kernel/trace/trace_fprobe.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Fprobe-based tracing events
   4  * Copyright (C) 2022 Google LLC.
   5  */
   6 #define pr_fmt(fmt)     "trace_fprobe: " fmt
   7
   8 #include <linux/fprobe.h>
   9 #include <linux/module.h>
  10 #include <linux/rculist.h>
  11 #include <linux/security.h>
  12 #include <linux/tracepoint.h>
  13 #include <linux/uaccess.h>
  14
  15 #include "trace_dynevent.h"
  16 #include "trace_probe.h"
  17 #include "trace_probe_kernel.h"
  18 #include "trace_probe_tmpl.h"
  19
  20 #define FPROBE_EVENT_SYSTEM "fprobes"
  21 #define TRACEPOINT_EVENT_SYSTEM "tracepoints"
  22 #define RETHOOK_MAXACTIVE_MAX 4096
  23
  24 static int trace_fprobe_create(const char *raw_command);
  25 static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev);
  26 static int trace_fprobe_release(struct dyn_event *ev);
  27 static bool trace_fprobe_is_busy(struct dyn_event *ev);
  28 static bool trace_fprobe_match(const char *system, const char *event,
  29                         int argc, const char **argv, struct dyn_event *ev);
  30
  31 static struct dyn_event_operations trace_fprobe_ops = {
  32         .create = trace_fprobe_create,
  33         .show = trace_fprobe_show,
  34         .is_busy = trace_fprobe_is_busy,
  35         .free = trace_fprobe_release,
  36         .match = trace_fprobe_match,
  37 };
  38
  39 /*
  40  * Fprobe event core functions
  41  */
  42 struct trace_fprobe {
  43         struct dyn_event        devent;
  44         struct fprobe           fp;
  45         const char              *symbol;
  46         struct tracepoint       *tpoint;
  47         struct module           *mod;
  48         struct trace_probe      tp;
  49 };
  50
  51 static bool is_trace_fprobe(struct dyn_event *ev)
  52 {
  53         return ev->ops == &trace_fprobe_ops;
  54 }
  55
  56 static struct trace_fprobe *to_trace_fprobe(struct dyn_event *ev)
  57 {
  58         return container_of(ev, struct trace_fprobe, devent);
  59 }
  60
  61 /**
  62  * for_each_trace_fprobe - iterate over the trace_fprobe list
  63  * @pos:        the struct trace_fprobe * for each entry
  64  * @dpos:       the struct dyn_event * to use as a loop cursor
  65  */
  66 #define for_each_trace_fprobe(pos, dpos)        \
  67         for_each_dyn_event(dpos)                \
  68                 if (is_trace_fprobe(dpos) && (pos = to_trace_fprobe(dpos)))
  69
  70 static bool trace_fprobe_is_return(struct trace_fprobe *tf)
  71 {
  72         return tf->fp.exit_handler != NULL;
  73 }
  74
  75 static bool trace_fprobe_is_tracepoint(struct trace_fprobe *tf)
  76 {
  77         return tf->tpoint != NULL;
  78 }
  79
  80 static const char *trace_fprobe_symbol(struct trace_fprobe *tf)
  81 {
  82         return tf->symbol ? tf->symbol : "unknown";
  83 }
  84
  85 static bool trace_fprobe_is_busy(struct dyn_event *ev)
  86 {
  87         struct trace_fprobe *tf = to_trace_fprobe(ev);
  88
  89         return trace_probe_is_enabled(&tf->tp);
  90 }
  91
  92 static bool trace_fprobe_match_command_head(struct trace_fprobe *tf,
  93                                             int argc, const char **argv)
  94 {
  95         char buf[MAX_ARGSTR_LEN + 1];
  96
  97         if (!argc)
  98                 return true;
  99
 100         snprintf(buf, sizeof(buf), "%s", trace_fprobe_symbol(tf));
 101         if (strcmp(buf, argv[0]))
 102                 return false;
 103         argc--; argv++;
 104
 105         return trace_probe_match_command_args(&tf->tp, argc, argv);
 106 }
 107
 108 static bool trace_fprobe_match(const char *system, const char *event,
 109                         int argc, const char **argv, struct dyn_event *ev)
 110 {
 111         struct trace_fprobe *tf = to_trace_fprobe(ev);
 112
 113         if (event[0] != '\0' && strcmp(trace_probe_name(&tf->tp), event))
 114                 return false;
 115
 116         if (system && strcmp(trace_probe_group_name(&tf->tp), system))
 117                 return false;
 118
 119         return trace_fprobe_match_command_head(tf, argc, argv);
 120 }
 121
 122 static bool trace_fprobe_is_registered(struct trace_fprobe *tf)
 123 {
 124         return fprobe_is_registered(&tf->fp);
 125 }
 126
 127 /*
 128  * Note that we don't verify the fetch_insn code, since it does not come
 129  * from user space.
 130  */
 131 static int
 132 process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 133                    void *base)
 134 {
 135         struct pt_regs *regs = rec;
 136         unsigned long val;
 137         int ret;
 138
 139 retry:
 140         /* 1st stage: get value from context */
 141         switch (code->op) {
 142         case FETCH_OP_STACK:
 143                 val = regs_get_kernel_stack_nth(regs, code->param);
 144                 break;
 145         case FETCH_OP_STACKP:
 146                 val = kernel_stack_pointer(regs);
 147                 break;
 148         case FETCH_OP_RETVAL:
 149                 val = regs_return_value(regs);
 150                 break;
 151 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
 152         case FETCH_OP_ARG:
 153                 val = regs_get_kernel_argument(regs, code->param);
 154                 break;
 155 #endif
 156         case FETCH_NOP_SYMBOL:  /* Ignore a place holder */
 157                 code++;
 158                 goto retry;
 159         default:
 160                 ret = process_common_fetch_insn(code, &val);
 161                 if (ret < 0)
 162                         return ret;
 163         }
 164         code++;
 165
 166         return process_fetch_insn_bottom(code, val, dest, base);
 167 }
 168 NOKPROBE_SYMBOL(process_fetch_insn)
 169
 170 /* function entry handler */
 171 static nokprobe_inline void
 172 __fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 173                     struct pt_regs *regs,
 174                     struct trace_event_file *trace_file)
 175 {
 176         struct fentry_trace_entry_head *entry;
 177         struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 178         struct trace_event_buffer fbuffer;
 179         int dsize;
 180
 181         if (WARN_ON_ONCE(call != trace_file->event_call))
 182                 return;
 183
 184         if (trace_trigger_soft_disabled(trace_file))
 185                 return;
 186
 187         dsize = __get_data_size(&tf->tp, regs);
 188
 189         entry = trace_event_buffer_reserve(&fbuffer, trace_file,
 190                                            sizeof(*entry) + tf->tp.size + dsize);
 191         if (!entry)
 192                 return;
 193
 194         fbuffer.regs = regs;
 195         entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
 196         entry->ip = entry_ip;
 197         store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
 198
 199         trace_event_buffer_commit(&fbuffer);
 200 }
 201
 202 static void
 203 fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 204                   struct pt_regs *regs)
 205 {
 206         struct event_file_link *link;
 207
 208         trace_probe_for_each_link_rcu(link, &tf->tp)
 209                 __fentry_trace_func(tf, entry_ip, regs, link->file);
 210 }
 211 NOKPROBE_SYMBOL(fentry_trace_func);
 212
 213 /* Kretprobe handler */
 214 static nokprobe_inline void
 215 __fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 216                    unsigned long ret_ip, struct pt_regs *regs,
 217                    struct trace_event_file *trace_file)
 218 {
 219         struct fexit_trace_entry_head *entry;
 220         struct trace_event_buffer fbuffer;
 221         struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 222         int dsize;
 223
 224         if (WARN_ON_ONCE(call != trace_file->event_call))
 225                 return;
 226
 227         if (trace_trigger_soft_disabled(trace_file))
 228                 return;
 229
 230         dsize = __get_data_size(&tf->tp, regs);
 231
 232         entry = trace_event_buffer_reserve(&fbuffer, trace_file,
 233                                            sizeof(*entry) + tf->tp.size + dsize);
 234         if (!entry)
 235                 return;
 236
 237         fbuffer.regs = regs;
 238         entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
 239         entry->func = entry_ip;
 240         entry->ret_ip = ret_ip;
 241         store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
 242
 243         trace_event_buffer_commit(&fbuffer);
 244 }
 245
 246 static void
 247 fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
 248                  unsigned long ret_ip, struct pt_regs *regs)
 249 {
 250         struct event_file_link *link;
 251
 252         trace_probe_for_each_link_rcu(link, &tf->tp)
 253                 __fexit_trace_func(tf, entry_ip, ret_ip, regs, link->file);
 254 }
 255 NOKPROBE_SYMBOL(fexit_trace_func);
 256
 257 #ifdef CONFIG_PERF_EVENTS
 258
 259 static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
 260                             struct pt_regs *regs)
 261 {
 262         struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 263         struct fentry_trace_entry_head *entry;
 264         struct hlist_head *head;
 265         int size, __size, dsize;
 266         int rctx;
 267
 268         head = this_cpu_ptr(call->perf_events);
 269         if (hlist_empty(head))
 270                 return 0;
 271
 272         dsize = __get_data_size(&tf->tp, regs);
 273         __size = sizeof(*entry) + tf->tp.size + dsize;
 274         size = ALIGN(__size + sizeof(u32), sizeof(u64));
 275         size -= sizeof(u32);
 276
 277         entry = perf_trace_buf_alloc(size, NULL, &rctx);
 278         if (!entry)
 279                 return 0;
 280
 281         entry->ip = entry_ip;
 282         memset(&entry[1], 0, dsize);
 283         store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
 284         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
 285                               head, NULL);
 286         return 0;
 287 }
 288 NOKPROBE_SYMBOL(fentry_perf_func);
 289
 290 static void
 291 fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
 292                 unsigned long ret_ip, struct pt_regs *regs)
 293 {
 294         struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 295         struct fexit_trace_entry_head *entry;
 296         struct hlist_head *head;
 297         int size, __size, dsize;
 298         int rctx;
 299
 300         head = this_cpu_ptr(call->perf_events);
 301         if (hlist_empty(head))
 302                 return;
 303
 304         dsize = __get_data_size(&tf->tp, regs);
 305         __size = sizeof(*entry) + tf->tp.size + dsize;
 306         size = ALIGN(__size + sizeof(u32), sizeof(u64));
 307         size -= sizeof(u32);
 308
 309         entry = perf_trace_buf_alloc(size, NULL, &rctx);
 310         if (!entry)
 311                 return;
 312
 313         entry->func = entry_ip;
 314         entry->ret_ip = ret_ip;
 315         store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
 316         perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
 317                               head, NULL);
 318 }
 319 NOKPROBE_SYMBOL(fexit_perf_func);
 320 #endif  /* CONFIG_PERF_EVENTS */
 321
 322 static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
 323                              unsigned long ret_ip, struct pt_regs *regs,
 324                              void *entry_data)
 325 {
 326         struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
 327         int ret = 0;
 328
 329         if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
 330                 fentry_trace_func(tf, entry_ip, regs);
 331 #ifdef CONFIG_PERF_EVENTS
 332         if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
 333                 ret = fentry_perf_func(tf, entry_ip, regs);
 334 #endif
 335         return ret;
 336 }
 337 NOKPROBE_SYMBOL(fentry_dispatcher);
 338
 339 static void fexit_dispatcher(struct fprobe *fp, unsigned long entry_ip,
 340                              unsigned long ret_ip, struct pt_regs *regs,
 341                              void *entry_data)
 342 {
 343         struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
 344
 345         if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
 346                 fexit_trace_func(tf, entry_ip, ret_ip, regs);
 347 #ifdef CONFIG_PERF_EVENTS
 348         if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
 349                 fexit_perf_func(tf, entry_ip, ret_ip, regs);
 350 #endif
 351 }
 352 NOKPROBE_SYMBOL(fexit_dispatcher);
 353
 354 static void free_trace_fprobe(struct trace_fprobe *tf)
 355 {
 356         if (tf) {
 357                 trace_probe_cleanup(&tf->tp);
 358                 kfree(tf->symbol);
 359                 kfree(tf);
 360         }
 361 }
 362
 363 /*
 364  * Allocate new trace_probe and initialize it (including fprobe).
 365  */
 366 static struct trace_fprobe *alloc_trace_fprobe(const char *group,
 367                                                const char *event,
 368                                                const char *symbol,
 369                                                struct tracepoint *tpoint,
 370                                                int maxactive,
 371                                                int nargs, bool is_return)
 372 {
 373         struct trace_fprobe *tf;
 374         int ret = -ENOMEM;
 375
 376         tf = kzalloc(struct_size(tf, tp.args, nargs), GFP_KERNEL);
 377         if (!tf)
 378                 return ERR_PTR(ret);
 379
 380         tf->symbol = kstrdup(symbol, GFP_KERNEL);
 381         if (!tf->symbol)
 382                 goto error;
 383
 384         if (is_return)
 385                 tf->fp.exit_handler = fexit_dispatcher;
 386         else
 387                 tf->fp.entry_handler = fentry_dispatcher;
 388
 389         tf->tpoint = tpoint;
 390         tf->fp.nr_maxactive = maxactive;
 391
 392         ret = trace_probe_init(&tf->tp, event, group, false);
 393         if (ret < 0)
 394                 goto error;
 395
 396         dyn_event_init(&tf->devent, &trace_fprobe_ops);
 397         return tf;
 398 error:
 399         free_trace_fprobe(tf);
 400         return ERR_PTR(ret);
 401 }
 402
 403 static struct trace_fprobe *find_trace_fprobe(const char *event,
 404                                               const char *group)
 405 {
 406         struct dyn_event *pos;
 407         struct trace_fprobe *tf;
 408
 409         for_each_trace_fprobe(tf, pos)
 410                 if (strcmp(trace_probe_name(&tf->tp), event) == 0 &&
 411                     strcmp(trace_probe_group_name(&tf->tp), group) == 0)
 412                         return tf;
 413         return NULL;
 414 }
 415
 416 static inline int __enable_trace_fprobe(struct trace_fprobe *tf)
 417 {
 418         if (trace_fprobe_is_registered(tf))
 419                 enable_fprobe(&tf->fp);
 420
 421         return 0;
 422 }
 423
 424 static void __disable_trace_fprobe(struct trace_probe *tp)
 425 {
 426         struct trace_fprobe *tf;
 427
 428         list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list) {
 429                 if (!trace_fprobe_is_registered(tf))
 430                         continue;
 431                 disable_fprobe(&tf->fp);
 432         }
 433 }
 434
 435 /*
 436  * Enable trace_probe
 437  * if the file is NULL, enable "perf" handler, or enable "trace" handler.
 438  */
 439 static int enable_trace_fprobe(struct trace_event_call *call,
 440                                struct trace_event_file *file)
 441 {
 442         struct trace_probe *tp;
 443         struct trace_fprobe *tf;
 444         bool enabled;
 445         int ret = 0;
 446
 447         tp = trace_probe_primary_from_call(call);
 448         if (WARN_ON_ONCE(!tp))
 449                 return -ENODEV;
 450         enabled = trace_probe_is_enabled(tp);
 451
 452         /* This also changes "enabled" state */
 453         if (file) {
 454                 ret = trace_probe_add_file(tp, file);
 455                 if (ret)
 456                         return ret;
 457         } else
 458                 trace_probe_set_flag(tp, TP_FLAG_PROFILE);
 459
 460         if (!enabled) {
 461                 list_for_each_entry(tf, trace_probe_probe_list(tp), tp.list) {
 462                         /* TODO: check the fprobe is gone */
 463                         __enable_trace_fprobe(tf);
 464                 }
 465         }
 466
 467         return 0;
 468 }
 469
 470 /*
 471  * Disable trace_probe
 472  * if the file is NULL, disable "perf" handler, or disable "trace" handler.
 473  */
 474 static int disable_trace_fprobe(struct trace_event_call *call,
 475                                 struct trace_event_file *file)
 476 {
 477         struct trace_probe *tp;
 478
 479         tp = trace_probe_primary_from_call(call);
 480         if (WARN_ON_ONCE(!tp))
 481                 return -ENODEV;
 482
 483         if (file) {
 484                 if (!trace_probe_get_file_link(tp, file))
 485                         return -ENOENT;
 486                 if (!trace_probe_has_single_file(tp))
 487                         goto out;
 488                 trace_probe_clear_flag(tp, TP_FLAG_TRACE);
 489         } else
 490                 trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
 491
 492         if (!trace_probe_is_enabled(tp))
 493                 __disable_trace_fprobe(tp);
 494
 495  out:
 496         if (file)
 497                 /*
 498                  * Synchronization is done in below function. For perf event,
 499                  * file == NULL and perf_trace_event_unreg() calls
 500                  * tracepoint_synchronize_unregister() to ensure synchronize
 501                  * event. We don't need to care about it.
 502                  */
 503                 trace_probe_remove_file(tp, file);
 504
 505         return 0;
 506 }
 507
 508 /* Event entry printers */
 509 static enum print_line_t
 510 print_fentry_event(struct trace_iterator *iter, int flags,
 511                    struct trace_event *event)
 512 {
 513         struct fentry_trace_entry_head *field;
 514         struct trace_seq *s = &iter->seq;
 515         struct trace_probe *tp;
 516
 517         field = (struct fentry_trace_entry_head *)iter->ent;
 518         tp = trace_probe_primary_from_call(
 519                 container_of(event, struct trace_event_call, event));
 520         if (WARN_ON_ONCE(!tp))
 521                 goto out;
 522
 523         trace_seq_printf(s, "%s: (", trace_probe_name(tp));
 524
 525         if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
 526                 goto out;
 527
 528         trace_seq_putc(s, ')');
 529
 530         if (trace_probe_print_args(s, tp->args, tp->nr_args,
 531                              (u8 *)&field[1], field) < 0)
 532                 goto out;
 533
 534         trace_seq_putc(s, '\n');
 535  out:
 536         return trace_handle_return(s);
 537 }
 538
 539 static enum print_line_t
 540 print_fexit_event(struct trace_iterator *iter, int flags,
 541                   struct trace_event *event)
 542 {
 543         struct fexit_trace_entry_head *field;
 544         struct trace_seq *s = &iter->seq;
 545         struct trace_probe *tp;
 546
 547         field = (struct fexit_trace_entry_head *)iter->ent;
 548         tp = trace_probe_primary_from_call(
 549                 container_of(event, struct trace_event_call, event));
 550         if (WARN_ON_ONCE(!tp))
 551                 goto out;
 552
 553         trace_seq_printf(s, "%s: (", trace_probe_name(tp));
 554
 555         if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
 556                 goto out;
 557
 558         trace_seq_puts(s, " <- ");
 559
 560         if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
 561                 goto out;
 562
 563         trace_seq_putc(s, ')');
 564
 565         if (trace_probe_print_args(s, tp->args, tp->nr_args,
 566                              (u8 *)&field[1], field) < 0)
 567                 goto out;
 568
 569         trace_seq_putc(s, '\n');
 570
 571  out:
 572         return trace_handle_return(s);
 573 }
 574
 575 static int fentry_event_define_fields(struct trace_event_call *event_call)
 576 {
 577         int ret;
 578         struct fentry_trace_entry_head field;
 579         struct trace_probe *tp;
 580
 581         tp = trace_probe_primary_from_call(event_call);
 582         if (WARN_ON_ONCE(!tp))
 583                 return -ENOENT;
 584
 585         DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
 586
 587         return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
 588 }
 589
 590 static int fexit_event_define_fields(struct trace_event_call *event_call)
 591 {
 592         int ret;
 593         struct fexit_trace_entry_head field;
 594         struct trace_probe *tp;
 595
 596         tp = trace_probe_primary_from_call(event_call);
 597         if (WARN_ON_ONCE(!tp))
 598                 return -ENOENT;
 599
 600         DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
 601         DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
 602
 603         return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
 604 }
 605
 606 static struct trace_event_functions fentry_funcs = {
 607         .trace          = print_fentry_event
 608 };
 609
 610 static struct trace_event_functions fexit_funcs = {
 611         .trace          = print_fexit_event
 612 };
 613
 614 static struct trace_event_fields fentry_fields_array[] = {
 615         { .type = TRACE_FUNCTION_TYPE,
 616           .define_fields = fentry_event_define_fields },
 617         {}
 618 };
 619
 620 static struct trace_event_fields fexit_fields_array[] = {
 621         { .type = TRACE_FUNCTION_TYPE,
 622           .define_fields = fexit_event_define_fields },
 623         {}
 624 };
 625
 626 static int fprobe_register(struct trace_event_call *event,
 627                            enum trace_reg type, void *data);
 628
 629 static inline void init_trace_event_call(struct trace_fprobe *tf)
 630 {
 631         struct trace_event_call *call = trace_probe_event_call(&tf->tp);
 632
 633         if (trace_fprobe_is_return(tf)) {
 634                 call->event.funcs = &fexit_funcs;
 635                 call->class->fields_array = fexit_fields_array;
 636         } else {
 637                 call->event.funcs = &fentry_funcs;
 638                 call->class->fields_array = fentry_fields_array;
 639         }
 640
 641         call->flags = TRACE_EVENT_FL_FPROBE;
 642         call->class->reg = fprobe_register;
 643 }
 644
 645 static int register_fprobe_event(struct trace_fprobe *tf)
 646 {
 647         init_trace_event_call(tf);
 648
 649         return trace_probe_register_event_call(&tf->tp);
 650 }
 651
 652 static int unregister_fprobe_event(struct trace_fprobe *tf)
 653 {
 654         return trace_probe_unregister_event_call(&tf->tp);
 655 }
 656
 657 /* Internal register function - just handle fprobe and flags */
 658 static int __register_trace_fprobe(struct trace_fprobe *tf)
 659 {
 660         int i, ret;
 661
 662         /* Should we need new LOCKDOWN flag for fprobe? */
 663         ret = security_locked_down(LOCKDOWN_KPROBES);
 664         if (ret)
 665                 return ret;
 666
 667         if (trace_fprobe_is_registered(tf))
 668                 return -EINVAL;
 669
 670         for (i = 0; i < tf->tp.nr_args; i++) {
 671                 ret = traceprobe_update_arg(&tf->tp.args[i]);
 672                 if (ret)
 673                         return ret;
 674         }
 675
 676         /* Set/clear disabled flag according to tp->flag */
 677         if (trace_probe_is_enabled(&tf->tp))
 678                 tf->fp.flags &= ~FPROBE_FL_DISABLED;
 679         else
 680                 tf->fp.flags |= FPROBE_FL_DISABLED;
 681
 682         if (trace_fprobe_is_tracepoint(tf)) {
 683                 struct tracepoint *tpoint = tf->tpoint;
 684                 unsigned long ip = (unsigned long)tpoint->probestub;
 685                 /*
 686                  * Here, we do 2 steps to enable fprobe on a tracepoint.
 687                  * At first, put __probestub_##TP function on the tracepoint
 688                  * and put a fprobe on the stub function.
 689                  */
 690                 ret = tracepoint_probe_register_prio_may_exist(tpoint,
 691                                         tpoint->probestub, NULL, 0);
 692                 if (ret < 0)
 693                         return ret;
 694                 return register_fprobe_ips(&tf->fp, &ip, 1);
 695         }
 696
 697         /* TODO: handle filter, nofilter or symbol list */
 698         return register_fprobe(&tf->fp, tf->symbol, NULL);
 699 }
 700
 701 /* Internal unregister function - just handle fprobe and flags */
 702 static void __unregister_trace_fprobe(struct trace_fprobe *tf)
 703 {
 704         if (trace_fprobe_is_registered(tf)) {
 705                 unregister_fprobe(&tf->fp);
 706                 memset(&tf->fp, 0, sizeof(tf->fp));
 707                 if (trace_fprobe_is_tracepoint(tf)) {
 708                         tracepoint_probe_unregister(tf->tpoint,
 709                                         tf->tpoint->probestub, NULL);
 710                         tf->tpoint = NULL;
 711                         tf->mod = NULL;
 712                 }
 713         }
 714 }
 715
 716 /* TODO: make this trace_*probe common function */
 717 /* Unregister a trace_probe and probe_event */
 718 static int unregister_trace_fprobe(struct trace_fprobe *tf)
 719 {
 720         /* If other probes are on the event, just unregister fprobe */
 721         if (trace_probe_has_sibling(&tf->tp))
 722                 goto unreg;
 723
 724         /* Enabled event can not be unregistered */
 725         if (trace_probe_is_enabled(&tf->tp))
 726                 return -EBUSY;
 727
 728         /* If there's a reference to the dynamic event */
 729         if (trace_event_dyn_busy(trace_probe_event_call(&tf->tp)))
 730                 return -EBUSY;
 731
 732         /* Will fail if probe is being used by ftrace or perf */
 733         if (unregister_fprobe_event(tf))
 734                 return -EBUSY;
 735
 736 unreg:
 737         __unregister_trace_fprobe(tf);
 738         dyn_event_remove(&tf->devent);
 739         trace_probe_unlink(&tf->tp);
 740
 741         return 0;
 742 }
 743
 744 static bool trace_fprobe_has_same_fprobe(struct trace_fprobe *orig,
 745                                          struct trace_fprobe *comp)
 746 {
 747         struct trace_probe_event *tpe = orig->tp.event;
 748         int i;
 749
 750         list_for_each_entry(orig, &tpe->probes, tp.list) {
 751                 if (strcmp(trace_fprobe_symbol(orig),
 752                            trace_fprobe_symbol(comp)))
 753                         continue;
 754
 755                 /*
 756                  * trace_probe_compare_arg_type() ensured that nr_args and
 757                  * each argument name and type are same. Let's compare comm.
 758                  */
 759                 for (i = 0; i < orig->tp.nr_args; i++) {
 760                         if (strcmp(orig->tp.args[i].comm,
 761                                    comp->tp.args[i].comm))
 762                                 break;
 763                 }
 764
 765                 if (i == orig->tp.nr_args)
 766                         return true;
 767         }
 768
 769         return false;
 770 }
 771
 772 static int append_trace_fprobe(struct trace_fprobe *tf, struct trace_fprobe *to)
 773 {
 774         int ret;
 775
 776         if (trace_fprobe_is_return(tf) != trace_fprobe_is_return(to) ||
 777             trace_fprobe_is_tracepoint(tf) != trace_fprobe_is_tracepoint(to)) {
 778                 trace_probe_log_set_index(0);
 779                 trace_probe_log_err(0, DIFF_PROBE_TYPE);
 780                 return -EEXIST;
 781         }
 782         ret = trace_probe_compare_arg_type(&tf->tp, &to->tp);
 783         if (ret) {
 784                 /* Note that argument starts index = 2 */
 785                 trace_probe_log_set_index(ret + 1);
 786                 trace_probe_log_err(0, DIFF_ARG_TYPE);
 787                 return -EEXIST;
 788         }
 789         if (trace_fprobe_has_same_fprobe(to, tf)) {
 790                 trace_probe_log_set_index(0);
 791                 trace_probe_log_err(0, SAME_PROBE);
 792                 return -EEXIST;
 793         }
 794
 795         /* Append to existing event */
 796         ret = trace_probe_append(&tf->tp, &to->tp);
 797         if (ret)
 798                 return ret;
 799
 800         ret = __register_trace_fprobe(tf);
 801         if (ret)
 802                 trace_probe_unlink(&tf->tp);
 803         else
 804                 dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
 805
 806         return ret;
 807 }
 808
 809 /* Register a trace_probe and probe_event */
 810 static int register_trace_fprobe(struct trace_fprobe *tf)
 811 {
 812         struct trace_fprobe *old_tf;
 813         int ret;
 814
 815         mutex_lock(&event_mutex);
 816
 817         old_tf = find_trace_fprobe(trace_probe_name(&tf->tp),
 818                                    trace_probe_group_name(&tf->tp));
 819         if (old_tf) {
 820                 ret = append_trace_fprobe(tf, old_tf);
 821                 goto end;
 822         }
 823
 824         /* Register new event */
 825         ret = register_fprobe_event(tf);
 826         if (ret) {
 827                 if (ret == -EEXIST) {
 828                         trace_probe_log_set_index(0);
 829                         trace_probe_log_err(0, EVENT_EXIST);
 830                 } else
 831                         pr_warn("Failed to register probe event(%d)\n", ret);
 832                 goto end;
 833         }
 834
 835         /* Register fprobe */
 836         ret = __register_trace_fprobe(tf);
 837         if (ret < 0)
 838                 unregister_fprobe_event(tf);
 839         else
 840                 dyn_event_add(&tf->devent, trace_probe_event_call(&tf->tp));
 841
 842 end:
 843         mutex_unlock(&event_mutex);
 844         return ret;
 845 }
 846
 847 #ifdef CONFIG_MODULES
 848 static int __tracepoint_probe_module_cb(struct notifier_block *self,
 849                                         unsigned long val, void *data)
 850 {
 851         struct tp_module *tp_mod = data;
 852         struct trace_fprobe *tf;
 853         struct dyn_event *pos;
 854
 855         if (val != MODULE_STATE_GOING)
 856                 return NOTIFY_DONE;
 857
 858         mutex_lock(&event_mutex);
 859         for_each_trace_fprobe(tf, pos) {
 860                 if (tp_mod->mod == tf->mod) {
 861                         tracepoint_probe_unregister(tf->tpoint,
 862                                         tf->tpoint->probestub, NULL);
 863                         tf->tpoint = NULL;
 864                         tf->mod = NULL;
 865                 }
 866         }
 867         mutex_unlock(&event_mutex);
 868
 869         return NOTIFY_DONE;
 870 }
 871
 872 static struct notifier_block tracepoint_module_nb = {
 873         .notifier_call = __tracepoint_probe_module_cb,
 874 };
 875 #endif /* CONFIG_MODULES */
 876
 877 struct __find_tracepoint_cb_data {
 878         const char *tp_name;
 879         struct tracepoint *tpoint;
 880 };
 881
 882 static void __find_tracepoint_cb(struct tracepoint *tp, void *priv)
 883 {
 884         struct __find_tracepoint_cb_data *data = priv;
 885
 886         if (!data->tpoint && !strcmp(data->tp_name, tp->name))
 887                 data->tpoint = tp;
 888 }
 889
 890 static struct tracepoint *find_tracepoint(const char *tp_name)
 891 {
 892         struct __find_tracepoint_cb_data data = {
 893                 .tp_name = tp_name,
 894         };
 895
 896         for_each_kernel_tracepoint(__find_tracepoint_cb, &data);
 897
 898         return data.tpoint;
 899 }
 900
 901 static int parse_symbol_and_return(int argc, const char *argv[],
 902                                    char **symbol, bool *is_return,
 903                                    bool is_tracepoint)
 904 {
 905         char *tmp = strchr(argv[1], '%');
 906         int i;
 907
 908         if (tmp) {
 909                 int len = tmp - argv[1];
 910
 911                 if (!is_tracepoint && !strcmp(tmp, "%return")) {
 912                         *is_return = true;
 913                 } else {
 914                         trace_probe_log_err(len, BAD_ADDR_SUFFIX);
 915                         return -EINVAL;
 916                 }
 917                 *symbol = kmemdup_nul(argv[1], len, GFP_KERNEL);
 918         } else
 919                 *symbol = kstrdup(argv[1], GFP_KERNEL);
 920         if (!*symbol)
 921                 return -ENOMEM;
 922
 923         if (*is_return)
 924                 return 0;
 925
 926         /* If there is $retval, this should be a return fprobe. */
 927         for (i = 2; i < argc; i++) {
 928                 tmp = strstr(argv[i], "$retval");
 929                 if (tmp && !isalnum(tmp[7]) && tmp[7] != '_') {
 930                         if (is_tracepoint) {
 931                                 trace_probe_log_set_index(i);
 932                                 trace_probe_log_err(tmp - argv[i], RETVAL_ON_PROBE);
 933                                 return -EINVAL;
 934                         }
 935                         *is_return = true;
 936                         break;
 937                 }
 938         }
 939         return 0;
 940 }
 941
 942 static int __trace_fprobe_create(int argc, const char *argv[])
 943 {
 944         /*
 945          * Argument syntax:
 946          *  - Add fentry probe:
 947          *      f[:[GRP/][EVENT]] [MOD:]KSYM [FETCHARGS]
 948          *  - Add fexit probe:
 949          *      f[N][:[GRP/][EVENT]] [MOD:]KSYM%return [FETCHARGS]
 950          *  - Add tracepoint probe:
 951          *      t[:[GRP/][EVENT]] TRACEPOINT [FETCHARGS]
 952          *
 953          * Fetch args:
 954          *  $retval     : fetch return value
 955          *  $stack      : fetch stack address
 956          *  $stackN     : fetch Nth entry of stack (N:0-)
 957          *  $argN       : fetch Nth argument (N:1-)
 958          *  $comm       : fetch current task comm
 959          *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
 960          *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
 961          * Dereferencing memory fetch:
 962          *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
 963          * Alias name of args:
 964          *  NAME=FETCHARG : set NAME as alias of FETCHARG.
 965          * Type of args:
 966          *  FETCHARG:TYPE : use TYPE instead of unsigned long.
 967          */
 968         struct trace_fprobe *tf = NULL;
 969         int i, len, new_argc = 0, ret = 0;
 970         bool is_return = false;
 971         char *symbol = NULL;
 972         const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
 973         const char **new_argv = NULL;
 974         int maxactive = 0;
 975         char buf[MAX_EVENT_NAME_LEN];
 976         char gbuf[MAX_EVENT_NAME_LEN];
 977         char sbuf[KSYM_NAME_LEN];
 978         char abuf[MAX_BTF_ARGS_LEN];
 979         bool is_tracepoint = false;
 980         struct tracepoint *tpoint = NULL;
 981         struct traceprobe_parse_context ctx = {
 982                 .flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE,
 983         };
 984
 985         if ((argv[0][0] != 'f' && argv[0][0] != 't') || argc < 2)
 986                 return -ECANCELED;
 987
 988         if (argv[0][0] == 't') {
 989                 is_tracepoint = true;
 990                 group = TRACEPOINT_EVENT_SYSTEM;
 991         }
 992
 993         trace_probe_log_init("trace_fprobe", argc, argv);
 994
 995         event = strchr(&argv[0][1], ':');
 996         if (event)
 997                 event++;
 998
 999         if (isdigit(argv[0][1])) {
1000                 if (event)
1001                         len = event - &argv[0][1] - 1;
1002                 else
1003                         len = strlen(&argv[0][1]);
1004                 if (len > MAX_EVENT_NAME_LEN - 1) {
1005                         trace_probe_log_err(1, BAD_MAXACT);
1006                         goto parse_error;
1007                 }
1008                 memcpy(buf, &argv[0][1], len);
1009                 buf[len] = '\0';
1010                 ret = kstrtouint(buf, 0, &maxactive);
1011                 if (ret || !maxactive) {
1012                         trace_probe_log_err(1, BAD_MAXACT);
1013                         goto parse_error;
1014                 }
1015                 /* fprobe rethook instances are iterated over via a list. The
1016                  * maximum should stay reasonable.
1017                  */
1018                 if (maxactive > RETHOOK_MAXACTIVE_MAX) {
1019                         trace_probe_log_err(1, MAXACT_TOO_BIG);
1020                         goto parse_error;
1021                 }
1022         }
1023
1024         trace_probe_log_set_index(1);
1025
1026         /* a symbol(or tracepoint) must be specified */
1027         ret = parse_symbol_and_return(argc, argv, &symbol, &is_return, is_tracepoint);
1028         if (ret < 0)
1029                 goto parse_error;
1030
1031         if (!is_return && maxactive) {
1032                 trace_probe_log_set_index(0);
1033                 trace_probe_log_err(1, BAD_MAXACT_TYPE);
1034                 goto parse_error;
1035         }
1036
1037         trace_probe_log_set_index(0);
1038         if (event) {
1039                 ret = traceprobe_parse_event_name(&event, &group, gbuf,
1040                                                   event - argv[0]);
1041                 if (ret)
1042                         goto parse_error;
1043         }
1044
1045         if (!event) {
1046                 /* Make a new event name */
1047                 if (is_tracepoint)
1048                         snprintf(buf, MAX_EVENT_NAME_LEN, "%s%s",
1049                                  isdigit(*symbol) ? "_" : "", symbol);
1050                 else
1051                         snprintf(buf, MAX_EVENT_NAME_LEN, "%s__%s", symbol,
1052                                  is_return ? "exit" : "entry");
1053                 sanitize_event_name(buf);
1054                 event = buf;
1055         }
1056
1057         if (is_return)
1058                 ctx.flags |= TPARG_FL_RETURN;
1059         else
1060                 ctx.flags |= TPARG_FL_FENTRY;
1061
1062         if (is_tracepoint) {
1063                 ctx.flags |= TPARG_FL_TPOINT;
1064                 tpoint = find_tracepoint(symbol);
1065                 if (!tpoint) {
1066                         trace_probe_log_set_index(1);
1067                         trace_probe_log_err(0, NO_TRACEPOINT);
1068                         goto parse_error;
1069                 }
1070                 ctx.funcname = kallsyms_lookup(
1071                                 (unsigned long)tpoint->probestub,
1072                                 NULL, NULL, NULL, sbuf);
1073         } else
1074                 ctx.funcname = symbol;
1075
1076         argc -= 2; argv += 2;
1077         new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
1078                                                abuf, MAX_BTF_ARGS_LEN, &ctx);
1079         if (IS_ERR(new_argv)) {
1080                 ret = PTR_ERR(new_argv);
1081                 new_argv = NULL;
1082                 goto out;
1083         }
1084         if (new_argv) {
1085                 argc = new_argc;
1086                 argv = new_argv;
1087         }
1088
1089         /* setup a probe */
1090         tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
1091                                 argc, is_return);
1092         if (IS_ERR(tf)) {
1093                 ret = PTR_ERR(tf);
1094                 /* This must return -ENOMEM, else there is a bug */
1095                 WARN_ON_ONCE(ret != -ENOMEM);
1096                 goto out;       /* We know tf is not allocated */
1097         }
1098
1099         if (is_tracepoint)
1100                 tf->mod = __module_text_address(
1101                                 (unsigned long)tf->tpoint->probestub);
1102
1103         /* parse arguments */
1104         for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
1105                 trace_probe_log_set_index(i + 2);
1106                 ctx.offset = 0;
1107                 ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
1108                 if (ret)
1109                         goto error;     /* This can be -ENOMEM */
1110         }
1111
1112         ret = traceprobe_set_print_fmt(&tf->tp,
1113                         is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL);
1114         if (ret < 0)
1115                 goto error;
1116
1117         ret = register_trace_fprobe(tf);
1118         if (ret) {
1119                 trace_probe_log_set_index(1);
1120                 if (ret == -EILSEQ)
1121                         trace_probe_log_err(0, BAD_INSN_BNDRY);
1122                 else if (ret == -ENOENT)
1123                         trace_probe_log_err(0, BAD_PROBE_ADDR);
1124                 else if (ret != -ENOMEM && ret != -EEXIST)
1125                         trace_probe_log_err(0, FAIL_REG_PROBE);
1126                 goto error;
1127         }
1128
1129 out:
1130         traceprobe_finish_parse(&ctx);
1131         trace_probe_log_clear();
1132         kfree(new_argv);
1133         kfree(symbol);
1134         return ret;
1135
1136 parse_error:
1137         ret = -EINVAL;
1138 error:
1139         free_trace_fprobe(tf);
1140         goto out;
1141 }
1142
1143 static int trace_fprobe_create(const char *raw_command)
1144 {
1145         return trace_probe_create(raw_command, __trace_fprobe_create);
1146 }
1147
1148 static int trace_fprobe_release(struct dyn_event *ev)
1149 {
1150         struct trace_fprobe *tf = to_trace_fprobe(ev);
1151         int ret = unregister_trace_fprobe(tf);
1152
1153         if (!ret)
1154                 free_trace_fprobe(tf);
1155         return ret;
1156 }
1157
1158 static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev)
1159 {
1160         struct trace_fprobe *tf = to_trace_fprobe(ev);
1161         int i;
1162
1163         if (trace_fprobe_is_tracepoint(tf))
1164                 seq_putc(m, 't');
1165         else
1166                 seq_putc(m, 'f');
1167         if (trace_fprobe_is_return(tf) && tf->fp.nr_maxactive)
1168                 seq_printf(m, "%d", tf->fp.nr_maxactive);
1169         seq_printf(m, ":%s/%s", trace_probe_group_name(&tf->tp),
1170                                 trace_probe_name(&tf->tp));
1171
1172         seq_printf(m, " %s%s", trace_fprobe_symbol(tf),
1173                                trace_fprobe_is_return(tf) ? "%return" : "");
1174
1175         for (i = 0; i < tf->tp.nr_args; i++)
1176                 seq_printf(m, " %s=%s", tf->tp.args[i].name, tf->tp.args[i].comm);
1177         seq_putc(m, '\n');
1178
1179         return 0;
1180 }
1181
1182 /*
1183  * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
1184  */
1185 static int fprobe_register(struct trace_event_call *event,
1186                            enum trace_reg type, void *data)
1187 {
1188         struct trace_event_file *file = data;
1189
1190         switch (type) {
1191         case TRACE_REG_REGISTER:
1192                 return enable_trace_fprobe(event, file);
1193         case TRACE_REG_UNREGISTER:
1194                 return disable_trace_fprobe(event, file);
1195
1196 #ifdef CONFIG_PERF_EVENTS
1197         case TRACE_REG_PERF_REGISTER:
1198                 return enable_trace_fprobe(event, NULL);
1199         case TRACE_REG_PERF_UNREGISTER:
1200                 return disable_trace_fprobe(event, NULL);
1201         case TRACE_REG_PERF_OPEN:
1202         case TRACE_REG_PERF_CLOSE:
1203         case TRACE_REG_PERF_ADD:
1204         case TRACE_REG_PERF_DEL:
1205                 return 0;
1206 #endif
1207         }
1208         return 0;
1209 }
1210
1211 /*
1212  * Register dynevent at core_initcall. This allows kernel to setup fprobe
1213  * events in postcore_initcall without tracefs.
1214  */
1215 static __init int init_fprobe_trace_early(void)
1216 {
1217         int ret;
1218
1219         ret = dyn_event_register(&trace_fprobe_ops);
1220         if (ret)
1221                 return ret;
1222
1223 #ifdef CONFIG_MODULES
1224         ret = register_tracepoint_module_notifier(&tracepoint_module_nb);
1225         if (ret)
1226                 return ret;
1227 #endif
1228
1229         return 0;
1230 }
1231 core_initcall(init_fprobe_trace_early);