From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 186AC1AF0B1; Tue, 15 Oct 2024 13:08:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728997712; cv=none; b=rZghQC/61Ty6iadtU1xOLBXcv/W7iQ6JCoRIL9sX35jr/tvx2a4kftE/LyHQXbvvvnyWHkfXL97d58q6un7NJfaD3radF9rOXjL25CcASsJ5NsEkOzb91GAdjrZTtbkyYxb+HMm3qP1GF8uRiJipm8kelMi9gYVPec3YNkSeJrs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728997712; c=relaxed/simple; bh=Wv2b1rwKVwowNJfF8LveIrf4IcV8I41mR1op2ZW/MeM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J11rJqI4ROoL9bK54J78JS8IEDEbhAdv8Pb9F3y+fccr7/pk7b46aAISSOZPXdaC/XSPf9guCjNF/Bq4vD/Bb++MiyE+yUi00qkoMSn+P0OlH/p8CVtnB8N6fKPN70wyID4e7ybbZqKUShwPsiRxAJ/I+V+mxf4L2ZhBqQNLBDo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T7eIhZ/F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="T7eIhZ/F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 762EDC4CEC6; Tue, 15 Oct 2024 13:08:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728997711; bh=Wv2b1rwKVwowNJfF8LveIrf4IcV8I41mR1op2ZW/MeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T7eIhZ/FfEDYxOm0nAYFrySh7RqFNChkmXAVcjLvhHAw3xHeGBpBMJjud85y4nMhI UMhPiNSCdnGnUtdidXiyC79qRJ2s9lSp+Dv7TGbuqJdSUTwNqvLKZlCvtTIN9LZ9JB uQtXfqM9bVQQjKEz5dRPCMnd78Qp9QbKf4Up+xk4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Adrian Hunter , "Peter Zijlstra (Intel)" Subject: [PATCH 5.10 236/518] perf/x86/intel/pt: Fix sampling synchronization Date: Tue, 15 Oct 2024 14:42:20 +0200 Message-ID: <20241015123926.102344718@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015123916.821186887@linuxfoundation.org> References: <20241015123916.821186887@linuxfoundation.org> User-Agent: quilt/0.67 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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Hunter commit d92792a4b26e50b96ab734cbe203d8a4c932a7a9 upstream. pt_event_snapshot_aux() uses pt->handle_nmi to determine if tracing needs to be stopped, however tracing can still be going because pt->handle_nmi is set to zero before tracing is stopped in pt_event_stop, whereas pt_event_snapshot_aux() requires that tracing must be stopped in order to copy a sample of trace from the buffer. Instead call pt_config_stop() always, which anyway checks config for RTIT_CTL_TRACEEN and does nothing if it is already clear. Note pt_event_snapshot_aux() can continue to use pt->handle_nmi to determine if the trace needs to be restarted afterwards. Fixes: 25e8920b301c ("perf/x86/intel/pt: Add sampling support") Signed-off-by: Adrian Hunter Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240715160712.127117-2-adrian.hunter@intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/intel/pt.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -1586,6 +1586,7 @@ static void pt_event_stop(struct perf_ev * see comment in intel_pt_interrupt(). */ WRITE_ONCE(pt->handle_nmi, 0); + barrier(); pt_config_stop(event); @@ -1637,11 +1638,10 @@ static long pt_event_snapshot_aux(struct return 0; /* - * Here, handle_nmi tells us if the tracing is on + * There is no PT interrupt in this mode, so stop the trace and it will + * remain stopped while the buffer is copied. */ - if (READ_ONCE(pt->handle_nmi)) - pt_config_stop(event); - + pt_config_stop(event); pt_read_offset(buf); pt_update_head(pt); @@ -1653,11 +1653,10 @@ static long pt_event_snapshot_aux(struct ret = perf_output_copy_aux(&pt->handle, handle, from, to); /* - * If the tracing was on when we turned up, restart it. - * Compiler barrier not needed as we couldn't have been - * preempted by anything that touches pt->handle_nmi. + * Here, handle_nmi tells us if the tracing was on. + * If the tracing was on, restart it. */ - if (pt->handle_nmi) + if (READ_ONCE(pt->handle_nmi)) pt_config_start(event); return ret;