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=2.5 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SORTED_RECIPS,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 Authentication-Results: gnuweeb.org; dmarc=none (p=none dis=none) header.from=tinylab.org Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=43.155.67.158; helo=bg4.exmail.qq.com; envelope-from=falcon@tinylab.org; receiver= Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.155.67.158]) by gnuweeb.org (Postfix) with ESMTPS id 7E03924B1C3 for ; Sat, 26 Aug 2023 22:07:23 +0700 (WIB) X-QQ-mid: bizesmtp67t1693062427tn000v0e Received: from linux-lab-host.localdomain ( [116.30.128.222]) by bizesmtp.qq.com (ESMTP) with id ; Sat, 26 Aug 2023 23:07:05 +0800 (CST) X-QQ-SSF: 01200000000000E0Y000000A0000000 X-QQ-FEAT: 5q30pvLz2ieEBQx0nw4AwVbcsW2lf9AQtedbunJNKIq0umdPrlU1WYxaGQJTB /xLXCQ64QjlcZRbHq7jhW5yGut+QHQxkQLr84/OH3jNGS3VC4CvpOYAXkK3GwhuwTU/bs5S 4CIxMZVwLFJD8lTUd8VJVS0vT/6OK9GGgP92Ibn+qJmHJR06X7qysw0X82SmfEhUSO+4I0F 9PHtDB68M6Acop+iZMlDFXG44X0MXdosR2aJjI6hAHs63iTFNdOnCn0YOwdjZNRaE5Q288R BrM2F0ZzLFMqM7A359j3T2MaoxvUgn3x7XRLUJBgX/18FaEaa0aY3BWk+kdA3XlJdQpIeoV u4oom7NNpcEcKGPaz/KoRX/xYyHsgZ2mpFQ6hzlDnJpa4wFUjMZsCdhVS/rWJRRgzGF/Q5U X-QQ-GoodBg: 0 X-BIZMAIL-ID: 7776601677145500224 From: Zhangjin Wu To: ammarfaizi2@gnuweeb.org Cc: falcon@tinylab.org, gwml@vger.gnuweeb.org, inori@vnlx.org, linux-kernel@vger.kernel.org, linux@weissschuh.net, moe@gnuweeb.org, w@1wt.eu Subject: Re: [PATCH v1 1/1] tools/nolibc: i386: Fix a stack misalign bug on _start Date: Sat, 26 Aug 2023 23:07:04 +0800 Message-Id: <20230826150704.7588-1-falcon@tinylab.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230826141632.1488740-2-ammarfaizi2@gnuweeb.org> References: <20230826141632.1488740-2-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:tinylab.org:qybglogicsvrgz:qybglogicsvrgz5a-1 List-Id: Hi, Ammar, Hi, Nicholas Thanks very much for your report and fixup, sorry for the missing alignment for the new single one push instruction. > The ABI mandates that the %esp register must be a multiple of 16 when > executing a call instruction. > > Commit 2ab446336b17 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). > > Ensure the %esp is a multiple of 16 when executing the call instruction. > > Cc: Zhangjin Wu > Fixes: 2ab446336b17aad362c6decee29b4efd83a01979 ("tools/nolibc: i386: shrink _start with _start_c") > Reported-by: Nicholas Rosenberg > 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..4edf238eeac67aa2 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 $12, %esp\n" /* last pushed argument must be 16-byte aligned */ Ammar, the new call of _start_c() only requires a single push, it pushes the argument and minus %esp by 4, so, the alignment of %esp requires to minus 12 to reserve 16-byte alignment, is this description right? If so, What about further? "and $-16, %esp\n" /* align stack to 16 bytes */ "sub ($16 - $4), %esp" /* the 'push %eax' breaks stack alignment, fix up it */ Thanks, Zhangjin Wu > "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