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 0ドルxffff,%eax
 d0804: 8b 7d fc mov 0xfffffffc(%ebp),%edi
 d0807: 89 ec mov %ebp,%esp
 d0809: c1 e0 04 shl 0ドルx4,%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