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Re: [RFC 2/3] arm64: refactor save_stack_trace()

From AKASHI Takahiro <takahiro.akashi@linaro.org>
Newsgroups linux.kernel
Subject Re: [RFC 2/3] arm64: refactor save_stack_trace()
Date 2015-07-16 03:10 +0200
Message-ID <pMFQu-86K-9@gated-at.bofh.it> (permalink)
References (5 earlier) <pMl5n-2RI-1@gated-at.bofh.it> <pMtmi-6p4-15@gated-at.bofh.it> <pMwka-2xg-3@gated-at.bofh.it> <pMxzz-4yf-5@gated-at.bofh.it> <pMFdM-781-15@gated-at.bofh.it>
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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 <rostedt@goodmis.org> 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 */

  #ifndef __ASSEMBLY__
  #include <linux/compat.h>
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);
-- 
1.7.9.5


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Thread

[RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-07-13 07:40 +0200
  Re: [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-07-15 02:30 +0200
    Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-15 05:00 +0200
      Re: [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-07-15 13:50 +0200
        Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-15 17:00 +0200
          Re: [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-07-16 02:30 +0200
            Re: [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-07-16 03:10 +0200
              Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 03:40 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Will Deacon <will.deacon@arm.com> - 2015-07-17 12:50 +0200
              Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 16:30 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Jungseok Lee <jungseoklee85@gmail.com> - 2015-07-16 17:10 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 17:40 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Jungseok Lee <jungseoklee85@gmail.com> - 2015-07-16 18:00 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 22:30 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 18:20 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Mark Rutland <mark.rutland@arm.com> - 2015-07-17 14:50 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-17 15:00 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-17 15:10 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Jungseok Lee <jungseoklee85@gmail.com> - 2015-07-17 16:30 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-17 16:50 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Jungseok Lee <jungseoklee85@gmail.com> - 2015-07-17 17:00 +0200
              Re: [RFC 2/3] arm64: refactor save_stack_trace() Mark Rutland <mark.rutland@arm.com> - 2015-07-16 16:30 +0200
                Re: [RFC 2/3] arm64: refactor save_stack_trace() Steven Rostedt <rostedt@goodmis.org> - 2015-07-16 16:40 +0200
              Re: [RFC 2/3] arm64: refactor save_stack_trace() Jungseok Lee <jungseoklee85@gmail.com> - 2015-07-17 16:40 +0200

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