gdb/break-catch-syscall.c

   1 /* Everything about syscall catchpoints, for GDB.
   2
   3    Copyright (C) 2009-2022 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 #include "cli/cli-decode.h"
  34
  35 /* An instance of this type is used to represent a syscall
  36    catchpoint.  */
  37
  38 struct syscall_catchpoint : public catchpoint
  39 {
  40   syscall_catchpoint (struct gdbarch *gdbarch, bool tempflag,
  41                       std::vector<int> &&calls)
  42     : catchpoint (gdbarch, tempflag, nullptr),
  43       syscalls_to_be_caught (std::move (calls))
  44   {
  45   }
  46
  47   int insert_location (struct bp_location *) override;
  48   int remove_location (struct bp_location *,
  49                        enum remove_bp_reason reason) override;
  50   int breakpoint_hit (const struct bp_location *bl,
  51                       const address_space *aspace,
  52                       CORE_ADDR bp_addr,
  53                       const target_waitstatus &ws) override;
  54   enum print_stop_action print_it (const bpstat *bs) const override;
  55   bool print_one (bp_location **) const override;
  56   void print_mention () const override;
  57   void print_recreate (struct ui_file *fp) const override;
  58
  59   /* Syscall numbers used for the 'catch syscall' feature.  If no
  60      syscall has been specified for filtering, it is empty.
  61      Otherwise, it holds a list of all syscalls to be caught.  */
  62   std::vector<int> syscalls_to_be_caught;
  63 };
  64
  65 struct catch_syscall_inferior_data
  66 {
  67   /* We keep a count of the number of times the user has requested a
  68      particular syscall to be tracked, and pass this information to the
  69      target.  This lets capable targets implement filtering directly.  */
  70
  71   /* Number of times that "any" syscall is requested.  */
  72   int any_syscall_count;
  73
  74   /* Count of each system call.  */
  75   std::vector<int> syscalls_counts;
  76
  77   /* This counts all syscall catch requests, so we can readily determine
  78      if any catching is necessary.  */
  79   int total_syscalls_count;
  80 };
  81
  82 static const struct inferior_key<struct catch_syscall_inferior_data>
  83   catch_syscall_inferior_data;
  84
  85 static struct catch_syscall_inferior_data *
  86 get_catch_syscall_inferior_data (struct inferior *inf)
  87 {
  88   struct catch_syscall_inferior_data *inf_data;
  89
  90   inf_data = catch_syscall_inferior_data.get (inf);
  91   if (inf_data == NULL)
  92     inf_data = catch_syscall_inferior_data.emplace (inf);
  93
  94   return inf_data;
  95 }
  96
  97 /* Implement the "insert" method for syscall catchpoints.  */
  98
  99 int
 100 syscall_catchpoint::insert_location (struct bp_location *bl)
 101 {
 102   struct inferior *inf = current_inferior ();
 103   struct catch_syscall_inferior_data *inf_data
 104     = get_catch_syscall_inferior_data (inf);
 105
 106   ++inf_data->total_syscalls_count;
 107   if (syscalls_to_be_caught.empty ())
 108     ++inf_data->any_syscall_count;
 109   else
 110     {
 111       for (int iter : syscalls_to_be_caught)
 112         {
 113           if (iter >= inf_data->syscalls_counts.size ())
 114             inf_data->syscalls_counts.resize (iter + 1);
 115           ++inf_data->syscalls_counts[iter];
 116         }
 117     }
 118
 119   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 120                                         inf_data->total_syscalls_count != 0,
 121                                         inf_data->any_syscall_count,
 122                                         inf_data->syscalls_counts);
 123 }
 124
 125 /* Implement the "remove" method for syscall catchpoints.  */
 126
 127 int
 128 syscall_catchpoint::remove_location (struct bp_location *bl,
 129                                      enum remove_bp_reason reason)
 130 {
 131   struct inferior *inf = current_inferior ();
 132   struct catch_syscall_inferior_data *inf_data
 133     = get_catch_syscall_inferior_data (inf);
 134
 135   --inf_data->total_syscalls_count;
 136   if (syscalls_to_be_caught.empty ())
 137     --inf_data->any_syscall_count;
 138   else
 139     {
 140       for (int iter : syscalls_to_be_caught)
 141         {
 142           if (iter >= inf_data->syscalls_counts.size ())
 143             /* Shouldn't happen.  */
 144             continue;
 145           --inf_data->syscalls_counts[iter];
 146         }
 147     }
 148
 149   return target_set_syscall_catchpoint (inferior_ptid.pid (),
 150                                         inf_data->total_syscalls_count != 0,
 151                                         inf_data->any_syscall_count,
 152                                         inf_data->syscalls_counts);
 153 }
 154
 155 /* Implement the "breakpoint_hit" method for syscall catchpoints.  */
 156
 157 int
 158 syscall_catchpoint::breakpoint_hit (const struct bp_location *bl,
 159                                     const address_space *aspace,
 160                                     CORE_ADDR bp_addr,
 161                                     const target_waitstatus &ws)
 162 {
 163   /* We must check if we are catching specific syscalls in this
 164      breakpoint.  If we are, then we must guarantee that the called
 165      syscall is the same syscall we are catching.  */
 166   int syscall_number = 0;
 167
 168   if (ws.kind () != TARGET_WAITKIND_SYSCALL_ENTRY
 169       && ws.kind () != TARGET_WAITKIND_SYSCALL_RETURN)
 170     return 0;
 171
 172   syscall_number = ws.syscall_number ();
 173
 174   /* Now, checking if the syscall is the same.  */
 175   if (!syscalls_to_be_caught.empty ())
 176     {
 177       for (int iter : syscalls_to_be_caught)
 178         if (syscall_number == iter)
 179           return 1;
 180
 181       return 0;
 182     }
 183
 184   return 1;
 185 }
 186
 187 /* Implement the "print_it" method for syscall catchpoints.  */
 188
 189 enum print_stop_action
 190 syscall_catchpoint::print_it (const bpstat *bs) const
 191 {
 192   struct ui_out *uiout = current_uiout;
 193   struct breakpoint *b = bs->breakpoint_at;
 194   /* These are needed because we want to know in which state a
 195      syscall is.  It can be in the TARGET_WAITKIND_SYSCALL_ENTRY
 196      or TARGET_WAITKIND_SYSCALL_RETURN, and depending on it we
 197      must print "called syscall" or "returned from syscall".  */
 198   struct target_waitstatus last;
 199   struct syscall s;
 200   struct gdbarch *gdbarch = b->gdbarch;
 201
 202   get_last_target_status (nullptr, nullptr, &last);
 203
 204   get_syscall_by_number (gdbarch, last.syscall_number (), &s);
 205
 206   annotate_catchpoint (b->number);
 207   maybe_print_thread_hit_breakpoint (uiout);
 208
 209   if (b->disposition == disp_del)
 210     uiout->text ("Temporary catchpoint ");
 211   else
 212     uiout->text ("Catchpoint ");
 213   if (uiout->is_mi_like_p ())
 214     {
 215       uiout->field_string ("reason",
 216                            async_reason_lookup (last.kind () == TARGET_WAITKIND_SYSCALL_ENTRY
 217                                                 ? EXEC_ASYNC_SYSCALL_ENTRY
 218                                                 : EXEC_ASYNC_SYSCALL_RETURN));
 219       uiout->field_string ("disp", bpdisp_text (b->disposition));
 220     }
 221   uiout->field_signed ("bkptno", b->number);
 222
 223   if (last.kind () == TARGET_WAITKIND_SYSCALL_ENTRY)
 224     uiout->text (" (call to syscall ");
 225   else
 226     uiout->text (" (returned from syscall ");
 227
 228   if (s.name == NULL || uiout->is_mi_like_p ())
 229     uiout->field_signed ("syscall-number", last.syscall_number ());
 230   if (s.name != NULL)
 231     uiout->field_string ("syscall-name", s.name);
 232
 233   uiout->text ("), ");
 234
 235   return PRINT_SRC_AND_LOC;
 236 }
 237
 238 /* Implement the "print_one" method for syscall catchpoints.  */
 239
 240 bool
 241 syscall_catchpoint::print_one (bp_location **last_loc) const
 242 {
 243   struct value_print_options opts;
 244   struct ui_out *uiout = current_uiout;
 245   struct gdbarch *gdbarch = loc->owner->gdbarch;
 246
 247   get_user_print_options (&opts);
 248   /* Field 4, the address, is omitted (which makes the columns not
 249      line up too nicely with the headers, but the effect is relatively
 250      readable).  */
 251   if (opts.addressprint)
 252     uiout->field_skip ("addr");
 253   annotate_field (5);
 254
 255   if (syscalls_to_be_caught.size () > 1)
 256     uiout->text ("syscalls \"");
 257   else
 258     uiout->text ("syscall \"");
 259
 260   if (!syscalls_to_be_caught.empty ())
 261     {
 262       std::string text;
 263
 264       bool first = true;
 265       for (int iter : syscalls_to_be_caught)
 266         {
 267           struct syscall s;
 268           get_syscall_by_number (gdbarch, iter, &s);
 269
 270           if (!first)
 271             text += ", ";
 272           first = false;
 273
 274           if (s.name != NULL)
 275             text += s.name;
 276           else
 277             text += std::to_string (iter);
 278         }
 279       uiout->field_string ("what", text.c_str ());
 280     }
 281   else
 282     uiout->field_string ("what", "<any syscall>", metadata_style.style ());
 283   uiout->text ("\" ");
 284
 285   if (uiout->is_mi_like_p ())
 286     uiout->field_string ("catch-type", "syscall");
 287
 288   return true;
 289 }
 290
 291 /* Implement the "print_mention" method for syscall catchpoints.  */
 292
 293 void
 294 syscall_catchpoint::print_mention () const
 295 {
 296   struct gdbarch *gdbarch = loc->owner->gdbarch;
 297
 298   if (!syscalls_to_be_caught.empty ())
 299     {
 300       if (syscalls_to_be_caught.size () > 1)
 301         gdb_printf (_("Catchpoint %d (syscalls"), number);
 302       else
 303         gdb_printf (_("Catchpoint %d (syscall"), number);
 304
 305       for (int iter : syscalls_to_be_caught)
 306         {
 307           struct syscall s;
 308           get_syscall_by_number (gdbarch, iter, &s);
 309
 310           if (s.name != NULL)
 311             gdb_printf (" '%s' [%d]", s.name, s.number);
 312           else
 313             gdb_printf (" %d", s.number);
 314         }
 315       gdb_printf (")");
 316     }
 317   else
 318     gdb_printf (_("Catchpoint %d (any syscall)"), number);
 319 }
 320
 321 /* Implement the "print_recreate" method for syscall catchpoints.  */
 322
 323 void
 324 syscall_catchpoint::print_recreate (struct ui_file *fp) const
 325 {
 326   struct gdbarch *gdbarch = loc->gdbarch;
 327
 328   gdb_printf (fp, "catch syscall");
 329
 330   for (int iter : syscalls_to_be_caught)
 331     {
 332       struct syscall s;
 333
 334       get_syscall_by_number (gdbarch, iter, &s);
 335       if (s.name != NULL)
 336         gdb_printf (fp, " %s", s.name);
 337       else
 338         gdb_printf (fp, " %d", s.number);
 339     }
 340
 341   print_recreate_thread (fp);
 342 }
 343
 344 /* Returns non-zero if 'b' is a syscall catchpoint.  */
 345
 346 static int
 347 syscall_catchpoint_p (struct breakpoint *b)
 348 {
 349   return dynamic_cast<syscall_catchpoint *> (b) != nullptr;
 350 }
 351
 352 static void
 353 create_syscall_event_catchpoint (int tempflag, std::vector<int> &&filter)
 354 {
 355   struct gdbarch *gdbarch = get_current_arch ();
 356
 357   std::unique_ptr<syscall_catchpoint> c
 358     (new syscall_catchpoint (gdbarch, tempflag, std::move (filter)));
 359
 360   install_breakpoint (0, std::move (c), 1);
 361 }
 362
 363 /* Splits the argument using space as delimiter.  */
 364
 365 static std::vector<int>
 366 catch_syscall_split_args (const char *arg)
 367 {
 368   std::vector<int> result;
 369   struct gdbarch *gdbarch = target_gdbarch ();
 370
 371   while (*arg != '\0')
 372     {
 373       int i, syscall_number;
 374       char *endptr;
 375       char cur_name[128];
 376       struct syscall s;
 377
 378       /* Skip whitespace.  */
 379       arg = skip_spaces (arg);
 380
 381       for (i = 0; i < 127 && arg[i] && !isspace (arg[i]); ++i)
 382         cur_name[i] = arg[i];
 383       cur_name[i] = '\0';
 384       arg += i;
 385
 386       /* Check if the user provided a syscall name, group, or a number.  */
 387       syscall_number = (int) strtol (cur_name, &endptr, 0);
 388       if (*endptr == '\0')
 389         {
 390           if (syscall_number < 0)
 391             error (_("Unknown syscall number '%d'."), syscall_number);
 392           get_syscall_by_number (gdbarch, syscall_number, &s);
 393           result.push_back (s.number);
 394         }
 395       else if (startswith (cur_name, "g:")
 396                || startswith (cur_name, "group:"))
 397         {
 398           /* We have a syscall group.  Let's expand it into a syscall
 399              list before inserting.  */
 400           const char *group_name;
 401
 402           /* Skip over "g:" and "group:" prefix strings.  */
 403           group_name = strchr (cur_name, ':') + 1;
 404
 405           if (!get_syscalls_by_group (gdbarch, group_name, &result))
 406             error (_("Unknown syscall group '%s'."), group_name);
 407         }
 408       else
 409         {
 410           /* We have a name.  Let's check if it's valid and fetch a
 411              list of matching numbers.  */
 412           if (!get_syscalls_by_name (gdbarch, cur_name, &result))
 413             /* Here we have to issue an error instead of a warning,
 414                because GDB cannot do anything useful if there's no
 415                syscall number to be caught.  */
 416             error (_("Unknown syscall name '%s'."), cur_name);
 417         }
 418     }
 419
 420   return result;
 421 }
 422
 423 /* Implement the "catch syscall" command.  */
 424
 425 static void
 426 catch_syscall_command_1 (const char *arg, int from_tty,
 427                          struct cmd_list_element *command)
 428 {
 429   int tempflag;
 430   std::vector<int> filter;
 431   struct syscall s;
 432   struct gdbarch *gdbarch = get_current_arch ();
 433
 434   /* Checking if the feature if supported.  */
 435   if (gdbarch_get_syscall_number_p (gdbarch) == 0)
 436     error (_("The feature 'catch syscall' is not supported on \
 437 this architecture yet."));
 438
 439   tempflag = command->context () == CATCH_TEMPORARY;
 440
 441   arg = skip_spaces (arg);
 442
 443   /* We need to do this first "dummy" translation in order
 444      to get the syscall XML file loaded or, most important,
 445      to display a warning to the user if there's no XML file
 446      for his/her architecture.  */
 447   get_syscall_by_number (gdbarch, 0, &s);
 448
 449   /* The allowed syntax is:
 450      catch syscall
 451      catch syscall <name | number> [<name | number> ... <name | number>]
 452
 453      Let's check if there's a syscall name.  */
 454
 455   if (arg != NULL)
 456     filter = catch_syscall_split_args (arg);
 457
 458   create_syscall_event_catchpoint (tempflag, std::move (filter));
 459 }
 460
 461
 462 /* Returns 0 if 'bp' is NOT a syscall catchpoint,
 463    non-zero otherwise.  */
 464 static int
 465 is_syscall_catchpoint_enabled (struct breakpoint *bp)
 466 {
 467   if (syscall_catchpoint_p (bp)
 468       && bp->enable_state != bp_disabled
 469       && bp->enable_state != bp_call_disabled)
 470     return 1;
 471   else
 472     return 0;
 473 }
 474
 475 int
 476 catch_syscall_enabled (void)
 477 {
 478   struct catch_syscall_inferior_data *inf_data
 479     = get_catch_syscall_inferior_data (current_inferior ());
 480
 481   return inf_data->total_syscalls_count != 0;
 482 }
 483
 484 /* Helper function for catching_syscall_number.  return true if B is a syscall
 485    catchpoint for SYSCALL_NUMBER, else false.  */
 486
 487 static bool
 488 catching_syscall_number_1 (struct breakpoint *b, int syscall_number)
 489 {
 490
 491   if (is_syscall_catchpoint_enabled (b))
 492     {
 493       struct syscall_catchpoint *c = (struct syscall_catchpoint *) b;
 494
 495       if (!c->syscalls_to_be_caught.empty ())
 496         {
 497           for (int iter : c->syscalls_to_be_caught)
 498             if (syscall_number == iter)
 499               return true;
 500         }
 501       else
 502         return true;
 503     }
 504
 505   return false;
 506 }
 507
 508 bool
 509 catching_syscall_number (int syscall_number)
 510 {
 511   for (breakpoint *b : all_breakpoints ())
 512     if (catching_syscall_number_1 (b, syscall_number))
 513       return true;
 514
 515   return false;
 516 }
 517
 518 /* Complete syscall names.  Used by "catch syscall".  */
 519
 520 static void
 521 catch_syscall_completer (struct cmd_list_element *cmd,
 522                          completion_tracker &tracker,
 523                          const char *text, const char *word)
 524 {
 525   struct gdbarch *gdbarch = get_current_arch ();
 526   gdb::unique_xmalloc_ptr<const char *> group_list;
 527   const char *prefix;
 528
 529   /* Completion considers ':' to be a word separator, so we use this to
 530      verify whether the previous word was a group prefix.  If so, we
 531      build the completion list using group names only.  */
 532   for (prefix = word; prefix != text && prefix[-1] != ' '; prefix--)
 533     ;
 534
 535   if (startswith (prefix, "g:") || startswith (prefix, "group:"))
 536     {
 537       /* Perform completion inside 'group:' namespace only.  */
 538       group_list.reset (get_syscall_group_names (gdbarch));
 539       if (group_list != NULL)
 540         complete_on_enum (tracker, group_list.get (), word, word);
 541     }
 542   else
 543     {
 544       /* Complete with both, syscall names and groups.  */
 545       gdb::unique_xmalloc_ptr<const char *> syscall_list
 546         (get_syscall_names (gdbarch));
 547       group_list.reset (get_syscall_group_names (gdbarch));
 548
 549       const char **group_ptr = group_list.get ();
 550
 551       /* Hold on to strings while we're using them.  */
 552       std::vector<std::string> holders;
 553
 554       /* Append "group:" prefix to syscall groups.  */
 555       for (int i = 0; group_ptr[i] != NULL; i++)
 556         holders.push_back (string_printf ("group:%s", group_ptr[i]));
 557
 558       for (int i = 0; group_ptr[i] != NULL; i++)
 559         group_ptr[i] = holders[i].c_str ();
 560
 561       if (syscall_list != NULL)
 562         complete_on_enum (tracker, syscall_list.get (), word, word);
 563       if (group_list != NULL)
 564         complete_on_enum (tracker, group_ptr, word, word);
 565     }
 566 }
 567
 568 static void
 569 clear_syscall_counts (struct inferior *inf)
 570 {
 571   struct catch_syscall_inferior_data *inf_data
 572     = get_catch_syscall_inferior_data (inf);
 573
 574   inf_data->total_syscalls_count = 0;
 575   inf_data->any_syscall_count = 0;
 576   inf_data->syscalls_counts.clear ();
 577 }
 578
 579 void _initialize_break_catch_syscall ();
 580 void
 581 _initialize_break_catch_syscall ()
 582 {
 583   gdb::observers::inferior_exit.attach (clear_syscall_counts,
 584                                         "break-catch-syscall");
 585
 586   add_catch_command ("syscall", _("\
 587 Catch system calls by their names, groups and/or numbers.\n\
 588 Arguments say which system calls to catch.  If no arguments are given,\n\
 589 every system call will be caught.  Arguments, if given, should be one\n\
 590 or more system call names (if your system supports that), system call\n\
 591 groups or system call numbers."),
 592                      catch_syscall_command_1,
 593                      catch_syscall_completer,
 594                      CATCH_PERMANENT,
 595                      CATCH_TEMPORARY);
 596 }