diff options
| author | Masahiro Yamada <masahiroy@kernel.org> | 2020-12-24 02:11:41 +0900 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-01-30 22:23:42 +1100 |
| commit | bce74491c3008e27dd6e8f79a83b4faa77a08f7e (patch) | |
| tree | 229ccf821426158119548860301812d07d176221 /arch/powerpc/kernel/vdso64/Makefile | |
| parent | 344717a14cd7272f88346022a77742323346299e (diff) | |
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
Diffstat (limited to 'arch/powerpc/kernel/vdso64/Makefile')
| -rw-r--r-- | arch/powerpc/kernel/vdso64/Makefile | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile index bf363ff37152..a06fb9b461fc 100644 --- a/arch/powerpc/kernel/vdso64/Makefile +++ b/arch/powerpc/kernel/vdso64/Makefile @@ -17,7 +17,7 @@ endif # Build rules -targets := $(obj-vdso64) vdso64.so.dbg +targets := $(obj-vdso64) vdso64.so.dbg vgettimeofday.o obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64)) GCOV_PROFILE := n @@ -29,15 +29,11 @@ ccflags-y := -shared -fno-common -fno-builtin -nostdlib \ -Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both asflags-y := -D__VDSO64__ -s -obj-y += vdso64_wrapper.o targets += vdso64.lds CPPFLAGS_vdso64.lds += -P -C -U$(ARCH) $(obj)/vgettimeofday.o: %.o: %.c FORCE -# Force dependency (incbin is bad) -$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so.dbg - # link rule for the .so file, .lds has to be first $(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday.o FORCE $(call if_changed,vdso64ld_and_check) |