From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752966Ab3GAHXY (ORCPT ); Mon, 1 Jul 2013 03:23:24 -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 S1752911Ab3GAHXV (ORCPT ); Mon, 1 Jul 2013 03:23:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,972,1363158000"; d="scan'208";a="362388549" 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 7/7] perf, x86: Discard zero length call entries in LBR call stack Date: Mon, 1 Jul 2013 15:23:07 +0800 Message-Id: <1372663387-11754-8-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1372663387-11754-1-git-send-email-zheng.z.yan@intel.com> References: <1372663387-11754-1-git-send-email-zheng.z.yan@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Yan, Zheng" "Zero length call" uses the attribute of the call instruction to push the immediate instruction pointer on to the stack and then pops off that address into a register. This is accomplished without any matching return instruction. It confuses the hardware and make the recorded call stack incorrect. Try fixing the call stack by discarding zero length call entries. Signed-off-by: Yan, Zheng --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 3146fb5..b1617d8 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -94,7 +94,8 @@ enum { X86_BR_ABORT = 1 << 12,/* transaction abort */ X86_BR_IN_TX = 1 << 13,/* in transaction */ X86_BR_NO_TX = 1 << 14,/* not in transaction */ - X86_BR_CALL_STACK = 1 << 15,/* call stack */ + X86_BR_ZERO_CALL = 1 << 15,/* zero length call */ + X86_BR_CALL_STACK = 1 << 16,/* call stack */ }; #define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL) @@ -111,13 +112,15 @@ enum { X86_BR_JMP |\ X86_BR_IRQ |\ X86_BR_ABORT |\ - X86_BR_IND_CALL) + X86_BR_IND_CALL |\ + X86_BR_ZERO_CALL) #define X86_BR_ALL (X86_BR_PLM | X86_BR_ANY) #define X86_BR_ANY_CALL \ (X86_BR_CALL |\ X86_BR_IND_CALL |\ + X86_BR_ZERO_CALL |\ X86_BR_SYSCALL |\ X86_BR_IRQ |\ X86_BR_INT) @@ -650,6 +653,12 @@ static int branch_type(unsigned long from, unsigned long to, int abort) ret = X86_BR_INT; break; case 0xe8: /* call near rel */ + insn_get_immediate(&insn); + if (insn.immediate1.value == 0) { + /* zero length call */ + ret = X86_BR_ZERO_CALL; + break; + } case 0x9a: /* call far absolute */ ret = X86_BR_CALL; break; -- 1.8.1.4