[PATCH] ftrace/x86: Add comment on static function tracing

[PATCH] ftrace/x86: Add comment on static function tracing

[Namhyung Kim]

There was a confusion between update_ftrace_function() and static
function tracing trampoline regarding 3rd parameter (ftrace_ops).
Add a comment for clarification.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 arch/x86/kernel/mcount_64.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 94ea120fa21f..87e1762e2bca 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -278,6 +278,12 @@ GLOBAL(ftrace_stub)
 	/* save_mcount_regs fills in first two parameters */
 	save_mcount_regs
 
+	/*
+	 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+	 * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
+	 * ip and parent ip are used and the list function is called when
+	 * function tracing is enabled.
+	 */
 	call   *ftrace_trace_function
 
 	restore_mcount_regs
-- 
2.6.2

Re: [PATCH] ftrace/x86: Add comment on static function tracing

[Steven Rostedt]

On Tue, 17 Nov 2015 09:43:24 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> There was a confusion between update_ftrace_function() and static
> function tracing trampoline regarding 3rd parameter (ftrace_ops).
> Add a comment for clarification.
> 
> Suggested-by: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  arch/x86/kernel/mcount_64.S | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
> index 94ea120fa21f..87e1762e2bca 100644
> --- a/arch/x86/kernel/mcount_64.S
> +++ b/arch/x86/kernel/mcount_64.S
> @@ -278,6 +278,12 @@ GLOBAL(ftrace_stub)
>  	/* save_mcount_regs fills in first two parameters */
>  	save_mcount_regs
>  
> +	/*
> +	 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
> +	 * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
> +	 * ip and parent ip are used and the list function is called when
> +	 * function tracing is enabled.
> +	 */
>  	call   *ftrace_trace_function
>  
>  	restore_mcount_regs

[tip:x86/urgent] x86/ftrace: Add comment on static function tracing

[tip-bot for Namhyung Kim]

Commit-ID:  112677d683d31ebd6a8e8b02e0620ae512354b2d
Gitweb:     http://git.kernel.org/tip/112677d683d31ebd6a8e8b02e0620ae512354b2d
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Tue, 17 Nov 2015 09:43:24 +0900
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 19 Nov 2015 11:07:49 +0100

x86/ftrace: Add comment on static function tracing

There was a confusion between update_ftrace_function() and static
function tracing trampoline regarding 3rd parameter (ftrace_ops).
Add a comment for clarification.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1447721004-2551-1-git-send-email-namhyung@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/mcount_64.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 94ea120..87e1762 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -278,6 +278,12 @@ trace:
 	/* save_mcount_regs fills in first two parameters */
 	save_mcount_regs
 
+	/*
+	 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+	 * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
+	 * ip and parent ip are used and the list function is called when
+	 * function tracing is enabled.
+	 */
 	call   *ftrace_trace_function
 
 	restore_mcount_regs