linux-kernel - Re: [PATCH] recordmcount.pl: add support for __fentry_

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Date:	Thu, 31 Oct 2013 12:09:26 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jamie Iles <jamie.iles@...cle.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] recordmcount.pl: add support for __fentry__

On Thu, 31 Oct 2013 15:59:58 +0000
Jamie Iles <jamie.iles@...cle.com> wrote:

> With gcc 4.6.0 the -mfentry feature places the function profiling call
> at the start of the function. When this is used, the call is to
> __fentry__ and not mcount.
> 
> Based on 48bb5dc6cd9d30fe0d594947563da1f8bd9abada (ftrace: Make
> recordmcount.c handle __fentry__).

Why? All current users of __fentry__ use the C version of recordmcount.
This just slows down the few archs that still use recordmcount.pl.

-- Steve

> 
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Signed-off-by: Jamie Iles <jamie.iles@...cle.com>
> ---
>  scripts/recordmcount.pl | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index a674fd5..6460fc68 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -214,7 +214,7 @@ $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
>  $weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
>  $section_regex = "Disassembly of section\\s+(\\S+):";
>  $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
> -$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
> +$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s(mcount|__fentry__)\$";
>  $section_type = '@...gbits';
>  $mcount_adjust = 0;
>  $type = ".long";

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