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 */ 18int __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 41static 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 51static 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 60static 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 90static 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 102bool 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 137static void debugfs_ul_set(void *data, u64 val) 138{ 139 *(unsigned long *)data = val; 140} 141 142static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val) 143{ 144 *(unsigned long *)data = 145 val < MAX_STACK_TRACE_DEPTH ? 146 val : MAX_STACK_TRACE_DEPTH; 147} 148 149static u64 debugfs_ul_get(void *data) 150{ 151 return *(unsigned long *)data; 152} 153 154DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); 155 156static struct dentry *debugfs_create_ul(const char *name, mode_t mode, 157 struct dentry *parent, unsigned long *value) 158{ 159 return debugfs_create_file(name, mode, parent, value, &fops_ul); 160} 161 162DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get, 163 debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n"); 164 165static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 166 const char *name, mode_t mode, 167 struct dentry *parent, unsigned long *value) 168{ 169 return debugfs_create_file(name, mode, parent, value, 170 &fops_ul_MAX_STACK_TRACE_DEPTH); 171} 172 173static void debugfs_atomic_t_set(void *data, u64 val) 174{ 175 atomic_set((atomic_t *)data, val); 176} 177 178static u64 debugfs_atomic_t_get(void *data) 179{ 180 return atomic_read((atomic_t *)data); 181} 182 183DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, 184 debugfs_atomic_t_set, "%lld\n"); 185 186static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode, 187 struct dentry *parent, atomic_t *value) 188{ 189 return debugfs_create_file(name, mode, parent, value, &fops_atomic_t); 190} 191 192void cleanup_fault_attr_dentries(struct fault_attr *attr) 193{ 194 debugfs_remove(attr->dentries.probability_file); 195 attr->dentries.probability_file = NULL; 196 197 debugfs_remove(attr->dentries.interval_file); 198 attr->dentries.interval_file = NULL; 199 200 debugfs_remove(attr->dentries.times_file); 201 attr->dentries.times_file = NULL; 202 203 debugfs_remove(attr->dentries.space_file); 204 attr->dentries.space_file = NULL; 205 206 debugfs_remove(attr->dentries.verbose_file); 207 attr->dentries.verbose_file = NULL; 208 209 debugfs_remove(attr->dentries.task_filter_file); 210 attr->dentries.task_filter_file = NULL; 211 212#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 213 214 debugfs_remove(attr->dentries.stacktrace_depth_file); 215 attr->dentries.stacktrace_depth_file = NULL; 216 217 debugfs_remove(attr->dentries.require_start_file); 218 attr->dentries.require_start_file = NULL; 219 220 debugfs_remove(attr->dentries.require_end_file); 221 attr->dentries.require_end_file = NULL; 222 223 debugfs_remove(attr->dentries.reject_start_file); 224 attr->dentries.reject_start_file = NULL; 225 226 debugfs_remove(attr->dentries.reject_end_file); 227 attr->dentries.reject_end_file = NULL; 228 229#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 230 231 if (attr->dentries.dir) 232 WARN_ON(!simple_empty(attr->dentries.dir)); 233 234 debugfs_remove(attr->dentries.dir); 235 attr->dentries.dir = NULL; 236} 237 238int init_fault_attr_dentries(struct fault_attr *attr, const char *name) 239{ 240 mode_t mode = S_IFREG | S_IRUSR | S_IWUSR; 241 struct dentry *dir; 242 243 memset(&attr->dentries, 0, sizeof(attr->dentries)); 244 245 dir = debugfs_create_dir(name, NULL); 246 if (!dir) 247 goto fail; 248 attr->dentries.dir = dir; 249 250 attr->dentries.probability_file = 251 debugfs_create_ul("probability", mode, dir, &attr->probability); 252 253 attr->dentries.interval_file = 254 debugfs_create_ul("interval", mode, dir, &attr->interval); 255 256 attr->dentries.times_file = 257 debugfs_create_atomic_t("times", mode, dir, &attr->times); 258 259 attr->dentries.space_file = 260 debugfs_create_atomic_t("space", mode, dir, &attr->space); 261 262 attr->dentries.verbose_file = 263 debugfs_create_ul("verbose", mode, dir, &attr->verbose); 264 265 attr->dentries.task_filter_file = debugfs_create_bool("task-filter", 266 mode, dir, &attr->task_filter); 267 268 if (!attr->dentries.probability_file || !attr->dentries.interval_file || 269 !attr->dentries.times_file || !attr->dentries.space_file || 270 !attr->dentries.verbose_file || !attr->dentries.task_filter_file) 271 goto fail; 272 273#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER 274 275 attr->dentries.stacktrace_depth_file = 276 debugfs_create_ul_MAX_STACK_TRACE_DEPTH( 277 "stacktrace-depth", mode, dir, &attr->stacktrace_depth); 278 279 attr->dentries.require_start_file = 280 debugfs_create_ul("require-start", mode, dir, &attr->require_start); 281 282 attr->dentries.require_end_file = 283 debugfs_create_ul("require-end", mode, dir, &attr->require_end); 284 285 attr->dentries.reject_start_file = 286 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); 287 288 attr->dentries.reject_end_file = 289 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end); 290 291 if (!attr->dentries.stacktrace_depth_file || 292 !attr->dentries.require_start_file || 293 !attr->dentries.require_end_file || 294 !attr->dentries.reject_start_file || 295 !attr->dentries.reject_end_file) 296 goto fail; 297 298#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ 299 300 return 0; 301fail: 302 cleanup_fault_attr_dentries(attr); 303 return -ENOMEM; 304} 305 306#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ 307