Re: Memory protection keys: Signal handlers crash if pkey0 is write-disabled

[Dave Hansen]

On 9/7/23 14:22, Robert Kueffner wrote:
> Is there some way to make this work, or is it generally not possible
> to successfully handle exceptions if WD0=true?

It's theoretically possible, but it's in a grey area.  The kernel can't
easily try to respect PKRU *and* override it for things like decoding
userspace instructions.

PKRU should get reset to a value that permits reads and writes to pkey-0
before the signal frame is created.  But you're obviously tripping over
it anyway.

I assume that *something* is trying to access pkey-0-protected memory.
Any idea what that is?  Which entity is doing that access and what are
they accessing?  The page fault tracepoints might come in handy.