Re: [PATCH] x86_64: make traps on 'iret' be debuggable in user space

From: Chuck Ebbert
Date: Thu Feb 07 2008 - 18:28:55 EST


On 02/07/2008 03:30 PM, Roland McGrath wrote:
>> Did you test without CONFIG_PARAVIRT, and CONFIG_PARAVIRT booted both with and
>> without the "noreplace-paravirt" parameter?
>
> I did not test CONFIG_PARAVIRT at all. I just fixed what its introduction
> had done to break generic x86-64.
>
>

It looks you may have broken paravirt (if even that case worked) because
the iret is actually at the iret_label you removed (after the instruction
is patched.) And most likely neither version worked with "noreplace-paravirt',
because then the iret instruction is out-of-line and the INTERRUPT_RETURN
jumps to it.


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