selftests/powerpc: Fix exit status of pkey tests

Since main() does not return a value explicitly, the
return values from FAIL_IF() conditions are ignored
and the tests can still pass irrespective of failures.
This makes sure that we always explicitly return the
correct test exit status.

Fixes: 1addb6444791 ("selftests/powerpc: Add test for execute-disabled pkeys")
Fixes: c27f2fd1705a ("selftests/powerpc: Add test for pkey siginfo verification")
Reported-by: Eirik Fuller <efuller@redhat.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210118093145.10134-1-sandipan@linux.ibm.com

selftests/powerpc: Add test for pkey siginfo verification

Commit c46241a370a61 ("powerpc/pkeys: Check vma before
returning key fault error to the user") fixes a bug which
causes the kernel to set the wrong pkey in siginfo when a
pkey fault occurs after two competing threads that have
allocated different pkeys, one fully permissive and the
other restrictive, attempt to protect a common page at the
same time. This adds a test to detect the bug.

Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ce40b6ee270bda52e8f4088578ed2faf7d1d509a.1595821792.git.sandipan@linux.ibm.com