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12700c17 AB |
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 | ||
12700c17 AB |
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 | { | |
967747bb | 33 | unsigned long limit = TASK_SIZE_MAX; |
12700c17 AB |
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 |