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| author | Masahiro Yamada <masahiroy@kernel.org> | 2020-12-18 05:45:40 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2021-01-20 15:18:46 +0300 |
| commit | a5b8ca97fbf8300a5e21c393df25ce6f521e7939 (patch) | |
| tree | e408b44b8200420fb5e05c14edacbf566dbb503e /arch/arm64/Makefile | |
| parent | 19c329f6808995b142b3966301f217c831e7cf31 (diff) | |
| download | linux-a5b8ca97fbf8300a5e21c393df25ce6f521e7939.tar.xz | |
arm64: do not descend to vdso directories twice
arm64 descends into each vdso directory twice; first in vdso_prepare,
second during the ordinary build process.
PPC mimicked it and uncovered a problem [1]. In the first descend,
Kbuild directly visits the vdso directories, therefore it does not
inherit subdir-ccflags-y from upper directories.
This means the command line parameters may differ between the two.
If it happens, the offset values in the generated headers might be
different from real offsets of vdso.so in the kernel.
This potential danger should be avoided. The vdso directories are
built in the vdso_prepare stage, so the second descend is unneeded.
[1]: https://lore.kernel.org/linux-kbuild/CAK7LNARAkJ3_-4gX0VA2UkapbOftuzfSTVMBbgbw=HD8n7N+7w@mail.gmail.com/T/#ma10dcb961fda13f36d42d58fa6cb2da988b7e73a
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20201218024540.1102650-1-masahiroy@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/Makefile')
| -rw-r--r-- | arch/arm64/Makefile | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 90309208bb28..5b84aec31ed3 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -188,10 +188,12 @@ ifeq ($(KBUILD_EXTMOD),) # this hack. prepare: vdso_prepare vdso_prepare: prepare0 - $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h - $(if $(CONFIG_COMPAT_VDSO),$(Q)$(MAKE) \ - $(build)=arch/arm64/kernel/vdso32 \ - include/generated/vdso32-offsets.h) + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso \ + include/generated/vdso-offsets.h arch/arm64/kernel/vdso/vdso.so +ifdef CONFIG_COMPAT_VDSO + $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \ + include/generated/vdso32-offsets.h arch/arm64/kernel/vdso32/vdso.so +endif endif define archhelp |