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

[Jerome Marchand]

On 10/12/2021 11:58, Heiko Carstens wrote:
> On Fri, Dec 10, 2021 at 10:57:00AM +0100, Miroslav Benes wrote:
> > On Fri, 10 Dec 2021, Jerome Marchand wrote:
> >
> > > 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@xxxxxxxxxx>
> >
> > Yes, we ran into exactly this issue too...
> >
> > > ---
> > >   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]+ <([^\+]*)>\$";
> > >   	$mcount_adjust = 0;
> > >       }
> > >       $alignment = 8;
> >
> > ...and we have exactly the same fix in SLES. I haven't got to submit it
> > to upstream yet :(, many thanks for doing it.
> >
> > So at least
> >
> > Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
>
> Just out of curiosity: am I right if I assume that both of you have
> kernel sources without upstream commit
> d983c89cc96a ("s390/ftrace: Add -mfentry and -mnop-mcount support")
> and the commits directly preceding that one?

That is correct. As a matter of fact, the first thing I did to fix the 
issue was to backport it, but that didn't work since it requires gcc 9 
and that particular kernel is build with gcc 8.5.

Jerome

> Otherwise I would be surprised that this would make any difference.
>
> Applied to s390 tree + added a stable tag.
>
> Thank you!