| 1 | /* |
| 2 | * trace event based perf event profiling/tracing |
| 3 | * |
| 4 | * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com> |
| 5 | * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/kprobes.h> |
| 10 | #include "trace.h" |
| 11 | |
| 12 | static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS]; |
| 13 | |
| 14 | /* |
| 15 | * Force it to be aligned to unsigned long to avoid misaligned accesses |
| 16 | * suprises |
| 17 | */ |
| 18 | typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)]) |
| 19 | perf_trace_t; |
| 20 | |
| 21 | /* Count the events in use (per event id, not per instance) */ |
| 22 | static int total_ref_count; |
| 23 | |
| 24 | static int perf_trace_event_perm(struct ftrace_event_call *tp_event, |
| 25 | struct perf_event *p_event) |
| 26 | { |
| 27 | /* The ftrace function trace is allowed only for root. */ |
| 28 | if (ftrace_event_is_function(tp_event) && |
| 29 | perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) |
| 30 | return -EPERM; |
| 31 | |
| 32 | /* No tracing, just counting, so no obvious leak */ |
| 33 | if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) |
| 34 | return 0; |
| 35 | |
| 36 | /* Some events are ok to be traced by non-root users... */ |
| 37 | if (p_event->attach_state == PERF_ATTACH_TASK) { |
| 38 | if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY) |
| 39 | return 0; |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * ...otherwise raw tracepoint data can be a severe data leak, |
| 44 | * only allow root to have these. |
| 45 | */ |
| 46 | if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) |
| 47 | return -EPERM; |
| 48 | |
| 49 | return 0; |
| 50 | } |
| 51 | |
| 52 | static int perf_trace_event_reg(struct ftrace_event_call *tp_event, |
| 53 | struct perf_event *p_event) |
| 54 | { |
| 55 | struct hlist_head __percpu *list; |
| 56 | int ret = -ENOMEM; |
| 57 | int cpu; |
| 58 | |
| 59 | p_event->tp_event = tp_event; |
| 60 | if (tp_event->perf_refcount++ > 0) |
| 61 | return 0; |
| 62 | |
| 63 | list = alloc_percpu(struct hlist_head); |
| 64 | if (!list) |
| 65 | goto fail; |
| 66 | |
| 67 | for_each_possible_cpu(cpu) |
| 68 | INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); |
| 69 | |
| 70 | tp_event->perf_events = list; |
| 71 | |
| 72 | if (!total_ref_count) { |
| 73 | char __percpu *buf; |
| 74 | int i; |
| 75 | |
| 76 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
| 77 | buf = (char __percpu *)alloc_percpu(perf_trace_t); |
| 78 | if (!buf) |
| 79 | goto fail; |
| 80 | |
| 81 | perf_trace_buf[i] = buf; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); |
| 86 | if (ret) |
| 87 | goto fail; |
| 88 | |
| 89 | total_ref_count++; |
| 90 | return 0; |
| 91 | |
| 92 | fail: |
| 93 | if (!total_ref_count) { |
| 94 | int i; |
| 95 | |
| 96 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
| 97 | free_percpu(perf_trace_buf[i]); |
| 98 | perf_trace_buf[i] = NULL; |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | if (!--tp_event->perf_refcount) { |
| 103 | free_percpu(tp_event->perf_events); |
| 104 | tp_event->perf_events = NULL; |
| 105 | } |
| 106 | |
| 107 | return ret; |
| 108 | } |
| 109 | |
| 110 | static void perf_trace_event_unreg(struct perf_event *p_event) |
| 111 | { |
| 112 | struct ftrace_event_call *tp_event = p_event->tp_event; |
| 113 | int i; |
| 114 | |
| 115 | if (--tp_event->perf_refcount > 0) |
| 116 | goto out; |
| 117 | |
| 118 | tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); |
| 119 | |
| 120 | /* |
| 121 | * Ensure our callback won't be called anymore. The buffers |
| 122 | * will be freed after that. |
| 123 | */ |
| 124 | tracepoint_synchronize_unregister(); |
| 125 | |
| 126 | free_percpu(tp_event->perf_events); |
| 127 | tp_event->perf_events = NULL; |
| 128 | |
| 129 | if (!--total_ref_count) { |
| 130 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
| 131 | free_percpu(perf_trace_buf[i]); |
| 132 | perf_trace_buf[i] = NULL; |
| 133 | } |
| 134 | } |
| 135 | out: |
| 136 | module_put(tp_event->mod); |
| 137 | } |
| 138 | |
| 139 | static int perf_trace_event_open(struct perf_event *p_event) |
| 140 | { |
| 141 | struct ftrace_event_call *tp_event = p_event->tp_event; |
| 142 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); |
| 143 | } |
| 144 | |
| 145 | static void perf_trace_event_close(struct perf_event *p_event) |
| 146 | { |
| 147 | struct ftrace_event_call *tp_event = p_event->tp_event; |
| 148 | tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); |
| 149 | } |
| 150 | |
| 151 | static int perf_trace_event_init(struct ftrace_event_call *tp_event, |
| 152 | struct perf_event *p_event) |
| 153 | { |
| 154 | int ret; |
| 155 | |
| 156 | ret = perf_trace_event_perm(tp_event, p_event); |
| 157 | if (ret) |
| 158 | return ret; |
| 159 | |
| 160 | ret = perf_trace_event_reg(tp_event, p_event); |
| 161 | if (ret) |
| 162 | return ret; |
| 163 | |
| 164 | ret = perf_trace_event_open(p_event); |
| 165 | if (ret) { |
| 166 | perf_trace_event_unreg(p_event); |
| 167 | return ret; |
| 168 | } |
| 169 | |
| 170 | return 0; |
| 171 | } |
| 172 | |
| 173 | int perf_trace_init(struct perf_event *p_event) |
| 174 | { |
| 175 | struct ftrace_event_call *tp_event; |
| 176 | int event_id = p_event->attr.config; |
| 177 | int ret = -EINVAL; |
| 178 | |
| 179 | mutex_lock(&event_mutex); |
| 180 | list_for_each_entry(tp_event, &ftrace_events, list) { |
| 181 | if (tp_event->event.type == event_id && |
| 182 | tp_event->class && tp_event->class->reg && |
| 183 | try_module_get(tp_event->mod)) { |
| 184 | ret = perf_trace_event_init(tp_event, p_event); |
| 185 | if (ret) |
| 186 | module_put(tp_event->mod); |
| 187 | break; |
| 188 | } |
| 189 | } |
| 190 | mutex_unlock(&event_mutex); |
| 191 | |
| 192 | return ret; |
| 193 | } |
| 194 | |
| 195 | void perf_trace_destroy(struct perf_event *p_event) |
| 196 | { |
| 197 | mutex_lock(&event_mutex); |
| 198 | perf_trace_event_close(p_event); |
| 199 | perf_trace_event_unreg(p_event); |
| 200 | mutex_unlock(&event_mutex); |
| 201 | } |
| 202 | |
| 203 | int perf_trace_add(struct perf_event *p_event, int flags) |
| 204 | { |
| 205 | struct ftrace_event_call *tp_event = p_event->tp_event; |
| 206 | struct hlist_head __percpu *pcpu_list; |
| 207 | struct hlist_head *list; |
| 208 | |
| 209 | pcpu_list = tp_event->perf_events; |
| 210 | if (WARN_ON_ONCE(!pcpu_list)) |
| 211 | return -EINVAL; |
| 212 | |
| 213 | if (!(flags & PERF_EF_START)) |
| 214 | p_event->hw.state = PERF_HES_STOPPED; |
| 215 | |
| 216 | list = this_cpu_ptr(pcpu_list); |
| 217 | hlist_add_head_rcu(&p_event->hlist_entry, list); |
| 218 | |
| 219 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event); |
| 220 | } |
| 221 | |
| 222 | void perf_trace_del(struct perf_event *p_event, int flags) |
| 223 | { |
| 224 | struct ftrace_event_call *tp_event = p_event->tp_event; |
| 225 | hlist_del_rcu(&p_event->hlist_entry); |
| 226 | tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event); |
| 227 | } |
| 228 | |
| 229 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
| 230 | struct pt_regs *regs, int *rctxp) |
| 231 | { |
| 232 | struct trace_entry *entry; |
| 233 | unsigned long flags; |
| 234 | char *raw_data; |
| 235 | int pc; |
| 236 | |
| 237 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
| 238 | |
| 239 | if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, |
| 240 | "perf buffer not large enough")) |
| 241 | return NULL; |
| 242 | |
| 243 | pc = preempt_count(); |
| 244 | |
| 245 | *rctxp = perf_swevent_get_recursion_context(); |
| 246 | if (*rctxp < 0) |
| 247 | return NULL; |
| 248 | |
| 249 | raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); |
| 250 | |
| 251 | /* zero the dead bytes from align to not leak stack to user */ |
| 252 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
| 253 | |
| 254 | entry = (struct trace_entry *)raw_data; |
| 255 | local_save_flags(flags); |
| 256 | tracing_generic_entry_update(entry, flags, pc); |
| 257 | entry->type = type; |
| 258 | |
| 259 | return raw_data; |
| 260 | } |
| 261 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |
| 262 | |
| 263 | #ifdef CONFIG_FUNCTION_TRACER |
| 264 | static void |
| 265 | perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, |
| 266 | struct ftrace_ops *ops, struct pt_regs *pt_regs) |
| 267 | { |
| 268 | struct ftrace_entry *entry; |
| 269 | struct hlist_head *head; |
| 270 | struct pt_regs regs; |
| 271 | int rctx; |
| 272 | |
| 273 | head = this_cpu_ptr(event_function.perf_events); |
| 274 | if (hlist_empty(head)) |
| 275 | return; |
| 276 | |
| 277 | #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ |
| 278 | sizeof(u64)) - sizeof(u32)) |
| 279 | |
| 280 | BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); |
| 281 | |
| 282 | perf_fetch_caller_regs(®s); |
| 283 | |
| 284 | entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx); |
| 285 | if (!entry) |
| 286 | return; |
| 287 | |
| 288 | entry->ip = ip; |
| 289 | entry->parent_ip = parent_ip; |
| 290 | perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0, |
| 291 | 1, ®s, head, NULL); |
| 292 | |
| 293 | #undef ENTRY_SIZE |
| 294 | } |
| 295 | |
| 296 | static int perf_ftrace_function_register(struct perf_event *event) |
| 297 | { |
| 298 | struct ftrace_ops *ops = &event->ftrace_ops; |
| 299 | |
| 300 | ops->flags |= FTRACE_OPS_FL_CONTROL; |
| 301 | ops->func = perf_ftrace_function_call; |
| 302 | return register_ftrace_function(ops); |
| 303 | } |
| 304 | |
| 305 | static int perf_ftrace_function_unregister(struct perf_event *event) |
| 306 | { |
| 307 | struct ftrace_ops *ops = &event->ftrace_ops; |
| 308 | int ret = unregister_ftrace_function(ops); |
| 309 | ftrace_free_filter(ops); |
| 310 | return ret; |
| 311 | } |
| 312 | |
| 313 | static void perf_ftrace_function_enable(struct perf_event *event) |
| 314 | { |
| 315 | ftrace_function_local_enable(&event->ftrace_ops); |
| 316 | } |
| 317 | |
| 318 | static void perf_ftrace_function_disable(struct perf_event *event) |
| 319 | { |
| 320 | ftrace_function_local_disable(&event->ftrace_ops); |
| 321 | } |
| 322 | |
| 323 | int perf_ftrace_event_register(struct ftrace_event_call *call, |
| 324 | enum trace_reg type, void *data) |
| 325 | { |
| 326 | switch (type) { |
| 327 | case TRACE_REG_REGISTER: |
| 328 | case TRACE_REG_UNREGISTER: |
| 329 | break; |
| 330 | case TRACE_REG_PERF_REGISTER: |
| 331 | case TRACE_REG_PERF_UNREGISTER: |
| 332 | return 0; |
| 333 | case TRACE_REG_PERF_OPEN: |
| 334 | return perf_ftrace_function_register(data); |
| 335 | case TRACE_REG_PERF_CLOSE: |
| 336 | return perf_ftrace_function_unregister(data); |
| 337 | case TRACE_REG_PERF_ADD: |
| 338 | perf_ftrace_function_enable(data); |
| 339 | return 0; |
| 340 | case TRACE_REG_PERF_DEL: |
| 341 | perf_ftrace_function_disable(data); |
| 342 | return 0; |
| 343 | } |
| 344 | |
| 345 | return -EINVAL; |
| 346 | } |
| 347 | #endif /* CONFIG_FUNCTION_TRACER */ |