linux-kernel - Re: [PATCH 0/2] Regex fixes for mips and x86 cross-compile

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Date:   Mon, 19 Jul 2021 13:37:36 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Jessica Yu <jeyu@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Emil Velikov <emil.l.velikov@...il.com>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>, "H. Peter Anvin" <hpa@...or.com>,
        linux-mips <linux-mips@...r.kernel.org>,
        linux-kernel@...r.kernel.org, kernel@...a-handheld.com,
        Masahiro Yamada <masahiroy@...nel.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH 0/2] Regex fixes for mips and x86 cross-compile

+ Masahiro, linux-kbuild (EOM)

On Mon, Jul 19, 2021 at 12:07 PM H. Nikolaus Schaller <hns@...delico.com> wrote:
>
> Any chance that it gets merged?
>
> > Am 08.07.2021 um 10:57 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> >
> > Trying to run the x86 relocs tool on a BSD based HOSTCC (cross
> > compilation environment) leads to errors like
> >
> >  VOFFSET arch/x86/boot/compressed/../voffset.h - due to: vmlinux
> >  CC      arch/x86/boot/compressed/misc.o - due to: arch/x86/boot/compressed/../voffset.h
> >  OBJCOPY arch/x86/boot/compressed/vmlinux.bin - due to: vmlinux
> >  RELOCS  arch/x86/boot/compressed/vmlinux.relocs - due to: vmlinux
> > empty (sub)expressionarch/x86/boot/compressed/Makefile:118: recipe for target 'arch/x86/boot/compressed/vmlinux.relocs' failed
> > make[3]: *** [arch/x86/boot/compressed/vmlinux.relocs] Error 1
> >
> > and when cross compiling a MIPS kernel on a BSD based HOSTCC
> > we get errors like
> >
> >  SYNC    include/config/auto.conf.cmd - due to: .config
> > egrep: empty (sub)expression
> >  UPD     include/config/kernel.release
> >  HOSTCC  scripts/dtc/dtc.o - due to target missing
> >
> > It turns out that relocs.c on x86 uses patterns like
> >
> >       "something(|_end)"
> >
> > while MIPS uses egrep with
> >
> >       (|MINOR_|PATCHLEVEL_)
> >
> > In both cases it is not valid syntax or gives undefined results
> > according to POSIX 9.5.3 ERE Grammar
> >
> >       https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html
> >
> > It seems to be silently accepted by the Linux regcmp() or egrep
> > implementation while a BSD host complains.
> >
> > Such patterns can be replaced by a transformation like
> >
> >       "(|p1|p2)" -> "(p1|p2)?"
> >
> > Test Linux:
> >
> > root@...ux:~# echo foo | egrep '^(|foo)$'
> > foo
> > root@...ux:~# echo fool | egrep '^(foo)?$'
> > root@...ux:~# echo fun | egrep '^(|foo)$'
> > root@...ux:~# echo f | egrep '^(|foo)$'
> > root@...ux:~# echo | egrep '^(|foo)$'
> >
> > root@...ux:~# echo foo | egrep '^(foo)?$'
> > foo
> > root@...ux:~# echo fool | egrep '^(foo)?$'
> > root@...ux:~# echo fun | egrep '^(foo)?$'
> > root@...ux:~# echo f | egrep '^(foo)?$'
> > root@...ux:~# echo | egrep '^(foo)?$'
> >
> > root@...ux:~#
> >
> > Test BSD:
> >
> > iMac:master hns$ echo foo | egrep '^(|foo)$'
> > egrep: empty (sub)expression
> > iMac:master hns$ echo fool | egrep '^(foo)?$'
> > egrep: empty (sub)expression
> > iMac:master hns$ echo fun | egrep '^(|foo)$'
> > egrep: empty (sub)expression
> > iMac:master hns$ echo f | egrep '^(|foo)$'
> > egrep: empty (sub)expression
> > iMac:master hns$ echo | egrep '^(|foo)$'
> > egrep: empty (sub)expression
> > iMac:master hns$ echo foo | egrep '^(foo)?$'
> > foo
> > iMac:master hns$ echo fool | egrep '^(foo)?$'
> > iMac:master hns$ echo fun | egrep '^(foo)?$'
> > iMac:master hns$ echo f | egrep '^(foo)?$'
> > iMac:master hns$ echo | egrep '^(foo)?$'
> >
> > iMac:master hns$
> >
> >
> > H. Nikolaus Schaller (2):
> >  x86/tools/relocs: Fix non-POSIX regexp
> >  arch: mips: Fix non-POSIX regexp
> >
> > arch/mips/Makefile      | 2 +-
> > arch/x86/tools/relocs.c | 8 ++++----
> > 2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > --
> > 2.31.1
> >
>


-- 
Thanks,
~Nick Desaulniers