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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EA6FC761AF for ; Wed, 29 Mar 2023 16:18:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229517AbjC2QSV (ORCPT ); Wed, 29 Mar 2023 12:18:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229586AbjC2QSU (ORCPT ); Wed, 29 Mar 2023 12:18:20 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF3AC5B92 for ; Wed, 29 Mar 2023 09:17:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680106627; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9PZc/wL1SaOvzMH0Hm9CmGIiBNNws8MikE2aRTtEWQ4=; b=UgV6hCF1cOaKlBVeeu/5G14Y0hglfhAnmUUzhARACj3g9qYVYaL43m3jQtSm2sQ8Zcxo7X RdyJEeDtfGc0zp6FUyJ5SUA08BScOzPHftSDiZfybxMyYRiINYsyxee91dwZVO09c+r2p0 sghoNZkzI9xvZgOHa8PbcS6HUMECEe4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-70-m06UBDt5NEeHbLQfow7d0g-1; Wed, 29 Mar 2023 12:03:36 -0400 X-MC-Unique: m06UBDt5NEeHbLQfow7d0g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8EBAE8030D3; Wed, 29 Mar 2023 16:03:35 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.161]) by smtp.corp.redhat.com (Postfix) with SMTP id 82BCEC15BA0; Wed, 29 Mar 2023 16:03:31 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 29 Mar 2023 18:03:27 +0200 (CEST) Date: Wed, 29 Mar 2023 18:03:23 +0200 From: Oleg Nesterov To: Arnd Bergmann Cc: Gregory Price , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linux-Arch , avagin@gmail.com, Peter Zijlstra , Andy Lutomirski , krisman@collabora.com, Thomas Gleixner , Jonathan Corbet , shuah , Catalin Marinas , Will Deacon , Mark Rutland , tongtiangen@huawei.com, Robin Murphy , Gregory Price Subject: Re: [PATCH v14 1/4] asm-generic,arm64: create task variant of access_ok Message-ID: <20230329160322.GA4477@redhat.com> References: <20230328164811.2451-1-gregory.price@memverge.com> <20230328164811.2451-2-gregory.price@memverge.com> <20230329151515.GA913@redhat.com> <9a456346-e207-44e1-873e-40d21334e01b@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9a456346-e207-44e1-873e-40d21334e01b@app.fastmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 03/29, Arnd Bergmann wrote: > > On Wed, Mar 29, 2023, at 17:15, Oleg Nesterov wrote: > > > > This look as if access_ok() or __access_ok() doesn't depend on task, but > > this is not true in general. Say, TASK_SIZE_MAX can check is_32bit_task() > > test_thread_flag(TIF_32BIT...) and this uses "current". > > > > Again, we probably do not care, but I don't like the fact task_access_ok() > > looks as if task_access_ok(task) returns the same result as "task" calling > > access_ok(). > > I think the idea of TASK_SIZE_MAX is that it is a compile-time constant and in fact independent of current, while TASK_SIZE > takes TIF_32BIT into account. Say, arch/loongarch defines TASK_SIZE which depends on test_thread_flag(TIF_32BIT_ADDR) but it doesn't define TASK_SIZE_MAX, so __access_ok() will use TASK_SIZE. Oleg.