lkml.org 
[lkml]   [2017]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
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
> <dave.hansen@linux.intel.com> wrote:
> >
> > From: Dave Hansen <dave.hansen@linux.intel.com>
> >
> > 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
do_nmi().

> 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.

Thanks,

tglx

\
 
 \ /
  Last update: 2017-11-20 21:55    [W:0.083 / U:3.696 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site