Messages in this thread |  | | Date | Tue, 2 Oct 2018 10:06:55 +0200 | From | Nikola Ciprich <> | Subject | Re: [PATCH 4.14 114/165] x86/vdso: Fix vDSO build if a retpoline is emitted |
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Hi Greg and others,
sorry for reporting this so late, but still...
this breaks build on older compilers, since it requires -mindirect-branch=thunk-inline -mindirect-branch-register even though retpoline support is disabled in kernel config.. is this expected?
BR
nik
On Mon, Sep 03, 2018 at 06:56:40PM +0200, Greg Kroah-Hartman wrote: > 4.14-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Andy Lutomirski <luto@kernel.org> > > commit 2e549b2ee0e358bc758480e716b881f9cabedb6a upstream. > > 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 > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > --- > Makefile | 4 ++++ > arch/x86/entry/vdso/Makefile | 6 ++++-- > 2 files changed, 8 insertions(+), 2 deletions(-) > > --- a/Makefile > +++ b/Makefile > @@ -490,9 +490,13 @@ KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG > 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 > > ifeq ($(config-targets),1) > # =========================================================================== > --- a/arch/x86/entry/vdso/Makefile > +++ b/arch/x86/entry/vdso/Makefile > @@ -74,9 +74,9 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.d > 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. > @@ -147,11 +147,13 @@ KBUILD_CFLAGS_32 := $(filter-out -mcmode > 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 \ > >
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