gdbserver/linux-low.h

   1 /* Internal interfaces for the GNU/Linux specific target code for gdbserver.
   2    Copyright (C) 2002-2020 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef GDBSERVER_LINUX_LOW_H
  20 #define GDBSERVER_LINUX_LOW_H
  21
  22 #include "nat/linux-nat.h"
  23 #include "nat/gdb_thread_db.h"
  24 #include <signal.h>
  25
  26 #include "gdbthread.h"
  27 #include "gdb_proc_service.h"
  28
  29 /* Included for ptrace type definitions.  */
  30 #include "nat/linux-ptrace.h"
  31 #include "target/waitstatus.h" /* For enum target_stop_reason.  */
  32 #include "tracepoint.h"
  33
  34 #define PTRACE_XFER_TYPE long
  35
  36 #ifdef HAVE_LINUX_REGSETS
  37 typedef void (*regset_fill_func) (struct regcache *, void *);
  38 typedef void (*regset_store_func) (struct regcache *, const void *);
  39 enum regset_type {
  40   GENERAL_REGS,
  41   FP_REGS,
  42   EXTENDED_REGS,
  43   OPTIONAL_REGS, /* Do not error if the regset cannot be accessed.  */
  44 };
  45
  46 /* The arch's regsets array initializer must be terminated with a NULL
  47    regset.  */
  48 #define NULL_REGSET \
  49   { 0, 0, 0, -1, (enum regset_type) -1, NULL, NULL }
  50
  51 struct regset_info
  52 {
  53   int get_request, set_request;
  54   /* If NT_TYPE isn't 0, it will be passed to ptrace as the 3rd
  55      argument and the 4th argument should be "const struct iovec *".  */
  56   int nt_type;
  57   int size;
  58   enum regset_type type;
  59   regset_fill_func fill_function;
  60   regset_store_func store_function;
  61 };
  62
  63 /* Aggregation of all the supported regsets of a given
  64    architecture/mode.  */
  65
  66 struct regsets_info
  67 {
  68   /* The regsets array.  */
  69   struct regset_info *regsets;
  70
  71   /* The number of regsets in the REGSETS array.  */
  72   int num_regsets;
  73
  74   /* If we get EIO on a regset, do not try it again.  Note the set of
  75      supported regsets may depend on processor mode on biarch
  76      machines.  This is a (lazily allocated) array holding one boolean
  77      byte (0/1) per regset, with each element corresponding to the
  78      regset in the REGSETS array above at the same offset.  */
  79   char *disabled_regsets;
  80 };
  81
  82 #endif
  83
  84 /* Mapping between the general-purpose registers in `struct user'
  85    format and GDB's register array layout.  */
  86
  87 struct usrregs_info
  88 {
  89   /* The number of registers accessible.  */
  90   int num_regs;
  91
  92   /* The registers map.  */
  93   int *regmap;
  94 };
  95
  96 /* All info needed to access an architecture/mode's registers.  */
  97
  98 struct regs_info
  99 {
 100   /* Regset support bitmap: 1 for registers that are transferred as a part
 101      of a regset, 0 for ones that need to be handled individually.  This
 102      can be NULL if all registers are transferred with regsets or regsets
 103      are not supported.  */
 104   unsigned char *regset_bitmap;
 105
 106   /* Info used when accessing registers with PTRACE_PEEKUSER /
 107      PTRACE_POKEUSER.  This can be NULL if all registers are
 108      transferred with regsets  .*/
 109   struct usrregs_info *usrregs;
 110
 111 #ifdef HAVE_LINUX_REGSETS
 112   /* Info used when accessing registers with regsets.  */
 113   struct regsets_info *regsets_info;
 114 #endif
 115 };
 116
 117 struct process_info_private
 118 {
 119   /* Arch-specific additions.  */
 120   struct arch_process_info *arch_private;
 121
 122   /* libthread_db-specific additions.  Not NULL if this process has loaded
 123      thread_db, and it is active.  */
 124   struct thread_db *thread_db;
 125
 126   /* &_r_debug.  0 if not yet determined.  -1 if no PT_DYNAMIC in Phdrs.  */
 127   CORE_ADDR r_debug;
 128 };
 129
 130 struct lwp_info;
 131
 132 struct linux_target_ops
 133 {
 134   int (*breakpoint_at) (CORE_ADDR pc);
 135
 136   /* Breakpoint and watchpoint related functions.  See target.h for
 137      comments.  */
 138   int (*supports_z_point_type) (char z_type);
 139   int (*insert_point) (enum raw_bkpt_type type, CORE_ADDR addr,
 140                        int size, struct raw_breakpoint *bp);
 141   int (*remove_point) (enum raw_bkpt_type type, CORE_ADDR addr,
 142                        int size, struct raw_breakpoint *bp);
 143
 144   int (*stopped_by_watchpoint) (void);
 145   CORE_ADDR (*stopped_data_address) (void);
 146
 147   /* Hooks to reformat register data for PEEKUSR/POKEUSR (in particular
 148      for registers smaller than an xfer unit).  */
 149   void (*collect_ptrace_register) (struct regcache *regcache,
 150                                    int regno, char *buf);
 151   void (*supply_ptrace_register) (struct regcache *regcache,
 152                                   int regno, const char *buf);
 153
 154   /* Hook to convert from target format to ptrace format and back.
 155      Returns true if any conversion was done; false otherwise.
 156      If DIRECTION is 1, then copy from INF to NATIVE.
 157      If DIRECTION is 0, copy from NATIVE to INF.  */
 158   int (*siginfo_fixup) (siginfo_t *native, gdb_byte *inf, int direction);
 159
 160   /* Hook to call when a new process is created or attached to.
 161      If extra per-process architecture-specific data is needed,
 162      allocate it here.  */
 163   struct arch_process_info * (*new_process) (void);
 164
 165   /* Hook to call when a process is being deleted.  If extra per-process
 166      architecture-specific data is needed, delete it here.  */
 167   void (*delete_process) (struct arch_process_info *info);
 168
 169   /* Hook to call when a new thread is detected.
 170      If extra per-thread architecture-specific data is needed,
 171      allocate it here.  */
 172   void (*new_thread) (struct lwp_info *);
 173
 174   /* Hook to call when a thread is being deleted.  If extra per-thread
 175      architecture-specific data is needed, delete it here.  */
 176   void (*delete_thread) (struct arch_lwp_info *);
 177
 178   /* Hook to call, if any, when a new fork is attached.  */
 179   void (*new_fork) (struct process_info *parent, struct process_info *child);
 180
 181   /* Hook to call prior to resuming a thread.  */
 182   void (*prepare_to_resume) (struct lwp_info *);
 183
 184   /* Hook to support target specific qSupported.  */
 185   void (*process_qsupported) (char **, int count);
 186
 187   /* Returns true if the low target supports tracepoints.  */
 188   int (*supports_tracepoints) (void);
 189
 190   /* Fill ADDRP with the thread area address of LWPID.  Returns 0 on
 191      success, -1 on failure.  */
 192   int (*get_thread_area) (int lwpid, CORE_ADDR *addrp);
 193
 194   /* Install a fast tracepoint jump pad.  See target.h for
 195      comments.  */
 196   int (*install_fast_tracepoint_jump_pad) (CORE_ADDR tpoint, CORE_ADDR tpaddr,
 197                                            CORE_ADDR collector,
 198                                            CORE_ADDR lockaddr,
 199                                            ULONGEST orig_size,
 200                                            CORE_ADDR *jump_entry,
 201                                            CORE_ADDR *trampoline,
 202                                            ULONGEST *trampoline_size,
 203                                            unsigned char *jjump_pad_insn,
 204                                            ULONGEST *jjump_pad_insn_size,
 205                                            CORE_ADDR *adjusted_insn_addr,
 206                                            CORE_ADDR *adjusted_insn_addr_end,
 207                                            char *err);
 208
 209   /* Return the bytecode operations vector for the current inferior.
 210      Returns NULL if bytecode compilation is not supported.  */
 211   struct emit_ops *(*emit_ops) (void);
 212
 213   /* Return the minimum length of an instruction that can be safely overwritten
 214      for use as a fast tracepoint.  */
 215   int (*get_min_fast_tracepoint_insn_len) (void);
 216
 217   /* Returns true if the low target supports range stepping.  */
 218   int (*supports_range_stepping) (void);
 219
 220   /* See target.h.  */
 221   int (*supports_hardware_single_step) (void);
 222
 223   /* Fill *SYSNO with the syscall nr trapped.  Only to be called when
 224      inferior is stopped due to SYSCALL_SIGTRAP.  */
 225   void (*get_syscall_trapinfo) (struct regcache *regcache, int *sysno);
 226
 227   /* See target.h.  */
 228   int (*get_ipa_tdesc_idx) (void);
 229 };
 230
 231 extern struct linux_target_ops the_low_target;
 232
 233 /* Target ops definitions for a Linux target.  */
 234
 235 class linux_process_target : public process_stratum_target
 236 {
 237 public:
 238
 239   int create_inferior (const char *program,
 240                        const std::vector<char *> &program_args) override;
 241
 242   void post_create_inferior () override;
 243
 244   int attach (unsigned long pid) override;
 245
 246   int kill (process_info *proc) override;
 247
 248   int detach (process_info *proc) override;
 249
 250   void mourn (process_info *proc) override;
 251
 252   void join (int pid) override;
 253
 254   bool thread_alive (ptid_t pid) override;
 255
 256   void resume (thread_resume *resume_info, size_t n) override;
 257
 258   ptid_t wait (ptid_t ptid, target_waitstatus *status,
 259                int options) override;
 260
 261   void fetch_registers (regcache *regcache, int regno) override;
 262
 263   void store_registers (regcache *regcache, int regno) override;
 264
 265   int prepare_to_access_memory () override;
 266
 267   void done_accessing_memory () override;
 268
 269   int read_memory (CORE_ADDR memaddr, unsigned char *myaddr,
 270                    int len) override;
 271
 272   int write_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 273                     int len) override;
 274
 275   void look_up_symbols () override;
 276
 277   void request_interrupt () override;
 278
 279   bool supports_read_auxv () override;
 280
 281   int read_auxv (CORE_ADDR offset, unsigned char *myaddr,
 282                  unsigned int len) override;
 283
 284   bool supports_z_point_type (char z_type) override;
 285
 286   int insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
 287                     int size, raw_breakpoint *bp) override;
 288
 289   int remove_point (enum raw_bkpt_type type, CORE_ADDR addr,
 290                     int size, raw_breakpoint *bp) override;
 291
 292   bool stopped_by_sw_breakpoint () override;
 293
 294   bool supports_stopped_by_sw_breakpoint () override;
 295
 296   bool stopped_by_hw_breakpoint () override;
 297
 298   bool supports_stopped_by_hw_breakpoint () override;
 299
 300   bool supports_hardware_single_step () override;
 301
 302   bool stopped_by_watchpoint () override;
 303
 304   CORE_ADDR stopped_data_address () override;
 305
 306   bool supports_read_offsets () override;
 307
 308   int read_offsets (CORE_ADDR *text, CORE_ADDR *data) override;
 309
 310   bool supports_get_tls_address () override;
 311
 312   int get_tls_address (thread_info *thread, CORE_ADDR offset,
 313                        CORE_ADDR load_module, CORE_ADDR *address) override;
 314
 315   bool supports_qxfer_osdata () override;
 316
 317   int qxfer_osdata (const char *annex, unsigned char *readbuf,
 318                     unsigned const char *writebuf,
 319                     CORE_ADDR offset, int len) override;
 320
 321   bool supports_qxfer_siginfo () override;
 322
 323   int qxfer_siginfo (const char *annex, unsigned char *readbuf,
 324                      unsigned const char *writebuf,
 325                      CORE_ADDR offset, int len) override;
 326
 327   bool supports_non_stop () override;
 328
 329   bool async (bool enable) override;
 330
 331   int start_non_stop (bool enable) override;
 332
 333   bool supports_multi_process () override;
 334
 335   bool supports_fork_events () override;
 336
 337   bool supports_vfork_events () override;
 338
 339   bool supports_exec_events () override;
 340
 341   void handle_new_gdb_connection () override;
 342
 343   int handle_monitor_command (char *mon) override;
 344
 345   int core_of_thread (ptid_t ptid) override;
 346
 347 #if defined PT_GETDSBT || defined PTRACE_GETFDPIC
 348   bool supports_read_loadmap () override;
 349
 350   int read_loadmap (const char *annex, CORE_ADDR offset,
 351                     unsigned char *myaddr, unsigned int len) override;
 352 #endif
 353
 354   void process_qsupported (char **features, int count) override;
 355
 356   bool supports_tracepoints () override;
 357
 358   CORE_ADDR read_pc (regcache *regcache) override;
 359
 360   void write_pc (regcache *regcache, CORE_ADDR pc) override;
 361
 362   bool supports_thread_stopped () override;
 363
 364   bool thread_stopped (thread_info *thread) override;
 365
 366   void pause_all (bool freeze) override;
 367
 368   void unpause_all (bool unfreeze) override;
 369
 370   void stabilize_threads () override;
 371
 372   bool supports_fast_tracepoints () override;
 373
 374   int install_fast_tracepoint_jump_pad (CORE_ADDR tpoint,
 375                                         CORE_ADDR tpaddr,
 376                                         CORE_ADDR collector,
 377                                         CORE_ADDR lockaddr,
 378                                         ULONGEST orig_size,
 379                                         CORE_ADDR *jump_entry,
 380                                         CORE_ADDR *trampoline,
 381                                         ULONGEST *trampoline_size,
 382                                         unsigned char *jjump_pad_insn,
 383                                         ULONGEST *jjump_pad_insn_size,
 384                                         CORE_ADDR *adjusted_insn_addr,
 385                                         CORE_ADDR *adjusted_insn_addr_end,
 386                                         char *err) override;
 387
 388   int get_min_fast_tracepoint_insn_len () override;
 389
 390   struct emit_ops *emit_ops () override;
 391
 392   bool supports_disable_randomization () override;
 393
 394   bool supports_qxfer_libraries_svr4 () override;
 395
 396   int qxfer_libraries_svr4 (const char *annex,
 397                             unsigned char *readbuf,
 398                             unsigned const char *writebuf,
 399                             CORE_ADDR offset, int len) override;
 400
 401   bool supports_agent () override;
 402
 403 #ifdef HAVE_LINUX_BTRACE
 404   btrace_target_info *enable_btrace (ptid_t ptid,
 405                                      const btrace_config *conf) override;
 406
 407   int disable_btrace (btrace_target_info *tinfo) override;
 408
 409   int read_btrace (btrace_target_info *tinfo, buffer *buf,
 410                    enum btrace_read_type type) override;
 411
 412   int read_btrace_conf (const btrace_target_info *tinfo,
 413                         buffer *buf) override;
 414 #endif
 415
 416   bool supports_range_stepping () override;
 417
 418   bool supports_pid_to_exec_file () override;
 419
 420   char *pid_to_exec_file (int pid) override;
 421
 422   bool supports_multifs () override;
 423
 424   int multifs_open (int pid, const char *filename, int flags,
 425                     mode_t mode) override;
 426
 427   int multifs_unlink (int pid, const char *filename) override;
 428
 429   ssize_t multifs_readlink (int pid, const char *filename, char *buf,
 430                             size_t bufsiz) override;
 431
 432   const char *thread_name (ptid_t thread) override;
 433
 434 #if USE_THREAD_DB
 435   bool thread_handle (ptid_t ptid, gdb_byte **handle,
 436                       int *handle_len) override;
 437 #endif
 438
 439   bool supports_catch_syscall () override;
 440
 441   int get_ipa_tdesc_idx () override;
 442
 443   /* Return the information to access registers.  This has public
 444      visibility because proc-service uses it.  */
 445   virtual const regs_info *get_regs_info () = 0;
 446
 447 private:
 448
 449   /* Handle a GNU/Linux extended wait response.  If we see a clone,
 450      fork, or vfork event, we need to add the new LWP to our list
 451      (and return 0 so as not to report the trap to higher layers).
 452      If we see an exec event, we will modify ORIG_EVENT_LWP to point
 453      to a new LWP representing the new program.  */
 454   int handle_extended_wait (lwp_info **orig_event_lwp, int wstat);
 455
 456   /* Do low-level handling of the event, and check if we should go on
 457      and pass it to caller code.  Return the affected lwp if we are, or
 458      NULL otherwise.  */
 459   lwp_info *filter_event (int lwpid, int wstat);
 460
 461   /* Wait for an event from child(ren) WAIT_PTID, and return any that
 462      match FILTER_PTID (leaving others pending).  The PTIDs can be:
 463      minus_one_ptid, to specify any child; a pid PTID, specifying all
 464      lwps of a thread group; or a PTID representing a single lwp.  Store
 465      the stop status through the status pointer WSTAT.  OPTIONS is
 466      passed to the waitpid call.  Return 0 if no event was found and
 467      OPTIONS contains WNOHANG.  Return -1 if no unwaited-for children
 468      was found.  Return the PID of the stopped child otherwise.  */
 469   int wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid,
 470                                int *wstatp, int options);
 471
 472   /* Wait for an event from child(ren) PTID.  PTIDs can be:
 473      minus_one_ptid, to specify any child; a pid PTID, specifying all
 474      lwps of a thread group; or a PTID representing a single lwp.  Store
 475      the stop status through the status pointer WSTAT.  OPTIONS is
 476      passed to the waitpid call.  Return 0 if no event was found and
 477      OPTIONS contains WNOHANG.  Return -1 if no unwaited-for children
 478      was found.  Return the PID of the stopped child otherwise.  */
 479   int wait_for_event (ptid_t ptid, int *wstatp, int options);
 480
 481   /* Wait for all children to stop for the SIGSTOPs we just queued.  */
 482   void wait_for_sigstop ();
 483
 484   /* Wait for process, returns status.  */
 485   ptid_t wait_1 (ptid_t ptid, target_waitstatus *ourstatus,
 486                  int target_options);
 487
 488   /* Stop all lwps that aren't stopped yet, except EXCEPT, if not NULL.
 489      If SUSPEND, then also increase the suspend count of every LWP,
 490      except EXCEPT.  */
 491   void stop_all_lwps (int suspend, lwp_info *except);
 492
 493   /* Stopped LWPs that the client wanted to be running, that don't have
 494      pending statuses, are set to run again, except for EXCEPT, if not
 495      NULL.  This undoes a stop_all_lwps call.  */
 496   void unstop_all_lwps (int unsuspend, lwp_info *except);
 497
 498   /* Start a step-over operation on LWP.  When LWP stopped at a
 499      breakpoint, to make progress, we need to remove the breakpoint out
 500      of the way.  If we let other threads run while we do that, they may
 501      pass by the breakpoint location and miss hitting it.  To avoid
 502      that, a step-over momentarily stops all threads while LWP is
 503      single-stepped by either hardware or software while the breakpoint
 504      is temporarily uninserted from the inferior.  When the single-step
 505      finishes, we reinsert the breakpoint, and let all threads that are
 506      supposed to be running, run again.  */
 507   void start_step_over (lwp_info *lwp);
 508
 509   /* If there's a step over in progress, wait until all threads stop
 510      (that is, until the stepping thread finishes its step), and
 511      unsuspend all lwps.  The stepping thread ends with its status
 512      pending, which is processed later when we get back to processing
 513      events.  */
 514   void complete_ongoing_step_over ();
 515
 516   /* When we finish a step-over, set threads running again.  If there's
 517      another thread that may need a step-over, now's the time to start
 518      it.  Eventually, we'll move all threads past their breakpoints.  */
 519   void proceed_all_lwps ();
 520
 521   /* The reason we resume in the caller, is because we want to be able
 522      to pass lwp->status_pending as WSTAT, and we need to clear
 523      status_pending_p before resuming, otherwise, resume_one_lwp
 524      refuses to resume.  */
 525   bool maybe_move_out_of_jump_pad (lwp_info *lwp, int *wstat);
 526
 527   /* Move THREAD out of the jump pad.  */
 528   void move_out_of_jump_pad (thread_info *thread);
 529
 530   /* Call low_arch_setup on THREAD.  */
 531   void arch_setup_thread (thread_info *thread);
 532
 533 #ifdef HAVE_LINUX_USRREGS
 534   /* Fetch one register.  */
 535   void fetch_register (const usrregs_info *usrregs, regcache *regcache,
 536                        int regno);
 537
 538   /* Store one register.  */
 539   void store_register (const usrregs_info *usrregs, regcache *regcache,
 540                        int regno);
 541 #endif
 542
 543   /* Fetch all registers, or just one, from the child process.
 544      If REGNO is -1, do this for all registers, skipping any that are
 545      assumed to have been retrieved by regsets_fetch_inferior_registers,
 546      unless ALL is non-zero.
 547      Otherwise, REGNO specifies which register (so we can save time).  */
 548   void usr_fetch_inferior_registers (const regs_info *regs_info,
 549                                      regcache *regcache, int regno, int all);
 550
 551   /* Store our register values back into the inferior.
 552      If REGNO is -1, do this for all registers, skipping any that are
 553      assumed to have been saved by regsets_store_inferior_registers,
 554      unless ALL is non-zero.
 555      Otherwise, REGNO specifies which register (so we can save time).  */
 556   void usr_store_inferior_registers (const regs_info *regs_info,
 557                                      regcache *regcache, int regno, int all);
 558
 559   /* Return the PC as read from the regcache of LWP, without any
 560      adjustment.  */
 561   CORE_ADDR get_pc (lwp_info *lwp);
 562
 563   /* Called when the LWP stopped for a signal/trap.  If it stopped for a
 564      trap check what caused it (breakpoint, watchpoint, trace, etc.),
 565      and save the result in the LWP's stop_reason field.  If it stopped
 566      for a breakpoint, decrement the PC if necessary on the lwp's
 567      architecture.  Returns true if we now have the LWP's stop PC.  */
 568   bool save_stop_reason (lwp_info *lwp);
 569
 570   /* Resume execution of LWP.  If STEP is nonzero, single-step it.  If
 571      SIGNAL is nonzero, give it that signal.  */
 572   void resume_one_lwp_throw (lwp_info *lwp, int step, int signal,
 573                              siginfo_t *info);
 574
 575   /* Like resume_one_lwp_throw, but no error is thrown if the LWP
 576      disappears while we try to resume it.  */
 577   void resume_one_lwp (lwp_info *lwp, int step, int signal, siginfo_t *info);
 578
 579   /* This function is called once per thread.  We check the thread's
 580      last resume request, which will tell us whether to resume, step, or
 581      leave the thread stopped.  Any signal the client requested to be
 582      delivered has already been enqueued at this point.
 583
 584      If any thread that GDB wants running is stopped at an internal
 585      breakpoint that needs stepping over, we start a step-over operation
 586      on that particular thread, and leave all others stopped.  */
 587   void proceed_one_lwp (thread_info *thread, lwp_info *except);
 588
 589   /* This function is called once per thread.  We check the thread's
 590      resume request, which will tell us whether to resume, step, or
 591      leave the thread stopped; and what signal, if any, it should be
 592      sent.
 593
 594      For threads which we aren't explicitly told otherwise, we preserve
 595      the stepping flag; this is used for stepping over gdbserver-placed
 596      breakpoints.
 597
 598      If pending_flags was set in any thread, we queue any needed
 599      signals, since we won't actually resume.  We already have a pending
 600      event to report, so we don't need to preserve any step requests;
 601      they should be re-issued if necessary.  */
 602   void resume_one_thread (thread_info *thread, bool leave_all_stopped);
 603
 604   /* Return true if this lwp has an interesting status pending.  */
 605   bool status_pending_p_callback (thread_info *thread, ptid_t ptid);
 606
 607   /* Resume LWPs that are currently stopped without any pending status
 608      to report, but are resumed from the core's perspective.  */
 609   void resume_stopped_resumed_lwps (thread_info *thread);
 610
 611   /* Unsuspend THREAD, except EXCEPT, and proceed.  */
 612   void unsuspend_and_proceed_one_lwp (thread_info *thread, lwp_info *except);
 613
 614   /* Return true if this lwp still has an interesting status pending.
 615      If not (e.g., it had stopped for a breakpoint that is gone), return
 616      false.  */
 617   bool thread_still_has_status_pending (thread_info *thread);
 618
 619   /* Return true if this lwp is to-be-resumed and has an interesting
 620      status pending.  */
 621   bool resume_status_pending (thread_info *thread);
 622
 623   /* Return true if this lwp that GDB wants running is stopped at an
 624      internal breakpoint that we need to step over.  It assumes that
 625      any required STOP_PC adjustment has already been propagated to
 626      the inferior's regcache.  */
 627   bool thread_needs_step_over (thread_info *thread);
 628
 629   /* Single step via hardware or software single step.
 630      Return 1 if hardware single stepping, 0 if software single stepping
 631      or can't single step.  */
 632   int single_step (lwp_info* lwp);
 633
 634   /* Install breakpoints for software single stepping.  */
 635   void install_software_single_step_breakpoints (lwp_info *lwp);
 636
 637 protected:
 638   /* The architecture-specific "low" methods are listed below.  */
 639
 640   /* Architecture-specific setup for the current thread.  */
 641   virtual void low_arch_setup () = 0;
 642
 643   /* Return false if we can fetch/store the register, true if we cannot
 644      fetch/store the register.  */
 645   virtual bool low_cannot_fetch_register (int regno) = 0;
 646
 647   virtual bool low_cannot_store_register (int regno) = 0;
 648
 649   /* Hook to fetch a register in some non-standard way.  Used for
 650      example by backends that have read-only registers with hardcoded
 651      values (e.g., IA64's gr0/fr0/fr1).  Returns true if register
 652      REGNO was supplied, false if not, and we should fallback to the
 653      standard ptrace methods.  */
 654   virtual bool low_fetch_register (regcache *regcache, int regno);
 655
 656   /* Return true if breakpoints are supported.  Such targets must
 657      implement the GET_PC and SET_PC methods.  */
 658   virtual bool low_supports_breakpoints ();
 659
 660   virtual CORE_ADDR low_get_pc (regcache *regcache);
 661
 662   virtual void low_set_pc (regcache *regcache, CORE_ADDR newpc);
 663
 664   /* Find the next possible PCs after the current instruction executes.
 665      Targets that override this method should also override
 666      'supports_software_single_step' to return true.  */
 667   virtual std::vector<CORE_ADDR> low_get_next_pcs (regcache *regcache);
 668
 669   /* How many bytes the PC should be decremented after a break.  */
 670   virtual int low_decr_pc_after_break ();
 671 };
 672
 673 extern linux_process_target *the_linux_target;
 674
 675 #define get_thread_lwp(thr) ((struct lwp_info *) (thread_target_data (thr)))
 676 #define get_lwp_thread(lwp) ((lwp)->thread)
 677
 678 /* This struct is recorded in the target_data field of struct thread_info.
 679
 680    On linux ``all_threads'' is keyed by the LWP ID, which we use as the
 681    GDB protocol representation of the thread ID.  Threads also have
 682    a "process ID" (poorly named) which is (presently) the same as the
 683    LWP ID.
 684
 685    There is also ``all_processes'' is keyed by the "overall process ID",
 686    which GNU/Linux calls tgid, "thread group ID".  */
 687
 688 struct lwp_info
 689 {
 690   /* Backlink to the parent object.  */
 691   struct thread_info *thread;
 692
 693   /* If this flag is set, the next SIGSTOP will be ignored (the
 694      process will be immediately resumed).  This means that either we
 695      sent the SIGSTOP to it ourselves and got some other pending event
 696      (so the SIGSTOP is still pending), or that we stopped the
 697      inferior implicitly via PTRACE_ATTACH and have not waited for it
 698      yet.  */
 699   int stop_expected;
 700
 701   /* When this is true, we shall not try to resume this thread, even
 702      if last_resume_kind isn't resume_stop.  */
 703   int suspended;
 704
 705   /* If this flag is set, the lwp is known to be stopped right now (stop
 706      event already received in a wait()).  */
 707   int stopped;
 708
 709   /* Signal whether we are in a SYSCALL_ENTRY or
 710      in a SYSCALL_RETURN event.
 711      Values:
 712      - TARGET_WAITKIND_SYSCALL_ENTRY
 713      - TARGET_WAITKIND_SYSCALL_RETURN */
 714   enum target_waitkind syscall_state;
 715
 716   /* When stopped is set, the last wait status recorded for this lwp.  */
 717   int last_status;
 718
 719   /* If WAITSTATUS->KIND != TARGET_WAITKIND_IGNORE, the waitstatus for
 720      this LWP's last event, to pass to GDB without any further
 721      processing.  This is used to store extended ptrace event
 722      information or exit status until it can be reported to GDB.  */
 723   struct target_waitstatus waitstatus;
 724
 725   /* A pointer to the fork child/parent relative.  Valid only while
 726      the parent fork event is not reported to higher layers.  Used to
 727      avoid wildcard vCont actions resuming a fork child before GDB is
 728      notified about the parent's fork event.  */
 729   struct lwp_info *fork_relative;
 730
 731   /* When stopped is set, this is where the lwp last stopped, with
 732      decr_pc_after_break already accounted for.  If the LWP is
 733      running, this is the address at which the lwp was resumed.  */
 734   CORE_ADDR stop_pc;
 735
 736   /* If this flag is set, STATUS_PENDING is a waitstatus that has not yet
 737      been reported.  */
 738   int status_pending_p;
 739   int status_pending;
 740
 741   /* The reason the LWP last stopped, if we need to track it
 742      (breakpoint, watchpoint, etc.)  */
 743   enum target_stop_reason stop_reason;
 744
 745   /* On architectures where it is possible to know the data address of
 746      a triggered watchpoint, STOPPED_DATA_ADDRESS is non-zero, and
 747      contains such data address.  Only valid if STOPPED_BY_WATCHPOINT
 748      is true.  */
 749   CORE_ADDR stopped_data_address;
 750
 751   /* If this is non-zero, it is a breakpoint to be reinserted at our next
 752      stop (SIGTRAP stops only).  */
 753   CORE_ADDR bp_reinsert;
 754
 755   /* If this flag is set, the last continue operation at the ptrace
 756      level on this process was a single-step.  */
 757   int stepping;
 758
 759   /* Range to single step within.  This is a copy of the step range
 760      passed along the last resume request.  See 'struct
 761      thread_resume'.  */
 762   CORE_ADDR step_range_start;   /* Inclusive */
 763   CORE_ADDR step_range_end;     /* Exclusive */
 764
 765   /* If this flag is set, we need to set the event request flags the
 766      next time we see this LWP stop.  */
 767   int must_set_ptrace_flags;
 768
 769   /* If this is non-zero, it points to a chain of signals which need to
 770      be delivered to this process.  */
 771   struct pending_signals *pending_signals;
 772
 773   /* A link used when resuming.  It is initialized from the resume request,
 774      and then processed and cleared in linux_resume_one_lwp.  */
 775   struct thread_resume *resume;
 776
 777   /* Information bout this lwp's fast tracepoint collection status (is it
 778      currently stopped in the jump pad, and if so, before or at/after the
 779      relocated instruction).  Normally, we won't care about this, but we will
 780      if a signal arrives to this lwp while it is collecting.  */
 781   fast_tpoint_collect_result collecting_fast_tracepoint;
 782
 783   /* If this is non-zero, it points to a chain of signals which need
 784      to be reported to GDB.  These were deferred because the thread
 785      was doing a fast tracepoint collect when they arrived.  */
 786   struct pending_signals *pending_signals_to_report;
 787
 788   /* When collecting_fast_tracepoint is first found to be 1, we insert
 789      a exit-jump-pad-quickly breakpoint.  This is it.  */
 790   struct breakpoint *exit_jump_pad_bkpt;
 791
 792 #ifdef USE_THREAD_DB
 793   int thread_known;
 794   /* The thread handle, used for e.g. TLS access.  Only valid if
 795      THREAD_KNOWN is set.  */
 796   td_thrhandle_t th;
 797
 798   /* The pthread_t handle.  */
 799   thread_t thread_handle;
 800 #endif
 801
 802   /* Arch-specific additions.  */
 803   struct arch_lwp_info *arch_private;
 804 };
 805
 806 int linux_pid_exe_is_elf_64_file (int pid, unsigned int *machine);
 807
 808 /* Attach to PTID.  Returns 0 on success, non-zero otherwise (an
 809    errno).  */
 810 int linux_attach_lwp (ptid_t ptid);
 811
 812 struct lwp_info *find_lwp_pid (ptid_t ptid);
 813 /* For linux_stop_lwp see nat/linux-nat.h.  */
 814
 815 #ifdef HAVE_LINUX_REGSETS
 816 void initialize_regsets_info (struct regsets_info *regsets_info);
 817 #endif
 818
 819 void initialize_low_arch (void);
 820
 821 void linux_set_pc_32bit (struct regcache *regcache, CORE_ADDR pc);
 822 CORE_ADDR linux_get_pc_32bit (struct regcache *regcache);
 823
 824 void linux_set_pc_64bit (struct regcache *regcache, CORE_ADDR pc);
 825 CORE_ADDR linux_get_pc_64bit (struct regcache *regcache);
 826
 827 /* From thread-db.c  */
 828 int thread_db_init (void);
 829 void thread_db_detach (struct process_info *);
 830 void thread_db_mourn (struct process_info *);
 831 int thread_db_handle_monitor_command (char *);
 832 int thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
 833                                CORE_ADDR load_module, CORE_ADDR *address);
 834 int thread_db_look_up_one_symbol (const char *name, CORE_ADDR *addrp);
 835
 836 /* Called from linux-low.c when a clone event is detected.  Upon entry,
 837    both the clone and the parent should be stopped.  This function does
 838    whatever is required have the clone under thread_db's control.  */
 839
 840 void thread_db_notice_clone (struct thread_info *parent_thr, ptid_t child_ptid);
 841
 842 bool thread_db_thread_handle (ptid_t ptid, gdb_byte **handle, int *handle_len);
 843
 844 extern int have_ptrace_getregset;
 845
 846 /* Search for the value with type MATCH in the auxv vector with
 847    entries of length WORDSIZE bytes.  If found, store the value in
 848    *VALP and return 1.  If not found or if there is an error, return
 849    0.  */
 850
 851 int linux_get_auxv (int wordsize, CORE_ADDR match,
 852                     CORE_ADDR *valp);
 853
 854 /* Fetch the AT_HWCAP entry from the auxv vector, where entries are length
 855    WORDSIZE.  If no entry was found, return zero.  */
 856
 857 CORE_ADDR linux_get_hwcap (int wordsize);
 858
 859 /* Fetch the AT_HWCAP2 entry from the auxv vector, where entries are length
 860    WORDSIZE.  If no entry was found, return zero.  */
 861
 862 CORE_ADDR linux_get_hwcap2 (int wordsize);
 863
 864 #endif /* GDBSERVER_LINUX_LOW_H */