[PATCH] fault-injection: Clamp debugfs stacktrace-depth to MAX_STACK_TRACE_DEPTH
[linux-2.6.git] / lib / fault-inject.c
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  * setup_fault_attr() is a helper function for various __setup handlers, so it
16  * returns 0 on error, because that is what __setup handlers do.
17  */
18 int __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         /* "<interval>,<probability>,<space>,<times>" */
26         if (sscanf(str, "%lu,%lu,%d,%d",
27                         &interval, &probability, &space, &times) < 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
41 static 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
51 static 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_STACK_UNWIND
59
60 static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
61                                                 void *arg)
62 {
63         int depth;
64         struct fault_attr *attr = arg;
65         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
66
67         for (depth = 0; depth < attr->stacktrace_depth
68                         && unwind(info) == 0 && UNW_PC(info); depth++) {
69                 if (arch_unw_user_mode(info))
70                         break;
71                 if (attr->reject_start <= UNW_PC(info) &&
72                                UNW_PC(info) < attr->reject_end)
73                         return false;
74                 if (attr->require_start <= UNW_PC(info) &&
75                                UNW_PC(info) < attr->require_end)
76                         found = true;
77         }
78         return found;
79 }
80
81 static bool fail_stacktrace(struct fault_attr *attr)
82 {
83         struct unwind_frame_info info;
84
85         return unwind_init_running(&info, fail_stacktrace_callback, attr);
86 }
87
88 #elif defined(CONFIG_STACKTRACE)
89
90 static bool fail_stacktrace(struct fault_attr *attr)
91 {
92         struct stack_trace trace;
93         int depth = attr->stacktrace_depth;
94         unsigned long entries[MAX_STACK_TRACE_DEPTH];
95         int n;
96         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
97
98         if (depth == 0)
99                 return found;
100
101         trace.nr_entries = 0;
102         trace.entries = entries;
103         trace.max_entries = depth;
104         trace.skip = 1;
105         trace.all_contexts = 0;
106
107         save_stack_trace(&trace, NULL);
108         for (n = 0; n < trace.nr_entries; n++) {
109                 if (attr->reject_start <= entries[n] &&
110                                entries[n] < attr->reject_end)
111                         return false;
112                 if (attr->require_start <= entries[n] &&
113                                entries[n] < attr->require_end)
114                         found = true;
115         }
116         return found;
117 }
118
119 #else
120
121 static inline bool fail_stacktrace(struct fault_attr *attr)
122 {
123         static bool firsttime = true;
124
125         if (firsttime) {
126                 printk(KERN_WARNING
127                 "This architecture does not implement save_stack_trace()\n");
128                 firsttime = false;
129         }
130         return false;
131 }
132
133 #endif
134
135 /*
136  * This code is stolen from failmalloc-1.0
137  * http://www.nongnu.org/failmalloc/
138  */
139
140 bool should_fail(struct fault_attr *attr, ssize_t size)
141 {
142         if (attr->task_filter && !fail_task(attr, current))
143                 return false;
144
145         if (!fail_stacktrace(attr))
146                 return false;
147
148         if (atomic_read(&attr->times) == 0)
149                 return false;
150
151         if (atomic_read(&attr->space) > size) {
152                 atomic_sub(size, &attr->space);
153                 return false;
154         }
155
156         if (attr->interval > 1) {
157                 attr->count++;
158                 if (attr->count % attr->interval)
159                         return false;
160         }
161
162         if (attr->probability > random32() % 100)
163                 goto fail;
164
165         return false;
166
167 fail:
168         fail_dump(attr);
169
170         if (atomic_read(&attr->times) != -1)
171                 atomic_dec_not_zero(&attr->times);
172
173         return true;
174 }
175
176 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
177
178 static void debugfs_ul_set(void *data, u64 val)
179 {
180         *(unsigned long *)data = val;
181 }
182
183 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
184 {
185         *(unsigned long *)data =
186                 val < MAX_STACK_TRACE_DEPTH ?
187                 val : MAX_STACK_TRACE_DEPTH;
188 }
189
190 static u64 debugfs_ul_get(void *data)
191 {
192         return *(unsigned long *)data;
193 }
194
195 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
196
197 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
198                                 struct dentry *parent, unsigned long *value)
199 {
200         return debugfs_create_file(name, mode, parent, value, &fops_ul);
201 }
202
203 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
204                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
205
206 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
207         const char *name, mode_t mode,
208         struct dentry *parent, unsigned long *value)
209 {
210         return debugfs_create_file(name, mode, parent, value,
211                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
212 }
213
214 static void debugfs_atomic_t_set(void *data, u64 val)
215 {
216         atomic_set((atomic_t *)data, val);
217 }
218
219 static u64 debugfs_atomic_t_get(void *data)
220 {
221         return atomic_read((atomic_t *)data);
222 }
223
224 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
225                         debugfs_atomic_t_set, "%lld\n");
226
227 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
228                                 struct dentry *parent, atomic_t *value)
229 {
230         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
231 }
232
233 void cleanup_fault_attr_dentries(struct fault_attr *attr)
234 {
235         debugfs_remove(attr->dentries.probability_file);
236         attr->dentries.probability_file = NULL;
237
238         debugfs_remove(attr->dentries.interval_file);
239         attr->dentries.interval_file = NULL;
240
241         debugfs_remove(attr->dentries.times_file);
242         attr->dentries.times_file = NULL;
243
244         debugfs_remove(attr->dentries.space_file);
245         attr->dentries.space_file = NULL;
246
247         debugfs_remove(attr->dentries.verbose_file);
248         attr->dentries.verbose_file = NULL;
249
250         debugfs_remove(attr->dentries.task_filter_file);
251         attr->dentries.task_filter_file = NULL;
252
253         debugfs_remove(attr->dentries.stacktrace_depth_file);
254         attr->dentries.stacktrace_depth_file = NULL;
255
256         debugfs_remove(attr->dentries.require_start_file);
257         attr->dentries.require_start_file = NULL;
258
259         debugfs_remove(attr->dentries.require_end_file);
260         attr->dentries.require_end_file = NULL;
261
262         debugfs_remove(attr->dentries.reject_start_file);
263         attr->dentries.reject_start_file = NULL;
264
265         debugfs_remove(attr->dentries.reject_end_file);
266         attr->dentries.reject_end_file = NULL;
267
268         if (attr->dentries.dir)
269                 WARN_ON(!simple_empty(attr->dentries.dir));
270
271         debugfs_remove(attr->dentries.dir);
272         attr->dentries.dir = NULL;
273 }
274
275 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
276 {
277         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
278         struct dentry *dir;
279
280         memset(&attr->dentries, 0, sizeof(attr->dentries));
281
282         dir = debugfs_create_dir(name, NULL);
283         if (!dir)
284                 goto fail;
285         attr->dentries.dir = dir;
286
287         attr->dentries.probability_file =
288                 debugfs_create_ul("probability", mode, dir, &attr->probability);
289
290         attr->dentries.interval_file =
291                 debugfs_create_ul("interval", mode, dir, &attr->interval);
292
293         attr->dentries.times_file =
294                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
295
296         attr->dentries.space_file =
297                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
298
299         attr->dentries.verbose_file =
300                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
301
302         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
303                                                 mode, dir, &attr->task_filter);
304
305         attr->dentries.stacktrace_depth_file =
306                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
307                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
308
309         attr->dentries.require_start_file =
310                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
311
312         attr->dentries.require_end_file =
313                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
314
315         attr->dentries.reject_start_file =
316                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
317
318         attr->dentries.reject_end_file =
319                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
320
321
322         if (!attr->dentries.probability_file || !attr->dentries.interval_file
323             || !attr->dentries.times_file || !attr->dentries.space_file
324             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
325             || !attr->dentries.stacktrace_depth_file
326             || !attr->dentries.require_start_file
327             || !attr->dentries.require_end_file
328             || !attr->dentries.reject_start_file
329             || !attr->dentries.reject_end_file
330             )
331                 goto fail;
332
333         return 0;
334 fail:
335         cleanup_fault_attr_dentries(attr);
336         return -ENOMEM;
337 }
338
339 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */