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1 | #include <linux/kernel.h> | |
2 | #include <linux/init.h> | |
3 | #include <linux/random.h> | |
4 | #include <linux/sched.h> | |
5 | #include <linux/stat.h> | |
6 | #include <linux/types.h> | |
7 | #include <linux/fs.h> | |
8 | #include <linux/export.h> | |
9 | #include <linux/interrupt.h> | |
10 | #include <linux/stacktrace.h> | |
11 | #include <linux/fault-inject.h> | |
12 | ||
13 | /* | |
14 | * setup_fault_attr() is a helper function for various __setup handlers, so it | |
15 | * returns 0 on error, because that is what __setup handlers do. | |
16 | */ | |
17 | int setup_fault_attr(struct fault_attr *attr, char *str) | |
18 | { | |
19 | unsigned long probability; | |
20 | unsigned long interval; | |
21 | int times; | |
22 | int space; | |
23 | ||
24 | /* "<interval>,<probability>,<space>,<times>" */ | |
25 | if (sscanf(str, "%lu,%lu,%d,%d", | |
26 | &interval, &probability, &space, ×) < 4) { | |
27 | printk(KERN_WARNING | |
28 | "FAULT_INJECTION: failed to parse arguments\n"); | |
29 | return 0; | |
30 | } | |
31 | ||
32 | attr->probability = probability; | |
33 | attr->interval = interval; | |
34 | atomic_set(&attr->times, times); | |
35 | atomic_set(&attr->space, space); | |
36 | ||
37 | return 1; | |
38 | } | |
39 | EXPORT_SYMBOL_GPL(setup_fault_attr); | |
40 | ||
41 | static void fail_dump(struct fault_attr *attr) | |
42 | { | |
43 | if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) { | |
44 | printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n" | |
45 | "name %pd, interval %lu, probability %lu, " | |
46 | "space %d, times %d\n", attr->dname, | |
47 | attr->interval, attr->probability, | |
48 | atomic_read(&attr->space), | |
49 | atomic_read(&attr->times)); | |
50 | if (attr->verbose > 1) | |
51 | dump_stack(); | |
52 | } | |
53 | } | |
54 | ||
55 | #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) | |
56 | ||
57 | static bool fail_task(struct fault_attr *attr, struct task_struct *task) | |
58 | { | |
59 | return in_task() && task->make_it_fail; | |
60 | } | |
61 | ||
62 | #define MAX_STACK_TRACE_DEPTH 32 | |
63 | ||
64 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
65 | ||
66 | static bool fail_stacktrace(struct fault_attr *attr) | |
67 | { | |
68 | struct stack_trace trace; | |
69 | int depth = attr->stacktrace_depth; | |
70 | unsigned long entries[MAX_STACK_TRACE_DEPTH]; | |
71 | int n; | |
72 | bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); | |
73 | ||
74 | if (depth == 0) | |
75 | return found; | |
76 | ||
77 | trace.nr_entries = 0; | |
78 | trace.entries = entries; | |
79 | trace.max_entries = depth; | |
80 | trace.skip = 1; | |
81 | ||
82 | save_stack_trace(&trace); | |
83 | for (n = 0; n < trace.nr_entries; n++) { | |
84 | if (attr->reject_start <= entries[n] && | |
85 | entries[n] < attr->reject_end) | |
86 | return false; | |
87 | if (attr->require_start <= entries[n] && | |
88 | entries[n] < attr->require_end) | |
89 | found = true; | |
90 | } | |
91 | return found; | |
92 | } | |
93 | ||
94 | #else | |
95 | ||
96 | static inline bool fail_stacktrace(struct fault_attr *attr) | |
97 | { | |
98 | return true; | |
99 | } | |
100 | ||
101 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
102 | ||
103 | /* | |
104 | * This code is stolen from failmalloc-1.0 | |
105 | * http://www.nongnu.org/failmalloc/ | |
106 | */ | |
107 | ||
108 | bool should_fail(struct fault_attr *attr, ssize_t size) | |
109 | { | |
110 | if (in_task()) { | |
111 | unsigned int fail_nth = READ_ONCE(current->fail_nth); | |
112 | ||
113 | if (fail_nth) { | |
114 | if (!WRITE_ONCE(current->fail_nth, fail_nth - 1)) | |
115 | goto fail; | |
116 | ||
117 | return false; | |
118 | } | |
119 | } | |
120 | ||
121 | /* No need to check any other properties if the probability is 0 */ | |
122 | if (attr->probability == 0) | |
123 | return false; | |
124 | ||
125 | if (attr->task_filter && !fail_task(attr, current)) | |
126 | return false; | |
127 | ||
128 | if (atomic_read(&attr->times) == 0) | |
129 | return false; | |
130 | ||
131 | if (atomic_read(&attr->space) > size) { | |
132 | atomic_sub(size, &attr->space); | |
133 | return false; | |
134 | } | |
135 | ||
136 | if (attr->interval > 1) { | |
137 | attr->count++; | |
138 | if (attr->count % attr->interval) | |
139 | return false; | |
140 | } | |
141 | ||
142 | if (attr->probability <= prandom_u32() % 100) | |
143 | return false; | |
144 | ||
145 | if (!fail_stacktrace(attr)) | |
146 | return false; | |
147 | ||
148 | fail: | |
149 | fail_dump(attr); | |
150 | ||
151 | if (atomic_read(&attr->times) != -1) | |
152 | atomic_dec_not_zero(&attr->times); | |
153 | ||
154 | return true; | |
155 | } | |
156 | EXPORT_SYMBOL_GPL(should_fail); | |
157 | ||
158 | #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS | |
159 | ||
160 | static int debugfs_ul_set(void *data, u64 val) | |
161 | { | |
162 | *(unsigned long *)data = val; | |
163 | return 0; | |
164 | } | |
165 | ||
166 | static int debugfs_ul_get(void *data, u64 *val) | |
167 | { | |
168 | *val = *(unsigned long *)data; | |
169 | return 0; | |
170 | } | |
171 | ||
172 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); | |
173 | ||
174 | static struct dentry *debugfs_create_ul(const char *name, umode_t mode, | |
175 | struct dentry *parent, unsigned long *value) | |
176 | { | |
177 | return debugfs_create_file(name, mode, parent, value, &fops_ul); | |
178 | } | |
179 | ||
180 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
181 | ||
182 | static int debugfs_stacktrace_depth_set(void *data, u64 val) | |
183 | { | |
184 | *(unsigned long *)data = | |
185 | min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); | |
186 | ||
187 | return 0; | |
188 | } | |
189 | ||
190 | DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, | |
191 | debugfs_stacktrace_depth_set, "%llu\n"); | |
192 | ||
193 | static struct dentry *debugfs_create_stacktrace_depth( | |
194 | const char *name, umode_t mode, | |
195 | struct dentry *parent, unsigned long *value) | |
196 | { | |
197 | return debugfs_create_file(name, mode, parent, value, | |
198 | &fops_stacktrace_depth); | |
199 | } | |
200 | ||
201 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
202 | ||
203 | struct dentry *fault_create_debugfs_attr(const char *name, | |
204 | struct dentry *parent, struct fault_attr *attr) | |
205 | { | |
206 | umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; | |
207 | struct dentry *dir; | |
208 | ||
209 | dir = debugfs_create_dir(name, parent); | |
210 | if (!dir) | |
211 | return ERR_PTR(-ENOMEM); | |
212 | ||
213 | if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) | |
214 | goto fail; | |
215 | if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) | |
216 | goto fail; | |
217 | if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) | |
218 | goto fail; | |
219 | if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) | |
220 | goto fail; | |
221 | if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) | |
222 | goto fail; | |
223 | if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir, | |
224 | &attr->ratelimit_state.interval)) | |
225 | goto fail; | |
226 | if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir, | |
227 | &attr->ratelimit_state.burst)) | |
228 | goto fail; | |
229 | if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) | |
230 | goto fail; | |
231 | ||
232 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER | |
233 | ||
234 | if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, | |
235 | &attr->stacktrace_depth)) | |
236 | goto fail; | |
237 | if (!debugfs_create_ul("require-start", mode, dir, | |
238 | &attr->require_start)) | |
239 | goto fail; | |
240 | if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) | |
241 | goto fail; | |
242 | if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) | |
243 | goto fail; | |
244 | if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) | |
245 | goto fail; | |
246 | ||
247 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ | |
248 | ||
249 | attr->dname = dget(dir); | |
250 | return dir; | |
251 | fail: | |
252 | debugfs_remove_recursive(dir); | |
253 | ||
254 | return ERR_PTR(-ENOMEM); | |
255 | } | |
256 | EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); | |
257 | ||
258 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |