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 #if defined(CONFIG_STACKTRACE) 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 static bool firsttime = true; 94 95 if (firsttime) { 96 printk(KERN_WARNING 97 "This architecture does not implement save_stack_trace()\n"); 98 firsttime = false; 99 } 100 return false; 101 } 102 103 #endif 104 105 /* 106 * This code is stolen from failmalloc-1.0 107 * http://www.nongnu.org/failmalloc/ 108 */ 109 110 bool should_fail(struct fault_attr *attr, ssize_t size) 111 { 112 if (attr->task_filter && !fail_task(attr, current)) 113 return false; 114 115 if (atomic_read(&attr->times) == 0) 116 return false; 117 118 if (atomic_read(&attr->space) > size) { 119 atomic_sub(size, &attr->space); 120 return false; 121 } 122 123 if (attr->interval > 1) { 124 attr->count++; 125 if (attr->count % attr->interval) 126 return false; 127 } 128 129 if (attr->probability <= random32() % 100) 130 return false; 131 132 if (!fail_stacktrace(attr)) 133 return false; 134 135 fail_dump(attr); 136 137 if (atomic_read(&attr->times) != -1) 138 atomic_dec_not_zero(&attr->times); 139 140 return true; 141 } 142 143 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS 144 145 static void debugfs_ul_set(void *data, u64 val) 146 { 147 *(unsigned long *)data = val; 148 } 149 150 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val) 151 { 152 *(unsigned long *)data = 153 val < MAX_STACK_TRACE_DEPTH ? 154 val : MAX_STACK_TRACE_DEPTH; 155 } 156 157 static u64 debugfs_ul_get(void *data) 158 { 159 return *(unsigned long *)data; 160 } 161 162 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 163 164 static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 165 struct dentry *parent, unsigned long *value) 166 { 167 return debugfs_create_file(name, mode, parent, value, &fops_ul); 168 } 169 170 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, 171 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); 172 173 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 174 const char *name, mode_t mode, 175 struct dentry *parent, unsigned long *value) 176 { 177 return debugfs_create_file(name, mode, parent, value, 178 &fops_ul_MAX_STACK_TRACE_DEPTH); 179 } 180 181 static void debugfs_atomic_t_set(void *data, u64 val) 182 { 183 atomic_set((atomic_t *)data, val); 184 } 185 186 static u64 debugfs_atomic_t_get(void *data) 187 { 188 return atomic_read((atomic_t *)data); 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 debugfs_remove(attr->dentries.stacktrace_depth_file); 221 attr->dentries.stacktrace_depth_file = NULL; 222 223 debugfs_remove(attr->dentries.require_start_file); 224 attr->dentries.require_start_file = NULL; 225 226 debugfs_remove(attr->dentries.require_end_file); 227 attr->dentries.require_end_file = NULL; 228 229 debugfs_remove(attr->dentries.reject_start_file); 230 attr->dentries.reject_start_file = NULL; 231 232 debugfs_remove(attr->dentries.reject_end_file); 233 attr->dentries.reject_end_file = NULL; 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 attr->dentries.stacktrace_depth_file = 273 debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 274 "stacktrace-depth", mode, dir, &attr->stacktrace_depth); 275 276 attr->dentries.require_start_file = 277 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 278 279 attr->dentries.require_end_file = 280 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 281 282 attr->dentries.reject_start_file = 283 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 284 285 attr->dentries.reject_end_file = 286 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 287 288 289 if (!attr->dentries.probability_file || !attr->dentries.interval_file 290 || !attr->dentries.times_file || !attr->dentries.space_file 291 || !attr->dentries.verbose_file || !attr->dentries.task_filter_file 292 || !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 ) 298 goto fail; 299 300 return 0; 301 fail: 302 cleanup_fault_attr_dentries(attr); 303 return -ENOMEM; 304 } 305 306 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 307