kernel/trace/trace_kprobe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Kprobes-based tracing events
   4  *
   5  * Created by Masami Hiramatsu <mhiramat@redhat.com>
   6  *
   7  */
   8 #define pr_fmt(fmt)     "trace_kprobe: " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/rculist.h>
  13 #include <linux/error-injection.h>
  14
  15 #include "trace_kprobe_selftest.h"
  16 #include "trace_probe.h"
  17
  18 #define KPROBE_EVENT_SYSTEM "kprobes"
  19 #define KRETPROBE_MAXACTIVE_MAX 4096
  20
  21 /**
  22  * Kprobe event core functions
  23  */
  24 struct trace_kprobe {
  25         struct list_head        list;
  26         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
  27         unsigned long __percpu *nhit;
  28         const char              *symbol;        /* symbol name */
  29         struct trace_probe      tp;
  30 };
  31
  32 #define SIZEOF_TRACE_KPROBE(n)                          \
  33         (offsetof(struct trace_kprobe, tp.args) +       \
  34         (sizeof(struct probe_arg) * (n)))
  35
  36 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
  37 {
  38         return tk->rp.handler != NULL;
  39 }
  40
  41 static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
  42 {
  43         return tk->symbol ? tk->symbol : "unknown";
  44 }
  45
  46 static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
  47 {
  48         return tk->rp.kp.offset;
  49 }
  50
  51 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
  52 {
  53         return !!(kprobe_gone(&tk->rp.kp));
  54 }
  55
  56 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
  57                                                  struct module *mod)
  58 {
  59         int len = strlen(mod->name);
  60         const char *name = trace_kprobe_symbol(tk);
  61         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
  62 }
  63
  64 static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)
  65 {
  66         return !!strchr(trace_kprobe_symbol(tk), ':');
  67 }
  68
  69 static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
  70 {
  71         unsigned long nhit = 0;
  72         int cpu;
  73
  74         for_each_possible_cpu(cpu)
  75                 nhit += *per_cpu_ptr(tk->nhit, cpu);
  76
  77         return nhit;
  78 }
  79
  80 /* Return 0 if it fails to find the symbol address */
  81 static nokprobe_inline
  82 unsigned long trace_kprobe_address(struct trace_kprobe *tk)
  83 {
  84         unsigned long addr;
  85
  86         if (tk->symbol) {
  87                 addr = (unsigned long)
  88                         kallsyms_lookup_name(trace_kprobe_symbol(tk));
  89                 if (addr)
  90                         addr += tk->rp.kp.offset;
  91         } else {
  92                 addr = (unsigned long)tk->rp.kp.addr;
  93         }
  94         return addr;
  95 }
  96
  97 bool trace_kprobe_on_func_entry(struct trace_event_call *call)
  98 {
  99         struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
 100
 101         return kprobe_on_func_entry(tk->rp.kp.addr,
 102                         tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
 103                         tk->rp.kp.addr ? 0 : tk->rp.kp.offset);
 104 }
 105
 106 bool trace_kprobe_error_injectable(struct trace_event_call *call)
 107 {
 108         struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
 109
 110         return within_error_injection_list(trace_kprobe_address(tk));
 111 }
 112
 113 static int register_kprobe_event(struct trace_kprobe *tk);
 114 static int unregister_kprobe_event(struct trace_kprobe *tk);
 115
 116 static DEFINE_MUTEX(probe_lock);
 117 static LIST_HEAD(probe_list);
 118
 119 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 120 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 121                                 struct pt_regs *regs);
 122
 123 /* Memory fetching by symbol */
 124 struct symbol_cache {
 125         char            *symbol;
 126         long            offset;
 127         unsigned long   addr;
 128 };
 129
 130 unsigned long update_symbol_cache(struct symbol_cache *sc)
 131 {
 132         sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
 133
 134         if (sc->addr)
 135                 sc->addr += sc->offset;
 136
 137         return sc->addr;
 138 }
 139
 140 void free_symbol_cache(struct symbol_cache *sc)
 141 {
 142         kfree(sc->symbol);
 143         kfree(sc);
 144 }
 145
 146 struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
 147 {
 148         struct symbol_cache *sc;
 149
 150         if (!sym || strlen(sym) == 0)
 151                 return NULL;
 152
 153         sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
 154         if (!sc)
 155                 return NULL;
 156
 157         sc->symbol = kstrdup(sym, GFP_KERNEL);
 158         if (!sc->symbol) {
 159                 kfree(sc);
 160                 return NULL;
 161         }
 162         sc->offset = offset;
 163         update_symbol_cache(sc);
 164
 165         return sc;
 166 }
 167
 168 /*
 169  * Kprobes-specific fetch functions
 170  */
 171 #define DEFINE_FETCH_stack(type)                                        \
 172 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
 173                                           void *offset, void *dest)     \
 174 {                                                                       \
 175         *(type *)dest = (type)regs_get_kernel_stack_nth(regs,           \
 176                                 (unsigned int)((unsigned long)offset)); \
 177 }                                                                       \
 178 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
 179
 180 DEFINE_BASIC_FETCH_FUNCS(stack)
 181 /* No string on the stack entry */
 182 #define fetch_stack_string      NULL
 183 #define fetch_stack_string_size NULL
 184
 185 #define DEFINE_FETCH_memory(type)                                       \
 186 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
 187                                           void *addr, void *dest)       \
 188 {                                                                       \
 189         type retval;                                                    \
 190         if (probe_kernel_address(addr, retval))                         \
 191                 *(type *)dest = 0;                                      \
 192         else                                                            \
 193                 *(type *)dest = retval;                                 \
 194 }                                                                       \
 195 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
 196
 197 DEFINE_BASIC_FETCH_FUNCS(memory)
 198 /*
 199  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 200  * length and relative data location.
 201  */
 202 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
 203                                             void *addr, void *dest)
 204 {
 205         int maxlen = get_rloc_len(*(u32 *)dest);
 206         u8 *dst = get_rloc_data(dest);
 207         long ret;
 208
 209         if (!maxlen)
 210                 return;
 211
 212         /*
 213          * Try to get string again, since the string can be changed while
 214          * probing.
 215          */
 216         ret = strncpy_from_unsafe(dst, addr, maxlen);
 217
 218         if (ret < 0) {  /* Failed to fetch string */
 219                 dst[0] = '\0';
 220                 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
 221         } else {
 222                 *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
 223         }
 224 }
 225 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
 226
 227 /* Return the length of string -- including null terminal byte */
 228 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 229                                                  void *addr, void *dest)
 230 {
 231         mm_segment_t old_fs;
 232         int ret, len = 0;
 233         u8 c;
 234
 235         old_fs = get_fs();
 236         set_fs(KERNEL_DS);
 237         pagefault_disable();
 238
 239         do {
 240                 ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
 241                 len++;
 242         } while (c && ret == 0 && len < MAX_STRING_SIZE);
 243
 244         pagefault_enable();
 245         set_fs(old_fs);
 246
 247         if (ret < 0)    /* Failed to check the length */
 248                 *(u32 *)dest = 0;
 249         else
 250                 *(u32 *)dest = len;
 251 }
 252 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
 253
 254 #define DEFINE_FETCH_symbol(type)                                       \
 255 void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
 256 {                                                                       \
 257         struct symbol_cache *sc = data;                                 \
 258         if (sc->addr)                                                   \
 259                 fetch_memory_##type(regs, (void *)sc->addr, dest);      \
 260         else                                                            \
 261                 *(type *)dest = 0;                                      \
 262 }                                                                       \
 263 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
 264
 265 DEFINE_BASIC_FETCH_FUNCS(symbol)
 266 DEFINE_FETCH_symbol(string)
 267 DEFINE_FETCH_symbol(string_size)
 268
 269 /* kprobes don't support file_offset fetch methods */
 270 #define fetch_file_offset_u8            NULL
 271 #define fetch_file_offset_u16           NULL
 272 #define fetch_file_offset_u32           NULL
 273 #define fetch_file_offset_u64           NULL
 274 #define fetch_file_offset_string        NULL
 275 #define fetch_file_offset_string_size   NULL
 276
 277 /* Fetch type information table */
 278 static const struct fetch_type kprobes_fetch_type_table[] = {
 279         /* Special types */
 280         [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
 281                                         sizeof(u32), 1, "__data_loc char[]"),
 282         [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
 283                                         string_size, sizeof(u32), 0, "u32"),
 284         /* Basic types */
 285         ASSIGN_FETCH_TYPE(u8,  u8,  0),
 286         ASSIGN_FETCH_TYPE(u16, u16, 0),
 287         ASSIGN_FETCH_TYPE(u32, u32, 0),
 288         ASSIGN_FETCH_TYPE(u64, u64, 0),
 289         ASSIGN_FETCH_TYPE(s8,  u8,  1),
 290         ASSIGN_FETCH_TYPE(s16, u16, 1),
 291         ASSIGN_FETCH_TYPE(s32, u32, 1),
 292         ASSIGN_FETCH_TYPE(s64, u64, 1),
 293         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
 294         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 295         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 296         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
 297
 298         ASSIGN_FETCH_TYPE_END
 299 };
 300
 301 /*
 302  * Allocate new trace_probe and initialize it (including kprobes).
 303  */
 304 static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 305                                              const char *event,
 306                                              void *addr,
 307                                              const char *symbol,
 308                                              unsigned long offs,
 309                                              int maxactive,
 310                                              int nargs, bool is_return)
 311 {
 312         struct trace_kprobe *tk;
 313         int ret = -ENOMEM;
 314
 315         tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
 316         if (!tk)
 317                 return ERR_PTR(ret);
 318
 319         tk->nhit = alloc_percpu(unsigned long);
 320         if (!tk->nhit)
 321                 goto error;
 322
 323         if (symbol) {
 324                 tk->symbol = kstrdup(symbol, GFP_KERNEL);
 325                 if (!tk->symbol)
 326                         goto error;
 327                 tk->rp.kp.symbol_name = tk->symbol;
 328                 tk->rp.kp.offset = offs;
 329         } else
 330                 tk->rp.kp.addr = addr;
 331
 332         if (is_return)
 333                 tk->rp.handler = kretprobe_dispatcher;
 334         else
 335                 tk->rp.kp.pre_handler = kprobe_dispatcher;
 336
 337         tk->rp.maxactive = maxactive;
 338
 339         if (!event || !is_good_name(event)) {
 340                 ret = -EINVAL;
 341                 goto error;
 342         }
 343
 344         tk->tp.call.class = &tk->tp.class;
 345         tk->tp.call.name = kstrdup(event, GFP_KERNEL);
 346         if (!tk->tp.call.name)
 347                 goto error;
 348
 349         if (!group || !is_good_name(group)) {
 350                 ret = -EINVAL;
 351                 goto error;
 352         }
 353
 354         tk->tp.class.system = kstrdup(group, GFP_KERNEL);
 355         if (!tk->tp.class.system)
 356                 goto error;
 357
 358         INIT_LIST_HEAD(&tk->list);
 359         INIT_LIST_HEAD(&tk->tp.files);
 360         return tk;
 361 error:
 362         kfree(tk->tp.call.name);
 363         kfree(tk->symbol);
 364         free_percpu(tk->nhit);
 365         kfree(tk);
 366         return ERR_PTR(ret);
 367 }
 368
 369 static void free_trace_kprobe(struct trace_kprobe *tk)
 370 {
 371         int i;
 372
 373         for (i = 0; i < tk->tp.nr_args; i++)
 374                 traceprobe_free_probe_arg(&tk->tp.args[i]);
 375
 376         kfree(tk->tp.call.class->system);
 377         kfree(tk->tp.call.name);
 378         kfree(tk->symbol);
 379         free_percpu(tk->nhit);
 380         kfree(tk);
 381 }
 382
 383 static struct trace_kprobe *find_trace_kprobe(const char *event,
 384                                               const char *group)
 385 {
 386         struct trace_kprobe *tk;
 387
 388         list_for_each_entry(tk, &probe_list, list)
 389                 if (strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
 390                     strcmp(tk->tp.call.class->system, group) == 0)
 391                         return tk;
 392         return NULL;
 393 }
 394
 395 static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
 396 {
 397         int ret = 0;
 398
 399         if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
 400                 if (trace_kprobe_is_return(tk))
 401                         ret = enable_kretprobe(&tk->rp);
 402                 else
 403                         ret = enable_kprobe(&tk->rp.kp);
 404         }
 405
 406         return ret;
 407 }
 408
 409 /*
 410  * Enable trace_probe
 411  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
 412  */
 413 static int
 414 enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 415 {
 416         struct event_file_link *link;
 417         int ret = 0;
 418
 419         if (file) {
 420                 link = kmalloc(sizeof(*link), GFP_KERNEL);
 421                 if (!link) {
 422                         ret = -ENOMEM;
 423                         goto out;
 424                 }
 425
 426                 link->file = file;
 427                 list_add_tail_rcu(&link->list, &tk->tp.files);
 428
 429                 tk->tp.flags |= TP_FLAG_TRACE;
 430                 ret = __enable_trace_kprobe(tk);
 431                 if (ret) {
 432                         list_del_rcu(&link->list);
 433                         kfree(link);
 434                         tk->tp.flags &= ~TP_FLAG_TRACE;
 435                 }
 436
 437         } else {
 438                 tk->tp.flags |= TP_FLAG_PROFILE;
 439                 ret = __enable_trace_kprobe(tk);
 440                 if (ret)
 441                         tk->tp.flags &= ~TP_FLAG_PROFILE;
 442         }
 443  out:
 444         return ret;
 445 }
 446
 447 /*
 448  * Disable trace_probe
 449  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
 450  */
 451 static int
 452 disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 453 {
 454         struct event_file_link *link = NULL;
 455         int wait = 0;
 456         int ret = 0;
 457
 458         if (file) {
 459                 link = find_event_file_link(&tk->tp, file);
 460                 if (!link) {
 461                         ret = -EINVAL;
 462                         goto out;
 463                 }
 464
 465                 list_del_rcu(&link->list);
 466                 wait = 1;
 467                 if (!list_empty(&tk->tp.files))
 468                         goto out;
 469
 470                 tk->tp.flags &= ~TP_FLAG_TRACE;
 471         } else
 472                 tk->tp.flags &= ~TP_FLAG_PROFILE;
 473
 474         if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
 475                 if (trace_kprobe_is_return(tk))
 476                         disable_kretprobe(&tk->rp);
 477                 else
 478                         disable_kprobe(&tk->rp.kp);
 479                 wait = 1;
 480         }
 481
 482         /*
 483          * if tk is not added to any list, it must be a local trace_kprobe
 484          * created with perf_event_open. We don't need to wait for these
 485          * trace_kprobes
 486          */
 487         if (list_empty(&tk->list))
 488                 wait = 0;
 489  out:
 490         if (wait) {
 491                 /*
 492                  * Synchronize with kprobe_trace_func/kretprobe_trace_func
 493                  * to ensure disabled (all running handlers are finished).
 494                  * This is not only for kfree(), but also the caller,
 495                  * trace_remove_event_call() supposes it for releasing
 496                  * event_call related objects, which will be accessed in
 497                  * the kprobe_trace_func/kretprobe_trace_func.
 498                  */
 499                 synchronize_sched();
 500                 kfree(link);    /* Ignored if link == NULL */
 501         }
 502
 503         return ret;
 504 }
 505
 506 #if defined(CONFIG_KPROBES_ON_FTRACE) && \
 507         !defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
 508 static bool within_notrace_func(struct trace_kprobe *tk)
 509 {
 510         unsigned long offset, size, addr;
 511
 512         addr = trace_kprobe_address(tk);
 513         if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))
 514                 return false;
 515
 516         /* Get the entry address of the target function */
 517         addr -= offset;
 518
 519         /*
 520          * Since ftrace_location_range() does inclusive range check, we need
 521          * to subtract 1 byte from the end address.
 522          */
 523         return !ftrace_location_range(addr, addr + size - 1);
 524 }
 525 #else
 526 #define within_notrace_func(tk) (false)
 527 #endif
 528
 529 /* Internal register function - just handle k*probes and flags */
 530 static int __register_trace_kprobe(struct trace_kprobe *tk)
 531 {
 532         int i, ret;
 533
 534         if (trace_probe_is_registered(&tk->tp))
 535                 return -EINVAL;
 536
 537         if (within_notrace_func(tk)) {
 538                 pr_warn("Could not probe notrace function %s\n",
 539                         trace_kprobe_symbol(tk));
 540                 return -EINVAL;
 541         }
 542
 543         for (i = 0; i < tk->tp.nr_args; i++)
 544                 traceprobe_update_arg(&tk->tp.args[i]);
 545
 546         /* Set/clear disabled flag according to tp->flag */
 547         if (trace_probe_is_enabled(&tk->tp))
 548                 tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
 549         else
 550                 tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
 551
 552         if (trace_kprobe_is_return(tk))
 553                 ret = register_kretprobe(&tk->rp);
 554         else
 555                 ret = register_kprobe(&tk->rp.kp);
 556
 557         if (ret == 0)
 558                 tk->tp.flags |= TP_FLAG_REGISTERED;
 559         else {
 560                 if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
 561                         pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
 562                         ret = 0;
 563                 } else if (ret == -EILSEQ) {
 564                         pr_warn("Probing address(0x%p) is not an instruction boundary.\n",
 565                                 tk->rp.kp.addr);
 566                         ret = -EINVAL;
 567                 }
 568         }
 569
 570         return ret;
 571 }
 572
 573 /* Internal unregister function - just handle k*probes and flags */
 574 static void __unregister_trace_kprobe(struct trace_kprobe *tk)
 575 {
 576         if (trace_probe_is_registered(&tk->tp)) {
 577                 if (trace_kprobe_is_return(tk))
 578                         unregister_kretprobe(&tk->rp);
 579                 else
 580                         unregister_kprobe(&tk->rp.kp);
 581                 tk->tp.flags &= ~TP_FLAG_REGISTERED;
 582                 /* Cleanup kprobe for reuse */
 583                 if (tk->rp.kp.symbol_name)
 584                         tk->rp.kp.addr = NULL;
 585         }
 586 }
 587
 588 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
 589 static int unregister_trace_kprobe(struct trace_kprobe *tk)
 590 {
 591         /* Enabled event can not be unregistered */
 592         if (trace_probe_is_enabled(&tk->tp))
 593                 return -EBUSY;
 594
 595         /* Will fail if probe is being used by ftrace or perf */
 596         if (unregister_kprobe_event(tk))
 597                 return -EBUSY;
 598
 599         __unregister_trace_kprobe(tk);
 600         list_del(&tk->list);
 601
 602         return 0;
 603 }
 604
 605 /* Register a trace_probe and probe_event */
 606 static int register_trace_kprobe(struct trace_kprobe *tk)
 607 {
 608         struct trace_kprobe *old_tk;
 609         int ret;
 610
 611         mutex_lock(&probe_lock);
 612
 613         /* Delete old (same name) event if exist */
 614         old_tk = find_trace_kprobe(trace_event_name(&tk->tp.call),
 615                         tk->tp.call.class->system);
 616         if (old_tk) {
 617                 ret = unregister_trace_kprobe(old_tk);
 618                 if (ret < 0)
 619                         goto end;
 620                 free_trace_kprobe(old_tk);
 621         }
 622
 623         /* Register new event */
 624         ret = register_kprobe_event(tk);
 625         if (ret) {
 626                 pr_warn("Failed to register probe event(%d)\n", ret);
 627                 goto end;
 628         }
 629
 630         /* Register k*probe */
 631         ret = __register_trace_kprobe(tk);
 632         if (ret < 0)
 633                 unregister_kprobe_event(tk);
 634         else
 635                 list_add_tail(&tk->list, &probe_list);
 636
 637 end:
 638         mutex_unlock(&probe_lock);
 639         return ret;
 640 }
 641
 642 /* Module notifier call back, checking event on the module */
 643 static int trace_kprobe_module_callback(struct notifier_block *nb,
 644                                        unsigned long val, void *data)
 645 {
 646         struct module *mod = data;
 647         struct trace_kprobe *tk;
 648         int ret;
 649
 650         if (val != MODULE_STATE_COMING)
 651                 return NOTIFY_DONE;
 652
 653         /* Update probes on coming module */
 654         mutex_lock(&probe_lock);
 655         list_for_each_entry(tk, &probe_list, list) {
 656                 if (trace_kprobe_within_module(tk, mod)) {
 657                         /* Don't need to check busy - this should have gone. */
 658                         __unregister_trace_kprobe(tk);
 659                         ret = __register_trace_kprobe(tk);
 660                         if (ret)
 661                                 pr_warn("Failed to re-register probe %s on %s: %d\n",
 662                                         trace_event_name(&tk->tp.call),
 663                                         mod->name, ret);
 664                 }
 665         }
 666         mutex_unlock(&probe_lock);
 667
 668         return NOTIFY_DONE;
 669 }
 670
 671 static struct notifier_block trace_kprobe_module_nb = {
 672         .notifier_call = trace_kprobe_module_callback,
 673         .priority = 1   /* Invoked after kprobe module callback */
 674 };
 675
 676 /* Convert certain expected symbols into '_' when generating event names */
 677 static inline void sanitize_event_name(char *name)
 678 {
 679         while (*name++ != '\0')
 680                 if (*name == ':' || *name == '.')
 681                         *name = '_';
 682 }
 683
 684 static int create_trace_kprobe(int argc, char **argv)
 685 {
 686         /*
 687          * Argument syntax:
 688          *  - Add kprobe:
 689          *      p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
 690          *  - Add kretprobe:
 691          *      r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
 692          * Fetch args:
 693          *  $retval     : fetch return value
 694          *  $stack      : fetch stack address
 695          *  $stackN     : fetch Nth of stack (N:0-)
 696          *  $comm       : fetch current task comm
 697          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
 698          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 699          *  %REG        : fetch register REG
 700          * Dereferencing memory fetch:
 701          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
 702          * Alias name of args:
 703          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
 704          * Type of args:
 705          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 706          */
 707         struct trace_kprobe *tk;
 708         int i, ret = 0;
 709         bool is_return = false, is_delete = false;
 710         char *symbol = NULL, *event = NULL, *group = NULL;
 711         int maxactive = 0;
 712         char *arg;
 713         long offset = 0;
 714         void *addr = NULL;
 715         char buf[MAX_EVENT_NAME_LEN];
 716
 717         /* argc must be >= 1 */
 718         if (argv[0][0] == 'p')
 719                 is_return = false;
 720         else if (argv[0][0] == 'r')
 721                 is_return = true;
 722         else if (argv[0][0] == '-')
 723                 is_delete = true;
 724         else {
 725                 pr_info("Probe definition must be started with 'p', 'r' or"
 726                         " '-'.\n");
 727                 return -EINVAL;
 728         }
 729
 730         event = strchr(&argv[0][1], ':');
 731         if (event) {
 732                 event[0] = '\0';
 733                 event++;
 734         }
 735         if (is_return && isdigit(argv[0][1])) {
 736                 ret = kstrtouint(&argv[0][1], 0, &maxactive);
 737                 if (ret) {
 738                         pr_info("Failed to parse maxactive.\n");
 739                         return ret;
 740                 }
 741                 /* kretprobes instances are iterated over via a list. The
 742                  * maximum should stay reasonable.
 743                  */
 744                 if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
 745                         pr_info("Maxactive is too big (%d > %d).\n",
 746                                 maxactive, KRETPROBE_MAXACTIVE_MAX);
 747                         return -E2BIG;
 748                 }
 749         }
 750
 751         if (event) {
 752                 if (strchr(event, '/')) {
 753                         group = event;
 754                         event = strchr(group, '/') + 1;
 755                         event[-1] = '\0';
 756                         if (strlen(group) == 0) {
 757                                 pr_info("Group name is not specified\n");
 758                                 return -EINVAL;
 759                         }
 760                 }
 761                 if (strlen(event) == 0) {
 762                         pr_info("Event name is not specified\n");
 763                         return -EINVAL;
 764                 }
 765         }
 766         if (!group)
 767                 group = KPROBE_EVENT_SYSTEM;
 768
 769         if (is_delete) {
 770                 if (!event) {
 771                         pr_info("Delete command needs an event name.\n");
 772                         return -EINVAL;
 773                 }
 774                 mutex_lock(&probe_lock);
 775                 tk = find_trace_kprobe(event, group);
 776                 if (!tk) {
 777                         mutex_unlock(&probe_lock);
 778                         pr_info("Event %s/%s doesn't exist.\n", group, event);
 779                         return -ENOENT;
 780                 }
 781                 /* delete an event */
 782                 ret = unregister_trace_kprobe(tk);
 783                 if (ret == 0)
 784                         free_trace_kprobe(tk);
 785                 mutex_unlock(&probe_lock);
 786                 return ret;
 787         }
 788
 789         if (argc < 2) {
 790                 pr_info("Probe point is not specified.\n");
 791                 return -EINVAL;
 792         }
 793
 794         /* try to parse an address. if that fails, try to read the
 795          * input as a symbol. */
 796         if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
 797                 /* a symbol specified */
 798                 symbol = argv[1];
 799                 /* TODO: support .init module functions */
 800                 ret = traceprobe_split_symbol_offset(symbol, &offset);
 801                 if (ret || offset < 0 || offset > UINT_MAX) {
 802                         pr_info("Failed to parse either an address or a symbol.\n");
 803                         return ret;
 804                 }
 805                 if (offset && is_return &&
 806                     !kprobe_on_func_entry(NULL, symbol, offset)) {
 807                         pr_info("Given offset is not valid for return probe.\n");
 808                         return -EINVAL;
 809                 }
 810         }
 811         argc -= 2; argv += 2;
 812
 813         /* setup a probe */
 814         if (!event) {
 815                 /* Make a new event name */
 816                 if (symbol)
 817                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
 818                                  is_return ? 'r' : 'p', symbol, offset);
 819                 else
 820                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
 821                                  is_return ? 'r' : 'p', addr);
 822                 sanitize_event_name(buf);
 823                 event = buf;
 824         }
 825         tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
 826                                argc, is_return);
 827         if (IS_ERR(tk)) {
 828                 pr_info("Failed to allocate trace_probe.(%d)\n",
 829                         (int)PTR_ERR(tk));
 830                 return PTR_ERR(tk);
 831         }
 832
 833         /* parse arguments */
 834         ret = 0;
 835         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
 836                 struct probe_arg *parg = &tk->tp.args[i];
 837
 838                 /* Increment count for freeing args in error case */
 839                 tk->tp.nr_args++;
 840
 841                 /* Parse argument name */
 842                 arg = strchr(argv[i], '=');
 843                 if (arg) {
 844                         *arg++ = '\0';
 845                         parg->name = kstrdup(argv[i], GFP_KERNEL);
 846                 } else {
 847                         arg = argv[i];
 848                         /* If argument name is omitted, set "argN" */
 849                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
 850                         parg->name = kstrdup(buf, GFP_KERNEL);
 851                 }
 852
 853                 if (!parg->name) {
 854                         pr_info("Failed to allocate argument[%d] name.\n", i);
 855                         ret = -ENOMEM;
 856                         goto error;
 857                 }
 858
 859                 if (!is_good_name(parg->name)) {
 860                         pr_info("Invalid argument[%d] name: %s\n",
 861                                 i, parg->name);
 862                         ret = -EINVAL;
 863                         goto error;
 864                 }
 865
 866                 if (traceprobe_conflict_field_name(parg->name,
 867                                                         tk->tp.args, i)) {
 868                         pr_info("Argument[%d] name '%s' conflicts with "
 869                                 "another field.\n", i, argv[i]);
 870                         ret = -EINVAL;
 871                         goto error;
 872                 }
 873
 874                 /* Parse fetch argument */
 875                 ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
 876                                                 is_return, true,
 877                                                 kprobes_fetch_type_table);
 878                 if (ret) {
 879                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 880                         goto error;
 881                 }
 882         }
 883
 884         ret = register_trace_kprobe(tk);
 885         if (ret)
 886                 goto error;
 887         return 0;
 888
 889 error:
 890         free_trace_kprobe(tk);
 891         return ret;
 892 }
 893
 894 static int release_all_trace_kprobes(void)
 895 {
 896         struct trace_kprobe *tk;
 897         int ret = 0;
 898
 899         mutex_lock(&probe_lock);
 900         /* Ensure no probe is in use. */
 901         list_for_each_entry(tk, &probe_list, list)
 902                 if (trace_probe_is_enabled(&tk->tp)) {
 903                         ret = -EBUSY;
 904                         goto end;
 905                 }
 906         /* TODO: Use batch unregistration */
 907         while (!list_empty(&probe_list)) {
 908                 tk = list_entry(probe_list.next, struct trace_kprobe, list);
 909                 ret = unregister_trace_kprobe(tk);
 910                 if (ret)
 911                         goto end;
 912                 free_trace_kprobe(tk);
 913         }
 914
 915 end:
 916         mutex_unlock(&probe_lock);
 917
 918         return ret;
 919 }
 920
 921 /* Probes listing interfaces */
 922 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
 923 {
 924         mutex_lock(&probe_lock);
 925         return seq_list_start(&probe_list, *pos);
 926 }
 927
 928 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
 929 {
 930         return seq_list_next(v, &probe_list, pos);
 931 }
 932
 933 static void probes_seq_stop(struct seq_file *m, void *v)
 934 {
 935         mutex_unlock(&probe_lock);
 936 }
 937
 938 static int probes_seq_show(struct seq_file *m, void *v)
 939 {
 940         struct trace_kprobe *tk = v;
 941         int i;
 942
 943         seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
 944         seq_printf(m, ":%s/%s", tk->tp.call.class->system,
 945                         trace_event_name(&tk->tp.call));
 946
 947         if (!tk->symbol)
 948                 seq_printf(m, " 0x%p", tk->rp.kp.addr);
 949         else if (tk->rp.kp.offset)
 950                 seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
 951                            tk->rp.kp.offset);
 952         else
 953                 seq_printf(m, " %s", trace_kprobe_symbol(tk));
 954
 955         for (i = 0; i < tk->tp.nr_args; i++)
 956                 seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
 957         seq_putc(m, '\n');
 958
 959         return 0;
 960 }
 961
 962 static const struct seq_operations probes_seq_op = {
 963         .start  = probes_seq_start,
 964         .next   = probes_seq_next,
 965         .stop   = probes_seq_stop,
 966         .show   = probes_seq_show
 967 };
 968
 969 static int probes_open(struct inode *inode, struct file *file)
 970 {
 971         int ret;
 972
 973         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 974                 ret = release_all_trace_kprobes();
 975                 if (ret < 0)
 976                         return ret;
 977         }
 978
 979         return seq_open(file, &probes_seq_op);
 980 }
 981
 982 static ssize_t probes_write(struct file *file, const char __user *buffer,
 983                             size_t count, loff_t *ppos)
 984 {
 985         return trace_parse_run_command(file, buffer, count, ppos,
 986                                        create_trace_kprobe);
 987 }
 988
 989 static const struct file_operations kprobe_events_ops = {
 990         .owner          = THIS_MODULE,
 991         .open           = probes_open,
 992         .read           = seq_read,
 993         .llseek         = seq_lseek,
 994         .release        = seq_release,
 995         .write          = probes_write,
 996 };
 997
 998 /* Probes profiling interfaces */
 999 static int probes_profile_seq_show(struct seq_file *m, void *v)
1000 {
1001         struct trace_kprobe *tk = v;
1002
1003         seq_printf(m, "  %-44s %15lu %15lu\n",
1004                    trace_event_name(&tk->tp.call),
1005                    trace_kprobe_nhit(tk),
1006                    tk->rp.kp.nmissed);
1007
1008         return 0;
1009 }
1010
1011 static const struct seq_operations profile_seq_op = {
1012         .start  = probes_seq_start,
1013         .next   = probes_seq_next,
1014         .stop   = probes_seq_stop,
1015         .show   = probes_profile_seq_show
1016 };
1017
1018 static int profile_open(struct inode *inode, struct file *file)
1019 {
1020         return seq_open(file, &profile_seq_op);
1021 }
1022
1023 static const struct file_operations kprobe_profile_ops = {
1024         .owner          = THIS_MODULE,
1025         .open           = profile_open,
1026         .read           = seq_read,
1027         .llseek         = seq_lseek,
1028         .release        = seq_release,
1029 };
1030
1031 /* Kprobe handler */
1032 static nokprobe_inline void
1033 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
1034                     struct trace_event_file *trace_file)
1035 {
1036         struct kprobe_trace_entry_head *entry;
1037         struct ring_buffer_event *event;
1038         struct ring_buffer *buffer;
1039         int size, dsize, pc;
1040         unsigned long irq_flags;
1041         struct trace_event_call *call = &tk->tp.call;
1042
1043         WARN_ON(call != trace_file->event_call);
1044
1045         if (trace_trigger_soft_disabled(trace_file))
1046                 return;
1047
1048         local_save_flags(irq_flags);
1049         pc = preempt_count();
1050
1051         dsize = __get_data_size(&tk->tp, regs);
1052         size = sizeof(*entry) + tk->tp.size + dsize;
1053
1054         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1055                                                 call->event.type,
1056                                                 size, irq_flags, pc);
1057         if (!event)
1058                 return;
1059
1060         entry = ring_buffer_event_data(event);
1061         entry->ip = (unsigned long)tk->rp.kp.addr;
1062         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1063
1064         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1065                                          entry, irq_flags, pc, regs);
1066 }
1067
1068 static void
1069 kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
1070 {
1071         struct event_file_link *link;
1072
1073         list_for_each_entry_rcu(link, &tk->tp.files, list)
1074                 __kprobe_trace_func(tk, regs, link->file);
1075 }
1076 NOKPROBE_SYMBOL(kprobe_trace_func);
1077
1078 /* Kretprobe handler */
1079 static nokprobe_inline void
1080 __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1081                        struct pt_regs *regs,
1082                        struct trace_event_file *trace_file)
1083 {
1084         struct kretprobe_trace_entry_head *entry;
1085         struct ring_buffer_event *event;
1086         struct ring_buffer *buffer;
1087         int size, pc, dsize;
1088         unsigned long irq_flags;
1089         struct trace_event_call *call = &tk->tp.call;
1090
1091         WARN_ON(call != trace_file->event_call);
1092
1093         if (trace_trigger_soft_disabled(trace_file))
1094                 return;
1095
1096         local_save_flags(irq_flags);
1097         pc = preempt_count();
1098
1099         dsize = __get_data_size(&tk->tp, regs);
1100         size = sizeof(*entry) + tk->tp.size + dsize;
1101
1102         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1103                                                 call->event.type,
1104                                                 size, irq_flags, pc);
1105         if (!event)
1106                 return;
1107
1108         entry = ring_buffer_event_data(event);
1109         entry->func = (unsigned long)tk->rp.kp.addr;
1110         entry->ret_ip = (unsigned long)ri->ret_addr;
1111         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1112
1113         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1114                                          entry, irq_flags, pc, regs);
1115 }
1116
1117 static void
1118 kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1119                      struct pt_regs *regs)
1120 {
1121         struct event_file_link *link;
1122
1123         list_for_each_entry_rcu(link, &tk->tp.files, list)
1124                 __kretprobe_trace_func(tk, ri, regs, link->file);
1125 }
1126 NOKPROBE_SYMBOL(kretprobe_trace_func);
1127
1128 /* Event entry printers */
1129 static enum print_line_t
1130 print_kprobe_event(struct trace_iterator *iter, int flags,
1131                    struct trace_event *event)
1132 {
1133         struct kprobe_trace_entry_head *field;
1134         struct trace_seq *s = &iter->seq;
1135         struct trace_probe *tp;
1136         u8 *data;
1137         int i;
1138
1139         field = (struct kprobe_trace_entry_head *)iter->ent;
1140         tp = container_of(event, struct trace_probe, call.event);
1141
1142         trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
1143
1144         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
1145                 goto out;
1146
1147         trace_seq_putc(s, ')');
1148
1149         data = (u8 *)&field[1];
1150         for (i = 0; i < tp->nr_args; i++)
1151                 if (!tp->args[i].type->print(s, tp->args[i].name,
1152                                              data + tp->args[i].offset, field))
1153                         goto out;
1154
1155         trace_seq_putc(s, '\n');
1156  out:
1157         return trace_handle_return(s);
1158 }
1159
1160 static enum print_line_t
1161 print_kretprobe_event(struct trace_iterator *iter, int flags,
1162                       struct trace_event *event)
1163 {
1164         struct kretprobe_trace_entry_head *field;
1165         struct trace_seq *s = &iter->seq;
1166         struct trace_probe *tp;
1167         u8 *data;
1168         int i;
1169
1170         field = (struct kretprobe_trace_entry_head *)iter->ent;
1171         tp = container_of(event, struct trace_probe, call.event);
1172
1173         trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
1174
1175         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
1176                 goto out;
1177
1178         trace_seq_puts(s, " <- ");
1179
1180         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
1181                 goto out;
1182
1183         trace_seq_putc(s, ')');
1184
1185         data = (u8 *)&field[1];
1186         for (i = 0; i < tp->nr_args; i++)
1187                 if (!tp->args[i].type->print(s, tp->args[i].name,
1188                                              data + tp->args[i].offset, field))
1189                         goto out;
1190
1191         trace_seq_putc(s, '\n');
1192
1193  out:
1194         return trace_handle_return(s);
1195 }
1196
1197
1198 static int kprobe_event_define_fields(struct trace_event_call *event_call)
1199 {
1200         int ret, i;
1201         struct kprobe_trace_entry_head field;
1202         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1203
1204         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
1205         /* Set argument names as fields */
1206         for (i = 0; i < tk->tp.nr_args; i++) {
1207                 struct probe_arg *parg = &tk->tp.args[i];
1208
1209                 ret = trace_define_field(event_call, parg->type->fmttype,
1210                                          parg->name,
1211                                          sizeof(field) + parg->offset,
1212                                          parg->type->size,
1213                                          parg->type->is_signed,
1214                                          FILTER_OTHER);
1215                 if (ret)
1216                         return ret;
1217         }
1218         return 0;
1219 }
1220
1221 static int kretprobe_event_define_fields(struct trace_event_call *event_call)
1222 {
1223         int ret, i;
1224         struct kretprobe_trace_entry_head field;
1225         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1226
1227         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1228         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1229         /* Set argument names as fields */
1230         for (i = 0; i < tk->tp.nr_args; i++) {
1231                 struct probe_arg *parg = &tk->tp.args[i];
1232
1233                 ret = trace_define_field(event_call, parg->type->fmttype,
1234                                          parg->name,
1235                                          sizeof(field) + parg->offset,
1236                                          parg->type->size,
1237                                          parg->type->is_signed,
1238                                          FILTER_OTHER);
1239                 if (ret)
1240                         return ret;
1241         }
1242         return 0;
1243 }
1244
1245 #ifdef CONFIG_PERF_EVENTS
1246
1247 /* Kprobe profile handler */
1248 static int
1249 kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
1250 {
1251         struct trace_event_call *call = &tk->tp.call;
1252         struct kprobe_trace_entry_head *entry;
1253         struct hlist_head *head;
1254         int size, __size, dsize;
1255         int rctx;
1256
1257         if (bpf_prog_array_valid(call)) {
1258                 unsigned long orig_ip = instruction_pointer(regs);
1259                 int ret;
1260
1261                 ret = trace_call_bpf(call, regs);
1262
1263                 /*
1264                  * We need to check and see if we modified the pc of the
1265                  * pt_regs, and if so return 1 so that we don't do the
1266                  * single stepping.
1267                  */
1268                 if (orig_ip != instruction_pointer(regs))
1269                         return 1;
1270                 if (!ret)
1271                         return 0;
1272         }
1273
1274         head = this_cpu_ptr(call->perf_events);
1275         if (hlist_empty(head))
1276                 return 0;
1277
1278         dsize = __get_data_size(&tk->tp, regs);
1279         __size = sizeof(*entry) + tk->tp.size + dsize;
1280         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1281         size -= sizeof(u32);
1282
1283         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1284         if (!entry)
1285                 return 0;
1286
1287         entry->ip = (unsigned long)tk->rp.kp.addr;
1288         memset(&entry[1], 0, dsize);
1289         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1290         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1291                               head, NULL);
1292         return 0;
1293 }
1294 NOKPROBE_SYMBOL(kprobe_perf_func);
1295
1296 /* Kretprobe profile handler */
1297 static void
1298 kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1299                     struct pt_regs *regs)
1300 {
1301         struct trace_event_call *call = &tk->tp.call;
1302         struct kretprobe_trace_entry_head *entry;
1303         struct hlist_head *head;
1304         int size, __size, dsize;
1305         int rctx;
1306
1307         if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
1308                 return;
1309
1310         head = this_cpu_ptr(call->perf_events);
1311         if (hlist_empty(head))
1312                 return;
1313
1314         dsize = __get_data_size(&tk->tp, regs);
1315         __size = sizeof(*entry) + tk->tp.size + dsize;
1316         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1317         size -= sizeof(u32);
1318
1319         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1320         if (!entry)
1321                 return;
1322
1323         entry->func = (unsigned long)tk->rp.kp.addr;
1324         entry->ret_ip = (unsigned long)ri->ret_addr;
1325         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1326         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1327                               head, NULL);
1328 }
1329 NOKPROBE_SYMBOL(kretprobe_perf_func);
1330
1331 int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
1332                         const char **symbol, u64 *probe_offset,
1333                         u64 *probe_addr, bool perf_type_tracepoint)
1334 {
1335         const char *pevent = trace_event_name(event->tp_event);
1336         const char *group = event->tp_event->class->system;
1337         struct trace_kprobe *tk;
1338
1339         if (perf_type_tracepoint)
1340                 tk = find_trace_kprobe(pevent, group);
1341         else
1342                 tk = event->tp_event->data;
1343         if (!tk)
1344                 return -EINVAL;
1345
1346         *fd_type = trace_kprobe_is_return(tk) ? BPF_FD_TYPE_KRETPROBE
1347                                               : BPF_FD_TYPE_KPROBE;
1348         if (tk->symbol) {
1349                 *symbol = tk->symbol;
1350                 *probe_offset = tk->rp.kp.offset;
1351                 *probe_addr = 0;
1352         } else {
1353                 *symbol = NULL;
1354                 *probe_offset = 0;
1355                 *probe_addr = (unsigned long)tk->rp.kp.addr;
1356         }
1357         return 0;
1358 }
1359 #endif  /* CONFIG_PERF_EVENTS */
1360
1361 /*
1362  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1363  *
1364  * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1365  * lockless, but we can't race with this __init function.
1366  */
1367 static int kprobe_register(struct trace_event_call *event,
1368                            enum trace_reg type, void *data)
1369 {
1370         struct trace_kprobe *tk = (struct trace_kprobe *)event->data;
1371         struct trace_event_file *file = data;
1372
1373         switch (type) {
1374         case TRACE_REG_REGISTER:
1375                 return enable_trace_kprobe(tk, file);
1376         case TRACE_REG_UNREGISTER:
1377                 return disable_trace_kprobe(tk, file);
1378
1379 #ifdef CONFIG_PERF_EVENTS
1380         case TRACE_REG_PERF_REGISTER:
1381                 return enable_trace_kprobe(tk, NULL);
1382         case TRACE_REG_PERF_UNREGISTER:
1383                 return disable_trace_kprobe(tk, NULL);
1384         case TRACE_REG_PERF_OPEN:
1385         case TRACE_REG_PERF_CLOSE:
1386         case TRACE_REG_PERF_ADD:
1387         case TRACE_REG_PERF_DEL:
1388                 return 0;
1389 #endif
1390         }
1391         return 0;
1392 }
1393
1394 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1395 {
1396         struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
1397         int ret = 0;
1398
1399         raw_cpu_inc(*tk->nhit);
1400
1401         if (tk->tp.flags & TP_FLAG_TRACE)
1402                 kprobe_trace_func(tk, regs);
1403 #ifdef CONFIG_PERF_EVENTS
1404         if (tk->tp.flags & TP_FLAG_PROFILE)
1405                 ret = kprobe_perf_func(tk, regs);
1406 #endif
1407         return ret;
1408 }
1409 NOKPROBE_SYMBOL(kprobe_dispatcher);
1410
1411 static int
1412 kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1413 {
1414         struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
1415
1416         raw_cpu_inc(*tk->nhit);
1417
1418         if (tk->tp.flags & TP_FLAG_TRACE)
1419                 kretprobe_trace_func(tk, ri, regs);
1420 #ifdef CONFIG_PERF_EVENTS
1421         if (tk->tp.flags & TP_FLAG_PROFILE)
1422                 kretprobe_perf_func(tk, ri, regs);
1423 #endif
1424         return 0;       /* We don't tweek kernel, so just return 0 */
1425 }
1426 NOKPROBE_SYMBOL(kretprobe_dispatcher);
1427
1428 static struct trace_event_functions kretprobe_funcs = {
1429         .trace          = print_kretprobe_event
1430 };
1431
1432 static struct trace_event_functions kprobe_funcs = {
1433         .trace          = print_kprobe_event
1434 };
1435
1436 static inline void init_trace_event_call(struct trace_kprobe *tk,
1437                                          struct trace_event_call *call)
1438 {
1439         INIT_LIST_HEAD(&call->class->fields);
1440         if (trace_kprobe_is_return(tk)) {
1441                 call->event.funcs = &kretprobe_funcs;
1442                 call->class->define_fields = kretprobe_event_define_fields;
1443         } else {
1444                 call->event.funcs = &kprobe_funcs;
1445                 call->class->define_fields = kprobe_event_define_fields;
1446         }
1447
1448         call->flags = TRACE_EVENT_FL_KPROBE;
1449         call->class->reg = kprobe_register;
1450         call->data = tk;
1451 }
1452
1453 static int register_kprobe_event(struct trace_kprobe *tk)
1454 {
1455         struct trace_event_call *call = &tk->tp.call;
1456         int ret = 0;
1457
1458         init_trace_event_call(tk, call);
1459
1460         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
1461                 return -ENOMEM;
1462         ret = register_trace_event(&call->event);
1463         if (!ret) {
1464                 kfree(call->print_fmt);
1465                 return -ENODEV;
1466         }
1467         ret = trace_add_event_call(call);
1468         if (ret) {
1469                 pr_info("Failed to register kprobe event: %s\n",
1470                         trace_event_name(call));
1471                 kfree(call->print_fmt);
1472                 unregister_trace_event(&call->event);
1473         }
1474         return ret;
1475 }
1476
1477 static int unregister_kprobe_event(struct trace_kprobe *tk)
1478 {
1479         int ret;
1480
1481         /* tp->event is unregistered in trace_remove_event_call() */
1482         ret = trace_remove_event_call(&tk->tp.call);
1483         if (!ret)
1484                 kfree(tk->tp.call.print_fmt);
1485         return ret;
1486 }
1487
1488 #ifdef CONFIG_PERF_EVENTS
1489 /* create a trace_kprobe, but don't add it to global lists */
1490 struct trace_event_call *
1491 create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
1492                           bool is_return)
1493 {
1494         struct trace_kprobe *tk;
1495         int ret;
1496         char *event;
1497
1498         /*
1499          * local trace_kprobes are not added to probe_list, so they are never
1500          * searched in find_trace_kprobe(). Therefore, there is no concern of
1501          * duplicated name here.
1502          */
1503         event = func ? func : "DUMMY_EVENT";
1504
1505         tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
1506                                 offs, 0 /* maxactive */, 0 /* nargs */,
1507                                 is_return);
1508
1509         if (IS_ERR(tk)) {
1510                 pr_info("Failed to allocate trace_probe.(%d)\n",
1511                         (int)PTR_ERR(tk));
1512                 return ERR_CAST(tk);
1513         }
1514
1515         init_trace_event_call(tk, &tk->tp.call);
1516
1517         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
1518                 ret = -ENOMEM;
1519                 goto error;
1520         }
1521
1522         ret = __register_trace_kprobe(tk);
1523         if (ret < 0) {
1524                 kfree(tk->tp.call.print_fmt);
1525                 goto error;
1526         }
1527
1528         return &tk->tp.call;
1529 error:
1530         free_trace_kprobe(tk);
1531         return ERR_PTR(ret);
1532 }
1533
1534 void destroy_local_trace_kprobe(struct trace_event_call *event_call)
1535 {
1536         struct trace_kprobe *tk;
1537
1538         tk = container_of(event_call, struct trace_kprobe, tp.call);
1539
1540         if (trace_probe_is_enabled(&tk->tp)) {
1541                 WARN_ON(1);
1542                 return;
1543         }
1544
1545         __unregister_trace_kprobe(tk);
1546
1547         kfree(tk->tp.call.print_fmt);
1548         free_trace_kprobe(tk);
1549 }
1550 #endif /* CONFIG_PERF_EVENTS */
1551
1552 /* Make a tracefs interface for controlling probe points */
1553 static __init int init_kprobe_trace(void)
1554 {
1555         struct dentry *d_tracer;
1556         struct dentry *entry;
1557
1558         if (register_module_notifier(&trace_kprobe_module_nb))
1559                 return -EINVAL;
1560
1561         d_tracer = tracing_init_dentry();
1562         if (IS_ERR(d_tracer))
1563                 return 0;
1564
1565         entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
1566                                     NULL, &kprobe_events_ops);
1567
1568         /* Event list interface */
1569         if (!entry)
1570                 pr_warn("Could not create tracefs 'kprobe_events' entry\n");
1571
1572         /* Profile interface */
1573         entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
1574                                     NULL, &kprobe_profile_ops);
1575
1576         if (!entry)
1577                 pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
1578         return 0;
1579 }
1580 fs_initcall(init_kprobe_trace);
1581
1582
1583 #ifdef CONFIG_FTRACE_STARTUP_TEST
1584 static __init struct trace_event_file *
1585 find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
1586 {
1587         struct trace_event_file *file;
1588
1589         list_for_each_entry(file, &tr->events, list)
1590                 if (file->event_call == &tk->tp.call)
1591                         return file;
1592
1593         return NULL;
1594 }
1595
1596 /*
1597  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
1598  * stage, we can do this lockless.
1599  */
1600 static __init int kprobe_trace_self_tests_init(void)
1601 {
1602         int ret, warn = 0;
1603         int (*target)(int, int, int, int, int, int);
1604         struct trace_kprobe *tk;
1605         struct trace_event_file *file;
1606
1607         if (tracing_is_disabled())
1608                 return -ENODEV;
1609
1610         target = kprobe_trace_selftest_target;
1611
1612         pr_info("Testing kprobe tracing: ");
1613
1614         ret = trace_run_command("p:testprobe kprobe_trace_selftest_target "
1615                                 "$stack $stack0 +0($stack)",
1616                                 create_trace_kprobe);
1617         if (WARN_ON_ONCE(ret)) {
1618                 pr_warn("error on probing function entry.\n");
1619                 warn++;
1620         } else {
1621                 /* Enable trace point */
1622                 tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1623                 if (WARN_ON_ONCE(tk == NULL)) {
1624                         pr_warn("error on getting new probe.\n");
1625                         warn++;
1626                 } else {
1627                         file = find_trace_probe_file(tk, top_trace_array());
1628                         if (WARN_ON_ONCE(file == NULL)) {
1629                                 pr_warn("error on getting probe file.\n");
1630                                 warn++;
1631                         } else
1632                                 enable_trace_kprobe(tk, file);
1633                 }
1634         }
1635
1636         ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target "
1637                                 "$retval", create_trace_kprobe);
1638         if (WARN_ON_ONCE(ret)) {
1639                 pr_warn("error on probing function return.\n");
1640                 warn++;
1641         } else {
1642                 /* Enable trace point */
1643                 tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1644                 if (WARN_ON_ONCE(tk == NULL)) {
1645                         pr_warn("error on getting 2nd new probe.\n");
1646                         warn++;
1647                 } else {
1648                         file = find_trace_probe_file(tk, top_trace_array());
1649                         if (WARN_ON_ONCE(file == NULL)) {
1650                                 pr_warn("error on getting probe file.\n");
1651                                 warn++;
1652                         } else
1653                                 enable_trace_kprobe(tk, file);
1654                 }
1655         }
1656
1657         if (warn)
1658                 goto end;
1659
1660         ret = target(1, 2, 3, 4, 5, 6);
1661
1662         /*
1663          * Not expecting an error here, the check is only to prevent the
1664          * optimizer from removing the call to target() as otherwise there
1665          * are no side-effects and the call is never performed.
1666          */
1667         if (ret != 21)
1668                 warn++;
1669
1670         /* Disable trace points before removing it */
1671         tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1672         if (WARN_ON_ONCE(tk == NULL)) {
1673                 pr_warn("error on getting test probe.\n");
1674                 warn++;
1675         } else {
1676                 if (trace_kprobe_nhit(tk) != 1) {
1677                         pr_warn("incorrect number of testprobe hits\n");
1678                         warn++;
1679                 }
1680
1681                 file = find_trace_probe_file(tk, top_trace_array());
1682                 if (WARN_ON_ONCE(file == NULL)) {
1683                         pr_warn("error on getting probe file.\n");
1684                         warn++;
1685                 } else
1686                         disable_trace_kprobe(tk, file);
1687         }
1688
1689         tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1690         if (WARN_ON_ONCE(tk == NULL)) {
1691                 pr_warn("error on getting 2nd test probe.\n");
1692                 warn++;
1693         } else {
1694                 if (trace_kprobe_nhit(tk) != 1) {
1695                         pr_warn("incorrect number of testprobe2 hits\n");
1696                         warn++;
1697                 }
1698
1699                 file = find_trace_probe_file(tk, top_trace_array());
1700                 if (WARN_ON_ONCE(file == NULL)) {
1701                         pr_warn("error on getting probe file.\n");
1702                         warn++;
1703                 } else
1704                         disable_trace_kprobe(tk, file);
1705         }
1706
1707         ret = trace_run_command("-:testprobe", create_trace_kprobe);
1708         if (WARN_ON_ONCE(ret)) {
1709                 pr_warn("error on deleting a probe.\n");
1710                 warn++;
1711         }
1712
1713         ret = trace_run_command("-:testprobe2", create_trace_kprobe);
1714         if (WARN_ON_ONCE(ret)) {
1715                 pr_warn("error on deleting a probe.\n");
1716                 warn++;
1717         }
1718
1719 end:
1720         release_all_trace_kprobes();
1721         /*
1722          * Wait for the optimizer work to finish. Otherwise it might fiddle
1723          * with probes in already freed __init text.
1724          */
1725         wait_for_kprobe_optimizer();
1726         if (warn)
1727                 pr_cont("NG: Some tests are failed. Please check them.\n");
1728         else
1729                 pr_cont("OK\n");
1730         return 0;
1731 }
1732
1733 late_initcall(kprobe_trace_self_tests_init);
1734
1735 #endif