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 59F30373BF2; Sat, 12 Sep 2026 10:19:13 +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=1789208354; cv=none; b=hfgUaOh+FjAD+QsVCrNBLADFmNdloi+mXtcM0poVgREjLI3du+nTcH7P5M0QJIJC8tMRQdfM1jjPTq+AISDitiDTuMSq3gJoxKEAU0S6B99Oq93Zjs0/l9cI6fZ1NncojIzbJ4cUfsA054udDIKJtGK+P2t6houTAZMtSxAFwDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789208354; c=relaxed/simple; bh=nfuY20UEHW4BMTvexSEpia6j/3fD3y+o8u7OIsLo2qU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=knWxsrR8D/M/0rt5zuNhXCuPu/PvLW7xHcEN613IYu/zkzv40VwEjK32tk65SZxpbDkB7FQA5ioYrqNkgqipiVoxipj052JXweILL8QF25syiOrsvTW5dX58P9l7bthQgEsSbEHVsh/7oNFX+pjSArLoqxlKJaNsMUyhF2NApa0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yc18VAo0; 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="yc18VAo0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F27C1F000FF; Sat, 12 Sep 2026 10:19:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789208353; bh=JetAGvxgXWD2ouhOMZL+BqlMhqbGCpe+6RcWhtaEw/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=yc18VAo0gbVJNUz94etSEegEaqNZjfDnIED6VRFQZf/RJKKwXFwcuyGGsL092UnrO Q5K5vbX2ytrAADU9tfeECfwXnPAV0uw5Axm6TktG7rbGSNjKb2RHBmOgABVv8M/3lg DR6+wSCW9NUZOMa8KKjyaga70yoPWrHq+7Adsjc8= 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 6.18 0556/1518] perf cs-etm: Flush thread stacks after decoder reset Date: Sat, 12 Sep 2026 08:45:25 +0200 Message-ID: <20260912065636.015677972@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065623.398859879@linuxfoundation.org> References: <20260912065623.398859879@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-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 66dbead2c03bc..215414a8f61f1 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -2066,6 +2066,45 @@ 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. @@ -2088,6 +2127,12 @@ 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