Re: [PATCH] ftrace/x86: Fix missing ops arg on static function tracing

[Steven Rostedt <rostedt@goodmis.org>]

On Sat, 14 Nov 2015 18:32:28 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> The commit f1ab00af816e ("ftrace/x86: Get rid of ftrace_caller_setup")
> moved code that loads ftrace_ops into 3rd parameter but it missed to do
> for static tracing.
> 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  arch/x86/kernel/mcount_64.S | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
> index 94ea120fa21f..6c1ccf9e5427 100644
> --- a/arch/x86/kernel/mcount_64.S
> +++ b/arch/x86/kernel/mcount_64.S
> @@ -278,6 +278,9 @@ trace:
>  	/* save_mcount_regs fills in first two parameters */
>  	save_mcount_regs
>  
> +	/* Load the ftrace_ops into the 3rd parameter */
> +	movq function_trace_op(%rip), %rdx
> +
>  	call   *ftrace_trace_function

This isn't needed, nor will the parameter be used if added. A comment
should probably be added here instead.

/*
 * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
 * set (see include/asm/ftrace.h). Only the ip and parent ip are used
 * and the list function is called when function tracing is enabled.
 */

-- Steve

>  
>  	restore_mcount_regs