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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef __ASM_GENERIC_ACCESS_OK_H__3#define __ASM_GENERIC_ACCESS_OK_H__4 5/*6 * Checking whether a pointer is valid for user space access.7 * These definitions work on most architectures, but overrides can8 * be used where necessary.9 */10 11/*12 * architectures with compat tasks have a variable TASK_SIZE and should13 * override this to a constant.14 */15#ifndef TASK_SIZE_MAX16#define TASK_SIZE_MAX TASK_SIZE17#endif18 19#ifndef __access_ok20/*21 * 'size' is a compile-time constant for most callers, so optimize for22 * this case to turn the check into a single comparison against a constant23 * limit and catch all possible overflows.24 * On architectures with separate user address space (m68k, s390, parisc,25 * sparc64) or those without an MMU, this should always return true.26 *27 * This version was originally contributed by Jonas Bonn for the28 * OpenRISC architecture, and was found to be the most efficient29 * for constant 'size' and 'limit' values.30 */31static inline int __access_ok(const void __user *ptr, unsigned long size)32{33 unsigned long limit = TASK_SIZE_MAX;34 unsigned long addr = (unsigned long)ptr;35 36 if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||37 !IS_ENABLED(CONFIG_MMU))38 return true;39 40 return (size <= limit) && (addr <= (limit - size));41}42#endif43 44#ifndef access_ok45#define access_ok(addr, size) likely(__access_ok(addr, size))46#endif47 48#endif49