Re: [patch V181 49/54] x86/dumpstack: Indicate in Oops whether pti is configured and enabled

From: Jiri Kosina
Date: Wed Dec 20 2017 - 17:03:56 EST

On Wed, 20 Dec 2017, Thomas Gleixner wrote:

> From: Vlastimil Babka <vbabka@xxxxxxx>
> CONFIG_PAGE_TABLE_ISOLATION is relatively new and intrusive feature that may
> still have some corner cases which could take some time to manifest and be
> fixed. It would be useful to have Oops messages indicate whether it was
> enabled for building the kernel, and whether it was disabled during boot.
> Example of fully enabled:
> Oops: 0001 [#1] SMP PTI
> Example of enabled during build, but disabled during boot:
> Oops: 0001 [#1] SMP NOPTI
> We can decide to remove this after the feature has been tested in the field
> long enough.
> [ tglx: Made it use boot_cpu_has() as requested by Borislav ]
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Reviewed-by: Eduardo Valentin <eduval@xxxxxxxxxx>
> Acked-by: Dave Hansen <dave.hansen@xxxxxxxxx>


Acked-by: Jiri Kosina <jkosina@xxxxxxx>

I've had a much more stupid variant of this when fuzzing pti/nopti kernels
(distro backports, of course), and it was really helpful when diving into
the crashes.


Jiri Kosina