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>
9 #include <linux/export.h>
10 #include <linux/interrupt.h>
11 #include <linux/stacktrace.h>
12 #include <linux/fault-inject.h>
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.
18 int setup_fault_attr(struct fault_attr *attr, char *str)
20 unsigned long probability;
21 unsigned long interval;
25 /* "<interval>,<probability>,<space>,<times>" */
26 if (sscanf(str, "%lu,%lu,%d,%d",
27 &interval, &probability, &space, ×) < 4) {
29 "FAULT_INJECTION: failed to parse arguments\n");
33 attr->probability = probability;
34 attr->interval = interval;
35 atomic_set(&attr->times, times);
36 atomic_set(&attr->space, space);
40 EXPORT_SYMBOL_GPL(setup_fault_attr);
42 static void fail_dump(struct fault_attr *attr)
47 if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
48 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
49 "name %pd, interval %lu, probability %lu, "
50 "space %d, times %d\n", attr->dname,
51 attr->interval, attr->probability,
52 atomic_read(&attr->space),
53 atomic_read(&attr->times));
54 if (attr->verbose > 1)
59 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
61 static bool fail_task(struct fault_attr *attr, struct task_struct *task)
63 return in_task() && task->make_it_fail;
66 #define MAX_STACK_TRACE_DEPTH 32
68 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
70 static bool fail_stacktrace(struct fault_attr *attr)
72 int depth = attr->stacktrace_depth;
73 unsigned long entries[MAX_STACK_TRACE_DEPTH];
75 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
80 nr_entries = stack_trace_save(entries, depth, 1);
81 for (n = 0; n < nr_entries; n++) {
82 if (attr->reject_start <= entries[n] &&
83 entries[n] < attr->reject_end)
85 if (attr->require_start <= entries[n] &&
86 entries[n] < attr->require_end)
94 static inline bool fail_stacktrace(struct fault_attr *attr)
99 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
102 * This code is stolen from failmalloc-1.0
103 * http://www.nongnu.org/failmalloc/
106 bool should_fail(struct fault_attr *attr, ssize_t size)
109 unsigned int fail_nth = READ_ONCE(current->fail_nth);
113 WRITE_ONCE(current->fail_nth, fail_nth);
121 /* No need to check any other properties if the probability is 0 */
122 if (attr->probability == 0)
125 if (attr->task_filter && !fail_task(attr, current))
128 if (atomic_read(&attr->times) == 0)
131 if (atomic_read(&attr->space) > size) {
132 atomic_sub(size, &attr->space);
136 if (attr->interval > 1) {
138 if (attr->count % attr->interval)
142 if (attr->probability <= prandom_u32() % 100)
145 if (!fail_stacktrace(attr))
151 if (atomic_read(&attr->times) != -1)
152 atomic_dec_not_zero(&attr->times);
156 EXPORT_SYMBOL_GPL(should_fail);
158 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
160 static int debugfs_ul_set(void *data, u64 val)
162 *(unsigned long *)data = val;
166 static int debugfs_ul_get(void *data, u64 *val)
168 *val = *(unsigned long *)data;
172 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
174 static void debugfs_create_ul(const char *name, umode_t mode,
175 struct dentry *parent, unsigned long *value)
177 debugfs_create_file(name, mode, parent, value, &fops_ul);
180 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
182 static int debugfs_stacktrace_depth_set(void *data, u64 val)
184 *(unsigned long *)data =
185 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
190 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
191 debugfs_stacktrace_depth_set, "%llu\n");
193 static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
194 struct dentry *parent,
195 unsigned long *value)
197 debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
200 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
202 struct dentry *fault_create_debugfs_attr(const char *name,
203 struct dentry *parent, struct fault_attr *attr)
205 umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
208 dir = debugfs_create_dir(name, parent);
212 debugfs_create_ul("probability", mode, dir, &attr->probability);
213 debugfs_create_ul("interval", mode, dir, &attr->interval);
214 debugfs_create_atomic_t("times", mode, dir, &attr->times);
215 debugfs_create_atomic_t("space", mode, dir, &attr->space);
216 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
217 debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
218 &attr->ratelimit_state.interval);
219 debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
220 &attr->ratelimit_state.burst);
221 debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
223 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
224 debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
225 &attr->stacktrace_depth);
226 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
227 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
228 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
229 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
232 attr->dname = dget(dir);
235 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
237 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */