Re: [Xen-devel] [PATCH] xen/x86: Introduce early_invalid_op() handler.

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 09/09/13 15:37, Keir Fraser wrote:
> On 09/09/2013 07:30, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>
>>>>> On 09.09.13 at 16:17, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>> +void __init  __attribute__((noreturn))
>>> +do_early_invalid_op(struct cpu_user_regs *regs)
>>> +{
>>> +    if ( *(u16 *)regs->eip == 0x0b0f )
>> Without even a range check on regs->eip? I don't think we want to
>> needlessly risk #PF or #GP here...
>>
>>> +        printk("Early ud2 at %p - BUG/WARN/ASSERT perhaps?\n",
>>> _p(regs->eip));
>>> +    else
>>> +        printk("Unidentified early #UD at %p\n", _p(regs->eip));
>>> +
>> You probably also meant to at least print the same raw stack
>> dump that do_early_page_fault() produces?
> I suggest less cleverness in this printk and indeed dump regs and error
> code. More useful, potentially. Also then the handler will not be
> UD-specific and could be called for all early exceptions (except those with
> a more specific handler such as #PG).
>
> All that would be needed in asm is a per-exception push/mov and jmp to
> common asm which does the SAVE_ALL stuff and jmp to C.
>
>  -- Keir

Ok - I will see about implementing this.

~Andrew

>
>> Jan
>>
>>> +    for ( ; ; )
>>> +        halt();
>>> +}
>>
>
>
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