Re: [PATCH -v6 05/13] tracing: enable HAVE_FUNCTION_TRACE_MCOUNT_TEST for MIPS

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Wu Zhangjin wrote:

> There is an exisiting common ftrace_test_stop_func() in
> kernel/trace/ftrace.c, which is used to check the global variable
> ftrace_trace_stop to determine whether stop the function tracing.

> This patch implepment the MIPS specific one to speedup the procedure.

> Thanks goes to Zhang Le for Cleaning it up.

> Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>

[...]

> diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
> index 0c39bc8..5dfaca8 100644
> --- a/arch/mips/kernel/mcount.S
> +++ b/arch/mips/kernel/mcount.S
> @@ -64,6 +64,10 @@
>  	.endm
>  
>  NESTED(_mcount, PT_SIZE, ra)
> +	lw	t0, function_trace_stop
> +	bnez	t0, ftrace_stub
> +	nop

1) unless .set noreorder is specified in this file, explicit nop is not needed;

2) delay slot instruction is usually denoted by adding extra space on its 
left, like this:

	bnez	t0, ftrace_stub
	 nop

WBR, Sergei