1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KUnit function redirection (static stubbing) API.
4 *
5 * Copyright (C) 2022, Google LLC.
6 * Author: David Gow <davidgow@google.com>
7 */
8
9 #include <kunit/test.h>
10 #include <kunit/static_stub.h>
11 #include "hooks-impl.h"
12
13
14 /* Context for a static stub. This is stored in the resource data. */
15 struct kunit_static_stub_ctx {
16 void *real_fn_addr;
17 void *replacement_addr;
18 };
19
20 static void __kunit_static_stub_resource_free(struct kunit_resource *res)
21 {
22 kfree(res->data);
23 }
24
25 /* Matching function for kunit_find_resource(). match_data is real_fn_addr. */
26 static bool __kunit_static_stub_resource_match(struct kunit *test,
27 struct kunit_resource *res,
28 void *match_real_fn_addr)
29 {
30 /* This pointer is only valid if res is a static stub resource. */
31 struct kunit_static_stub_ctx *ctx = res->data;
32
33 /* Make sure the resource is a static stub resource. */
34 if (res->free != &__kunit_static_stub_resource_free)
35 return false;
36
37 return ctx->real_fn_addr == match_real_fn_addr;
38 }
39
40 /* Hook to return the address of the replacement function. */
41 void *__kunit_get_static_stub_address_impl(struct kunit *test, void *real_fn_addr)
42 {
43 struct kunit_resource *res;
44 struct kunit_static_stub_ctx *ctx;
45 void *replacement_addr;
46
47 res = kunit_find_resource(test,
48 __kunit_static_stub_resource_match,
49 real_fn_addr);
50
51 if (!res)
52 return NULL;
53
54 ctx = res->data;
55 replacement_addr = ctx->replacement_addr;
56 kunit_put_resource(res);
57 return replacement_addr;
58 }
59
60 void kunit_deactivate_static_stub(struct kunit *test, void *real_fn_addr)
61 {
62 struct kunit_resource *res;
63
64 KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL,
65 "Tried to deactivate a NULL stub.");
66
67 /* Look up the existing stub for this function. */
68 res = kunit_find_resource(test,
69 __kunit_static_stub_resource_match,
70 real_fn_addr);
71
72 /* Error out if the stub doesn't exist. */
73 KUNIT_ASSERT_PTR_NE_MSG(test, res, NULL,
74 "Tried to deactivate a nonexistent stub.");
75
76 /* Free the stub. We 'put' twice, as we got a reference
77 * from kunit_find_resource()
78 */
79 kunit_remove_resource(test, res);
80 kunit_put_resource(res);
81 }
82 EXPORT_SYMBOL_GPL(kunit_deactivate_static_stub);
83
84 /* Helper function for kunit_activate_static_stub(). The macro does
85 * typechecking, so use it instead.
86 */
87 void __kunit_activate_static_stub(struct kunit *test,
88 void *real_fn_addr,
89 void *replacement_addr)
90 {
91 struct kunit_static_stub_ctx *ctx;
92 struct kunit_resource *res;
93
94 KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL,
95 "Tried to activate a stub for function NULL");
96
97 /* If the replacement address is NULL, deactivate the stub. */
98 if (!replacement_addr) {
99 kunit_deactivate_static_stub(test, replacement_addr);
100 return;
101 }
102
103 /* Look up any existing stubs for this function, and replace them. */
104 res = kunit_find_resource(test,
105 __kunit_static_stub_resource_match,
106 real_fn_addr);
107 if (res) {
108 ctx = res->data;
109 ctx->replacement_addr = replacement_addr;
110
111 /* We got an extra reference from find_resource(), so put it. */
112 kunit_put_resource(res);
113 } else {
114 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
115 KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
116 ctx->real_fn_addr = real_fn_addr;
117 ctx->replacement_addr = replacement_addr;
118 res = kunit_alloc_resource(test, NULL,
119 &__kunit_static_stub_resource_free,
120 GFP_KERNEL, ctx);
121 }
122 }
123 EXPORT_SYMBOL_GPL(__kunit_activate_static_stub);
124
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