From patchwork Sat Jul 15 18:18:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Zhangjin Wu X-Patchwork-Id: 13314586 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 30F7AC001B0 for ; Sat, 15 Jul 2023 18:19:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230014AbjGOSTI (ORCPT ); Sat, 15 Jul 2023 14:19:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbjGOSTH (ORCPT ); Sat, 15 Jul 2023 14:19:07 -0400 Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.154.54.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DDF426AF; Sat, 15 Jul 2023 11:19:05 -0700 (PDT) X-QQ-mid: bizesmtp82t1689445135tgk85grb Received: from linux-lab-host.localdomain ( [119.123.131.162]) by bizesmtp.qq.com (ESMTP) with id ; Sun, 16 Jul 2023 02:18:54 +0800 (CST) X-QQ-SSF: 01200000002000D0W000B00A0000000 X-QQ-FEAT: 7jw2iSiCazq340DjDdEZiMhlBe2vl+0NITWIEc5WkzpS4tH5riGZQoC3SIEqa SsnIvE5sirfAViFzUf4xtboEfVBzLVmCgo2VzbvbND5R9PvmD4iX3xV1ZEA+boiNZE8of4h ELzEHCOXeDggBwc6UDlbbjCfKcEiL432bL7HQqN/erfXNmi6yHC8hyroz4DhxjViDYqZXa3 79VFtvadw2lfISIZp+TWh/Xz16Z15HiJdR6V6IgUNgeX5GIq9fs7rLcczeFopDZCkRrpkGs 6aPZTGSs6RtjkEH5//KOpARzRzGXrZ6qkNsKHWqfoczMIdqskxL/rzRR/5pIxcMvkStBbio pQIRac8+WKwWg1b0F2fDLuRmKBo/1HAnKv0klQ8whW2ITk6KvVSri3sXp7GtmPpPxb1vI8T X-QQ-GoodBg: 0 X-BIZMAIL-ID: 12656723689235740385 From: Zhangjin Wu To: w@1wt.eu Cc: arnd@arndb.de, falcon@tinylab.org, 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 v4 02/18] tools/nolibc: fix up startup failures for -O0 under gcc < 11.1.0 Date: Sun, 16 Jul 2023 02:18:54 +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 gcc doc [1] shows: Most optimizations are completely disabled at -O0 or if an -O level is not set on the command line, even if individual optimization flags are specified. Test result [2] shows, gcc>=11.1.0 deviates from the above description, but before gcc 11.1.0, "-O0" still forcely uses frame pointer in the _start function even if the individual optimize("omit-frame-pointer") flag is specified. The frame pointer related operations will change the stack pointer (e.g. In x86_64, an extra "push %rbp" will be inserted at the beginning of _start) and make it differs from the one we expected, as a result, break the whole startup function. To fix up this issue, as suggested by Thomas, the individual "Os" and "omit-frame-pointer" optimize flags are used together on _start function to disable frame pointer completely even if the -O0 is set on the command line. [1]: https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html [2]: https://lore.kernel.org/lkml/20230714094723.140603-1-falcon@tinylab.org/ Suggested-by: Thomas Weißschuh Link: https://lore.kernel.org/lkml/34b21ba5-7b59-4b3b-9ed6-ef9a3a5e06f7@t-8ch.de/ Fixes: 7f8548589661 ("tools/nolibc: make compiler and assembler agree on the section around _start") Signed-off-by: Zhangjin Wu --- tools/include/nolibc/arch-aarch64.h | 2 +- tools/include/nolibc/arch-arm.h | 2 +- tools/include/nolibc/arch-i386.h | 2 +- tools/include/nolibc/arch-loongarch.h | 2 +- tools/include/nolibc/arch-mips.h | 2 +- tools/include/nolibc/arch-riscv.h | 2 +- tools/include/nolibc/arch-s390.h | 2 +- tools/include/nolibc/arch-x86_64.h | 2 +- 8 files changed, 8 insertions(+), 8 deletions(-) diff --git a/tools/include/nolibc/arch-aarch64.h b/tools/include/nolibc/arch-aarch64.h index 6151be6cd7a9..21e9482a4235 100644 --- a/tools/include/nolibc/arch-aarch64.h +++ b/tools/include/nolibc/arch-aarch64.h @@ -175,7 +175,7 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( #ifdef _NOLIBC_STACKPROTECTOR diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h index 5b12b6e1c83e..4451bef5f94d 100644 --- a/tools/include/nolibc/arch-arm.h +++ b/tools/include/nolibc/arch-arm.h @@ -225,7 +225,7 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( #ifdef _NOLIBC_STACKPROTECTOR diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h index 35680b4a25d4..4c94a81e860f 100644 --- a/tools/include/nolibc/arch-i386.h +++ b/tools/include/nolibc/arch-i386.h @@ -190,7 +190,7 @@ const unsigned long *_auxv __attribute__((weak)); * 2) The deepest stack frame should be set to zero * */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( #ifdef _NOLIBC_STACKPROTECTOR diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h index ada5a69e3fcc..590155a4e543 100644 --- a/tools/include/nolibc/arch-loongarch.h +++ b/tools/include/nolibc/arch-loongarch.h @@ -167,7 +167,7 @@ const unsigned long *_auxv __attribute__((weak)); #endif /* startup code */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( #ifdef _NOLIBC_STACKPROTECTOR diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h index dd0f12131b55..d3f0bf4c4245 100644 --- a/tools/include/nolibc/arch-mips.h +++ b/tools/include/nolibc/arch-mips.h @@ -205,7 +205,7 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code, note that it's called __start on MIPS */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector __start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector __start(void) { __asm__ volatile ( /*".set nomips16\n"*/ diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h index 1dd7083c2ac8..322c96f4acdb 100644 --- a/tools/include/nolibc/arch-riscv.h +++ b/tools/include/nolibc/arch-riscv.h @@ -180,7 +180,7 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( ".option push\n" diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h index 8254caff8bfa..587cc91295fa 100644 --- a/tools/include/nolibc/arch-s390.h +++ b/tools/include/nolibc/arch-s390.h @@ -166,7 +166,7 @@ char **environ __attribute__((weak)); const unsigned long *_auxv __attribute__((weak)); /* startup code */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( "lg %r2,0(%r15)\n" /* argument count */ diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h index fb00ab2e9274..5e950a04bc77 100644 --- a/tools/include/nolibc/arch-x86_64.h +++ b/tools/include/nolibc/arch-x86_64.h @@ -190,7 +190,7 @@ const unsigned long *_auxv __attribute__((weak)); * 2) The deepest stack frame should be zero (the %rbp). * */ -void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void) +void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( #ifdef _NOLIBC_STACKPROTECTOR