riscv: use memcpy based uaccess for nommu again

This reverts commit adccfb1.

Now that the generic uaccess by mempcy code handles unaligned addresses
the generic code can be used for all RISC-V CPUs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -88,6 +88,7 @@ config RISCV
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
 	select SET_FS
+	select UACCESS_MEMCPY if !MMU
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT

arch/riscv/include/asm/uaccess.h

@@ -13,24 +13,6 @@
 /*
  * User space memory access functions
  */
-
-extern unsigned long __must_check __asm_copy_to_user(void __user *to,
-	const void *from, unsigned long n);
-extern unsigned long __must_check __asm_copy_from_user(void *to,
-	const void __user *from, unsigned long n);
-
-static inline unsigned long
-raw_copy_from_user(void *to, const void __user *from, unsigned long n)
-{
-	return __asm_copy_from_user(to, from, n);
-}
-
-static inline unsigned long
-raw_copy_to_user(void __user *to, const void *from, unsigned long n)
-{
-	return __asm_copy_to_user(to, from, n);
-}
-
 #ifdef CONFIG_MMU
 #include <linux/errno.h>
 #include <linux/compiler.h>
@@ -385,6 +367,24 @@ do {								\
 		-EFAULT;					\
 })
 
+
+unsigned long __must_check __asm_copy_to_user(void __user *to,
+	const void *from, unsigned long n);
+unsigned long __must_check __asm_copy_from_user(void *to,
+	const void __user *from, unsigned long n);
+
+static inline unsigned long
+raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	return __asm_copy_from_user(to, from, n);
+}
+
+static inline unsigned long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	return __asm_copy_to_user(to, from, n);
+}
+
 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 
 extern long __must_check strlen_user(const char __user *str);

arch/riscv/lib/Makefile

@@ -2,5 +2,5 @@
 lib-y			+= delay.o
 lib-y			+= memcpy.o
 lib-y			+= memset.o
-lib-y			+= uaccess.o
+lib-$(CONFIG_MMU)	+= uaccess.o
 lib-$(CONFIG_64BIT)	+= tishift.o