arch/x86/include/asm/uaccess_64.h

#ifndef _ASM_X86_UACCESS_64_H
#define _ASM_X86_UACCESS_64_H

/*
 * User space memory access functions
 */
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/prefetch.h>
#include <linux/lockdep.h>
#include <asm/page.h>

/*
 * Copy To/From Userspace
 */

/* Handles exceptions in both to and from, but doesn't do access_ok */
__must_check unsigned long
copy_user_generic(void *to, const void *from, unsigned len);

__must_check unsigned long
copy_to_user(void __user *to, const void *from, unsigned len);
__must_check unsigned long
copy_from_user(void *to, const void __user *from, unsigned len);
__must_check unsigned long
copy_in_user(void __user *to, const void __user *from, unsigned len);

static __always_inline __must_check
int __copy_from_user(void *dst, const void __user *src, unsigned size)
{
	int ret = 0;

	might_fault();
	if (!__builtin_constant_p(size))
		return copy_user_generic(dst, (__force void *)src, size);
	switch (size) {
	case 1:__get_user_asm(*(u8 *)dst, (u8 __user *)src,
			      ret, "b", "b", "=q", 1);
		return ret;
	case 2:__get_user_asm(*(u16 *)dst, (u16 __user *)src,
			      ret, "w", "w", "=r", 2);
		return ret;
	case 4:__get_user_asm(*(u32 *)dst, (u32 __user *)src,
			      ret, "l", "k", "=r", 4);
		return ret;
	case 8:__get_user_asm(*(u64 *)dst, (u64 __user *)src,
			      ret, "q", "", "=r", 8);
		return ret;
	case 10:
		__get_user_asm(*(u64 *)dst, (u64 __user *)src,
			       ret, "q", "", "=r", 10);
		if (unlikely(ret))
			return ret;
		__get_user_asm(*(u16 *)(8 + (char *)dst),
			       (u16 __user *)(8 + (char __user *)src),
			       ret, "w", "w", "=r", 2);
		return ret;
	case 16:
		__get_user_asm(*(u64 *)dst, (u64 __user *)src,
			       ret, "q", "", "=r", 16);
		if (unlikely(ret))
			return ret;
		__get_user_asm(*(u64 *)(8 + (char *)dst),
			       (u64 __user *)(8 + (char __user *)src),
			       ret, "q", "", "=r", 8);
		return ret;
	default:
		return copy_user_generic(dst, (__force void *)src, size);
	}
}

static __always_inline __must_check
int __copy_to_user(void __user *dst, const void *src, unsigned size)
{
	int ret = 0;

	might_fault();
	if (!__builtin_constant_p(size))
		return copy_user_generic((__force void *)dst, src, size);
	switch (size) {
	case 1:__put_user_asm(*(u8 *)src, (u8 __user *)dst,
			      ret, "b", "b", "iq", 1);
		return ret;
	case 2:__put_user_asm(*(u16 *)src, (u16 __user *)dst,
			      ret, "w", "w", "ir", 2);
		return ret;
	case 4:__put_user_asm(*(u32 *)src, (u32 __user *)dst,
			      ret, "l", "k", "ir", 4);
		return ret;
	case 8:__put_user_asm(*(u64 *)src, (u64 __user *)dst,
			      ret, "q", "", "ir", 8);
		return ret;
	case 10:
		__put_user_asm(*(u64 *)src, (u64 __user *)dst,
			       ret, "q", "", "ir", 10);
		if (unlikely(ret))
			return ret;
		asm("":::"memory");
		__put_user_asm(4[(u16 *)src], 4 + (u16 __user *)dst,
			       ret, "w", "w", "ir", 2);
		return ret;
	case 16:
		__put_user_asm(*(u64 *)src, (u64 __user *)dst,
			       ret, "q", "", "ir", 16);
		if (unlikely(ret))
			return ret;
		asm("":::"memory");
		__put_user_asm(1[(u64 *)src], 1 + (u64 __user *)dst,
			       ret, "q", "", "ir", 8);
		return ret;
	default:
		return copy_user_generic((__force void *)dst, src, size);
	}
}

static __always_inline __must_check
int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
{
	int ret = 0;

	might_fault();
	if (!__builtin_constant_p(size))
		return copy_user_generic((__force void *)dst,
					 (__force void *)src, size);
	switch (size) {
	case 1: {
		u8 tmp;
		__get_user_asm(tmp, (u8 __user *)src,
			       ret, "b", "b", "=q", 1);
		if (likely(!ret))
			__put_user_asm(tmp, (u8 __user *)dst,
				       ret, "b", "b", "iq", 1);
		return ret;
	}
	case 2: {
		u16 tmp;
		__get_user_asm(tmp, (u16 __user *)src,
			       ret, "w", "w", "=r", 2);
		if (likely(!ret))
			__put_user_asm(tmp, (u16 __user *)dst,
				       ret, "w", "w", "ir", 2);
		return ret;
	}

	case 4: {
		u32 tmp;
		__get_user_asm(tmp, (u32 __user *)src,
			       ret, "l", "k", "=r", 4);
		if (likely(!ret))
			__put_user_asm(tmp, (u32 __user *)dst,
				       ret, "l", "k", "ir", 4);
		return ret;
	}
	case 8: {
		u64 tmp;
		__get_user_asm(tmp, (u64 __user *)src,
			       ret, "q", "", "=r", 8);
		if (likely(!ret))
			__put_user_asm(tmp, (u64 __user *)dst,
				       ret, "q", "", "ir", 8);
		return ret;
	}
	default:
		return copy_user_generic((__force void *)dst,
					 (__force void *)src, size);
	}
}

__must_check long
strncpy_from_user(char *dst, const char __user *src, long count);
__must_check long
__strncpy_from_user(char *dst, const char __user *src, long count);
__must_check long strnlen_user(const char __user *str, long n);
__must_check long __strnlen_user(const char __user *str, long n);
__must_check long strlen_user(const char __user *str);
__must_check unsigned long clear_user(void __user *mem, unsigned long len);
__must_check unsigned long __clear_user(void __user *mem, unsigned long len);

__must_check long __copy_from_user_inatomic(void *dst, const void __user *src,
					    unsigned size);

static __must_check __always_inline int
__copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
{
	return copy_user_generic((__force void *)dst, src, size);
}

extern long __copy_user_nocache(void *dst, const void __user *src,
				unsigned size, int zerorest);

static inline int __copy_from_user_nocache(void *dst, const void __user *src,
					   unsigned size)
{
	might_sleep();
	/*
	 * In practice this limit means that large file write()s
	 * which get chunked to 4K copies get handled via
	 * non-temporal stores here. Smaller writes get handled
	 * via regular __copy_from_user():
	 */
	if (likely(size >= PAGE_SIZE))
		return __copy_user_nocache(dst, src, size, 1);
	else
		return __copy_from_user(dst, src, size);
}

static inline int __copy_from_user_inatomic_nocache(void *dst,
						    const void __user *src,
						    unsigned size)
{
	if (likely(size >= PAGE_SIZE))
		return __copy_user_nocache(dst, src, size, 0);
	else
		return __copy_from_user_inatomic(dst, src, size);
}

unsigned long
copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest);

#endif /* _ASM_X86_UACCESS_64_H */