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| author | Andy Lutomirski <luto@kernel.org> | 2018-08-16 12:41:15 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-08-20 18:04:41 +0200 |
| commit | 2e549b2ee0e358bc758480e716b881f9cabedb6a (patch) | |
| tree | 0fda84bdf28d9eda10549cbc8327bd73ab12decf | |
| parent | f19f5c49bbc3ffcc9126cc245fc1b24cc29f4a37 (diff) | |
| download | lwn-2e549b2ee0e358bc758480e716b881f9cabedb6a.tar.gz lwn-2e549b2ee0e358bc758480e716b881f9cabedb6a.zip | |
x86/vdso: Fix vDSO build if a retpoline is emitted
Currently, if the vDSO ends up containing an indirect branch or
call, GCC will emit the "external thunk" style of retpoline, and it
will fail to link.
Fix it by building the vDSO with inline retpoline thunks.
I haven't seen any reports of this triggering on an unpatched
kernel.
Fixes: commit 76b043848fd2 ("x86/retpoline: Add initial retpoline support")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Matt Rickard <matt@softrans.com.au>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Vas Dias <jason.vas.dias@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org
| -rw-r--r-- | Makefile | 4 | ||||
| -rw-r--r-- | arch/x86/entry/vdso/Makefile | 6 |
2 files changed, 8 insertions, 2 deletions
@@ -507,9 +507,13 @@ KBUILD_AFLAGS += $(call cc-option, -no-integrated-as) endif RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register +RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk +RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG))) +RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG))) export RETPOLINE_CFLAGS +export RETPOLINE_VDSO_CFLAGS KBUILD_CFLAGS += $(call cc-option,-fno-PIE) KBUILD_AFLAGS += $(call cc-option,-fno-PIE) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 9f695f517747..fa3f439f0a92 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -68,9 +68,9 @@ $(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 + -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO $(RETPOLINE_VDSO_CFLAGS) -$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) # # vDSO code runs in userspace and -pg doesn't help with profiling anyway. @@ -132,11 +132,13 @@ KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic 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) $(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32) $(obj)/vdso32.so.dbg: FORCE \ |