From patchwork Sat Jul 8 15:29:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhangjin Wu X-Patchwork-Id: 13305682 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C43CEB64DA for ; Sat, 8 Jul 2023 15:30:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230418AbjGHPaM (ORCPT ); Sat, 8 Jul 2023 11:30:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229726AbjGHPaL (ORCPT ); Sat, 8 Jul 2023 11:30:11 -0400 Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.154.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78DFF90; Sat, 8 Jul 2023 08:30:09 -0700 (PDT) X-QQ-mid: bizesmtp90t1688830199tddli4lm Received: from linux-lab-host.localdomain ( [116.30.131.119]) by bizesmtp.qq.com (ESMTP) with id ; Sat, 08 Jul 2023 23:29:58 +0800 (CST) X-QQ-SSF: 01200000000000D0W000000A0000000 X-QQ-FEAT: eSZ1CZgv+JDNSYVWcvAqpj0rMV65FuCWvkiqEsX0QCaJ3cmGvGHwqt4FW1NPz xtLYKx4fWntTwjgdLuKBjSAmdBqltgnFcnpV0Gg+dSUFOBuhWgGtMIVtlDJuRSOakTaDPyf DteElzUduQbDJaKPkaiv65kbJIwnbKHkk9XhbF7riP1SVSVYoxY855+ZD2A+7Kyh5RALGtG zeeesVIfP5H0OAey6/2Pp+ARRSKgkAwVv0n0wkl3AZDqzEyuojwi0WP8cSU2snSHpbwpFMf C/QtfST4aIERx7pL/R9uECvdoTwV9p5F2Zo/LtJSLRMdjKmijl9YEoGocgpClxQWlw6II3G 0TZNWf1ltkWlZULHAwSeTkDHf2JIuhfDfKj0rx2TIG3R52KWmXc2oQ7zS748Q== X-QQ-GoodBg: 0 X-BIZMAIL-ID: 10107616674853176489 From: Zhangjin Wu To: w@1wt.eu Cc: falcon@tinylab.org, arnd@arndb.de, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, thomas@t-8ch.de Subject: [PATCH v2 04/12] tools/nolibc: crt.h: add _start_c Date: Sat, 8 Jul 2023 23:29:58 +0800 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:tinylab.org:qybglogicsvrgz:qybglogicsvrgz5a-1 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org As the environ and _auxv support added for nolibc, the assembly _start function becomes more and more complex and therefore makes the porting of nolibc to new architectures harder and harder. To simplify portability, this c version of _start_c() is added to do most of the assembly start operations in C, which reduces the complexity a lot and will eventually simplify the porting of nolibc to the new architectures. The new _start_c() only requires a stack pointer argument, it will find argv, envp and _auxv for us, and then call main(), finally, it exit() with main's return status. With this new _start_c(), the future new architectures only require to add very few assembly instructions. Signed-off-by: Zhangjin Wu --- tools/include/nolibc/crt.h | 44 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h index 221b7c5346ca..b269294e9664 100644 --- a/tools/include/nolibc/crt.h +++ b/tools/include/nolibc/crt.h @@ -13,4 +13,48 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); +int main(int argc, char *argv[], char **envp); +static void exit(int); + +void _start_c(long *sp) +{ + int argc, i; + char **argv; + char **envp; + + /* + * sp : argc <-- argument count, required by main() + * argv: argv[0] <-- argument vector, required by main() + * argv[1] + * ... + * argv[argc-1] + * null + * envp: envp[0] <-- environment variables, required by main() and getenv() + * envp[1] + * ... + * null + * _auxv: auxv[0] <-- auxiliary vector, required by getauxval() + * auxv[1] + * ... + * null + */ + + /* assign argc and argv */ + argc = sp[0]; + argv = (void *)(sp + 1); + + /* find envp */ + envp = argv + argc + 1; + environ = envp; + + /* find auxv */ + i = 0; + while (envp[i]) + i++; + _auxv = (void *)(envp + i + 1); + + /* go to application */ + exit(main(argc, argv, envp)); +} + #endif /* _NOLIBC_CRT_H */