Messages in this thread |  | | | Date | Thu, 28 Feb 2008 16:04:44 +0100 | | From | "Klaus S. Madsen" <> | | Subject | Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending |
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On Thu, Feb 28, 2008 at 10:40:00 +0100, Ingo Molnar wrote: > > * Klaus S. Madsen <ksm@hjernemadsen.org> wrote: > > > > > 524 int r; > > > > 525 #ifdef __PIC__ > > > > 526 asm volatile ( > > > > 527 "pushl %%ebx\n\t" > > > > 528 "movl %2, %%ebx\n\t" > > > > 529 "int $0x80\n\t" > > > > 530 "popl %%ebx" > > > > (gdb) bt > > > > #0 0xb7facf4a in run_vm86 () at lrmi.c:526 > > > > #1 0xb7fad61b in LRMI_int (i=16, r=0xbffca670) at lrmi.c:844 > > > > #2 0x0804acfc in do_vbe_service (AX=20227, BX=0, regs=0xbffca670) > > > > at vbetool/vbetool.c:158 > > > > #3 0x0804af7e in __get_mode () at vbetool/vbetool.c:453 > > > > #4 0x0804a30f in s2ram_hacks () at s2ram-x86.c:268 > > > > #5 0x0804954f in main (argc=1, argv=0x0) at s2ram-main.c:92
[snip]
> > > thanks for tracking this down. It would be nice to figure out why this > > > change made a difference. Perhaps VM86 mode has some restrictions in > > > what type of pagetables it can operate in - and the CPU just refuses to > > > properly emulate those 16-bit instructions? (this would be very weird). > > > We are trying to execute 16-bit BIOS code here, right? > > > > > > which instruction is the segfault coming from - the int $0x80? So in > > > vm86 mode we generated a #GPF which shows up as a SIGSEGV?
The segfault was at address 0xb7f59f4a, and the disassembly of the run_vm86 function is:
0xb7f59f20 <run_vm86+0>: push %ebp 0xb7f59f21 <run_vm86+1>: mov %esp,%ebp 0xb7f59f23 <run_vm86+3>: push %edi 0xb7f59f24 <run_vm86+4>: push %esi 0xb7f59f25 <run_vm86+5>: push %ebx 0xb7f59f26 <run_vm86+6>: call 0xb7f59697 <__i686.get_pc_thunk.bx> 0xb7f59f2b <run_vm86+11>: add $0x18b5,%ebx 0xb7f59f31 <run_vm86+17>: sub $0x3c,%esp 0xb7f59f34 <run_vm86+20>: lea 0x48c(%ebx),%eax 0xb7f59f3a <run_vm86+26>: mov %eax,0xffffffc0(%ebp) 0xb7f59f3d <run_vm86+29>: mov $0x71,%eax 0xb7f59f42 <run_vm86+34>: mov 0xffffffc0(%ebp),%ecx 0xb7f59f45 <run_vm86+37>: push %ebx 0xb7f59f46 <run_vm86+38>: mov %ecx,%ebx 0xb7f59f48 <run_vm86+40>: int $0x80 0xb7f59f4a <run_vm86+42>: pop %ebx 0xb7f59f4b <run_vm86+43>: mov %eax,%edx 0xb7f59f4d <run_vm86+45>: and $0xff,%eax 0xb7f59f52 <run_vm86+50>: cmp $0x2,%eax 0xb7f59f55 <run_vm86+53>: je 0xb7f5a0b5 <run_vm86+405> 0xb7f59f5b <run_vm86+59>: sub $0x1,%eax 0xb7f59f5e <run_vm86+62>: jne 0xb7f5a28a <run_vm86+874> Hope this helps.
-- Kind regards Klaus S. Madsen
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