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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