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 #ifdef CONFIG_STACK_UNWIND
  57
  58 static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
  59                                                 void *arg)
  60 {
  61         int depth;
  62         struct fault_attr *attr = arg;
  63         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
  64
  65         for (depth = 0; depth < attr->stacktrace_depth
  66                         && unwind(info) == 0 && UNW_PC(info); depth++) {
  67                 if (arch_unw_user_mode(info))
  68                         break;
  69                 if (attr->reject_start <= UNW_PC(info) &&
  70                                UNW_PC(info) < attr->reject_end)
  71                         return false;
  72                 if (attr->require_start <= UNW_PC(info) &&
  73                                UNW_PC(info) < attr->require_end)
  74                         found = true;
  75         }
  76         return found;
  77 }
  78
  79 static bool fail_stacktrace(struct fault_attr *attr)
  80 {
  81         struct unwind_frame_info info;
  82
  83         return unwind_init_running(&info, fail_stacktrace_callback, attr);
  84 }
  85
  86 #elif defined(CONFIG_STACKTRACE)
  87
  88 static bool fail_stacktrace(struct fault_attr *attr)
  89 {
  90         struct stack_trace trace;
  91         int depth = attr->stacktrace_depth;
  92         unsigned long entries[MAX_STACK_TRACE_DEPTH];
  93         int n;
  94         bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
  95
  96         if (depth == 0)
  97                 return found;
  98
  99         trace.nr_entries = 0;
 100         trace.entries = entries;
 101         trace.max_entries = (depth < MAX_STACK_TRACE_DEPTH) ?
 102                                 depth : MAX_STACK_TRACE_DEPTH;
 103         trace.skip = 1;
 104         trace.all_contexts = 0;
 105
 106         save_stack_trace(&trace, NULL);
 107         for (n = 0; n < trace.nr_entries; n++) {
 108                 if (attr->reject_start <= entries[n] &&
 109                                entries[n] < attr->reject_end)
 110                         return false;
 111                 if (attr->require_start <= entries[n] &&
 112                                entries[n] < attr->require_end)
 113                         found = true;
 114         }
 115         return found;
 116 }
 117
 118 #else
 119
 120 static inline bool fail_stacktrace(struct fault_attr *attr)
 121 {
 122         static bool firsttime = true;
 123
 124         if (firsttime) {
 125                 printk(KERN_WARNING
 126                 "This architecture does not implement save_stack_trace()\n");
 127                 firsttime = false;
 128         }
 129         return false;
 130 }
 131
 132 #endif
 133
 134 /*
 135  * This code is stolen from failmalloc-1.0
 136  * http://www.nongnu.org/failmalloc/
 137  */
 138
 139 bool should_fail(struct fault_attr *attr, ssize_t size)
 140 {
 141         if (attr->task_filter && !fail_task(attr, current))
 142                 return false;
 143
 144         if (!fail_stacktrace(attr))
 145                 return false;
 146
 147         if (atomic_read(&attr->times) == 0)
 148                 return false;
 149
 150         if (atomic_read(&attr->space) > size) {
 151                 atomic_sub(size, &attr->space);
 152                 return false;
 153         }
 154
 155         if (attr->interval > 1) {
 156                 attr->count++;
 157                 if (attr->count % attr->interval)
 158                         return false;
 159         }
 160
 161         if (attr->probability > random32() % 100)
 162                 goto fail;
 163
 164         return false;
 165
 166 fail:
 167         fail_dump(attr);
 168
 169         if (atomic_read(&attr->times) != -1)
 170                 atomic_dec_not_zero(&attr->times);
 171
 172         return true;
 173 }
 174
 175 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 176
 177 static void debugfs_ul_set(void *data, u64 val)
 178 {
 179         *(unsigned long *)data = val;
 180 }
 181
 182 static u64 debugfs_ul_get(void *data)
 183 {
 184         return *(unsigned long *)data;
 185 }
 186
 187 DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
 188
 189 static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
 190                                 struct dentry *parent, unsigned long *value)
 191 {
 192         return debugfs_create_file(name, mode, parent, value, &fops_ul);
 193 }
 194
 195 static void debugfs_atomic_t_set(void *data, u64 val)
 196 {
 197         atomic_set((atomic_t *)data, val);
 198 }
 199
 200 static u64 debugfs_atomic_t_get(void *data)
 201 {
 202         return atomic_read((atomic_t *)data);
 203 }
 204
 205 DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
 206                         debugfs_atomic_t_set, "%lld\n");
 207
 208 static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 209                                 struct dentry *parent, atomic_t *value)
 210 {
 211         return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 212 }
 213
 214 void cleanup_fault_attr_dentries(struct fault_attr *attr)
 215 {
 216         debugfs_remove(attr->dentries.probability_file);
 217         attr->dentries.probability_file = NULL;
 218
 219         debugfs_remove(attr->dentries.interval_file);
 220         attr->dentries.interval_file = NULL;
 221
 222         debugfs_remove(attr->dentries.times_file);
 223         attr->dentries.times_file = NULL;
 224
 225         debugfs_remove(attr->dentries.space_file);
 226         attr->dentries.space_file = NULL;
 227
 228         debugfs_remove(attr->dentries.verbose_file);
 229         attr->dentries.verbose_file = NULL;
 230
 231         debugfs_remove(attr->dentries.task_filter_file);
 232         attr->dentries.task_filter_file = NULL;
 233
 234         debugfs_remove(attr->dentries.stacktrace_depth_file);
 235         attr->dentries.stacktrace_depth_file = NULL;
 236
 237         debugfs_remove(attr->dentries.require_start_file);
 238         attr->dentries.require_start_file = NULL;
 239
 240         debugfs_remove(attr->dentries.require_end_file);
 241         attr->dentries.require_end_file = NULL;
 242
 243         debugfs_remove(attr->dentries.reject_start_file);
 244         attr->dentries.reject_start_file = NULL;
 245
 246         debugfs_remove(attr->dentries.reject_end_file);
 247         attr->dentries.reject_end_file = NULL;
 248
 249         if (attr->dentries.dir)
 250                 WARN_ON(!simple_empty(attr->dentries.dir));
 251
 252         debugfs_remove(attr->dentries.dir);
 253         attr->dentries.dir = NULL;
 254 }
 255
 256 int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 257 {
 258         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 259         struct dentry *dir;
 260
 261         memset(&attr->dentries, 0, sizeof(attr->dentries));
 262
 263         dir = debugfs_create_dir(name, NULL);
 264         if (!dir)
 265                 goto fail;
 266         attr->dentries.dir = dir;
 267
 268         attr->dentries.probability_file =
 269                 debugfs_create_ul("probability", mode, dir, &attr->probability);
 270
 271         attr->dentries.interval_file =
 272                 debugfs_create_ul("interval", mode, dir, &attr->interval);
 273
 274         attr->dentries.times_file =
 275                 debugfs_create_atomic_t("times", mode, dir, &attr->times);
 276
 277         attr->dentries.space_file =
 278                 debugfs_create_atomic_t("space", mode, dir, &attr->space);
 279
 280         attr->dentries.verbose_file =
 281                 debugfs_create_ul("verbose", mode, dir, &attr->verbose);
 282
 283         attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 284                                                 mode, dir, &attr->task_filter);
 285
 286         attr->dentries.stacktrace_depth_file =
 287                 debugfs_create_ul("stacktrace-depth", mode, dir,
 288                                   &attr->stacktrace_depth);
 289
 290         attr->dentries.require_start_file =
 291                 debugfs_create_ul("require-start", mode, dir, &attr->require_start);
 292
 293         attr->dentries.require_end_file =
 294                 debugfs_create_ul("require-end", mode, dir, &attr->require_end);
 295
 296         attr->dentries.reject_start_file =
 297                 debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
 298
 299         attr->dentries.reject_end_file =
 300                 debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 301
 302
 303         if (!attr->dentries.probability_file || !attr->dentries.interval_file
 304             || !attr->dentries.times_file || !attr->dentries.space_file
 305             || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
 306             || !attr->dentries.stacktrace_depth_file
 307             || !attr->dentries.require_start_file
 308             || !attr->dentries.require_end_file
 309             || !attr->dentries.reject_start_file
 310             || !attr->dentries.reject_end_file
 311             )
 312                 goto fail;
 313
 314         return 0;
 315 fail:
 316         cleanup_fault_attr_dentries(attr);
 317         return -ENOMEM;
 318 }
 319
 320 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */