Re: [PATCH v4 1/2] x86/unwind: add ORC unwinder

[Juergen Gross]

On 09/08/17 11:16, Peter Zijlstra wrote:
> On Wed, Aug 09, 2017 at 10:49:43AM +0200, Juergen Gross wrote:
>>> ALTERNATIVE "pushfq; popq %rax", "callq *pv_irq_ops.save_fl",
>>> X86_FEATURE_GODDAMN_PV_IRQ_OPS
>>
>> You are aware that at least some of the Xen irq pvops functionality is
>> patched inline? Your modification would slow down pv guests quite a
>> bit, I guess.
> 
> Where does that live? I know of the inline patching for native, but
> didn't know the guests did any of that too.

See arch/x86/xen/enlighten_pv.c xen_patch().


Juergen