From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752794AbaCNEzW (ORCPT ); Fri, 14 Mar 2014 00:55:22 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:46150 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752101AbaCNEzU (ORCPT ); Fri, 14 Mar 2014 00:55:20 -0400 Message-ID: <53228BAB.7080005@linaro.org> Date: Fri, 14 Mar 2014 13:55:07 +0900 From: AKASHI Takahiro User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Steven Rostedt , Will Deacon CC: "fweisbec@gmail.com" , "mingo@redhat.com" , Catalin Marinas , "tim.bird@sonymobile.com" , "gkulkarni@caviumnetworks.com" , "dsaxena@linaro.org" , "arndb@arndb.de" , "linux-arm-kernel@lists.infradead.org" , "linaro-kernel@lists.linaro.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v6 6/7] arm64: ftrace: Add CALLER_ADDRx macros References: <1393564724-3966-1-git-send-email-takahiro.akashi@linaro.org> <1394705630-12384-1-git-send-email-takahiro.akashi@linaro.org> <1394705630-12384-7-git-send-email-takahiro.akashi@linaro.org> <20140313155415.GB25472@mudshark.cambridge.arm.com> <1394734070.26600.6.camel@pippen.local.home> In-Reply-To: <1394734070.26600.6.camel@pippen.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/14/2014 03:07 AM, Steven Rostedt wrote: > On Thu, 2014-03-13 at 15:54 +0000, Will Deacon wrote: >> On Thu, Mar 13, 2014 at 10:13:49AM +0000, AKASHI Takahiro wrote: >>> CALLER_ADDRx returns caller's address at specified level in call stacks. >>> They are used for several tracers like irqsoff and preemptoff. >>> Strange to say, however, they are refered even without FTRACE. >>> >>> Please note that this implementation assumes that we have frame pointers. >>> (which means kernel should be compiled with -fno-omit-frame-pointer.) >> >> How do you ensure that -fno-omit-frame-pointer is passed? > > Perhaps -pg does the same thing? > >>> +#define HAVE_ARCH_CALLER_ADDR >>> + >>> +#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0)) >>> +#define CALLER_ADDR1 ((unsigned long)return_address(1)) >>> +#define CALLER_ADDR2 ((unsigned long)return_address(2)) >>> +#define CALLER_ADDR3 ((unsigned long)return_address(3)) >>> +#define CALLER_ADDR4 ((unsigned long)return_address(4)) >>> +#define CALLER_ADDR5 ((unsigned long)return_address(5)) >>> +#define CALLER_ADDR6 ((unsigned long)return_address(6)) >> >> Could we change the core definitions of these macros (in linux/ftrace.h) to >> use return_address, then provide an overridable version of return_address >> that defaults to __builtin_return_address, instead of copy-pasting this >> sequence? > > We could add a new macro: > > /* All archs should have this, but we define it for consistency */ > #ifndef ftrace_return_address0 > # define ftrace_return_address0 __builtin_return_address(0) > #endif > /* Archs may use other ways for ADDR1 and beyond */ > #ifndef ftrace_return_address > # define ftrace_return_address(n) __builtin_return_address(n) > #endif > > And then have: > > #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0) > #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1)) > [...] > > And then you would only need to redefine ftrace_return_address. I'm going to create a separate RFC, including fixes for other archs. -Takahiro AKASHI > -- Steve > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Fri, 14 Mar 2014 13:55:07 +0900 Subject: [PATCH v6 6/7] arm64: ftrace: Add CALLER_ADDRx macros In-Reply-To: <1394734070.26600.6.camel@pippen.local.home> References: <1393564724-3966-1-git-send-email-takahiro.akashi@linaro.org> <1394705630-12384-1-git-send-email-takahiro.akashi@linaro.org> <1394705630-12384-7-git-send-email-takahiro.akashi@linaro.org> <20140313155415.GB25472@mudshark.cambridge.arm.com> <1394734070.26600.6.camel@pippen.local.home> Message-ID: <53228BAB.7080005@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 03/14/2014 03:07 AM, Steven Rostedt wrote: > On Thu, 2014-03-13 at 15:54 +0000, Will Deacon wrote: >> On Thu, Mar 13, 2014 at 10:13:49AM +0000, AKASHI Takahiro wrote: >>> CALLER_ADDRx returns caller's address at specified level in call stacks. >>> They are used for several tracers like irqsoff and preemptoff. >>> Strange to say, however, they are refered even without FTRACE. >>> >>> Please note that this implementation assumes that we have frame pointers. >>> (which means kernel should be compiled with -fno-omit-frame-pointer.) >> >> How do you ensure that -fno-omit-frame-pointer is passed? > > Perhaps -pg does the same thing? > >>> +#define HAVE_ARCH_CALLER_ADDR >>> + >>> +#define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0)) >>> +#define CALLER_ADDR1 ((unsigned long)return_address(1)) >>> +#define CALLER_ADDR2 ((unsigned long)return_address(2)) >>> +#define CALLER_ADDR3 ((unsigned long)return_address(3)) >>> +#define CALLER_ADDR4 ((unsigned long)return_address(4)) >>> +#define CALLER_ADDR5 ((unsigned long)return_address(5)) >>> +#define CALLER_ADDR6 ((unsigned long)return_address(6)) >> >> Could we change the core definitions of these macros (in linux/ftrace.h) to >> use return_address, then provide an overridable version of return_address >> that defaults to __builtin_return_address, instead of copy-pasting this >> sequence? > > We could add a new macro: > > /* All archs should have this, but we define it for consistency */ > #ifndef ftrace_return_address0 > # define ftrace_return_address0 __builtin_return_address(0) > #endif > /* Archs may use other ways for ADDR1 and beyond */ > #ifndef ftrace_return_address > # define ftrace_return_address(n) __builtin_return_address(n) > #endif > > And then have: > > #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0) > #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1)) > [...] > > And then you would only need to redefine ftrace_return_address. I'm going to create a separate RFC, including fixes for other archs. -Takahiro AKASHI > -- Steve > >