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

[Dave Hansen]

From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

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.hansen@xxxxxxxxxxxxxxx>
Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Michael Ellermen <mpe@xxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
---

 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	2018-03-21 15:47:51.985198917 -0700
+++ b/tools/testing/selftests/x86/protection_keys.c	2018-03-21 15:47:51.988198917 -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.
_