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/unwind.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 void debugfs_ul_set(void *data, u64 val)
138{
139 *(unsigned long *)data = val;
140}
141
142#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
143static void 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}
149#endif
150
151static u64 debugfs_ul_get(void *data)
152{
153 return *(unsigned long *)data;
154}
155
156DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
157
158static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
159 struct dentry *parent, unsigned long *value)
160{
161 return debugfs_create_file(name, mode, parent, value, &fops_ul);
162}
163
164#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
165DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
166 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
167
168static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
169 const char *name, mode_t mode,
170 struct dentry *parent, unsigned long *value)
171{
172 return debugfs_create_file(name, mode, parent, value,
173 &fops_ul_MAX_STACK_TRACE_DEPTH);
174}
175#endif
176
177static void debugfs_atomic_t_set(void *data, u64 val)
178{
179 atomic_set((atomic_t *)data, val);
180}
181
182static u64 debugfs_atomic_t_get(void *data)
183{
184 return atomic_read((atomic_t *)data);
185}
186
187DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
188 debugfs_atomic_t_set, "%lld\n");
189
190static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
191 struct dentry *parent, atomic_t *value)
192{
193 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
194}
195
196void cleanup_fault_attr_dentries(struct fault_attr *attr)
197{
198 debugfs_remove(attr->dentries.probability_file);
199 attr->dentries.probability_file = NULL;
200
201 debugfs_remove(attr->dentries.interval_file);
202 attr->dentries.interval_file = NULL;
203
204 debugfs_remove(attr->dentries.times_file);
205 attr->dentries.times_file = NULL;
206
207 debugfs_remove(attr->dentries.space_file);
208 attr->dentries.space_file = NULL;
209
210 debugfs_remove(attr->dentries.verbose_file);
211 attr->dentries.verbose_file = NULL;
212
213 debugfs_remove(attr->dentries.task_filter_file);
214 attr->dentries.task_filter_file = NULL;
215
216#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
217
218 debugfs_remove(attr->dentries.stacktrace_depth_file);
219 attr->dentries.stacktrace_depth_file = NULL;
220
221 debugfs_remove(attr->dentries.require_start_file);
222 attr->dentries.require_start_file = NULL;
223
224 debugfs_remove(attr->dentries.require_end_file);
225 attr->dentries.require_end_file = NULL;
226
227 debugfs_remove(attr->dentries.reject_start_file);
228 attr->dentries.reject_start_file = NULL;
229
230 debugfs_remove(attr->dentries.reject_end_file);
231 attr->dentries.reject_end_file = NULL;
232
233#endif
234
235 if (attr->dentries.dir)
236 WARN_ON(!simple_empty(attr->dentries.dir));
237
238 debugfs_remove(attr->dentries.dir);
239 attr->dentries.dir = NULL;
240}
241
242int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
243{
244 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
245 struct dentry *dir;
246
247 memset(&attr->dentries, 0, sizeof(attr->dentries));
248
249 dir = debugfs_create_dir(name, NULL);
250 if (!dir)
251 goto fail;
252 attr->dentries.dir = dir;
253
254 attr->dentries.probability_file =
255 debugfs_create_ul("probability", mode, dir, &attr->probability);
256
257 attr->dentries.interval_file =
258 debugfs_create_ul("interval", mode, dir, &attr->interval);
259
260 attr->dentries.times_file =
261 debugfs_create_atomic_t("times", mode, dir, &attr->times);
262
263 attr->dentries.space_file =
264 debugfs_create_atomic_t("space", mode, dir, &attr->space);
265
266 attr->dentries.verbose_file =
267 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
268
269 attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
270 mode, dir, &attr->task_filter);
271
272 if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
273 !attr->dentries.times_file || !attr->dentries.space_file ||
274 !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
275 goto fail;
276
277#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
278
279 attr->dentries.stacktrace_depth_file =
280 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
281 "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
282
283 attr->dentries.require_start_file =
284 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
285
286 attr->dentries.require_end_file =
287 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
288
289 attr->dentries.reject_start_file =
290 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
291
292 attr->dentries.reject_end_file =
293 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
294
295 if (!attr->dentries.stacktrace_depth_file ||
296 !attr->dentries.require_start_file ||
297 !attr->dentries.require_end_file ||
298 !attr->dentries.reject_start_file ||
299 !attr->dentries.reject_end_file)
300 goto fail;
301
302#endif
303
304 return 0;
305fail:
306 cleanup_fault_attr_dentries(attr);
307 return -ENOMEM;
308}
309
310#endif
311
