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 */
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	/* "<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
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 /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
96
97/*
98 * This code is stolen from failmalloc-1.0
99 * http://www.nongnu.org/failmalloc/
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
142static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
143{
144	*(unsigned long *)data =
145		val < MAX_STACK_TRACE_DEPTH ?
146		val : MAX_STACK_TRACE_DEPTH;
147}
148
149static u64 debugfs_ul_get(void *data)
150{
151	return *(unsigned long *)data;
152}
153
154DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
155
156static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
157				struct dentry *parent, unsigned long *value)
158{
159	return debugfs_create_file(name, mode, parent, value, &fops_ul);
160}
161
162DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
163			debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
164
165static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
166	const char *name, mode_t mode,
167	struct dentry *parent, unsigned long *value)
168{
169	return debugfs_create_file(name, mode, parent, value,
170				   &fops_ul_MAX_STACK_TRACE_DEPTH);
171}
172
173static void debugfs_atomic_t_set(void *data, u64 val)
174{
175	atomic_set((atomic_t *)data, val);
176}
177
178static u64 debugfs_atomic_t_get(void *data)
179{
180	return atomic_read((atomic_t *)data);
181}
182
183DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
184			debugfs_atomic_t_set, "%lld\n");
185
186static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
187				struct dentry *parent, atomic_t *value)
188{
189	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
190}
191
192void cleanup_fault_attr_dentries(struct fault_attr *attr)
193{
194	debugfs_remove(attr->dentries.probability_file);
195	attr->dentries.probability_file = NULL;
196
197	debugfs_remove(attr->dentries.interval_file);
198	attr->dentries.interval_file = NULL;
199
200	debugfs_remove(attr->dentries.times_file);
201	attr->dentries.times_file = NULL;
202
203	debugfs_remove(attr->dentries.space_file);
204	attr->dentries.space_file = NULL;
205
206	debugfs_remove(attr->dentries.verbose_file);
207	attr->dentries.verbose_file = NULL;
208
209	debugfs_remove(attr->dentries.task_filter_file);
210	attr->dentries.task_filter_file = NULL;
211
212#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
213
214	debugfs_remove(attr->dentries.stacktrace_depth_file);
215	attr->dentries.stacktrace_depth_file = NULL;
216
217	debugfs_remove(attr->dentries.require_start_file);
218	attr->dentries.require_start_file = NULL;
219
220	debugfs_remove(attr->dentries.require_end_file);
221	attr->dentries.require_end_file = NULL;
222
223	debugfs_remove(attr->dentries.reject_start_file);
224	attr->dentries.reject_start_file = NULL;
225
226	debugfs_remove(attr->dentries.reject_end_file);
227	attr->dentries.reject_end_file = NULL;
228
229#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
230
231	if (attr->dentries.dir)
232		WARN_ON(!simple_empty(attr->dentries.dir));
233
234	debugfs_remove(attr->dentries.dir);
235	attr->dentries.dir = NULL;
236}
237
238int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
239{
240	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
241	struct dentry *dir;
242
243	memset(&attr->dentries, 0, sizeof(attr->dentries));
244
245	dir = debugfs_create_dir(name, NULL);
246	if (!dir)
247		goto fail;
248	attr->dentries.dir = dir;
249
250	attr->dentries.probability_file =
251		debugfs_create_ul("probability", mode, dir, &attr->probability);
252
253	attr->dentries.interval_file =
254		debugfs_create_ul("interval", mode, dir, &attr->interval);
255
256	attr->dentries.times_file =
257		debugfs_create_atomic_t("times", mode, dir, &attr->times);
258
259	attr->dentries.space_file =
260		debugfs_create_atomic_t("space", mode, dir, &attr->space);
261
262	attr->dentries.verbose_file =
263		debugfs_create_ul("verbose", mode, dir, &attr->verbose);
264
265	attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
266						mode, dir, &attr->task_filter);
267
268	if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
269	    !attr->dentries.times_file || !attr->dentries.space_file ||
270	    !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
271		goto fail;
272
273#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
274
275	attr->dentries.stacktrace_depth_file =
276		debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
277			"stacktrace-depth", mode, dir, &attr->stacktrace_depth);
278
279	attr->dentries.require_start_file =
280		debugfs_create_ul("require-start", mode, dir, &attr->require_start);
281
282	attr->dentries.require_end_file =
283		debugfs_create_ul("require-end", mode, dir, &attr->require_end);
284
285	attr->dentries.reject_start_file =
286		debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
287
288	attr->dentries.reject_end_file =
289		debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
290
291	if (!attr->dentries.stacktrace_depth_file ||
292	    !attr->dentries.require_start_file ||
293	    !attr->dentries.require_end_file ||
294	    !attr->dentries.reject_start_file ||
295	    !attr->dentries.reject_end_file)
296		goto fail;
297
298#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
299
300	return 0;
301fail:
302	cleanup_fault_attr_dentries(attr);
303	return -ENOMEM;
304}
305
306#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
307