nios2: use generic strncpy_from_user() and strnlen_user()

This change enables the generic strncpy_from_user() and strnlen_user()
Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>

arch/nios2/Kconfig

@@ -6,6 +6,8 @@ config NIOS2
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
+	select GENERIC_STRNCPY_FROM_USER
+	select GENERIC_STRNLEN_USER
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_KGDB
 	select IRQ_DOMAIN

arch/nios2/include/asm/uaccess.h

@@ -42,6 +42,8 @@
 
 # define __EX_TABLE_SECTION	".section __ex_table,\"a\"\n"
 
+#define user_addr_max() (uaccess_kernel() ? ~0UL : TASK_SIZE)
+
 /*
  * Zero Userspace
  */
@@ -82,7 +84,8 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n);
 
 extern long strncpy_from_user(char *__to, const char __user *__from,
 			      long __len);
-extern long strnlen_user(const char __user *s, long n);
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *s, long n);
 
 /* Optimized macros */
 #define __get_user_asm(val, insn, addr, err)				\

arch/nios2/mm/uaccess.c

@@ -128,36 +128,3 @@ asm(
 	".word 12b,13b\n"
 	".previous\n");
 EXPORT_SYMBOL(raw_copy_to_user);
-
-long strncpy_from_user(char *__to, const char __user *__from, long __len)
-{
-	int l = strnlen_user(__from, __len);
-	int is_zt = 1;
-
-	if (l > __len) {
-		is_zt = 0;
-		l = __len;
-	}
-
-	if (l == 0 || copy_from_user(__to, __from, l))
-		return -EFAULT;
-
-	if (is_zt)
-		l--;
-	return l;
-}
-
-long strnlen_user(const char __user *s, long n)
-{
-	long i;
-
-	for (i = 0; i < n; i++) {
-		char c;
-
-		if (get_user(c, s + i) == -EFAULT)
-			return 0;
-		if (c == 0)
-			return i + 1;
-	}
-	return n + 1;
-}