powerpc/book3s64/pkeys: Mark all the pkeys above max pkey as reserved

The hypervisor can return less than max allowed pkey (for ex: 31) instead
of 32. We should mark all the pkeys above max allowed as reserved so
that we avoid the allocation of the wrong pkey(for ex: key 31 in the above
case) by userspace.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200709032946.881753-13-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index e9fd0db..d84bf55 100644 (file)
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -189,9 +189,10 @@ static int pkey_initialize(void)
 
        /*
         * Prevent the usage of OS reserved keys. Update UAMOR
-        * for those keys.
+        * for those keys. Also mark the rest of the bits in the
+        * 32 bit mask as reserved.
         */
-       for (i = num_pkey; i < pkeys_total; i++) {
+       for (i = num_pkey; i < 32 ; i++) {
                reserved_allocation_mask |= (0x1 << i);
                default_uamor &= ~(0x3ul << pkeyshift(i));
        }