From patchwork Wed Jul 12 09:17:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Zhangjin Wu X-Patchwork-Id: 702106 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 4EDB1C0015E for ; Wed, 12 Jul 2023 09:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232461AbjGLJSA (ORCPT ); Wed, 12 Jul 2023 05:18:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34716 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231600AbjGLJRw (ORCPT ); Wed, 12 Jul 2023 05:17:52 -0400 Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.154.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56CAB11D; Wed, 12 Jul 2023 02:17:50 -0700 (PDT) X-QQ-mid: bizesmtp62t1689153460t6fqn0jb Received: from linux-lab-host.localdomain ( [116.30.126.249]) by bizesmtp.qq.com (ESMTP) with id ; Wed, 12 Jul 2023 17:17:39 +0800 (CST) X-QQ-SSF: 01200000000000D0W000000A0000000 X-QQ-FEAT: k0mQ4ihyJQOSubvL2shrPA/LW4atE5uOf3i0CK3EnGdQf0viNxC21BnUmaM3X HwVGiywAmFeUbqHVOieSjk+LDTytitz9TsRFkNTe2ErraPTqLYFx9dJuD2UemllBPmqYHEz 9p1w2Tz0tz8jgvM/Sx/SYPYxU5LHY2ni5EdU3M5C6tSZpyFaoa5FzsSQkMcCutoy8UvdCRg QlR7mP6Mo0Dc0PVgRrFH0/1vHBBde+PiAh1IqMyilOioHaNX8k6gpTR46/wjL9u2Ch1aHDk xXASOab4L2E9M7TKSK4ciHT0LYiBKp91+4OdVJ4oWfyVsiwjRIrnF++PmV2EWvsuTYVBkwh DIAcdZOcyjnn3W4ia5tN9uainmlOCBT/Lt9dgBJTkwNPGDCXqImvd8w0X0Z4ySEQ5ceDNH3 RTdEGLLEdTM= X-QQ-GoodBg: 0 X-BIZMAIL-ID: 4436459021916993005 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, =?utf-8?q?Thomas_Wei?= =?utf-8?q?=C3=9Fschuh?= Subject: [PATCH v3 02/11] tools/nolibc: add new crt.h with _start_c Date: Wed, 12 Jul 2023 17:17:39 +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. As suggested by Thomas, users may use a different signature of main (e.g. void main(void)), a _nolibc_main alias is added for main to silence the warning about potential conflicting types. Suggested-by: Thomas Weißschuh Link: https://lore.kernel.org/lkml/90fdd255-32f4-4caf-90ff-06456b53dac3@t-8ch.de/ Signed-off-by: Zhangjin Wu --- tools/include/nolibc/Makefile | 1 + tools/include/nolibc/crt.h | 59 +++++++++++++++++++++++++++++++++++ 2 files changed, 60 insertions(+) create mode 100644 tools/include/nolibc/crt.h diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile index 64d67b080744..909b6eb500fe 100644 --- a/tools/include/nolibc/Makefile +++ b/tools/include/nolibc/Makefile @@ -27,6 +27,7 @@ nolibc_arch := $(patsubst arm64,aarch64,$(ARCH)) arch_file := arch-$(nolibc_arch).h all_files := \ compiler.h \ + crt.h \ ctype.h \ errno.h \ nolibc.h \ diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h new file mode 100644 index 000000000000..f9db2389acd2 --- /dev/null +++ b/tools/include/nolibc/crt.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ +/* + * C Run Time support for NOLIBC + * Copyright (C) 2023 Zhangjin Wu + */ + +#ifndef _NOLIBC_CRT_H +#define _NOLIBC_CRT_H + +char **environ __attribute__((weak)); +const unsigned long *_auxv __attribute__((weak)); + +typedef int (_nolibc_main_fn)(int, char **, char **); +static void exit(int); + +void _start_c(long *sp) +{ + int argc, i; + char **argv; + char **envp; + /* silence potential warning: conflicting types for 'main' */ + _nolibc_main_fn _nolibc_main __asm__ ("main"); + + /* + * 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(_nolibc_main(argc, argv, envp)); +} + +#endif /* _NOLIBC_CRT_H */