From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 609623F44C8 for ; Wed, 5 Aug 2026 09:29:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785922150; cv=none; b=jpECG8vjapdxVuaEqVZbA7S+2ndK4dGubBMHGQgAI2zz95/rYon25wyThzsIz+Nj3qezPbXzEWr0Y/xUn38qPsOnFkWHJZV5P9RRGve0irbPj6wQv0koB0puzpu2xejqUSJujenvdrY9lTv3lP1LY2QP8MiH+rVE0wmlrvD/ncc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785922150; c=relaxed/simple; bh=A7rKcA2h6eqZuojQEAg5gwuFspwZiVWsnoU0Y3AQDJQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YKKOJr0FeZ8CruEzqCFO4BAthfOPVg968qlUF5KCnncWBvLRad7Lcl7x80Blzp3XMu9Q+WIFEdLnKaFeRtV/gXbdhMXWQF8HAUGVW6omTdyKiA8X+eaxP2FHixdvipe6biVsgSn2zB+V2ZfUPsXeSRBRnPddyqAnsOctq2s7STQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O4soNZNB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="O4soNZNB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 207561F000E9; Wed, 5 Aug 2026 09:29:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785922149; bh=oRyIleA0QGFz+qX0HHV60JJZ/Z0/YRsU886/+NfcGc8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=O4soNZNBpt5mbd8Bae3u8szcsEfQ396/Wip2ZLHe63VSCXFUCckBx8yqXY/0qjqfh RT6fkDdykdt03lg7txmufXTtrCWju0b1a0csnLnw20wHo/pCDRxRH92+BUubAu7nMT 2tJuo71fIsKoyDRRMaKPK8kfRG0WLEbHGGbZTAG+ZYMwaR1TRtTZG3ZNQYpXq0JGN4 1cJw/HqmO5x3rQXd+eOe7Uet4ve/VYnEMuXuB8a/6YwqjURk3oymYX0WNg5SqpK4Ko HtCnkydR9b7yS+km2mUxlHGAGdjcNu08zWmNz9MxA99ZTIestkfj9U6/A31xuZxdJV xiVnCeDonxxjQ== From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: bpf@vger.kernel.org, Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , Quentin Monnet , Tao Chen , STAR Labs SG , Arnaud Lecomte Subject: [PATCHv4 bpf-next 02/12] bpf: Factor stackid_fastpath function from __bpf_get_stackid Date: Wed, 5 Aug 2026 11:28:33 +0200 Message-ID: <20260805092843.516315-3-jolsa@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260805092843.516315-1-jolsa@kernel.org> References: <20260805092843.516315-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. The -ENOENT error is the fall through to the slow path. Signed-off-by: Jiri Olsa --- kernel/bpf/stackmap.c | 43 ++++++++++++++++++++++++++++--------------- 1 file 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)) -- 2.54.0