From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759744Ab3BYCDU (ORCPT ); Sun, 24 Feb 2013 21:03:20 -0500 Received: from mga03.intel.com ([143.182.124.21]:21536 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759564Ab3BYCB7 (ORCPT ); Sun, 24 Feb 2013 21:01:59 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,730,1355126400"; d="scan'208";a="205839805" 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 7/7] perf, x86: Discard zero length call entries in LBR call stack Date: Mon, 25 Feb 2013 10:01:27 +0800 Message-Id: <1361757687-5415-8-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1361757687-5415-1-git-send-email-zheng.z.yan@intel.com> References: <1361757687-5415-1-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 0cebb01..4795cfc 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_INTX = 1 << 13,/* in transaction */ X86_BR_NOTX = 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) @@ -647,6 +650,12 @@ 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; -- 1.7.11.7