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/stacktrace.h> 10 #include <linux/kallsyms.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 __init 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 40 static void fail_dump(struct fault_attr *attr) 41 { 42 if (attr->verbose > 0) 43 printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n"); 44 if (attr->verbose > 1) 45 dump_stack(); 46 } 47 48 #define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0) 49 50 static bool fail_task(struct fault_attr *attr, struct task_struct *task) 51 { 52 return !in_interrupt() && task->make_it_fail; 53 } 54 55 #define MAX_STACK_TRACE_DEPTH 32 56 57 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 58 59 static bool fail_stacktrace(struct fault_attr *attr) 60 { 61 struct stack_trace trace; 62 int depth = attr->stacktrace_depth; 63 unsigned long entries[MAX_STACK_TRACE_DEPTH]; 64 int n; 65 bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX); 66 67 if (depth == 0) 68 return found; 69 70 trace.nr_entries = 0; 71 trace.entries = entries; 72 trace.max_entries = depth; 73 trace.skip = 1; 74 75 save_stack_trace(&trace); 76 for (n = 0; n < trace.nr_entries; n++) { 77 if (attr->reject_start <= entries[n] && 78 entries[n] < attr->reject_end) 79 return false; 80 if (attr->require_start <= entries[n] && 81 entries[n] < attr->require_end) 82 found = true; 83 } 84 return found; 85 } 86 87 #else 88 89 static inline bool fail_stacktrace(struct fault_attr *attr) 90 { 91 return true; 92 } 93 94 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 95 96 /* 97 * This code is stolen from failmalloc-1.0 98 * http://www.nongnu.org/failmalloc/ 99 */ 100 101 bool should_fail(struct fault_attr *attr, ssize_t size) 102 { 103 if (attr->task_filter && !fail_task(attr, current)) 104 return false; 105 106 if (atomic_read(&attr->times) == 0) 107 return false; 108 109 if (atomic_read(&attr->space) > size) { 110 atomic_sub(size, &attr->space); 111 return false; 112 } 113 114 if (attr->interval > 1) { 115 attr->count++; 116 if (attr->count % attr->interval) 117 return false; 118 } 119 120 if (attr->probability <= random32() % 100) 121 return false; 122 123 if (!fail_stacktrace(attr)) 124 return false; 125 126 fail_dump(attr); 127 128 if (atomic_read(&attr->times) != -1) 129 atomic_dec_not_zero(&attr->times); 130 131 return true; 132 } 133 134 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 135 136 static int debugfs_ul_set(void *data, u64 val) 137 { 138 *(unsigned long *)data = val; 139 return 0; 140 } 141 142 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 143 static int debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val) 144 { 145 *(unsigned long *)data = 146 val < MAX_STACK_TRACE_DEPTH ? 147 val : MAX_STACK_TRACE_DEPTH; 148 return 0; 149 } 150 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 151 152 static int debugfs_ul_get(void *data, u64 *val) 153 { 154 *val = *(unsigned long *)data; 155 return 0; 156 } 157 158 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 159 160 static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 161 struct dentry *parent, unsigned long *value) 162 { 163 return debugfs_create_file(name, mode, parent, value, &fops_ul); 164 } 165 166 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 167 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, 168 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); 169 170 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 171 const char *name, mode_t mode, 172 struct dentry *parent, unsigned long *value) 173 { 174 return debugfs_create_file(name, mode, parent, value, 175 &fops_ul_MAX_STACK_TRACE_DEPTH); 176 } 177 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 178 179 static int debugfs_atomic_t_set(void *data, u64 val) 180 { 181 atomic_set((atomic_t *)data, val); 182 return 0; 183 } 184 185 static int debugfs_atomic_t_get(void *data, u64 *val) 186 { 187 *val = atomic_read((atomic_t *)data); 188 return 0; 189 } 190 191 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, 192 debugfs_atomic_t_set, "%lld\n"); 193 194 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, 195 struct dentry *parent, atomic_t *value) 196 { 197 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); 198 } 199 200 void cleanup_fault_attr_dentries(struct fault_attr *attr) 201 { 202 debugfs_remove(attr->dentries.probability_file); 203 attr->dentries.probability_file = NULL; 204 205 debugfs_remove(attr->dentries.interval_file); 206 attr->dentries.interval_file = NULL; 207 208 debugfs_remove(attr->dentries.times_file); 209 attr->dentries.times_file = NULL; 210 211 debugfs_remove(attr->dentries.space_file); 212 attr->dentries.space_file = NULL; 213 214 debugfs_remove(attr->dentries.verbose_file); 215 attr->dentries.verbose_file = NULL; 216 217 debugfs_remove(attr->dentries.task_filter_file); 218 attr->dentries.task_filter_file = NULL; 219 220 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 221 222 debugfs_remove(attr->dentries.stacktrace_depth_file); 223 attr->dentries.stacktrace_depth_file = NULL; 224 225 debugfs_remove(attr->dentries.require_start_file); 226 attr->dentries.require_start_file = NULL; 227 228 debugfs_remove(attr->dentries.require_end_file); 229 attr->dentries.require_end_file = NULL; 230 231 debugfs_remove(attr->dentries.reject_start_file); 232 attr->dentries.reject_start_file = NULL; 233 234 debugfs_remove(attr->dentries.reject_end_file); 235 attr->dentries.reject_end_file = NULL; 236 237 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 238 239 if (attr->dentries.dir) 240 WARN_ON(!simple_empty(attr->dentries.dir)); 241 242 debugfs_remove(attr->dentries.dir); 243 attr->dentries.dir = NULL; 244 } 245 246 int init_fault_attr_dentries(struct fault_attr *attr, const char *name) 247 { 248 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 249 struct dentry *dir; 250 251 memset(&attr->dentries, 0, sizeof(attr->dentries)); 252 253 dir = debugfs_create_dir(name, NULL); 254 if (!dir) 255 goto fail; 256 attr->dentries.dir = dir; 257 258 attr->dentries.probability_file = 259 debugfs_create_ul("probability", mode, dir, &attr->probability); 260 261 attr->dentries.interval_file = 262 debugfs_create_ul("interval", mode, dir, &attr->interval); 263 264 attr->dentries.times_file = 265 debugfs_create_atomic_t("times", mode, dir, &attr->times); 266 267 attr->dentries.space_file = 268 debugfs_create_atomic_t("space", mode, dir, &attr->space); 269 270 attr->dentries.verbose_file = 271 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 272 273 attr->dentries.task_filter_file = debugfs_create_bool("task-filter", 274 mode, dir, &attr->task_filter); 275 276 if (!attr->dentries.probability_file || !attr->dentries.interval_file || 277 !attr->dentries.times_file || !attr->dentries.space_file || 278 !attr->dentries.verbose_file || !attr->dentries.task_filter_file) 279 goto fail; 280 281 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 282 283 attr->dentries.stacktrace_depth_file = 284 debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 285 "stacktrace-depth", mode, dir, &attr->stacktrace_depth); 286 287 attr->dentries.require_start_file = 288 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 289 290 attr->dentries.require_end_file = 291 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 292 293 attr->dentries.reject_start_file = 294 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 295 296 attr->dentries.reject_end_file = 297 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 298 299 if (!attr->dentries.stacktrace_depth_file || 300 !attr->dentries.require_start_file || 301 !attr->dentries.require_end_file || 302 !attr->dentries.reject_start_file || 303 !attr->dentries.reject_end_file) 304 goto fail; 305 306 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 307 308 return 0; 309 fail: 310 cleanup_fault_attr_dentries(attr); 311 return -ENOMEM; 312 } 313 314 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 315