[PATCH 8/9] x86, pkeys, selftests: add allow faults on unknown keys

[Dave Hansen]

From: Dave Hansen <dave.han...@linux.intel.com>

The exec-only pkey is allocated inside the kernel and userspace
is not told what it is.  So, allow PK faults to occur that have
an unknown key.

Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
Cc: Ram Pai <linux...@us.ibm.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Dave Hansen <dave.han...@intel.com>
Cc: Michael Ellermen <m...@ellerman.id.au>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Shuah Khan <sh...@kernel.org>
---

 b/tools/testing/selftests/x86/protection_keys.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff -puN 
tools/testing/selftests/x86/protection_keys.c~pkeys-selftests-unknown-exec-only-key
 tools/testing/selftests/x86/protection_keys.c
--- 
a/tools/testing/selftests/x86/protection_keys.c~pkeys-selftests-unknown-exec-only-key
       2018-03-26 10:22:37.549170187 -0700
+++ b/tools/testing/selftests/x86/protection_keys.c     2018-03-26 
10:22:37.553170187 -0700
@@ -922,13 +922,21 @@ void *malloc_pkey(long size, int prot, u
 }
 
 int last_pkru_faults;
+#define UNKNOWN_PKEY -2
 void expected_pk_fault(int pkey)
 {
        dprintf2("%s(): last_pkru_faults: %d pkru_faults: %d\n",
                        __func__, last_pkru_faults, pkru_faults);
        dprintf2("%s(%d): last_si_pkey: %d\n", __func__, pkey, last_si_pkey);
        pkey_assert(last_pkru_faults + 1 == pkru_faults);
-       pkey_assert(last_si_pkey == pkey);
+
+       /*
+       * For exec-only memory, we do not know the pkey in
+       * advance, so skip this check.
+       */
+       if (pkey != UNKNOWN_PKEY)
+               pkey_assert(last_si_pkey == pkey);
+
        /*
         * The signal handler shold have cleared out PKRU to let the
         * test program continue.  We now have to restore it.
_