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 6BDE238656D; Sat, 12 Sep 2026 18:54:42 +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=1789239283; cv=none; b=j4sDXVDHIeuZkSo1/RhKulb1+aaLRBqPEtVk5fDqXCDHd5M2DsAK5OaBh19zqdxcwWBrwJ+aPbTWGm9sv0fgDWIo2+2lCxx7fjxrMjgN1MKjs7y2EzNDuJZwd+cJIAgYNnbduJ2QgTbQi4P+Hm07Rd3Hw0K2lLxoXmJcq8wR9Ko= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789239283; c=relaxed/simple; bh=DcHq/A7m+hDORcb4gfbubz0mbPBgMCoeobfISxIBsFM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MZcwIm2rM5ZErY2SVbN99yUg0Z/mz4WkehqqZS0WuORv0VObX+Zb6ikgpBB5nVaP9HMY4lSZ4nN69FFh0Wzghnkem87q4DFH+R3U0ppK1j78lS5nHiSR36wit+hduM4BMM0adwElS+awNzxQVgL/F0XOUgsHVYbHV+Fw8YqvVVU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EvLzvLhC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EvLzvLhC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40C6A1F000FF; Sat, 12 Sep 2026 18:54:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789239282; bh=Ov3SD8xuZX6duYL3hv+VRHp/bF23wrAv5Vcb78wxOJM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EvLzvLhCVavKTPRmwn3brIYFFHhSi0TsEeQF8MjIvvYh46ADgXPLQe9pN8aTzatJa EamUnNiGAf31T1clZmPEbbi4FgzcTxEwP10vhBUtsia8LP6PZE4/+FH3AyT+wVTvw8 0AcNTDCBf6FeV0rYnThmVGsInIKPjpNSGzNai3hY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, James Clark , Leo Yan , Namhyung Kim , Sasha Levin Subject: [PATCH 5.15 590/935] perf cs-etm: Flush thread stacks after decoder reset Date: Sat, 12 Sep 2026 09:00:20 +0200 Message-ID: <20260912065540.373054233@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Leo Yan [ Upstream commit ea5075e3776846d4941dddf1549426ebd3feb81f ] Perf resets the CoreSight decoder when moving to a new AUX trace buffer, this causes trace discontinunity globally. For callchain synthesis, keeping thread-stack state after decoder reset can leave stale call/return history attached to threads that are decoded later, producing incorrect synthesized callchains. Flush all host thread stacks after a decoder reset. When virtualization is present, flush the guest thread stacks as well. Reviewed-by: James Clark Signed-off-by: Leo Yan Signed-off-by: Namhyung Kim Stable-dep-of: ec99be8a31db ("perf cs-etm: Avoid truncating AUX buffer sizes to int") Signed-off-by: Sasha Levin --- tools/perf/util/cs-etm.c | 45 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c index 6fa698186f0b6..be5a2e2d226d8 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -1637,6 +1637,45 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq, return 0; } + +static int cs_etm__flush_stack_cb(struct thread *thread, + void *data __maybe_unused) +{ + thread_stack__flush(thread); + return 0; +} + +static void cs_etm__flush_machine_stack(struct cs_etm_queue *etmq, pid_t pid) +{ + struct machine *machine; + + machine = machines__find(&etmq->etm->session->machines, pid); + if (machine) + machine__for_each_thread(machine, cs_etm__flush_stack_cb, NULL); +} + +static void cs_etm__flush_all_stack(struct cs_etm_queue *etmq) +{ + enum cs_etm_pid_fmt pid_fmt = cs_etm__get_pid_fmt(etmq); + + if (!etmq->etm->synth_opts.last_branch) + return; + + switch (pid_fmt) { + case CS_ETM_PIDFMT_CTXTID2: + /* Clear the guest stack if virtualization is supported */ + cs_etm__flush_machine_stack(etmq, DEFAULT_GUEST_KERNEL_ID); + fallthrough; + case CS_ETM_PIDFMT_CTXTID: + cs_etm__flush_machine_stack(etmq, HOST_KERNEL_ID); + break; + case CS_ETM_PIDFMT_NONE: + default: + break; + + } +} + /* * cs_etm__get_data_block: Fetch a block from the auxtrace_buffer queue * if need be. @@ -1659,6 +1698,12 @@ static int cs_etm__get_data_block(struct cs_etm_queue *etmq) ret = cs_etm_decoder__reset(etmq->decoder); if (ret) return ret; + + /* + * Since the decoder is reset, this causes a global trace + * discontinuity. Flush all thread stacks. + */ + cs_etm__flush_all_stack(etmq); } return etmq->buf_len; -- 2.53.0