[PATCH 30/32] x86, pkeys: create an x86 arch_calc_vm_prot_bits() for VMA flags

[Dave Hansen]

From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
---

 b/arch/x86/include/uapi/asm/mman.h |    6 ++++++
 1 file changed, 6 insertions(+)

diff -puN arch/x86/include/uapi/asm/mman.h~pkeys-78-arch_calc_vm_prot_bits arch/x86/include/uapi/asm/mman.h
--- a/arch/x86/include/uapi/asm/mman.h~pkeys-78-arch_calc_vm_prot_bits	2015-12-14 10:42:52.450235349 -0800
+++ b/arch/x86/include/uapi/asm/mman.h	2015-12-14 10:42:52.453235484 -0800
@@ -20,6 +20,12 @@
 		((vm_flags) & VM_PKEY_BIT1 ? _PAGE_PKEY_BIT1 : 0) |	\
 		((vm_flags) & VM_PKEY_BIT2 ? _PAGE_PKEY_BIT2 : 0) |	\
 		((vm_flags) & VM_PKEY_BIT3 ? _PAGE_PKEY_BIT3 : 0))
+
+#define arch_calc_vm_prot_bits(prot, key) (		\
+		((key) & 0x1 ? VM_PKEY_BIT0 : 0) |      \
+		((key) & 0x2 ? VM_PKEY_BIT1 : 0) |      \
+		((key) & 0x4 ? VM_PKEY_BIT2 : 0) |      \
+		((key) & 0x8 ? VM_PKEY_BIT3 : 0))
 #endif
 
 #include <asm-generic/mman.h>
_
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