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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/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 | * 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, ×) < 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_FAULT_INJECTION_STACKTRACE_FILTER |
59 | |
60 | static 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 | |
90 | static inline bool fail_stacktrace(struct fault_attr *attr) |
91 | { |
92 | return true; |
93 | } |
94 | |
95 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
96 | |
97 | /* |
98 | * This code is stolen from failmalloc-1.0 |
99 | * http://www.nongnu.org/failmalloc/ |
100 | */ |
101 | |
102 | bool 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 | |
137 | static 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 |
144 | static 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 /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
152 | |
153 | static int debugfs_ul_get(void *data, u64 *val) |
154 | { |
155 | *val = *(unsigned long *)data; |
156 | return 0; |
157 | } |
158 | |
159 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); |
160 | |
161 | static 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 |
168 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, |
169 | debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); |
170 | |
171 | static 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 /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
179 | |
180 | static int debugfs_atomic_t_set(void *data, u64 val) |
181 | { |
182 | atomic_set((atomic_t *)data, val); |
183 | return 0; |
184 | } |
185 | |
186 | static int debugfs_atomic_t_get(void *data, u64 *val) |
187 | { |
188 | *val = atomic_read((atomic_t *)data); |
189 | return 0; |
190 | } |
191 | |
192 | DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, |
193 | debugfs_atomic_t_set, "%lld\n"); |
194 | |
195 | static 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 | |
201 | void 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 /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
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 | |
247 | int 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 /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
308 | |
309 | return 0; |
310 | fail: |
311 | cleanup_fault_attr_dentries(attr); |
312 | return -ENOMEM; |
313 | } |
314 | |
315 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |
316 |
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