From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-1.2 required=5.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,URIBL_BLOCKED, URIBL_DBL_BLOCKED_OPENDNS autolearn=ham autolearn_force=no version=3.4.6 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: 8bit List-Id: 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: shrink _start with _start_c") Reported-by: Nicholas Rosenberg Acked-by: Thomas Weißschuh 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-i386.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", "omit-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 _start_c */ - "and $-16, %esp\n" /* last pushed argument must be 16-byte aligned */ + "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 modes too */ "call _start_c\n" /* transfer to c runtime */ "hlt\n" /* ensure it does not return */ -- Ammar Faizi