uaccess: add generic fallback version of copy_mc_to_user()

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GB28
CVE: NA

-------------------------------

x86/powerpc has it's implementation of copy_mc_to_user(), we add generic
fallback in include/linux/uaccess.h prepare for other architechures to
enable CONFIG_ARCH_HAS_COPY_MC.
Signed-off-by: NTong Tiangen <tongtiangen@huawei.com>

arch/powerpc/include/asm/uaccess.h

@@ -388,6 +388,7 @@ copy_mc_to_user(void __user *to, const void *from, unsigned long n)
 
 	return n;
 }
+#define copy_mc_to_user copy_mc_to_user
 #endif
 
 #ifdef __powerpc64__

arch/x86/include/asm/uaccess.h

@@ -447,6 +447,7 @@ copy_mc_to_kernel(void *to, const void *from, unsigned len);
 
 unsigned long __must_check
 copy_mc_to_user(void *to, const void *from, unsigned len);
+#define copy_mc_to_user copy_mc_to_user
 #endif
 
 /*

include/linux/uaccess.h

@@ -224,6 +224,15 @@ copy_mc_to_kernel(void *dst, const void *src, size_t cnt)
 }
 #endif
 
+#ifndef copy_mc_to_user
+static inline unsigned long __must_check
+copy_mc_to_user(void *dst, const void *src, size_t cnt)
+{
+	check_object_size(src, cnt, true);
+	return raw_copy_to_user(dst, src, cnt);
+}
+#endif
+
 static __always_inline void pagefault_disabled_inc(void)
 {
 	current->pagefault_disabled++;