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authorWill Deacon <will@kernel.org>2020-06-30 14:02:48 +0100
committerWill Deacon <will@kernel.org>2020-11-09 21:49:34 +0000
commite35123d83ee35c31f64ecfbdfabbe5142d3025b8 (patch)
tree42cd6bf50f912bbeb4ba2cf8bbe32d98d89ba2c5 /arch/arm64/kernel/vdso/Makefile
parent5af76fb4228701bd5377880b09b0216a5fd800ef (diff)
arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y
When building with LTO, there is an increased risk of the compiler converting an address dependency headed by a READ_ONCE() invocation into a control dependency and consequently allowing for harmful reordering by the CPU. Ensure that such transformations are harmless by overriding the generic READ_ONCE() definition with one that provides acquire semantics when building with LTO. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/vdso/Makefile')
-rw-r--r--arch/arm64/kernel/vdso/Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index d65f52264aba..a8f8e409e2bf 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -28,7 +28,7 @@ ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
$(btildflags-y) -T
ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
-ccflags-y += -DDISABLE_BRANCH_PROFILING
+ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS)
KASAN_SANITIZE := n