Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756291Ab3IZI2i (ORCPT ); Thu, 26 Sep 2013 04:28:38 -0400 Received: from mga03.intel.com ([143.182.124.21]:23849 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756221Ab3IZI2g (ORCPT ); Thu, 26 Sep 2013 04:28:36 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,983,1371106800"; d="scan'208";a="401278485" From: "Yan, Zheng" To: linux-kernel@vger.kernel.org Cc: a.p.zijlstra@chello.nl, eranian@google.com, andi@firstfloor.org, "Yan, Zheng" Subject: [RFC PATCH 7/7] perf, x86: Discard zero length call entries in LBR call stack Date: Thu, 26 Sep 2013 16:28:13 +0800 Message-Id: <1380184093-8838-8-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1380184093-8838-1-git-send-email-zheng.z.yan@intel.com> References: <1380184093-8838-1-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 Content-Length: 2150 Lines: 66 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 7f42d25..3f9ab02 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) @@ -636,6 +639,12 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/