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 B3EA8C433B4 for ; Sat, 1 May 2021 07:50:49 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E5593613EC for ; Sat, 1 May 2021 07:50:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5593613EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FXLyH1zqKz301F for ; Sat, 1 May 2021 17:50:47 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) X-Greylist: delayed 1106 seconds by postgrey-1.36 at boromir; Sat, 01 May 2021 17:50:24 AEST Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FXLxr2NVPz2y08 for ; Sat, 1 May 2021 17:50:21 +1000 (AEST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4FXLXP5GqRz9sRr; Sat, 1 May 2021 09:31:49 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9846q1DQgH85; Sat, 1 May 2021 09:31:49 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4FXLXP49fWz9sRq; Sat, 1 May 2021 09:31:49 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id C91938B76F; Sat, 1 May 2021 09:31:48 +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 0LOx1gJ0iR8h; Sat, 1 May 2021 09:31:48 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 6F8F68B763; Sat, 1 May 2021 09:31:47 +0200 (CEST) Subject: Re: [PATCH 1/3] lib: early_string: allow early usage of some string functions From: Christophe Leroy To: Daniel Walker , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, Andrew Morton References: <20210430042217.1198052-1-danielwa@cisco.com> <1929b3a8-f882-c930-4b99-10c6a8f127c7@csgroup.eu> Message-ID: Date: Sat, 1 May 2021 09:31:47 +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: <1929b3a8-f882-c930-4b99-10c6a8f127c7@csgroup.eu> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, xe-linux-external@cisco.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 30/04/2021 à 10:50, Christophe Leroy a écrit : > > > Le 30/04/2021 à 10:47, Christophe Leroy a écrit : >> >> >> 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 > > In fact, should be like in prom_init today: > > #ifdef __EARLY_STRING_ENABLED >     if (dsize >= count) >         return count; > #else >     BUG_ON(dsize >= count); > #endif Thinking about it once more, this BUG_ON() is overkill and should be avoided, see https://www.kernel.org/doc/html/latest/process/deprecated.html Therefore, something like the following would make it: if (dsize >= count) { WARN_ON(!__is_defined(__EARLY_STRING_ENABLED)); return count; } > >> >> >>> + >>> +    dest += dsize; >>> +    count -= dsize; >>> +    if (len >= count) >>> +        len = count-1; >>> +    memcpy(dest, src, len); >>> +    dest[len] = 0; >>> +    return res; >>> +} >>> +EXPORT_SYMBOL(strlcat); >>> +#endif >>> +