[Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out

[Steven Rostedt <rostedt@xxxxxxxxxxx>]

On Thu, 2011-10-06 at 16:33 -0400, Jason Baron wrote:

> > Then have the record_jumplabel.c (or whatever it's called) find all the
> > jmps at run time, and convert them into the appropriate nop.
> > 
> 
> I'd prefer to do this at build-time as hpa said. We don't want there to
> be some race b/w patching in the no-ops and taking an incorrect branch.

Yep, this record_jumplabel.c would execute at build time. Just like the
record_mcount.c does.

> 
> > Then at runtime patching, the jumplabel code could figure out what size
> > jump it needs to replace it.

The runtime patching is when we can figure out what size the compiler
used. That wont change. It should be pretty trivial to do. I can't see
any races here.

-- Steve





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