From nobody Fri Dec 19 12:46:26 2025 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 BE435C83F12 for ; Mon, 28 Aug 2023 07:03:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229618AbjH1HDY (ORCPT ); Mon, 28 Aug 2023 03:03:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229610AbjH1HDB (ORCPT ); Mon, 28 Aug 2023 03:03:01 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C43AF9E for ; Mon, 28 Aug 2023 00:02:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1693206178; bh=v5HgZPSe5Z64SEq5cRxK1KbyvNnxfHEB4Vn6IobhnPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hy4j7EOyEj8R3SxeW5Xz4+M6kzD8BAQ5o7g0PbQKnQtcIlAGGrQuQzDGz2VS1xyNT 5dUbip9YMsyjZXvve71U91fMuDGbdettz/WKy4BVucOKIqDOjAl0GOM408MWyRsF/7 uWbpiJKHNiqlohLopwfWA86k0DyGzW/wQXEjSjGXkmM4mQMxKD8/kv+Rfp/YAVTNVW Sk2Y6kiu0CghcG11fKuI9q7FdpJ+tga7pnxNFS2ak7IaW0cOK+s3UWOVFs2IL6afDL 1C7eeAb+TgIavHJz4Y5xhvQ+2aWyvMf9MsknkW78752iln9bup+50mM7uYYG1KvePs dpfeROlyJqO8w== Received: from localhost.localdomain (unknown [182.253.126.208]) by gnuweeb.org (Postfix) with ESMTPSA id C3BA424B200; Mon, 28 Aug 2023 14:02:54 +0700 (WIB) From: Ammar Faizi To: Willy Tarreau , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Cc: Ammar Faizi , Zhangjin Wu , Nicholas Rosenberg , Michael William Jonathan , GNU/Weeb Mailing List , Linux Kernel Mailing List Subject: [PATCH v2 1/1] tools/nolibc: i386: Fix a stack misalign bug on _start Date: Mon, 28 Aug 2023 14:02:40 +0700 Message-Id: <20230828070240.1691921-2-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230828070240.1691921-1-ammarfaizi2@gnuweeb.org> References: <20230828070240.1691921-1-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The ABI mandates that the %esp register must be a multiple of 16 when executing a 'call' instruction. Commit 2ab446336b17 ("tools/nolibc: i386: shrink _start with _start_c") simplified the _start function, but it didn't take care of the %esp alignment, causing SIGSEGV on SSE and AVX programs that use aligned move instruction (e.g., movdqa, movaps, and vmovdqa). The 'and $-16, %esp' aligns the %esp at a multiple of 16. Then 'push %eax' will subtract the %esp by 4; thus, it breaks the 16-byte alignment. Make sure the %esp is correctly aligned after the push by subtracting 12 before the push. Cc: Zhangjin Wu Fixes: 2ab446336b17aad362c6decee29b4efd83a01979 ("tools/nolibc: i386: shrin= k _start with _start_c") Reported-by: Nicholas Rosenberg Acked-by: Thomas Wei=C3=9Fschuh Signed-off-by: Ammar Faizi --- tools/include/nolibc/arch-i386.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i= 386.h index 64415b9fac77f996..8079974424fa18b0 100644 --- a/tools/include/nolibc/arch-i386.h +++ b/tools/include/nolibc/arch-i386.h @@ -167,7 +167,8 @@ void __attribute__((weak, noreturn, optimize("Os", "omi= t-frame-pointer"))) __no_ __asm__ volatile ( "xor %ebp, %ebp\n" /* zero the stack frame = */ "mov %esp, %eax\n" /* save stack pointer to %eax, as arg1 of _sta= rt_c */ - "and $-16, %esp\n" /* last pushed argument must be 16-byte aligne= d */ + "and $-16, %esp\n" /* align stack to 16 bytes = */ + "sub $(16 - 4), %esp\n" /* push %eax breaks 16-byte alignment, so sub = 12 bytes */ "push %eax\n" /* push arg1 on stack to support plain stack m= odes too */ "call _start_c\n" /* transfer to c runtime = */ "hlt\n" /* ensure it does not return = */ --=20 Ammar Faizi