perf tools: Enable libtraceevent dynamic linking
[linux-2.6-microblaze.git] / lib / fault-inject.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/init.h>
4 #include <linux/random.h>
5 #include <linux/sched.h>
6 #include <linux/stat.h>
7 #include <linux/types.h>
8 #include <linux/fs.h>
9 #include <linux/export.h>
10 #include <linux/interrupt.h>
11 #include <linux/stacktrace.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 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 EXPORT_SYMBOL_GPL(setup_fault_attr);
41
42 static void fail_dump(struct fault_attr *attr)
43 {
44         if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
45                 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
46                        "name %pd, interval %lu, probability %lu, "
47                        "space %d, times %d\n", attr->dname,
48                        attr->interval, attr->probability,
49                        atomic_read(&attr->space),
50                        atomic_read(&attr->times));
51                 if (attr->verbose > 1)
52                         dump_stack();
53         }
54 }
55
56 #define atomic_dec_not_zero(v)          atomic_add_unless((v), -1, 0)
57
58 static bool fail_task(struct fault_attr *attr, struct task_struct *task)
59 {
60         return in_task() && task->make_it_fail;
61 }
62
63 #define MAX_STACK_TRACE_DEPTH 32
64
65 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
66
67 static bool fail_stacktrace(struct fault_attr *attr)
68 {
69         int depth = attr->stacktrace_depth;
70         unsigned long entries[MAX_STACK_TRACE_DEPTH];
71         int n, nr_entries;
72         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
73
74         if (depth == 0)
75                 return found;
76
77         nr_entries = stack_trace_save(entries, depth, 1);
78         for (n = 0; n < nr_entries; n++) {
79                 if (attr->reject_start <= entries[n] &&
80                                entries[n] < attr->reject_end)
81                         return false;
82                 if (attr->require_start <= entries[n] &&
83                                entries[n] < attr->require_end)
84                         found = true;
85         }
86         return found;
87 }
88
89 #else
90
91 static inline bool fail_stacktrace(struct fault_attr *attr)
92 {
93         return true;
94 }
95
96 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
97
98 /*
99  * This code is stolen from failmalloc-1.0
100  * http://www.nongnu.org/failmalloc/
101  */
102
103 bool should_fail(struct fault_attr *attr, ssize_t size)
104 {
105         if (in_task()) {
106                 unsigned int fail_nth = READ_ONCE(current->fail_nth);
107
108                 if (fail_nth) {
109                         fail_nth--;
110                         WRITE_ONCE(current->fail_nth, fail_nth);
111                         if (!fail_nth)
112                                 goto fail;
113
114                         return false;
115                 }
116         }
117
118         /* No need to check any other properties if the probability is 0 */
119         if (attr->probability == 0)
120                 return false;
121
122         if (attr->task_filter && !fail_task(attr, current))
123                 return false;
124
125         if (atomic_read(&attr->times) == 0)
126                 return false;
127
128         if (atomic_read(&attr->space) > size) {
129                 atomic_sub(size, &attr->space);
130                 return false;
131         }
132
133         if (attr->interval > 1) {
134                 attr->count++;
135                 if (attr->count % attr->interval)
136                         return false;
137         }
138
139         if (attr->probability <= prandom_u32() % 100)
140                 return false;
141
142         if (!fail_stacktrace(attr))
143                 return false;
144
145 fail:
146         fail_dump(attr);
147
148         if (atomic_read(&attr->times) != -1)
149                 atomic_dec_not_zero(&attr->times);
150
151         return true;
152 }
153 EXPORT_SYMBOL_GPL(should_fail);
154
155 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
156
157 static int debugfs_ul_set(void *data, u64 val)
158 {
159         *(unsigned long *)data = val;
160         return 0;
161 }
162
163 static int debugfs_ul_get(void *data, u64 *val)
164 {
165         *val = *(unsigned long *)data;
166         return 0;
167 }
168
169 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
170
171 static void debugfs_create_ul(const char *name, umode_t mode,
172                               struct dentry *parent, unsigned long *value)
173 {
174         debugfs_create_file(name, mode, parent, value, &fops_ul);
175 }
176
177 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
178
179 static int debugfs_stacktrace_depth_set(void *data, u64 val)
180 {
181         *(unsigned long *)data =
182                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
183
184         return 0;
185 }
186
187 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
188                         debugfs_stacktrace_depth_set, "%llu\n");
189
190 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
191                                             struct dentry *parent,
192                                             unsigned long *value)
193 {
194         debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
195 }
196
197 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
198
199 struct dentry *fault_create_debugfs_attr(const char *name,
200                         struct dentry *parent, struct fault_attr *attr)
201 {
202         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
203         struct dentry *dir;
204
205         dir = debugfs_create_dir(name, parent);
206         if (IS_ERR(dir))
207                 return dir;
208
209         debugfs_create_ul("probability", mode, dir, &attr->probability);
210         debugfs_create_ul("interval", mode, dir, &attr->interval);
211         debugfs_create_atomic_t("times", mode, dir, &attr->times);
212         debugfs_create_atomic_t("space", mode, dir, &attr->space);
213         debugfs_create_ul("verbose", mode, dir, &attr->verbose);
214         debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
215                            &attr->ratelimit_state.interval);
216         debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
217                            &attr->ratelimit_state.burst);
218         debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
219
220 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
221         debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
222                                         &attr->stacktrace_depth);
223         debugfs_create_ul("require-start", mode, dir, &attr->require_start);
224         debugfs_create_ul("require-end", mode, dir, &attr->require_end);
225         debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
226         debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
227 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
228
229         attr->dname = dget(dir);
230         return dir;
231 }
232 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
233
234 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */