From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 177F9C4321D for ; Thu, 16 Aug 2018 19:41:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C5DF421480 for ; Thu, 16 Aug 2018 19:41:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="wYyP4nms" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C5DF421480 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726108AbeHPWlj (ORCPT ); Thu, 16 Aug 2018 18:41:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:38270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbeHPWlj (ORCPT ); Thu, 16 Aug 2018 18:41:39 -0400 Received: from localhost (c-71-202-137-17.hsd1.ca.comcast.net [71.202.137.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5135C20C10; Thu, 16 Aug 2018 19:41:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1534448476; bh=52MJWQI0s4ejBxIPr6daivsgW5lTHd5X1qbivVVNcLE=; h=From:To:Cc:Subject:Date:From; b=wYyP4nmsHhquOkGlztIBrE/9tQTd8qvbSqvorTDFYB8IvJ4L8EO0VUy2LfBZ7FBd4 pJserX+951ajSWnU3cso9DSJnKWVPnLCJhoOG5tYjuvX1x95cTTliJAIeuhg851G/7 zJOeVYzxVJbZ5F0Wz4I8H5oYTQaOUWKWTwJC/nm0= From: Andy Lutomirski To: x86@kernel.org, LKML Cc: Borislav Petkov , Andy Lutomirski , Matt Rickard , Jason Vas Dias , David Woodhouse , Peter Zijlstra , Andi Kleen Subject: [PATCH] x86/vdso: Fix vDSO build if a retpoline is emitted Date: Thu, 16 Aug 2018 12:41:15 -0700 Message-Id: X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: Matt Rickard Cc: Jason Vas Dias Cc: David Woodhouse Cc: Peter Zijlstra Cc: Andi Kleen Fixes: commit 76b043848fd2 ("x86/retpoline: Add initial retpoline support") Signed-off-by: Andy Lutomirski --- This is a bit of a marginal candidate for the merge window. There are a couple of reports of people hitting this while hacking on the vDSO, but I haven't seen any report of anyone hitting this on a stock kernel. Feel free to tell me to buzz of and send it later :) Makefile | 4 ++++ arch/x86/entry/vdso/Makefile | 6 ++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index a0650bf79606..7bab2e90e4e1 100644 --- a/Makefile +++ b/Makefile @@ -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 \ -- 2.17.1