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

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Message-Id: <4AC1CCE9-CCAF-4D4B-BAD5-CEB9E5155FDF@goldelico.com>
Date:   Mon, 19 Jul 2021 21:04:53 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     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>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     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
Subject: Re: [PATCH 0/2] Regex fixes for mips and x86 cross-compile

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
>