Re: [Xen-devel] [PATCH 2/5] xen/x86-64: clean up warnings aboutIST-usingtraps

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> Jeremy Fitzhardinge <jeremy@xxxxxxxx> 08.05.09 17:23 >>>
>Jan Beulich wrote:
>>> else if (addr == (unsigned long)int3)
>>>             addr = (unsigned long)xen_int3;
>>> -   else
>>> -           WARN_ON(val->ist != 0);
>>> +   else if (addr == (unsigned long)double_fault ||
>>> +            addr == (unsigned long)stack_segment) {
>>>     
>>
>> I don't think you want to exclude handling stack faults: Ordinary memory
>> references using rsp or rbp as the base register will cause these instead
>> of general protection faults when the resulting effective address is non-
>> canonical.
>>   
>
>So even usermode memory accesses?  Ew.

Yes, just try it out - you'll observe them generate SIGBUS instead of SIGSEGV.

Jan


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