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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 3D0E2C433DF for ; Mon, 17 Aug 2020 20:14:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E978205CB for ; Mon, 17 Aug 2020 20:14:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FqbjGe9U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729240AbgHQUOD (ORCPT ); Mon, 17 Aug 2020 16:14:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726133AbgHQUNz (ORCPT ); Mon, 17 Aug 2020 16:13:55 -0400 Received: from mail-qk1-x744.google.com (mail-qk1-x744.google.com [IPv6:2607:f8b0:4864:20::744]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30092C061389; Mon, 17 Aug 2020 13:13:55 -0700 (PDT) Received: by mail-qk1-x744.google.com with SMTP id 77so16189286qkm.5; Mon, 17 Aug 2020 13:13:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=2iB7Xz00n5+0Lgu+wndRSafBvCLWjlpZRZyNPVeU2aE=; b=FqbjGe9U5+KoOmxxjyJUB/RZzrdUONjZiYMyDKoUkuh/2yHKnD6zT2Uj7I8UbYuYAG QKES7m4drXles2frxuunVXJFU1vO1nTqmKZtt9pWAP++iA9oQf2C6rcqPgkgJq3LFSBX lcHri0k4ctEipOVQzk2ZLIF4Zno7KvX8T8mxizBKLaRryyosyhgMbAVe5l5ZNGawNZcB JMeGxi8/ZTYXacW+5uXhoZSwXrvm3+V8etyM/j7swCB+x8Eyz25aPf+13K1O9qptwy0f Wu+weqYJRxwBupy6n1sgAadO/uIXEAL/BHeBAw1uDn6HckGZAQ45nlUhdDG2KSNvUAI9 41fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:date:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=2iB7Xz00n5+0Lgu+wndRSafBvCLWjlpZRZyNPVeU2aE=; b=j5D2bvwczN7VvQMNm3359TiFjXDcaMiTr8oqJe5WD8PyFtrsgbWEhjJqjzzNmgD8qR f8UoPWozBwCBPKN+B3W18ef8pzDqBCE9kVC1AWEtwzaBgj0+QEVWOC5TXAVybQSjrnU3 gifrBKID06Q+qAMgw9Q+6lz4NknA6OdeqK5h07VauyDfocviKACmCPNalLjfNjEFsl5a uTEiGJRRhsjvaol1qjW7KmjsxzKKFmGSJyxRvobkwoiyEFgjbyLT8ES+wcaskfnzwz2M u9vMt3VcPiMudOTDY9EObXk5qw950Za9813RRqBiK72VixtKILm+cGDMOsrCyWzuPLyu YXaA== X-Gm-Message-State: AOAM530fHNLLhO/nFMbue+akz0cvC97BKHT4kS5r82Tlo2oA/jkvhBov EAem/LSZ+uY3XeHUxLNvVzg= X-Google-Smtp-Source: ABdhPJwcD83COjwoesiJj86XB2SqJAdVYnEaAF0ceFWHGp52ZZZ3SM1gxfEjep5vmUDLeI3v8fGScw== X-Received: by 2002:a37:6cc1:: with SMTP id h184mr14674031qkc.101.1597695234334; Mon, 17 Aug 2020 13:13:54 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id k5sm18742660qke.18.2020.08.17.13.13.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Aug 2020 13:13:53 -0700 (PDT) From: Arvind Sankar X-Google-Original-From: Arvind Sankar Date: Mon, 17 Aug 2020 16:13:51 -0400 To: Nick Desaulniers Cc: Sami Tolvanen , Arvind Sankar , Kees Cook , Sedat Dilek , Fangrui Song , Joe Perches , Andrew Morton , =?utf-8?B?RMOhdmlkIEJvbHZhbnNrw70=?= , Eli Friedman , "# 3.4.x" , Vishal Verma , Dan Williams , Andy Shevchenko , "Joel Fernandes (Google)" , Daniel Axtens , Ingo Molnar , Yury Norov , Alexandru Ardelean , LKML , clang-built-linux , Rasmus Villemoes , Nathan Chancellor Subject: Re: [PATCH v2] lib/string.c: implement stpcpy Message-ID: <20200817201351.GA2246446@rani.riverdale.lan> References: <457a91183581509abfa00575d0392be543acbe07.camel@perches.com> <20200816001917.4krsnrik7hxxfqfm@google.com> <20200816150217.GA1306483@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 17, 2020 at 11:36:49AM -0700, Nick Desaulniers wrote: > > > Though I don't understand the original issue, with -ffreestanding, > > > sprintf shouldn't have been turned into strcpy in the first place. > > Huh? The original issue for this thread is because `-ffreestanding` > *isn't* being used for most targets (oh boy, actually mixed usage by > ARCH. Looks like MIPS, m68k, superH, xtensa, and 32b x86 use it?); and > I'm not suggesting it be used. > Sorry, I meant the issue mentioned in the commit that removed -ffreestanding, not the stpcpy one you're solving now. It says that sprintf got converted into strcpy, which caused failures because back then, strcpy was #define'd to __builtin_strcpy, and the default implementation was actually of a function called __builtin_strcpy o_O, not strcpy. Anyway, that's water under the bridge now. 6edfba1b33c7 ("x86_64: Don't define string functions to builtin") gcc should handle this anyways, and it causes problems when sprintf is turned into strcpy by gcc behind our backs and the C fallback version of strcpy is actually defining __builtin_strcpy