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>
#include <asm/runtime-const.h>

/*
 * Virtual variable: there's no actual backing store for this,
 * it can purely be used as 'runtime_const_ptr(USER_PTR_MAX)'
 */
extern unsigned long USER_PTR_MAX;

#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

#define valid_user_address(x) …

/*
 * Masking the user address is an alternative to a conditional
 * user_access_begin that can avoid the fencing. This only works
 * for dense accesses starting at the address.
 */
static inline void __user *mask_user_address(const void __user *ptr)
{ … }
#define masked_user_access_begin(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 part of the address space
 * 2. 'ptr+size' must not overflow into kernel addresses
 *
 * Note that we always have at least one guard page between the
 * max user address and the non-canonical gap, allowing us to
 * ignore small sizes entirely.
 *
 * In fact, we could probably remove the size check entirely, since
 * any kernel accesses will be in increasing address order starting
 * at 'ptr'.
 *
 * 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 */