linux/arch/x86/include/asm/uaccess_64.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_UACCESS_64_H
#define _ASM_X86_UACCESS_64_H

/*
 * User space memory access functions
 */
#include <linux/compiler.h>
#include <linux/lockdep.h>
#include <linux/kasan-checks.h>
#include <asm/alternative.h>
#include <asm/cpufeatures.h>
#include <asm/page.h>
#include <asm/percpu.h>

#ifdef CONFIG_ADDRESS_MASKING
/*
 * Mask out tag bits from the address.
 */
static inline unsigned long __untagged_addr(unsigned long addr)
{ … }

#define untagged_addr(addr) …

static inline unsigned long __untagged_addr_remote(struct mm_struct *mm,
						   unsigned long addr)
{ … }

#define untagged_addr_remote(mm, addr) …

#endif

/*
 * The virtual address space space is logically divided into a kernel
 * half and a user half.  When cast to a signed type, user pointers
 * are positive and kernel pointers are negative.
 */
#define valid_user_address(x) …

/*
 * User pointers can have tag bits on x86-64.  This scheme tolerates
 * arbitrary values in those bits rather then masking them off.
 *
 * Enforce two rules:
 * 1. 'ptr' must be in the user half of the address space
 * 2. 'ptr+size' must not overflow into kernel addresses
 *
 * Note that addresses around the sign change are not valid addresses,
 * and will GP-fault even with LAM enabled if the sign bit is set (see
 * "CR3.LAM_SUP" that can narrow the canonicality check if we ever
 * enable it, but not remove it entirely).
 *
 * So the "overflow into kernel addresses" does not imply some sudden
 * exact boundary at the sign bit, and we can allow a lot of slop on the
 * size check.
 *
 * In fact, we could probably remove the size check entirely, since
 * any kernel accesses will be in increasing address order starting
 * at 'ptr', and even if the end might be in kernel space, we'll
 * hit the GP faults for non-canonical accesses before we ever get
 * there.
 *
 * That's a separate optimization, for now just handle the small
 * constant case.
 */
static inline bool __access_ok(const void __user *ptr, unsigned long size)
{ … }
#define __access_ok …

/*
 * Copy To/From Userspace
 */

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

static __always_inline __must_check unsigned long
copy_user_generic(void *to, const void *from, unsigned long len)
{ … }

static __always_inline __must_check unsigned long
raw_copy_from_user(void *dst, const void __user *src, unsigned long size)
{ … }

static __always_inline __must_check unsigned long
raw_copy_to_user(void __user *dst, const void *src, unsigned long size)
{ … }

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

static inline int
__copy_from_user_inatomic_nocache(void *dst, const void __user *src,
				  unsigned size)
{ … }

static inline int
__copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
{ … }

/*
 * Zero Userspace.
 */

__must_check unsigned long
rep_stos_alternative(void __user *addr, unsigned long len);

static __always_inline __must_check unsigned long __clear_user(void __user *addr, unsigned long size)
{ … }

static __always_inline unsigned long clear_user(void __user *to, unsigned long n)
{ … }
#endif /* _ASM_X86_UACCESS_64_H */