From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:45678 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728609AbeICVqO (ORCPT ); Mon, 3 Sep 2018 17:46:14 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Thomas Gleixner , Matt Rickard , Borislav Petkov , Jason Vas Dias , David Woodhouse , Peter Zijlstra , Andi Kleen Subject: [PATCH 4.14 114/165] x86/vdso: Fix vDSO build if a retpoline is emitted Date: Mon, 3 Sep 2018 18:56:40 +0200 Message-Id: <20180903165701.245301231@linuxfoundation.org> In-Reply-To: <20180903165655.003605184@linuxfoundation.org> References: <20180903165655.003605184@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski 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 Signed-off-by: Thomas Gleixner Acked-by: Matt Rickard Cc: Borislav Petkov Cc: Jason Vas Dias Cc: David Woodhouse Cc: Peter Zijlstra Cc: Andi Kleen Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman --- 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 \