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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D7A28C432C3 for ; Fri, 15 Nov 2019 14:44:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A93AA2073A for ; Fri, 15 Nov 2019 14:44:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727729AbfKOOoE (ORCPT ); Fri, 15 Nov 2019 09:44:04 -0500 Received: from foss.arm.com ([217.140.110.172]:60396 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727496AbfKOOoE (ORCPT ); Fri, 15 Nov 2019 09:44:04 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8C4DF31B; Fri, 15 Nov 2019 06:44:03 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4FC513F534; Fri, 15 Nov 2019 06:44:01 -0800 (PST) Date: Fri, 15 Nov 2019 14:43:59 +0000 From: Mark Rutland To: Sami Tolvanen Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 12/14] arm64: vdso: disable Shadow Call Stack Message-ID: <20191115144358.GG41572@lakrids.cambridge.arm.com> References: <20191018161033.261971-1-samitolvanen@google.com> <20191105235608.107702-1-samitolvanen@google.com> <20191105235608.107702-13-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191105235608.107702-13-samitolvanen@google.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 05, 2019 at 03:56:06PM -0800, Sami Tolvanen wrote: > Shadow stacks are only available in the kernel, so disable SCS > instrumentation for the vDSO. > > Signed-off-by: Sami Tolvanen > Reviewed-by: Nick Desaulniers > Reviewed-by: Kees Cook I gave this a spin, looked at objdump, and found everything in the vDSO was a leaf function. I hacked the code around a bit to force a function call, and I see that just uses x29 and x30 as expected, with nothing touching x18. Reviewed-by: Mark Rutland Mark. > --- > arch/arm64/kernel/vdso/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > index dd2514bb1511..a87a4f11724e 100644 > --- a/arch/arm64/kernel/vdso/Makefile > +++ b/arch/arm64/kernel/vdso/Makefile > @@ -25,7 +25,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING > > VDSO_LDFLAGS := -Bsymbolic > > -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os > +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) > KBUILD_CFLAGS += $(DISABLE_LTO) > KASAN_SANITIZE := n > UBSAN_SANITIZE := n > -- > 2.24.0.rc1.363.gb1bccd3e3d-goog >