From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786Ab3GAHXM (ORCPT ); Mon, 1 Jul 2013 03:23:12 -0400 Received: from mga02.intel.com ([134.134.136.20]:6666 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752140Ab3GAHXL (ORCPT ); Mon, 1 Jul 2013 03:23:11 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,972,1363158000"; d="scan'208";a="362388499" From: "Yan, Zheng" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, a.p.zijlstra@chello.nl, eranian@google.com, andi@firstfloor.org, "Yan, Zheng" Subject: [PATCH v2 0/7] perf, x86: Haswell LBR call stack support Date: Mon, 1 Jul 2013 15:23:00 +0800 Message-Id: <1372663387-11754-1-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.8.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Yan, Zheng" Haswell has a new feature that utilizes the existing Last Branch Record facility to record call chains. When the feature is enabled, function call will be collected as normal, but as return instructions are executed the last captured branch record is popped from the on-chip LBR registers. The LBR call stack facility can help perf to get call chains of progam without frame pointer. When perf tool requests PERF_SAMPLE_CALLCHAIN + PERF_SAMPLE_BRANCH_USER, this feature is dynamically enabled by default. This feature can be disabled/enabled through an attribute file in the cpu pmu sysfs directory. The LBR call stack has following known limitations 1. Zero length calls are not filtered out by hardware 2. Exception handing such as setjmp/longjmp will have calls/returns not match 3. Pushing different return address onto the stack will have calls/returns not match These patches are based upon tip/perf/core Regards Yan, Zheng --- Changes since v1 - more comments for why FREEZE_LBRS_ON_PMI does not work - don't save/restore LBR during context switches if LBR are used by CPU events - change mode of /sys/devices/cpu/lbr_callstack to 0644