Re: [Xen-ia64-devel] VTi: break handling

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mardi 11 Avril 2006 13:41, Xu, Anthony a écrit :
> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>
> >[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tristan
> >Gingold
> >Sent: 2006?4?11? 19:04
> >To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: [Xen-ia64-devel] VTi: break handling
> >
> >Hi,
> >
> >in vmx_ivt.S:
> >
> >// 0x2c00 Entry 11 (size 64 bundles) Break instruction (33)
> >ENTRY(vmx_break_fault)
> >    VMX_DBG_FAULT(11)
> >     mov r31=pr
> >    mov r19=11
> >    mov r30=cr.iim
> >    movl r29=0x1100
> >    ;;
> >
> >>>    cmp.eq p6,p7=r30,r0
> >>>    (p6) br.sptk vmx_fault_11
> >
> >    ;;
> >    cmp.eq  p6,p7=r29,r30
> >    (p6) br.dptk.few vmx_hypercall_dispatch
> >    (p7) br.sptk.many vmx_dispatch_break_fault
> >    ;;
> >    VMX_FAULT(11);
> >END(vmx_break_fault)
> >
> >Is the '>>' section debug code ? I fear a bug here.
>
> It was used for debug.
> Break 0, its opcode is 0,
> Usually break 0 is not used by linux kernel and application.
> When break 0 is executed, it usually means some thing wrong.
Sure, but if an application does break 0, it locks up Xen!
Maybe we should add a check.

Tristan.



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