Re: [PATCH] Test case of emulating multibyte NOP

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On Thu, Jun 6, 2013 at 3:17 PM, 李春奇 <Arthur Chunqi Li> <yzt356@xxxxxxxxx> wrote:
> On Thu, Jun 6, 2013 at 3:02 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>> On Thu, Jun 06, 2013 at 02:49:14PM +0800, 李春奇 <Arthur Chunqi Li> wrote:
>>> On Thu, Jun 6, 2013 at 1:40 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>>> > On Thu, Jun 06, 2013 at 12:28:16AM +0800, 李春奇 <Arthur Chunqi Li> wrote:
>>> >> On Thu, Jun 6, 2013 at 12:13 AM, Gleb Natapov <gleb@xxxxxxxxxx> 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 test cases into x86/realmode.c. This can test one of bugs when booting RHEL5.9 64-bit.
>>> >> >>
>>> >> >> Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
>>> >> >> ---
>>> >> >>  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 == 0 && (fcw & 0x103f) == 0x003f);
>>> >> >>  }
>>> >> >>
>>> >> >> +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 bytes 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 for 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=967652
>>> >>
>>> > 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)
>>> >
>>> OK, I will just test the first four nop instructions. Should I commit
>>> another patch?
>>>
>> Yes, all others will have to go into emulator.c.
> You mean I need also add another test for nopl5~nop9 in emulator.c
> with the "trick" emulator mode?
> I will commit a modified one for realmode.c since some other works
> should be done in emulator.c.
Since we need to place some relevant codes in emulator.c, why don't we
place all the tests in emulator.c?

Arthur.

>
>>
>>> Arthur.
>>>
>>> >> DR6=00000000ffff0ff0 DR7=0000000000000400
>>> >> EFER=0000000000000500
>>> >> Code=00 00 e9 50 ff ff ff 00 00 00 00 85 d2 74 20 45 31 c0 31 c9 <0f>
>>> >> 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
>>> >>
>>> >> The error code is "0f 1f 80 00 00 00 00", which is a 7-bytes nop. Will
>>> >> the emulator runs well in that case when booting RHEL5.9 64-bit?
>>> >>
>>> >> Arthur
>>> >>
>>> >>
>>> >> >
>>> >> >> +     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, 0x00\n\r"); // 7 bytes nop
>>> >> >> +     MK_INSN(nopl8, ".byte 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00\n\r"); // 8 bytes nop
>>> >> >> +     MK_INSN(nopl9, ".byte 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 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.
>>
>> --
>>                         Gleb.
>
>
>
> --
> Arthur Chunqi Li
> Department of Computer Science
> School of EECS
> Peking University
> Beijing, China



--
Arthur Chunqi Li
Department of Computer Science
School of EECS
Peking University
Beijing, China
--
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