On 06/13/2018 05:45 PM, Ram Pai wrote:

Generally the signal handler restores the state of the pkey register
before returning. However there are times when the read/write operation
can legitamely fail without invoking the signal handler.  Eg: A
sys_read() operaton to a write-protected page should be disallowed.  In
such a case the state of the pkey register is not restored to its
original state.  The test case is responsible for restoring the key
register state to its original value.

Seems fragile.  Can't we just do this in common code?  We could just
loop through and restore the default permissions.  That seems much more
resistant to a bad test case.