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Subject[PATCH 8/9] x86, pkeys, selftests: add allow faults on unknown keys
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From: Dave Hansen <dave.hansen@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.hansen@linux.intel.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@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.
_
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