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 #define pr_fmt(fmt)     "trace_kprobe: " fmt
  20
  21 #include <linux/module.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/rculist.h>
  24 #include <linux/error-injection.h>
  25
  26 #include "trace_probe.h"
  27
  28 #define KPROBE_EVENT_SYSTEM "kprobes"
  29 #define KRETPROBE_MAXACTIVE_MAX 4096
  30
  31 /**
  32  * Kprobe event core functions
  33  */
  34 struct trace_kprobe {
  35         struct list_head        list;
  36         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
  37         unsigned long __percpu *nhit;
  38         const char              *symbol;        /* symbol name */
  39         struct trace_probe      tp;
  40 };
  41
  42 #define SIZEOF_TRACE_KPROBE(n)                          \
  43         (offsetof(struct trace_kprobe, tp.args) +       \
  44         (sizeof(struct probe_arg) * (n)))
  45
  46 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
  47 {
  48         return tk->rp.handler != NULL;
  49 }
  50
  51 static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
  52 {
  53         return tk->symbol ? tk->symbol : "unknown";
  54 }
  55
  56 static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
  57 {
  58         return tk->rp.kp.offset;
  59 }
  60
  61 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
  62 {
  63         return !!(kprobe_gone(&tk->rp.kp));
  64 }
  65
  66 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
  67                                                  struct module *mod)
  68 {
  69         int len = strlen(mod->name);
  70         const char *name = trace_kprobe_symbol(tk);
  71         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
  72 }
  73
  74 static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)
  75 {
  76         return !!strchr(trace_kprobe_symbol(tk), ':');
  77 }
  78
  79 static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
  80 {
  81         unsigned long nhit = 0;
  82         int cpu;
  83
  84         for_each_possible_cpu(cpu)
  85                 nhit += *per_cpu_ptr(tk->nhit, cpu);
  86
  87         return nhit;
  88 }
  89
  90 bool trace_kprobe_on_func_entry(struct trace_event_call *call)
  91 {
  92         struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
  93
  94         return kprobe_on_func_entry(tk->rp.kp.addr,
  95                         tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
  96                         tk->rp.kp.addr ? 0 : tk->rp.kp.offset);
  97 }
  98
  99 bool trace_kprobe_error_injectable(struct trace_event_call *call)
 100 {
 101         struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
 102         unsigned long addr;
 103
 104         if (tk->symbol) {
 105                 addr = (unsigned long)
 106                         kallsyms_lookup_name(trace_kprobe_symbol(tk));
 107                 addr += tk->rp.kp.offset;
 108         } else {
 109                 addr = (unsigned long)tk->rp.kp.addr;
 110         }
 111         return within_error_injection_list(addr);
 112 }
 113
 114 static int register_kprobe_event(struct trace_kprobe *tk);
 115 static int unregister_kprobe_event(struct trace_kprobe *tk);
 116
 117 static DEFINE_MUTEX(probe_lock);
 118 static LIST_HEAD(probe_list);
 119
 120 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 121 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 122                                 struct pt_regs *regs);
 123
 124 /* Memory fetching by symbol */
 125 struct symbol_cache {
 126         char            *symbol;
 127         long            offset;
 128         unsigned long   addr;
 129 };
 130
 131 unsigned long update_symbol_cache(struct symbol_cache *sc)
 132 {
 133         sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
 134
 135         if (sc->addr)
 136                 sc->addr += sc->offset;
 137
 138         return sc->addr;
 139 }
 140
 141 void free_symbol_cache(struct symbol_cache *sc)
 142 {
 143         kfree(sc->symbol);
 144         kfree(sc);
 145 }
 146
 147 struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
 148 {
 149         struct symbol_cache *sc;
 150
 151         if (!sym || strlen(sym) == 0)
 152                 return NULL;
 153
 154         sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
 155         if (!sc)
 156                 return NULL;
 157
 158         sc->symbol = kstrdup(sym, GFP_KERNEL);
 159         if (!sc->symbol) {
 160                 kfree(sc);
 161                 return NULL;
 162         }
 163         sc->offset = offset;
 164         update_symbol_cache(sc);
 165
 166         return sc;
 167 }
 168
 169 /*
 170  * Kprobes-specific fetch functions
 171  */
 172 #define DEFINE_FETCH_stack(type)                                        \
 173 static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,          \
 174                                           void *offset, void *dest)     \
 175 {                                                                       \
 176         *(type *)dest = (type)regs_get_kernel_stack_nth(regs,           \
 177                                 (unsigned int)((unsigned long)offset)); \
 178 }                                                                       \
 179 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
 180
 181 DEFINE_BASIC_FETCH_FUNCS(stack)
 182 /* No string on the stack entry */
 183 #define fetch_stack_string      NULL
 184 #define fetch_stack_string_size NULL
 185
 186 #define DEFINE_FETCH_memory(type)                                       \
 187 static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,         \
 188                                           void *addr, void *dest)       \
 189 {                                                                       \
 190         type retval;                                                    \
 191         if (probe_kernel_address(addr, retval))                         \
 192                 *(type *)dest = 0;                                      \
 193         else                                                            \
 194                 *(type *)dest = retval;                                 \
 195 }                                                                       \
 196 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
 197
 198 DEFINE_BASIC_FETCH_FUNCS(memory)
 199 /*
 200  * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 201  * length and relative data location.
 202  */
 203 static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
 204                                             void *addr, void *dest)
 205 {
 206         int maxlen = get_rloc_len(*(u32 *)dest);
 207         u8 *dst = get_rloc_data(dest);
 208         long ret;
 209
 210         if (!maxlen)
 211                 return;
 212
 213         /*
 214          * Try to get string again, since the string can be changed while
 215          * probing.
 216          */
 217         ret = strncpy_from_unsafe(dst, addr, maxlen);
 218
 219         if (ret < 0) {  /* Failed to fetch string */
 220                 dst[0] = '\0';
 221                 *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
 222         } else {
 223                 *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
 224         }
 225 }
 226 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
 227
 228 /* Return the length of string -- including null terminal byte */
 229 static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 230                                                  void *addr, void *dest)
 231 {
 232         mm_segment_t old_fs;
 233         int ret, len = 0;
 234         u8 c;
 235
 236         old_fs = get_fs();
 237         set_fs(KERNEL_DS);
 238         pagefault_disable();
 239
 240         do {
 241                 ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
 242                 len++;
 243         } while (c && ret == 0 && len < MAX_STRING_SIZE);
 244
 245         pagefault_enable();
 246         set_fs(old_fs);
 247
 248         if (ret < 0)    /* Failed to check the length */
 249                 *(u32 *)dest = 0;
 250         else
 251                 *(u32 *)dest = len;
 252 }
 253 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
 254
 255 #define DEFINE_FETCH_symbol(type)                                       \
 256 void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
 257 {                                                                       \
 258         struct symbol_cache *sc = data;                                 \
 259         if (sc->addr)                                                   \
 260                 fetch_memory_##type(regs, (void *)sc->addr, dest);      \
 261         else                                                            \
 262                 *(type *)dest = 0;                                      \
 263 }                                                                       \
 264 NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
 265
 266 DEFINE_BASIC_FETCH_FUNCS(symbol)
 267 DEFINE_FETCH_symbol(string)
 268 DEFINE_FETCH_symbol(string_size)
 269
 270 /* kprobes don't support file_offset fetch methods */
 271 #define fetch_file_offset_u8            NULL
 272 #define fetch_file_offset_u16           NULL
 273 #define fetch_file_offset_u32           NULL
 274 #define fetch_file_offset_u64           NULL
 275 #define fetch_file_offset_string        NULL
 276 #define fetch_file_offset_string_size   NULL
 277
 278 /* Fetch type information table */
 279 static const struct fetch_type kprobes_fetch_type_table[] = {
 280         /* Special types */
 281         [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
 282                                         sizeof(u32), 1, "__data_loc char[]"),
 283         [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
 284                                         string_size, sizeof(u32), 0, "u32"),
 285         /* Basic types */
 286         ASSIGN_FETCH_TYPE(u8,  u8,  0),
 287         ASSIGN_FETCH_TYPE(u16, u16, 0),
 288         ASSIGN_FETCH_TYPE(u32, u32, 0),
 289         ASSIGN_FETCH_TYPE(u64, u64, 0),
 290         ASSIGN_FETCH_TYPE(s8,  u8,  1),
 291         ASSIGN_FETCH_TYPE(s16, u16, 1),
 292         ASSIGN_FETCH_TYPE(s32, u32, 1),
 293         ASSIGN_FETCH_TYPE(s64, u64, 1),
 294         ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
 295         ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
 296         ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
 297         ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
 298
 299         ASSIGN_FETCH_TYPE_END
 300 };
 301
 302 /*
 303  * Allocate new trace_probe and initialize it (including kprobes).
 304  */
 305 static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 306                                              const char *event,
 307                                              void *addr,
 308                                              const char *symbol,
 309                                              unsigned long offs,
 310                                              int maxactive,
 311                                              int nargs, bool is_return)
 312 {
 313         struct trace_kprobe *tk;
 314         int ret = -ENOMEM;
 315
 316         tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
 317         if (!tk)
 318                 return ERR_PTR(ret);
 319
 320         tk->nhit = alloc_percpu(unsigned long);
 321         if (!tk->nhit)
 322                 goto error;
 323
 324         if (symbol) {
 325                 tk->symbol = kstrdup(symbol, GFP_KERNEL);
 326                 if (!tk->symbol)
 327                         goto error;
 328                 tk->rp.kp.symbol_name = tk->symbol;
 329                 tk->rp.kp.offset = offs;
 330         } else
 331                 tk->rp.kp.addr = addr;
 332
 333         if (is_return)
 334                 tk->rp.handler = kretprobe_dispatcher;
 335         else
 336                 tk->rp.kp.pre_handler = kprobe_dispatcher;
 337
 338         tk->rp.maxactive = maxactive;
 339
 340         if (!event || !is_good_name(event)) {
 341                 ret = -EINVAL;
 342                 goto error;
 343         }
 344
 345         tk->tp.call.class = &tk->tp.class;
 346         tk->tp.call.name = kstrdup(event, GFP_KERNEL);
 347         if (!tk->tp.call.name)
 348                 goto error;
 349
 350         if (!group || !is_good_name(group)) {
 351                 ret = -EINVAL;
 352                 goto error;
 353         }
 354
 355         tk->tp.class.system = kstrdup(group, GFP_KERNEL);
 356         if (!tk->tp.class.system)
 357                 goto error;
 358
 359         INIT_LIST_HEAD(&tk->list);
 360         INIT_LIST_HEAD(&tk->tp.files);
 361         return tk;
 362 error:
 363         kfree(tk->tp.call.name);
 364         kfree(tk->symbol);
 365         free_percpu(tk->nhit);
 366         kfree(tk);
 367         return ERR_PTR(ret);
 368 }
 369
 370 static void free_trace_kprobe(struct trace_kprobe *tk)
 371 {
 372         int i;
 373
 374         for (i = 0; i < tk->tp.nr_args; i++)
 375                 traceprobe_free_probe_arg(&tk->tp.args[i]);
 376
 377         kfree(tk->tp.call.class->system);
 378         kfree(tk->tp.call.name);
 379         kfree(tk->symbol);
 380         free_percpu(tk->nhit);
 381         kfree(tk);
 382 }
 383
 384 static struct trace_kprobe *find_trace_kprobe(const char *event,
 385                                               const char *group)
 386 {
 387         struct trace_kprobe *tk;
 388
 389         list_for_each_entry(tk, &probe_list, list)
 390                 if (strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
 391                     strcmp(tk->tp.call.class->system, group) == 0)
 392                         return tk;
 393         return NULL;
 394 }
 395
 396 /*
 397  * Enable trace_probe
 398  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
 399  */
 400 static int
 401 enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 402 {
 403         int ret = 0;
 404
 405         if (file) {
 406                 struct event_file_link *link;
 407
 408                 link = kmalloc(sizeof(*link), GFP_KERNEL);
 409                 if (!link) {
 410                         ret = -ENOMEM;
 411                         goto out;
 412                 }
 413
 414                 link->file = file;
 415                 list_add_tail_rcu(&link->list, &tk->tp.files);
 416
 417                 tk->tp.flags |= TP_FLAG_TRACE;
 418         } else
 419                 tk->tp.flags |= TP_FLAG_PROFILE;
 420
 421         if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
 422                 if (trace_kprobe_is_return(tk))
 423                         ret = enable_kretprobe(&tk->rp);
 424                 else
 425                         ret = enable_kprobe(&tk->rp.kp);
 426         }
 427  out:
 428         return ret;
 429 }
 430
 431 /*
 432  * Disable trace_probe
 433  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
 434  */
 435 static int
 436 disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 437 {
 438         struct event_file_link *link = NULL;
 439         int wait = 0;
 440         int ret = 0;
 441
 442         if (file) {
 443                 link = find_event_file_link(&tk->tp, file);
 444                 if (!link) {
 445                         ret = -EINVAL;
 446                         goto out;
 447                 }
 448
 449                 list_del_rcu(&link->list);
 450                 wait = 1;
 451                 if (!list_empty(&tk->tp.files))
 452                         goto out;
 453
 454                 tk->tp.flags &= ~TP_FLAG_TRACE;
 455         } else
 456                 tk->tp.flags &= ~TP_FLAG_PROFILE;
 457
 458         if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
 459                 if (trace_kprobe_is_return(tk))
 460                         disable_kretprobe(&tk->rp);
 461                 else
 462                         disable_kprobe(&tk->rp.kp);
 463                 wait = 1;
 464         }
 465
 466         /*
 467          * if tk is not added to any list, it must be a local trace_kprobe
 468          * created with perf_event_open. We don't need to wait for these
 469          * trace_kprobes
 470          */
 471         if (list_empty(&tk->list))
 472                 wait = 0;
 473  out:
 474         if (wait) {
 475                 /*
 476                  * Synchronize with kprobe_trace_func/kretprobe_trace_func
 477                  * to ensure disabled (all running handlers are finished).
 478                  * This is not only for kfree(), but also the caller,
 479                  * trace_remove_event_call() supposes it for releasing
 480                  * event_call related objects, which will be accessed in
 481                  * the kprobe_trace_func/kretprobe_trace_func.
 482                  */
 483                 synchronize_sched();
 484                 kfree(link);    /* Ignored if link == NULL */
 485         }
 486
 487         return ret;
 488 }
 489
 490 /* Internal register function - just handle k*probes and flags */
 491 static int __register_trace_kprobe(struct trace_kprobe *tk)
 492 {
 493         int i, ret;
 494
 495         if (trace_probe_is_registered(&tk->tp))
 496                 return -EINVAL;
 497
 498         for (i = 0; i < tk->tp.nr_args; i++)
 499                 traceprobe_update_arg(&tk->tp.args[i]);
 500
 501         /* Set/clear disabled flag according to tp->flag */
 502         if (trace_probe_is_enabled(&tk->tp))
 503                 tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
 504         else
 505                 tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
 506
 507         if (trace_kprobe_is_return(tk))
 508                 ret = register_kretprobe(&tk->rp);
 509         else
 510                 ret = register_kprobe(&tk->rp.kp);
 511
 512         if (ret == 0)
 513                 tk->tp.flags |= TP_FLAG_REGISTERED;
 514         else {
 515                 if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
 516                         pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
 517                         ret = 0;
 518                 } else if (ret == -EILSEQ) {
 519                         pr_warn("Probing address(0x%p) is not an instruction boundary.\n",
 520                                 tk->rp.kp.addr);
 521                         ret = -EINVAL;
 522                 }
 523         }
 524
 525         return ret;
 526 }
 527
 528 /* Internal unregister function - just handle k*probes and flags */
 529 static void __unregister_trace_kprobe(struct trace_kprobe *tk)
 530 {
 531         if (trace_probe_is_registered(&tk->tp)) {
 532                 if (trace_kprobe_is_return(tk))
 533                         unregister_kretprobe(&tk->rp);
 534                 else
 535                         unregister_kprobe(&tk->rp.kp);
 536                 tk->tp.flags &= ~TP_FLAG_REGISTERED;
 537                 /* Cleanup kprobe for reuse */
 538                 if (tk->rp.kp.symbol_name)
 539                         tk->rp.kp.addr = NULL;
 540         }
 541 }
 542
 543 /* Unregister a trace_probe and probe_event: call with locking probe_lock */
 544 static int unregister_trace_kprobe(struct trace_kprobe *tk)
 545 {
 546         /* Enabled event can not be unregistered */
 547         if (trace_probe_is_enabled(&tk->tp))
 548                 return -EBUSY;
 549
 550         /* Will fail if probe is being used by ftrace or perf */
 551         if (unregister_kprobe_event(tk))
 552                 return -EBUSY;
 553
 554         __unregister_trace_kprobe(tk);
 555         list_del(&tk->list);
 556
 557         return 0;
 558 }
 559
 560 /* Register a trace_probe and probe_event */
 561 static int register_trace_kprobe(struct trace_kprobe *tk)
 562 {
 563         struct trace_kprobe *old_tk;
 564         int ret;
 565
 566         mutex_lock(&probe_lock);
 567
 568         /* Delete old (same name) event if exist */
 569         old_tk = find_trace_kprobe(trace_event_name(&tk->tp.call),
 570                         tk->tp.call.class->system);
 571         if (old_tk) {
 572                 ret = unregister_trace_kprobe(old_tk);
 573                 if (ret < 0)
 574                         goto end;
 575                 free_trace_kprobe(old_tk);
 576         }
 577
 578         /* Register new event */
 579         ret = register_kprobe_event(tk);
 580         if (ret) {
 581                 pr_warn("Failed to register probe event(%d)\n", ret);
 582                 goto end;
 583         }
 584
 585         /* Register k*probe */
 586         ret = __register_trace_kprobe(tk);
 587         if (ret < 0)
 588                 unregister_kprobe_event(tk);
 589         else
 590                 list_add_tail(&tk->list, &probe_list);
 591
 592 end:
 593         mutex_unlock(&probe_lock);
 594         return ret;
 595 }
 596
 597 /* Module notifier call back, checking event on the module */
 598 static int trace_kprobe_module_callback(struct notifier_block *nb,
 599                                        unsigned long val, void *data)
 600 {
 601         struct module *mod = data;
 602         struct trace_kprobe *tk;
 603         int ret;
 604
 605         if (val != MODULE_STATE_COMING)
 606                 return NOTIFY_DONE;
 607
 608         /* Update probes on coming module */
 609         mutex_lock(&probe_lock);
 610         list_for_each_entry(tk, &probe_list, list) {
 611                 if (trace_kprobe_within_module(tk, mod)) {
 612                         /* Don't need to check busy - this should have gone. */
 613                         __unregister_trace_kprobe(tk);
 614                         ret = __register_trace_kprobe(tk);
 615                         if (ret)
 616                                 pr_warn("Failed to re-register probe %s on %s: %d\n",
 617                                         trace_event_name(&tk->tp.call),
 618                                         mod->name, ret);
 619                 }
 620         }
 621         mutex_unlock(&probe_lock);
 622
 623         return NOTIFY_DONE;
 624 }
 625
 626 static struct notifier_block trace_kprobe_module_nb = {
 627         .notifier_call = trace_kprobe_module_callback,
 628         .priority = 1   /* Invoked after kprobe module callback */
 629 };
 630
 631 /* Convert certain expected symbols into '_' when generating event names */
 632 static inline void sanitize_event_name(char *name)
 633 {
 634         while (*name++ != '\0')
 635                 if (*name == ':' || *name == '.')
 636                         *name = '_';
 637 }
 638
 639 static int create_trace_kprobe(int argc, char **argv)
 640 {
 641         /*
 642          * Argument syntax:
 643          *  - Add kprobe:
 644          *      p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
 645          *  - Add kretprobe:
 646          *      r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
 647          * Fetch args:
 648          *  $retval     : fetch return value
 649          *  $stack      : fetch stack address
 650          *  $stackN     : fetch Nth of stack (N:0-)
 651          *  $comm       : fetch current task comm
 652          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
 653          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 654          *  %REG        : fetch register REG
 655          * Dereferencing memory fetch:
 656          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
 657          * Alias name of args:
 658          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
 659          * Type of args:
 660          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 661          */
 662         struct trace_kprobe *tk;
 663         int i, ret = 0;
 664         bool is_return = false, is_delete = false;
 665         char *symbol = NULL, *event = NULL, *group = NULL;
 666         int maxactive = 0;
 667         char *arg;
 668         long offset = 0;
 669         void *addr = NULL;
 670         char buf[MAX_EVENT_NAME_LEN];
 671
 672         /* argc must be >= 1 */
 673         if (argv[0][0] == 'p')
 674                 is_return = false;
 675         else if (argv[0][0] == 'r')
 676                 is_return = true;
 677         else if (argv[0][0] == '-')
 678                 is_delete = true;
 679         else {
 680                 pr_info("Probe definition must be started with 'p', 'r' or"
 681                         " '-'.\n");
 682                 return -EINVAL;
 683         }
 684
 685         event = strchr(&argv[0][1], ':');
 686         if (event) {
 687                 event[0] = '\0';
 688                 event++;
 689         }
 690         if (is_return && isdigit(argv[0][1])) {
 691                 ret = kstrtouint(&argv[0][1], 0, &maxactive);
 692                 if (ret) {
 693                         pr_info("Failed to parse maxactive.\n");
 694                         return ret;
 695                 }
 696                 /* kretprobes instances are iterated over via a list. The
 697                  * maximum should stay reasonable.
 698                  */
 699                 if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
 700                         pr_info("Maxactive is too big (%d > %d).\n",
 701                                 maxactive, KRETPROBE_MAXACTIVE_MAX);
 702                         return -E2BIG;
 703                 }
 704         }
 705
 706         if (event) {
 707                 if (strchr(event, '/')) {
 708                         group = event;
 709                         event = strchr(group, '/') + 1;
 710                         event[-1] = '\0';
 711                         if (strlen(group) == 0) {
 712                                 pr_info("Group name is not specified\n");
 713                                 return -EINVAL;
 714                         }
 715                 }
 716                 if (strlen(event) == 0) {
 717                         pr_info("Event name is not specified\n");
 718                         return -EINVAL;
 719                 }
 720         }
 721         if (!group)
 722                 group = KPROBE_EVENT_SYSTEM;
 723
 724         if (is_delete) {
 725                 if (!event) {
 726                         pr_info("Delete command needs an event name.\n");
 727                         return -EINVAL;
 728                 }
 729                 mutex_lock(&probe_lock);
 730                 tk = find_trace_kprobe(event, group);
 731                 if (!tk) {
 732                         mutex_unlock(&probe_lock);
 733                         pr_info("Event %s/%s doesn't exist.\n", group, event);
 734                         return -ENOENT;
 735                 }
 736                 /* delete an event */
 737                 ret = unregister_trace_kprobe(tk);
 738                 if (ret == 0)
 739                         free_trace_kprobe(tk);
 740                 mutex_unlock(&probe_lock);
 741                 return ret;
 742         }
 743
 744         if (argc < 2) {
 745                 pr_info("Probe point is not specified.\n");
 746                 return -EINVAL;
 747         }
 748
 749         /* try to parse an address. if that fails, try to read the
 750          * input as a symbol. */
 751         if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
 752                 /* a symbol specified */
 753                 symbol = argv[1];
 754                 /* TODO: support .init module functions */
 755                 ret = traceprobe_split_symbol_offset(symbol, &offset);
 756                 if (ret || offset < 0 || offset > UINT_MAX) {
 757                         pr_info("Failed to parse either an address or a symbol.\n");
 758                         return ret;
 759                 }
 760                 if (offset && is_return &&
 761                     !kprobe_on_func_entry(NULL, symbol, offset)) {
 762                         pr_info("Given offset is not valid for return probe.\n");
 763                         return -EINVAL;
 764                 }
 765         }
 766         argc -= 2; argv += 2;
 767
 768         /* setup a probe */
 769         if (!event) {
 770                 /* Make a new event name */
 771                 if (symbol)
 772                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
 773                                  is_return ? 'r' : 'p', symbol, offset);
 774                 else
 775                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
 776                                  is_return ? 'r' : 'p', addr);
 777                 sanitize_event_name(buf);
 778                 event = buf;
 779         }
 780         tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
 781                                argc, is_return);
 782         if (IS_ERR(tk)) {
 783                 pr_info("Failed to allocate trace_probe.(%d)\n",
 784                         (int)PTR_ERR(tk));
 785                 return PTR_ERR(tk);
 786         }
 787
 788         /* parse arguments */
 789         ret = 0;
 790         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
 791                 struct probe_arg *parg = &tk->tp.args[i];
 792
 793                 /* Increment count for freeing args in error case */
 794                 tk->tp.nr_args++;
 795
 796                 /* Parse argument name */
 797                 arg = strchr(argv[i], '=');
 798                 if (arg) {
 799                         *arg++ = '\0';
 800                         parg->name = kstrdup(argv[i], GFP_KERNEL);
 801                 } else {
 802                         arg = argv[i];
 803                         /* If argument name is omitted, set "argN" */
 804                         snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
 805                         parg->name = kstrdup(buf, GFP_KERNEL);
 806                 }
 807
 808                 if (!parg->name) {
 809                         pr_info("Failed to allocate argument[%d] name.\n", i);
 810                         ret = -ENOMEM;
 811                         goto error;
 812                 }
 813
 814                 if (!is_good_name(parg->name)) {
 815                         pr_info("Invalid argument[%d] name: %s\n",
 816                                 i, parg->name);
 817                         ret = -EINVAL;
 818                         goto error;
 819                 }
 820
 821                 if (traceprobe_conflict_field_name(parg->name,
 822                                                         tk->tp.args, i)) {
 823                         pr_info("Argument[%d] name '%s' conflicts with "
 824                                 "another field.\n", i, argv[i]);
 825                         ret = -EINVAL;
 826                         goto error;
 827                 }
 828
 829                 /* Parse fetch argument */
 830                 ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
 831                                                 is_return, true,
 832                                                 kprobes_fetch_type_table);
 833                 if (ret) {
 834                         pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
 835                         goto error;
 836                 }
 837         }
 838
 839         ret = register_trace_kprobe(tk);
 840         if (ret)
 841                 goto error;
 842         return 0;
 843
 844 error:
 845         free_trace_kprobe(tk);
 846         return ret;
 847 }
 848
 849 static int release_all_trace_kprobes(void)
 850 {
 851         struct trace_kprobe *tk;
 852         int ret = 0;
 853
 854         mutex_lock(&probe_lock);
 855         /* Ensure no probe is in use. */
 856         list_for_each_entry(tk, &probe_list, list)
 857                 if (trace_probe_is_enabled(&tk->tp)) {
 858                         ret = -EBUSY;
 859                         goto end;
 860                 }
 861         /* TODO: Use batch unregistration */
 862         while (!list_empty(&probe_list)) {
 863                 tk = list_entry(probe_list.next, struct trace_kprobe, list);
 864                 ret = unregister_trace_kprobe(tk);
 865                 if (ret)
 866                         goto end;
 867                 free_trace_kprobe(tk);
 868         }
 869
 870 end:
 871         mutex_unlock(&probe_lock);
 872
 873         return ret;
 874 }
 875
 876 /* Probes listing interfaces */
 877 static void *probes_seq_start(struct seq_file *m, loff_t *pos)
 878 {
 879         mutex_lock(&probe_lock);
 880         return seq_list_start(&probe_list, *pos);
 881 }
 882
 883 static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
 884 {
 885         return seq_list_next(v, &probe_list, pos);
 886 }
 887
 888 static void probes_seq_stop(struct seq_file *m, void *v)
 889 {
 890         mutex_unlock(&probe_lock);
 891 }
 892
 893 static int probes_seq_show(struct seq_file *m, void *v)
 894 {
 895         struct trace_kprobe *tk = v;
 896         int i;
 897
 898         seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
 899         seq_printf(m, ":%s/%s", tk->tp.call.class->system,
 900                         trace_event_name(&tk->tp.call));
 901
 902         if (!tk->symbol)
 903                 seq_printf(m, " 0x%p", tk->rp.kp.addr);
 904         else if (tk->rp.kp.offset)
 905                 seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
 906                            tk->rp.kp.offset);
 907         else
 908                 seq_printf(m, " %s", trace_kprobe_symbol(tk));
 909
 910         for (i = 0; i < tk->tp.nr_args; i++)
 911                 seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
 912         seq_putc(m, '\n');
 913
 914         return 0;
 915 }
 916
 917 static const struct seq_operations probes_seq_op = {
 918         .start  = probes_seq_start,
 919         .next   = probes_seq_next,
 920         .stop   = probes_seq_stop,
 921         .show   = probes_seq_show
 922 };
 923
 924 static int probes_open(struct inode *inode, struct file *file)
 925 {
 926         int ret;
 927
 928         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 929                 ret = release_all_trace_kprobes();
 930                 if (ret < 0)
 931                         return ret;
 932         }
 933
 934         return seq_open(file, &probes_seq_op);
 935 }
 936
 937 static ssize_t probes_write(struct file *file, const char __user *buffer,
 938                             size_t count, loff_t *ppos)
 939 {
 940         return trace_parse_run_command(file, buffer, count, ppos,
 941                                        create_trace_kprobe);
 942 }
 943
 944 static const struct file_operations kprobe_events_ops = {
 945         .owner          = THIS_MODULE,
 946         .open           = probes_open,
 947         .read           = seq_read,
 948         .llseek         = seq_lseek,
 949         .release        = seq_release,
 950         .write          = probes_write,
 951 };
 952
 953 /* Probes profiling interfaces */
 954 static int probes_profile_seq_show(struct seq_file *m, void *v)
 955 {
 956         struct trace_kprobe *tk = v;
 957
 958         seq_printf(m, "  %-44s %15lu %15lu\n",
 959                    trace_event_name(&tk->tp.call),
 960                    trace_kprobe_nhit(tk),
 961                    tk->rp.kp.nmissed);
 962
 963         return 0;
 964 }
 965
 966 static const struct seq_operations profile_seq_op = {
 967         .start  = probes_seq_start,
 968         .next   = probes_seq_next,
 969         .stop   = probes_seq_stop,
 970         .show   = probes_profile_seq_show
 971 };
 972
 973 static int profile_open(struct inode *inode, struct file *file)
 974 {
 975         return seq_open(file, &profile_seq_op);
 976 }
 977
 978 static const struct file_operations kprobe_profile_ops = {
 979         .owner          = THIS_MODULE,
 980         .open           = profile_open,
 981         .read           = seq_read,
 982         .llseek         = seq_lseek,
 983         .release        = seq_release,
 984 };
 985
 986 /* Kprobe handler */
 987 static nokprobe_inline void
 988 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
 989                     struct trace_event_file *trace_file)
 990 {
 991         struct kprobe_trace_entry_head *entry;
 992         struct ring_buffer_event *event;
 993         struct ring_buffer *buffer;
 994         int size, dsize, pc;
 995         unsigned long irq_flags;
 996         struct trace_event_call *call = &tk->tp.call;
 997
 998         WARN_ON(call != trace_file->event_call);
 999
1000         if (trace_trigger_soft_disabled(trace_file))
1001                 return;
1002
1003         local_save_flags(irq_flags);
1004         pc = preempt_count();
1005
1006         dsize = __get_data_size(&tk->tp, regs);
1007         size = sizeof(*entry) + tk->tp.size + dsize;
1008
1009         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1010                                                 call->event.type,
1011                                                 size, irq_flags, pc);
1012         if (!event)
1013                 return;
1014
1015         entry = ring_buffer_event_data(event);
1016         entry->ip = (unsigned long)tk->rp.kp.addr;
1017         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1018
1019         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1020                                          entry, irq_flags, pc, regs);
1021 }
1022
1023 static void
1024 kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
1025 {
1026         struct event_file_link *link;
1027
1028         list_for_each_entry_rcu(link, &tk->tp.files, list)
1029                 __kprobe_trace_func(tk, regs, link->file);
1030 }
1031 NOKPROBE_SYMBOL(kprobe_trace_func);
1032
1033 /* Kretprobe handler */
1034 static nokprobe_inline void
1035 __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1036                        struct pt_regs *regs,
1037                        struct trace_event_file *trace_file)
1038 {
1039         struct kretprobe_trace_entry_head *entry;
1040         struct ring_buffer_event *event;
1041         struct ring_buffer *buffer;
1042         int size, pc, dsize;
1043         unsigned long irq_flags;
1044         struct trace_event_call *call = &tk->tp.call;
1045
1046         WARN_ON(call != trace_file->event_call);
1047
1048         if (trace_trigger_soft_disabled(trace_file))
1049                 return;
1050
1051         local_save_flags(irq_flags);
1052         pc = preempt_count();
1053
1054         dsize = __get_data_size(&tk->tp, regs);
1055         size = sizeof(*entry) + tk->tp.size + dsize;
1056
1057         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1058                                                 call->event.type,
1059                                                 size, irq_flags, pc);
1060         if (!event)
1061                 return;
1062
1063         entry = ring_buffer_event_data(event);
1064         entry->func = (unsigned long)tk->rp.kp.addr;
1065         entry->ret_ip = (unsigned long)ri->ret_addr;
1066         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1067
1068         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1069                                          entry, irq_flags, pc, regs);
1070 }
1071
1072 static void
1073 kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1074                      struct pt_regs *regs)
1075 {
1076         struct event_file_link *link;
1077
1078         list_for_each_entry_rcu(link, &tk->tp.files, list)
1079                 __kretprobe_trace_func(tk, ri, regs, link->file);
1080 }
1081 NOKPROBE_SYMBOL(kretprobe_trace_func);
1082
1083 /* Event entry printers */
1084 static enum print_line_t
1085 print_kprobe_event(struct trace_iterator *iter, int flags,
1086                    struct trace_event *event)
1087 {
1088         struct kprobe_trace_entry_head *field;
1089         struct trace_seq *s = &iter->seq;
1090         struct trace_probe *tp;
1091         u8 *data;
1092         int i;
1093
1094         field = (struct kprobe_trace_entry_head *)iter->ent;
1095         tp = container_of(event, struct trace_probe, call.event);
1096
1097         trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
1098
1099         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
1100                 goto out;
1101
1102         trace_seq_putc(s, ')');
1103
1104         data = (u8 *)&field[1];
1105         for (i = 0; i < tp->nr_args; i++)
1106                 if (!tp->args[i].type->print(s, tp->args[i].name,
1107                                              data + tp->args[i].offset, field))
1108                         goto out;
1109
1110         trace_seq_putc(s, '\n');
1111  out:
1112         return trace_handle_return(s);
1113 }
1114
1115 static enum print_line_t
1116 print_kretprobe_event(struct trace_iterator *iter, int flags,
1117                       struct trace_event *event)
1118 {
1119         struct kretprobe_trace_entry_head *field;
1120         struct trace_seq *s = &iter->seq;
1121         struct trace_probe *tp;
1122         u8 *data;
1123         int i;
1124
1125         field = (struct kretprobe_trace_entry_head *)iter->ent;
1126         tp = container_of(event, struct trace_probe, call.event);
1127
1128         trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
1129
1130         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
1131                 goto out;
1132
1133         trace_seq_puts(s, " <- ");
1134
1135         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
1136                 goto out;
1137
1138         trace_seq_putc(s, ')');
1139
1140         data = (u8 *)&field[1];
1141         for (i = 0; i < tp->nr_args; i++)
1142                 if (!tp->args[i].type->print(s, tp->args[i].name,
1143                                              data + tp->args[i].offset, field))
1144                         goto out;
1145
1146         trace_seq_putc(s, '\n');
1147
1148  out:
1149         return trace_handle_return(s);
1150 }
1151
1152
1153 static int kprobe_event_define_fields(struct trace_event_call *event_call)
1154 {
1155         int ret, i;
1156         struct kprobe_trace_entry_head field;
1157         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1158
1159         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
1160         /* Set argument names as fields */
1161         for (i = 0; i < tk->tp.nr_args; i++) {
1162                 struct probe_arg *parg = &tk->tp.args[i];
1163
1164                 ret = trace_define_field(event_call, parg->type->fmttype,
1165                                          parg->name,
1166                                          sizeof(field) + parg->offset,
1167                                          parg->type->size,
1168                                          parg->type->is_signed,
1169                                          FILTER_OTHER);
1170                 if (ret)
1171                         return ret;
1172         }
1173         return 0;
1174 }
1175
1176 static int kretprobe_event_define_fields(struct trace_event_call *event_call)
1177 {
1178         int ret, i;
1179         struct kretprobe_trace_entry_head field;
1180         struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
1181
1182         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1183         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1184         /* Set argument names as fields */
1185         for (i = 0; i < tk->tp.nr_args; i++) {
1186                 struct probe_arg *parg = &tk->tp.args[i];
1187
1188                 ret = trace_define_field(event_call, parg->type->fmttype,
1189                                          parg->name,
1190                                          sizeof(field) + parg->offset,
1191                                          parg->type->size,
1192                                          parg->type->is_signed,
1193                                          FILTER_OTHER);
1194                 if (ret)
1195                         return ret;
1196         }
1197         return 0;
1198 }
1199
1200 #ifdef CONFIG_PERF_EVENTS
1201
1202 /* Kprobe profile handler */
1203 static int
1204 kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
1205 {
1206         struct trace_event_call *call = &tk->tp.call;
1207         struct kprobe_trace_entry_head *entry;
1208         struct hlist_head *head;
1209         int size, __size, dsize;
1210         int rctx;
1211
1212         if (bpf_prog_array_valid(call)) {
1213                 unsigned long orig_ip = instruction_pointer(regs);
1214                 int ret;
1215
1216                 ret = trace_call_bpf(call, regs);
1217
1218                 /*
1219                  * We need to check and see if we modified the pc of the
1220                  * pt_regs, and if so clear the kprobe and return 1 so that we
1221                  * don't do the single stepping.
1222                  * The ftrace kprobe handler leaves it up to us to re-enable
1223                  * preemption here before returning if we've modified the ip.
1224                  */
1225                 if (orig_ip != instruction_pointer(regs)) {
1226                         reset_current_kprobe();
1227                         preempt_enable_no_resched();
1228                         return 1;
1229                 }
1230                 if (!ret)
1231                         return 0;
1232         }
1233
1234         head = this_cpu_ptr(call->perf_events);
1235         if (hlist_empty(head))
1236                 return 0;
1237
1238         dsize = __get_data_size(&tk->tp, regs);
1239         __size = sizeof(*entry) + tk->tp.size + dsize;
1240         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1241         size -= sizeof(u32);
1242
1243         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1244         if (!entry)
1245                 return 0;
1246
1247         entry->ip = (unsigned long)tk->rp.kp.addr;
1248         memset(&entry[1], 0, dsize);
1249         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1250         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1251                               head, NULL);
1252         return 0;
1253 }
1254 NOKPROBE_SYMBOL(kprobe_perf_func);
1255
1256 /* Kretprobe profile handler */
1257 static void
1258 kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1259                     struct pt_regs *regs)
1260 {
1261         struct trace_event_call *call = &tk->tp.call;
1262         struct kretprobe_trace_entry_head *entry;
1263         struct hlist_head *head;
1264         int size, __size, dsize;
1265         int rctx;
1266
1267         if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
1268                 return;
1269
1270         head = this_cpu_ptr(call->perf_events);
1271         if (hlist_empty(head))
1272                 return;
1273
1274         dsize = __get_data_size(&tk->tp, regs);
1275         __size = sizeof(*entry) + tk->tp.size + dsize;
1276         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1277         size -= sizeof(u32);
1278
1279         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1280         if (!entry)
1281                 return;
1282
1283         entry->func = (unsigned long)tk->rp.kp.addr;
1284         entry->ret_ip = (unsigned long)ri->ret_addr;
1285         store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
1286         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1287                               head, NULL);
1288 }
1289 NOKPROBE_SYMBOL(kretprobe_perf_func);
1290 #endif  /* CONFIG_PERF_EVENTS */
1291
1292 /*
1293  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1294  *
1295  * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1296  * lockless, but we can't race with this __init function.
1297  */
1298 static int kprobe_register(struct trace_event_call *event,
1299                            enum trace_reg type, void *data)
1300 {
1301         struct trace_kprobe *tk = (struct trace_kprobe *)event->data;
1302         struct trace_event_file *file = data;
1303
1304         switch (type) {
1305         case TRACE_REG_REGISTER:
1306                 return enable_trace_kprobe(tk, file);
1307         case TRACE_REG_UNREGISTER:
1308                 return disable_trace_kprobe(tk, file);
1309
1310 #ifdef CONFIG_PERF_EVENTS
1311         case TRACE_REG_PERF_REGISTER:
1312                 return enable_trace_kprobe(tk, NULL);
1313         case TRACE_REG_PERF_UNREGISTER:
1314                 return disable_trace_kprobe(tk, NULL);
1315         case TRACE_REG_PERF_OPEN:
1316         case TRACE_REG_PERF_CLOSE:
1317         case TRACE_REG_PERF_ADD:
1318         case TRACE_REG_PERF_DEL:
1319                 return 0;
1320 #endif
1321         }
1322         return 0;
1323 }
1324
1325 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1326 {
1327         struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
1328         int ret = 0;
1329
1330         raw_cpu_inc(*tk->nhit);
1331
1332         if (tk->tp.flags & TP_FLAG_TRACE)
1333                 kprobe_trace_func(tk, regs);
1334 #ifdef CONFIG_PERF_EVENTS
1335         if (tk->tp.flags & TP_FLAG_PROFILE)
1336                 ret = kprobe_perf_func(tk, regs);
1337 #endif
1338         return ret;
1339 }
1340 NOKPROBE_SYMBOL(kprobe_dispatcher);
1341
1342 static int
1343 kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1344 {
1345         struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
1346
1347         raw_cpu_inc(*tk->nhit);
1348
1349         if (tk->tp.flags & TP_FLAG_TRACE)
1350                 kretprobe_trace_func(tk, ri, regs);
1351 #ifdef CONFIG_PERF_EVENTS
1352         if (tk->tp.flags & TP_FLAG_PROFILE)
1353                 kretprobe_perf_func(tk, ri, regs);
1354 #endif
1355         return 0;       /* We don't tweek kernel, so just return 0 */
1356 }
1357 NOKPROBE_SYMBOL(kretprobe_dispatcher);
1358
1359 static struct trace_event_functions kretprobe_funcs = {
1360         .trace          = print_kretprobe_event
1361 };
1362
1363 static struct trace_event_functions kprobe_funcs = {
1364         .trace          = print_kprobe_event
1365 };
1366
1367 static inline void init_trace_event_call(struct trace_kprobe *tk,
1368                                          struct trace_event_call *call)
1369 {
1370         INIT_LIST_HEAD(&call->class->fields);
1371         if (trace_kprobe_is_return(tk)) {
1372                 call->event.funcs = &kretprobe_funcs;
1373                 call->class->define_fields = kretprobe_event_define_fields;
1374         } else {
1375                 call->event.funcs = &kprobe_funcs;
1376                 call->class->define_fields = kprobe_event_define_fields;
1377         }
1378
1379         call->flags = TRACE_EVENT_FL_KPROBE;
1380         call->class->reg = kprobe_register;
1381         call->data = tk;
1382 }
1383
1384 static int register_kprobe_event(struct trace_kprobe *tk)
1385 {
1386         struct trace_event_call *call = &tk->tp.call;
1387         int ret = 0;
1388
1389         init_trace_event_call(tk, call);
1390
1391         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
1392                 return -ENOMEM;
1393         ret = register_trace_event(&call->event);
1394         if (!ret) {
1395                 kfree(call->print_fmt);
1396                 return -ENODEV;
1397         }
1398         ret = trace_add_event_call(call);
1399         if (ret) {
1400                 pr_info("Failed to register kprobe event: %s\n",
1401                         trace_event_name(call));
1402                 kfree(call->print_fmt);
1403                 unregister_trace_event(&call->event);
1404         }
1405         return ret;
1406 }
1407
1408 static int unregister_kprobe_event(struct trace_kprobe *tk)
1409 {
1410         int ret;
1411
1412         /* tp->event is unregistered in trace_remove_event_call() */
1413         ret = trace_remove_event_call(&tk->tp.call);
1414         if (!ret)
1415                 kfree(tk->tp.call.print_fmt);
1416         return ret;
1417 }
1418
1419 #ifdef CONFIG_PERF_EVENTS
1420 /* create a trace_kprobe, but don't add it to global lists */
1421 struct trace_event_call *
1422 create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
1423                           bool is_return)
1424 {
1425         struct trace_kprobe *tk;
1426         int ret;
1427         char *event;
1428
1429         /*
1430          * local trace_kprobes are not added to probe_list, so they are never
1431          * searched in find_trace_kprobe(). Therefore, there is no concern of
1432          * duplicated name here.
1433          */
1434         event = func ? func : "DUMMY_EVENT";
1435
1436         tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
1437                                 offs, 0 /* maxactive */, 0 /* nargs */,
1438                                 is_return);
1439
1440         if (IS_ERR(tk)) {
1441                 pr_info("Failed to allocate trace_probe.(%d)\n",
1442                         (int)PTR_ERR(tk));
1443                 return ERR_CAST(tk);
1444         }
1445
1446         init_trace_event_call(tk, &tk->tp.call);
1447
1448         if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
1449                 ret = -ENOMEM;
1450                 goto error;
1451         }
1452
1453         ret = __register_trace_kprobe(tk);
1454         if (ret < 0)
1455                 goto error;
1456
1457         return &tk->tp.call;
1458 error:
1459         free_trace_kprobe(tk);
1460         return ERR_PTR(ret);
1461 }
1462
1463 void destroy_local_trace_kprobe(struct trace_event_call *event_call)
1464 {
1465         struct trace_kprobe *tk;
1466
1467         tk = container_of(event_call, struct trace_kprobe, tp.call);
1468
1469         if (trace_probe_is_enabled(&tk->tp)) {
1470                 WARN_ON(1);
1471                 return;
1472         }
1473
1474         __unregister_trace_kprobe(tk);
1475         free_trace_kprobe(tk);
1476 }
1477 #endif /* CONFIG_PERF_EVENTS */
1478
1479 /* Make a tracefs interface for controlling probe points */
1480 static __init int init_kprobe_trace(void)
1481 {
1482         struct dentry *d_tracer;
1483         struct dentry *entry;
1484
1485         if (register_module_notifier(&trace_kprobe_module_nb))
1486                 return -EINVAL;
1487
1488         d_tracer = tracing_init_dentry();
1489         if (IS_ERR(d_tracer))
1490                 return 0;
1491
1492         entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
1493                                     NULL, &kprobe_events_ops);
1494
1495         /* Event list interface */
1496         if (!entry)
1497                 pr_warn("Could not create tracefs 'kprobe_events' entry\n");
1498
1499         /* Profile interface */
1500         entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
1501                                     NULL, &kprobe_profile_ops);
1502
1503         if (!entry)
1504                 pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
1505         return 0;
1506 }
1507 fs_initcall(init_kprobe_trace);
1508
1509
1510 #ifdef CONFIG_FTRACE_STARTUP_TEST
1511 /*
1512  * The "__used" keeps gcc from removing the function symbol
1513  * from the kallsyms table. 'noinline' makes sure that there
1514  * isn't an inlined version used by the test method below
1515  */
1516 static __used __init noinline int
1517 kprobe_trace_selftest_target(int a1, int a2, int a3, int a4, int a5, int a6)
1518 {
1519         return a1 + a2 + a3 + a4 + a5 + a6;
1520 }
1521
1522 static __init struct trace_event_file *
1523 find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
1524 {
1525         struct trace_event_file *file;
1526
1527         list_for_each_entry(file, &tr->events, list)
1528                 if (file->event_call == &tk->tp.call)
1529                         return file;
1530
1531         return NULL;
1532 }
1533
1534 /*
1535  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
1536  * stage, we can do this lockless.
1537  */
1538 static __init int kprobe_trace_self_tests_init(void)
1539 {
1540         int ret, warn = 0;
1541         int (*target)(int, int, int, int, int, int);
1542         struct trace_kprobe *tk;
1543         struct trace_event_file *file;
1544
1545         if (tracing_is_disabled())
1546                 return -ENODEV;
1547
1548         target = kprobe_trace_selftest_target;
1549
1550         pr_info("Testing kprobe tracing: ");
1551
1552         ret = trace_run_command("p:testprobe kprobe_trace_selftest_target "
1553                                 "$stack $stack0 +0($stack)",
1554                                 create_trace_kprobe);
1555         if (WARN_ON_ONCE(ret)) {
1556                 pr_warn("error on probing function entry.\n");
1557                 warn++;
1558         } else {
1559                 /* Enable trace point */
1560                 tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1561                 if (WARN_ON_ONCE(tk == NULL)) {
1562                         pr_warn("error on getting new probe.\n");
1563                         warn++;
1564                 } else {
1565                         file = find_trace_probe_file(tk, top_trace_array());
1566                         if (WARN_ON_ONCE(file == NULL)) {
1567                                 pr_warn("error on getting probe file.\n");
1568                                 warn++;
1569                         } else
1570                                 enable_trace_kprobe(tk, file);
1571                 }
1572         }
1573
1574         ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target "
1575                                 "$retval", create_trace_kprobe);
1576         if (WARN_ON_ONCE(ret)) {
1577                 pr_warn("error on probing function return.\n");
1578                 warn++;
1579         } else {
1580                 /* Enable trace point */
1581                 tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1582                 if (WARN_ON_ONCE(tk == NULL)) {
1583                         pr_warn("error on getting 2nd new probe.\n");
1584                         warn++;
1585                 } else {
1586                         file = find_trace_probe_file(tk, top_trace_array());
1587                         if (WARN_ON_ONCE(file == NULL)) {
1588                                 pr_warn("error on getting probe file.\n");
1589                                 warn++;
1590                         } else
1591                                 enable_trace_kprobe(tk, file);
1592                 }
1593         }
1594
1595         if (warn)
1596                 goto end;
1597
1598         ret = target(1, 2, 3, 4, 5, 6);
1599
1600         /*
1601          * Not expecting an error here, the check is only to prevent the
1602          * optimizer from removing the call to target() as otherwise there
1603          * are no side-effects and the call is never performed.
1604          */
1605         if (ret != 21)
1606                 warn++;
1607
1608         /* Disable trace points before removing it */
1609         tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1610         if (WARN_ON_ONCE(tk == NULL)) {
1611                 pr_warn("error on getting test probe.\n");
1612                 warn++;
1613         } else {
1614                 if (trace_kprobe_nhit(tk) != 1) {
1615                         pr_warn("incorrect number of testprobe hits\n");
1616                         warn++;
1617                 }
1618
1619                 file = find_trace_probe_file(tk, top_trace_array());
1620                 if (WARN_ON_ONCE(file == NULL)) {
1621                         pr_warn("error on getting probe file.\n");
1622                         warn++;
1623                 } else
1624                         disable_trace_kprobe(tk, file);
1625         }
1626
1627         tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1628         if (WARN_ON_ONCE(tk == NULL)) {
1629                 pr_warn("error on getting 2nd test probe.\n");
1630                 warn++;
1631         } else {
1632                 if (trace_kprobe_nhit(tk) != 1) {
1633                         pr_warn("incorrect number of testprobe2 hits\n");
1634                         warn++;
1635                 }
1636
1637                 file = find_trace_probe_file(tk, top_trace_array());
1638                 if (WARN_ON_ONCE(file == NULL)) {
1639                         pr_warn("error on getting probe file.\n");
1640                         warn++;
1641                 } else
1642                         disable_trace_kprobe(tk, file);
1643         }
1644
1645         ret = trace_run_command("-:testprobe", create_trace_kprobe);
1646         if (WARN_ON_ONCE(ret)) {
1647                 pr_warn("error on deleting a probe.\n");
1648                 warn++;
1649         }
1650
1651         ret = trace_run_command("-:testprobe2", create_trace_kprobe);
1652         if (WARN_ON_ONCE(ret)) {
1653                 pr_warn("error on deleting a probe.\n");
1654                 warn++;
1655         }
1656
1657 end:
1658         release_all_trace_kprobes();
1659         /*
1660          * Wait for the optimizer work to finish. Otherwise it might fiddle
1661          * with probes in already freed __init text.
1662          */
1663         wait_for_kprobe_optimizer();
1664         if (warn)
1665                 pr_cont("NG: Some tests are failed. Please check them.\n");
1666         else
1667                 pr_cont("OK\n");
1668         return 0;
1669 }
1670
1671 late_initcall(kprobe_trace_self_tests_init);
1672
1673 #endif