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 0513337E2E7; Sat, 12 Sep 2026 12:27:52 +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=1789216073; cv=none; b=tVYx2YkBFU7/KuvbWOnh1tBwl8kJ9Ehcv4+QoSPviDvLcHUzCTs3XuYouNy3OPqYyijqmLlCrbpsJTk+6Z4x0sH3CpqgsM8ookX0QYHzLdrwT1QdcYecTfBEBYzarefyx/X0u5zrj59MGcGemWUUsJrpndEM0oV6Njdg3ZTSIQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789216073; c=relaxed/simple; bh=+qP/UmUZ8KcG88KVs9RXR6m/RMCvYWDqiei5uqY9Poo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M+4lp9PRCSISEZTZWQxr2OsRBVEfdsy2a50VClVAV+BZFHnvhP+TYZl9bONfl4NXfu8lIz21l4AojrdOtB4nKUC0tcemUOih+FApOx6SqHDFx9JLsDyEMslZZdoozv6laV8tQDLxSikxFkaPiqNesagOoVqEnzysvLe5fPzvNrY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xNzgBF2T; 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="xNzgBF2T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB7F21F000FF; Sat, 12 Sep 2026 12:27:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789216071; bh=xxPTG83G3UAfJzFXM+YpXlNBnwnfnndTC3W4cAEkWPQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xNzgBF2Tugb1A1IIVnLKKykQvtUV093novjZ5c+t+6u9ye8NtJ4G5d9ViJTx8C9mV r0eRAYC/qqClktOGI39cNw0mg8kxvscLrc9lrnqOmwBFOMBP7VLV08Qnz/l/XYicnT WJFXAd3OR7pB6eNx6BTweHReD9XX9P7eByYVnrdI= 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 6.12 0663/1376] perf cs-etm: Flush thread stacks after decoder reset Date: Sat, 12 Sep 2026 08:51:29 +0200 Message-ID: <20260912065622.318493811@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.535295758@linuxfoundation.org> References: <20260912065607.535295758@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 6.12-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 29f0211324970..5b0dc7ef3a964 100644 --- a/tools/perf/util/cs-etm.c +++ b/tools/perf/util/cs-etm.c @@ -2039,6 +2039,45 @@ 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. @@ -2061,6 +2100,12 @@ 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