| 1 | #include <linux/kernel.h> |
| 2 | #include <linux/init.h> |
| 3 | #include <linux/random.h> |
| 4 | #include <linux/sched.h> |
| 5 | #include <linux/stat.h> |
| 6 | #include <linux/types.h> |
| 7 | #include <linux/fs.h> |
| 8 | #include <linux/export.h> |
| 9 | #include <linux/interrupt.h> |
| 10 | #include <linux/stacktrace.h> |
| 11 | #include <linux/fault-inject.h> |
| 12 | |
| 13 | /* |
| 14 | * setup_fault_attr() is a helper function for various __setup handlers, so it |
| 15 | * returns 0 on error, because that is what __setup handlers do. |
| 16 | */ |
| 17 | int setup_fault_attr(struct fault_attr *attr, char *str) |
| 18 | { |
| 19 | unsigned long probability; |
| 20 | unsigned long interval; |
| 21 | int times; |
| 22 | int space; |
| 23 | |
| 24 | /* "<interval>,<probability>,<space>,<times>" */ |
| 25 | if (sscanf(str, "%lu,%lu,%d,%d", |
| 26 | &interval, &probability, &space, ×) < 4) { |
| 27 | printk(KERN_WARNING |
| 28 | "FAULT_INJECTION: failed to parse arguments\n"); |
| 29 | return 0; |
| 30 | } |
| 31 | |
| 32 | attr->probability = probability; |
| 33 | attr->interval = interval; |
| 34 | atomic_set(&attr->times, times); |
| 35 | atomic_set(&attr->space, space); |
| 36 | |
| 37 | return 1; |
| 38 | } |
| 39 | EXPORT_SYMBOL_GPL(setup_fault_attr); |
| 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 | |
| 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 | |
| 90 | static 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 | |
| 102 | bool should_fail(struct fault_attr *attr, ssize_t size) |
| 103 | { |
| 104 | /* No need to check any other properties if the probability is 0 */ |
| 105 | if (attr->probability == 0) |
| 106 | return false; |
| 107 | |
| 108 | if (attr->task_filter && !fail_task(attr, current)) |
| 109 | return false; |
| 110 | |
| 111 | if (atomic_read(&attr->times) == 0) |
| 112 | return false; |
| 113 | |
| 114 | if (atomic_read(&attr->space) > size) { |
| 115 | atomic_sub(size, &attr->space); |
| 116 | return false; |
| 117 | } |
| 118 | |
| 119 | if (attr->interval > 1) { |
| 120 | attr->count++; |
| 121 | if (attr->count % attr->interval) |
| 122 | return false; |
| 123 | } |
| 124 | |
| 125 | if (attr->probability <= prandom_u32() % 100) |
| 126 | return false; |
| 127 | |
| 128 | if (!fail_stacktrace(attr)) |
| 129 | return false; |
| 130 | |
| 131 | fail_dump(attr); |
| 132 | |
| 133 | if (atomic_read(&attr->times) != -1) |
| 134 | atomic_dec_not_zero(&attr->times); |
| 135 | |
| 136 | return true; |
| 137 | } |
| 138 | EXPORT_SYMBOL_GPL(should_fail); |
| 139 | |
| 140 | #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS |
| 141 | |
| 142 | static int debugfs_ul_set(void *data, u64 val) |
| 143 | { |
| 144 | *(unsigned long *)data = val; |
| 145 | return 0; |
| 146 | } |
| 147 | |
| 148 | static int debugfs_ul_get(void *data, u64 *val) |
| 149 | { |
| 150 | *val = *(unsigned long *)data; |
| 151 | return 0; |
| 152 | } |
| 153 | |
| 154 | DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n"); |
| 155 | |
| 156 | static struct dentry *debugfs_create_ul(const char *name, umode_t mode, |
| 157 | struct dentry *parent, unsigned long *value) |
| 158 | { |
| 159 | return debugfs_create_file(name, mode, parent, value, &fops_ul); |
| 160 | } |
| 161 | |
| 162 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER |
| 163 | |
| 164 | static int debugfs_stacktrace_depth_set(void *data, u64 val) |
| 165 | { |
| 166 | *(unsigned long *)data = |
| 167 | min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH); |
| 168 | |
| 169 | return 0; |
| 170 | } |
| 171 | |
| 172 | DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get, |
| 173 | debugfs_stacktrace_depth_set, "%llu\n"); |
| 174 | |
| 175 | static struct dentry *debugfs_create_stacktrace_depth( |
| 176 | const char *name, umode_t mode, |
| 177 | struct dentry *parent, unsigned long *value) |
| 178 | { |
| 179 | return debugfs_create_file(name, mode, parent, value, |
| 180 | &fops_stacktrace_depth); |
| 181 | } |
| 182 | |
| 183 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
| 184 | |
| 185 | struct dentry *fault_create_debugfs_attr(const char *name, |
| 186 | struct dentry *parent, struct fault_attr *attr) |
| 187 | { |
| 188 | umode_t mode = S_IFREG | S_IRUSR | S_IWUSR; |
| 189 | struct dentry *dir; |
| 190 | |
| 191 | dir = debugfs_create_dir(name, parent); |
| 192 | if (!dir) |
| 193 | return ERR_PTR(-ENOMEM); |
| 194 | |
| 195 | if (!debugfs_create_ul("probability", mode, dir, &attr->probability)) |
| 196 | goto fail; |
| 197 | if (!debugfs_create_ul("interval", mode, dir, &attr->interval)) |
| 198 | goto fail; |
| 199 | if (!debugfs_create_atomic_t("times", mode, dir, &attr->times)) |
| 200 | goto fail; |
| 201 | if (!debugfs_create_atomic_t("space", mode, dir, &attr->space)) |
| 202 | goto fail; |
| 203 | if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose)) |
| 204 | goto fail; |
| 205 | if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter)) |
| 206 | goto fail; |
| 207 | |
| 208 | #ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER |
| 209 | |
| 210 | if (!debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir, |
| 211 | &attr->stacktrace_depth)) |
| 212 | goto fail; |
| 213 | if (!debugfs_create_ul("require-start", mode, dir, |
| 214 | &attr->require_start)) |
| 215 | goto fail; |
| 216 | if (!debugfs_create_ul("require-end", mode, dir, &attr->require_end)) |
| 217 | goto fail; |
| 218 | if (!debugfs_create_ul("reject-start", mode, dir, &attr->reject_start)) |
| 219 | goto fail; |
| 220 | if (!debugfs_create_ul("reject-end", mode, dir, &attr->reject_end)) |
| 221 | goto fail; |
| 222 | |
| 223 | #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */ |
| 224 | |
| 225 | return dir; |
| 226 | fail: |
| 227 | debugfs_remove_recursive(dir); |
| 228 | |
| 229 | return ERR_PTR(-ENOMEM); |
| 230 | } |
| 231 | EXPORT_SYMBOL_GPL(fault_create_debugfs_attr); |
| 232 | |
| 233 | #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |