lib/fault-inject.c

   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, &times) < 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_STACK_UNWIND
  59
  60 static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
  61                                                 void *arg)
  62 {
  63         int depth;
  64         struct fault_attr *attr = arg;
  65         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
  66
  67         for (depth = 0; depth < attr->stacktrace_depth
  68                         && unwind(info) == 0 && UNW_PC(info); depth++) {
  69                 if (arch_unw_user_mode(info))
  70                         break;
  71                 if (attr->reject_start <= UNW_PC(info) &&
  72                                UNW_PC(info) < attr->reject_end)
  73                         return false;
  74                 if (attr->require_start <= UNW_PC(info) &&
  75                                UNW_PC(info) < attr->require_end)
  76                         found = true;
  77         }
  78         return found;
  79 }
  80
  81 static bool fail_stacktrace(struct fault_attr *attr)
  82 {
  83         struct unwind_frame_info info;
  84
  85         return unwind_init_running(&info, fail_stacktrace_callback, attr);
  86 }
  87
  88 #elif defined(CONFIG_STACKTRACE)
  89
  90 static bool fail_stacktrace(struct fault_attr *attr)
  91 {
  92         struct stack_trace trace;
  93         int depth = attr->stacktrace_depth;
  94         unsigned long entries[MAX_STACK_TRACE_DEPTH];
  95         int n;
  96         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
  97
  98         if (depth == 0)
  99                 return found;
 100
 101         trace.nr_entries = 0;
 102         trace.entries = entries;
 103         trace.max_entries = depth;
 104         trace.skip = 1;
 105         trace.all_contexts = 0;
 106
 107         save_stack_trace(&trace, NULL);
 108         for (n = 0; n < trace.nr_entries; n++) {
 109                 if (attr->reject_start <= entries[n] &&
 110                                entries[n] < attr->reject_end)
 111                         return false;
 112                 if (attr->require_start <= entries[n] &&
 113                                entries[n] < attr->require_end)
 114                         found = true;
 115         }
 116         return found;
 117 }
 118
 119 #else
 120
 121 static inline bool fail_stacktrace(struct fault_attr *attr)
 122 {
 123         static bool firsttime = true;
 124
 125         if (firsttime) {
 126                 printk(KERN_WARNING
 127                 "This architecture does not implement save_stack_trace()\n");
 128                 firsttime = false;
 129         }
 130         return false;
 131 }
 132
 133 #endif
 134
 135 /*
 136  * This code is stolen from failmalloc-1.0
 137  * http://www.nongnu.org/failmalloc/
 138  */
 139
 140 bool should_fail(struct fault_attr *attr, ssize_t size)
 141 {
 142         if (attr->task_filter && !fail_task(attr, current))
 143                 return false;
 144
 145         if (!fail_stacktrace(attr))
 146                 return false;
 147
 148         if (atomic_read(&attr->times) == 0)
 149                 return false;
 150
 151         if (atomic_read(&attr->space) > size) {
 152                 atomic_sub(size, &attr->space);
 153                 return false;
 154         }
 155
 156         if (attr->interval > 1) {
 157                 attr->count++;
 158                 if (attr->count % attr->interval)
 159                         return false;
 160         }
 161
 162         if (attr->probability > random32() % 100)
 163                 goto fail;
 164
 165         return false;
 166
 167 fail:
 168         fail_dump(attr);
 169
 170         if (atomic_read(&attr->times) != -1)
 171                 atomic_dec_not_zero(&attr->times);
 172
 173         return true;
 174 }
 175
 176 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 177
 178 static void debugfs_ul_set(void *data, u64 val)
 179 {
 180         *(unsigned long *)data = val;
 181 }
 182
 183 static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
 184 {
 185         *(unsigned long *)data =
 186                 val < MAX_STACK_TRACE_DEPTH ?
 187                 val : MAX_STACK_TRACE_DEPTH;
 188 }
 189
 190 static u64 debugfs_ul_get(void *data)
 191 {
 192         return *(unsigned long *)data;
 193 }
 194
 195 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 196
 197 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 198                                 struct dentry *parent, unsigned long *value)
 199 {
 200         return debugfs_create_file(name, mode, parent, value, &fops_ul);
 201 }
 202
 203 DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
 204                         debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
 205
 206 static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 207         const char *name, mode_t mode,
 208         struct dentry *parent, unsigned long *value)
 209 {
 210         return debugfs_create_file(name, mode, parent, value,
 211                                    &fops_ul_MAX_STACK_TRACE_DEPTH);
 212 }
 213
 214 static void debugfs_atomic_t_set(void *data, u64 val)
 215 {
 216         atomic_set((atomic_t *)data, val);
 217 }
 218
 219 static u64 debugfs_atomic_t_get(void *data)
 220 {
 221         return atomic_read((atomic_t *)data);
 222 }
 223
 224 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
 225                         debugfs_atomic_t_set, "%lld\n");
 226
 227 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 228                                 struct dentry *parent, atomic_t *value)
 229 {
 230         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 231 }
 232
 233 void cleanup_fault_attr_dentries(struct fault_attr *attr)
 234 {
 235         debugfs_remove(attr->dentries.probability_file);
 236         attr->dentries.probability_file = NULL;
 237
 238         debugfs_remove(attr->dentries.interval_file);
 239         attr->dentries.interval_file = NULL;
 240
 241         debugfs_remove(attr->dentries.times_file);
 242         attr->dentries.times_file = NULL;
 243
 244         debugfs_remove(attr->dentries.space_file);
 245         attr->dentries.space_file = NULL;
 246
 247         debugfs_remove(attr->dentries.verbose_file);
 248         attr->dentries.verbose_file = NULL;
 249
 250         debugfs_remove(attr->dentries.task_filter_file);
 251         attr->dentries.task_filter_file = NULL;
 252
 253         debugfs_remove(attr->dentries.stacktrace_depth_file);
 254         attr->dentries.stacktrace_depth_file = NULL;
 255
 256         debugfs_remove(attr->dentries.require_start_file);
 257         attr->dentries.require_start_file = NULL;
 258
 259         debugfs_remove(attr->dentries.require_end_file);
 260         attr->dentries.require_end_file = NULL;
 261
 262         debugfs_remove(attr->dentries.reject_start_file);
 263         attr->dentries.reject_start_file = NULL;
 264
 265         debugfs_remove(attr->dentries.reject_end_file);
 266         attr->dentries.reject_end_file = NULL;
 267
 268         if (attr->dentries.dir)
 269                 WARN_ON(!simple_empty(attr->dentries.dir));
 270
 271         debugfs_remove(attr->dentries.dir);
 272         attr->dentries.dir = NULL;
 273 }
 274
 275 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 276 {
 277         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 278         struct dentry *dir;
 279
 280         memset(&attr->dentries, 0, sizeof(attr->dentries));
 281
 282         dir = debugfs_create_dir(name, NULL);
 283         if (!dir)
 284                 goto fail;
 285         attr->dentries.dir = dir;
 286
 287         attr->dentries.probability_file =
 288                 debugfs_create_ul("probability", mode, dir, &attr->probability);
 289
 290         attr->dentries.interval_file =
 291                 debugfs_create_ul("interval", mode, dir, &attr->interval);
 292
 293         attr->dentries.times_file =
 294                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
 295
 296         attr->dentries.space_file =
 297                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
 298
 299         attr->dentries.verbose_file =
 300                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 301
 302         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 303                                                 mode, dir, &attr->task_filter);
 304
 305         attr->dentries.stacktrace_depth_file =
 306                 debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 307                         "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
 308
 309         attr->dentries.require_start_file =
 310                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 311
 312         attr->dentries.require_end_file =
 313                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 314
 315         attr->dentries.reject_start_file =
 316                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 317
 318         attr->dentries.reject_end_file =
 319                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 320
 321
 322         if (!attr->dentries.probability_file || !attr->dentries.interval_file
 323             || !attr->dentries.times_file || !attr->dentries.space_file
 324             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
 325             || !attr->dentries.stacktrace_depth_file
 326             || !attr->dentries.require_start_file
 327             || !attr->dentries.require_end_file
 328             || !attr->dentries.reject_start_file
 329             || !attr->dentries.reject_end_file
 330             )
 331                 goto fail;
 332
 333         return 0;
 334 fail:
 335         cleanup_fault_attr_dentries(attr);
 336         return -ENOMEM;
 337 }
 338
 339 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */