linux-kernel - Re: [PATCH] recordmcount.pl: look for jgnop instruction as well as bcrl on s390

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Date:   Thu, 23 Dec 2021 18:40:18 +0100
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     Jerome Marchand <jmarchan@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] recordmcount.pl: look for jgnop instruction as well as
 bcrl on s390

> > On s390, recordmcount.pl is looking for "bcrl 0,<xxx>" instructions in
> > the objdump -d outpout. However since binutils 2.37, objdump -d
> > display "jgnop <xxx>" for the same instruction. Update the
> > mcount_regex so that it accepts both.
> > 
> > Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
> > ---
> >  scripts/recordmcount.pl | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> > index 7d631aaa0ae1..52a000b057a5 100755
> > --- a/scripts/recordmcount.pl
> > +++ b/scripts/recordmcount.pl
> > @@ -219,7 +219,7 @@ if ($arch eq "x86_64") {
> >  
> >  } elsif ($arch eq "s390" && $bits == 64) {
> >      if ($cc =~ /-DCC_USING_HOTPATCH/) {
> > -	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*brcl\\s*0,[0-9a-f]+ <([^\+]*)>\$";
> > +	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*(bcrl\\s*0,|jgnop\\s*)[0-9a-f]+ <([^\+]*)>\$";
> 
> there is a typo I did not notice before. Sorry about that *sigh*.
> 
> s/bcrl/brcl/ on the whole patch.

Hm.. nice. So I will schedule the patch below for next week. Actually
tested with the variants I mentioned in the commit message.

>From 30b3302ae3e9fb30c4cef5c17a2a63ba6ba34195 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@...ux.ibm.com>
Date: Thu, 23 Dec 2021 17:43:14 +0100
Subject: [PATCH] recordmcount.pl: fix typo in s390 mcount regex

Commit 85bf17b28f97 ("recordmcount.pl: look for jgnop instruction as well
as bcrl on s390") added a new alternative mnemonic for the existing brcl
instruction. This is required for the combination old gcc version (pre 9.0)
and binutils since version 2.37.
However at the same time this commit introduced a typo, replacing brcl with
bcrl. As a result no mcount locations are detected anymore with old gcc
versions (pre 9.0) and binutils before version 2.37.
Fix this by using the correct mnemonic again.

Reported-by: Miroslav Benes <mbenes@...e.cz>
Cc: Jerome Marchand <jmarchan@...hat.com>
Cc: <stable@...r.kernel.org>
Fixes: 85bf17b28f97 ("recordmcount.pl: look for jgnop instruction as well as bcrl on s390")
Link: https://lore.kernel.org/r/alpine.LSU.2.21.2112230949520.19849@pobox.suse.cz
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
 scripts/recordmcount.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 52a000b057a5..3ccb2c70add4 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -219,7 +219,7 @@ if ($arch eq "x86_64") {
 
 } elsif ($arch eq "s390" && $bits == 64) {
     if ($cc =~ /-DCC_USING_HOTPATCH/) {
-	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*(bcrl\\s*0,|jgnop\\s*)[0-9a-f]+ <([^\+]*)>\$";
+	$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*(brcl\\s*0,|jgnop\\s*)[0-9a-f]+ <([^\+]*)>\$";
 	$mcount_adjust = 0;
     }
     $alignment = 8;
-- 
2.32.0