1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2 #ifndef __LIBPERF_INTERNAL_RC_CHECK_H
3 #define __LIBPERF_INTERNAL_RC_CHECK_H
4
5 #include <stdlib.h>
6 #include <linux/zalloc.h>
7
8 /*
9 * Enable reference count checking implicitly with leak checking, which is
10 * integrated into address sanitizer.
11 */
12 #if defined(__SANITIZE_ADDRESS__) || defined(LEAK_SANITIZER) || defined(ADDRESS_SANITIZER)
13 #define REFCNT_CHECKING 1
14 #elif defined(__has_feature)
15 #if __has_feature(address_sanitizer) || __has_feature(leak_sanitizer)
16 #define REFCNT_CHECKING 1
17 #endif
18 #endif
19
20 /*
21 * Shared reference count checking macros.
22 *
23 * Reference count checking is an approach to sanitizing the use of reference
24 * counted structs. It leverages address and leak sanitizers to make sure gets
25 * are paired with a put. Reference count checking adds a malloc-ed layer of
26 * indirection on a get, and frees it on a put. A missed put will be reported as
27 * a memory leak. A double put will be reported as a double free. Accessing
28 * after a put will cause a use-after-free and/or a segfault.
29 */
30
31 #ifndef REFCNT_CHECKING
32 /* Replaces "struct foo" so that the pointer may be interposed. */
33 #define DECLARE_RC_STRUCT(struct_name) \
34 struct struct_name
35
36 /* Declare a reference counted struct variable. */
37 #define RC_STRUCT(struct_name) struct struct_name
38
39 /*
40 * Interpose the indirection. Result will hold the indirection and object is the
41 * reference counted struct.
42 */
43 #define ADD_RC_CHK(result, object) (result = object, object)
44
45 /* Strip the indirection layer. */
46 #define RC_CHK_ACCESS(object) object
47
48 /* Frees the object and the indirection layer. */
49 #define RC_CHK_FREE(object) free(object)
50
51 /* A get operation adding the indirection layer. */
52 #define RC_CHK_GET(result, object) ADD_RC_CHK(result, object)
53
54 /* A put operation removing the indirection layer. */
55 #define RC_CHK_PUT(object) {}
56
57 /* Pointer equality when the indirection may or may not be there. */
58 #define RC_CHK_EQUAL(object1, object2) (object1 == object2)
59
60 #else
61
62 /* Replaces "struct foo" so that the pointer may be interposed. */
63 #define DECLARE_RC_STRUCT(struct_name) \
64 struct original_##struct_name; \
65 struct struct_name { \
66 struct original_##struct_name *orig; \
67 }; \
68 struct original_##struct_name
69
70 /* Declare a reference counted struct variable. */
71 #define RC_STRUCT(struct_name) struct original_##struct_name
72
73 /*
74 * Interpose the indirection. Result will hold the indirection and object is the
75 * reference counted struct.
76 */
77 #define ADD_RC_CHK(result, object) \
78 ( \
79 object ? (result = malloc(sizeof(*result)), \
80 result ? (result->orig = object, result) \
81 : (result = NULL, NULL)) \
82 : (result = NULL, NULL) \
83 )
84
85 /* Strip the indirection layer. */
86 #define RC_CHK_ACCESS(object) object->orig
87
88 /* Frees the object and the indirection layer. */
89 #define RC_CHK_FREE(object) \
90 do { \
91 zfree(&object->orig); \
92 free(object); \
93 } while(0)
94
95 /* A get operation adding the indirection layer. */
96 #define RC_CHK_GET(result, object) ADD_RC_CHK(result, (object ? object->orig : NULL))
97
98 /* A put operation removing the indirection layer. */
99 #define RC_CHK_PUT(object) \
100 do { \
101 if (object) { \
102 object->orig = NULL; \
103 free(object); \
104 } \
105 } while(0)
106
107 /* Pointer equality when the indirection may or may not be there. */
108 #define RC_CHK_EQUAL(object1, object2) (object1 == object2 || \
109 (object1 && object2 && object1->orig == object2->orig))
110
111 #endif
112
113 #endif /* __LIBPERF_INTERNAL_RC_CHECK_H */
114
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.