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