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 convert it
 423              to a number.  */
 424           get_syscall_by_name (gdbarch, cur_name, &s);
 425
 426           if (s.number == UNKNOWN_SYSCALL)
 427             /* Here we have to issue an error instead of a warning,
 428                because GDB cannot do anything useful if there's no
 429                syscall number to be caught.  */
 430             error (_("Unknown syscall name '%s'."), cur_name);
 431
 432           /* Ok, it's valid.  */
 433           result.push_back (s.number);
 434         }
 435     }
 436
 437   return result;
 438 }
 439
 440 /* Implement the "catch syscall" command.  */
 441
 442 static void
 443 catch_syscall_command_1 (const char *arg, int from_tty,
 444                          struct cmd_list_element *command)
 445 {
 446   int tempflag;
 447   std::vector<int> filter;
 448   struct syscall s;
 449   struct gdbarch *gdbarch = get_current_arch ();
 450
 451   /* Checking if the feature if supported.  */
 452   if (gdbarch_get_syscall_number_p (gdbarch) == 0)
 453     error (_("The feature 'catch syscall' is not supported on \
 454 this architecture yet."));
 455
 456   tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 457
 458   arg = skip_spaces (arg);
 459
 460   /* We need to do this first "dummy" translation in order
 461      to get the syscall XML file loaded or, most important,
 462      to display a warning to the user if there's no XML file
 463      for his/her architecture.  */
 464   get_syscall_by_number (gdbarch, 0, &s);
 465
 466   /* The allowed syntax is:
 467      catch syscall
 468      catch syscall <name | number> [<name | number> ... <name | number>]
 469
 470      Let's check if there's a syscall name.  */
 471
 472   if (arg != NULL)
 473     filter = catch_syscall_split_args (arg);
 474
 475   create_syscall_event_catchpoint (tempflag, std::move (filter),
 476                                    &catch_syscall_breakpoint_ops);
 477 }
 478
 479
 480 /* Returns 0 if 'bp' is NOT a syscall catchpoint,
 481    non-zero otherwise.  */
 482 static int
 483 is_syscall_catchpoint_enabled (struct breakpoint *bp)
 484 {
 485   if (syscall_catchpoint_p (bp)
 486       && bp->enable_state != bp_disabled
 487       && bp->enable_state != bp_call_disabled)
 488     return 1;
 489   else
 490     return 0;
 491 }
 492
 493 int
 494 catch_syscall_enabled (void)
 495 {
 496   struct catch_syscall_inferior_data *inf_data
 497     = get_catch_syscall_inferior_data (current_inferior ());
 498
 499   return inf_data->total_syscalls_count != 0;
 500 }
 501
 502 /* Helper function for catching_syscall_number.  If B is a syscall
 503    catchpoint for SYSCALL_NUMBER, return 1 (which will make
 504    'breakpoint_find_if' return).  Otherwise, return 0.  */
 505
 506 static int
 507 catching_syscall_number_1 (struct breakpoint *b,
 508                            void *data)
 509 {
 510   int syscall_number = (int) (uintptr_t) data;
 511
 512   if (is_syscall_catchpoint_enabled (b))
 513     {
 514       struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 515
 516       if (!c->syscalls_to_be_caught.empty ())
 517         {
 518           for (int iter : c->syscalls_to_be_caught)
 519             if (syscall_number == iter)
 520               return 1;
 521         }
 522       else
 523         return 1;
 524     }
 525
 526   return 0;
 527 }
 528
 529 int
 530 catching_syscall_number (int syscall_number)
 531 {
 532   struct breakpoint *b = breakpoint_find_if (catching_syscall_number_1,
 533                                          (void *) (uintptr_t) syscall_number);
 534
 535   return b != NULL;
 536 }
 537
 538 /* Complete syscall names.  Used by "catch syscall".  */
 539
 540 static void
 541 catch_syscall_completer (struct cmd_list_element *cmd,
 542                          completion_tracker &tracker,
 543                          const char *text, const char *word)
 544 {
 545   struct gdbarch *gdbarch = get_current_arch ();
 546   gdb::unique_xmalloc_ptr<const char *> group_list;
 547   const char *prefix;
 548
 549   /* Completion considers ':' to be a word separator, so we use this to
 550      verify whether the previous word was a group prefix.  If so, we
 551      build the completion list using group names only.  */
 552   for (prefix = word; prefix != text && prefix[-1] != ' '; prefix--)
 553     ;
 554
 555   if (startswith (prefix, "g:") || startswith (prefix, "group:"))
 556     {
 557       /* Perform completion inside 'group:' namespace only.  */
 558       group_list.reset (get_syscall_group_names (gdbarch));
 559       if (group_list != NULL)
 560         complete_on_enum (tracker, group_list.get (), word, word);
 561     }
 562   else
 563     {
 564       /* Complete with both, syscall names and groups.  */
 565       gdb::unique_xmalloc_ptr<const char *> syscall_list
 566         (get_syscall_names (gdbarch));
 567       group_list.reset (get_syscall_group_names (gdbarch));
 568
 569       const char **group_ptr = group_list.get ();
 570
 571       /* Hold on to strings while we're using them.  */
 572       std::vector<std::string> holders;
 573
 574       /* Append "group:" prefix to syscall groups.  */
 575       for (int i = 0; group_ptr[i] != NULL; i++)
 576         holders.push_back (string_printf ("group:%s", group_ptr[i]));
 577
 578       for (int i = 0; group_ptr[i] != NULL; i++)
 579         group_ptr[i] = holders[i].c_str ();
 580
 581       if (syscall_list != NULL)
 582         complete_on_enum (tracker, syscall_list.get (), word, word);
 583       if (group_list != NULL)
 584         complete_on_enum (tracker, group_ptr, word, word);
 585     }
 586 }
 587
 588 static void
 589 clear_syscall_counts (struct inferior *inf)
 590 {
 591   struct catch_syscall_inferior_data *inf_data
 592     = get_catch_syscall_inferior_data (inf);
 593
 594   inf_data->total_syscalls_count = 0;
 595   inf_data->any_syscall_count = 0;
 596   inf_data->syscalls_counts.clear ();
 597 }
 598
 599 static void
 600 initialize_syscall_catchpoint_ops (void)
 601 {
 602   struct breakpoint_ops *ops;
 603
 604   initialize_breakpoint_ops ();
 605
 606   /* Syscall catchpoints.  */
 607   ops = &catch_syscall_breakpoint_ops;
 608   *ops = base_breakpoint_ops;
 609   ops->insert_location = insert_catch_syscall;
 610   ops->remove_location = remove_catch_syscall;
 611   ops->breakpoint_hit = breakpoint_hit_catch_syscall;
 612   ops->print_it = print_it_catch_syscall;
 613   ops->print_one = print_one_catch_syscall;
 614   ops->print_mention = print_mention_catch_syscall;
 615   ops->print_recreate = print_recreate_catch_syscall;
 616 }
 617
 618 void
 619 _initialize_break_catch_syscall (void)
 620 {
 621   initialize_syscall_catchpoint_ops ();
 622
 623   gdb::observers::inferior_exit.attach (clear_syscall_counts);
 624   catch_syscall_inferior_data
 625     = register_inferior_data_with_cleanup (NULL,
 626                                            catch_syscall_inferior_data_cleanup);
 627
 628   add_catch_command ("syscall", _("\
 629 Catch system calls by their names, groups and/or numbers.\n\
 630 Arguments say which system calls to catch.  If no arguments are given,\n\
 631 every system call will be caught.  Arguments, if given, should be one\n\
 632 or more system call names (if your system supports that), system call\n\
 633 groups or system call numbers."),
 634                      catch_syscall_command_1,
 635                      catch_syscall_completer,
 636                      CATCH_PERMANENT,
 637                      CATCH_TEMPORARY);
 638 }