[PATCH v12 16/22] selftests/vm: fix an assertion in test_pkey_alloc_exhaust()

[Ram Pai]

The maximum number of keys that can be allocated has to
take into consideration, that some keys are reserved by
the architecture for   specific   purpose. Hence cannot
be allocated.

Fix the assertion in test_pkey_alloc_exhaust()

cc: Dave Hansen <dave.hansen@xxxxxxxxx>
cc: Florian Weimer <fweimer@xxxxxxxxxx>
Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
---
 tools/testing/selftests/vm/pkey-helpers.h    |   14 ++++++++++++++
 tools/testing/selftests/vm/protection_keys.c |    9 ++++-----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/vm/pkey-helpers.h b/tools/testing/selftests/vm/pkey-helpers.h
index 88ef58f..67f9b0f 100644
--- a/tools/testing/selftests/vm/pkey-helpers.h
+++ b/tools/testing/selftests/vm/pkey-helpers.h
@@ -416,4 +416,18 @@ static inline int get_start_key(void)
 #endif
 }
 
+static inline int arch_reserved_keys(void)
+{
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+	return NR_RESERVED_PKEYS;
+#elif __powerpc64__ /* arch */
+	if (sysconf(_SC_PAGESIZE) == 4096)
+		return NR_RESERVED_PKEYS_4K;
+	else
+		return NR_RESERVED_PKEYS_64K;
+#else /* arch */
+	NOT SUPPORTED
+#endif /* arch */
+}
+
 #endif /* _PKEYS_HELPER_H */
diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index 58da5a0..aae6771 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1167,12 +1167,11 @@ void test_pkey_alloc_exhaust(int *ptr, u16 pkey)
 	pkey_assert(i < NR_PKEYS*2);
 
 	/*
-	 * There are 16 pkeys supported in hardware.  One is taken
-	 * up for the default (0) and another can be taken up by
-	 * an execute-only mapping.  Ensure that we can allocate
-	 * at least 14 (16-2).
+	 * There are NR_PKEYS pkeys supported in hardware. arch_reserved_keys()
+	 * are reserved. One   can   be   taken   up by an execute-only mapping.
+	 * Ensure that we can allocate at least the remaining.
 	 */
-	pkey_assert(i >= NR_PKEYS-2);
+	pkey_assert(i >= (NR_PKEYS-arch_reserved_keys()-1));
 
 	for (i = 0; i < nr_allocated_pkeys; i++) {
 		err = sys_pkey_free(allocated_pkeys[i]);
-- 
1.7.1