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/fault-inject.h> 12 13 /* 14 * setup_fault_attr() is a helper function for various __setup handlers, so it 15 * returns 0 on error, because that is what __setup handlers do. 16 */ 17 int setup_fault_attr(struct fault_attr *attr, char *str) 18 { 19 unsigned long probability; 20 unsigned long interval; 21 int times; 22 int space; 23 24 /* "<interval>,<probability>,<space>,<times>" */ 25 if (sscanf(str, "%lu,%lu,%d,%d", 26 &interval, &probability, &space, ×) < 4) { 27 printk(KERN_WARNING 28 "FAULT_INJECTION: failed to parse arguments\n"); 29 return 0; 30 } 31 32 attr->probability = probability; 33 attr->interval = interval; 34 atomic_set(&attr->times, times); 35 atomic_set(&attr->space, space); 36 37 return 1; 38 } 39 EXPORT_SYMBOL_GPL(setup_fault_attr); 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 EXPORT_SYMBOL_GPL(should_fail); 135 136 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 137 138 static int debugfs_ul_set(void *data, u64 val) 139 { 140 *(unsigned long *)data = val; 141 return 0; 142 } 143 144 static int debugfs_ul_get(void *data, u64 *val) 145 { 146 *val = *(unsigned long *)data; 147 return 0; 148 } 149 150 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 151 152 static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 153 struct dentry *parent, unsigned long *value) 154 { 155 return debugfs_create_file(name, mode, parent, value, &fops_ul); 156 } 157 158 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 159 160 static int debugfs_stacktrace_depth_set(void *data, u64 val) 161 { 162 *(unsigned long *)data = 163 min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); 164 165 return 0; 166 } 167 168 DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, 169 debugfs_stacktrace_depth_set, "%llu\n"); 170 171 static struct dentry *debugfs_create_stacktrace_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_stacktrace_depth); 177 } 178 179 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 180 181 static int debugfs_atomic_t_set(void *data, u64 val) 182 { 183 atomic_set((atomic_t *)data, val); 184 return 0; 185 } 186 187 static int debugfs_atomic_t_get(void *data, u64 *val) 188 { 189 *val = atomic_read((atomic_t *)data); 190 return 0; 191 } 192 193 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, 194 debugfs_atomic_t_set, "%lld\n"); 195 196 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, 197 struct dentry *parent, atomic_t *value) 198 { 199 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); 200 } 201 202 struct dentry *fault_create_debugfs_attr(const char *name, 203 struct dentry *parent, struct fault_attr *attr) 204 { 205 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 206 struct dentry *dir; 207 208 dir = debugfs_create_dir(name, parent); 209 if (!dir) 210 return ERR_PTR(-ENOMEM); 211 212 if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) 213 goto fail; 214 if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) 215 goto fail; 216 if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) 217 goto fail; 218 if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) 219 goto fail; 220 if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) 221 goto fail; 222 if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) 223 goto fail; 224 225 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 226 227 if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, 228 &attr->stacktrace_depth)) 229 goto fail; 230 if (!debugfs_create_ul("require-start", mode, dir, 231 &attr->require_start)) 232 goto fail; 233 if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) 234 goto fail; 235 if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) 236 goto fail; 237 if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) 238 goto fail; 239 240 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 241 242 return dir; 243 fail: 244 debugfs_remove_recursive(dir); 245 246 return ERR_PTR(-ENOMEM); 247 } 248 EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); 249 250 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 251