On Fri, 28 Feb 2014 12:11:11 +0100
Peter Zijlstra <pet...@infradead.org> wrote:
> On Thu, Feb 27, 2014 at 09:57:26PM -0500, Steven Rostedt wrote:
> > @@ -512,8 +508,21 @@ static inline void nmi_nesting_postprocess(void)
> > dotraplinkage notrace __kprobes void
> > do_nmi(struct pt_regs *regs, long error_code)
> > {
> > + unsigned long cr2;
> > +
> > nmi_nesting_preprocess(regs);
> >
> > + /*
> > + * Save off the CR2 register. If we take a page fault in the NMI then
> > + * it could corrupt the CR2 value. If the NMI preempts a page fault
> > + * handler before it was able to read the CR2 register, and then the
> > + * NMI itself takes a page fault, the page fault that was preempted
> > + * will read the information from the NMI page fault and not the
> > + * origin fault. Save it off and restore it if it changes.
>
> > + * Use the r12 callee-saved register.
>
> You might want to make that line go away :-)
>
Gah! I noticed that before sending and deleted the line, recreated the
patch and sent that out. The one step I forgot to do was to save the
file after deleting it :-p
-- Steve
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