1 Commits

Author	SHA1	Message	Date
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