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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 6D7A0CA9EAF for ; Thu, 24 Oct 2019 14:39:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3904C20679 for ; Thu, 24 Oct 2019 14:39:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="Wsq8rdKb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502786AbfJXOjH (ORCPT ); Thu, 24 Oct 2019 10:39:07 -0400 Received: from conssluserg-06.nifty.com ([210.131.2.91]:33840 "EHLO conssluserg-06.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732293AbfJXOjH (ORCPT ); Thu, 24 Oct 2019 10:39:07 -0400 Received: from mail-vs1-f46.google.com (mail-vs1-f46.google.com [209.85.217.46]) (authenticated) by conssluserg-06.nifty.com with ESMTP id x9OEcivT007337 for ; Thu, 24 Oct 2019 23:38:45 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-06.nifty.com x9OEcivT007337 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1571927925; bh=5VDOJqWr1P/8RpUKJUiUUgzqRYMuViQTbISV22/DfcM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Wsq8rdKbjufD8xDQo9TYn/vVPfLqU8CWHsul4oOcXL2+aXPYpencUJWWwSK3e35D2 r1rM9S/WmrTYaz2BZmvK3Q++Ya6W+X/E7doaUDPGpJqtcrfyTmXmvYas9LC6dtz7c6 +Wp7bga0LwmkjxC7bnK3lfeIWZErlsOVJtEDo2V3S2VPEdRk6duBPk4lRsrsWbDSL/ STw5curdVNiU7mM8M4A4aCs4z+NHeoPxk0Ve0g/XI+teLFDGPSgtiQYnJpzl/UW1DT /q3CPziyC8B8u7V6ef2AEzLzPC2Ud+TpShsgQS4VnFZCerdl+NYBUp2z94XzY4M3Fp 7AXuq/dNyMwFA== X-Nifty-SrcIP: [209.85.217.46] Received: by mail-vs1-f46.google.com with SMTP id q21so934695vsg.3 for ; Thu, 24 Oct 2019 07:38:45 -0700 (PDT) X-Gm-Message-State: APjAAAXWjnnYAfrRem5ZiGuhB4sFJKorKK5BEE1p2VYSXr5xrN75GMGH 616MgmXexlvfYDTxngO4MvVKGJo0jFM/C3pJN34= X-Google-Smtp-Source: APXvYqzTx9f4+sdDvCmM/G0tcS16/98SXXq+GzkLjkICnXwW7kaMiC+gdVtM0Mg1KgO8XJEVHwsWres9Ec0jaj70OCs= X-Received: by 2002:a67:e290:: with SMTP id g16mr6201871vsf.54.1571927924100; Thu, 24 Oct 2019 07:38:44 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-7-samitolvanen@google.com> <20191022162826.GC699@lakrids.cambridge.arm.com> <20191024132832.GG4300@lakrids.cambridge.arm.com> In-Reply-To: <20191024132832.GG4300@lakrids.cambridge.arm.com> From: Masahiro Yamada Date: Thu, 24 Oct 2019 23:38:07 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS) To: Mark Rutland Cc: Sami Tolvanen , Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel , Dave Martin , Kees Cook , Laura Abbott , Nick Desaulniers , clang-built-linux , Kernel Hardening , linux-arm-kernel , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 24, 2019 at 10:28 PM Mark Rutland wrote: > > On Tue, Oct 22, 2019 at 12:26:02PM -0700, Sami Tolvanen wrote: > > On Tue, Oct 22, 2019 at 9:28 AM Mark Rutland wrote: > > > > > +config SHADOW_CALL_STACK > > > > + bool "Clang Shadow Call Stack" > > > > + depends on ARCH_SUPPORTS_SHADOW_CALL_STACK > > > > + depends on CC_IS_CLANG && CLANG_VERSION >= 70000 > > > > > > Is there a reason for an explicit version check rather than a > > > CC_HAS_ check? e.g. was this available but broken in prior > > > versions of clang? > > > > No, this feature was added in Clang 7. However, > > -fsanitize=shadow-call-stack might require architecture-specific > > flags, so a simple $(cc-option, -fsanitize=shadow-call-stack) in > > arch/Kconfig is not going to work. I could add something like this to > > arch/arm64/Kconfig though: > > > > select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK > > ... > > config CC_HAVE_SHADOW_CALL_STACK > > def_bool $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18) > > > > And then drop CC_IS_CLANG and version check entirely. Thoughts? > > That sounds good to me, yes! > > Thanks, > Mark. If you use cc-option, please add a comment like # supported by Clang 7 or later. I do not know the minimal supported clang version. When we bump the minimal version to clang 7, we can drop the cc-option test entirely. -- Best Regards Masahiro Yamada 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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 1802FCA9EBC for ; Thu, 24 Oct 2019 14:39:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D30B820679 for ; Thu, 24 Oct 2019 14:39:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Q2tDf+2W"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="Wsq8rdKb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D30B820679 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=socionext.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=QWczsW/mWivtKSRpMHm0HatKpbbDHKib/zGvD6WcvZI=; 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a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1571927925; bh=5VDOJqWr1P/8RpUKJUiUUgzqRYMuViQTbISV22/DfcM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Wsq8rdKbjufD8xDQo9TYn/vVPfLqU8CWHsul4oOcXL2+aXPYpencUJWWwSK3e35D2 r1rM9S/WmrTYaz2BZmvK3Q++Ya6W+X/E7doaUDPGpJqtcrfyTmXmvYas9LC6dtz7c6 +Wp7bga0LwmkjxC7bnK3lfeIWZErlsOVJtEDo2V3S2VPEdRk6duBPk4lRsrsWbDSL/ STw5curdVNiU7mM8M4A4aCs4z+NHeoPxk0Ve0g/XI+teLFDGPSgtiQYnJpzl/UW1DT /q3CPziyC8B8u7V6ef2AEzLzPC2Ud+TpShsgQS4VnFZCerdl+NYBUp2z94XzY4M3Fp 7AXuq/dNyMwFA== X-Nifty-SrcIP: [209.85.217.47] Received: by mail-vs1-f47.google.com with SMTP id y129so16348679vsc.6 for ; Thu, 24 Oct 2019 07:38:45 -0700 (PDT) X-Gm-Message-State: APjAAAU1XN1MEcqaOPQqiRHxRcMNThP6lbjQWQ2IhAdP8gKOjsaUyQs9 2AJE3oDhGuwdOfzkFKXtO3yXhj4nAkgst5uW6rY= X-Google-Smtp-Source: APXvYqzTx9f4+sdDvCmM/G0tcS16/98SXXq+GzkLjkICnXwW7kaMiC+gdVtM0Mg1KgO8XJEVHwsWres9Ec0jaj70OCs= X-Received: by 2002:a67:e290:: with SMTP id g16mr6201871vsf.54.1571927924100; Thu, 24 Oct 2019 07:38:44 -0700 (PDT) MIME-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191018161033.261971-7-samitolvanen@google.com> <20191022162826.GC699@lakrids.cambridge.arm.com> <20191024132832.GG4300@lakrids.cambridge.arm.com> In-Reply-To: <20191024132832.GG4300@lakrids.cambridge.arm.com> From: Masahiro Yamada Date: Thu, 24 Oct 2019 23:38:07 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS) To: Mark Rutland X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191024_073905_209321_5B5B0C10 X-CRM114-Status: GOOD ( 16.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , Ard Biesheuvel , Catalin Marinas , Kernel Hardening , Nick Desaulniers , LKML , Steven Rostedt , clang-built-linux , Sami Tolvanen , Laura Abbott , Will Deacon , Dave Martin , linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Oct 24, 2019 at 10:28 PM Mark Rutland wrote: > > On Tue, Oct 22, 2019 at 12:26:02PM -0700, Sami Tolvanen wrote: > > On Tue, Oct 22, 2019 at 9:28 AM Mark Rutland wrote: > > > > > +config SHADOW_CALL_STACK > > > > + bool "Clang Shadow Call Stack" > > > > + depends on ARCH_SUPPORTS_SHADOW_CALL_STACK > > > > + depends on CC_IS_CLANG && CLANG_VERSION >= 70000 > > > > > > Is there a reason for an explicit version check rather than a > > > CC_HAS_ check? e.g. was this available but broken in prior > > > versions of clang? > > > > No, this feature was added in Clang 7. However, > > -fsanitize=shadow-call-stack might require architecture-specific > > flags, so a simple $(cc-option, -fsanitize=shadow-call-stack) in > > arch/Kconfig is not going to work. I could add something like this to > > arch/arm64/Kconfig though: > > > > select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK > > ... > > config CC_HAVE_SHADOW_CALL_STACK > > def_bool $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18) > > > > And then drop CC_IS_CLANG and version check entirely. Thoughts? > > That sounds good to me, yes! > > Thanks, > Mark. If you use cc-option, please add a comment like # supported by Clang 7 or later. I do not know the minimal supported clang version. When we bump the minimal version to clang 7, we can drop the cc-option test entirely. -- Best Regards Masahiro Yamada _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel