From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arun Sharma Subject: [PATCH] perf, x86: Disable sanity check Date: Wed, 18 Apr 2012 16:24:09 -0700 Message-ID: <1334791449-402-1-git-send-email-asharma@fb.com> Return-path: Received: from outmail005.snc4.facebook.com ([66.220.144.139]:43763 "EHLO intmgw001.snc4.facebook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751456Ab2DRXY3 (ORCPT ); Wed, 18 Apr 2012 19:24:29 -0400 Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: Arun Sharma , Ingo Molnar , Arnaldo Carvalho de Melo , Frederic Weisbecker , Mike Galbraith , Paul Mackerras , Peter Zijlstra , Stephane Eranian , Namhyung Kim , Tom Zanussi , linux-perf-users@vger.kernel.org Without this patch, applications with two different stack regions (eg: native stack vs JIT stack) get truncated callchains even when RBP chaining is present. GDB shows proper stack traces and the frame pointer chaining is intact. This patch disables the (fp < RSP) check, hoping that other checks in the code save the day for us. In our limited testing, this didn't seem to break anything. In the long term, we could potentially have userspace advise the kernel on the range of valid stack addresses, so we don't spend a lot of time unwinding from bogus addresses. Signed-off-by: Arun Sharma Cc: Ingo Molnar CC: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Mike Galbraith Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Namhyung Kim Cc: Tom Zanussi Cc: linux-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org --- arch/x86/kernel/cpu/perf_event.c | 3 --- 1 files changed, 0 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 07f46ba..87d9abd 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1596,9 +1596,6 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) if (bytes != sizeof(frame)) break; - if ((unsigned long)fp < regs->sp) - break; - perf_callchain_store(entry, frame.return_address); fp = frame.next_frame; } -- 1.7.8.4