[PATCH v13 13/24] selftests/vm: pkey register should match shadow pkey

[Ram Pai]

On Wed, Jun 20, 2018 at 07:53:57AM -0700, Dave Hansen wrote:
> On 06/13/2018 05:45 PM, Ram Pai wrote:
> > +++ b/tools/testing/selftests/vm/protection_keys.c
> > @@ -916,10 +916,10 @@ void expected_pkey_fault(int pkey)
> >  		pkey_assert(last_si_pkey == pkey);
> >  
> >  	/*
> > -	 * The signal handler shold have cleared out PKEY register to let the
> > +	 * The signal handler should have cleared out pkey-register to let the
> >  	 * test program continue.  We now have to restore it.
> >  	 */
> > -	if (__read_pkey_reg() != 0)
> > +	if (__read_pkey_reg() != shadow_pkey_reg)
> >  		pkey_assert(0);
> >  
> >  	__write_pkey_reg(shadow_pkey_reg);
> 
> I think this is wrong on x86.
> 
> When we leave the signal handler, we zero out PKRU so that the faulting
> instruction can continue, that's why we have the check against zero.
> I'm actually kinda surprised this works.

The code is modified to zero out only the violated key in the signal
handler. Hence it works. Have verified it to work on x86 aswell.

RP