1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <linux/random.h>
4 #include <linux/stat.h>
5 #include <linux/types.h>
6 #include <linux/fs.h>
7 #include <linux/module.h>
8 #include <linux/interrupt.h>
9 #include <linux/stacktrace.h>
10 #include <linux/kallsyms.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 __init 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
40 static void fail_dump(struct fault_attr *attr)
41 {
42 if (attr->verbose > 0)
43 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
44 if (attr->verbose > 1)
45 dump_stack();
46 }
47
48 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
49
50 static bool fail_task(struct fault_attr *attr, struct task_struct *task)
51 {
52 return !in_interrupt() && task->make_it_fail;
53 }
54
55 #define MAX_STACK_TRACE_DEPTH 32
56
57 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
58
59 static bool fail_stacktrace(struct fault_attr *attr)
60 {
61 struct stack_trace trace;
62 int depth = attr->stacktrace_depth;
63 unsigned long entries[MAX_STACK_TRACE_DEPTH];
64 int n;
65 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
66
67 if (depth == 0)
68 return found;
69
70 trace.nr_entries = 0;
71 trace.entries = entries;
72 trace.max_entries = depth;
73 trace.skip = 1;
74
75 save_stack_trace(&trace);
76 for (n = 0; n < trace.nr_entries; n++) {
77 if (attr->reject_start <= entries[n] &&
78 entries[n] < attr->reject_end)
79 return false;
80 if (attr->require_start <= entries[n] &&
81 entries[n] < attr->require_end)
82 found = true;
83 }
84 return found;
85 }
86
87 #else
88
89 static inline bool fail_stacktrace(struct fault_attr *attr)
90 {
91 return true;
92 }
93
94 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
95
96 /*
97 * This code is stolen from failmalloc-1.0
98 * http://www.nongnu.org/failmalloc/
99 */
100
101 bool should_fail(struct fault_attr *attr, ssize_t size)
102 {
103 if (attr->task_filter && !fail_task(attr, current))
104 return false;
105
106 if (atomic_read(&attr->times) == 0)
107 return false;
108
109 if (atomic_read(&attr->space) > size) {
110 atomic_sub(size, &attr->space);
111 return false;
112 }
113
114 if (attr->interval > 1) {
115 attr->count++;
116 if (attr->count % attr->interval)
117 return false;
118 }
119
120 if (attr->probability <= random32() % 100)
121 return false;
122
123 if (!fail_stacktrace(attr))
124 return false;
125
126 fail_dump(attr);
127
128 if (atomic_read(&attr->times) != -1)
129 atomic_dec_not_zero(&attr->times);
130
131 return true;
132 }
133
134 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
135
136 static int debugfs_ul_set(void *data, u64 val)
137 {
138 *(unsigned long *)data = val;
139 return 0;
140 }
141
142 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
143 static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
144 {
145 *(unsigned long *)data =
146 val < MAX_STACK_TRACE_DEPTH ?
147 val : MAX_STACK_TRACE_DEPTH;
148 return 0;
149 }
150 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
151
152 static int debugfs_ul_get(void *data, u64 *val)
153 {
154 *val = *(unsigned long *)data;
155 return 0;
156 }
157
158 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
159
160 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
161 struct dentry *parent, unsigned long *value)
162 {
163 return debugfs_create_file(name, mode, parent, value, &fops_ul);
164 }
165
166 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
167 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
168 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
169
170 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
171 const char *name, mode_t mode,
172 struct dentry *parent, unsigned long *value)
173 {
174 return debugfs_create_file(name, mode, parent, value,
175 &fops_ul_MAX_STACK_TRACE_DEPTH);
176 }
177 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
178
179 static int debugfs_atomic_t_set(void *data, u64 val)
180 {
181 atomic_set((atomic_t *)data, val);
182 return 0;
183 }
184
185 static int debugfs_atomic_t_get(void *data, u64 *val)
186 {
187 *val = atomic_read((atomic_t *)data);
188 return 0;
189 }
190
191 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
192 debugfs_atomic_t_set, "%lld\n");
193
194 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
195 struct dentry *parent, atomic_t *value)
196 {
197 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
198 }
199
200 void cleanup_fault_attr_dentries(struct fault_attr *attr)
201 {
202 debugfs_remove(attr->dentries.probability_file);
203 attr->dentries.probability_file = NULL;
204
205 debugfs_remove(attr->dentries.interval_file);
206 attr->dentries.interval_file = NULL;
207
208 debugfs_remove(attr->dentries.times_file);
209 attr->dentries.times_file = NULL;
210
211 debugfs_remove(attr->dentries.space_file);
212 attr->dentries.space_file = NULL;
213
214 debugfs_remove(attr->dentries.verbose_file);
215 attr->dentries.verbose_file = NULL;
216
217 debugfs_remove(attr->dentries.task_filter_file);
218 attr->dentries.task_filter_file = NULL;
219
220 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221
222 debugfs_remove(attr->dentries.stacktrace_depth_file);
223 attr->dentries.stacktrace_depth_file = NULL;
224
225 debugfs_remove(attr->dentries.require_start_file);
226 attr->dentries.require_start_file = NULL;
227
228 debugfs_remove(attr->dentries.require_end_file);
229 attr->dentries.require_end_file = NULL;
230
231 debugfs_remove(attr->dentries.reject_start_file);
232 attr->dentries.reject_start_file = NULL;
233
234 debugfs_remove(attr->dentries.reject_end_file);
235 attr->dentries.reject_end_file = NULL;
236
237 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
238
239 if (attr->dentries.dir)
240 WARN_ON(!simple_empty(attr->dentries.dir));
241
242 debugfs_remove(attr->dentries.dir);
243 attr->dentries.dir = NULL;
244 }
245
246 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
247 {
248 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
249 struct dentry *dir;
250
251 memset(&attr->dentries, 0, sizeof(attr->dentries));
252
253 dir = debugfs_create_dir(name, NULL);
254 if (!dir)
255 goto fail;
256 attr->dentries.dir = dir;
257
258 attr->dentries.probability_file =
259 debugfs_create_ul("probability", mode, dir, &attr->probability);
260
261 attr->dentries.interval_file =
262 debugfs_create_ul("interval", mode, dir, &attr->interval);
263
264 attr->dentries.times_file =
265 debugfs_create_atomic_t("times", mode, dir, &attr->times);
266
267 attr->dentries.space_file =
268 debugfs_create_atomic_t("space", mode, dir, &attr->space);
269
270 attr->dentries.verbose_file =
271 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
272
273 attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
274 mode, dir, &attr->task_filter);
275
276 if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
277 !attr->dentries.times_file || !attr->dentries.space_file ||
278 !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
279 goto fail;
280
281 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
282
283 attr->dentries.stacktrace_depth_file =
284 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
285 "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
286
287 attr->dentries.require_start_file =
288 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
289
290 attr->dentries.require_end_file =
291 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
292
293 attr->dentries.reject_start_file =
294 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
295
296 attr->dentries.reject_end_file =
297 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
298
299 if (!attr->dentries.stacktrace_depth_file ||
300 !attr->dentries.require_start_file ||
301 !attr->dentries.require_end_file ||
302 !attr->dentries.reject_start_file ||
303 !attr->dentries.reject_end_file)
304 goto fail;
305
306 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
307
308 return 0;
309 fail:
310 cleanup_fault_attr_dentries(attr);
311 return -ENOMEM;
312 }
313
314 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
315
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