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 EBD4A346AC0 for ; Wed, 5 Aug 2026 09:29:57 +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=1785922199; cv=none; b=uvV7CI7d9rBTRhrtRfGtcwtZWR/ZVUap8mkSXemeRULwREY8zUHLXQA2Q+UXkcRyiNOgfgDHahplSAlEQhVQfPg1wZoEUTXF5ZkguQuL8W4Ti/pE/DXodXKKttz53pJSPQ/Eto2lBrR5fborMnx3LjzI6+G6kuPXqbvz8PJ//o4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785922199; c=relaxed/simple; bh=NM0CCFQUCiHhsVQH9bBGQVL885iap3Mwz1SYGNNGjY4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pR+UEf6hWFop+q86FaqeIyEOb+GDK1qHq9/fyoYwo8zK8Cw7f/ol/4Qg6lmY5Fmx15WEEcAFdf5DMksOSVhsMAn1PLWbGdR0n0huAC/a8oPuYRBeMFyqBCXiB/9Ppy9uoIo7Fy9+XmMO91d5iIdzC4dfON418rIySLC+8P81uG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bYZ8LKiI; 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="bYZ8LKiI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA0621F00A3A; Wed, 5 Aug 2026 09:29:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785922197; bh=XHj5Ye397xeC2DSzEpy1uMTkvozUF1c20AbZUwhOk78=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bYZ8LKiIc4AchVxul9EKe9YRDGc9KIW+I0904D8/2tRA9iIC+zQaKMpNKe3NelDHH zZZAUZ41ttQ2Pj2rRAG31dFvrjDjhLCkRIntkpKXEsWTD3kJWc0z6zW1QvtkNg4+2U 7YAXu0yuKRl2KKApDkXOEbtyKo0I+lpoaMAcJDegbX6BquN5ymzoDBrjwh+W8uYhoq rkh5wKVjIJZkQPmVnfIPvms0fAULcZL9rRI/QscZLxe26hH1Y+7UkvzduxVkfTgPkA XyC2pQGXrAdNMvTUPS1Gc7UOc8INnomQQu/jRoPJeK+D18Jz9tlQ2jPM/uUqS/kyQM BOXUH61GsjXPg== 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 07/12] bpf: Factor callchain_finalize function from __bpf_get_stack Date: Wed, 5 Aug 2026 11:28:38 +0200 Message-ID: <20260805092843.516315-8-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 callchain_finalize function calls the build-id retrieval (if needed) and zeroes the buffer. This makes things easier for preemption fix in following change. Signed-off-by: Jiri Olsa --- kernel/bpf/stackmap.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index ee9905d67b8e..cdeb6c2e50da 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -764,16 +764,31 @@ static u32 callchain_store(struct perf_callchain_entry *trace, void *buf, return trace_nr; } +static long callchain_finalize(void *buf, u32 size, u32 trace_nr, u32 elem_size, + u64 flags, bool may_fault) +{ + bool user_build_id = flags & BPF_F_USER_BUILD_ID; + bool user = flags & BPF_F_USER_STACK; + u32 copy_len = trace_nr * elem_size; + + if (user_build_id) + stack_map_get_build_id_offset(buf, trace_nr, user, may_fault); + + if (size > copy_len) + memset(buf + copy_len, 0, size - copy_len); + return copy_len; +} + static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, struct perf_callchain_entry *trace_in, void *buf, u32 size, u64 flags, bool may_fault) { - u32 trace_nr, copy_len, elem_size, max_depth; bool user_build_id = flags & BPF_F_USER_BUILD_ID; bool crosstask = task && task != current; u32 skip = flags & BPF_F_SKIP_FIELD_MASK; bool user = flags & BPF_F_USER_STACK; struct perf_callchain_entry *trace; + u32 trace_nr, elem_size, max_depth; bool kernel = !user; int err = -EINVAL; @@ -821,18 +836,12 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, } trace_nr = callchain_store(trace, buf, elem_size, flags); - copy_len = trace_nr * elem_size; /* trace should not be dereferenced after this point */ if (may_fault) rcu_read_unlock(); - if (user_build_id) - stack_map_get_build_id_offset(buf, trace_nr, user, may_fault); - - if (size > copy_len) - memset(buf + copy_len, 0, size - copy_len); - return copy_len; + return callchain_finalize(buf, size, trace_nr, elem_size, flags, may_fault); err_fault: err = -EFAULT; -- 2.54.0