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 trace.all_contexts = 0; 76 77 save_stack_trace(&trace, NULL); 78 for (n = 0; n < trace.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(struct fault_attr *attr, ssize_t size) 104 { 105 if (attr->task_filter && !fail_task(attr, current)) 106 return false; 107 108 if (atomic_read(&attr->times) == 0) 109 return false; 110 111 if (atomic_read(&attr->space) > size) { 112 atomic_sub(size, &attr->space); 113 return false; 114 } 115 116 if (attr->interval > 1) { 117 attr->count++; 118 if (attr->count % attr->interval) 119 return false; 120 } 121 122 if (attr->probability <= random32() % 100) 123 return false; 124 125 if (!fail_stacktrace(attr)) 126 return false; 127 128 fail_dump(attr); 129 130 if (atomic_read(&attr->times) != -1) 131 atomic_dec_not_zero(&attr->times); 132 133 return true; 134 } 135 136 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 137 138 static void debugfs_ul_set(void *data, u64 val) 139 { 140 *(unsigned long *)data = val; 141 } 142 143 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 } 149 150 static u64 debugfs_ul_get(void *data) 151 { 152 return *(unsigned long *)data; 153 } 154 155 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 156 157 static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 158 struct dentry *parent, unsigned long *value) 159 { 160 return debugfs_create_file(name, mode, parent, value, &fops_ul); 161 } 162 163 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, 164 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); 165 166 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 167 const char *name, mode_t mode, 168 struct dentry *parent, unsigned long *value) 169 { 170 return debugfs_create_file(name, mode, parent, value, 171 &fops_ul_MAX_STACK_TRACE_DEPTH); 172 } 173 174 static void debugfs_atomic_t_set(void *data, u64 val) 175 { 176 atomic_set((atomic_t *)data, val); 177 } 178 179 static u64 debugfs_atomic_t_get(void *data) 180 { 181 return atomic_read((atomic_t *)data); 182 } 183 184 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, 185 debugfs_atomic_t_set, "%lld\n"); 186 187 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, 188 struct dentry *parent, atomic_t *value) 189 { 190 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); 191 } 192 193 void cleanup_fault_attr_dentries(struct fault_attr *attr) 194 { 195 debugfs_remove(attr->dentries.probability_file); 196 attr->dentries.probability_file = NULL; 197 198 debugfs_remove(attr->dentries.interval_file); 199 attr->dentries.interval_file = NULL; 200 201 debugfs_remove(attr->dentries.times_file); 202 attr->dentries.times_file = NULL; 203 204 debugfs_remove(attr->dentries.space_file); 205 attr->dentries.space_file = NULL; 206 207 debugfs_remove(attr->dentries.verbose_file); 208 attr->dentries.verbose_file = NULL; 209 210 debugfs_remove(attr->dentries.task_filter_file); 211 attr->dentries.task_filter_file = NULL; 212 213 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 214 215 debugfs_remove(attr->dentries.stacktrace_depth_file); 216 attr->dentries.stacktrace_depth_file = NULL; 217 218 debugfs_remove(attr->dentries.require_start_file); 219 attr->dentries.require_start_file = NULL; 220 221 debugfs_remove(attr->dentries.require_end_file); 222 attr->dentries.require_end_file = NULL; 223 224 debugfs_remove(attr->dentries.reject_start_file); 225 attr->dentries.reject_start_file = NULL; 226 227 debugfs_remove(attr->dentries.reject_end_file); 228 attr->dentries.reject_end_file = NULL; 229 230 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 231 232 if (attr->dentries.dir) 233 WARN_ON(!simple_empty(attr->dentries.dir)); 234 235 debugfs_remove(attr->dentries.dir); 236 attr->dentries.dir = NULL; 237 } 238 239 int init_fault_attr_dentries(struct fault_attr *attr, const char *name) 240 { 241 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 242 struct dentry *dir; 243 244 memset(&attr->dentries, 0, sizeof(attr->dentries)); 245 246 dir = debugfs_create_dir(name, NULL); 247 if (!dir) 248 goto fail; 249 attr->dentries.dir = dir; 250 251 attr->dentries.probability_file = 252 debugfs_create_ul("probability", mode, dir, &attr->probability); 253 254 attr->dentries.interval_file = 255 debugfs_create_ul("interval", mode, dir, &attr->interval); 256 257 attr->dentries.times_file = 258 debugfs_create_atomic_t("times", mode, dir, &attr->times); 259 260 attr->dentries.space_file = 261 debugfs_create_atomic_t("space", mode, dir, &attr->space); 262 263 attr->dentries.verbose_file = 264 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 265 266 attr->dentries.task_filter_file = debugfs_create_bool("task-filter", 267 mode, dir, &attr->task_filter); 268 269 if (!attr->dentries.probability_file || !attr->dentries.interval_file || 270 !attr->dentries.times_file || !attr->dentries.space_file || 271 !attr->dentries.verbose_file || !attr->dentries.task_filter_file) 272 goto fail; 273 274 #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 275 276 attr->dentries.stacktrace_depth_file = 277 debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 278 "stacktrace-depth", mode, dir, &attr->stacktrace_depth); 279 280 attr->dentries.require_start_file = 281 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 282 283 attr->dentries.require_end_file = 284 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 285 286 attr->dentries.reject_start_file = 287 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 288 289 attr->dentries.reject_end_file = 290 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 291 292 if (!attr->dentries.stacktrace_depth_file || 293 !attr->dentries.require_start_file || 294 !attr->dentries.require_end_file || 295 !attr->dentries.reject_start_file || 296 !attr->dentries.reject_end_file) 297 goto fail; 298 299 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 300 301 return 0; 302 fail: 303 cleanup_fault_attr_dentries(attr); 304 return -ENOMEM; 305 } 306 307 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 308