gdb/break-catch-syscall.c

   1 /* Everything about syscall catchpoints, for GDB.
   2
   3    Copyright (C) 2009-2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include <ctype.h>
  22 #include "breakpoint.h"
  23 #include "gdbcmd.h"
  24 #include "inferior.h"
  25 #include "cli/cli-utils.h"
  26 #include "annotate.h"
  27 #include "mi/mi-common.h"
  28 #include "valprint.h"
  29 #include "arch-utils.h"
  30 #include "observable.h"
  31 #include "xml-syscall.h"
  32
  33 /* An instance of this type is used to represent a syscall catchpoint.
  34    A breakpoint is really of this type iff its ops pointer points to
  35    CATCH_SYSCALL_BREAKPOINT_OPS.  */
  36
  37 struct syscall_catchpoint : public breakpoint
  38 {
  39   /* Syscall numbers used for the 'catch syscall' feature.  If no
  40      syscall has been specified for filtering, it is empty.
  41      Otherwise, it holds a list of all syscalls to be caught.  */
  42   std::vector<int> syscalls_to_be_caught;
  43 };
  44
  45 static const struct inferior_data *catch_syscall_inferior_data = NULL;
  46
  47 struct catch_syscall_inferior_data
  48 {
  49   /* We keep a count of the number of times the user has requested a
  50      particular syscall to be tracked, and pass this information to the
  51      target.  This lets capable targets implement filtering directly.  */
  52
  53   /* Number of times that "any" syscall is requested.  */
  54   int any_syscall_count;
  55
  56   /* Count of each system call.  */
  57   std::vector<int> syscalls_counts;
  58
  59   /* This counts all syscall catch requests, so we can readily determine
  60      if any catching is necessary.  */
  61   int total_syscalls_count;
  62 };
  63
  64 static struct catch_syscall_inferior_data *
  65 get_catch_syscall_inferior_data (struct inferior *inf)
  66 {
  67   struct catch_syscall_inferior_data *inf_data;
  68
  69   inf_data = ((struct catch_syscall_inferior_data *)
  70               inferior_data (inf, catch_syscall_inferior_data));
  71   if (inf_data == NULL)
  72     {
  73       inf_data = new struct catch_syscall_inferior_data ();
  74       set_inferior_data (inf, catch_syscall_inferior_data, inf_data);
  75     }
  76
  77   return inf_data;
  78 }
  79
  80 static void
  81 catch_syscall_inferior_data_cleanup (struct inferior *inf, void *arg)
  82 {
  83   struct catch_syscall_inferior_data *inf_data
  84     = (struct catch_syscall_inferior_data *) arg;
  85   delete inf_data;
  86 }
  87
  88
  89 /* Implement the "insert" breakpoint_ops method for syscall
  90    catchpoints.  */
  91
  92 static int
  93 insert_catch_syscall (struct bp_location *bl)
  94 {
  95   struct syscall_catchpoint *c = (struct syscall_catchpoint *) bl->owner;
  96   struct inferior *inf = current_inferior ();
  97   struct catch_syscall_inferior_data *inf_data
  98     = get_catch_syscall_inferior_data (inf);
  99
 100   ++inf_data->total_syscalls_count;
 101   if (c->syscalls_to_be_caught.empty ())
 102     ++inf_data->any_syscall_count;
 103   else
 104     {
 105       for (int iter : c->syscalls_to_be_caught)
 106         {
 107           if (iter >= inf_data->syscalls_counts.size ())
 108             inf_data->syscalls_counts.resize (iter + 1);
 109           ++inf_data->syscalls_counts[iter];
 110         }
 111     }
 112
 113   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 114                                         inf_data->total_syscalls_count != 0,
 115                                         inf_data->any_syscall_count,
 116                                         inf_data->syscalls_counts);
 117 }
 118
 119 /* Implement the "remove" breakpoint_ops method for syscall
 120    catchpoints.  */
 121
 122 static int
 123 remove_catch_syscall (struct bp_location *bl, enum remove_bp_reason reason)
 124 {
 125   struct syscall_catchpoint *c = (struct syscall_catchpoint *) bl->owner;
 126   struct inferior *inf = current_inferior ();
 127   struct catch_syscall_inferior_data *inf_data
 128     = get_catch_syscall_inferior_data (inf);
 129
 130   --inf_data->total_syscalls_count;
 131   if (c->syscalls_to_be_caught.empty ())
 132     --inf_data->any_syscall_count;
 133   else
 134     {
 135       for (int iter : c->syscalls_to_be_caught)
 136         {
 137           if (iter >= inf_data->syscalls_counts.size ())
 138             /* Shouldn't happen.  */
 139             continue;
 140           --inf_data->syscalls_counts[iter];
 141         }
 142     }
 143
 144   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 145                                         inf_data->total_syscalls_count != 0,
 146                                         inf_data->any_syscall_count,
 147                                         inf_data->syscalls_counts);
 148 }
 149
 150 /* Implement the "breakpoint_hit" breakpoint_ops method for syscall
 151    catchpoints.  */
 152
 153 static int
 154 breakpoint_hit_catch_syscall (const struct bp_location *bl,
 155                               const address_space *aspace, CORE_ADDR bp_addr,
 156                               const struct target_waitstatus *ws)
 157 {
 158   /* We must check if we are catching specific syscalls in this
 159      breakpoint.  If we are, then we must guarantee that the called
 160      syscall is the same syscall we are catching.  */
 161   int syscall_number = 0;
 162   const struct syscall_catchpoint *c
 163     = (const struct syscall_catchpoint *) bl->owner;
 164
 165   if (ws->kind != TARGET_WAITKIND_SYSCALL_ENTRY
 166       && ws->kind != TARGET_WAITKIND_SYSCALL_RETURN)
 167     return 0;
 168
 169   syscall_number = ws->value.syscall_number;
 170
 171   /* Now, checking if the syscall is the same.  */
 172   if (!c->syscalls_to_be_caught.empty ())
 173     {
 174       for (int iter : c->syscalls_to_be_caught)
 175         if (syscall_number == iter)
 176           return 1;
 177
 178       return 0;
 179     }
 180
 181   return 1;
 182 }
 183
 184 /* Implement the "print_it" breakpoint_ops method for syscall
 185    catchpoints.  */
 186
 187 static enum print_stop_action
 188 print_it_catch_syscall (bpstat bs)
 189 {
 190   struct ui_out *uiout = current_uiout;
 191   struct breakpoint *b = bs->breakpoint_at;
 192   /* These are needed because we want to know in which state a
 193      syscall is.  It can be in the TARGET_WAITKIND_SYSCALL_ENTRY
 194      or TARGET_WAITKIND_SYSCALL_RETURN, and depending on it we
 195      must print "called syscall" or "returned from syscall".  */
 196   ptid_t ptid;
 197   struct target_waitstatus last;
 198   struct syscall s;
 199   struct gdbarch *gdbarch = bs->bp_location_at->gdbarch;
 200
 201   get_last_target_status (&ptid, &last);
 202
 203   get_syscall_by_number (gdbarch, last.value.syscall_number, &s);
 204
 205   annotate_catchpoint (b->number);
 206   maybe_print_thread_hit_breakpoint (uiout);
 207
 208   if (b->disposition == disp_del)
 209     uiout->text ("Temporary catchpoint ");
 210   else
 211     uiout->text ("Catchpoint ");
 212   if (uiout->is_mi_like_p ())
 213     {
 214       uiout->field_string ("reason",
 215                            async_reason_lookup (last.kind == TARGET_WAITKIND_SYSCALL_ENTRY
 216                                                 ? EXEC_ASYNC_SYSCALL_ENTRY
 217                                                 : EXEC_ASYNC_SYSCALL_RETURN));
 218       uiout->field_string ("disp", bpdisp_text (b->disposition));
 219     }
 220   uiout->field_int ("bkptno", b->number);
 221
 222   if (last.kind == TARGET_WAITKIND_SYSCALL_ENTRY)
 223     uiout->text (" (call to syscall ");
 224   else
 225     uiout->text (" (returned from syscall ");
 226
 227   if (s.name == NULL || uiout->is_mi_like_p ())
 228     uiout->field_int ("syscall-number", last.value.syscall_number);
 229   if (s.name != NULL)
 230     uiout->field_string ("syscall-name", s.name);
 231
 232   uiout->text ("), ");
 233
 234   return PRINT_SRC_AND_LOC;
 235 }
 236
 237 /* Implement the "print_one" breakpoint_ops method for syscall
 238    catchpoints.  */
 239
 240 static void
 241 print_one_catch_syscall (struct breakpoint *b,
 242                          struct bp_location **last_loc)
 243 {
 244   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 245   struct value_print_options opts;
 246   struct ui_out *uiout = current_uiout;
 247   struct gdbarch *gdbarch = b->loc->gdbarch;
 248
 249   get_user_print_options (&opts);
 250   /* Field 4, the address, is omitted (which makes the columns not
 251      line up too nicely with the headers, but the effect is relatively
 252      readable).  */
 253   if (opts.addressprint)
 254     uiout->field_skip ("addr");
 255   annotate_field (5);
 256
 257   if (c->syscalls_to_be_caught.size () > 1)
 258     uiout->text ("syscalls \"");
 259   else
 260     uiout->text ("syscall \"");
 261
 262   if (!c->syscalls_to_be_caught.empty ())
 263     {
 264       char *text = xstrprintf ("%s", "");
 265
 266       for (int iter : c->syscalls_to_be_caught)
 267         {
 268           char *x = text;
 269           struct syscall s;
 270           get_syscall_by_number (gdbarch, iter, &s);
 271
 272           if (s.name != NULL)
 273             text = xstrprintf ("%s%s, ", text, s.name);
 274           else
 275             text = xstrprintf ("%s%d, ", text, iter);
 276
 277           /* We have to xfree the last 'text' (now stored at 'x')
 278              because xstrprintf dynamically allocates new space for it
 279              on every call.  */
 280           xfree (x);
 281         }
 282       /* Remove the last comma.  */
 283       text[strlen (text) - 2] = '\0';
 284       uiout->field_string ("what", text);
 285     }
 286   else
 287     uiout->field_string ("what", "<any syscall>");
 288   uiout->text ("\" ");
 289
 290   if (uiout->is_mi_like_p ())
 291     uiout->field_string ("catch-type", "syscall");
 292 }
 293
 294 /* Implement the "print_mention" breakpoint_ops method for syscall
 295    catchpoints.  */
 296
 297 static void
 298 print_mention_catch_syscall (struct breakpoint *b)
 299 {
 300   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 301   struct gdbarch *gdbarch = b->loc->gdbarch;
 302
 303   if (!c->syscalls_to_be_caught.empty ())
 304     {
 305       if (c->syscalls_to_be_caught.size () > 1)
 306         printf_filtered (_("Catchpoint %d (syscalls"), b->number);
 307       else
 308         printf_filtered (_("Catchpoint %d (syscall"), b->number);
 309
 310       for (int iter : c->syscalls_to_be_caught)
 311         {
 312           struct syscall s;
 313           get_syscall_by_number (gdbarch, iter, &s);
 314
 315           if (s.name != NULL)
 316             printf_filtered (" '%s' [%d]", s.name, s.number);
 317           else
 318             printf_filtered (" %d", s.number);
 319         }
 320       printf_filtered (")");
 321     }
 322   else
 323     printf_filtered (_("Catchpoint %d (any syscall)"),
 324                      b->number);
 325 }
 326
 327 /* Implement the "print_recreate" breakpoint_ops method for syscall
 328    catchpoints.  */
 329
 330 static void
 331 print_recreate_catch_syscall (struct breakpoint *b, struct ui_file *fp)
 332 {
 333   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 334   struct gdbarch *gdbarch = b->loc->gdbarch;
 335
 336   fprintf_unfiltered (fp, "catch syscall");
 337
 338   for (int iter : c->syscalls_to_be_caught)
 339     {
 340       struct syscall s;
 341
 342       get_syscall_by_number (gdbarch, iter, &s);
 343       if (s.name != NULL)
 344         fprintf_unfiltered (fp, " %s", s.name);
 345       else
 346         fprintf_unfiltered (fp, " %d", s.number);
 347     }
 348
 349   print_recreate_thread (b, fp);
 350 }
 351
 352 /* The breakpoint_ops structure to be used in syscall catchpoints.  */
 353
 354 static struct breakpoint_ops catch_syscall_breakpoint_ops;
 355
 356 /* Returns non-zero if 'b' is a syscall catchpoint.  */
 357
 358 static int
 359 syscall_catchpoint_p (struct breakpoint *b)
 360 {
 361   return (b->ops == &catch_syscall_breakpoint_ops);
 362 }
 363
 364 static void
 365 create_syscall_event_catchpoint (int tempflag, std::vector<int> &&filter,
 366                                  const struct breakpoint_ops *ops)
 367 {
 368   struct gdbarch *gdbarch = get_current_arch ();
 369
 370   std::unique_ptr<syscall_catchpoint> c (new syscall_catchpoint ());
 371   init_catchpoint (c.get (), gdbarch, tempflag, NULL, ops);
 372   c->syscalls_to_be_caught = std::move (filter);
 373
 374   install_breakpoint (0, std::move (c), 1);
 375 }
 376
 377 /* Splits the argument using space as delimiter.  */
 378
 379 static std::vector<int>
 380 catch_syscall_split_args (const char *arg)
 381 {
 382   std::vector<int> result;
 383   struct gdbarch *gdbarch = target_gdbarch ();
 384
 385   while (*arg != '\0')
 386     {
 387       int i, syscall_number;
 388       char *endptr;
 389       char cur_name[128];
 390       struct syscall s;
 391
 392       /* Skip whitespace.  */
 393       arg = skip_spaces (arg);
 394
 395       for (i = 0; i < 127 && arg[i] && !isspace (arg[i]); ++i)
 396         cur_name[i] = arg[i];
 397       cur_name[i] = '\0';
 398       arg += i;
 399
 400       /* Check if the user provided a syscall name, group, or a number.  */
 401       syscall_number = (int) strtol (cur_name, &endptr, 0);
 402       if (*endptr == '\0')
 403         {
 404           get_syscall_by_number (gdbarch, syscall_number, &s);
 405           result.push_back (s.number);
 406         }
 407       else if (startswith (cur_name, "g:")
 408                || startswith (cur_name, "group:"))
 409         {
 410           /* We have a syscall group.  Let's expand it into a syscall
 411              list before inserting.  */
 412           const char *group_name;
 413
 414           /* Skip over "g:" and "group:" prefix strings.  */
 415           group_name = strchr (cur_name, ':') + 1;
 416
 417           if (!get_syscalls_by_group (gdbarch, group_name, &result))
 418             error (_("Unknown syscall group '%s'."), group_name);
 419         }
 420       else
 421         {
 422           /* We have a name.  Let's check if it's valid and fetch a
 423              list of matching numbers.  */
 424           if (!get_syscalls_by_name (gdbarch, cur_name, &result))
 425             /* Here we have to issue an error instead of a warning,
 426                because GDB cannot do anything useful if there's no
 427                syscall number to be caught.  */
 428             error (_("Unknown syscall name '%s'."), cur_name);
 429         }
 430     }
 431
 432   return result;
 433 }
 434
 435 /* Implement the "catch syscall" command.  */
 436
 437 static void
 438 catch_syscall_command_1 (const char *arg, int from_tty,
 439                          struct cmd_list_element *command)
 440 {
 441   int tempflag;
 442   std::vector<int> filter;
 443   struct syscall s;
 444   struct gdbarch *gdbarch = get_current_arch ();
 445
 446   /* Checking if the feature if supported.  */
 447   if (gdbarch_get_syscall_number_p (gdbarch) == 0)
 448     error (_("The feature 'catch syscall' is not supported on \
 449 this architecture yet."));
 450
 451   tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 452
 453   arg = skip_spaces (arg);
 454
 455   /* We need to do this first "dummy" translation in order
 456      to get the syscall XML file loaded or, most important,
 457      to display a warning to the user if there's no XML file
 458      for his/her architecture.  */
 459   get_syscall_by_number (gdbarch, 0, &s);
 460
 461   /* The allowed syntax is:
 462      catch syscall
 463      catch syscall <name | number> [<name | number> ... <name | number>]
 464
 465      Let's check if there's a syscall name.  */
 466
 467   if (arg != NULL)
 468     filter = catch_syscall_split_args (arg);
 469
 470   create_syscall_event_catchpoint (tempflag, std::move (filter),
 471                                    &catch_syscall_breakpoint_ops);
 472 }
 473
 474
 475 /* Returns 0 if 'bp' is NOT a syscall catchpoint,
 476    non-zero otherwise.  */
 477 static int
 478 is_syscall_catchpoint_enabled (struct breakpoint *bp)
 479 {
 480   if (syscall_catchpoint_p (bp)
 481       && bp->enable_state != bp_disabled
 482       && bp->enable_state != bp_call_disabled)
 483     return 1;
 484   else
 485     return 0;
 486 }
 487
 488 int
 489 catch_syscall_enabled (void)
 490 {
 491   struct catch_syscall_inferior_data *inf_data
 492     = get_catch_syscall_inferior_data (current_inferior ());
 493
 494   return inf_data->total_syscalls_count != 0;
 495 }
 496
 497 /* Helper function for catching_syscall_number.  If B is a syscall
 498    catchpoint for SYSCALL_NUMBER, return 1 (which will make
 499    'breakpoint_find_if' return).  Otherwise, return 0.  */
 500
 501 static int
 502 catching_syscall_number_1 (struct breakpoint *b,
 503                            void *data)
 504 {
 505   int syscall_number = (int) (uintptr_t) data;
 506
 507   if (is_syscall_catchpoint_enabled (b))
 508     {
 509       struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 510
 511       if (!c->syscalls_to_be_caught.empty ())
 512         {
 513           for (int iter : c->syscalls_to_be_caught)
 514             if (syscall_number == iter)
 515               return 1;
 516         }
 517       else
 518         return 1;
 519     }
 520
 521   return 0;
 522 }
 523
 524 int
 525 catching_syscall_number (int syscall_number)
 526 {
 527   struct breakpoint *b = breakpoint_find_if (catching_syscall_number_1,
 528                                          (void *) (uintptr_t) syscall_number);
 529
 530   return b != NULL;
 531 }
 532
 533 /* Complete syscall names.  Used by "catch syscall".  */
 534
 535 static void
 536 catch_syscall_completer (struct cmd_list_element *cmd,
 537                          completion_tracker &tracker,
 538                          const char *text, const char *word)
 539 {
 540   struct gdbarch *gdbarch = get_current_arch ();
 541   gdb::unique_xmalloc_ptr<const char *> group_list;
 542   const char *prefix;
 543
 544   /* Completion considers ':' to be a word separator, so we use this to
 545      verify whether the previous word was a group prefix.  If so, we
 546      build the completion list using group names only.  */
 547   for (prefix = word; prefix != text && prefix[-1] != ' '; prefix--)
 548     ;
 549
 550   if (startswith (prefix, "g:") || startswith (prefix, "group:"))
 551     {
 552       /* Perform completion inside 'group:' namespace only.  */
 553       group_list.reset (get_syscall_group_names (gdbarch));
 554       if (group_list != NULL)
 555         complete_on_enum (tracker, group_list.get (), word, word);
 556     }
 557   else
 558     {
 559       /* Complete with both, syscall names and groups.  */
 560       gdb::unique_xmalloc_ptr<const char *> syscall_list
 561         (get_syscall_names (gdbarch));
 562       group_list.reset (get_syscall_group_names (gdbarch));
 563
 564       const char **group_ptr = group_list.get ();
 565
 566       /* Hold on to strings while we're using them.  */
 567       std::vector<std::string> holders;
 568
 569       /* Append "group:" prefix to syscall groups.  */
 570       for (int i = 0; group_ptr[i] != NULL; i++)
 571         holders.push_back (string_printf ("group:%s", group_ptr[i]));
 572
 573       for (int i = 0; group_ptr[i] != NULL; i++)
 574         group_ptr[i] = holders[i].c_str ();
 575
 576       if (syscall_list != NULL)
 577         complete_on_enum (tracker, syscall_list.get (), word, word);
 578       if (group_list != NULL)
 579         complete_on_enum (tracker, group_ptr, word, word);
 580     }
 581 }
 582
 583 static void
 584 clear_syscall_counts (struct inferior *inf)
 585 {
 586   struct catch_syscall_inferior_data *inf_data
 587     = get_catch_syscall_inferior_data (inf);
 588
 589   inf_data->total_syscalls_count = 0;
 590   inf_data->any_syscall_count = 0;
 591   inf_data->syscalls_counts.clear ();
 592 }
 593
 594 static void
 595 initialize_syscall_catchpoint_ops (void)
 596 {
 597   struct breakpoint_ops *ops;
 598
 599   initialize_breakpoint_ops ();
 600
 601   /* Syscall catchpoints.  */
 602   ops = &catch_syscall_breakpoint_ops;
 603   *ops = base_breakpoint_ops;
 604   ops->insert_location = insert_catch_syscall;
 605   ops->remove_location = remove_catch_syscall;
 606   ops->breakpoint_hit = breakpoint_hit_catch_syscall;
 607   ops->print_it = print_it_catch_syscall;
 608   ops->print_one = print_one_catch_syscall;
 609   ops->print_mention = print_mention_catch_syscall;
 610   ops->print_recreate = print_recreate_catch_syscall;
 611 }
 612
 613 void
 614 _initialize_break_catch_syscall (void)
 615 {
 616   initialize_syscall_catchpoint_ops ();
 617
 618   gdb::observers::inferior_exit.attach (clear_syscall_counts);
 619   catch_syscall_inferior_data
 620     = register_inferior_data_with_cleanup (NULL,
 621                                            catch_syscall_inferior_data_cleanup);
 622
 623   add_catch_command ("syscall", _("\
 624 Catch system calls by their names, groups and/or numbers.\n\
 625 Arguments say which system calls to catch.  If no arguments are given,\n\
 626 every system call will be caught.  Arguments, if given, should be one\n\
 627 or more system call names (if your system supports that), system call\n\
 628 groups or system call numbers."),
 629                      catch_syscall_command_1,
 630                      catch_syscall_completer,
 631                      CATCH_PERMANENT,
 632                      CATCH_TEMPORARY);
 633 }