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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 D2683C433ED for ; Fri, 30 Apr 2021 08:47:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A288C6140C for ; Fri, 30 Apr 2021 08:47:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231181AbhD3Isa (ORCPT ); Fri, 30 Apr 2021 04:48:30 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:39929 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229507AbhD3Is3 (ORCPT ); Fri, 30 Apr 2021 04:48:29 -0400 Received: from localhost (mailhub3.si.c-s.fr [192.168.12.233]) by localhost (Postfix) with ESMTP id 4FWmGN0sRgz9wct; Fri, 30 Apr 2021 10:47:40 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Sa6dCHscddjg; Fri, 30 Apr 2021 10:47:40 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4FWmGM728Qz9wc9; Fri, 30 Apr 2021 10:47:39 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id DF53F8B87E; Fri, 30 Apr 2021 10:47:39 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id EiSgWgqkncLp; Fri, 30 Apr 2021 10:47:39 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 602258B87A; Fri, 30 Apr 2021 10:47:39 +0200 (CEST) Subject: Re: [PATCH 1/3] lib: early_string: allow early usage of some string functions To: Daniel Walker , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, Andrew Morton Cc: xe-linux-external@cisco.com, linux-kernel@vger.kernel.org References: <20210430042217.1198052-1-danielwa@cisco.com> From: Christophe Leroy Message-ID: Date: Fri, 30 Apr 2021 10:47:39 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <20210430042217.1198052-1-danielwa@cisco.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 30/04/2021 à 06:22, Daniel Walker a écrit : > This systems allows some string functions to be moved into > lib/early_string.c and they will be prepended with "early_" and compiled > without debugging like KASAN. > > This is already done on x86 for, > "AMD Secure Memory Encryption (SME) support" > > and on powerpc prom_init.c , and EFI's libstub. > > The AMD memory feature disabled KASAN for all string functions, and > prom_init.c and efi libstub implement their own versions of the > functions. > > This implementation allows sharing of the string functions without > removing the debugging features for the whole system. This looks good. I prefer that rather than the way you proposed to do it two years ago. Only one problem, see below. > +size_t strlcat(char *dest, const char *src, size_t count) > +{ > + size_t dsize = strlen(dest); > + size_t len = strlen(src); > + size_t res = dsize + len; > + > + /* This would be a bug */ > + BUG_ON(dsize >= count); powerpc is not ready to handle BUG_ON() in when in prom_init. Can you do: #ifndef __EARLY_STRING_ENABLED BUG_ON(dsize >= count); #endif > + > + dest += dsize; > + count -= dsize; > + if (len >= count) > + len = count-1; > + memcpy(dest, src, len); > + dest[len] = 0; > + return res; > +} > +EXPORT_SYMBOL(strlcat); > +#endif > +