1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __TOOLS_LINUX_ERR_H
3 #define __TOOLS_LINUX_ERR_H
4
5 #include <linux/compiler.h>
6 #include <linux/types.h>
7
8 #include <asm/errno.h>
9
10 /*
11 * Original kernel header comment:
12 *
13 * Kernel pointers have redundant information, so we can use a
14 * scheme where we can return either an error code or a normal
15 * pointer with the same return value.
16 *
17 * This should be a per-architecture thing, to allow different
18 * error and pointer decisions.
19 *
20 * Userspace note:
21 * The same principle works for userspace, because 'error' pointers
22 * fall down to the unused hole far from user space, as described
23 * in Documentation/arch/x86/x86_64/mm.rst for x86_64 arch:
24 *
25 * 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
26 * ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
27 *
28 * It should be the same case for other architectures, because
29 * this code is used in generic kernel code.
30 */
31 #define MAX_ERRNO 4095
32
33 #define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
34
35 static inline void * __must_check ERR_PTR(long error_)
36 {
37 return (void *) error_;
38 }
39
40 static inline long __must_check PTR_ERR(__force const void *ptr)
41 {
42 return (long) ptr;
43 }
44
45 static inline bool __must_check IS_ERR(__force const void *ptr)
46 {
47 return IS_ERR_VALUE((unsigned long)ptr);
48 }
49
50 static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
51 {
52 return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
53 }
54
55 static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
56 {
57 if (IS_ERR(ptr))
58 return PTR_ERR(ptr);
59 else
60 return 0;
61 }
62
63 /**
64 * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
65 * @ptr: The pointer to cast.
66 *
67 * Explicitly cast an error-valued pointer to another pointer type in such a
68 * way as to make it clear that's what's going on.
69 */
70 static inline void * __must_check ERR_CAST(__force const void *ptr)
71 {
72 /* cast away the const */
73 return (void *) ptr;
74 }
75 #endif /* _LINUX_ERR_H */
76
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