powerpc/mm: PTE_ATOMIC_UPDATES is only for 40x

Only 40x still uses PTE_ATOMIC_UPDATES.
40x cannot not select CONFIG_PTE64_BIT.

Drop handling of PTE_ATOMIC_UPDATES:
- In nohash/64
- In nohash/32 for CONFIG_PTE_64BIT

Keep PTE_ATOMIC_UPDATES only for nohash/32 for !CONFIG_PTE_64BIT

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d6f8e1f46583f1842de24581a68b0496feb15516.1589866984.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -262,25 +262,8 @@ static inline unsigned long long pte_update(pte_t *p,
 					    unsigned long clr,
 					    unsigned long set)
 {
-#ifdef PTE_ATOMIC_UPDATES
-	unsigned long long old;
-	unsigned long tmp;
-
-	__asm__ __volatile__("\
-1:	lwarx	%L0,0,%4\n\
-	lwzx	%0,0,%3\n\
-	andc	%1,%L0,%5\n\
-	or	%1,%1,%6\n"
-	PPC405_ERR77(0,%3)
-"	stwcx.	%1,0,%4\n\
-	bne-	1b"
-	: "=&r" (old), "=&r" (tmp), "=m" (*p)
-	: "r" (p), "r" ((unsigned long)(p) + 4), "r" (clr), "r" (set), "m" (*p)
-	: "cc" );
-#else /* PTE_ATOMIC_UPDATES */
 	unsigned long long old = pte_val(*p);
 	*p = __pte((old & ~(unsigned long long)clr) | set);
-#endif /* !PTE_ATOMIC_UPDATES */
 
 #ifdef CONFIG_44x
 	if ((old & _PAGE_USER) && (old & _PAGE_EXEC))

arch/powerpc/include/asm/nohash/64/pgtable.h

@@ -211,22 +211,9 @@ static inline unsigned long pte_update(struct mm_struct *mm,
 				       unsigned long set,
 				       int huge)
 {
-#ifdef PTE_ATOMIC_UPDATES
-	unsigned long old, tmp;
-
-	__asm__ __volatile__(
-	"1:	ldarx	%0,0,%3		# pte_update\n\
-	andc	%1,%0,%4 \n\
-	or	%1,%1,%6\n\
-	stdcx.	%1,0,%3 \n\
-	bne-	1b"
-	: "=&r" (old), "=&r" (tmp), "=m" (*ptep)
-	: "r" (ptep), "r" (clr), "m" (*ptep), "r" (set)
-	: "cc" );
-#else
 	unsigned long old = pte_val(*ptep);
 	*ptep = __pte((old & ~clr) | set);
-#endif
+
 	/* huge pages use the old page table lock */
 	if (!huge)
 		assert_pte_locked(mm, addr);
@@ -310,21 +297,8 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 	unsigned long bits = pte_val(entry) &
 		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 
-#ifdef PTE_ATOMIC_UPDATES
-	unsigned long old, tmp;
-
-	__asm__ __volatile__(
-	"1:	ldarx	%0,0,%4\n\
-		or	%0,%3,%0\n\
-		stdcx.	%0,0,%4\n\
-		bne-	1b"
-	:"=&r" (old), "=&r" (tmp), "=m" (*ptep)
-	:"r" (bits), "r" (ptep), "m" (*ptep)
-	:"cc");
-#else
 	unsigned long old = pte_val(*ptep);
 	*ptep = __pte(old | bits);
-#endif
 
 	flush_tlb_page(vma, address);
 }