Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757934AbbGQOib (ORCPT ); Fri, 17 Jul 2015 10:38:31 -0400 Received: from mail-pd0-f173.google.com ([209.85.192.173]:35712 "EHLO mail-pd0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbbGQOi3 convert rfc822-to-8bit (ORCPT ); Fri, 17 Jul 2015 10:38:29 -0400 Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace() Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: text/plain; charset=windows-1252 From: Jungseok Lee In-Reply-To: <55A862C0.4040101@linaro.org> Date: Fri, 17 Jul 2015 23:38:28 +0900 Cc: Steven Rostedt , catalin.marinas@arm.com, will.deacon@arm.com, olof@lixom.net, broonie@kernel.org, david.griego@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <10104998-CA54-4150-9228-2ED8C327911D@gmail.com> References: <1436765375-7119-1-git-send-email-takahiro.akashi@linaro.org> <1436765375-7119-3-git-send-email-takahiro.akashi@linaro.org> <20150714093154.4d73e551@gandalf.local.home> <55A5A75A.1060401@linaro.org> <20150714225105.6c1e4f15@gandalf.local.home> <55A646EE.6030402@linaro.org> <20150715105536.42949ea9@gandalf.local.home> <20150715121337.3b31aa84@gandalf.local.home> <55A6FA82.9000901@linaro.org> <55A703F3.8050203@linaro.org> <55A862C0.4040101@linaro.org> To: AKASHI Takahiro X-Mailer: Apple Mail (2.1283) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3692 Lines: 120 On Jul 17, 2015, at 11:04 AM, AKASHI Takahiro wrote: > Jungseok, > > Thank you for your testing and reviews. You're welcome. > On 07/16/2015 10:29 PM, Jungseok Lee wrote: >> On Jul 16, 2015, at 10:08 AM, AKASHI Takahiro wrote: >> >> Hi, AKASHI >> >>> On 07/16/2015 09:27 AM, AKASHI Takahiro wrote: >>>> On 07/16/2015 01:13 AM, Steven Rostedt wrote: >>>>> On Wed, 15 Jul 2015 10:55:36 -0400 >>>>> Steven Rostedt wrote: >>>>> >>>>> >>>>>> I'll take a look at it and try to clean up the code. >>>>> >>>>> Does the following patch make sense for you? >>>> >>>> Looks nice. The patch greatly simplifies changes on arm64 side. >>> >>> As follows: >>> >>> - Takahiro AKASHI >>> >>> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h >>> index c5534fa..868d6f1 100644 >>> --- a/arch/arm64/include/asm/ftrace.h >>> +++ b/arch/arm64/include/asm/ftrace.h >>> @@ -15,6 +15,7 @@ >>> >>> #define MCOUNT_ADDR ((unsigned long)_mcount) >>> #define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE >>> +#define FTRACE_STACK_FRAME_OFFSET 4 /* sync it up with stacktrace.c */ > > Well, > #define FTRACE_STACK_FRAME_OFFSET AARCH64_INSN_SIZE > might be better. Agree. > >> How about binding it to -4 in unwind_frame function? > > Do you mean like this? > In unwind_frame(), > frame->pc = *(unsigned long*)(fp + 8) - AARCH64_INSN_SIZE; Exactly. > >> IMHO, it would help other developers trying to change stack trace code >> be aware of this stack tracer feature. >> >>> #ifndef __ASSEMBLY__ >>> #include >>> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h >>> index 1da6029..2c1bf7d 100644 >>> --- a/include/linux/ftrace.h >>> +++ b/include/linux/ftrace.h >>> @@ -260,6 +260,13 @@ static inline void ftrace_kill(void) { } >>> #endif /* CONFIG_FUNCTION_TRACER */ >>> >>> #ifdef CONFIG_STACK_TRACER >>> +/* >>> + * the offset value to add to return address from save_stack_trace() >>> + */ >>> +#ifndef FTRACE_STACK_FRAME_OFFSET >>> +#define FTRACE_STACK_FRAME_OFFSET 0 >>> +#endif >>> + >>> extern int stack_tracer_enabled; >>> int >>> stack_trace_sysctl(struct ctl_table *table, int write, >>> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c >>> index 9384647..c5b9748 100644 >>> --- a/kernel/trace/trace_stack.c >>> +++ b/kernel/trace/trace_stack.c >>> @@ -105,7 +105,7 @@ check_stack(unsigned long ip, unsigned long *stack) >>> >>> /* Skip over the overhead of the stack tracer itself */ >>> for (i = 0; i < max_stack_trace.nr_entries; i++) { >>> - if (stack_dump_trace[i] == ip) >>> + if ((stack_dump_trace[i] + FTRACE_STACK_FRAME_OFFSET) == ip) >>> break; >>> } >>> >>> @@ -131,7 +131,8 @@ check_stack(unsigned long ip, unsigned long *stack) >>> p = start; >>> >>> for (; p < top && i < max_stack_trace.nr_entries; p++) { >>> - if (*p == stack_dump_trace[i]) { >>> + if (*p == (stack_dump_trace[i] >>> + + FTRACE_STACK_FRAME_OFFSET)) { >>> stack_dump_trace[x] = stack_dump_trace[i++]; >>> this_size = stack_dump_index[x++] = >>> (top - p) * sizeof(unsigned long); >>> -- >> >> I've prepared a kernel with the following patches and reviewed them. >> >> 1) Steve's clean up patch >> 2) This patch >> 3) [RFC 2/3] >> >> AFAIU, [RFC 3/3] is not needed any more thanks to Steve's patch. > > We don't need [2/3]. Okay. So, I've played a kernel including Steve's latest patch and only [1/3]. Best Regards Jungseok Lee-- 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/