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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/vdso32
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/vdso32')
-rw-r--r--arch/arm64/kernel/vdso32/Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index 79280c53b9a6..a1e0f91e6cea 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -48,7 +48,7 @@ cc32-as-instr = $(call try-run,\
# As a result we set our own flags here.
# KBUILD_CPPFLAGS and NOSTDINC_FLAGS from top-level Makefile
-VDSO_CPPFLAGS := -D__KERNEL__ -nostdinc -isystem $(shell $(CC_COMPAT) -print-file-name=include)
+VDSO_CPPFLAGS := -DBUILD_VDSO -D__KERNEL__ -nostdinc -isystem $(shell $(CC_COMPAT) -print-file-name=include)
VDSO_CPPFLAGS += $(LINUXINCLUDE)
# Common C and assembly flags