linux-kernel - Re: [PATCH] ftrace/x86: Fix function graph tracer reset path

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Date:	Mon, 16 May 2016 20:52:37 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
	Borislav Petkov <bp@...e.de>, "H.J. Lu" <hjl.tools@...il.com>
Subject: Re: [PATCH] ftrace/x86: Fix function graph tracer reset path

On Mon, 16 May, at 09:58:33AM, Steven Rostedt wrote:
> 
> Can we solve this by doing the same thing it did for the kernel?
> 
> -- Steve
> 
> diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
> index ed48a9f465f8..e13a695c3084 100644
> --- a/arch/x86/kernel/mcount_64.S
> +++ b/arch/x86/kernel/mcount_64.S
> @@ -182,7 +182,8 @@ GLOBAL(ftrace_graph_call)
>  	jmp ftrace_stub
>  #endif
>  
> -GLOBAL(ftrace_stub)
> +/* This is weak to keep gas from relaxing the jumps */
> +WEAK(ftrace_stub)
>  	retq
>  END(ftrace_caller)
  
Works for me.

Tested-by: Matt Fleming <matt@...eblueprint.co.uk>