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 <rost...@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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