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 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 9C915C54EEB for ; Mon, 23 Mar 2020 15:05:15 +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 6DAF420663 for ; Mon, 23 Mar 2020 15:05:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RkrIsnLJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6DAF420663 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=azUXzqLOzJdegFmnUhquOPTZ5r5yp8MTZBOIqWWzMCg=; b=RkrIsnLJ/tcCpp nxiF1h+bnsVwZHoJ1/21VSCP4x5QwjMLS7uUxg+3mRYrvmSkYNjp8TLlYERdvxnwVBj5upZy1QGkL E+KYrdPaRqU0IpJFUBDOXlkFIUQiYSZY6O8NyPmlohYYDSZvtrkjKAR5uXX3CihqPLGbM87wHMqBO FBkQbAJzwje7U4nHxMlW7qRycj/mL01Y0F86N+ZYlGhRVEexIepv1ZSnqhXE0jkjjUImsqd9+KyM1 J3WAPrm4fiIP1LU/LdcIRwKVHFuUq0IarOlhA1yp9olyiw3kOcR04VWyWdozeTX7yjKGhxBn76GBh y7ZKZqCNGAGdKcJDDWDA==; 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 1jGOdf-0004AA-0j; Mon, 23 Mar 2020 15:05:15 +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 1jGOam-0002TZ-TV for linux-arm-kernel@lists.infradead.org; Mon, 23 Mar 2020 15:02:18 +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 35DAA1FB; Mon, 23 Mar 2020 08:02:16 -0700 (PDT) Received: from C02TD0UTHF1T.local (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 460B13F7C3; Mon, 23 Mar 2020 08:02:12 -0700 (PDT) Date: Mon, 23 Mar 2020 15:02:09 +0000 From: Mark Rutland To: Catalin Marinas Subject: Re: [PATCH v10 00/13] arm64: Branch Target Identification support Message-ID: <20200323150209.GC3959@C02TD0UTHF1T.local> References: <20200316165055.31179-1-broonie@kernel.org> <20200320173945.GC27072@arm.com> <20200323122143.GB4892@mbp> <20200323132412.GD4948@sirena.org.uk> <20200323135722.GA3959@C02TD0UTHF1T.local> <20200323143954.GC4892@mbp> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200323143954.GC4892@mbp> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200323_080217_037662_E0F18117 X-CRM114-Status: GOOD ( 15.13 ) 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: Paul Elliott , Szabolcs Nagy , Andrew Jones , Amit Kachhap , Vincenzo Frascino , Will Deacon , linux-arch@vger.kernel.org, Marc Zyngier , Eugene Syromiatnikov , Peter Zijlstra , "H . J . Lu " , Yu-cheng Yu , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , Kristina =?utf-8?Q?Mart=C5=A1enko?= , Mark Brown , Alexander Viro , Thomas Gleixner , nd@arm.com, linux-arm-kernel@lists.infradead.org, Florian Weimer , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Sudakshina Das 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 Mon, Mar 23, 2020 at 02:39:55PM +0000, Catalin Marinas wrote: > On Mon, Mar 23, 2020 at 01:57:22PM +0000, Mark Rutland wrote: > > On Mon, Mar 23, 2020 at 01:24:12PM +0000, Mark Brown wrote: > > > On Mon, Mar 23, 2020 at 12:21:44PM +0000, Catalin Marinas wrote: > > > > On Fri, Mar 20, 2020 at 05:39:46PM +0000, Szabolcs Nagy wrote: > > > > > > > +int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state, > > > > + bool has_interp, bool is_interp) > > > > +{ > > > > + if (is_interp != has_interp) > > > > + return prot; > > > > + > > > > + if (!(state->flags & ARM64_ELF_BTI)) > > > > + return prot; > > > > + > > > > + if (prot & PROT_EXEC) > > > > + prot |= PROT_BTI; > > > > + > > > > + return prot; > > > > +} > > I think it would be best to document the current behaviour, as it's a > > simple ABI that we can guarantee, and the dynamic linker will have to be > > aware of BTI in order to do the right thing anyhow. > > That's a valid point. If we have an old dynamic linker and the kernel > enabled BTI automatically for the main executable, could things go wrong > (e.g. does the PLT need to be BTI-aware)? Also worth noting that an old dynamic linker won't have ARM64_ELF_BTI set, so the kernel will not enable BTI for this. Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel