powerpc/mm: Remove the dependency on pte bit position in asm code

We should not expect pte bit position in asm code. Simply
by moving part of that to C
Acked-by: NScott Wood <scottwood@freescale.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/exceptions-64s.S

@@ -1556,29 +1556,19 @@ do_hash_page:
 	lwz	r0,TI_PREEMPT(r11)	/* If we're in an "NMI" */
 	andis.	r0,r0,NMI_MASK@h	/* (i.e. an irq when soft-disabled) */
 	bne	77f			/* then don't call hash_page now */
-	/*
-	 * We need to set the _PAGE_USER bit if MSR_PR is set or if we are
-	 * accessing a userspace segment (even from the kernel). We assume
-	 * kernel addresses always have the high bit set.
-	 */
-	rlwinm	r4,r4,32-25+9,31-9,31-9	/* DSISR_STORE -> _PAGE_RW */
-	rotldi	r0,r3,15		/* Move high bit into MSR_PR posn */
-	orc	r0,r12,r0		/* MSR_PR | ~high_bit */
-	rlwimi	r4,r0,32-13,30,30	/* becomes _PAGE_USER access bit */
-	ori	r4,r4,1			/* add _PAGE_PRESENT */
-	rlwimi	r4,r5,22+2,31-2,31-2	/* Set _PAGE_EXEC if trap is 0x400 */
 
 	/*
 	 * r3 contains the faulting address
-	 * r4 contains the required access permissions
+	 * r4 msr
 	 * r5 contains the trap number
 	 * r6 contains dsisr
 	 *
 	 * at return r3 = 0 for success, 1 for page fault, negative for error
 	 */
+        mr 	r4,r12
 	ld      r6,_DSISR(r1)
-	bl	hash_page		/* build HPTE if possible */
-	cmpdi	r3,0			/* see if hash_page succeeded */
+	bl	__hash_page		/* build HPTE if possible */
+        cmpdi	r3,0			/* see if __hash_page succeeded */
 
 	/* Success */
 	beq	fast_exc_return_irq	/* Return from exception on success */

arch/powerpc/mm/hash_utils_64.c

@@ -1206,6 +1206,35 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
 }
 EXPORT_SYMBOL_GPL(hash_page);
 
+int __hash_page(unsigned long ea, unsigned long msr, unsigned long trap,
+		unsigned long dsisr)
+{
+	unsigned long access = _PAGE_PRESENT;
+	unsigned long flags = 0;
+	struct mm_struct *mm = current->mm;
+
+	if (REGION_ID(ea) == VMALLOC_REGION_ID)
+		mm = &init_mm;
+
+	if (dsisr & DSISR_NOHPTE)
+		flags |= HPTE_NOHPTE_UPDATE;
+
+	if (dsisr & DSISR_ISSTORE)
+		access |= _PAGE_RW;
+	/*
+	 * We need to set the _PAGE_USER bit if MSR_PR is set or if we are
+	 * accessing a userspace segment (even from the kernel). We assume
+	 * kernel addresses always have the high bit set.
+	 */
+	if ((msr & MSR_PR) || (REGION_ID(ea) == USER_REGION_ID))
+		access |= _PAGE_USER;
+
+	if (trap == 0x400)
+		access |= _PAGE_EXEC;
+
+	return hash_page_mm(mm, ea, access, trap, flags);
+}
+
 void hash_preload(struct mm_struct *mm, unsigned long ea,
 		  unsigned long access, unsigned long trap)
 {