microblaze: use generic strncpy/strnlen from_user

Remove the microblaze implemenation of strncpy/strnlen and instead use
the generic versions.  The microblaze version is fairly slow because it
always does byte accesses even for aligned data, and it lacks a checks
for user_addr_max().
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/microblaze/Kconfig

@@ -21,6 +21,8 @@ config MICROBLAZE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK
+	select GENERIC_STRNCPY_FROM_USER
+	select GENERIC_STRNLEN_USER
 	select HAVE_ARCH_HASH
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP

arch/microblaze/include/asm/uaccess.h

@@ -35,6 +35,7 @@
 
 # define get_fs()	(current_thread_info()->addr_limit)
 # define set_fs(val)	(current_thread_info()->addr_limit = (val))
+# define user_addr_max() get_fs().seg
 
 # define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)
 
@@ -296,28 +297,14 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 /*
  * Copy a null terminated string from userspace.
  */
-extern int __strncpy_user(char *to, const char __user *from, int len);
-
-static inline long
-strncpy_from_user(char *dst, const char __user *src, long count)
-{
-	if (!access_ok(src, 1))
-		return -EFAULT;
-	return __strncpy_user(dst, src, count);
-}
+__must_check long strncpy_from_user(char *dst, const char __user *src,
+				    long count);
 
 /*
  * Return the size of a string (including the ending 0)
  *
  * Return 0 on exception, a value greater than N if too long
  */
-extern int __strnlen_user(const char __user *sstr, int len);
-
-static inline long strnlen_user(const char __user *src, long n)
-{
-	if (!access_ok(src, 1))
-		return 0;
-	return __strnlen_user(src, n);
-}
+__must_check long strnlen_user(const char __user *sstr, long len);
 
 #endif /* _ASM_MICROBLAZE_UACCESS_H */

arch/microblaze/kernel/microblaze_ksyms.c

@@ -26,7 +26,6 @@ EXPORT_SYMBOL(_mcount);
  * Assembly functions that may be used (directly or indirectly) by modules
  */
 EXPORT_SYMBOL(__copy_tofrom_user);
-EXPORT_SYMBOL(__strncpy_user);
 
 #ifdef CONFIG_OPT_LIB_ASM
 EXPORT_SYMBOL(memcpy);

arch/microblaze/lib/uaccess_old.S

@@ -12,96 +12,6 @@
 #include <linux/linkage.h>
 #include <asm/page.h>
 
-/*
- * int __strncpy_user(char *to, char *from, int len);
- *
- * Returns:
- *  -EFAULT  for an exception
- *  len      if we hit the buffer limit
- *  bytes copied
- */
-
-	.text
-.globl __strncpy_user;
-.type  __strncpy_user, @function
-.align 4;
-__strncpy_user:
-
-	/*
-	 * r5 - to
-	 * r6 - from
-	 * r7 - len
-	 * r3 - temp count
-	 * r4 - temp val
-	 */
-	beqid	r7,3f
-	addik	r3,r7,0		/* temp_count = len */
-1:
-	lbu	r4,r6,r0
-	beqid	r4,2f
-	sb	r4,r5,r0
-
-	addik	r5,r5,1
-	addik	r6,r6,1		/* delay slot */
-
-	addik	r3,r3,-1
-	bnei	r3,1b		/* break on len */
-2:
-	rsubk	r3,r3,r7	/* temp_count = len - temp_count */
-3:
-	rtsd	r15,8
-	nop
-	.size   __strncpy_user, . - __strncpy_user
-
-	.section	.fixup, "ax"
-	.align	2
-4:
-	brid	3b
-	addik	r3,r0, -EFAULT
-
-	.section	__ex_table, "a"
-	.word	1b,4b
-
-/*
- * int __strnlen_user(char __user *str, int maxlen);
- *
- * Returns:
- *  0 on error
- *  maxlen + 1  if no NUL byte found within maxlen bytes
- *  size of the string (including NUL byte)
- */
-
-	.text
-.globl __strnlen_user;
-.type  __strnlen_user, @function
-.align 4;
-__strnlen_user:
-	beqid	r6,3f
-	addik	r3,r6,0
-1:
-	lbu	r4,r5,r0
-	beqid	r4,2f		/* break on NUL */
-	addik	r3,r3,-1	/* delay slot */
-
-	bneid	r3,1b
-	addik	r5,r5,1		/* delay slot */
-
-	addik	r3,r3,-1	/* for break on len */
-2:
-	rsubk	r3,r3,r6
-3:
-	rtsd	r15,8
-	nop
-	.size   __strnlen_user, . - __strnlen_user
-
-	.section	.fixup,"ax"
-4:
-	brid	3b
-	addk	r3,r0,r0
-
-	.section	__ex_table,"a"
-	.word	1b,4b
-
 /* Loop unrolling for __copy_tofrom_user */
 #define COPY(offset)	\
 1:	lwi	r4 , r6, 0x0000 + offset;	\