arm64: vdso: Force the vDSO to be linked as BTI when built for BTI

When the kernel and hence vDSO are built with BTI enabled force the linker
to link the vDSO as BTI. This will cause the linker to warn if any of the
input files do not have the BTI annotation, ensuring that we don't silently
fail to provide a vDSO that is built and annotated for BTI when the
kernel is being built with BTI.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200506195138.22086-11-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index dd2514bb1511fe4fa72271bb9af38564c4fe5607..51ad1cce813354eb7df99feabbfe9180a920b914 100644 (file)
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -17,8 +17,10 @@ obj-vdso := vgettimeofday.o note.o sigreturn.o
 targets := $(obj-vdso) vdso.so vdso.so.dbg
 obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 
+btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti
+
 ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \
-               --build-id -n -T
+               --build-id -n $(btildflags-y) -T
 
 ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18
 ccflags-y += -DDISABLE_BRANCH_PROFILING