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/module.h>
9#include <linux/interrupt.h>
10#include <linux/stacktrace.h>
11#include <linux/kallsyms.h>
12#include <linux/fault-inject.h>
13
14
15
16
17
18int __init setup_fault_attr(struct fault_attr *attr, char *str)
19{
20 unsigned long probability;
21 unsigned long interval;
22 int times;
23 int space;
24
25
26 if (sscanf(str, "%lu,%lu,%d,%d",
27 &interval, &probability, &space, ×) < 4) {
28 printk(KERN_WARNING
29 "FAULT_INJECTION: failed to parse arguments\n");
30 return 0;
31 }
32
33 attr->probability = probability;
34 attr->interval = interval;
35 atomic_set(&attr->times, times);
36 atomic_set(&attr->space, space);
37
38 return 1;
39}
40
41static void fail_dump(struct fault_attr *attr)
42{
43 if (attr->verbose > 0)
44 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
45 if (attr->verbose > 1)
46 dump_stack();
47}
48
49#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
50
51static bool fail_task(struct fault_attr *attr, struct task_struct *task)
52{
53 return !in_interrupt() && task->make_it_fail;
54}
55
56#define MAX_STACK_TRACE_DEPTH 32
57
58#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
59
60static bool fail_stacktrace(struct fault_attr *attr)
61{
62 struct stack_trace trace;
63 int depth = attr->stacktrace_depth;
64 unsigned long entries[MAX_STACK_TRACE_DEPTH];
65 int n;
66 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
67
68 if (depth == 0)
69 return found;
70
71 trace.nr_entries = 0;
72 trace.entries = entries;
73 trace.max_entries = depth;
74 trace.skip = 1;
75
76 save_stack_trace(&trace);
77 for (n = 0; n < trace.nr_entries; n++) {
78 if (attr->reject_start <= entries[n] &&
79 entries[n] < attr->reject_end)
80 return false;
81 if (attr->require_start <= entries[n] &&
82 entries[n] < attr->require_end)
83 found = true;
84 }
85 return found;
86}
87
88#else
89
90static inline bool fail_stacktrace(struct fault_attr *attr)
91{
92 return true;
93}
94
95#endif
96
97
98
99
100
101
102bool should_fail(struct fault_attr *attr, ssize_t size)
103{
104 if (attr->task_filter && !fail_task(attr, current))
105 return false;
106
107 if (atomic_read(&attr->times) == 0)
108 return false;
109
110 if (atomic_read(&attr->space) > size) {
111 atomic_sub(size, &attr->space);
112 return false;
113 }
114
115 if (attr->interval > 1) {
116 attr->count++;
117 if (attr->count % attr->interval)
118 return false;
119 }
120
121 if (attr->probability <= random32() % 100)
122 return false;
123
124 if (!fail_stacktrace(attr))
125 return false;
126
127 fail_dump(attr);
128
129 if (atomic_read(&attr->times) != -1)
130 atomic_dec_not_zero(&attr->times);
131
132 return true;
133}
134
135#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
136
137static int debugfs_ul_set(void *data, u64 val)
138{
139 *(unsigned long *)data = val;
140 return 0;
141}
142
143#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
144static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
145{
146 *(unsigned long *)data =
147 val < MAX_STACK_TRACE_DEPTH ?
148 val : MAX_STACK_TRACE_DEPTH;
149 return 0;
150}
151#endif
152
153static int debugfs_ul_get(void *data, u64 *val)
154{
155 *val = *(unsigned long *)data;
156 return 0;
157}
158
159DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
160
161static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
162 struct dentry *parent, unsigned long *value)
163{
164 return debugfs_create_file(name, mode, parent, value, &fops_ul);
165}
166
167#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
168DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
169 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
170
171static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
172 const char *name, mode_t mode,
173 struct dentry *parent, unsigned long *value)
174{
175 return debugfs_create_file(name, mode, parent, value,
176 &fops_ul_MAX_STACK_TRACE_DEPTH);
177}
178#endif
179
180static int debugfs_atomic_t_set(void *data, u64 val)
181{
182 atomic_set((atomic_t *)data, val);
183 return 0;
184}
185
186static int debugfs_atomic_t_get(void *data, u64 *val)
187{
188 *val = atomic_read((atomic_t *)data);
189 return 0;
190}
191
192DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
193 debugfs_atomic_t_set, "%lld\n");
194
195static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
196 struct dentry *parent, atomic_t *value)
197{
198 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
199}
200
201void cleanup_fault_attr_dentries(struct fault_attr *attr)
202{
203 debugfs_remove(attr->dentries.probability_file);
204 attr->dentries.probability_file = NULL;
205
206 debugfs_remove(attr->dentries.interval_file);
207 attr->dentries.interval_file = NULL;
208
209 debugfs_remove(attr->dentries.times_file);
210 attr->dentries.times_file = NULL;
211
212 debugfs_remove(attr->dentries.space_file);
213 attr->dentries.space_file = NULL;
214
215 debugfs_remove(attr->dentries.verbose_file);
216 attr->dentries.verbose_file = NULL;
217
218 debugfs_remove(attr->dentries.task_filter_file);
219 attr->dentries.task_filter_file = NULL;
220
221#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
222
223 debugfs_remove(attr->dentries.stacktrace_depth_file);
224 attr->dentries.stacktrace_depth_file = NULL;
225
226 debugfs_remove(attr->dentries.require_start_file);
227 attr->dentries.require_start_file = NULL;
228
229 debugfs_remove(attr->dentries.require_end_file);
230 attr->dentries.require_end_file = NULL;
231
232 debugfs_remove(attr->dentries.reject_start_file);
233 attr->dentries.reject_start_file = NULL;
234
235 debugfs_remove(attr->dentries.reject_end_file);
236 attr->dentries.reject_end_file = NULL;
237
238#endif
239
240 if (attr->dentries.dir)
241 WARN_ON(!simple_empty(attr->dentries.dir));
242
243 debugfs_remove(attr->dentries.dir);
244 attr->dentries.dir = NULL;
245}
246
247int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
248{
249 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
250 struct dentry *dir;
251
252 memset(&attr->dentries, 0, sizeof(attr->dentries));
253
254 dir = debugfs_create_dir(name, NULL);
255 if (!dir)
256 goto fail;
257 attr->dentries.dir = dir;
258
259 attr->dentries.probability_file =
260 debugfs_create_ul("probability", mode, dir, &attr->probability);
261
262 attr->dentries.interval_file =
263 debugfs_create_ul("interval", mode, dir, &attr->interval);
264
265 attr->dentries.times_file =
266 debugfs_create_atomic_t("times", mode, dir, &attr->times);
267
268 attr->dentries.space_file =
269 debugfs_create_atomic_t("space", mode, dir, &attr->space);
270
271 attr->dentries.verbose_file =
272 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
273
274 attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
275 mode, dir, &attr->task_filter);
276
277 if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
278 !attr->dentries.times_file || !attr->dentries.space_file ||
279 !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
280 goto fail;
281
282#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
283
284 attr->dentries.stacktrace_depth_file =
285 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
286 "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
287
288 attr->dentries.require_start_file =
289 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
290
291 attr->dentries.require_end_file =
292 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
293
294 attr->dentries.reject_start_file =
295 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
296
297 attr->dentries.reject_end_file =
298 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
299
300 if (!attr->dentries.stacktrace_depth_file ||
301 !attr->dentries.require_start_file ||
302 !attr->dentries.require_end_file ||
303 !attr->dentries.reject_start_file ||
304 !attr->dentries.reject_end_file)
305 goto fail;
306
307#endif
308
309 return 0;
310fail:
311 cleanup_fault_attr_dentries(attr);
312 return -ENOMEM;
313}
314
315#endif
316
