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

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Date:   Tue, 3 Aug 2021 17:58:22 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
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 Mailing List <linux-kernel@...r.kernel.org>,
        kernel@...a-handheld.com,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH 0/2] Regex fixes for mips and x86 cross-compile

Hi all,
any chance to get that reviewed and merged into v5.15-rc1 and backported to stable?
Thank you,
Nikolaus Schaller


> Am 19.07.2021 um 22:37 schrieb Nick Desaulniers <ndesaulniers@...gle.com>:
> 
> + 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