linux/arch
Masahiro Yamada bce74491c3 powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o
vgettimeofday.o is unnecessarily rebuilt. Adding it to 'targets' is not
enough to fix the issue. Kbuild is correctly rebuilding it because the
command line is changed.

PowerPC builds each vdso directory twice; first in vdso_prepare to
generate vdso{32,64}-offsets.h, second as part of the ordinary build
process to embed vdso{32,64}.so.dbg into the kernel.

The problem shows up when CONFIG_PPC_WERROR=y due to the following line
in arch/powerpc/Kbuild:

  subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror

In the preparation stage, Kbuild directly visits the vdso directories,
hence it does not inherit subdir-ccflags-y. In the second descend,
Kbuild adds -Werror, which results in the command line flipping
with/without -Werror.

It implies a potential danger; if a more critical flag that would impact
the resulted vdso, the offsets recorded in the headers might be different
from real offsets in the embedded vdso images.

Removing the unneeded second descend solves the problem.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/linuxppc-dev/87tuslxhry.fsf@mpe.ellerman.id.au/
Link: https://lore.kernel.org/r/20201223171142.707053-1-masahiroy@kernel.org
2021-01-30 22:23:42 +11:00
..
alpha local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
arc local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
arm local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
arm64 local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
c6x tif-task_work.arch-2020-12-14 2020-12-16 12:33:35 -08:00
csky local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
h8300 local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
hexagon local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
ia64 local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
m68k local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
microblaze local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
mips local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
nds32 local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
nios2 tif-task_work.arch-2020-12-14 2020-12-16 12:33:35 -08:00
openrisc local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
parisc local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
powerpc powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o 2021-01-30 22:23:42 +11:00
riscv local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
s390 - Update defconfigs and sort config select list. 2021-01-02 12:22:46 -08:00
sh local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
sparc local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
um This pull request contains the following changes for UML: 2020-12-17 17:56:44 -08:00
x86 local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
xtensa local64.h: make <asm/local64.h> mandatory 2020-12-29 15:36:49 -08:00
.gitignore
Kconfig kasan: allow VMAP_STACK for HW_TAGS mode 2020-12-22 12:55:08 -08:00