Merge tag 'ras_core_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-block.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 || (found && !attr->reject_start && !attr->reject_end))
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_ex(struct fault_attr *attr, ssize_t size, int flags)
104 {
105         bool stack_checked = false;
106
107         if (in_task()) {
108                 unsigned int fail_nth = READ_ONCE(current->fail_nth);
109
110                 if (fail_nth) {
111                         if (!fail_stacktrace(attr))
112                                 return false;
113
114                         stack_checked = true;
115                         fail_nth--;
116                         WRITE_ONCE(current->fail_nth, fail_nth);
117                         if (!fail_nth)
118                                 goto fail;
119
120                         return false;
121                 }
122         }
123
124         /* No need to check any other properties if the probability is 0 */
125         if (attr->probability == 0)
126                 return false;
127
128         if (attr->task_filter && !fail_task(attr, current))
129                 return false;
130
131         if (atomic_read(&attr->times) == 0)
132                 return false;
133
134         if (!stack_checked && !fail_stacktrace(attr))
135                 return false;
136
137         if (atomic_read(&attr->space) > size) {
138                 atomic_sub(size, &attr->space);
139                 return false;
140         }
141
142         if (attr->interval > 1) {
143                 attr->count++;
144                 if (attr->count % attr->interval)
145                         return false;
146         }
147
148         if (attr->probability <= get_random_u32_below(100))
149                 return false;
150
151 fail:
152         if (!(flags & FAULT_NOWARN))
153                 fail_dump(attr);
154
155         if (atomic_read(&attr->times) != -1)
156                 atomic_dec_not_zero(&attr->times);
157
158         return true;
159 }
160
161 bool should_fail(struct fault_attr *attr, ssize_t size)
162 {
163         return should_fail_ex(attr, size, 0);
164 }
165 EXPORT_SYMBOL_GPL(should_fail);
166
167 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
168
169 static int debugfs_ul_set(void *data, u64 val)
170 {
171         *(unsigned long *)data = val;
172         return 0;
173 }
174
175 static int debugfs_ul_get(void *data, u64 *val)
176 {
177         *val = *(unsigned long *)data;
178         return 0;
179 }
180
181 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
182
183 static void debugfs_create_ul(const char *name, umode_t mode,
184                               struct dentry *parent, unsigned long *value)
185 {
186         debugfs_create_file(name, mode, parent, value, &fops_ul);
187 }
188
189 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
190
191 static int debugfs_stacktrace_depth_set(void *data, u64 val)
192 {
193         *(unsigned long *)data =
194                 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
195
196         return 0;
197 }
198
199 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
200                         debugfs_stacktrace_depth_set, "%llu\n");
201
202 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
203                                             struct dentry *parent,
204                                             unsigned long *value)
205 {
206         debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
207 }
208
209 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
210
211 struct dentry *fault_create_debugfs_attr(const char *name,
212                         struct dentry *parent, struct fault_attr *attr)
213 {
214         umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
215         struct dentry *dir;
216
217         dir = debugfs_create_dir(name, parent);
218         if (IS_ERR(dir))
219                 return dir;
220
221         debugfs_create_ul("probability", mode, dir, &attr->probability);
222         debugfs_create_ul("interval", mode, dir, &attr->interval);
223         debugfs_create_atomic_t("times", mode, dir, &attr->times);
224         debugfs_create_atomic_t("space", mode, dir, &attr->space);
225         debugfs_create_ul("verbose", mode, dir, &attr->verbose);
226         debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
227                            &attr->ratelimit_state.interval);
228         debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
229                            &attr->ratelimit_state.burst);
230         debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
231
232 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
233         debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
234                                         &attr->stacktrace_depth);
235         debugfs_create_xul("require-start", mode, dir, &attr->require_start);
236         debugfs_create_xul("require-end", mode, dir, &attr->require_end);
237         debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
238         debugfs_create_xul("reject-end", mode, dir, &attr->reject_end);
239 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
240
241         attr->dname = dget(dir);
242         return dir;
243 }
244 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
245
246 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */