riscv: implement __get_kernel_nofault and __put_user_nofault

Implement the non-faulting kernel access helpers directly instead of
abusing the uaccess routines under set_fs(KERNEL_DS).

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

diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index b67d1c6..264e52f 100644 (file)
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -486,6 +486,26 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n)
        __ret;                                                  \
 })
 
+#define HAVE_GET_KERNEL_NOFAULT
+
+#define __get_kernel_nofault(dst, src, type, err_label)                        \
+do {                                                                   \
+       long __kr_err;                                                  \
+                                                                       \
+       __get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);  \
+       if (unlikely(__kr_err))                                         \
+               goto err_label;                                         \
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label)                        \
+do {                                                                   \
+       long __kr_err;                                                  \
+                                                                       \
+       __put_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err);  \
+       if (unlikely(__kr_err))                                         \
+               goto err_label;                                         \
+} while (0)
+
 #else /* CONFIG_MMU */
 #include <asm-generic/uaccess.h>
 #endif /* CONFIG_MMU */