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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 EE63FC33C9E for ; Mon, 6 Jan 2020 18:03:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6F9520715 for ; Mon, 6 Jan 2020 18:03:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MRrkj8EI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726735AbgAFSDp (ORCPT ); Mon, 6 Jan 2020 13:03:45 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:44645 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726448AbgAFSDo (ORCPT ); Mon, 6 Jan 2020 13:03:44 -0500 Received: by mail-qt1-f194.google.com with SMTP id t3so43126061qtr.11; Mon, 06 Jan 2020 10:03:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=NXHuuZed9m4gmjDMxbSt8Ydx4KTmpkC7vJID6XaP7I0=; b=MRrkj8EI0gCPmdFxE+7l+GK4uoJ6rM6ez9nHt6AUuGx0FMkXiOZaBPPo6v3ir/4qvC UM5lPvnzAegMqlxcvWBcv3A3h05n6p3fJ4wHTpCTlugRpUV3todEv6atqHe976LnXxna if18JR4BhGt+t0M9PlWIWDBou86TspPSN28Kqbqr919TE6T9gKIMe/E0zIxV3Oq3Tfnm LO0AH25bvTRbBaokmYmmGonA1NFq16uTbNKa5S2pthdQ8j1nL0twPvfvOIY3HlDgZQNg YZUB0rAifbrSZjdksMKGwPQs4JtyBqj9GDLvR3mBRdQiAlt/GQkvWduSfMO9EhkKG5Fy FoYQ== 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=NXHuuZed9m4gmjDMxbSt8Ydx4KTmpkC7vJID6XaP7I0=; b=VezwHh+MIzzxCQGalTuzxr99SNZEgNC8XxVSbBV56MIyvlQkv+7LNisHa866jeX9o0 94nGEkGj5cejiHTRS+5gRElR3k2ZMKt2P16H1XOLPaptyhZvAOERYWH0IfR83znHbXKM NSyp1+rs8rvHEX6R4EbuZKekH3/mHA0yCvFMYlYFQoJ+fVDKQ0Gx/hAJgs3DVGVJVazG ij3LPm/QJVYowTN6ApfvJatJTq0dZprpBSboZOg48Hui2ALcKvRpKOAUydLWHhl7InIq F9E9N7/yZrcDGu71cfQJV2qcmbcSx+/62TnrB/X6xMHvszCy+G+sPb1cexhQzkb1VyKW OCBQ== X-Gm-Message-State: APjAAAUnId8NLkMWS+NoVkwkR6cyzkHFuplSB/95GrLUASK+KCbNJRTw mIBIPCEjHK1Ler5IEW0yMAzNv7cVr28C8vvdmC4= X-Google-Smtp-Source: APXvYqzoJpUI0qTBtGKc5HQQ71R+sejfLNU2IySNvN3xwwd+i3ukSvzyjPMESKmBcjWfEsJ28fSXH9mWzvLYPr9q2Ko= X-Received: by 2002:ac8:5457:: with SMTP id d23mr72628654qtq.93.1578333823652; Mon, 06 Jan 2020 10:03:43 -0800 (PST) MIME-Version: 1.0 References: <20200102172413.654385-1-amanieu@gmail.com> <20200102172413.654385-3-amanieu@gmail.com> <20200102180130.hmpipoiiu3zsl2d6@wittgenstein> <20200106173953.GB9676@willie-the-truck> In-Reply-To: <20200106173953.GB9676@willie-the-truck> From: "Amanieu d'Antras" Date: Mon, 6 Jan 2020 19:03:32 +0100 Message-ID: Subject: Re: [PATCH 2/7] arm64: Implement copy_thread_tls To: Will Deacon Cc: Christian Brauner , Will Deacon , linux-kernel@vger.kernel.org, Christian Brauner , "# 3.4.x" , Linux ARM Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 6, 2020 at 6:39 PM Will Deacon wrote: > I also ran the native and compat selftests but, unfortunately, they all > pass even without this patch. Do you reckon it would be possible to update > them to check the tls pointer? Here's the program I used for testing on arm64. I considered adding it to the selftests but there is no portable way of reading the TLS register on all architectures. #include #include #include #include #define __NR_clone3 435 struct clone_args { uint64_t flags; uint64_t pidfd; uint64_t child_tid; uint64_t parent_tid; uint64_t exit_signal; uint64_t stack; uint64_t stack_size; uint64_t tls; }; #define USE_CLONE3 int main() { printf("Before fork: tp = %p\n", __builtin_thread_pointer()); #ifdef USE_CLONE3 struct clone_args args = { .flags = CLONE_SETTLS, .tls = (uint64_t)__builtin_thread_pointer(), }; int ret = syscall(__NR_clone3, &args, sizeof(args)); #else int ret = syscall(__NR_clone, CLONE_SETTLS, 0, 0, __builtin_thread_pointer(), 0); #endif printf("Fork returned %d, tp = %p\n", ret, __builtin_thread_pointer()); }