linux-kernel - [PATCH 2/2] ftrace: Only update $offset when we update $ref

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Message-Id: <375cc28178c79bfb22c89a01f8da30d270bbfcbe.1249365713.git.matt@console-pimps.org>
Date:	Tue,  4 Aug 2009 07:06:41 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	linux-kernel@...r.kernel.org
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Paul Mundt <lethal@...ux-sh.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gelixner <tglx@...uxtronix.de>
Subject: [PATCH 2/2] ftrace: Only update $offset when we update $ref_func

The value of $offset should be the offset of $ref_func from the
beginning of the object file. Therefore, we should set both variables
together.

This fixes a bug I was hitting on sh where $offset (which is used to
calcualte the addends for the __mcount_loc entries) was being set
multiple times and didn't correspond to $ref_func's offset in the object
file. The addends in __mcount_loc were calculated incorrectly, resulting
in ftrace dynamically modifying addresses that weren't mcount call
sites.

Signed-off-by: Matt Fleming <matt@...sole-pimps.org>
---
 scripts/recordmcount.pl |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 16c5563..d29baa2 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -403,7 +403,6 @@ while (<IN>) {
     # section found, now is this a start of a function?
     } elsif ($read_function && /$function_regex/) {
 	$text_found = 1;
-	$offset = hex $1;
 	$text = $2;
 
 	# if this is either a local function or a weak function
@@ -412,10 +411,12 @@ while (<IN>) {
 	if (!defined($locals{$text}) && !defined($weak{$text})) {
 	    $ref_func = $text;
 	    $read_function = 0;
+	    $offset = hex $1;
 	} else {
 	    # if we already have a function, and this is weak, skip it
 	    if (!defined($ref_func) && !defined($weak{$text})) {
 		$ref_func = $text;
+		$offset = hex $1;
 	    }
 	}
     } elsif ($read_headers && /$mcount_section/) {
-- 
1.6.4.rc0

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