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/unwind.h> 10 #include <linux/stacktrace.h> 11 #include <linux/kallsyms.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 __init 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, ×) < 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 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 } 134 135 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 136 137 static void debugfs_ul_set(void *data, u64 val) 138 { 139 *(unsigned long *)data = val; 140 } 141 142 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 143 static void 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 } 149 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 150 151 static u64 debugfs_ul_get(void *data) 152 { 153 return *(unsigned long *)data; 154 } 155 156 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 157 158 static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 159 struct dentry *parent, unsigned long *value) 160 { 161 return debugfs_create_file(name, mode, parent, value, &fops_ul); 162 } 163 164 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 165 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, 166 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); 167 168 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 169 const char *name, mode_t mode, 170 struct dentry *parent, unsigned long *value) 171 { 172 return debugfs_create_file(name, mode, parent, value, 173 &fops_ul_MAX_STACK_TRACE_DEPTH); 174 } 175 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 176 177 static void debugfs_atomic_t_set(void *data, u64 val) 178 { 179 atomic_set((atomic_t *)data, val); 180 } 181 182 static u64 debugfs_atomic_t_get(void *data) 183 { 184 return atomic_read((atomic_t *)data); 185 } 186 187 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, 188 debugfs_atomic_t_set, "%lld\n"); 189 190 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, 191 struct dentry *parent, atomic_t *value) 192 { 193 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); 194 } 195 196 void cleanup_fault_attr_dentries(struct fault_attr *attr) 197 { 198 debugfs_remove(attr->dentries.probability_file); 199 attr->dentries.probability_file = NULL; 200 201 debugfs_remove(attr->dentries.interval_file); 202 attr->dentries.interval_file = NULL; 203 204 debugfs_remove(attr->dentries.times_file); 205 attr->dentries.times_file = NULL; 206 207 debugfs_remove(attr->dentries.space_file); 208 attr->dentries.space_file = NULL; 209 210 debugfs_remove(attr->dentries.verbose_file); 211 attr->dentries.verbose_file = NULL; 212 213 debugfs_remove(attr->dentries.task_filter_file); 214 attr->dentries.task_filter_file = NULL; 215 216 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 217 218 debugfs_remove(attr->dentries.stacktrace_depth_file); 219 attr->dentries.stacktrace_depth_file = NULL; 220 221 debugfs_remove(attr->dentries.require_start_file); 222 attr->dentries.require_start_file = NULL; 223 224 debugfs_remove(attr->dentries.require_end_file); 225 attr->dentries.require_end_file = NULL; 226 227 debugfs_remove(attr->dentries.reject_start_file); 228 attr->dentries.reject_start_file = NULL; 229 230 debugfs_remove(attr->dentries.reject_end_file); 231 attr->dentries.reject_end_file = NULL; 232 233 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 234 235 if (attr->dentries.dir) 236 WARN_ON(!simple_empty(attr->dentries.dir)); 237 238 debugfs_remove(attr->dentries.dir); 239 attr->dentries.dir = NULL; 240 } 241 242 int init_fault_attr_dentries(struct fault_attr *attr, const char *name) 243 { 244 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 245 struct dentry *dir; 246 247 memset(&attr->dentries, 0, sizeof(attr->dentries)); 248 249 dir = debugfs_create_dir(name, NULL); 250 if (!dir) 251 goto fail; 252 attr->dentries.dir = dir; 253 254 attr->dentries.probability_file = 255 debugfs_create_ul("probability", mode, dir, &attr->probability); 256 257 attr->dentries.interval_file = 258 debugfs_create_ul("interval", mode, dir, &attr->interval); 259 260 attr->dentries.times_file = 261 debugfs_create_atomic_t("times", mode, dir, &attr->times); 262 263 attr->dentries.space_file = 264 debugfs_create_atomic_t("space", mode, dir, &attr->space); 265 266 attr->dentries.verbose_file = 267 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 268 269 attr->dentries.task_filter_file = debugfs_create_bool("task-filter", 270 mode, dir, &attr->task_filter); 271 272 if (!attr->dentries.probability_file || !attr->dentries.interval_file || 273 !attr->dentries.times_file || !attr->dentries.space_file || 274 !attr->dentries.verbose_file || !attr->dentries.task_filter_file) 275 goto fail; 276 277 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 278 279 attr->dentries.stacktrace_depth_file = 280 debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 281 "stacktrace-depth", mode, dir, &attr->stacktrace_depth); 282 283 attr->dentries.require_start_file = 284 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 285 286 attr->dentries.require_end_file = 287 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 288 289 attr->dentries.reject_start_file = 290 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 291 292 attr->dentries.reject_end_file = 293 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 294 295 if (!attr->dentries.stacktrace_depth_file || 296 !attr->dentries.require_start_file || 297 !attr->dentries.require_end_file || 298 !attr->dentries.reject_start_file || 299 !attr->dentries.reject_end_file) 300 goto fail; 301 302 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 303 304 return 0; 305 fail: 306 cleanup_fault_attr_dentries(attr); 307 return -ENOMEM; 308 } 309 310 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 311