Very weird. The emulations now aren't at the same address as before either
(0xd4c3 rather than 0xd71b). Is the *only* difference that you added these
printf()s -- is it at all possible that the guest is executing down a
different path here for other reasons? If it's really down to the printf()s
then I guess you'll have to shuffle/remove printf()s to get the old
behaviour back.
-- Keir
On 7/8/07 12:35, "Brady Chen" <chenchp@xxxxxxxxx> wrote:
> it's strange:
> if i add these prints, i get " Unknown opcode", not "trap".
> ===added printf
> [root@localhost firmware]# hg diff -p vmxassist/vm86.c
> diff -r 6f18f5bdeea3 tools/firmware/vmxassist/vm86.c
> --- a/tools/firmware/vmxassist/vm86.c Mon Aug 06 15:33:42 2007 +0100
> +++ b/tools/firmware/vmxassist/vm86.c Tue Aug 07 19:33:55 2007 +0800
> @@ -40,7 +40,7 @@ static struct regs saved_rm_regs;
> static struct regs saved_rm_regs;
>
> #ifdef DEBUG
> -int traceset = 0;
> +int traceset = ~0;
>
> char *states[] = {
> "<VM86_REAL>",
> @@ -128,6 +128,7 @@ address(struct regs *regs, unsigned seg,
> unsigned seg_base, seg_limit;
> unsigned entry_low, entry_high;
>
> + printf("f 1\n");
> if (seg == 0) {
> if (mode == VM86_REAL || mode == VM86_REAL_TO_PROTECTED)
> return off;
> @@ -135,12 +136,16 @@ address(struct regs *regs, unsigned seg,
> panic("segment is zero, but not in real mode!\n");
> }
>
> + printf("f 2\n");
> if (mode == VM86_REAL || seg > oldctx.gdtr_limit ||
> (mode == VM86_REAL_TO_PROTECTED && regs->cs == seg))
> return ((seg & 0xFFFF) << 4) + off;
>
> + printf("f 3\n");
> gdt_phys_base = guest_linear_to_phys(oldctx.gdtr_base);
> + printf("f 4\n");
> if (gdt_phys_base != (uint32_t)gdt_phys_base) {
> + printf("f 5\n");
> printf("gdt base address above 4G\n");
> cpuid_addr_value(gdt_phys_base + 8 * (seg >> 3), &entry);
> } else
> @@ -152,14 +157,17 @@ address(struct regs *regs, unsigned seg,
> seg_base = (entry_high & 0xFF000000) | ((entry >> 16) & 0xFFFFFF);
> seg_limit = (entry_high & 0xF0000) | (entry_low & 0xFFFF);
>
> + printf("f 6\n");
> if (entry_high & 0x8000 &&
> ((entry_high & 0x800000 && off >> 12 <= seg_limit) ||
> (!(entry_high & 0x800000) && off <= seg_limit)))
> return seg_base + off;
> + printf("f 7\n");
>
> panic("should never reach here in function address():\n\t"
> "entry=0x%08x%08x, mode=%d, seg=0x%08x, offset=0x%08x\n",
> entry_high, entry_low, mode, seg, off);
> + printf("f 8\n");
>
> return 0;
> }
> @@ -286,6 +294,7 @@ fetch8(struct regs *regs)
> unsigned addr = address(regs, regs->cs, MASK16(regs->eip));
>
> regs->eip++;
> + printf("f 9\n");
> return read8(addr);
> }
>
> ===output when add many printf
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) addr32addr32f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: f 9
> (XEN) HVM12: f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) data32data32f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: f 9
> (XEN) HVM12: f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) opc 0x83opc 0xD7704f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: Unknown opcode at 0D00:04C3=0xD4C3
> (XEN) HVM12: Halt called from %eip 0xD3B4A
>
> On 8/7/07, Brady Chen <chenchp@xxxxxxxxx> wrote:
>> Hi, yes, it's crashed in fetch8. it's very slow after I add this print info.
>> the main function of fetch8 seems to be address(). seems crashed in
>> address().
>>
>> (XEN) HVM7: after write16 of movw
>> (XEN) HVM7: top of opcode
>> (XEN) HVM7: Before fetch8
>> (XEN) HVM7: eax 7E80 ecx 2D1B edx 0 ebx 404E
>> (XEN) HVM7: esp D76F4 ebp 1FF0 esi 7BE edi C37FE
>> (XEN) HVM7: trapno D errno 0
>> (XEN) HVM7: eip 71F cs D00 eflags 33206
>> (XEN) HVM7: uesp CFB4 uss 0
>> (XEN) HVM7: ves D00 vds D00 vfs 0 vgs 0
>> (XEN) HVM7: cr0 50032 cr2 0 cr3 0 cr4 651
>> (XEN) HVM7:
>> (XEN) HVM7: Trap (0x6) while in real mode
>> (XEN) HVM7: eax D00 ecx 0 edx 71F ebx 89
>> (XEN) HVM7: esp D75E4 ebp D7630 esi D7620 edi D00
>> (XEN) HVM7: trapno 6 errno 0
>> (XEN) HVM7: eip D0800 cs 10 eflags 13046
>> (XEN) HVM7: uesp 71F uss D76D4
>> (XEN) HVM7: ves D7610 vds D3AB9 vfs D762C vgs D7644
>> (XEN) HVM7: cr0 50032 cr2 0 cr3 0 cr4 651
>> (XEN) HVM7:
>> (XEN) HVM7: 0xd0800 is 0xFFFF
>> (XEN) HVM7: 0xd0804 is 0x7D8B
>> (XEN) HVM7: Halt called from %eip 0xD037C
>>
>>
>> On 8/7/07, Keir Fraser <keir@xxxxxxxxxxxxx> wrote:
>>> How about trying:
>>> printf("Before fetch8\n");
>>> dump_regs(regs);
>>> opc = fetch8(regs);
>>> printf("After fetch8\n");
>>> switch (opc) { ...
>>>
>>> This will let you see what eip is being fetched from, and also confirm that
>>> the crash happens within fetch8().
>>>
>>> You could also try adding more printf()s inside fetch8() and address() to
>>> find out which specific bit of fetch8() is crashing (if that indeed the
>>> function that is crashing).
>>>
>>> -- Keir
>>>
>>> On 7/8/07 11:30, "Brady Chen" <chenchp@xxxxxxxxx> wrote:
>>>
>>>> Hi, Keir,
>>>> I made the change as you said:
>>>> change diff is:
>>>> [root@localhost firmware]# hg diff vmxassist/vm86.c
>>>> diff -r 6f18f5bdeea3 tools/firmware/vmxassist/vm86.c
>>>> --- a/tools/firmware/vmxassist/vm86.c Mon Aug 06 15:33:42 2007 +0100
>>>> +++ b/tools/firmware/vmxassist/vm86.c Tue Aug 07 18:26:12 2007 +0800
>>>> @@ -40,7 +40,7 @@ static struct regs saved_rm_regs;
>>>> static struct regs saved_rm_regs;
>>>>
>>>> #ifdef DEBUG
>>>> -int traceset = 0;
>>>> +int traceset = ~0;
>>>>
>>>> char *states[] = {
>>>> "<VM86_REAL>",
>>>> @@ -620,6 +620,7 @@ movr(struct regs *regs, unsigned prefix,
>>>> TRACE((regs, regs->eip - eip,
>>>> "movw %%%s, *0x%x", rnames[r], addr));
>>>> write16(addr, MASK16(val));
>>>> + printf("after write16 of movw\n");
>>>> }
>>>> return 1;
>>>>
>>>> @@ -1305,6 +1306,7 @@ opcode(struct regs *regs)
>>>> unsigned eip = regs->eip;
>>>> unsigned opc, modrm, disp;
>>>> unsigned prefix = 0;
>>>> + printf("top of opcode\n");
>>>>
>>>> if (mode == VM86_PROTECTED_TO_REAL &&
>>>> oldctx.cs_arbytes.fields.default_ops_size) {
>>>> @@ -1712,6 +1714,8 @@ trap(int trapno, int errno, struct regs
>>>> if (trapno == 14)
>>>> printf("Page fault address 0x%x\n", get_cr2());
>>>> dump_regs(regs);
>>>> + printf("0xd0800 is 0x%0x\n", *((unsigned short*)0xd0800));
>>>> + printf("0xd0804 is 0x%0x\n", *((unsigned short*)0xd0804));
>>>> halt();
>>>> }
>>>> }
>>>>
>>>>
>>>> here is the output:
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: 0x0000D71F: 0xD00:0x071F (0) data32
>>>> (XEN) HVM6: 0x0000D71F: 0xD00:0x071F (0) opc 0x83
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: 0x0000D71B: 0xD00:0x071B (0) %es:
>>>> (XEN) HVM6: 0x0000D71B: 0xD00:0x071B (0) addr32
>>>> (XEN) HVM6: 0x0000D71D: 0xD00:0x071D (0) movw %ax, *0xD07FE
>>>> (XEN) HVM6: after write16 of movw
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: Trap (0x6) while in real mode
>>>> (XEN) HVM6: eax D00 ecx 0 edx 71F ebx 71E
>>>> (XEN) HVM6: esp D7554 ebp D75A0 esi D7590 edi D00
>>>> (XEN) HVM6: trapno 6 errno 0
>>>> (XEN) HVM6: eip D0800 cs 10 eflags 13046
>>>> (XEN) HVM6: uesp D4C29 uss 2
>>>> (XEN) HVM6: ves D4C18 vds D4D9C vfs D07FE vgs D75B4
>>>> (XEN) HVM6: cr0 50032 cr2 0 cr3 0 cr4 651
>>>> (XEN) HVM6:
>>>> (XEN) HVM6: 0xd0800 is 0xFFFF
>>>> (XEN) HVM6: 0xd0804 is 0x7D8B
>>>> (XEN) HVM6: Halt called from %eip 0xD037C
>>>>
>>>> objdump:
>>>> d07ef: e9 2f ff ff ff jmp d0723 <address+0x23>
>>>> d07f4: 8b 55 08 mov 0x8(%ebp),%edx
>>>> d07f7: 89 f8 mov %edi,%eax
>>>> d07f9: 8b 5d f4 mov 0xfffffff4(%ebp),%ebx
>>>> d07fc: 8b 75 f8 mov 0xfffffff8(%ebp),%esi
>>>> d07ff: 25 ff ff 00 00 and $0xffff,%eax
>>>> d0804: 8b 7d fc mov 0xfffffffc(%ebp),%edi
>>>> d0807: 89 ec mov %ebp,%esp
>>>> d0809: c1 e0 04 shl $0x4,%eax
>>>> d080c: 01 d0 add %edx,%eax
>>>> d080e: 5d pop %ebp
>>>>
>>>> seems the memory is correct, it's crashed in opcode()
>>>> and i think it's fetch8(regs) which crash the system. I tried
>>>> fetch8(regs) in trap(), but it cause more traps, and let the hvm guest
>>>> be reset.
>>>>
>>>> On 8/7/07, Keir Fraser <keir@xxxxxxxxxxxxx> wrote:
>>>>> On 7/8/07 10:29, "Keir Fraser" <keir@xxxxxxxxxxxxx> wrote:
>>>>>
>>>>>> What would be useful is to try to add tracing to see how far vmxassist
>>>>>> gets
>>>>>> after its last line of tracing before the trap occurs. That last line is
>>>>>> currently from vm86.c, line 620. You might try adding extra printf()
>>>>>> statements imemdiately after the write16() on line 622, and also at the
>>>>>> top
>>>>>> of the opcode() function. We need to find out at what point vmxassist is
>>>>>> jumping to this bogus address d0800.
>>>>>
>>>>> Oh, another possibility is that vmxassist has been corrupted in memory.
>>>>> This
>>>>> is particularly likely because, according to the objdump, the
>>>>> 'instruction'
>>>>> that starts at d0800 is actually valid (it'd be an ADD of some sort).
>>>>>
>>>>> So, within trap() you might want to read say 16 bytes starting at 0xd0800
>>>>> and printf() them. So we can see if they match what objdump says should be
>>>>> there.
>>>>>
>>>>> -- Keir
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>>> http://lists.xensource.com/xen-devel
>>>
>>>
>>
>
> _______________________________________________
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