+ Masahiro, linux-kbuild (EOM)

On Mon, Jul 19, 2021 at 12:07 PM H. Nikolaus Schaller [off-list ref] wrote:

Any chance that it gets merged?

quoted

Am 08.07.2021 um 10:57 schrieb H. Nikolaus Schaller [off-list ref]:

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@letux:~# echo foo | egrep '^(|foo)$'
foo
root@letux:~# echo fool | egrep '^(foo)?$'
root@letux:~# echo fun | egrep '^(|foo)$'
root@letux:~# echo f | egrep '^(|foo)$'
root@letux:~# echo | egrep '^(|foo)$'

root@letux:~# echo foo | egrep '^(foo)?$'
foo
root@letux:~# echo fool | egrep '^(foo)?$'
root@letux:~# echo fun | egrep '^(foo)?$'
root@letux:~# echo f | egrep '^(foo)?$'
root@letux:~# echo | egrep '^(foo)?$'

root@letux:~#

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