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=-1.0 required=3.0 tests=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 87692C32792 for ; Mon, 30 Sep 2019 12:06:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 57F2A20815 for ; Mon, 30 Sep 2019 12:06:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="a1IcMkg7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730319AbfI3MGU (ORCPT ); Mon, 30 Sep 2019 08:06:20 -0400 Received: from conssluserg-01.nifty.com ([210.131.2.80]:31243 "EHLO conssluserg-01.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728214AbfI3MGT (ORCPT ); Mon, 30 Sep 2019 08:06:19 -0400 Received: from mail-vk1-f172.google.com (mail-vk1-f172.google.com [209.85.221.172]) (authenticated) by conssluserg-01.nifty.com with ESMTP id x8UC5mg4011579; Mon, 30 Sep 2019 21:05:49 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-01.nifty.com x8UC5mg4011579 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1569845150; bh=DN+I4wpsZvAFccyMFSwXymsfa8keAnBOQLk85QFPIzE=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=a1IcMkg7e3F/Lb/SPd8AjuqIs94nfZNAtbzuXBAjUyijbwCpczwfGBEm2/tHc6MOe RilHMU/70eAqFpuvaC3qcIROm77Id9H/rCSRc9SqyJ63HrxTssFLYQC20RWMF+ejOj DXgGPvZ8AXareBeeJTqY+oHxsJgsXi+xBMHOcvhpggBTCgB7f8vnUiFWVhWyPD8dYu YreMIYWY+zHl/c5VmIyixTLs7NlX0K0QCNCLuPphm8UjhOF4mxsWxIdF0D45b/SLzp Xly2/UNYxOjGzsQN+dfNAJPClfSSaI76TO00xobqxcxbm6dKC3ApHKiveOB+XtFQ7t kAbl6gOVBE5nQ== X-Nifty-SrcIP: [209.85.221.172] Received: by mail-vk1-f172.google.com with SMTP id q192so1296990vka.12; Mon, 30 Sep 2019 05:05:48 -0700 (PDT) X-Gm-Message-State: APjAAAVkGo/L7PGljLnALmg4ibIc/pZcRM2Pve8uP7hLVbguMeURHd9I KzUXTGeQb/MNjSKpeFeA0aRIkI2No7T/KoWRyMQ= X-Google-Smtp-Source: APXvYqzHTcupPhE7fYtEX+jAQWcOhQ0jzTGnC4NcznjraANJ1alL1Wv6gfBjsFHHPncsy8kWiZUyQovTE/NlKyLzYEg= X-Received: by 2002:a1f:60c2:: with SMTP id u185mr8338504vkb.0.1569845147622; Mon, 30 Sep 2019 05:05:47 -0700 (PDT) MIME-Version: 1.0 References: <20190830034304.24259-1-yamada.masahiro@socionext.com> <20190930112636.vx2qxo4hdysvxibl@willie-the-truck> In-Reply-To: <20190930112636.vx2qxo4hdysvxibl@willie-the-truck> From: Masahiro Yamada Date: Mon, 30 Sep 2019 21:05:11 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] compiler: enable CONFIG_OPTIMIZE_INLINING forcibly To: Will Deacon Cc: Linus Torvalds , Nick Desaulniers , Nicolas Saenz Julienne , Andrew Morton , Ingo Molnar , Borislav Petkov , Miguel Ojeda , linux-arch , LKML , Catalin Marinas , Russell King , Stefan Wahren , Kees Cook 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, Sep 30, 2019 at 8:26 PM Will Deacon wrote: > > On Fri, Sep 27, 2019 at 03:38:44PM -0700, Linus Torvalds wrote: > > On Fri, Sep 27, 2019 at 3:08 PM Nick Desaulniers > > wrote: > > > > > > So get_user() was passed a bad value/pointer from userspace? Do you > > > know which of the tree calls to get_user() from sock_setsockopt() is > > > failing? (It's not immediately clear to me how this patch is at > > > fault, vs there just being a bug in the source somewhere). > > > > Based on the error messages, the SO_PASSCRED ones are almost certainly > > from the get_user() in net/core/sock.c: sock_setsockopt(), which just > > does > > > > if (optlen < sizeof(int)) > > return -EINVAL; > > > > if (get_user(val, (int __user *)optval)) > > return -EFAULT; > > > > valbool = val ? 1 : 0; > > > > but it's the other messages imply that a lot of other cases are > > failing too (ie the "Failed to bind netlink socket" is, according to > > google, a bind() that fails with the same EFAULT error). > > > > There are probably even more failures that happen elsewhere and just > > don't even syslog the fact. I'd guess that all get_user() calls just > > fail, and those are the ones that happen to get printed out. > > > > Now, _why_ it would fail, I have ni idea. There are several inlines in > > the arm uaccess.h file, and it depends on other headers like > > with more inlines still - eg get/set_domain() etc. > > > > Soem of that code is pretty subtle. They have fixed register usage > > (but the asm macros actually check them). And the inline asms clobber > > the link register, but they do seem to clearly _state_ that they > > clobber it, so who knows. > > > > Just based on the EFAULT, I'd _guess_ that it's some interaction with > > the domain access control register (so that get/set_domain() thing). > > But I'm not even sure that code is enabled for the Rpi2, so who > > knows.. > > FWIW, we've run into issues with CONFIG_OPTIMIZE_INLINING and local > variables marked as 'register' where GCC would do crazy things and end > up corrupting data, so I suspect the use of fixed registers in the arm > uaccess functions is hitting something similar: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91111 No. Not similar at all. I fixed it already. See https://lore.kernel.org/patchwork/patch/1132459/ The problems are fixable by writing correct code. I think we discussed this already. - There is nothing arch-specific in CONFIG_OPTIMIZE_INLINING - 'inline' is just a hint. It does not guarantee function inlining. This is standard. - The kernel macrofies 'inline' to add __attribute__((__always_inline__)) This terrible hack must end. - __attribute__((__always_inline__)) takes aways compiler's freedom, and prevents it from optimizing the code for -O2, -Os, or whatever. > Although this particular case couldn't be reproduced with GCC 9, prior > versions of the compiler get it wrong so I'm very much opposed to enabling > CONFIG_OPTIMIZE_INLINING by default on arm/arm64. > > Will -- Best Regards Masahiro Yamada