Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754104AbdFSSjG (ORCPT + 2 others); Mon, 19 Jun 2017 14:39:06 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:52699 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753593AbdFSSjA (ORCPT ); Mon, 19 Jun 2017 14:39:00 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Josh Poimboeuf , "Rafael J . Wysocki" , Willy Tarreau Subject: [PATCH 3.10 211/268] ACPI: Fix incompatibility with mcount-based function graph tracing Date: Mon, 19 Jun 2017 20:31:50 +0200 Message-Id: <1497897167-14556-212-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1497897167-14556-1-git-send-email-w@1wt.eu> References: <1497897167-14556-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Josh Poimboeuf commit 61b79e16c68d703dde58c25d3935d67210b7d71b upstream. Paul Menzel reported a warning: WARNING: CPU: 0 PID: 774 at /build/linux-ROBWaj/linux-4.9.13/kernel/trace/trace_functions_graph.c:233 ftrace_return_to_handler+0x1aa/0x1e0 Bad frame pointer: expected f6919d98, received f6919db0 from func acpi_pm_device_sleep_wake return to c43b6f9d The warning means that function graph tracing is broken for the acpi_pm_device_sleep_wake() function. That's because the ACPI Makefile unconditionally sets the '-Os' gcc flag to optimize for size. That's an issue because mcount-based function graph tracing is incompatible with '-Os' on x86, thanks to the following gcc bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109 I have another patch pending which will ensure that mcount-based function graph tracing is never used with CONFIG_CC_OPTIMIZE_FOR_SIZE on x86. But this patch is needed in addition to that one because the ACPI Makefile overrides that config option for no apparent reason. It has had this flag since the beginning of git history, and there's no related comment, so I don't know why it's there. As far as I can tell, there's no reason for it to be there. The appropriate behavior is for it to honor CONFIG_CC_OPTIMIZE_FOR_{SIZE,PERFORMANCE} like the rest of the kernel. Reported-by: Paul Menzel Signed-off-by: Josh Poimboeuf Acked-by: Steven Rostedt (VMware) Signed-off-by: Rafael J. Wysocki Signed-off-by: Willy Tarreau --- drivers/acpi/Makefile | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 97c949a..2af5b5a 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -2,7 +2,6 @@ # Makefile for the Linux ACPI interpreter # -ccflags-y := -Os ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT # -- 2.8.0.rc2.1.gbe9624a