powerpc/futex: Use masked user access

Commit 861574d ("powerpc/uaccess: Implement masked user access")
provides optimised user access by avoiding the cost of access_ok().

Use masked user access in arch_futex_atomic_op_inuser()

Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/e29f6a5c14e5938df68d94bfac6b2f762fb922aa.1773136636.git.chleroy@kernel.org

Author: Christophe Leroy (CS GROUP)

arch/powerpc/include/asm/futex.h

@@ -33,8 +33,7 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
-	if (!user_access_begin(uaddr, sizeof(u32)))
-		return -EFAULT;
+	uaddr = masked_user_access_begin(uaddr);
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -69,8 +68,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 	int ret = 0;
 	u32 prev;
 
-	if (!user_access_begin(uaddr, sizeof(u32)))
-		return -EFAULT;
+	uaddr = masked_user_access_begin(uaddr);
 
         __asm__ __volatile__ (
         PPC_ATOMIC_ENTRY_BARRIER