Re: [RFC PATCH 1/7] static_call/x86: Add __static_call_returnl0()

[Frederic Weisbecker]

On Tue, Nov 10, 2020 at 11:13:07AM +0100, Peter Zijlstra wrote:
> On Tue, Nov 10, 2020 at 10:55:15AM +0100, Peter Zijlstra wrote:
> > On Tue, Nov 10, 2020 at 01:56:03AM +0100, Frederic Weisbecker wrote:
> > 
> > > [fweisbec: s/disp16/data16, integrate into text_get_insn(), elaborate
> > >  comment on the resulting insn, emulate on int3 trap, provide validation,
> > >  uninline __static_call_return0() for HAVE_STATIC_CALL]
> 
> > Why did you add full emulation of this? The patch I send to you used the
> > text_poke_bp(.emulate) argument to have it emulate an actual call to the
> > out-of-line version of that function.
> > 
> > That should work fine and is a lot less code.
> 
> For reference; the below is what I send you. Actually doing the
> __static_call_return0() call while we poke the magic XOR instruction is
> much simpler.

Ok I'll get back to that. I'll just tweak a bit static_call_validate()
so that it is aware of that instruction.

Thanks.