kernel/trace/trace_kprobe.c

   1 /*
   2  * Kprobes-based tracing events
   3  *
   4  * Created by Masami Hiramatsu <mhiramat@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/uaccess.h>
  22
  23 #include "trace_probe.h"
  24
  25 #define KPROBE_EVENT_SYSTEM "kprobes"
  26
  27 /**
  28  * Kprobe event core functions
  29  */
  30 struct trace_kprobe {
  31         struct list_head        list;
  32         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
  33         unsigned long __percpu *nhit;
  34         const char              *symbol;        /* symbol name */
  35         struct trace_probe      tp;
  36 };
  37
  38 #define SIZEOF_TRACE_KPROBE(n)                          \
  39         (offsetof(struct trace_kprobe, tp.args) +       \
  40         (sizeof(struct probe_arg) * (n)))
  41
  42
  43 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
  44 {
  45         return tk->rp.handler != NULL;
  46 }
  47
  48 static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
  49 {
  50         return tk->symbol ? tk->symbol : "unknown";
  51 }
  52
  53 static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
  54 {
  55         return tk->rp.kp.offset;
  56 }
  57
  58 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
  59 {
  60         return !!(kprobe_gone(&tk->rp.kp));
  61 }
  62
  63 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
  64                                                  struct module *mod)
  65 {
  66         int len = strlen(mod->name);
  67         const char *name = trace_kprobe_symbol(tk);
  68         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
  69 }
  70
  71 static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)
  72 {
  73         return !!strchr(trace_kprobe_symbol(tk), ':');
  74 }
  75
  76 static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
  77 {
  78         unsigned long nhit = 0;
  79         int cpu;
  80
  81         for_each_possible_cpu(cpu)
  82                 nhit += *per_cpu_ptr(tk->nhit, cpu);
  83
  84         return nhit;
  85 }
  86
  87 static int register_kprobe_event(struct trace_kprobe *tk);
  88 static int unregister_kprobe_event(struct trace_kprobe *tk);
  89
  90 static DEFINE_MUTEX(probe_lock);
  91 static LIST_HEAD(probe_list);
  92
  93 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
  94 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
  95                                 struct pt_regs *regs);
  96
  97 /* Memory fetching by symbol */
  98 struct symbol_cache {
  99         char            *symbol;
 100         long            offset;
 101         unsigned long   addr;
 102 };
 103
 104 unsigned long update_symbol_cache(struct symbol_cache *sc)
 105 {
 106         sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
 107
 108         if (sc->addr)
 109                 sc->addr += sc->offset;
 110
 111         return sc->addr;
 112 }
 113
 114 void free_symbol_cache(struct symbol_cache *sc)
 115 {
 116         kfree(sc->symbol);
 117         kfree(sc);
 118 }
 119
 120 struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
 121 {
 122         struct symbol_cache *sc;
 123
 124         if (!sym || strlen(sym) == 0)
 125                 return NULL;
 126
 127         sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
 128         if (!sc)
 129                 return NULL;
 130
 131         sc->symbol = kstrdup(sym, GFP_KERNEL);
 132         if (!sc->symbol) {
 133                 kfree(sc);
 134                 return NULL;
 135         }
 136         sc->offset = offset;
 137         update_symbol_cache(sc);
 138
 139         return sc;
 140 }
 141
 142 /*
 143  * Kprobes-specific fetch functions
 144  */
 145 #define DEFINE_FETCH_stack(type)                                        \
 146 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
 147                                           void *offset, void *dest)     \
 148 {                                                                       \
 149         *(type *)dest = (type)regs_get_kernel_stack_nth(regs,           \
 150                                 (unsigned int)((unsigned long)offset)); \
 151 }                                                                       \
 152 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
 153
 154 DEFINE_BASIC_FETCH_FUNCS(stack)
 155 /* No string on the stack entry */
 156 #define fetch_stack_string      NULL
 157 #define fetch_stack_string_size NULL
 158
 159 #define DEFINE_FETCH_memory(type)                                       \
 160 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
 161                                           void *addr, void *dest)       \
 162 {                                                                       \
 163         type retval;                                                    \
 164         if (probe_kernel_address(addr, retval))                         \
 165                 *(type *)dest = 0;                                      \
 166         else                                                            \
 167                 *(type *)dest = retval;                                 \
 168 }                                                                       \
 169 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
 170
 171 DEFINE_BASIC_FETCH_FUNCS(memory)
 172 /*
 173  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 174  * length and relative data location.
 175  */
 176 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
 177                                             void *addr, void *dest)
 178 {
 179         int maxlen = get_rloc_len(*(u32 *)dest);
 180         u8 *dst = get_rloc_data(dest);
 181         long ret;
 182
 183         if (!maxlen)
 184                 return;
 185
 186         /*
 187          * Try to get string again, since the string can be changed while
 188          * probing.
 189          */
 190         ret = strncpy_from_unsafe(dst, addr, maxlen);
 191
 192         if (ret < 0) {  /* Failed to fetch string */
 193                 dst[0] = '\0';
 194                 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
 195         } else {
 196                 *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
 197         }
 198 }
 199 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
 200
 201 /* Return the length of string -- including null terminal byte */
 202 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 203                                                  void *addr, void *dest)
 204 {
 205         mm_segment_t old_fs;
 206         int ret, len = 0;
 207         u8 c;
 208
 209         old_fs = get_fs();
 210         set_fs(KERNEL_DS);
 211         pagefault_disable();
 212
 213         do {
 214                 ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
 215                 len++;
 216         } while (c && ret == 0 && len < MAX_STRING_SIZE);
 217
 218         pagefault_enable();
 219         set_fs(old_fs);
 220
 221         if (ret < 0)    /* Failed to check the length */
 222                 *(u32 *)dest = 0;
 223         else
 224                 *(u32 *)dest = len;
 225 }
 226 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
 227
 228 #define DEFINE_FETCH_symbol(type)                                       \
 229 void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
 230 {                                                                       \
 231         struct symbol_cache *sc = data;                                 \
 232         if (sc->addr)                                                   \
 233                 fetch_memory_##type(regs, (void *)sc->addr, dest);      \
 234         else                                                            \
 235                 *(type *)dest = 0;                                      \
 236 }                                                                       \
 237 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
 238
 239 DEFINE_BASIC_FETCH_FUNCS(symbol)
 240 DEFINE_FETCH_symbol(string)
 241 DEFINE_FETCH_symbol(string_size)
 242
 243 /* kprobes don't support file_offset fetch methods */
 244 #define fetch_file_offset_u8            NULL
 245 #define fetch_file_offset_u16           NULL
 246 #define fetch_file_offset_u32           NULL
 247 #define fetch_file_offset_u64           NULL
 248 #define fetch_file_offset_string        NULL
 249 #define fetch_file_offset_string_size   NULL
 250
 251 /* Fetch type information table */
 252 static const struct fetch_type kprobes_fetch_type_table[] = {
 253         /* Special types */
 254         [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
 255                                         sizeof(u32), 1, "__data_loc char[]"),
 256         [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
 257                                         string_size, sizeof(u32), 0, "u32"),
 258         /* Basic types */
 259         ASSIGN_FETCH_TYPE(u8,  u8,  0),
 260         ASSIGN_FETCH_TYPE(u16, u16, 0),
 261         ASSIGN_FETCH_TYPE(u32, u32, 0),
 262         ASSIGN_FETCH_TYPE(u64, u64, 0),
 263         ASSIGN_FETCH_TYPE(s8,  u8,  1),
 264         ASSIGN_FETCH_TYPE(s16, u16, 1),
 265         ASSIGN_FETCH_TYPE(s32, u32, 1),
 266         ASSIGN_FETCH_TYPE(s64, u64, 1),
 267         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
 268         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 269         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 270         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
 271
 272         ASSIGN_FETCH_TYPE_END
 273 };
 274
 275 /*
 276  * Allocate new trace_probe and initialize it (including kprobes).
 277  */
 278 static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 279                                              const char *event,
 280                                              void *addr,
 281                                              const char *symbol,
 282                                              unsigned long offs,
 283                                              int nargs, bool is_return)
 284 {
 285         struct trace_kprobe *tk;
 286         int ret = -ENOMEM;
 287
 288         tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
 289         if (!tk)
 290                 return ERR_PTR(ret);
 291
 292         tk->nhit = alloc_percpu(unsigned long);
 293         if (!tk->nhit)
 294                 goto error;
 295
 296         if (symbol) {
 297                 tk->symbol = kstrdup(symbol, GFP_KERNEL);
 298                 if (!tk->symbol)
 299                         goto error;
 300                 tk->rp.kp.symbol_name = tk->symbol;
 301                 tk->rp.kp.offset = offs;
 302         } else
 303                 tk->rp.kp.addr = addr;
 304
 305         if (is_return)
 306                 tk->rp.handler = kretprobe_dispatcher;
 307         else
 308                 tk->rp.kp.pre_handler = kprobe_dispatcher;
 309
 310         if (!event || !is_good_name(event)) {
 311                 ret = -EINVAL;
 312                 goto error;
 313         }
 314
 315         tk->tp.call.class = &tk->tp.class;
 316         tk->tp.call.name = kstrdup(event, GFP_KERNEL);
 317         if (!tk->tp.call.name)
 318                 goto error;
 319
 320         if (!group || !is_good_name(group)) {
 321                 ret = -EINVAL;
 322                 goto error;
 323         }
 324
 325         tk->tp.class.system = kstrdup(group, GFP_KERNEL);
 326         if (!tk->tp.class.system)
 327                 goto error;
 328
 329         INIT_LIST_HEAD(&tk->list);
 330         INIT_LIST_HEAD(&tk->tp.files);
 331         return tk;
 332 error:
 333         kfree(tk->tp.call.name);
 334         kfree(tk->symbol);
 335         free_percpu(tk->nhit);
 336         kfree(tk);
 337         return ERR_PTR(ret);
 338 }
 339
 340 static void free_trace_kprobe(struct trace_kprobe *tk)
 341 {
 342         int i;
 343
 344         for (i = 0; i < tk->tp.nr_args; i++)
 345                 traceprobe_free_probe_arg(&tk->tp.args[i]);
 346
 347         kfree(tk->tp.call.class->system);
 348         kfree(tk->tp.call.name);
 349         kfree(tk->symbol);
 350         free_percpu(tk->nhit);
 351         kfree(tk);
 352 }
 353
 354 static struct trace_kprobe *find_trace_kprobe(const char *event,
 355                                               const char *group)
 356 {
 357         struct trace_kprobe *tk;
 358
 359         list_for_each_entry(tk, &probe_list, list)
 360                 if (strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
 361                     strcmp(tk->tp.call.class->system, group) == 0)
 362                         return tk;
 363         return NULL;
 364 }
 365
 366 /*
 367  * Enable trace_probe
 368  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
 369  */
 370 static int
 371 enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 372 {
 373         int ret = 0;
 374
 375         if (file) {
 376                 struct event_file_link *link;
 377
 378                 link = kmalloc(sizeof(*link), GFP_KERNEL);
 379                 if (!link) {
 380                         ret = -ENOMEM;
 381                         goto out;
 382                 }
 383
 384                 link->file = file;
 385                 list_add_tail_rcu(&link->list, &tk->tp.files);
 386
 387                 tk->tp.flags |= TP_FLAG_TRACE;
 388         } else
 389                 tk->tp.flags |= TP_FLAG_PROFILE;
 390
 391         if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
 392                 if (trace_kprobe_is_return(tk))
 393                         ret = enable_kretprobe(&tk->rp);
 394                 else
 395                         ret = enable_kprobe(&tk->rp.kp);
 396         }
 397  out:
 398         return ret;
 399 }
 400
 401 /*
 402  * Disable trace_probe
 403  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
 404  */
 405 static int
 406 disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 407 {
 408         struct event_file_link *link = NULL;
 409         int wait = 0;
 410         int ret = 0;
 411
 412         if (file) {
 413                 link = find_event_file_link(&tk->tp, file);
 414                 if (!link) {
 415                         ret = -EINVAL;
 416                         goto out;
 417                 }
 418
 419                 list_del_rcu(&link->list);
 420                 wait = 1;
 421                 if (!list_empty(&tk->tp.files))
 422                         goto out;
 423
 424                 tk->tp.flags &= ~TP_FLAG_TRACE;
 425         } else
 426                 tk->tp.flags &= ~TP_FLAG_PROFILE;
 427
 428         if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
 429                 if (trace_kprobe_is_return(tk))
 430                         disable_kretprobe(&tk->rp);
 431                 else
 432                         disable_kprobe(&tk->rp.kp);
 433                 wait = 1;
 434         }
 435  out:
 436         if (wait) {
 437                 /*
 438                  * Synchronize with kprobe_trace_func/kretprobe_trace_func
 439                  * to ensure disabled (all running handlers are finished).
 440                  * This is not only for kfree(), but also the caller,
 441                  * trace_remove_event_call() supposes it for releasing
 442                  * event_call related objects, which will be accessed in
 443                  * the kprobe_trace_func/kretprobe_trace_func.
 444                  */
 445                 synchronize_sched();
 446                 kfree(link);    /* Ignored if link == NULL */
 447         }
 448
 449         return ret;
 450 }
 451
 452 /* Internal register function - just handle k*probes and flags */
 453 static int __register_trace_kprobe(struct trace_kprobe *tk)
 454 {
 455         int i, ret;
 456
 457         if (trace_probe_is_registered(&tk->tp))
 458                 return -EINVAL;
 459
 460         for (i = 0; i < tk->tp.nr_args; i++)
 461                 traceprobe_update_arg(&tk->tp.args[i]);
 462
 463         /* Set/clear disabled flag according to tp->flag */
 464         if (trace_probe_is_enabled(&tk->tp))
 465                 tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
 466         else
 467                 tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
 468
 469         if (trace_kprobe_is_return(tk))
 470                 ret = register_kretprobe(&tk->rp);
 471         else
 472                 ret = register_kprobe(&tk->rp.kp);
 473
 474         if (ret == 0)
 475                 tk->tp.flags |= TP_FLAG_REGISTERED;
 476         else {
 477                 pr_warn("Could not insert probe at %s+%lu: %d\n",
 478                         trace_kprobe_symbol(tk), trace_kprobe_offset(tk), ret);
 479                 if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
 480                         pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
 481                         ret = 0;
 482                 } else if (ret == -EILSEQ) {
 483                         pr_warn("Probing address(0x%p) is not an instruction boundary.\n",
 484                                 tk->rp.kp.addr);
 485                         ret = -EINVAL;
 486                 }
 487         }
 488
 489         return ret;
 490 }
 491
 492 /* Internal unregister function - just handle k*probes and flags */
 493 static void __unregister_trace_kprobe(struct trace_kprobe *tk)
 494 {
 495         if (trace_probe_is_registered(&tk->tp)) {
 496                 if (trace_kprobe_is_return(tk))
 497                         unregister_kretprobe(&tk->rp);
 498                 else
 499                         unregister_kprobe(&tk->rp.kp);
 500                 tk->tp.flags &= ~TP_FLAG_REGISTERED;
 501                 /* Cleanup kprobe for reuse */
 502                 if (tk->rp.kp.symbol_name)
 503                         tk->rp.kp.addr = NULL;
 504         }
 505 }
 506
 507 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
 508 static int unregister_trace_kprobe(struct trace_kprobe *tk)
 509 {
 510         /* Enabled event can not be unregistered */
 511         if (trace_probe_is_enabled(&tk->tp))
 512                 return -EBUSY;
 513
 514         /* Will fail if probe is being used by ftrace or perf */
 515         if (unregister_kprobe_event(tk))
 516                 return -EBUSY;
 517
 518         __unregister_trace_kprobe(tk);
 519         list_del(&tk->list);
 520
 521         return 0;
 522 }
 523
 524 /* Register a trace_probe and probe_event */
 525 static int register_trace_kprobe(struct trace_kprobe *tk)
 526 {
 527         struct trace_kprobe *old_tk;
 528         int ret;
 529
 530         mutex_lock(&probe_lock);
 531
 532         /* Delete old (same name) event if exist */
 533         old_tk = find_trace_kprobe(trace_event_name(&tk->tp.call),
 534                         tk->tp.call.class->system);
 535         if (old_tk) {
 536                 ret = unregister_trace_kprobe(old_tk);
 537                 if (ret < 0)
 538                         goto end;
 539                 free_trace_kprobe(old_tk);
 540         }
 541
 542         /* Register new event */
 543         ret = register_kprobe_event(tk);
 544         if (ret) {
 545                 pr_warn("Failed to register probe event(%d)\n", ret);
 546                 goto end;
 547         }
 548
 549         /* Register k*probe */
 550         ret = __register_trace_kprobe(tk);
 551         if (ret < 0)
 552                 unregister_kprobe_event(tk);
 553         else
 554                 list_add_tail(&tk->list, &probe_list);
 555
 556 end:
 557         mutex_unlock(&probe_lock);
 558         return ret;
 559 }
 560
 561 /* Module notifier call back, checking event on the module */
 562 static int trace_kprobe_module_callback(struct notifier_block *nb,
 563                                        unsigned long val, void *data)
 564 {
 565         struct module *mod = data;
 566         struct trace_kprobe *tk;
 567         int ret;
 568
 569         if (val != MODULE_STATE_COMING)
 570                 return NOTIFY_DONE;
 571
 572         /* Update probes on coming module */
 573         mutex_lock(&probe_lock);
 574         list_for_each_entry(tk, &probe_list, list) {
 575                 if (trace_kprobe_within_module(tk, mod)) {
 576                         /* Don't need to check busy - this should have gone. */
 577                         __unregister_trace_kprobe(tk);
 578                         ret = __register_trace_kprobe(tk);
 579                         if (ret)
 580                                 pr_warn("Failed to re-register probe %s on %s: %d\n",
 581                                         trace_event_name(&tk->tp.call),
 582                                         mod->name, ret);
 583                 }
 584         }
 585         mutex_unlock(&probe_lock);
 586
 587         return NOTIFY_DONE;
 588 }
 589
 590 static struct notifier_block trace_kprobe_module_nb = {
 591         .notifier_call = trace_kprobe_module_callback,
 592         .priority = 1   /* Invoked after kprobe module callback */
 593 };
 594
 595 static int create_trace_kprobe(int argc, char **argv)
 596 {
 597         /*
 598          * Argument syntax:
 599          *  - Add kprobe: p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
 600          *  - Add kretprobe: r[:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
 601          * Fetch args:
 602          *  $retval     : fetch return value
 603          *  $stack      : fetch stack address
 604          *  $stackN     : fetch Nth of stack (N:0-)
 605          *  $comm       : fetch current task comm
 606          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
 607          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 608          *  %REG        : fetch register REG
 609          * Dereferencing memory fetch:
 610          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
 611          * Alias name of args:
 612          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
 613          * Type of args:
 614          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 615          */
 616         struct trace_kprobe *tk;
 617         int i, ret = 0;
 618         bool is_return = false, is_delete = false;
 619         char *symbol = NULL, *event = NULL, *group = NULL;
 620         char *arg;
 621         unsigned long offset = 0;
 622         void *addr = NULL;
 623         char buf[MAX_EVENT_NAME_LEN];
 624
 625         /* argc must be >= 1 */
 626         if (argv[0][0] == 'p')
 627                 is_return = false;
 628         else if (argv[0][0] == 'r')
 629                 is_return = true;
 630         else if (argv[0][0] == '-')
 631                 is_delete = true;
 632         else {
 633                 pr_info("Probe definition must be started with 'p', 'r' or"
 634                         " '-'.\n");
 635                 return -EINVAL;
 636         }
 637
 638         if (argv[0][1] == ':') {
 639                 event = &argv[0][2];
 640                 if (strchr(event, '/')) {
 641                         group = event;
 642                         event = strchr(group, '/') + 1;
 643                         event[-1] = '\0';
 644                         if (strlen(group) == 0) {
 645                                 pr_info("Group name is not specified\n");
 646                                 return -EINVAL;
 647                         }
 648                 }
 649                 if (strlen(event) == 0) {
 650                         pr_info("Event name is not specified\n");
 651                         return -EINVAL;
 652                 }
 653         }
 654         if (!group)
 655                 group = KPROBE_EVENT_SYSTEM;
 656
 657         if (is_delete) {
 658                 if (!event) {
 659                         pr_info("Delete command needs an event name.\n");
 660                         return -EINVAL;
 661                 }
 662                 mutex_lock(&probe_lock);
 663                 tk = find_trace_kprobe(event, group);
 664                 if (!tk) {
 665                         mutex_unlock(&probe_lock);
 666                         pr_info("Event %s/%s doesn't exist.\n", group, event);
 667                         return -ENOENT;
 668                 }
 669                 /* delete an event */
 670                 ret = unregister_trace_kprobe(tk);
 671                 if (ret == 0)
 672                         free_trace_kprobe(tk);
 673                 mutex_unlock(&probe_lock);
 674                 return ret;
 675         }
 676
 677         if (argc < 2) {
 678                 pr_info("Probe point is not specified.\n");
 679                 return -EINVAL;
 680         }
 681         if (isdigit(argv[1][0])) {
 682                 if (is_return) {
 683                         pr_info("Return probe point must be a symbol.\n");
 684                         return -EINVAL;
 685                 }
 686                 /* an address specified */
 687                 ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
 688                 if (ret) {
 689                         pr_info("Failed to parse address.\n");
 690                         return ret;
 691                 }
 692         } else {
 693                 /* a symbol specified */
 694                 symbol = argv[1];
 695                 /* TODO: support .init module functions */
 696                 ret = traceprobe_split_symbol_offset(symbol, &offset);
 697                 if (ret) {
 698                         pr_info("Failed to parse symbol.\n");
 699                         return ret;
 700                 }
 701                 if (offset && is_return) {
 702                         pr_info("Return probe must be used without offset.\n");
 703                         return -EINVAL;
 704                 }
 705         }
 706         argc -= 2; argv += 2;
 707
 708         /* setup a probe */
 709         if (!event) {
 710                 /* Make a new event name */
 711                 if (symbol)
 712                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
 713                                  is_return ? 'r' : 'p', symbol, offset);
 714                 else
 715                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
 716                                  is_return ? 'r' : 'p', addr);
 717                 event = buf;
 718         }
 719         tk = alloc_trace_kprobe(group, event, addr, symbol, offset, argc,
 720                                is_return);
 721         if (IS_ERR(tk)) {
 722                 pr_info("Failed to allocate trace_probe.(%d)\n",
 723                         (int)PTR_ERR(tk));
 724                 return PTR_ERR(tk);
 725         }
 726
 727         /* parse arguments */
 728         ret = 0;
 729         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
 730                 struct probe_arg *parg = &tk->tp.args[i];
 731
 732                 /* Increment count for freeing args in error case */
 733                 tk->tp.nr_args++;
 734
 735                 /* Parse argument name */
 736                 arg = strchr(argv[i], '=');
 737                 if (arg) {
 738                         *arg++ = '\0';
 739                         parg->name = kstrdup(argv[i], GFP_KERNEL);
 740                 } else {
 741                         arg = argv[i];
 742                         /* If argument name is omitted, set "argN" */
 743                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
 744                         parg->name = kstrdup(buf, GFP_KERNEL);
 745                 }
 746
 747                 if (!parg->name) {
 748                         pr_info("Failed to allocate argument[%d] name.\n", i);
 749                         ret = -ENOMEM;
 750                         goto error;
 751                 }
 752
 753                 if (!is_good_name(parg->name)) {
 754                         pr_info("Invalid argument[%d] name: %s\n",
 755                                 i, parg->name);
 756                         ret = -EINVAL;
 757                         goto error;
 758                 }
 759
 760                 if (traceprobe_conflict_field_name(parg->name,
 761                                                         tk->tp.args, i)) {
 762                         pr_info("Argument[%d] name '%s' conflicts with "
 763                                 "another field.\n", i, argv[i]);
 764                         ret = -EINVAL;
 765                         goto error;
 766                 }
 767
 768                 /* Parse fetch argument */
 769                 ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
 770                                                 is_return, true,
 771                                                 kprobes_fetch_type_table);
 772                 if (ret) {
 773                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 774                         goto error;
 775                 }
 776         }
 777
 778         ret = register_trace_kprobe(tk);
 779         if (ret)
 780                 goto error;
 781         return 0;
 782
 783 error:
 784         free_trace_kprobe(tk);
 785         return ret;
 786 }
 787
 788 static int release_all_trace_kprobes(void)
 789 {
 790         struct trace_kprobe *tk;
 791         int ret = 0;
 792
 793         mutex_lock(&probe_lock);
 794         /* Ensure no probe is in use. */
 795         list_for_each_entry(tk, &probe_list, list)
 796                 if (trace_probe_is_enabled(&tk->tp)) {
 797                         ret = -EBUSY;
 798                         goto end;
 799                 }
 800         /* TODO: Use batch unregistration */
 801         while (!list_empty(&probe_list)) {
 802                 tk = list_entry(probe_list.next, struct trace_kprobe, list);
 803                 ret = unregister_trace_kprobe(tk);
 804                 if (ret)
 805                         goto end;
 806                 free_trace_kprobe(tk);
 807         }
 808
 809 end:
 810         mutex_unlock(&probe_lock);
 811
 812         return ret;
 813 }
 814
 815 /* Probes listing interfaces */
 816 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
 817 {
 818         mutex_lock(&probe_lock);
 819         return seq_list_start(&probe_list, *pos);
 820 }
 821
 822 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
 823 {
 824         return seq_list_next(v, &probe_list, pos);
 825 }
 826
 827 static void probes_seq_stop(struct seq_file *m, void *v)
 828 {
 829         mutex_unlock(&probe_lock);
 830 }
 831
 832 static int probes_seq_show(struct seq_file *m, void *v)
 833 {
 834         struct trace_kprobe *tk = v;
 835         int i;
 836
 837         seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
 838         seq_printf(m, ":%s/%s", tk->tp.call.class->system,
 839                         trace_event_name(&tk->tp.call));
 840
 841         if (!tk->symbol)
 842                 seq_printf(m, " 0x%p", tk->rp.kp.addr);
 843         else if (tk->rp.kp.offset)
 844                 seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
 845                            tk->rp.kp.offset);
 846         else
 847                 seq_printf(m, " %s", trace_kprobe_symbol(tk));
 848
 849         for (i = 0; i < tk->tp.nr_args; i++)
 850                 seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
 851         seq_putc(m, '\n');
 852
 853         return 0;
 854 }
 855
 856 static const struct seq_operations probes_seq_op = {
 857         .start  = probes_seq_start,
 858         .next   = probes_seq_next,
 859         .stop   = probes_seq_stop,
 860         .show   = probes_seq_show
 861 };
 862
 863 static int probes_open(struct inode *inode, struct file *file)
 864 {
 865         int ret;
 866
 867         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 868                 ret = release_all_trace_kprobes();
 869                 if (ret < 0)
 870                         return ret;
 871         }
 872
 873         return seq_open(file, &probes_seq_op);
 874 }
 875
 876 static ssize_t probes_write(struct file *file, const char __user *buffer,
 877                             size_t count, loff_t *ppos)
 878 {
 879         return traceprobe_probes_write(file, buffer, count, ppos,
 880                         create_trace_kprobe);
 881 }
 882
 883 static const struct file_operations kprobe_events_ops = {
 884         .owner          = THIS_MODULE,
 885         .open           = probes_open,
 886         .read           = seq_read,
 887         .llseek         = seq_lseek,
 888         .release        = seq_release,
 889         .write          = probes_write,
 890 };
 891
 892 /* Probes profiling interfaces */
 893 static int probes_profile_seq_show(struct seq_file *m, void *v)
 894 {
 895         struct trace_kprobe *tk = v;
 896
 897         seq_printf(m, "  %-44s %15lu %15lu\n",
 898                    trace_event_name(&tk->tp.call),
 899                    trace_kprobe_nhit(tk),
 900                    tk->rp.kp.nmissed);
 901
 902         return 0;
 903 }
 904
 905 static const struct seq_operations profile_seq_op = {
 906         .start  = probes_seq_start,
 907         .next   = probes_seq_next,
 908         .stop   = probes_seq_stop,
 909         .show   = probes_profile_seq_show
 910 };
 911
 912 static int profile_open(struct inode *inode, struct file *file)
 913 {
 914         return seq_open(file, &profile_seq_op);
 915 }
 916
 917 static const struct file_operations kprobe_profile_ops = {
 918         .owner          = THIS_MODULE,
 919         .open           = profile_open,
 920         .read           = seq_read,
 921         .llseek         = seq_lseek,
 922         .release        = seq_release,
 923 };
 924
 925 /* Kprobe handler */
 926 static nokprobe_inline void
 927 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
 928                     struct trace_event_file *trace_file)
 929 {
 930         struct kprobe_trace_entry_head *entry;
 931         struct ring_buffer_event *event;
 932         struct ring_buffer *buffer;
 933         int size, dsize, pc;
 934         unsigned long irq_flags;
 935         struct trace_event_call *call = &tk->tp.call;
 936
 937         WARN_ON(call != trace_file->event_call);
 938
 939         if (trace_trigger_soft_disabled(trace_file))
 940                 return;
 941
 942         local_save_flags(irq_flags);
 943         pc = preempt_count();
 944
 945         dsize = __get_data_size(&tk->tp, regs);
 946         size = sizeof(*entry) + tk->tp.size + dsize;
 947
 948         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
 949                                                 call->event.type,
 950                                                 size, irq_flags, pc);
 951         if (!event)
 952                 return;
 953
 954         entry = ring_buffer_event_data(event);
 955         entry->ip = (unsigned long)tk->rp.kp.addr;
 956         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
 957
 958         event_trigger_unlock_commit_regs(trace_file, buffer, event,
 959                                          entry, irq_flags, pc, regs);
 960 }
 961
 962 static void
 963 kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
 964 {
 965         struct event_file_link *link;
 966
 967         list_for_each_entry_rcu(link, &tk->tp.files, list)
 968                 __kprobe_trace_func(tk, regs, link->file);
 969 }
 970 NOKPROBE_SYMBOL(kprobe_trace_func);
 971
 972 /* Kretprobe handler */
 973 static nokprobe_inline void
 974 __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
 975                        struct pt_regs *regs,
 976                        struct trace_event_file *trace_file)
 977 {
 978         struct kretprobe_trace_entry_head *entry;
 979         struct ring_buffer_event *event;
 980         struct ring_buffer *buffer;
 981         int size, pc, dsize;
 982         unsigned long irq_flags;
 983         struct trace_event_call *call = &tk->tp.call;
 984
 985         WARN_ON(call != trace_file->event_call);
 986
 987         if (trace_trigger_soft_disabled(trace_file))
 988                 return;
 989
 990         local_save_flags(irq_flags);
 991         pc = preempt_count();
 992
 993         dsize = __get_data_size(&tk->tp, regs);
 994         size = sizeof(*entry) + tk->tp.size + dsize;
 995
 996         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
 997                                                 call->event.type,
 998                                                 size, irq_flags, pc);
 999         if (!event)
1000                 return;
1001
1002         entry = ring_buffer_event_data(event);
1003         entry->func = (unsigned long)tk->rp.kp.addr;
1004         entry->ret_ip = (unsigned long)ri->ret_addr;
1005         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1006
1007         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1008                                          entry, irq_flags, pc, regs);
1009 }
1010
1011 static void
1012 kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1013                      struct pt_regs *regs)
1014 {
1015         struct event_file_link *link;
1016
1017         list_for_each_entry_rcu(link, &tk->tp.files, list)
1018                 __kretprobe_trace_func(tk, ri, regs, link->file);
1019 }
1020 NOKPROBE_SYMBOL(kretprobe_trace_func);
1021
1022 /* Event entry printers */
1023 static enum print_line_t
1024 print_kprobe_event(struct trace_iterator *iter, int flags,
1025                    struct trace_event *event)
1026 {
1027         struct kprobe_trace_entry_head *field;
1028         struct trace_seq *s = &iter->seq;
1029         struct trace_probe *tp;
1030         u8 *data;
1031         int i;
1032
1033         field = (struct kprobe_trace_entry_head *)iter->ent;
1034         tp = container_of(event, struct trace_probe, call.event);
1035
1036         trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
1037
1038         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
1039                 goto out;
1040
1041         trace_seq_putc(s, ')');
1042
1043         data = (u8 *)&field[1];
1044         for (i = 0; i < tp->nr_args; i++)
1045                 if (!tp->args[i].type->print(s, tp->args[i].name,
1046                                              data + tp->args[i].offset, field))
1047                         goto out;
1048
1049         trace_seq_putc(s, '\n');
1050  out:
1051         return trace_handle_return(s);
1052 }
1053
1054 static enum print_line_t
1055 print_kretprobe_event(struct trace_iterator *iter, int flags,
1056                       struct trace_event *event)
1057 {
1058         struct kretprobe_trace_entry_head *field;
1059         struct trace_seq *s = &iter->seq;
1060         struct trace_probe *tp;
1061         u8 *data;
1062         int i;
1063
1064         field = (struct kretprobe_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->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
1070                 goto out;
1071
1072         trace_seq_puts(s, " <- ");
1073
1074         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
1075                 goto out;
1076
1077         trace_seq_putc(s, ')');
1078
1079         data = (u8 *)&field[1];
1080         for (i = 0; i < tp->nr_args; i++)
1081                 if (!tp->args[i].type->print(s, tp->args[i].name,
1082                                              data + tp->args[i].offset, field))
1083                         goto out;
1084
1085         trace_seq_putc(s, '\n');
1086
1087  out:
1088         return trace_handle_return(s);
1089 }
1090
1091
1092 static int kprobe_event_define_fields(struct trace_event_call *event_call)
1093 {
1094         int ret, i;
1095         struct kprobe_trace_entry_head field;
1096         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1097
1098         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
1099         /* Set argument names as fields */
1100         for (i = 0; i < tk->tp.nr_args; i++) {
1101                 struct probe_arg *parg = &tk->tp.args[i];
1102
1103                 ret = trace_define_field(event_call, parg->type->fmttype,
1104                                          parg->name,
1105                                          sizeof(field) + parg->offset,
1106                                          parg->type->size,
1107                                          parg->type->is_signed,
1108                                          FILTER_OTHER);
1109                 if (ret)
1110                         return ret;
1111         }
1112         return 0;
1113 }
1114
1115 static int kretprobe_event_define_fields(struct trace_event_call *event_call)
1116 {
1117         int ret, i;
1118         struct kretprobe_trace_entry_head field;
1119         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1120
1121         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1122         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1123         /* Set argument names as fields */
1124         for (i = 0; i < tk->tp.nr_args; i++) {
1125                 struct probe_arg *parg = &tk->tp.args[i];
1126
1127                 ret = trace_define_field(event_call, parg->type->fmttype,
1128                                          parg->name,
1129                                          sizeof(field) + parg->offset,
1130                                          parg->type->size,
1131                                          parg->type->is_signed,
1132                                          FILTER_OTHER);
1133                 if (ret)
1134                         return ret;
1135         }
1136         return 0;
1137 }
1138
1139 #ifdef CONFIG_PERF_EVENTS
1140
1141 /* Kprobe profile handler */
1142 static void
1143 kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
1144 {
1145         struct trace_event_call *call = &tk->tp.call;
1146         struct bpf_prog *prog = call->prog;
1147         struct kprobe_trace_entry_head *entry;
1148         struct hlist_head *head;
1149         int size, __size, dsize;
1150         int rctx;
1151
1152         if (prog && !trace_call_bpf(prog, regs))
1153                 return;
1154
1155         head = this_cpu_ptr(call->perf_events);
1156         if (hlist_empty(head))
1157                 return;
1158
1159         dsize = __get_data_size(&tk->tp, regs);
1160         __size = sizeof(*entry) + tk->tp.size + dsize;
1161         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1162         size -= sizeof(u32);
1163
1164         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1165         if (!entry)
1166                 return;
1167
1168         entry->ip = (unsigned long)tk->rp.kp.addr;
1169         memset(&entry[1], 0, dsize);
1170         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1171         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1172                               head, NULL);
1173 }
1174 NOKPROBE_SYMBOL(kprobe_perf_func);
1175
1176 /* Kretprobe profile handler */
1177 static void
1178 kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1179                     struct pt_regs *regs)
1180 {
1181         struct trace_event_call *call = &tk->tp.call;
1182         struct bpf_prog *prog = call->prog;
1183         struct kretprobe_trace_entry_head *entry;
1184         struct hlist_head *head;
1185         int size, __size, dsize;
1186         int rctx;
1187
1188         if (prog && !trace_call_bpf(prog, regs))
1189                 return;
1190
1191         head = this_cpu_ptr(call->perf_events);
1192         if (hlist_empty(head))
1193                 return;
1194
1195         dsize = __get_data_size(&tk->tp, regs);
1196         __size = sizeof(*entry) + tk->tp.size + dsize;
1197         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1198         size -= sizeof(u32);
1199
1200         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1201         if (!entry)
1202                 return;
1203
1204         entry->func = (unsigned long)tk->rp.kp.addr;
1205         entry->ret_ip = (unsigned long)ri->ret_addr;
1206         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1207         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1208                               head, NULL);
1209 }
1210 NOKPROBE_SYMBOL(kretprobe_perf_func);
1211 #endif  /* CONFIG_PERF_EVENTS */
1212
1213 /*
1214  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1215  *
1216  * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1217  * lockless, but we can't race with this __init function.
1218  */
1219 static int kprobe_register(struct trace_event_call *event,
1220                            enum trace_reg type, void *data)
1221 {
1222         struct trace_kprobe *tk = (struct trace_kprobe *)event->data;
1223         struct trace_event_file *file = data;
1224
1225         switch (type) {
1226         case TRACE_REG_REGISTER:
1227                 return enable_trace_kprobe(tk, file);
1228         case TRACE_REG_UNREGISTER:
1229                 return disable_trace_kprobe(tk, file);
1230
1231 #ifdef CONFIG_PERF_EVENTS
1232         case TRACE_REG_PERF_REGISTER:
1233                 return enable_trace_kprobe(tk, NULL);
1234         case TRACE_REG_PERF_UNREGISTER:
1235                 return disable_trace_kprobe(tk, NULL);
1236         case TRACE_REG_PERF_OPEN:
1237         case TRACE_REG_PERF_CLOSE:
1238         case TRACE_REG_PERF_ADD:
1239         case TRACE_REG_PERF_DEL:
1240                 return 0;
1241 #endif
1242         }
1243         return 0;
1244 }
1245
1246 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1247 {
1248         struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
1249
1250         raw_cpu_inc(*tk->nhit);
1251
1252         if (tk->tp.flags & TP_FLAG_TRACE)
1253                 kprobe_trace_func(tk, regs);
1254 #ifdef CONFIG_PERF_EVENTS
1255         if (tk->tp.flags & TP_FLAG_PROFILE)
1256                 kprobe_perf_func(tk, regs);
1257 #endif
1258         return 0;       /* We don't tweek kernel, so just return 0 */
1259 }
1260 NOKPROBE_SYMBOL(kprobe_dispatcher);
1261
1262 static int
1263 kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1264 {
1265         struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
1266
1267         raw_cpu_inc(*tk->nhit);
1268
1269         if (tk->tp.flags & TP_FLAG_TRACE)
1270                 kretprobe_trace_func(tk, ri, regs);
1271 #ifdef CONFIG_PERF_EVENTS
1272         if (tk->tp.flags & TP_FLAG_PROFILE)
1273                 kretprobe_perf_func(tk, ri, regs);
1274 #endif
1275         return 0;       /* We don't tweek kernel, so just return 0 */
1276 }
1277 NOKPROBE_SYMBOL(kretprobe_dispatcher);
1278
1279 static struct trace_event_functions kretprobe_funcs = {
1280         .trace          = print_kretprobe_event
1281 };
1282
1283 static struct trace_event_functions kprobe_funcs = {
1284         .trace          = print_kprobe_event
1285 };
1286
1287 static int register_kprobe_event(struct trace_kprobe *tk)
1288 {
1289         struct trace_event_call *call = &tk->tp.call;
1290         int ret;
1291
1292         /* Initialize trace_event_call */
1293         INIT_LIST_HEAD(&call->class->fields);
1294         if (trace_kprobe_is_return(tk)) {
1295                 call->event.funcs = &kretprobe_funcs;
1296                 call->class->define_fields = kretprobe_event_define_fields;
1297         } else {
1298                 call->event.funcs = &kprobe_funcs;
1299                 call->class->define_fields = kprobe_event_define_fields;
1300         }
1301         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
1302                 return -ENOMEM;
1303         ret = register_trace_event(&call->event);
1304         if (!ret) {
1305                 kfree(call->print_fmt);
1306                 return -ENODEV;
1307         }
1308         call->flags = TRACE_EVENT_FL_KPROBE;
1309         call->class->reg = kprobe_register;
1310         call->data = tk;
1311         ret = trace_add_event_call(call);
1312         if (ret) {
1313                 pr_info("Failed to register kprobe event: %s\n",
1314                         trace_event_name(call));
1315                 kfree(call->print_fmt);
1316                 unregister_trace_event(&call->event);
1317         }
1318         return ret;
1319 }
1320
1321 static int unregister_kprobe_event(struct trace_kprobe *tk)
1322 {
1323         int ret;
1324
1325         /* tp->event is unregistered in trace_remove_event_call() */
1326         ret = trace_remove_event_call(&tk->tp.call);
1327         if (!ret)
1328                 kfree(tk->tp.call.print_fmt);
1329         return ret;
1330 }
1331
1332 /* Make a tracefs interface for controlling probe points */
1333 static __init int init_kprobe_trace(void)
1334 {
1335         struct dentry *d_tracer;
1336         struct dentry *entry;
1337
1338         if (register_module_notifier(&trace_kprobe_module_nb))
1339                 return -EINVAL;
1340
1341         d_tracer = tracing_init_dentry();
1342         if (IS_ERR(d_tracer))
1343                 return 0;
1344
1345         entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
1346                                     NULL, &kprobe_events_ops);
1347
1348         /* Event list interface */
1349         if (!entry)
1350                 pr_warn("Could not create tracefs 'kprobe_events' entry\n");
1351
1352         /* Profile interface */
1353         entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
1354                                     NULL, &kprobe_profile_ops);
1355
1356         if (!entry)
1357                 pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
1358         return 0;
1359 }
1360 fs_initcall(init_kprobe_trace);
1361
1362
1363 #ifdef CONFIG_FTRACE_STARTUP_TEST
1364 /*
1365  * The "__used" keeps gcc from removing the function symbol
1366  * from the kallsyms table. 'noinline' makes sure that there
1367  * isn't an inlined version used by the test method below
1368  */
1369 static __used __init noinline int
1370 kprobe_trace_selftest_target(int a1, int a2, int a3, int a4, int a5, int a6)
1371 {
1372         return a1 + a2 + a3 + a4 + a5 + a6;
1373 }
1374
1375 static struct __init trace_event_file *
1376 find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
1377 {
1378         struct trace_event_file *file;
1379
1380         list_for_each_entry(file, &tr->events, list)
1381                 if (file->event_call == &tk->tp.call)
1382                         return file;
1383
1384         return NULL;
1385 }
1386
1387 /*
1388  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
1389  * stage, we can do this lockless.
1390  */
1391 static __init int kprobe_trace_self_tests_init(void)
1392 {
1393         int ret, warn = 0;
1394         int (*target)(int, int, int, int, int, int);
1395         struct trace_kprobe *tk;
1396         struct trace_event_file *file;
1397
1398         if (tracing_is_disabled())
1399                 return -ENODEV;
1400
1401         target = kprobe_trace_selftest_target;
1402
1403         pr_info("Testing kprobe tracing: ");
1404
1405         ret = traceprobe_command("p:testprobe kprobe_trace_selftest_target "
1406                                   "$stack $stack0 +0($stack)",
1407                                   create_trace_kprobe);
1408         if (WARN_ON_ONCE(ret)) {
1409                 pr_warn("error on probing function entry.\n");
1410                 warn++;
1411         } else {
1412                 /* Enable trace point */
1413                 tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1414                 if (WARN_ON_ONCE(tk == NULL)) {
1415                         pr_warn("error on getting new probe.\n");
1416                         warn++;
1417                 } else {
1418                         file = find_trace_probe_file(tk, top_trace_array());
1419                         if (WARN_ON_ONCE(file == NULL)) {
1420                                 pr_warn("error on getting probe file.\n");
1421                                 warn++;
1422                         } else
1423                                 enable_trace_kprobe(tk, file);
1424                 }
1425         }
1426
1427         ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
1428                                   "$retval", create_trace_kprobe);
1429         if (WARN_ON_ONCE(ret)) {
1430                 pr_warn("error on probing function return.\n");
1431                 warn++;
1432         } else {
1433                 /* Enable trace point */
1434                 tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1435                 if (WARN_ON_ONCE(tk == NULL)) {
1436                         pr_warn("error on getting 2nd new probe.\n");
1437                         warn++;
1438                 } else {
1439                         file = find_trace_probe_file(tk, top_trace_array());
1440                         if (WARN_ON_ONCE(file == NULL)) {
1441                                 pr_warn("error on getting probe file.\n");
1442                                 warn++;
1443                         } else
1444                                 enable_trace_kprobe(tk, file);
1445                 }
1446         }
1447
1448         if (warn)
1449                 goto end;
1450
1451         ret = target(1, 2, 3, 4, 5, 6);
1452
1453         /*
1454          * Not expecting an error here, the check is only to prevent the
1455          * optimizer from removing the call to target() as otherwise there
1456          * are no side-effects and the call is never performed.
1457          */
1458         if (ret != 21)
1459                 warn++;
1460
1461         /* Disable trace points before removing it */
1462         tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1463         if (WARN_ON_ONCE(tk == NULL)) {
1464                 pr_warn("error on getting test probe.\n");
1465                 warn++;
1466         } else {
1467                 if (trace_kprobe_nhit(tk) != 1) {
1468                         pr_warn("incorrect number of testprobe hits\n");
1469                         warn++;
1470                 }
1471
1472                 file = find_trace_probe_file(tk, top_trace_array());
1473                 if (WARN_ON_ONCE(file == NULL)) {
1474                         pr_warn("error on getting probe file.\n");
1475                         warn++;
1476                 } else
1477                         disable_trace_kprobe(tk, file);
1478         }
1479
1480         tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1481         if (WARN_ON_ONCE(tk == NULL)) {
1482                 pr_warn("error on getting 2nd test probe.\n");
1483                 warn++;
1484         } else {
1485                 if (trace_kprobe_nhit(tk) != 1) {
1486                         pr_warn("incorrect number of testprobe2 hits\n");
1487                         warn++;
1488                 }
1489
1490                 file = find_trace_probe_file(tk, top_trace_array());
1491                 if (WARN_ON_ONCE(file == NULL)) {
1492                         pr_warn("error on getting probe file.\n");
1493                         warn++;
1494                 } else
1495                         disable_trace_kprobe(tk, file);
1496         }
1497
1498         ret = traceprobe_command("-:testprobe", create_trace_kprobe);
1499         if (WARN_ON_ONCE(ret)) {
1500                 pr_warn("error on deleting a probe.\n");
1501                 warn++;
1502         }
1503
1504         ret = traceprobe_command("-:testprobe2", create_trace_kprobe);
1505         if (WARN_ON_ONCE(ret)) {
1506                 pr_warn("error on deleting a probe.\n");
1507                 warn++;
1508         }
1509
1510 end:
1511         release_all_trace_kprobes();
1512         if (warn)
1513                 pr_cont("NG: Some tests are failed. Please check them.\n");
1514         else
1515                 pr_cont("OK\n");
1516         return 0;
1517 }
1518
1519 late_initcall(kprobe_trace_self_tests_init);
1520
1521 #endif