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 281EF3A1691 for ; Mon, 3 Aug 2026 21:03:06 +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=1785790987; cv=none; b=RdtVI0VZuFoLw0Qdxs0/f621fjqz6iy8phiSexNo+LBGXk/Xx7pt8JUUBbb+F5DdEtAVA0eQan15RoDVY6tPQQUdAICOTMAZ4xG0Ol6h0SEGGH2JF1dUyb7xzVnzRNqJ99YepP8HmFvyBbmg/ySL4M3r9tWsbUSWQhB+p4ds5jY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785790987; c=relaxed/simple; bh=NM0CCFQUCiHhsVQH9bBGQVL885iap3Mwz1SYGNNGjY4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kV7bjxH6kf6HaY4QPnory1c75hbmYPGMbzf2rDphwxfnu8E7u3vq+trNpFkn+r3S/QvrpFV9VPZ41hBaJfItx+2wXrnhXodweLqIVazC4alnSCsP4fIhOc/idxpn+Azjgoqp1G0ef97/NDo//a1Ha9GF5yhI/YYPV1zpDX+urm4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RwCic4Qe; 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="RwCic4Qe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A9ED1F000E9; Mon, 3 Aug 2026 21:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785790986; bh=XHj5Ye397xeC2DSzEpy1uMTkvozUF1c20AbZUwhOk78=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RwCic4QeNs34Xus6Zc/vwYEckfFAl5nDirQP9lh2GyaTw+o9l+vyw3jg9w3wHXOGU RxVvFW4k0vCJ0OsBdCI9hIzwYix4+jA2yxW95yE2aFdLRgGSwrjdamrzG6pcm5+u3b wc48z6+LcdSN3+3+vEb3JoklqgQwMJmQPvSQCaru0rUEJGjkEeGNWKZg8WzDrLU4nM NZXVagWq9N8eFzPA2REkUco9brjG9ptcPdXcIBWjwthDcYMXg2bxNHi1tMOgfPMXZ9 rOrF4zzsiKl3DSv7H3W4c+zC+sgEebfwDvxv/NsJfSSjjjL+ZI6/NEmABLX/iaDLJx LGd23tzJFv68g== 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: [PATCHv3 bpf-next 07/12] bpf: Factor callchain_finalize function from __bpf_get_stack Date: Mon, 3 Aug 2026 23:01:44 +0200 Message-ID: <20260803210149.296496-8-jolsa@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260803210149.296496-1-jolsa@kernel.org> References: <20260803210149.296496-1-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