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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 4A21FC47254 for ; Tue, 5 May 2020 16:50:55 +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 1B564207DD for ; Tue, 5 May 2020 16:50:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GdbyRVM7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B564207DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.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:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0AaFybFNkfsyWX8e1RciJlCkOJ0Ojddy07NqrRr/7Sg=; b=GdbyRVM7HikOOg mHGRhpd26RO7UxDOZnia/Y1HxfawvtU2cHX9KGNJpoFMOHtd/2gw8uaxVlTnPDOoN3x1FDAyJP+vV OZ2dOyqS8aPhjkztmOv5Imsf4yVy31sQ6aIvUnj3PSrvhAU1cUIsEDO9erGfFoQ8y/C4VndgFahC+ rsWnAMd6DJRb6OKf0lq5x6Z3IWwIalRwIYJ6Ns8+VRaTdGr6O39/ksEai+AHFqr6GDu6kT9sO1c0Y rsU1paaZlcvQT1b51+2LvqNdOhESS+GM0W33/eX0pJw8qDpbb2dBzzyGSkdTxTaWY47HyX7RwDYkp 0n6Gj+4dk3mA1x0q0L1Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jW0mU-0000Nr-8i; Tue, 05 May 2020 16:50:54 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jW0mR-0000MA-TP for linux-arm-kernel@lists.infradead.org; Tue, 05 May 2020 16:50:53 +0000 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 36EBF31B; Tue, 5 May 2020 09:50:48 -0700 (PDT) Received: from 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 515583F305; Tue, 5 May 2020 09:50:47 -0700 (PDT) Date: Tue, 5 May 2020 17:50:45 +0100 From: Dave Martin To: Mark Brown Subject: Re: [PATCH v2 01/10] arm64: bti: Support building kernel C code using BTI Message-ID: <20200505165045.GQ30377@arm.com> References: <20200429211641.9279-1-broonie@kernel.org> <20200429211641.9279-2-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200429211641.9279-2-broonie@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200505_095052_001145_22AFA71D X-CRM114-Status: GOOD ( 14.55 ) 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: Catalin Marinas , Vincenzo Frascino , Will Deacon , Kees Cook , linux-arm-kernel@lists.infradead.org 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 Wed, Apr 29, 2020 at 10:16:32PM +0100, Mark Brown wrote: > When running with BTI enabled we need to ask the compiler to enable > generation of BTI landing pads beyond those generated as a result of > pointer authentication instructions being landing pads. Since the two > features are practically speaking unlikely to be used separately we > will make kernel mode BTI depend on pointer authentication in order > to simplify the Makefile. > > Signed-off-by: Mark Brown > --- > arch/arm64/Makefile | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile > index 85e4149cc5d5..90150b5b180e 100644 > --- a/arch/arm64/Makefile > +++ b/arch/arm64/Makefile > @@ -71,7 +71,11 @@ branch-prot-flags-y += $(call cc-option,-mbranch-protection=none) > > ifeq ($(CONFIG_ARM64_PTR_AUTH),y) > branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all > +ifeq ($(CONFIG_ARM64_BTI_KERNEL),y) > +branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protection=pac-ret+leaf+bti > +else > branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf > +endif Is it worth a comment to explain how this differs from -mbranch-protection=standard, and why we're not using that here? Cheers ---Dave _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel