kernel/trace/trace_kprobe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Kprobes-based tracing events
   4  *
   5  * Created by Masami Hiramatsu <mhiramat@redhat.com>
   6  *
   7  */
   8 #define pr_fmt(fmt)     "trace_kprobe: " fmt
   9
  10 #include <linux/security.h>
  11 #include <linux/module.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/rculist.h>
  14 #include <linux/error-injection.h>
  15
  16 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
  17
  18 #include "trace_dynevent.h"
  19 #include "trace_kprobe_selftest.h"
  20 #include "trace_probe.h"
  21 #include "trace_probe_tmpl.h"
  22
  23 #define KPROBE_EVENT_SYSTEM "kprobes"
  24 #define KRETPROBE_MAXACTIVE_MAX 4096
  25 #define MAX_KPROBE_CMDLINE_SIZE 1024
  26
  27 /* Kprobe early definition from command line */
  28 static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
  29 static bool kprobe_boot_events_enabled __initdata;
  30
  31 static int __init set_kprobe_boot_events(char *str)
  32 {
  33         strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
  34         return 0;
  35 }
  36 __setup("kprobe_event=", set_kprobe_boot_events);
  37
  38 static int trace_kprobe_create(int argc, const char **argv);
  39 static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
  40 static int trace_kprobe_release(struct dyn_event *ev);
  41 static bool trace_kprobe_is_busy(struct dyn_event *ev);
  42 static bool trace_kprobe_match(const char *system, const char *event,
  43                         int argc, const char **argv, struct dyn_event *ev);
  44
  45 static struct dyn_event_operations trace_kprobe_ops = {
  46         .create = trace_kprobe_create,
  47         .show = trace_kprobe_show,
  48         .is_busy = trace_kprobe_is_busy,
  49         .free = trace_kprobe_release,
  50         .match = trace_kprobe_match,
  51 };
  52
  53 /*
  54  * Kprobe event core functions
  55  */
  56 struct trace_kprobe {
  57         struct dyn_event        devent;
  58         struct kretprobe        rp;     /* Use rp.kp for kprobe use */
  59         unsigned long __percpu *nhit;
  60         const char              *symbol;        /* symbol name */
  61         struct trace_probe      tp;
  62 };
  63
  64 static bool is_trace_kprobe(struct dyn_event *ev)
  65 {
  66         return ev->ops == &trace_kprobe_ops;
  67 }
  68
  69 static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
  70 {
  71         return container_of(ev, struct trace_kprobe, devent);
  72 }
  73
  74 /**
  75  * for_each_trace_kprobe - iterate over the trace_kprobe list
  76  * @pos:        the struct trace_kprobe * for each entry
  77  * @dpos:       the struct dyn_event * to use as a loop cursor
  78  */
  79 #define for_each_trace_kprobe(pos, dpos)        \
  80         for_each_dyn_event(dpos)                \
  81                 if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
  82
  83 #define SIZEOF_TRACE_KPROBE(n)                          \
  84         (offsetof(struct trace_kprobe, tp.args) +       \
  85         (sizeof(struct probe_arg) * (n)))
  86
  87 static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
  88 {
  89         return tk->rp.handler != NULL;
  90 }
  91
  92 static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
  93 {
  94         return tk->symbol ? tk->symbol : "unknown";
  95 }
  96
  97 static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
  98 {
  99         return tk->rp.kp.offset;
 100 }
 101
 102 static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
 103 {
 104         return !!(kprobe_gone(&tk->rp.kp));
 105 }
 106
 107 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
 108                                                  struct module *mod)
 109 {
 110         int len = strlen(mod->name);
 111         const char *name = trace_kprobe_symbol(tk);
 112         return strncmp(mod->name, name, len) == 0 && name[len] == ':';
 113 }
 114
 115 static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 116 {
 117         char *p;
 118         bool ret;
 119
 120         if (!tk->symbol)
 121                 return false;
 122         p = strchr(tk->symbol, ':');
 123         if (!p)
 124                 return true;
 125         *p = '\0';
 126         mutex_lock(&module_mutex);
 127         ret = !!find_module(tk->symbol);
 128         mutex_unlock(&module_mutex);
 129         *p = ':';
 130
 131         return ret;
 132 }
 133
 134 static bool trace_kprobe_is_busy(struct dyn_event *ev)
 135 {
 136         struct trace_kprobe *tk = to_trace_kprobe(ev);
 137
 138         return trace_probe_is_enabled(&tk->tp);
 139 }
 140
 141 static bool trace_kprobe_match_command_head(struct trace_kprobe *tk,
 142                                             int argc, const char **argv)
 143 {
 144         char buf[MAX_ARGSTR_LEN + 1];
 145
 146         if (!argc)
 147                 return true;
 148
 149         if (!tk->symbol)
 150                 snprintf(buf, sizeof(buf), "0x%p", tk->rp.kp.addr);
 151         else if (tk->rp.kp.offset)
 152                 snprintf(buf, sizeof(buf), "%s+%u",
 153                          trace_kprobe_symbol(tk), tk->rp.kp.offset);
 154         else
 155                 snprintf(buf, sizeof(buf), "%s", trace_kprobe_symbol(tk));
 156         if (strcmp(buf, argv[0]))
 157                 return false;
 158         argc--; argv++;
 159
 160         return trace_probe_match_command_args(&tk->tp, argc, argv);
 161 }
 162
 163 static bool trace_kprobe_match(const char *system, const char *event,
 164                         int argc, const char **argv, struct dyn_event *ev)
 165 {
 166         struct trace_kprobe *tk = to_trace_kprobe(ev);
 167
 168         return strcmp(trace_probe_name(&tk->tp), event) == 0 &&
 169             (!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
 170             trace_kprobe_match_command_head(tk, argc, argv);
 171 }
 172
 173 static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
 174 {
 175         unsigned long nhit = 0;
 176         int cpu;
 177
 178         for_each_possible_cpu(cpu)
 179                 nhit += *per_cpu_ptr(tk->nhit, cpu);
 180
 181         return nhit;
 182 }
 183
 184 static nokprobe_inline bool trace_kprobe_is_registered(struct trace_kprobe *tk)
 185 {
 186         return !(list_empty(&tk->rp.kp.list) &&
 187                  hlist_unhashed(&tk->rp.kp.hlist));
 188 }
 189
 190 /* Return 0 if it fails to find the symbol address */
 191 static nokprobe_inline
 192 unsigned long trace_kprobe_address(struct trace_kprobe *tk)
 193 {
 194         unsigned long addr;
 195
 196         if (tk->symbol) {
 197                 addr = (unsigned long)
 198                         kallsyms_lookup_name(trace_kprobe_symbol(tk));
 199                 if (addr)
 200                         addr += tk->rp.kp.offset;
 201         } else {
 202                 addr = (unsigned long)tk->rp.kp.addr;
 203         }
 204         return addr;
 205 }
 206
 207 static nokprobe_inline struct trace_kprobe *
 208 trace_kprobe_primary_from_call(struct trace_event_call *call)
 209 {
 210         struct trace_probe *tp;
 211
 212         tp = trace_probe_primary_from_call(call);
 213         if (WARN_ON_ONCE(!tp))
 214                 return NULL;
 215
 216         return container_of(tp, struct trace_kprobe, tp);
 217 }
 218
 219 bool trace_kprobe_on_func_entry(struct trace_event_call *call)
 220 {
 221         struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
 222
 223         return tk ? (kprobe_on_func_entry(tk->rp.kp.addr,
 224                         tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
 225                         tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
 226 }
 227
 228 bool trace_kprobe_error_injectable(struct trace_event_call *call)
 229 {
 230         struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
 231
 232         return tk ? within_error_injection_list(trace_kprobe_address(tk)) :
 233                false;
 234 }
 235
 236 static int register_kprobe_event(struct trace_kprobe *tk);
 237 static int unregister_kprobe_event(struct trace_kprobe *tk);
 238
 239 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 240 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 241                                 struct pt_regs *regs);
 242
 243 static void free_trace_kprobe(struct trace_kprobe *tk)
 244 {
 245         if (tk) {
 246                 trace_probe_cleanup(&tk->tp);
 247                 kfree(tk->symbol);
 248                 free_percpu(tk->nhit);
 249                 kfree(tk);
 250         }
 251 }
 252
 253 /*
 254  * Allocate new trace_probe and initialize it (including kprobes).
 255  */
 256 static struct trace_kprobe *alloc_trace_kprobe(const char *group,
 257                                              const char *event,
 258                                              void *addr,
 259                                              const char *symbol,
 260                                              unsigned long offs,
 261                                              int maxactive,
 262                                              int nargs, bool is_return)
 263 {
 264         struct trace_kprobe *tk;
 265         int ret = -ENOMEM;
 266
 267         tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
 268         if (!tk)
 269                 return ERR_PTR(ret);
 270
 271         tk->nhit = alloc_percpu(unsigned long);
 272         if (!tk->nhit)
 273                 goto error;
 274
 275         if (symbol) {
 276                 tk->symbol = kstrdup(symbol, GFP_KERNEL);
 277                 if (!tk->symbol)
 278                         goto error;
 279                 tk->rp.kp.symbol_name = tk->symbol;
 280                 tk->rp.kp.offset = offs;
 281         } else
 282                 tk->rp.kp.addr = addr;
 283
 284         if (is_return)
 285                 tk->rp.handler = kretprobe_dispatcher;
 286         else
 287                 tk->rp.kp.pre_handler = kprobe_dispatcher;
 288
 289         tk->rp.maxactive = maxactive;
 290         INIT_HLIST_NODE(&tk->rp.kp.hlist);
 291         INIT_LIST_HEAD(&tk->rp.kp.list);
 292
 293         ret = trace_probe_init(&tk->tp, event, group, false);
 294         if (ret < 0)
 295                 goto error;
 296
 297         dyn_event_init(&tk->devent, &trace_kprobe_ops);
 298         return tk;
 299 error:
 300         free_trace_kprobe(tk);
 301         return ERR_PTR(ret);
 302 }
 303
 304 static struct trace_kprobe *find_trace_kprobe(const char *event,
 305                                               const char *group)
 306 {
 307         struct dyn_event *pos;
 308         struct trace_kprobe *tk;
 309
 310         for_each_trace_kprobe(tk, pos)
 311                 if (strcmp(trace_probe_name(&tk->tp), event) == 0 &&
 312                     strcmp(trace_probe_group_name(&tk->tp), group) == 0)
 313                         return tk;
 314         return NULL;
 315 }
 316
 317 static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
 318 {
 319         int ret = 0;
 320
 321         if (trace_kprobe_is_registered(tk) && !trace_kprobe_has_gone(tk)) {
 322                 if (trace_kprobe_is_return(tk))
 323                         ret = enable_kretprobe(&tk->rp);
 324                 else
 325                         ret = enable_kprobe(&tk->rp.kp);
 326         }
 327
 328         return ret;
 329 }
 330
 331 static void __disable_trace_kprobe(struct trace_probe *tp)
 332 {
 333         struct trace_probe *pos;
 334         struct trace_kprobe *tk;
 335
 336         list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
 337                 tk = container_of(pos, struct trace_kprobe, tp);
 338                 if (!trace_kprobe_is_registered(tk))
 339                         continue;
 340                 if (trace_kprobe_is_return(tk))
 341                         disable_kretprobe(&tk->rp);
 342                 else
 343                         disable_kprobe(&tk->rp.kp);
 344         }
 345 }
 346
 347 /*
 348  * Enable trace_probe
 349  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
 350  */
 351 static int enable_trace_kprobe(struct trace_event_call *call,
 352                                 struct trace_event_file *file)
 353 {
 354         struct trace_probe *pos, *tp;
 355         struct trace_kprobe *tk;
 356         bool enabled;
 357         int ret = 0;
 358
 359         tp = trace_probe_primary_from_call(call);
 360         if (WARN_ON_ONCE(!tp))
 361                 return -ENODEV;
 362         enabled = trace_probe_is_enabled(tp);
 363
 364         /* This also changes "enabled" state */
 365         if (file) {
 366                 ret = trace_probe_add_file(tp, file);
 367                 if (ret)
 368                         return ret;
 369         } else
 370                 trace_probe_set_flag(tp, TP_FLAG_PROFILE);
 371
 372         if (enabled)
 373                 return 0;
 374
 375         list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
 376                 tk = container_of(pos, struct trace_kprobe, tp);
 377                 if (trace_kprobe_has_gone(tk))
 378                         continue;
 379                 ret = __enable_trace_kprobe(tk);
 380                 if (ret)
 381                         break;
 382                 enabled = true;
 383         }
 384
 385         if (ret) {
 386                 /* Failed to enable one of them. Roll back all */
 387                 if (enabled)
 388                         __disable_trace_kprobe(tp);
 389                 if (file)
 390                         trace_probe_remove_file(tp, file);
 391                 else
 392                         trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
 393         }
 394
 395         return ret;
 396 }
 397
 398 /*
 399  * Disable trace_probe
 400  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
 401  */
 402 static int disable_trace_kprobe(struct trace_event_call *call,
 403                                 struct trace_event_file *file)
 404 {
 405         struct trace_probe *tp;
 406
 407         tp = trace_probe_primary_from_call(call);
 408         if (WARN_ON_ONCE(!tp))
 409                 return -ENODEV;
 410
 411         if (file) {
 412                 if (!trace_probe_get_file_link(tp, file))
 413                         return -ENOENT;
 414                 if (!trace_probe_has_single_file(tp))
 415                         goto out;
 416                 trace_probe_clear_flag(tp, TP_FLAG_TRACE);
 417         } else
 418                 trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
 419
 420         if (!trace_probe_is_enabled(tp))
 421                 __disable_trace_kprobe(tp);
 422
 423  out:
 424         if (file)
 425                 /*
 426                  * Synchronization is done in below function. For perf event,
 427                  * file == NULL and perf_trace_event_unreg() calls
 428                  * tracepoint_synchronize_unregister() to ensure synchronize
 429                  * event. We don't need to care about it.
 430                  */
 431                 trace_probe_remove_file(tp, file);
 432
 433         return 1;
 434 }
 435
 436 #if defined(CONFIG_DYNAMIC_FTRACE) && \
 437         !defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
 438 static bool __within_notrace_func(unsigned long addr)
 439 {
 440         unsigned long offset, size;
 441
 442         if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))
 443                 return false;
 444
 445         /* Get the entry address of the target function */
 446         addr -= offset;
 447
 448         /*
 449          * Since ftrace_location_range() does inclusive range check, we need
 450          * to subtract 1 byte from the end address.
 451          */
 452         return !ftrace_location_range(addr, addr + size - 1);
 453 }
 454
 455 static bool within_notrace_func(struct trace_kprobe *tk)
 456 {
 457         unsigned long addr = trace_kprobe_address(tk);
 458         char symname[KSYM_NAME_LEN], *p;
 459
 460         if (!__within_notrace_func(addr))
 461                 return false;
 462
 463         /* Check if the address is on a suffixed-symbol */
 464         if (!lookup_symbol_name(addr, symname)) {
 465                 p = strchr(symname, '.');
 466                 if (!p)
 467                         return true;
 468                 *p = '\0';
 469                 addr = (unsigned long)kprobe_lookup_name(symname, 0);
 470                 if (addr)
 471                         return __within_notrace_func(addr);
 472         }
 473
 474         return true;
 475 }
 476 #else
 477 #define within_notrace_func(tk) (false)
 478 #endif
 479
 480 /* Internal register function - just handle k*probes and flags */
 481 static int __register_trace_kprobe(struct trace_kprobe *tk)
 482 {
 483         int i, ret;
 484
 485         ret = security_locked_down(LOCKDOWN_KPROBES);
 486         if (ret)
 487                 return ret;
 488
 489         if (trace_kprobe_is_registered(tk))
 490                 return -EINVAL;
 491
 492         if (within_notrace_func(tk)) {
 493                 pr_warn("Could not probe notrace function %s\n",
 494                         trace_kprobe_symbol(tk));
 495                 return -EINVAL;
 496         }
 497
 498         for (i = 0; i < tk->tp.nr_args; i++) {
 499                 ret = traceprobe_update_arg(&tk->tp.args[i]);
 500                 if (ret)
 501                         return ret;
 502         }
 503
 504         /* Set/clear disabled flag according to tp->flag */
 505         if (trace_probe_is_enabled(&tk->tp))
 506                 tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
 507         else
 508                 tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
 509
 510         if (trace_kprobe_is_return(tk))
 511                 ret = register_kretprobe(&tk->rp);
 512         else
 513                 ret = register_kprobe(&tk->rp.kp);
 514
 515         return ret;
 516 }
 517
 518 /* Internal unregister function - just handle k*probes and flags */
 519 static void __unregister_trace_kprobe(struct trace_kprobe *tk)
 520 {
 521         if (trace_kprobe_is_registered(tk)) {
 522                 if (trace_kprobe_is_return(tk))
 523                         unregister_kretprobe(&tk->rp);
 524                 else
 525                         unregister_kprobe(&tk->rp.kp);
 526                 /* Cleanup kprobe for reuse and mark it unregistered */
 527                 INIT_HLIST_NODE(&tk->rp.kp.hlist);
 528                 INIT_LIST_HEAD(&tk->rp.kp.list);
 529                 if (tk->rp.kp.symbol_name)
 530                         tk->rp.kp.addr = NULL;
 531         }
 532 }
 533
 534 /* Unregister a trace_probe and probe_event */
 535 static int unregister_trace_kprobe(struct trace_kprobe *tk)
 536 {
 537         /* If other probes are on the event, just unregister kprobe */
 538         if (trace_probe_has_sibling(&tk->tp))
 539                 goto unreg;
 540
 541         /* Enabled event can not be unregistered */
 542         if (trace_probe_is_enabled(&tk->tp))
 543                 return -EBUSY;
 544
 545         /* Will fail if probe is being used by ftrace or perf */
 546         if (unregister_kprobe_event(tk))
 547                 return -EBUSY;
 548
 549 unreg:
 550         __unregister_trace_kprobe(tk);
 551         dyn_event_remove(&tk->devent);
 552         trace_probe_unlink(&tk->tp);
 553
 554         return 0;
 555 }
 556
 557 static bool trace_kprobe_has_same_kprobe(struct trace_kprobe *orig,
 558                                          struct trace_kprobe *comp)
 559 {
 560         struct trace_probe_event *tpe = orig->tp.event;
 561         struct trace_probe *pos;
 562         int i;
 563
 564         list_for_each_entry(pos, &tpe->probes, list) {
 565                 orig = container_of(pos, struct trace_kprobe, tp);
 566                 if (strcmp(trace_kprobe_symbol(orig),
 567                            trace_kprobe_symbol(comp)) ||
 568                     trace_kprobe_offset(orig) != trace_kprobe_offset(comp))
 569                         continue;
 570
 571                 /*
 572                  * trace_probe_compare_arg_type() ensured that nr_args and
 573                  * each argument name and type are same. Let's compare comm.
 574                  */
 575                 for (i = 0; i < orig->tp.nr_args; i++) {
 576                         if (strcmp(orig->tp.args[i].comm,
 577                                    comp->tp.args[i].comm))
 578                                 break;
 579                 }
 580
 581                 if (i == orig->tp.nr_args)
 582                         return true;
 583         }
 584
 585         return false;
 586 }
 587
 588 static int append_trace_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to)
 589 {
 590         int ret;
 591
 592         ret = trace_probe_compare_arg_type(&tk->tp, &to->tp);
 593         if (ret) {
 594                 /* Note that argument starts index = 2 */
 595                 trace_probe_log_set_index(ret + 1);
 596                 trace_probe_log_err(0, DIFF_ARG_TYPE);
 597                 return -EEXIST;
 598         }
 599         if (trace_kprobe_has_same_kprobe(to, tk)) {
 600                 trace_probe_log_set_index(0);
 601                 trace_probe_log_err(0, SAME_PROBE);
 602                 return -EEXIST;
 603         }
 604
 605         /* Append to existing event */
 606         ret = trace_probe_append(&tk->tp, &to->tp);
 607         if (ret)
 608                 return ret;
 609
 610         /* Register k*probe */
 611         ret = __register_trace_kprobe(tk);
 612         if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
 613                 pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
 614                 ret = 0;
 615         }
 616
 617         if (ret)
 618                 trace_probe_unlink(&tk->tp);
 619         else
 620                 dyn_event_add(&tk->devent);
 621
 622         return ret;
 623 }
 624
 625 /* Register a trace_probe and probe_event */
 626 static int register_trace_kprobe(struct trace_kprobe *tk)
 627 {
 628         struct trace_kprobe *old_tk;
 629         int ret;
 630
 631         mutex_lock(&event_mutex);
 632
 633         old_tk = find_trace_kprobe(trace_probe_name(&tk->tp),
 634                                    trace_probe_group_name(&tk->tp));
 635         if (old_tk) {
 636                 if (trace_kprobe_is_return(tk) != trace_kprobe_is_return(old_tk)) {
 637                         trace_probe_log_set_index(0);
 638                         trace_probe_log_err(0, DIFF_PROBE_TYPE);
 639                         ret = -EEXIST;
 640                 } else {
 641                         ret = append_trace_kprobe(tk, old_tk);
 642                 }
 643                 goto end;
 644         }
 645
 646         /* Register new event */
 647         ret = register_kprobe_event(tk);
 648         if (ret) {
 649                 if (ret == -EEXIST) {
 650                         trace_probe_log_set_index(0);
 651                         trace_probe_log_err(0, EVENT_EXIST);
 652                 } else
 653                         pr_warn("Failed to register probe event(%d)\n", ret);
 654                 goto end;
 655         }
 656
 657         /* Register k*probe */
 658         ret = __register_trace_kprobe(tk);
 659         if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
 660                 pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
 661                 ret = 0;
 662         }
 663
 664         if (ret < 0)
 665                 unregister_kprobe_event(tk);
 666         else
 667                 dyn_event_add(&tk->devent);
 668
 669 end:
 670         mutex_unlock(&event_mutex);
 671         return ret;
 672 }
 673
 674 /* Module notifier call back, checking event on the module */
 675 static int trace_kprobe_module_callback(struct notifier_block *nb,
 676                                        unsigned long val, void *data)
 677 {
 678         struct module *mod = data;
 679         struct dyn_event *pos;
 680         struct trace_kprobe *tk;
 681         int ret;
 682
 683         if (val != MODULE_STATE_COMING)
 684                 return NOTIFY_DONE;
 685
 686         /* Update probes on coming module */
 687         mutex_lock(&event_mutex);
 688         for_each_trace_kprobe(tk, pos) {
 689                 if (trace_kprobe_within_module(tk, mod)) {
 690                         /* Don't need to check busy - this should have gone. */
 691                         __unregister_trace_kprobe(tk);
 692                         ret = __register_trace_kprobe(tk);
 693                         if (ret)
 694                                 pr_warn("Failed to re-register probe %s on %s: %d\n",
 695                                         trace_probe_name(&tk->tp),
 696                                         mod->name, ret);
 697                 }
 698         }
 699         mutex_unlock(&event_mutex);
 700
 701         return NOTIFY_DONE;
 702 }
 703
 704 static struct notifier_block trace_kprobe_module_nb = {
 705         .notifier_call = trace_kprobe_module_callback,
 706         .priority = 1   /* Invoked after kprobe module callback */
 707 };
 708
 709 /* Convert certain expected symbols into '_' when generating event names */
 710 static inline void sanitize_event_name(char *name)
 711 {
 712         while (*name++ != '\0')
 713                 if (*name == ':' || *name == '.')
 714                         *name = '_';
 715 }
 716
 717 static int trace_kprobe_create(int argc, const char *argv[])
 718 {
 719         /*
 720          * Argument syntax:
 721          *  - Add kprobe:
 722          *      p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
 723          *  - Add kretprobe:
 724          *      r[MAXACTIVE][:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
 725          * Fetch args:
 726          *  $retval     : fetch return value
 727          *  $stack      : fetch stack address
 728          *  $stackN     : fetch Nth of stack (N:0-)
 729          *  $comm       : fetch current task comm
 730          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
 731          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 732          *  %REG        : fetch register REG
 733          * Dereferencing memory fetch:
 734          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
 735          * Alias name of args:
 736          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
 737          * Type of args:
 738          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 739          */
 740         struct trace_kprobe *tk = NULL;
 741         int i, len, ret = 0;
 742         bool is_return = false;
 743         char *symbol = NULL, *tmp = NULL;
 744         const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
 745         int maxactive = 0;
 746         long offset = 0;
 747         void *addr = NULL;
 748         char buf[MAX_EVENT_NAME_LEN];
 749         unsigned int flags = TPARG_FL_KERNEL;
 750
 751         switch (argv[0][0]) {
 752         case 'r':
 753                 is_return = true;
 754                 flags |= TPARG_FL_RETURN;
 755                 break;
 756         case 'p':
 757                 break;
 758         default:
 759                 return -ECANCELED;
 760         }
 761         if (argc < 2)
 762                 return -ECANCELED;
 763
 764         trace_probe_log_init("trace_kprobe", argc, argv);
 765
 766         event = strchr(&argv[0][1], ':');
 767         if (event)
 768                 event++;
 769
 770         if (isdigit(argv[0][1])) {
 771                 if (!is_return) {
 772                         trace_probe_log_err(1, MAXACT_NO_KPROBE);
 773                         goto parse_error;
 774                 }
 775                 if (event)
 776                         len = event - &argv[0][1] - 1;
 777                 else
 778                         len = strlen(&argv[0][1]);
 779                 if (len > MAX_EVENT_NAME_LEN - 1) {
 780                         trace_probe_log_err(1, BAD_MAXACT);
 781                         goto parse_error;
 782                 }
 783                 memcpy(buf, &argv[0][1], len);
 784                 buf[len] = '\0';
 785                 ret = kstrtouint(buf, 0, &maxactive);
 786                 if (ret || !maxactive) {
 787                         trace_probe_log_err(1, BAD_MAXACT);
 788                         goto parse_error;
 789                 }
 790                 /* kretprobes instances are iterated over via a list. The
 791                  * maximum should stay reasonable.
 792                  */
 793                 if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
 794                         trace_probe_log_err(1, MAXACT_TOO_BIG);
 795                         goto parse_error;
 796                 }
 797         }
 798
 799         /* try to parse an address. if that fails, try to read the
 800          * input as a symbol. */
 801         if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
 802                 trace_probe_log_set_index(1);
 803                 /* Check whether uprobe event specified */
 804                 if (strchr(argv[1], '/') && strchr(argv[1], ':')) {
 805                         ret = -ECANCELED;
 806                         goto error;
 807                 }
 808                 /* a symbol specified */
 809                 symbol = kstrdup(argv[1], GFP_KERNEL);
 810                 if (!symbol)
 811                         return -ENOMEM;
 812                 /* TODO: support .init module functions */
 813                 ret = traceprobe_split_symbol_offset(symbol, &offset);
 814                 if (ret || offset < 0 || offset > UINT_MAX) {
 815                         trace_probe_log_err(0, BAD_PROBE_ADDR);
 816                         goto parse_error;
 817                 }
 818                 ret = kprobe_on_func_entry(NULL, symbol, offset);
 819                 if (ret == 0)
 820                         flags |= TPARG_FL_FENTRY;
 821                 /* Defer the ENOENT case until register kprobe */
 822                 if (ret == -EINVAL && is_return) {
 823                         trace_probe_log_err(0, BAD_RETPROBE);
 824                         goto parse_error;
 825                 }
 826         }
 827
 828         trace_probe_log_set_index(0);
 829         if (event) {
 830                 ret = traceprobe_parse_event_name(&event, &group, buf,
 831                                                   event - argv[0]);
 832                 if (ret)
 833                         goto parse_error;
 834         } else {
 835                 /* Make a new event name */
 836                 if (symbol)
 837                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
 838                                  is_return ? 'r' : 'p', symbol, offset);
 839                 else
 840                         snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
 841                                  is_return ? 'r' : 'p', addr);
 842                 sanitize_event_name(buf);
 843                 event = buf;
 844         }
 845
 846         /* setup a probe */
 847         tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
 848                                argc - 2, is_return);
 849         if (IS_ERR(tk)) {
 850                 ret = PTR_ERR(tk);
 851                 /* This must return -ENOMEM, else there is a bug */
 852                 WARN_ON_ONCE(ret != -ENOMEM);
 853                 goto out;       /* We know tk is not allocated */
 854         }
 855         argc -= 2; argv += 2;
 856
 857         /* parse arguments */
 858         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
 859                 tmp = kstrdup(argv[i], GFP_KERNEL);
 860                 if (!tmp) {
 861                         ret = -ENOMEM;
 862                         goto error;
 863                 }
 864
 865                 trace_probe_log_set_index(i + 2);
 866                 ret = traceprobe_parse_probe_arg(&tk->tp, i, tmp, flags);
 867                 kfree(tmp);
 868                 if (ret)
 869                         goto error;     /* This can be -ENOMEM */
 870         }
 871
 872         ret = traceprobe_set_print_fmt(&tk->tp, is_return);
 873         if (ret < 0)
 874                 goto error;
 875
 876         ret = register_trace_kprobe(tk);
 877         if (ret) {
 878                 trace_probe_log_set_index(1);
 879                 if (ret == -EILSEQ)
 880                         trace_probe_log_err(0, BAD_INSN_BNDRY);
 881                 else if (ret == -ENOENT)
 882                         trace_probe_log_err(0, BAD_PROBE_ADDR);
 883                 else if (ret != -ENOMEM && ret != -EEXIST)
 884                         trace_probe_log_err(0, FAIL_REG_PROBE);
 885                 goto error;
 886         }
 887
 888 out:
 889         trace_probe_log_clear();
 890         kfree(symbol);
 891         return ret;
 892
 893 parse_error:
 894         ret = -EINVAL;
 895 error:
 896         free_trace_kprobe(tk);
 897         goto out;
 898 }
 899
 900 static int create_or_delete_trace_kprobe(int argc, char **argv)
 901 {
 902         int ret;
 903
 904         if (argv[0][0] == '-')
 905                 return dyn_event_release(argc, argv, &trace_kprobe_ops);
 906
 907         ret = trace_kprobe_create(argc, (const char **)argv);
 908         return ret == -ECANCELED ? -EINVAL : ret;
 909 }
 910
 911 static int trace_kprobe_release(struct dyn_event *ev)
 912 {
 913         struct trace_kprobe *tk = to_trace_kprobe(ev);
 914         int ret = unregister_trace_kprobe(tk);
 915
 916         if (!ret)
 917                 free_trace_kprobe(tk);
 918         return ret;
 919 }
 920
 921 static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
 922 {
 923         struct trace_kprobe *tk = to_trace_kprobe(ev);
 924         int i;
 925
 926         seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
 927         if (trace_kprobe_is_return(tk) && tk->rp.maxactive)
 928                 seq_printf(m, "%d", tk->rp.maxactive);
 929         seq_printf(m, ":%s/%s", trace_probe_group_name(&tk->tp),
 930                                 trace_probe_name(&tk->tp));
 931
 932         if (!tk->symbol)
 933                 seq_printf(m, " 0x%p", tk->rp.kp.addr);
 934         else if (tk->rp.kp.offset)
 935                 seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
 936                            tk->rp.kp.offset);
 937         else
 938                 seq_printf(m, " %s", trace_kprobe_symbol(tk));
 939
 940         for (i = 0; i < tk->tp.nr_args; i++)
 941                 seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
 942         seq_putc(m, '\n');
 943
 944         return 0;
 945 }
 946
 947 static int probes_seq_show(struct seq_file *m, void *v)
 948 {
 949         struct dyn_event *ev = v;
 950
 951         if (!is_trace_kprobe(ev))
 952                 return 0;
 953
 954         return trace_kprobe_show(m, ev);
 955 }
 956
 957 static const struct seq_operations probes_seq_op = {
 958         .start  = dyn_event_seq_start,
 959         .next   = dyn_event_seq_next,
 960         .stop   = dyn_event_seq_stop,
 961         .show   = probes_seq_show
 962 };
 963
 964 static int probes_open(struct inode *inode, struct file *file)
 965 {
 966         int ret;
 967
 968         ret = security_locked_down(LOCKDOWN_TRACEFS);
 969         if (ret)
 970                 return ret;
 971
 972         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 973                 ret = dyn_events_release_all(&trace_kprobe_ops);
 974                 if (ret < 0)
 975                         return ret;
 976         }
 977
 978         return seq_open(file, &probes_seq_op);
 979 }
 980
 981 static ssize_t probes_write(struct file *file, const char __user *buffer,
 982                             size_t count, loff_t *ppos)
 983 {
 984         return trace_parse_run_command(file, buffer, count, ppos,
 985                                        create_or_delete_trace_kprobe);
 986 }
 987
 988 static const struct file_operations kprobe_events_ops = {
 989         .owner          = THIS_MODULE,
 990         .open           = probes_open,
 991         .read           = seq_read,
 992         .llseek         = seq_lseek,
 993         .release        = seq_release,
 994         .write          = probes_write,
 995 };
 996
 997 /* Probes profiling interfaces */
 998 static int probes_profile_seq_show(struct seq_file *m, void *v)
 999 {
1000         struct dyn_event *ev = v;
1001         struct trace_kprobe *tk;
1002         unsigned long nmissed;
1003
1004         if (!is_trace_kprobe(ev))
1005                 return 0;
1006
1007         tk = to_trace_kprobe(ev);
1008         nmissed = trace_kprobe_is_return(tk) ?
1009                 tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
1010         seq_printf(m, "  %-44s %15lu %15lu\n",
1011                    trace_probe_name(&tk->tp),
1012                    trace_kprobe_nhit(tk),
1013                    nmissed);
1014
1015         return 0;
1016 }
1017
1018 static const struct seq_operations profile_seq_op = {
1019         .start  = dyn_event_seq_start,
1020         .next   = dyn_event_seq_next,
1021         .stop   = dyn_event_seq_stop,
1022         .show   = probes_profile_seq_show
1023 };
1024
1025 static int profile_open(struct inode *inode, struct file *file)
1026 {
1027         int ret;
1028
1029         ret = security_locked_down(LOCKDOWN_TRACEFS);
1030         if (ret)
1031                 return ret;
1032
1033         return seq_open(file, &profile_seq_op);
1034 }
1035
1036 static const struct file_operations kprobe_profile_ops = {
1037         .owner          = THIS_MODULE,
1038         .open           = profile_open,
1039         .read           = seq_read,
1040         .llseek         = seq_lseek,
1041         .release        = seq_release,
1042 };
1043
1044 /* Kprobe specific fetch functions */
1045
1046 /* Return the length of string -- including null terminal byte */
1047 static nokprobe_inline int
1048 fetch_store_strlen(unsigned long addr)
1049 {
1050         int ret, len = 0;
1051         u8 c;
1052
1053         do {
1054                 ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
1055                 len++;
1056         } while (c && ret == 0 && len < MAX_STRING_SIZE);
1057
1058         return (ret < 0) ? ret : len;
1059 }
1060
1061 /* Return the length of string -- including null terminal byte */
1062 static nokprobe_inline int
1063 fetch_store_strlen_user(unsigned long addr)
1064 {
1065         const void __user *uaddr =  (__force const void __user *)addr;
1066
1067         return strnlen_unsafe_user(uaddr, MAX_STRING_SIZE);
1068 }
1069
1070 /*
1071  * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
1072  * length and relative data location.
1073  */
1074 static nokprobe_inline int
1075 fetch_store_string(unsigned long addr, void *dest, void *base)
1076 {
1077         int maxlen = get_loc_len(*(u32 *)dest);
1078         void *__dest;
1079         long ret;
1080
1081         if (unlikely(!maxlen))
1082                 return -ENOMEM;
1083
1084         __dest = get_loc_data(dest, base);
1085
1086         /*
1087          * Try to get string again, since the string can be changed while
1088          * probing.
1089          */
1090         ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen);
1091         if (ret >= 0)
1092                 *(u32 *)dest = make_data_loc(ret, __dest - base);
1093
1094         return ret;
1095 }
1096
1097 /*
1098  * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
1099  * with max length and relative data location.
1100  */
1101 static nokprobe_inline int
1102 fetch_store_string_user(unsigned long addr, void *dest, void *base)
1103 {
1104         const void __user *uaddr =  (__force const void __user *)addr;
1105         int maxlen = get_loc_len(*(u32 *)dest);
1106         void *__dest;
1107         long ret;
1108
1109         if (unlikely(!maxlen))
1110                 return -ENOMEM;
1111
1112         __dest = get_loc_data(dest, base);
1113
1114         ret = strncpy_from_unsafe_user(__dest, uaddr, maxlen);
1115         if (ret >= 0)
1116                 *(u32 *)dest = make_data_loc(ret, __dest - base);
1117
1118         return ret;
1119 }
1120
1121 static nokprobe_inline int
1122 probe_mem_read(void *dest, void *src, size_t size)
1123 {
1124         return probe_kernel_read(dest, src, size);
1125 }
1126
1127 static nokprobe_inline int
1128 probe_mem_read_user(void *dest, void *src, size_t size)
1129 {
1130         const void __user *uaddr =  (__force const void __user *)src;
1131
1132         return probe_user_read(dest, uaddr, size);
1133 }
1134
1135 /* Note that we don't verify it, since the code does not come from user space */
1136 static int
1137 process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
1138                    void *base)
1139 {
1140         struct pt_regs *regs = rec;
1141         unsigned long val;
1142
1143 retry:
1144         /* 1st stage: get value from context */
1145         switch (code->op) {
1146         case FETCH_OP_REG:
1147                 val = regs_get_register(regs, code->param);
1148                 break;
1149         case FETCH_OP_STACK:
1150                 val = regs_get_kernel_stack_nth(regs, code->param);
1151                 break;
1152         case FETCH_OP_STACKP:
1153                 val = kernel_stack_pointer(regs);
1154                 break;
1155         case FETCH_OP_RETVAL:
1156                 val = regs_return_value(regs);
1157                 break;
1158         case FETCH_OP_IMM:
1159                 val = code->immediate;
1160                 break;
1161         case FETCH_OP_COMM:
1162                 val = (unsigned long)current->comm;
1163                 break;
1164         case FETCH_OP_DATA:
1165                 val = (unsigned long)code->data;
1166                 break;
1167 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
1168         case FETCH_OP_ARG:
1169                 val = regs_get_kernel_argument(regs, code->param);
1170                 break;
1171 #endif
1172         case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
1173                 code++;
1174                 goto retry;
1175         default:
1176                 return -EILSEQ;
1177         }
1178         code++;
1179
1180         return process_fetch_insn_bottom(code, val, dest, base);
1181 }
1182 NOKPROBE_SYMBOL(process_fetch_insn)
1183
1184 /* Kprobe handler */
1185 static nokprobe_inline void
1186 __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
1187                     struct trace_event_file *trace_file)
1188 {
1189         struct kprobe_trace_entry_head *entry;
1190         struct ring_buffer_event *event;
1191         struct ring_buffer *buffer;
1192         int size, dsize, pc;
1193         unsigned long irq_flags;
1194         struct trace_event_call *call = trace_probe_event_call(&tk->tp);
1195
1196         WARN_ON(call != trace_file->event_call);
1197
1198         if (trace_trigger_soft_disabled(trace_file))
1199                 return;
1200
1201         local_save_flags(irq_flags);
1202         pc = preempt_count();
1203
1204         dsize = __get_data_size(&tk->tp, regs);
1205         size = sizeof(*entry) + tk->tp.size + dsize;
1206
1207         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1208                                                 call->event.type,
1209                                                 size, irq_flags, pc);
1210         if (!event)
1211                 return;
1212
1213         entry = ring_buffer_event_data(event);
1214         entry->ip = (unsigned long)tk->rp.kp.addr;
1215         store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
1216
1217         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1218                                          entry, irq_flags, pc, regs);
1219 }
1220
1221 static void
1222 kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
1223 {
1224         struct event_file_link *link;
1225
1226         trace_probe_for_each_link_rcu(link, &tk->tp)
1227                 __kprobe_trace_func(tk, regs, link->file);
1228 }
1229 NOKPROBE_SYMBOL(kprobe_trace_func);
1230
1231 /* Kretprobe handler */
1232 static nokprobe_inline void
1233 __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1234                        struct pt_regs *regs,
1235                        struct trace_event_file *trace_file)
1236 {
1237         struct kretprobe_trace_entry_head *entry;
1238         struct ring_buffer_event *event;
1239         struct ring_buffer *buffer;
1240         int size, pc, dsize;
1241         unsigned long irq_flags;
1242         struct trace_event_call *call = trace_probe_event_call(&tk->tp);
1243
1244         WARN_ON(call != trace_file->event_call);
1245
1246         if (trace_trigger_soft_disabled(trace_file))
1247                 return;
1248
1249         local_save_flags(irq_flags);
1250         pc = preempt_count();
1251
1252         dsize = __get_data_size(&tk->tp, regs);
1253         size = sizeof(*entry) + tk->tp.size + dsize;
1254
1255         event = trace_event_buffer_lock_reserve(&buffer, trace_file,
1256                                                 call->event.type,
1257                                                 size, irq_flags, pc);
1258         if (!event)
1259                 return;
1260
1261         entry = ring_buffer_event_data(event);
1262         entry->func = (unsigned long)tk->rp.kp.addr;
1263         entry->ret_ip = (unsigned long)ri->ret_addr;
1264         store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
1265
1266         event_trigger_unlock_commit_regs(trace_file, buffer, event,
1267                                          entry, irq_flags, pc, regs);
1268 }
1269
1270 static void
1271 kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1272                      struct pt_regs *regs)
1273 {
1274         struct event_file_link *link;
1275
1276         trace_probe_for_each_link_rcu(link, &tk->tp)
1277                 __kretprobe_trace_func(tk, ri, regs, link->file);
1278 }
1279 NOKPROBE_SYMBOL(kretprobe_trace_func);
1280
1281 /* Event entry printers */
1282 static enum print_line_t
1283 print_kprobe_event(struct trace_iterator *iter, int flags,
1284                    struct trace_event *event)
1285 {
1286         struct kprobe_trace_entry_head *field;
1287         struct trace_seq *s = &iter->seq;
1288         struct trace_probe *tp;
1289
1290         field = (struct kprobe_trace_entry_head *)iter->ent;
1291         tp = trace_probe_primary_from_call(
1292                 container_of(event, struct trace_event_call, event));
1293         if (WARN_ON_ONCE(!tp))
1294                 goto out;
1295
1296         trace_seq_printf(s, "%s: (", trace_probe_name(tp));
1297
1298         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
1299                 goto out;
1300
1301         trace_seq_putc(s, ')');
1302
1303         if (print_probe_args(s, tp->args, tp->nr_args,
1304                              (u8 *)&field[1], field) < 0)
1305                 goto out;
1306
1307         trace_seq_putc(s, '\n');
1308  out:
1309         return trace_handle_return(s);
1310 }
1311
1312 static enum print_line_t
1313 print_kretprobe_event(struct trace_iterator *iter, int flags,
1314                       struct trace_event *event)
1315 {
1316         struct kretprobe_trace_entry_head *field;
1317         struct trace_seq *s = &iter->seq;
1318         struct trace_probe *tp;
1319
1320         field = (struct kretprobe_trace_entry_head *)iter->ent;
1321         tp = trace_probe_primary_from_call(
1322                 container_of(event, struct trace_event_call, event));
1323         if (WARN_ON_ONCE(!tp))
1324                 goto out;
1325
1326         trace_seq_printf(s, "%s: (", trace_probe_name(tp));
1327
1328         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
1329                 goto out;
1330
1331         trace_seq_puts(s, " <- ");
1332
1333         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
1334                 goto out;
1335
1336         trace_seq_putc(s, ')');
1337
1338         if (print_probe_args(s, tp->args, tp->nr_args,
1339                              (u8 *)&field[1], field) < 0)
1340                 goto out;
1341
1342         trace_seq_putc(s, '\n');
1343
1344  out:
1345         return trace_handle_return(s);
1346 }
1347
1348
1349 static int kprobe_event_define_fields(struct trace_event_call *event_call)
1350 {
1351         int ret;
1352         struct kprobe_trace_entry_head field;
1353         struct trace_probe *tp;
1354
1355         tp = trace_probe_primary_from_call(event_call);
1356         if (WARN_ON_ONCE(!tp))
1357                 return -ENOENT;
1358
1359         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
1360
1361         return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
1362 }
1363
1364 static int kretprobe_event_define_fields(struct trace_event_call *event_call)
1365 {
1366         int ret;
1367         struct kretprobe_trace_entry_head field;
1368         struct trace_probe *tp;
1369
1370         tp = trace_probe_primary_from_call(event_call);
1371         if (WARN_ON_ONCE(!tp))
1372                 return -ENOENT;
1373
1374         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
1375         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
1376
1377         return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
1378 }
1379
1380 #ifdef CONFIG_PERF_EVENTS
1381
1382 /* Kprobe profile handler */
1383 static int
1384 kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
1385 {
1386         struct trace_event_call *call = trace_probe_event_call(&tk->tp);
1387         struct kprobe_trace_entry_head *entry;
1388         struct hlist_head *head;
1389         int size, __size, dsize;
1390         int rctx;
1391
1392         if (bpf_prog_array_valid(call)) {
1393                 unsigned long orig_ip = instruction_pointer(regs);
1394                 int ret;
1395
1396                 ret = trace_call_bpf(call, regs);
1397
1398                 /*
1399                  * We need to check and see if we modified the pc of the
1400                  * pt_regs, and if so return 1 so that we don't do the
1401                  * single stepping.
1402                  */
1403                 if (orig_ip != instruction_pointer(regs))
1404                         return 1;
1405                 if (!ret)
1406                         return 0;
1407         }
1408
1409         head = this_cpu_ptr(call->perf_events);
1410         if (hlist_empty(head))
1411                 return 0;
1412
1413         dsize = __get_data_size(&tk->tp, regs);
1414         __size = sizeof(*entry) + tk->tp.size + dsize;
1415         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1416         size -= sizeof(u32);
1417
1418         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1419         if (!entry)
1420                 return 0;
1421
1422         entry->ip = (unsigned long)tk->rp.kp.addr;
1423         memset(&entry[1], 0, dsize);
1424         store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
1425         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1426                               head, NULL);
1427         return 0;
1428 }
1429 NOKPROBE_SYMBOL(kprobe_perf_func);
1430
1431 /* Kretprobe profile handler */
1432 static void
1433 kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
1434                     struct pt_regs *regs)
1435 {
1436         struct trace_event_call *call = trace_probe_event_call(&tk->tp);
1437         struct kretprobe_trace_entry_head *entry;
1438         struct hlist_head *head;
1439         int size, __size, dsize;
1440         int rctx;
1441
1442         if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
1443                 return;
1444
1445         head = this_cpu_ptr(call->perf_events);
1446         if (hlist_empty(head))
1447                 return;
1448
1449         dsize = __get_data_size(&tk->tp, regs);
1450         __size = sizeof(*entry) + tk->tp.size + dsize;
1451         size = ALIGN(__size + sizeof(u32), sizeof(u64));
1452         size -= sizeof(u32);
1453
1454         entry = perf_trace_buf_alloc(size, NULL, &rctx);
1455         if (!entry)
1456                 return;
1457
1458         entry->func = (unsigned long)tk->rp.kp.addr;
1459         entry->ret_ip = (unsigned long)ri->ret_addr;
1460         store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
1461         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
1462                               head, NULL);
1463 }
1464 NOKPROBE_SYMBOL(kretprobe_perf_func);
1465
1466 int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
1467                         const char **symbol, u64 *probe_offset,
1468                         u64 *probe_addr, bool perf_type_tracepoint)
1469 {
1470         const char *pevent = trace_event_name(event->tp_event);
1471         const char *group = event->tp_event->class->system;
1472         struct trace_kprobe *tk;
1473
1474         if (perf_type_tracepoint)
1475                 tk = find_trace_kprobe(pevent, group);
1476         else
1477                 tk = trace_kprobe_primary_from_call(event->tp_event);
1478         if (!tk)
1479                 return -EINVAL;
1480
1481         *fd_type = trace_kprobe_is_return(tk) ? BPF_FD_TYPE_KRETPROBE
1482                                               : BPF_FD_TYPE_KPROBE;
1483         if (tk->symbol) {
1484                 *symbol = tk->symbol;
1485                 *probe_offset = tk->rp.kp.offset;
1486                 *probe_addr = 0;
1487         } else {
1488                 *symbol = NULL;
1489                 *probe_offset = 0;
1490                 *probe_addr = (unsigned long)tk->rp.kp.addr;
1491         }
1492         return 0;
1493 }
1494 #endif  /* CONFIG_PERF_EVENTS */
1495
1496 /*
1497  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1498  *
1499  * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
1500  * lockless, but we can't race with this __init function.
1501  */
1502 static int kprobe_register(struct trace_event_call *event,
1503                            enum trace_reg type, void *data)
1504 {
1505         struct trace_event_file *file = data;
1506
1507         switch (type) {
1508         case TRACE_REG_REGISTER:
1509                 return enable_trace_kprobe(event, file);
1510         case TRACE_REG_UNREGISTER:
1511                 return disable_trace_kprobe(event, file);
1512
1513 #ifdef CONFIG_PERF_EVENTS
1514         case TRACE_REG_PERF_REGISTER:
1515                 return enable_trace_kprobe(event, NULL);
1516         case TRACE_REG_PERF_UNREGISTER:
1517                 return disable_trace_kprobe(event, NULL);
1518         case TRACE_REG_PERF_OPEN:
1519         case TRACE_REG_PERF_CLOSE:
1520         case TRACE_REG_PERF_ADD:
1521         case TRACE_REG_PERF_DEL:
1522                 return 0;
1523 #endif
1524         }
1525         return 0;
1526 }
1527
1528 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
1529 {
1530         struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
1531         int ret = 0;
1532
1533         raw_cpu_inc(*tk->nhit);
1534
1535         if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
1536                 kprobe_trace_func(tk, regs);
1537 #ifdef CONFIG_PERF_EVENTS
1538         if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
1539                 ret = kprobe_perf_func(tk, regs);
1540 #endif
1541         return ret;
1542 }
1543 NOKPROBE_SYMBOL(kprobe_dispatcher);
1544
1545 static int
1546 kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
1547 {
1548         struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
1549
1550         raw_cpu_inc(*tk->nhit);
1551
1552         if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
1553                 kretprobe_trace_func(tk, ri, regs);
1554 #ifdef CONFIG_PERF_EVENTS
1555         if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
1556                 kretprobe_perf_func(tk, ri, regs);
1557 #endif
1558         return 0;       /* We don't tweek kernel, so just return 0 */
1559 }
1560 NOKPROBE_SYMBOL(kretprobe_dispatcher);
1561
1562 static struct trace_event_functions kretprobe_funcs = {
1563         .trace          = print_kretprobe_event
1564 };
1565
1566 static struct trace_event_functions kprobe_funcs = {
1567         .trace          = print_kprobe_event
1568 };
1569
1570 static inline void init_trace_event_call(struct trace_kprobe *tk)
1571 {
1572         struct trace_event_call *call = trace_probe_event_call(&tk->tp);
1573
1574         if (trace_kprobe_is_return(tk)) {
1575                 call->event.funcs = &kretprobe_funcs;
1576                 call->class->define_fields = kretprobe_event_define_fields;
1577         } else {
1578                 call->event.funcs = &kprobe_funcs;
1579                 call->class->define_fields = kprobe_event_define_fields;
1580         }
1581
1582         call->flags = TRACE_EVENT_FL_KPROBE;
1583         call->class->reg = kprobe_register;
1584 }
1585
1586 static int register_kprobe_event(struct trace_kprobe *tk)
1587 {
1588         init_trace_event_call(tk);
1589
1590         return trace_probe_register_event_call(&tk->tp);
1591 }
1592
1593 static int unregister_kprobe_event(struct trace_kprobe *tk)
1594 {
1595         return trace_probe_unregister_event_call(&tk->tp);
1596 }
1597
1598 #ifdef CONFIG_PERF_EVENTS
1599 /* create a trace_kprobe, but don't add it to global lists */
1600 struct trace_event_call *
1601 create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
1602                           bool is_return)
1603 {
1604         struct trace_kprobe *tk;
1605         int ret;
1606         char *event;
1607
1608         /*
1609          * local trace_kprobes are not added to dyn_event, so they are never
1610          * searched in find_trace_kprobe(). Therefore, there is no concern of
1611          * duplicated name here.
1612          */
1613         event = func ? func : "DUMMY_EVENT";
1614
1615         tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
1616                                 offs, 0 /* maxactive */, 0 /* nargs */,
1617                                 is_return);
1618
1619         if (IS_ERR(tk)) {
1620                 pr_info("Failed to allocate trace_probe.(%d)\n",
1621                         (int)PTR_ERR(tk));
1622                 return ERR_CAST(tk);
1623         }
1624
1625         init_trace_event_call(tk);
1626
1627         if (traceprobe_set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
1628                 ret = -ENOMEM;
1629                 goto error;
1630         }
1631
1632         ret = __register_trace_kprobe(tk);
1633         if (ret < 0)
1634                 goto error;
1635
1636         return trace_probe_event_call(&tk->tp);
1637 error:
1638         free_trace_kprobe(tk);
1639         return ERR_PTR(ret);
1640 }
1641
1642 void destroy_local_trace_kprobe(struct trace_event_call *event_call)
1643 {
1644         struct trace_kprobe *tk;
1645
1646         tk = trace_kprobe_primary_from_call(event_call);
1647         if (unlikely(!tk))
1648                 return;
1649
1650         if (trace_probe_is_enabled(&tk->tp)) {
1651                 WARN_ON(1);
1652                 return;
1653         }
1654
1655         __unregister_trace_kprobe(tk);
1656
1657         free_trace_kprobe(tk);
1658 }
1659 #endif /* CONFIG_PERF_EVENTS */
1660
1661 static __init void enable_boot_kprobe_events(void)
1662 {
1663         struct trace_array *tr = top_trace_array();
1664         struct trace_event_file *file;
1665         struct trace_kprobe *tk;
1666         struct dyn_event *pos;
1667
1668         mutex_lock(&event_mutex);
1669         for_each_trace_kprobe(tk, pos) {
1670                 list_for_each_entry(file, &tr->events, list)
1671                         if (file->event_call == trace_probe_event_call(&tk->tp))
1672                                 trace_event_enable_disable(file, 1, 0);
1673         }
1674         mutex_unlock(&event_mutex);
1675 }
1676
1677 static __init void setup_boot_kprobe_events(void)
1678 {
1679         char *p, *cmd = kprobe_boot_events_buf;
1680         int ret;
1681
1682         strreplace(kprobe_boot_events_buf, ',', ' ');
1683
1684         while (cmd && *cmd != '\0') {
1685                 p = strchr(cmd, ';');
1686                 if (p)
1687                         *p++ = '\0';
1688
1689                 ret = trace_run_command(cmd, create_or_delete_trace_kprobe);
1690                 if (ret)
1691                         pr_warn("Failed to add event(%d): %s\n", ret, cmd);
1692                 else
1693                         kprobe_boot_events_enabled = true;
1694
1695                 cmd = p;
1696         }
1697
1698         enable_boot_kprobe_events();
1699 }
1700
1701 /* Make a tracefs interface for controlling probe points */
1702 static __init int init_kprobe_trace(void)
1703 {
1704         struct dentry *d_tracer;
1705         struct dentry *entry;
1706         int ret;
1707
1708         ret = dyn_event_register(&trace_kprobe_ops);
1709         if (ret)
1710                 return ret;
1711
1712         if (register_module_notifier(&trace_kprobe_module_nb))
1713                 return -EINVAL;
1714
1715         d_tracer = tracing_init_dentry();
1716         if (IS_ERR(d_tracer))
1717                 return 0;
1718
1719         entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
1720                                     NULL, &kprobe_events_ops);
1721
1722         /* Event list interface */
1723         if (!entry)
1724                 pr_warn("Could not create tracefs 'kprobe_events' entry\n");
1725
1726         /* Profile interface */
1727         entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
1728                                     NULL, &kprobe_profile_ops);
1729
1730         if (!entry)
1731                 pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
1732
1733         setup_boot_kprobe_events();
1734
1735         return 0;
1736 }
1737 fs_initcall(init_kprobe_trace);
1738
1739
1740 #ifdef CONFIG_FTRACE_STARTUP_TEST
1741 static __init struct trace_event_file *
1742 find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
1743 {
1744         struct trace_event_file *file;
1745
1746         list_for_each_entry(file, &tr->events, list)
1747                 if (file->event_call == trace_probe_event_call(&tk->tp))
1748                         return file;
1749
1750         return NULL;
1751 }
1752
1753 /*
1754  * Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
1755  * stage, we can do this lockless.
1756  */
1757 static __init int kprobe_trace_self_tests_init(void)
1758 {
1759         int ret, warn = 0;
1760         int (*target)(int, int, int, int, int, int);
1761         struct trace_kprobe *tk;
1762         struct trace_event_file *file;
1763
1764         if (tracing_is_disabled())
1765                 return -ENODEV;
1766
1767         if (kprobe_boot_events_enabled) {
1768                 pr_info("Skipping kprobe tests due to kprobe_event on cmdline\n");
1769                 return 0;
1770         }
1771
1772         target = kprobe_trace_selftest_target;
1773
1774         pr_info("Testing kprobe tracing: ");
1775
1776         ret = trace_run_command("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)",
1777                                 create_or_delete_trace_kprobe);
1778         if (WARN_ON_ONCE(ret)) {
1779                 pr_warn("error on probing function entry.\n");
1780                 warn++;
1781         } else {
1782                 /* Enable trace point */
1783                 tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1784                 if (WARN_ON_ONCE(tk == NULL)) {
1785                         pr_warn("error on getting new probe.\n");
1786                         warn++;
1787                 } else {
1788                         file = find_trace_probe_file(tk, top_trace_array());
1789                         if (WARN_ON_ONCE(file == NULL)) {
1790                                 pr_warn("error on getting probe file.\n");
1791                                 warn++;
1792                         } else
1793                                 enable_trace_kprobe(
1794                                         trace_probe_event_call(&tk->tp), file);
1795                 }
1796         }
1797
1798         ret = trace_run_command("r:testprobe2 kprobe_trace_selftest_target $retval",
1799                                 create_or_delete_trace_kprobe);
1800         if (WARN_ON_ONCE(ret)) {
1801                 pr_warn("error on probing function return.\n");
1802                 warn++;
1803         } else {
1804                 /* Enable trace point */
1805                 tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1806                 if (WARN_ON_ONCE(tk == NULL)) {
1807                         pr_warn("error on getting 2nd new probe.\n");
1808                         warn++;
1809                 } else {
1810                         file = find_trace_probe_file(tk, top_trace_array());
1811                         if (WARN_ON_ONCE(file == NULL)) {
1812                                 pr_warn("error on getting probe file.\n");
1813                                 warn++;
1814                         } else
1815                                 enable_trace_kprobe(
1816                                         trace_probe_event_call(&tk->tp), file);
1817                 }
1818         }
1819
1820         if (warn)
1821                 goto end;
1822
1823         ret = target(1, 2, 3, 4, 5, 6);
1824
1825         /*
1826          * Not expecting an error here, the check is only to prevent the
1827          * optimizer from removing the call to target() as otherwise there
1828          * are no side-effects and the call is never performed.
1829          */
1830         if (ret != 21)
1831                 warn++;
1832
1833         /* Disable trace points before removing it */
1834         tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
1835         if (WARN_ON_ONCE(tk == NULL)) {
1836                 pr_warn("error on getting test probe.\n");
1837                 warn++;
1838         } else {
1839                 if (trace_kprobe_nhit(tk) != 1) {
1840                         pr_warn("incorrect number of testprobe hits\n");
1841                         warn++;
1842                 }
1843
1844                 file = find_trace_probe_file(tk, top_trace_array());
1845                 if (WARN_ON_ONCE(file == NULL)) {
1846                         pr_warn("error on getting probe file.\n");
1847                         warn++;
1848                 } else
1849                         disable_trace_kprobe(
1850                                 trace_probe_event_call(&tk->tp), file);
1851         }
1852
1853         tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
1854         if (WARN_ON_ONCE(tk == NULL)) {
1855                 pr_warn("error on getting 2nd test probe.\n");
1856                 warn++;
1857         } else {
1858                 if (trace_kprobe_nhit(tk) != 1) {
1859                         pr_warn("incorrect number of testprobe2 hits\n");
1860                         warn++;
1861                 }
1862
1863                 file = find_trace_probe_file(tk, top_trace_array());
1864                 if (WARN_ON_ONCE(file == NULL)) {
1865                         pr_warn("error on getting probe file.\n");
1866                         warn++;
1867                 } else
1868                         disable_trace_kprobe(
1869                                 trace_probe_event_call(&tk->tp), file);
1870         }
1871
1872         ret = trace_run_command("-:testprobe", create_or_delete_trace_kprobe);
1873         if (WARN_ON_ONCE(ret)) {
1874                 pr_warn("error on deleting a probe.\n");
1875                 warn++;
1876         }
1877
1878         ret = trace_run_command("-:testprobe2", create_or_delete_trace_kprobe);
1879         if (WARN_ON_ONCE(ret)) {
1880                 pr_warn("error on deleting a probe.\n");
1881                 warn++;
1882         }
1883
1884 end:
1885         ret = dyn_events_release_all(&trace_kprobe_ops);
1886         if (WARN_ON_ONCE(ret)) {
1887                 pr_warn("error on cleaning up probes.\n");
1888                 warn++;
1889         }
1890         /*
1891          * Wait for the optimizer work to finish. Otherwise it might fiddle
1892          * with probes in already freed __init text.
1893          */
1894         wait_for_kprobe_optimizer();
1895         if (warn)
1896                 pr_cont("NG: Some tests are failed. Please check them.\n");
1897         else
1898                 pr_cont("OK\n");
1899         return 0;
1900 }
1901
1902 late_initcall(kprobe_trace_self_tests_init);
1903
1904 #endif