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SubjectRe: [PATCH 17/30] x86, kaiser: map debug IDT tables
On Mon, 20 Nov 2017, Andy Lutomirski wrote:

> On Fri, Nov 10, 2017 at 11:31 AM, Dave Hansen
> <> wrote:
> >
> > From: Dave Hansen <>
> >
> > The IDT is another structure which the CPU references via a
> > virtual address. It also obviously needs these to handle an
> > interrupt in userspace, so these need to be mapped into the user
> > copy of the page tables.
> Why would the debug IDT ever be used in user mode? IIRC it's a total
> turd related to avoiding crap nesting inside NMI. Or am I wrong?

No. It's called from the TRACE_IRQS macros in the ASM entry code and from

> If it *is* used in user mode, then we have a bug and it should be in
> the IDT to avoid address leaks just like the normal IDT.

It's not so this can go away. Good catch.



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