From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v6 1/2] arm64: Define Documentation/arm64/tagged-address-abi.rst Date: Fri, 2 Aug 2019 11:08:35 +0100 Message-ID: <20190802100835.GA4175@arrakis.emea.arm.com> References: <20190725135044.24381-1-vincenzo.frascino@arm.com> <20190725135044.24381-2-vincenzo.frascino@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Dave Hansen Cc: Vincenzo Frascino , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Andrey Konovalov , Szabolcs Nagy List-Id: linux-arch.vger.kernel.org Hi Dave, On Wed, Jul 31, 2019 at 09:43:46AM -0700, Dave Hansen wrote: > On 7/25/19 6:50 AM, Vincenzo Frascino wrote: > > With the relaxed ABI proposed through this document, it is now possible > > to pass tagged pointers to the syscalls, when these pointers are in > > memory ranges obtained by an anonymous (MAP_ANONYMOUS) mmap(). > > I don't see a lot of description of why this restriction is necessary. > What's the problem with supporting MAP_SHARED? We could support MAP_SHARED | MAP_ANONYMOUS (and based on some internal discussions, this would be fine with the hardware memory tagging as well). What we don't want in the ABI is to support file mmap() for top-byte-ignore (or MTE). If you see a use-case, please let us know. -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:48772 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728855AbfHBKIj (ORCPT ); Fri, 2 Aug 2019 06:08:39 -0400 Date: Fri, 2 Aug 2019 11:08:35 +0100 From: Catalin Marinas Subject: Re: [PATCH v6 1/2] arm64: Define Documentation/arm64/tagged-address-abi.rst Message-ID: <20190802100835.GA4175@arrakis.emea.arm.com> References: <20190725135044.24381-1-vincenzo.frascino@arm.com> <20190725135044.24381-2-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dave Hansen Cc: Vincenzo Frascino , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Andrey Konovalov , Szabolcs Nagy Message-ID: <20190802100835.tp62cXAfpIC0_xVof2agSrd-YE_7nNeBg7KS4llm7UA@z> Hi Dave, On Wed, Jul 31, 2019 at 09:43:46AM -0700, Dave Hansen wrote: > On 7/25/19 6:50 AM, Vincenzo Frascino wrote: > > With the relaxed ABI proposed through this document, it is now possible > > to pass tagged pointers to the syscalls, when these pointers are in > > memory ranges obtained by an anonymous (MAP_ANONYMOUS) mmap(). > > I don't see a lot of description of why this restriction is necessary. > What's the problem with supporting MAP_SHARED? We could support MAP_SHARED | MAP_ANONYMOUS (and based on some internal discussions, this would be fine with the hardware memory tagging as well). What we don't want in the ABI is to support file mmap() for top-byte-ignore (or MTE). If you see a use-case, please let us know. -- Catalin