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| author | Kevin Brodsky <kevin.brodsky@arm.com> | 2016-05-12 19:39:15 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-11 19:10:11 +0300 |
| commit | a66649dab35033bd67988670fa60c268b0444cda (patch) | |
| tree | 7fc2a35a8054e5e78c1be1a5bdb7f9d1f8ef68ba /arch/arm64/kernel/Makefile | |
| parent | 7d9a7086319daf826ebf06c1abe31728823e1240 (diff) | |
| download | linux-a66649dab35033bd67988670fa60c268b0444cda.tar.xz | |
arm64: fix vdso-offsets.h dependency
arm64/kernel/{vdso,signal}.c include vdso-offsets.h, as well as any
file that includes asm/vdso.h. Therefore, vdso-offsets.h must be
generated before these files are compiled.
The current rules in arm64/kernel/Makefile do not actually enforce
this, because even though $(obj)/vdso is listed as a prerequisite for
vdso-offsets.h, this does not result in the intended effect of
building the vdso subdirectory (before all the other objects). As a
consequence, depending on the order in which the rules are followed,
vdso-offsets.h is updated or not before arm64/kernel/{vdso,signal}.o
are built. The current rules also impose an unnecessary dependency on
vdso-offsets.h for all arm64/kernel/*.o, resulting in unnecessary
rebuilds. This is made obvious when using make -j:
touch arch/arm64/kernel/vdso/gettimeofday.S && make -j$NCPUS arch/arm64/kernel
will sometimes result in none of arm64/kernel/*.o being
rebuilt, sometimes all of them, or even just some of them.
It is quite difficult to ensure that a header is generated before it
is used with recursive Makefiles by using normal rules. Instead,
arch-specific generated headers are normally built in the archprepare
recipe in the arch Makefile (see for instance arch/ia64/Makefile).
Unfortunately, asm-offsets.h is included in gettimeofday.S, and must
therefore be generated before vdso-offsets.h, which is not the case if
archprepare is used. For this reason, a rule run after archprepare has
to be used.
This commit adds rules in arm64/Makefile to build vdso-offsets.h
during the prepare step, ensuring that vdso-offsets.h is generated
before building anything. It also removes the now-unnecessary
dependencies on vdso-offsets.h in arm64/kernel/Makefile. Finally, it
removes the duplication of asm-offsets.h between arm64/kernel/vdso/
and include/generated/ and makes include/generated/vdso-offsets.h a
target in arm64/kernel/vdso/Makefile.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Michal Marek <mmarek@suse.com>
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/Makefile')
| -rw-r--r-- | arch/arm64/kernel/Makefile | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 7700c0c23962..9ef8ec681e30 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -53,7 +53,3 @@ obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) head-y := head.o extra-y += $(head-y) vmlinux.lds - -# vDSO - this must be built first to generate the symbol offsets -$(call objectify,$(arm64-obj-y)): $(obj)/vdso/vdso-offsets.h -$(obj)/vdso/vdso-offsets.h: $(obj)/vdso |