From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH] Test case of emulating multibyte NOP Date: Thu, 6 Jun 2013 08:40:32 +0300 Message-ID: <20130606054032.GM4725@redhat.com> References: <1370448172-22960-1-git-send-email-yzt356@gmail.com> <20130605161352.GI4725@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: kvm , Paolo Bonzini To: =?utf-8?B?5p2O5pil5aWHIDxBcnRodXIgQ2h1bnFpIExpPg==?= Return-path: Received: from mx1.redhat.com ([209.132.183.28]:23211 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356Ab3FFFkf convert rfc822-to-8bit (ORCPT ); Thu, 6 Jun 2013 01:40:35 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Jun 06, 2013 at 12:28:16AM +0800, =E6=9D=8E=E6=98=A5=E5=A5=87 <= Arthur Chunqi Li> wrote: > On Thu, Jun 6, 2013 at 12:13 AM, Gleb Natapov wrote= : > > This time the email is perfect :) > > > > On Thu, Jun 06, 2013 at 12:02:52AM +0800, Arthur Chunqi Li wrote: > >> Add multibyte NOP test case to kvm-unit-tests. This version adds t= est cases into x86/realmode.c. This can test one of bugs when booting R= HEL5.9 64-bit. > >> > >> Signed-off-by: Arthur Chunqi Li > >> --- > >> x86/realmode.c | 24 ++++++++++++++++++++++++ > >> 1 file changed, 24 insertions(+) > >> > >> diff --git a/x86/realmode.c b/x86/realmode.c > >> index 981be08..e103ca6 100644 > >> --- a/x86/realmode.c > >> +++ b/x86/realmode.c > >> @@ -1504,6 +1504,29 @@ static void test_fninit(void) > >> report("fninit", 0, fsw =3D=3D 0 && (fcw & 0x103f) =3D=3D 0x= 003f); > >> } > >> > >> +static void test_nopl(void) > >> +{ > >> + MK_INSN(nopl1, ".byte 0x90\n\r"); // 1 byte nop > >> + MK_INSN(nopl2, ".byte 0x66, 0x90\n\r"); // 2 bytes nop > >> + MK_INSN(nopl3, ".byte 0x0f, 0x1f, 0x00\n\r"); // 3 bytes nop > >> + MK_INSN(nopl4, ".byte 0x0f, 0x1f, 0x40, 0x00\n\r"); // 4 byt= es nop > > But all nops below that are not supported in 16 bit mode. You can > > disassemble realmode.elf in 16bit node (objdump -z -d -mi8086 > > x86/realmode.elf) and check yourself. Lets not complicate things fo= r now > > and test only those that are easy to test. > Yes. But what if a 7-bytes nop runs in 16bit mode? Just the same as > https://bugzilla.redhat.com/show_bug.cgi?id=3D967652 >=20 It cannot. In 16 bit mode it is decoded as two instructions: 0f 1f 80 00 00 nopw 0x0(%bx,%si) 00 00 add %al,(%bx,%si) > DR6=3D00000000ffff0ff0 DR7=3D0000000000000400 > EFER=3D0000000000000500 > Code=3D00 00 e9 50 ff ff ff 00 00 00 00 85 d2 74 20 45 31 c0 31 c9 <0= f> > 1f 80 00 00 00 00 0f b6 04 31 41 83 c0 01 88 04 39 48 83 c1 01 41 39 > d0 75 ec 48 89 f8 >=20 > The error code is "0f 1f 80 00 00 00 00", which is a 7-bytes nop. Wil= l > the emulator runs well in that case when booting RHEL5.9 64-bit? >=20 > Arthur >=20 >=20 > > > >> + MK_INSN(nopl5, ".byte 0x0f, 0x1f, 0x44, 0x00, 0x00\n\r"); //= 5 bytes nop > >> + MK_INSN(nopl6, ".byte 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00\n\r= "); // 6 bytes nop > >> + MK_INSN(nopl7, ".byte 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x= 00\n\r"); // 7 bytes nop > >> + MK_INSN(nopl8, ".byte 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x= 00, 0x00\n\r"); // 8 bytes nop > >> + MK_INSN(nopl9, ".byte 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x= 00, 0x00, 0x00\n\r"); // 9 bytes nop > >> + exec_in_big_real_mode(&insn_nopl1); > >> + exec_in_big_real_mode(&insn_nopl2); > >> + exec_in_big_real_mode(&insn_nopl3); > >> + exec_in_big_real_mode(&insn_nopl4); > >> + exec_in_big_real_mode(&insn_nopl5); > >> + exec_in_big_real_mode(&insn_nopl6); > >> + exec_in_big_real_mode(&insn_nopl7); > >> + exec_in_big_real_mode(&insn_nopl8); > >> + exec_in_big_real_mode(&insn_nopl9); > >> + report("nopl", 0, 1); > >> +} > >> + > >> void realmode_start(void) > >> { > >> test_null(); > >> @@ -1548,6 +1571,7 @@ void realmode_start(void) > >> test_xlat(); > >> test_salc(); > >> test_fninit(); > >> + test_nopl(); > >> > >> exit(0); > >> } > >> -- > >> 1.7.9.5 > > > > -- > > Gleb. -- Gleb.