From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 14 Mar 2014 10:09:14 +0000 Subject: [PATCH v6 6/7] arm64: ftrace: Add CALLER_ADDRx macros In-Reply-To: <532270BE.6000409@linaro.org> 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> <532270BE.6000409@linaro.org> Message-ID: <20140314100914.GD13541@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Mar 14, 2014 at 03:00:14AM +0000, AKASHI Takahiro wrote: > On 03/14/2014 12:54 AM, 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? > > arm64 selects ARCH_WANT_FRAME_POINTERS, then FRAME_POINTER is on (lib/Kconfig.debug) > and so -fno-omit-frame-pointer is appended (${TOP}/Makefile). > (stacktrace.c also assumes FRAME_POINTER.) > > Do you think I should remove the comment above? Yes please, it sounds like everything is taken care of automatically, so there's no need to scare people in the commit message! > >> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > >> index ed5c448..c44c4b1 100644 > >> --- a/arch/arm64/include/asm/ftrace.h > >> +++ b/arch/arm64/include/asm/ftrace.h > >> @@ -18,6 +18,7 @@ > >> > >> #ifndef __ASSEMBLY__ > >> extern void _mcount(unsigned long); > >> +extern void *return_address(unsigned int); > >> > >> struct dyn_arch_ftrace { > >> /* No extra data needed for arm64 */ > >> @@ -33,6 +34,16 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) > >> */ > >> return addr; > >> } > >> -#endif /* __ASSEMBLY__ */ > >> + > >> +#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? > > I think I understand what you mean, and will try to post a separate RFC, > but I also want to hold off this change on this patch since such a change > may raise a small controversy from other archs' maintainers. I don't see anything controversial here, but ok. Steve already posted something you can get started with. Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753923AbaCNKMM (ORCPT ); Fri, 14 Mar 2014 06:12:12 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:46416 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752091AbaCNKML (ORCPT ); Fri, 14 Mar 2014 06:12:11 -0400 Date: Fri, 14 Mar 2014 10:09:14 +0000 From: Will Deacon To: AKASHI Takahiro Cc: "rostedt@goodmis.org" , "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 Message-ID: <20140314100914.GD13541@arm.com> 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> <532270BE.6000409@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <532270BE.6000409@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 14, 2014 at 03:00:14AM +0000, AKASHI Takahiro wrote: > On 03/14/2014 12:54 AM, 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? > > arm64 selects ARCH_WANT_FRAME_POINTERS, then FRAME_POINTER is on (lib/Kconfig.debug) > and so -fno-omit-frame-pointer is appended (${TOP}/Makefile). > (stacktrace.c also assumes FRAME_POINTER.) > > Do you think I should remove the comment above? Yes please, it sounds like everything is taken care of automatically, so there's no need to scare people in the commit message! > >> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > >> index ed5c448..c44c4b1 100644 > >> --- a/arch/arm64/include/asm/ftrace.h > >> +++ b/arch/arm64/include/asm/ftrace.h > >> @@ -18,6 +18,7 @@ > >> > >> #ifndef __ASSEMBLY__ > >> extern void _mcount(unsigned long); > >> +extern void *return_address(unsigned int); > >> > >> struct dyn_arch_ftrace { > >> /* No extra data needed for arm64 */ > >> @@ -33,6 +34,16 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) > >> */ > >> return addr; > >> } > >> -#endif /* __ASSEMBLY__ */ > >> + > >> +#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? > > I think I understand what you mean, and will try to post a separate RFC, > but I also want to hold off this change on this patch since such a change > may raise a small controversy from other archs' maintainers. I don't see anything controversial here, but ok. Steve already posted something you can get started with. Will