Re: [PATCH 12/31] x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points

[Andy Lutomirski]

On Fri, Mar 2, 2018 at 9:10 AM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> On Thu, Mar 01, 2018 at 10:38:21AM -0800, Linus Torvalds wrote:
>> Note that debug traps can happen regardless of TF, Think kgdb etc.
>> Arguably kgdb users get what they deserve, but still.. I think root
>> can set kernel breakpoints too.
>
> But that seems to be broken right now at least wrt. to the espfix code
> where there is no handling for in the #DB handler. Can userspace really
> set arbitrary kernel breakpoints?
>

As far as I'm concerned, I don't try to support kernel debugger users
setting arbitrary breakpoints in the kernel entry text.