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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 891AFC4332E for ; Wed, 3 Mar 2021 20:58:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DF1764E87 for ; Wed, 3 Mar 2021 20:58:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1838262AbhCCS7p (ORCPT ); Wed, 3 Mar 2021 13:59:45 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:61453 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234278AbhCCSVZ (ORCPT ); Wed, 3 Mar 2021 13:21:25 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4DrLpz2xdqz9tylR; Wed, 3 Mar 2021 18:39:39 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id YBZwzXhxA9In; Wed, 3 Mar 2021 18:39:39 +0100 (CET) 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 4DrLpz09Xkz9tylQ; Wed, 3 Mar 2021 18:39:39 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 264978B7E8; Wed, 3 Mar 2021 18:39:39 +0100 (CET) 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 oNwRvWSyIn_a; Wed, 3 Mar 2021 18:39:39 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 609DB8B7E6; Wed, 3 Mar 2021 18:39:38 +0100 (CET) Subject: Re: [PATCH v2 1/7] cmdline: Add generic function to build command line. To: Will Deacon Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , danielwa@cisco.com, robh@kernel.org, daniel@gimpelevich.san-francisco.ca.us, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, devicetree@vger.kernel.org References: <20210303172810.GA19713@willie-the-truck> From: Christophe Leroy Message-ID: Date: Wed, 3 Mar 2021 18:38:16 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210303172810.GA19713@willie-the-truck> 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 03/03/2021 à 18:28, Will Deacon a écrit : > On Tue, Mar 02, 2021 at 05:25:17PM +0000, Christophe Leroy wrote: >> This code provides architectures with a way to build command line >> based on what is built in the kernel and what is handed over by the >> bootloader, based on selected compile-time options. >> >> Signed-off-by: Christophe Leroy >> --- >> include/linux/cmdline.h | 62 +++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 62 insertions(+) >> create mode 100644 include/linux/cmdline.h >> >> diff --git a/include/linux/cmdline.h b/include/linux/cmdline.h >> new file mode 100644 >> index 000000000000..ae3610bb0ee2 >> --- /dev/null >> +++ b/include/linux/cmdline.h >> @@ -0,0 +1,62 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#ifndef _LINUX_CMDLINE_H >> +#define _LINUX_CMDLINE_H >> + >> +static __always_inline size_t cmdline_strlen(const char *s) >> +{ >> + const char *sc; >> + >> + for (sc = s; *sc != '\0'; ++sc) >> + ; /* nothing */ >> + return sc - s; >> +} >> + >> +static __always_inline size_t cmdline_strlcat(char *dest, const char *src, size_t count) >> +{ >> + size_t dsize = cmdline_strlen(dest); >> + size_t len = cmdline_strlen(src); >> + size_t res = dsize + len; >> + >> + /* This would be a bug */ >> + if (dsize >= count) >> + return count; >> + >> + dest += dsize; >> + count -= dsize; >> + if (len >= count) >> + len = count - 1; >> + memcpy(dest, src, len); >> + dest[len] = 0; >> + return res; >> +} > > Why are these needed instead of using strlen and strlcat directly? Because on powerpc (at least), it will be used in prom_init, it is very early in the boot and KASAN shadow memory is not set up yet so calling generic string functions would crash the board. > >> +/* >> + * This function will append a builtin command line to the command >> + * line provided by the bootloader. Kconfig options can be used to alter >> + * the behavior of this builtin command line. >> + * @dest: The destination of the final appended/prepended string. >> + * @src: The starting string or NULL if there isn't one. Must not equal dest. >> + * @length: the length of dest buffer. >> + */ >> +static __always_inline void cmdline_build(char *dest, const char *src, size_t length) >> +{ >> + if (length <= 0) >> + return; >> + >> + dest[0] = 0; >> + >> +#ifdef CONFIG_CMDLINE >> + if (IS_ENABLED(CONFIG_CMDLINE_FORCE) || !src || !src[0]) { >> + cmdline_strlcat(dest, CONFIG_CMDLINE, length); >> + return; >> + } >> +#endif > > CONFIG_CMDLINE_FORCE implies CONFIG_CMDLINE, and even if it didn't, > CONFIG_CMDLINE is at worst an empty string. Can you drop the #ifdef? Ah yes, since cbe46bd4f510 ("powerpc: remove CONFIG_CMDLINE #ifdef mess") it is feasible. I can change that now. > >> + if (dest != src) >> + cmdline_strlcat(dest, src, length); >> +#ifdef CONFIG_CMDLINE >> + if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) && sizeof(CONFIG_CMDLINE) > 1) >> + cmdline_strlcat(dest, " " CONFIG_CMDLINE, length); >> +#endif > > Likewise, but also I'm not sure why the sizeof() is required. It is to avoid adding a white space at the end of the command line when CONFIG_CMDLINE is empty. But maybe it doesn't matter ? Christophe