Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)

[Mathieu Desnoyers]

* H. Peter Anvin (hpa@xxxxxxxxx) wrote:
> Pavel Machek wrote:
>>> There is also the page fault case. I think putting this test in
>>> ret_from_exception would be both safe (it is executed for any
>>> exception return) and fast (exceptions are rare).
>> Eh? I thought that page fault is one of the hottest paths in kernel
>> (along with syscall and packet receive/send)...
>> 								Pavel
>

On x86_64, we can pinpoint only the page faults returning to the kernel,
which are rare and only caused by vmalloc accesses. Ideally we could do
the same on x86_32.

> Yeah, and the concept of handling page faults inside an NMI handler is pure 
> fantasy.
>
> 	-hpa
>

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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