gdb/break-catch-syscall.c

   1 /* Everything about syscall catchpoints, for GDB.
   2
   3    Copyright (C) 2009-2020 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 #include "cli/cli-style.h"
  33
  34 /* An instance of this type is used to represent a syscall catchpoint.
  35    A breakpoint is really of this type iff its ops pointer points to
  36    CATCH_SYSCALL_BREAKPOINT_OPS.  */
  37
  38 struct syscall_catchpoint : public breakpoint
  39 {
  40   /* Syscall numbers used for the 'catch syscall' feature.  If no
  41      syscall has been specified for filtering, it is empty.
  42      Otherwise, it holds a list of all syscalls to be caught.  */
  43   std::vector<int> syscalls_to_be_caught;
  44 };
  45
  46 struct catch_syscall_inferior_data
  47 {
  48   /* We keep a count of the number of times the user has requested a
  49      particular syscall to be tracked, and pass this information to the
  50      target.  This lets capable targets implement filtering directly.  */
  51
  52   /* Number of times that "any" syscall is requested.  */
  53   int any_syscall_count;
  54
  55   /* Count of each system call.  */
  56   std::vector<int> syscalls_counts;
  57
  58   /* This counts all syscall catch requests, so we can readily determine
  59      if any catching is necessary.  */
  60   int total_syscalls_count;
  61 };
  62
  63 static const struct inferior_key<struct catch_syscall_inferior_data>
  64   catch_syscall_inferior_data;
  65
  66 static struct catch_syscall_inferior_data *
  67 get_catch_syscall_inferior_data (struct inferior *inf)
  68 {
  69   struct catch_syscall_inferior_data *inf_data;
  70
  71   inf_data = catch_syscall_inferior_data.get (inf);
  72   if (inf_data == NULL)
  73     inf_data = catch_syscall_inferior_data.emplace (inf);
  74
  75   return inf_data;
  76 }
  77
  78 /* Implement the "insert" breakpoint_ops method for syscall
  79    catchpoints.  */
  80
  81 static int
  82 insert_catch_syscall (struct bp_location *bl)
  83 {
  84   struct syscall_catchpoint *c = (struct syscall_catchpoint *) bl->owner;
  85   struct inferior *inf = current_inferior ();
  86   struct catch_syscall_inferior_data *inf_data
  87     = get_catch_syscall_inferior_data (inf);
  88
  89   ++inf_data->total_syscalls_count;
  90   if (c->syscalls_to_be_caught.empty ())
  91     ++inf_data->any_syscall_count;
  92   else
  93     {
  94       for (int iter : c->syscalls_to_be_caught)
  95         {
  96           if (iter >= inf_data->syscalls_counts.size ())
  97             inf_data->syscalls_counts.resize (iter + 1);
  98           ++inf_data->syscalls_counts[iter];
  99         }
 100     }
 101
 102   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 103                                         inf_data->total_syscalls_count != 0,
 104                                         inf_data->any_syscall_count,
 105                                         inf_data->syscalls_counts);
 106 }
 107
 108 /* Implement the "remove" breakpoint_ops method for syscall
 109    catchpoints.  */
 110
 111 static int
 112 remove_catch_syscall (struct bp_location *bl, enum remove_bp_reason reason)
 113 {
 114   struct syscall_catchpoint *c = (struct syscall_catchpoint *) bl->owner;
 115   struct inferior *inf = current_inferior ();
 116   struct catch_syscall_inferior_data *inf_data
 117     = get_catch_syscall_inferior_data (inf);
 118
 119   --inf_data->total_syscalls_count;
 120   if (c->syscalls_to_be_caught.empty ())
 121     --inf_data->any_syscall_count;
 122   else
 123     {
 124       for (int iter : c->syscalls_to_be_caught)
 125         {
 126           if (iter >= inf_data->syscalls_counts.size ())
 127             /* Shouldn't happen.  */
 128             continue;
 129           --inf_data->syscalls_counts[iter];
 130         }
 131     }
 132
 133   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 134                                         inf_data->total_syscalls_count != 0,
 135                                         inf_data->any_syscall_count,
 136                                         inf_data->syscalls_counts);
 137 }
 138
 139 /* Implement the "breakpoint_hit" breakpoint_ops method for syscall
 140    catchpoints.  */
 141
 142 static int
 143 breakpoint_hit_catch_syscall (const struct bp_location *bl,
 144                               const address_space *aspace, CORE_ADDR bp_addr,
 145                               const struct target_waitstatus *ws)
 146 {
 147   /* We must check if we are catching specific syscalls in this
 148      breakpoint.  If we are, then we must guarantee that the called
 149      syscall is the same syscall we are catching.  */
 150   int syscall_number = 0;
 151   const struct syscall_catchpoint *c
 152     = (const struct syscall_catchpoint *) bl->owner;
 153
 154   if (ws->kind != TARGET_WAITKIND_SYSCALL_ENTRY
 155       && ws->kind != TARGET_WAITKIND_SYSCALL_RETURN)
 156     return 0;
 157
 158   syscall_number = ws->value.syscall_number;
 159
 160   /* Now, checking if the syscall is the same.  */
 161   if (!c->syscalls_to_be_caught.empty ())
 162     {
 163       for (int iter : c->syscalls_to_be_caught)
 164         if (syscall_number == iter)
 165           return 1;
 166
 167       return 0;
 168     }
 169
 170   return 1;
 171 }
 172
 173 /* Implement the "print_it" breakpoint_ops method for syscall
 174    catchpoints.  */
 175
 176 static enum print_stop_action
 177 print_it_catch_syscall (bpstat bs)
 178 {
 179   struct ui_out *uiout = current_uiout;
 180   struct breakpoint *b = bs->breakpoint_at;
 181   /* These are needed because we want to know in which state a
 182      syscall is.  It can be in the TARGET_WAITKIND_SYSCALL_ENTRY
 183      or TARGET_WAITKIND_SYSCALL_RETURN, and depending on it we
 184      must print "called syscall" or "returned from syscall".  */
 185   struct target_waitstatus last;
 186   struct syscall s;
 187   struct gdbarch *gdbarch = bs->bp_location_at->gdbarch;
 188
 189   get_last_target_status (nullptr, &last);
 190
 191   get_syscall_by_number (gdbarch, last.value.syscall_number, &s);
 192
 193   annotate_catchpoint (b->number);
 194   maybe_print_thread_hit_breakpoint (uiout);
 195
 196   if (b->disposition == disp_del)
 197     uiout->text ("Temporary catchpoint ");
 198   else
 199     uiout->text ("Catchpoint ");
 200   if (uiout->is_mi_like_p ())
 201     {
 202       uiout->field_string ("reason",
 203                            async_reason_lookup (last.kind == TARGET_WAITKIND_SYSCALL_ENTRY
 204                                                 ? EXEC_ASYNC_SYSCALL_ENTRY
 205                                                 : EXEC_ASYNC_SYSCALL_RETURN));
 206       uiout->field_string ("disp", bpdisp_text (b->disposition));
 207     }
 208   uiout->field_signed ("bkptno", b->number);
 209
 210   if (last.kind == TARGET_WAITKIND_SYSCALL_ENTRY)
 211     uiout->text (" (call to syscall ");
 212   else
 213     uiout->text (" (returned from syscall ");
 214
 215   if (s.name == NULL || uiout->is_mi_like_p ())
 216     uiout->field_signed ("syscall-number", last.value.syscall_number);
 217   if (s.name != NULL)
 218     uiout->field_string ("syscall-name", s.name);
 219
 220   uiout->text ("), ");
 221
 222   return PRINT_SRC_AND_LOC;
 223 }
 224
 225 /* Implement the "print_one" breakpoint_ops method for syscall
 226    catchpoints.  */
 227
 228 static void
 229 print_one_catch_syscall (struct breakpoint *b,
 230                          struct bp_location **last_loc)
 231 {
 232   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 233   struct value_print_options opts;
 234   struct ui_out *uiout = current_uiout;
 235   struct gdbarch *gdbarch = b->loc->gdbarch;
 236
 237   get_user_print_options (&opts);
 238   /* Field 4, the address, is omitted (which makes the columns not
 239      line up too nicely with the headers, but the effect is relatively
 240      readable).  */
 241   if (opts.addressprint)
 242     uiout->field_skip ("addr");
 243   annotate_field (5);
 244
 245   if (c->syscalls_to_be_caught.size () > 1)
 246     uiout->text ("syscalls \"");
 247   else
 248     uiout->text ("syscall \"");
 249
 250   if (!c->syscalls_to_be_caught.empty ())
 251     {
 252       char *text = xstrprintf ("%s", "");
 253
 254       for (int iter : c->syscalls_to_be_caught)
 255         {
 256           char *previous_text = text;
 257           struct syscall s;
 258           get_syscall_by_number (gdbarch, iter, &s);
 259
 260           if (s.name != NULL)
 261             text = xstrprintf ("%s%s, ", text, s.name);
 262           else
 263             text = xstrprintf ("%s%d, ", text, iter);
 264
 265           /* We have to xfree previous_text because xstrprintf dynamically
 266              allocates new space for text on every call.  */
 267           xfree (previous_text);
 268         }
 269       /* Remove the last comma.  */
 270       text[strlen (text) - 2] = '\0';
 271       uiout->field_string ("what", text);
 272       /* xfree last text.  */
 273       xfree (text);
 274     }
 275   else
 276     uiout->field_string ("what", "<any syscall>", metadata_style.style ());
 277   uiout->text ("\" ");
 278
 279   if (uiout->is_mi_like_p ())
 280     uiout->field_string ("catch-type", "syscall");
 281 }
 282
 283 /* Implement the "print_mention" breakpoint_ops method for syscall
 284    catchpoints.  */
 285
 286 static void
 287 print_mention_catch_syscall (struct breakpoint *b)
 288 {
 289   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 290   struct gdbarch *gdbarch = b->loc->gdbarch;
 291
 292   if (!c->syscalls_to_be_caught.empty ())
 293     {
 294       if (c->syscalls_to_be_caught.size () > 1)
 295         printf_filtered (_("Catchpoint %d (syscalls"), b->number);
 296       else
 297         printf_filtered (_("Catchpoint %d (syscall"), b->number);
 298
 299       for (int iter : c->syscalls_to_be_caught)
 300         {
 301           struct syscall s;
 302           get_syscall_by_number (gdbarch, iter, &s);
 303
 304           if (s.name != NULL)
 305             printf_filtered (" '%s' [%d]", s.name, s.number);
 306           else
 307             printf_filtered (" %d", s.number);
 308         }
 309       printf_filtered (")");
 310     }
 311   else
 312     printf_filtered (_("Catchpoint %d (any syscall)"),
 313                      b->number);
 314 }
 315
 316 /* Implement the "print_recreate" breakpoint_ops method for syscall
 317    catchpoints.  */
 318
 319 static void
 320 print_recreate_catch_syscall (struct breakpoint *b, struct ui_file *fp)
 321 {
 322   struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 323   struct gdbarch *gdbarch = b->loc->gdbarch;
 324
 325   fprintf_unfiltered (fp, "catch syscall");
 326
 327   for (int iter : c->syscalls_to_be_caught)
 328     {
 329       struct syscall s;
 330
 331       get_syscall_by_number (gdbarch, iter, &s);
 332       if (s.name != NULL)
 333         fprintf_unfiltered (fp, " %s", s.name);
 334       else
 335         fprintf_unfiltered (fp, " %d", s.number);
 336     }
 337
 338   print_recreate_thread (b, fp);
 339 }
 340
 341 /* The breakpoint_ops structure to be used in syscall catchpoints.  */
 342
 343 static struct breakpoint_ops catch_syscall_breakpoint_ops;
 344
 345 /* Returns non-zero if 'b' is a syscall catchpoint.  */
 346
 347 static int
 348 syscall_catchpoint_p (struct breakpoint *b)
 349 {
 350   return (b->ops == &catch_syscall_breakpoint_ops);
 351 }
 352
 353 static void
 354 create_syscall_event_catchpoint (int tempflag, std::vector<int> &&filter,
 355                                  const struct breakpoint_ops *ops)
 356 {
 357   struct gdbarch *gdbarch = get_current_arch ();
 358
 359   std::unique_ptr<syscall_catchpoint> c (new syscall_catchpoint ());
 360   init_catchpoint (c.get (), gdbarch, tempflag, NULL, ops);
 361   c->syscalls_to_be_caught = std::move (filter);
 362
 363   install_breakpoint (0, std::move (c), 1);
 364 }
 365
 366 /* Splits the argument using space as delimiter.  */
 367
 368 static std::vector<int>
 369 catch_syscall_split_args (const char *arg)
 370 {
 371   std::vector<int> result;
 372   struct gdbarch *gdbarch = target_gdbarch ();
 373
 374   while (*arg != '\0')
 375     {
 376       int i, syscall_number;
 377       char *endptr;
 378       char cur_name[128];
 379       struct syscall s;
 380
 381       /* Skip whitespace.  */
 382       arg = skip_spaces (arg);
 383
 384       for (i = 0; i < 127 && arg[i] && !isspace (arg[i]); ++i)
 385         cur_name[i] = arg[i];
 386       cur_name[i] = '\0';
 387       arg += i;
 388
 389       /* Check if the user provided a syscall name, group, or a number.  */
 390       syscall_number = (int) strtol (cur_name, &endptr, 0);
 391       if (*endptr == '\0')
 392         {
 393           get_syscall_by_number (gdbarch, syscall_number, &s);
 394           result.push_back (s.number);
 395         }
 396       else if (startswith (cur_name, "g:")
 397                || startswith (cur_name, "group:"))
 398         {
 399           /* We have a syscall group.  Let's expand it into a syscall
 400              list before inserting.  */
 401           const char *group_name;
 402
 403           /* Skip over "g:" and "group:" prefix strings.  */
 404           group_name = strchr (cur_name, ':') + 1;
 405
 406           if (!get_syscalls_by_group (gdbarch, group_name, &result))
 407             error (_("Unknown syscall group '%s'."), group_name);
 408         }
 409       else
 410         {
 411           /* We have a name.  Let's check if it's valid and fetch a
 412              list of matching numbers.  */
 413           if (!get_syscalls_by_name (gdbarch, cur_name, &result))
 414             /* Here we have to issue an error instead of a warning,
 415                because GDB cannot do anything useful if there's no
 416                syscall number to be caught.  */
 417             error (_("Unknown syscall name '%s'."), cur_name);
 418         }
 419     }
 420
 421   return result;
 422 }
 423
 424 /* Implement the "catch syscall" command.  */
 425
 426 static void
 427 catch_syscall_command_1 (const char *arg, int from_tty,
 428                          struct cmd_list_element *command)
 429 {
 430   int tempflag;
 431   std::vector<int> filter;
 432   struct syscall s;
 433   struct gdbarch *gdbarch = get_current_arch ();
 434
 435   /* Checking if the feature if supported.  */
 436   if (gdbarch_get_syscall_number_p (gdbarch) == 0)
 437     error (_("The feature 'catch syscall' is not supported on \
 438 this architecture yet."));
 439
 440   tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 441
 442   arg = skip_spaces (arg);
 443
 444   /* We need to do this first "dummy" translation in order
 445      to get the syscall XML file loaded or, most important,
 446      to display a warning to the user if there's no XML file
 447      for his/her architecture.  */
 448   get_syscall_by_number (gdbarch, 0, &s);
 449
 450   /* The allowed syntax is:
 451      catch syscall
 452      catch syscall <name | number> [<name | number> ... <name | number>]
 453
 454      Let's check if there's a syscall name.  */
 455
 456   if (arg != NULL)
 457     filter = catch_syscall_split_args (arg);
 458
 459   create_syscall_event_catchpoint (tempflag, std::move (filter),
 460                                    &catch_syscall_breakpoint_ops);
 461 }
 462
 463
 464 /* Returns 0 if 'bp' is NOT a syscall catchpoint,
 465    non-zero otherwise.  */
 466 static int
 467 is_syscall_catchpoint_enabled (struct breakpoint *bp)
 468 {
 469   if (syscall_catchpoint_p (bp)
 470       && bp->enable_state != bp_disabled
 471       && bp->enable_state != bp_call_disabled)
 472     return 1;
 473   else
 474     return 0;
 475 }
 476
 477 int
 478 catch_syscall_enabled (void)
 479 {
 480   struct catch_syscall_inferior_data *inf_data
 481     = get_catch_syscall_inferior_data (current_inferior ());
 482
 483   return inf_data->total_syscalls_count != 0;
 484 }
 485
 486 /* Helper function for catching_syscall_number.  If B is a syscall
 487    catchpoint for SYSCALL_NUMBER, return 1 (which will make
 488    'breakpoint_find_if' return).  Otherwise, return 0.  */
 489
 490 static int
 491 catching_syscall_number_1 (struct breakpoint *b,
 492                            void *data)
 493 {
 494   int syscall_number = (int) (uintptr_t) data;
 495
 496   if (is_syscall_catchpoint_enabled (b))
 497     {
 498       struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 499
 500       if (!c->syscalls_to_be_caught.empty ())
 501         {
 502           for (int iter : c->syscalls_to_be_caught)
 503             if (syscall_number == iter)
 504               return 1;
 505         }
 506       else
 507         return 1;
 508     }
 509
 510   return 0;
 511 }
 512
 513 int
 514 catching_syscall_number (int syscall_number)
 515 {
 516   struct breakpoint *b = breakpoint_find_if (catching_syscall_number_1,
 517                                          (void *) (uintptr_t) syscall_number);
 518
 519   return b != NULL;
 520 }
 521
 522 /* Complete syscall names.  Used by "catch syscall".  */
 523
 524 static void
 525 catch_syscall_completer (struct cmd_list_element *cmd,
 526                          completion_tracker &tracker,
 527                          const char *text, const char *word)
 528 {
 529   struct gdbarch *gdbarch = get_current_arch ();
 530   gdb::unique_xmalloc_ptr<const char *> group_list;
 531   const char *prefix;
 532
 533   /* Completion considers ':' to be a word separator, so we use this to
 534      verify whether the previous word was a group prefix.  If so, we
 535      build the completion list using group names only.  */
 536   for (prefix = word; prefix != text && prefix[-1] != ' '; prefix--)
 537     ;
 538
 539   if (startswith (prefix, "g:") || startswith (prefix, "group:"))
 540     {
 541       /* Perform completion inside 'group:' namespace only.  */
 542       group_list.reset (get_syscall_group_names (gdbarch));
 543       if (group_list != NULL)
 544         complete_on_enum (tracker, group_list.get (), word, word);
 545     }
 546   else
 547     {
 548       /* Complete with both, syscall names and groups.  */
 549       gdb::unique_xmalloc_ptr<const char *> syscall_list
 550         (get_syscall_names (gdbarch));
 551       group_list.reset (get_syscall_group_names (gdbarch));
 552
 553       const char **group_ptr = group_list.get ();
 554
 555       /* Hold on to strings while we're using them.  */
 556       std::vector<std::string> holders;
 557
 558       /* Append "group:" prefix to syscall groups.  */
 559       for (int i = 0; group_ptr[i] != NULL; i++)
 560         holders.push_back (string_printf ("group:%s", group_ptr[i]));
 561
 562       for (int i = 0; group_ptr[i] != NULL; i++)
 563         group_ptr[i] = holders[i].c_str ();
 564
 565       if (syscall_list != NULL)
 566         complete_on_enum (tracker, syscall_list.get (), word, word);
 567       if (group_list != NULL)
 568         complete_on_enum (tracker, group_ptr, word, word);
 569     }
 570 }
 571
 572 static void
 573 clear_syscall_counts (struct inferior *inf)
 574 {
 575   struct catch_syscall_inferior_data *inf_data
 576     = get_catch_syscall_inferior_data (inf);
 577
 578   inf_data->total_syscalls_count = 0;
 579   inf_data->any_syscall_count = 0;
 580   inf_data->syscalls_counts.clear ();
 581 }
 582
 583 static void
 584 initialize_syscall_catchpoint_ops (void)
 585 {
 586   struct breakpoint_ops *ops;
 587
 588   initialize_breakpoint_ops ();
 589
 590   /* Syscall catchpoints.  */
 591   ops = &catch_syscall_breakpoint_ops;
 592   *ops = base_breakpoint_ops;
 593   ops->insert_location = insert_catch_syscall;
 594   ops->remove_location = remove_catch_syscall;
 595   ops->breakpoint_hit = breakpoint_hit_catch_syscall;
 596   ops->print_it = print_it_catch_syscall;
 597   ops->print_one = print_one_catch_syscall;
 598   ops->print_mention = print_mention_catch_syscall;
 599   ops->print_recreate = print_recreate_catch_syscall;
 600 }
 601
 602 void
 603 _initialize_break_catch_syscall (void)
 604 {
 605   initialize_syscall_catchpoint_ops ();
 606
 607   gdb::observers::inferior_exit.attach (clear_syscall_counts);
 608
 609   add_catch_command ("syscall", _("\
 610 Catch system calls by their names, groups and/or numbers.\n\
 611 Arguments say which system calls to catch.  If no arguments are given,\n\
 612 every system call will be caught.  Arguments, if given, should be one\n\
 613 or more system call names (if your system supports that), system call\n\
 614 groups or system call numbers."),
 615                      catch_syscall_command_1,
 616                      catch_syscall_completer,
 617                      CATCH_PERMANENT,
 618                      CATCH_TEMPORARY);
 619 }