powerpc: ability to associate pkey to a vma

arch-independent code expects the arch to  map
a  pkey  into the vma's protection bit setting.
The patch provides that ability.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/mman.h

@@ -13,6 +13,7 @@
 
 #include <asm/cputable.h>
 #include <linux/mm.h>
+#include <linux/pkeys.h>
 #include <asm/cpu_has_feature.h>
 
 /*
@@ -22,7 +23,11 @@
 static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
 		unsigned long pkey)
 {
-	return (prot & PROT_SAO) ? VM_SAO : 0;
+#ifdef CONFIG_PPC_MEM_KEYS
+	return (((prot & PROT_SAO) ? VM_SAO : 0) | pkey_to_vmflag_bits(pkey));
+#else
+	return ((prot & PROT_SAO) ? VM_SAO : 0);
+#endif
 }
 #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
 

arch/powerpc/include/asm/pkeys.h

@@ -30,6 +30,17 @@ extern u32 initial_allocation_mask; /* bits set for reserved keys */
 #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
 			    VM_PKEY_BIT3 | VM_PKEY_BIT4)
 
+/* Override any generic PKEY permission defines */
+#define PKEY_DISABLE_EXECUTE   0x4
+#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS | \
+				PKEY_DISABLE_WRITE  | \
+				PKEY_DISABLE_EXECUTE)
+
+static inline u64 pkey_to_vmflag_bits(u16 pkey)
+{
+	return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS);
+}
+
 #define arch_max_pkey() pkeys_total
 
 #define pkey_alloc_mask(pkey) (0x1 << pkey)

arch/powerpc/mm/pkeys.c

@@ -34,6 +34,14 @@ int pkey_initialize(void)
 	BUILD_BUG_ON(PKEY_DISABLE_EXECUTE &
 		     (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
 
+	/*
+	 * pkey_to_vmflag_bits() assumes that the pkey bits are contiguous
+	 * in the vmaflag. Make sure that is really the case.
+	 */
+	BUILD_BUG_ON(__builtin_clzl(ARCH_VM_PKEY_FLAGS >> VM_PKEY_SHIFT) +
+		     __builtin_popcountl(ARCH_VM_PKEY_FLAGS >> VM_PKEY_SHIFT)
+				!= (sizeof(u64) * BITS_PER_BYTE));
+
 	/*
 	 * Disable the pkey system till everything is in place. A subsequent
 	 * patch will enable it.