct bpf_map *map, + struct perf_callchain_entry *trace, u64 flags) +{ + int err; + + err = stackid_init(stackid, map, trace, flags); + if (err) + return err; + + /* fast cmp */ + if (stackid->hash_matches && flags & BPF_F_FAST_STACK_CMP) + return stackid->id; + + if (stack_map_use_build_id(map)) + return -ENOENT; + if (stackid->hash_matches && stackid->bucket->nr == stackid->nr && + memcmp(stackid->bucket->data, stackid->ips, stackid->len) == 0) + return stackid->id; + if (stackid->bucket && !(flags & BPF_F_REUSE_STACKID)) + return -EEXIST; + return -ENOENT; +} + static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, struct perf_callchain_entry *trace, u64 flags) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *new_bucket, *old_bucket; bool user = flags & BPF_F_USER_STACK; - bool hash_matches; u32 trace_len, i; int err; - err = stackid_init(stackid, map, trace, flags); - if (err) + err = stackid_fastpath(stackid, map, trace, flags); + if (err != -ENOENT) return err; - hash_matches = stackid->bucket && stackid->bucket->hash == stackid->hash; - /* fast cmp */ - if (hash_matches && flags & BPF_F_FAST_STACK_CMP) - return stackid->id; - if (stack_map_use_build_id(map)) { struct bpf_stack_build_id *id_offs; @@ -567,7 +586,7 @@ static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, id_offs[i].ip = stackid->ips[i]; stack_map_get_build_id_offset(id_offs, stackid->nr, user, false /* !may_fault */); trace_len = stackid->nr * sizeof(struct bpf_stack_build_id); - if (hash_matches && stackid->bucket->nr == stackid->nr && + if (stackid->hash_matches && stackid->bucket->nr == stackid->nr && memcmp(stackid->bucket->data, new_bucket->data, trace_len) == 0) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return stackid->id; @@ -577,12 +596,6 @@ static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, return -EEXIST; } } else { - if (hash_matches && stackid->bucket->nr == stackid->nr && - memcmp(stackid->bucket->data, stackid->ips, stackid->len) == 0) - return stackid->id; - if (stackid->bucket && !(flags & BPF_F_REUSE_STACKID)) - return -EEXIST; - new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) |