x86, pkeys: create an x86 arch_calc_vm_prot_bits() for VMA flags

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

calc_vm_prot_bits() takes PROT_{READ,WRITE,EXECUTE} bits and
turns them in to the vma->vm_flags/VM_* bits.  We need to do a
similar thing for protection keys.

We take a protection key (4 bits) and encode it in to the 4
VM_PKEY_* bits.

Note: this code is not new.  It was simply a part of the
mprotect_pkey() patch in the past.  I broke it out for use
in the execute-only support.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
1 file changed