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=-8.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 71285C433E0 for ; Wed, 27 May 2020 18:57:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 11FB42078C for ; Wed, 27 May 2020 18:57:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oOKshksV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 11FB42078C Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 66CF58001A; Wed, 27 May 2020 14:57:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 642B080010; Wed, 27 May 2020 14:57:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 57F5C8001A; Wed, 27 May 2020 14:57:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0114.hostedemail.com [216.40.44.114]) by kanga.kvack.org (Postfix) with ESMTP id 4172480010 for ; Wed, 27 May 2020 14:57:52 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 020E822B319 for ; Wed, 27 May 2020 18:57:52 +0000 (UTC) X-FDA: 76863408384.10.crown82_43012b726d54 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin10.hostedemail.com (Postfix) with ESMTP id D354F8477E for ; Wed, 27 May 2020 18:57:51 +0000 (UTC) X-HE-Tag: crown82_43012b726d54 X-Filterd-Recvd-Size: 3716 Received: from mail-vk1-f195.google.com (mail-vk1-f195.google.com [209.85.221.195]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Wed, 27 May 2020 18:57:51 +0000 (UTC) Received: by mail-vk1-f195.google.com with SMTP id r11so6133753vkf.11 for ; Wed, 27 May 2020 11:57:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Fpy63c23dOxhykDpgNkYc0e/jj9ydzntDTyR3TzEzwU=; b=oOKshksVyBGLuBuCUd+quyrBbn2DnFXm50ek2FV+nnWC10Vc2Z+I/gtnZ3IypCD4Fx gXxBIP/wzAOJJn3wMPNcaKdJWfUFEnNJ5iy4/634yFP9C3y53gykgiFGJMLnkrv4pa82 VbuMfy2wCmwUgkNUPBxU6zhgaM/LAqgX8x8OcC5SVPHdLp9OCdamyiEYDplt+F6T7rNt CZTpMTKKshLKGQva+1GCcfaQ41m4P/vZatfw8XQwBH6PLECjyYmMfm+6otaRyYZlkoJf +2He5a/1crn1NqJGKgI1w+i51L81dUzCLvEqmjYDk4ee1jckJiZXgZst1qGmRZZ/x/cZ mzTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Fpy63c23dOxhykDpgNkYc0e/jj9ydzntDTyR3TzEzwU=; b=LNF0PQLSUMhMWC0Jv9N7Ry/9vOZMKEU5aZK5z1Q0VPceroiQHWOiJbg8OXeXhzbSoh AOYxX47r0x1AgU5I57cGO9FD9ByBj2vcfYj6hKXal+waYgHlgLsRwIXDpdly+ploPZuf vuIwK/drdr7bI26d+kamjGcord67QKxJUXCcrmFy/9gfqhUGEIfIX5lY1QJ/xEZskrzE noYpTzMsN+88kek0wCxvTATwLsow9ULBhy+ffg154hpwAbofQWRiK3S111oeeLoZrvp/ bTKs12QE4+bDV3gKTBtl1mYVdWEQMM6sTTw5EqlykiPJtmaDWDaoQCbmS+iycgni9ZlG naLg== X-Gm-Message-State: AOAM533S+ih3tNtHCkrK3lQpIL5YUTaljQ7qgTqhJU0JxEQIb9j0KYpZ DhwcrYrwqAkSFU/xnFlFpJMAbkxVMbb5gQpfpOfohQ== X-Google-Smtp-Source: ABdhPJy5pnTtE6wlYRg72H36Ak9B9JFNQGA1lIglUkxy0n+VMKw19LyxtiwzE6wUtHu+jW7Au2sEYmLPPI/5udXhrcU= X-Received: by 2002:a1f:bf0e:: with SMTP id p14mr6001114vkf.15.1590605870320; Wed, 27 May 2020 11:57:50 -0700 (PDT) MIME-Version: 1.0 References: <20200515171612.1020-1-catalin.marinas@arm.com> <20200515171612.1020-12-catalin.marinas@arm.com> In-Reply-To: <20200515171612.1020-12-catalin.marinas@arm.com> From: Peter Collingbourne Date: Wed, 27 May 2020 11:57:39 -0700 Message-ID: Subject: Re: [PATCH v4 11/26] arm64: mte: Add PROT_MTE support to mmap() and mprotect() To: Catalin Marinas Cc: Linux ARM , linux-mm@kvack.org, linux-arch@vger.kernel.org, Will Deacon , Dave P Martin , Vincenzo Frascino , Szabolcs Nagy , Kevin Brodsky , Andrey Konovalov , Evgenii Stepanov Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: D354F8477E X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 15, 2020 at 10:16 AM Catalin Marinas wrote: > > To enable tagging on a memory range, the user must explicitly opt in via > a new PROT_MTE flag passed to mmap() or mprotect(). Since this is a new > memory type in the AttrIndx field of a pte, simplify the or'ing of these > bits over the protection_map[] attributes by making MT_NORMAL index 0. Should the userspace stack always be mapped as if with PROT_MTE if the hardware supports it? Such a change would be invisible to non-MTE aware userspace since it would already need to opt in to tag checking via prctl. This would let userspace avoid a complex stack initialization sequence when running with stack tagging enabled on the main thread. Peter