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 can |
8 | * be used where necessary. |
9 | */ |
10 | |
11 | /* |
12 | * architectures with compat tasks have a variable TASK_SIZE and should |
13 | * override this to a constant. |
14 | */ |
15 | #ifndef TASK_SIZE_MAX |
16 | #define TASK_SIZE_MAX TASK_SIZE |
17 | #endif |
18 | |
19 | #ifndef __access_ok |
20 | /* |
21 | * 'size' is a compile-time constant for most callers, so optimize for |
22 | * this case to turn the check into a single comparison against a constant |
23 | * 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 the |
28 | * OpenRISC architecture, and was found to be the most efficient |
29 | * for constant 'size' and 'limit' values. |
30 | */ |
31 | static 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 | #endif |
43 | |
44 | #ifndef access_ok |
45 | #define access_ok(addr, size) likely(__access_ok(addr, size)) |
46 | #endif |
47 | |
48 | #endif |
49 | |