| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef __ASM_GENERIC_ACCESS_OK_H__ |
| #define __ASM_GENERIC_ACCESS_OK_H__ |
| |
| /* |
| * Checking whether a pointer is valid for user space access. |
| * These definitions work on most architectures, but overrides can |
| * be used where necessary. |
| */ |
| |
| /* |
| * architectures with compat tasks have a variable TASK_SIZE and should |
| * override this to a constant. |
| */ |
| #ifndef TASK_SIZE_MAX |
| #define TASK_SIZE_MAX TASK_SIZE |
| #endif |
| |
| #ifndef __access_ok |
| /* |
| * 'size' is a compile-time constant for most callers, so optimize for |
| * this case to turn the check into a single comparison against a constant |
| * limit and catch all possible overflows. |
| * On architectures with separate user address space (m68k, s390, parisc, |
| * sparc64) or those without an MMU, this should always return true. |
| * |
| * This version was originally contributed by Jonas Bonn for the |
| * OpenRISC architecture, and was found to be the most efficient |
| * for constant 'size' and 'limit' values. |
| */ |
| static inline int __access_ok(const void __user *ptr, unsigned long size) |
| { |
| unsigned long limit = TASK_SIZE_MAX; |
| unsigned long addr = (unsigned long)ptr; |
| |
| if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) || |
| !IS_ENABLED(CONFIG_MMU)) |
| return true; |
| |
| return (size <= limit) && (addr <= (limit - size)); |
| } |
| #endif |
| |
| #ifndef access_ok |
| #define access_ok(addr, size) likely(__access_ok(addr, size)) |
| #endif |
| |
| #endif |
