From 4f166564014aba65ad6f15b612f6711fd0f117ee Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 2 Oct 2018 21:26:50 -0700 Subject: x86/vdso: Only enable vDSO retpolines when enabled and supported When I fixed the vDSO build to use inline retpolines, I messed up the Makefile logic and made it unconditional. It should have depended on CONFIG_RETPOLINE and on the availability of compiler support. This broke the build on some older compilers. Reported-by: nikola.ciprich@linuxbox.cz Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: David Woodhouse Cc: Linus Torvalds Cc: Matt Rickard Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: jason.vas.dias@gmail.com Cc: stable@vger.kernel.org Fixes: 2e549b2ee0e3 ("x86/vdso: Fix vDSO build if a retpoline is emitted") Link: http://lkml.kernel.org/r/08a1f29f2c238dd1f493945e702a521f8a5aa3ae.1538540801.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/vdso/Makefile | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index fa3f439f0a92..141d415a8c80 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -68,7 +68,13 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \ $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \ -fno-omit-frame-pointer -foptimize-sibling-calls \ - -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO $(RETPOLINE_VDSO_CFLAGS) + -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO + +ifdef CONFIG_RETPOLINE +ifneq ($(RETPOLINE_VDSO_CFLAGS),) + CFL += $(RETPOLINE_VDSO_CFLAGS) +endif +endif $(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) @@ -138,7 +144,13 @@ KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector) KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls) KBUILD_CFLAGS_32 += -fno-omit-frame-pointer KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING -KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS) + +ifdef CONFIG_RETPOLINE +ifneq ($(RETPOLINE_VDSO_CFLAGS),) + KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS) +endif +endif + $(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32) $(obj)/vdso32.so.dbg: FORCE \ -- cgit v1.2.3-59-g8ed1b