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   /* Hooks to reformat register data for PEEKUSR/POKEUSR (in particular
 135      for registers smaller than an xfer unit).  */
 136   void (*collect_ptrace_register) (struct regcache *regcache,
 137                                    int regno, char *buf);
 138   void (*supply_ptrace_register) (struct regcache *regcache,
 139                                   int regno, const char *buf);
 140
 141   /* Hook to convert from target format to ptrace format and back.
 142      Returns true if any conversion was done; false otherwise.
 143      If DIRECTION is 1, then copy from INF to NATIVE.
 144      If DIRECTION is 0, copy from NATIVE to INF.  */
 145   int (*siginfo_fixup) (siginfo_t *native, gdb_byte *inf, int direction);
 146
 147   /* Hook to call when a new process is created or attached to.
 148      If extra per-process architecture-specific data is needed,
 149      allocate it here.  */
 150   struct arch_process_info * (*new_process) (void);
 151
 152   /* Hook to call when a process is being deleted.  If extra per-process
 153      architecture-specific data is needed, delete it here.  */
 154   void (*delete_process) (struct arch_process_info *info);
 155
 156   /* Hook to call when a new thread is detected.
 157      If extra per-thread architecture-specific data is needed,
 158      allocate it here.  */
 159   void (*new_thread) (struct lwp_info *);
 160
 161   /* Hook to call when a thread is being deleted.  If extra per-thread
 162      architecture-specific data is needed, delete it here.  */
 163   void (*delete_thread) (struct arch_lwp_info *);
 164
 165   /* Hook to call, if any, when a new fork is attached.  */
 166   void (*new_fork) (struct process_info *parent, struct process_info *child);
 167
 168   /* Hook to call prior to resuming a thread.  */
 169   void (*prepare_to_resume) (struct lwp_info *);
 170
 171   /* Hook to support target specific qSupported.  */
 172   void (*process_qsupported) (char **, int count);
 173
 174   /* Returns true if the low target supports tracepoints.  */
 175   int (*supports_tracepoints) (void);
 176
 177   /* Fill ADDRP with the thread area address of LWPID.  Returns 0 on
 178      success, -1 on failure.  */
 179   int (*get_thread_area) (int lwpid, CORE_ADDR *addrp);
 180
 181   /* Install a fast tracepoint jump pad.  See target.h for
 182      comments.  */
 183   int (*install_fast_tracepoint_jump_pad) (CORE_ADDR tpoint, CORE_ADDR tpaddr,
 184                                            CORE_ADDR collector,
 185                                            CORE_ADDR lockaddr,
 186                                            ULONGEST orig_size,
 187                                            CORE_ADDR *jump_entry,
 188                                            CORE_ADDR *trampoline,
 189                                            ULONGEST *trampoline_size,
 190                                            unsigned char *jjump_pad_insn,
 191                                            ULONGEST *jjump_pad_insn_size,
 192                                            CORE_ADDR *adjusted_insn_addr,
 193                                            CORE_ADDR *adjusted_insn_addr_end,
 194                                            char *err);
 195
 196   /* Return the bytecode operations vector for the current inferior.
 197      Returns NULL if bytecode compilation is not supported.  */
 198   struct emit_ops *(*emit_ops) (void);
 199
 200   /* Return the minimum length of an instruction that can be safely overwritten
 201      for use as a fast tracepoint.  */
 202   int (*get_min_fast_tracepoint_insn_len) (void);
 203
 204   /* Returns true if the low target supports range stepping.  */
 205   int (*supports_range_stepping) (void);
 206
 207   /* See target.h.  */
 208   int (*supports_hardware_single_step) (void);
 209
 210   /* Fill *SYSNO with the syscall nr trapped.  Only to be called when
 211      inferior is stopped due to SYSCALL_SIGTRAP.  */
 212   void (*get_syscall_trapinfo) (struct regcache *regcache, int *sysno);
 213
 214   /* See target.h.  */
 215   int (*get_ipa_tdesc_idx) (void);
 216 };
 217
 218 extern struct linux_target_ops the_low_target;
 219
 220 /* Target ops definitions for a Linux target.  */
 221
 222 class linux_process_target : public process_stratum_target
 223 {
 224 public:
 225
 226   int create_inferior (const char *program,
 227                        const std::vector<char *> &program_args) override;
 228
 229   void post_create_inferior () override;
 230
 231   int attach (unsigned long pid) override;
 232
 233   int kill (process_info *proc) override;
 234
 235   int detach (process_info *proc) override;
 236
 237   void mourn (process_info *proc) override;
 238
 239   void join (int pid) override;
 240
 241   bool thread_alive (ptid_t pid) override;
 242
 243   void resume (thread_resume *resume_info, size_t n) override;
 244
 245   ptid_t wait (ptid_t ptid, target_waitstatus *status,
 246                int options) override;
 247
 248   void fetch_registers (regcache *regcache, int regno) override;
 249
 250   void store_registers (regcache *regcache, int regno) override;
 251
 252   int prepare_to_access_memory () override;
 253
 254   void done_accessing_memory () override;
 255
 256   int read_memory (CORE_ADDR memaddr, unsigned char *myaddr,
 257                    int len) override;
 258
 259   int write_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 260                     int len) override;
 261
 262   void look_up_symbols () override;
 263
 264   void request_interrupt () override;
 265
 266   bool supports_read_auxv () override;
 267
 268   int read_auxv (CORE_ADDR offset, unsigned char *myaddr,
 269                  unsigned int len) override;
 270
 271   int insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
 272                     int size, raw_breakpoint *bp) override;
 273
 274   int remove_point (enum raw_bkpt_type type, CORE_ADDR addr,
 275                     int size, raw_breakpoint *bp) override;
 276
 277   bool stopped_by_sw_breakpoint () override;
 278
 279   bool supports_stopped_by_sw_breakpoint () override;
 280
 281   bool stopped_by_hw_breakpoint () override;
 282
 283   bool supports_stopped_by_hw_breakpoint () override;
 284
 285   bool supports_hardware_single_step () override;
 286
 287   bool stopped_by_watchpoint () override;
 288
 289   CORE_ADDR stopped_data_address () override;
 290
 291   bool supports_read_offsets () override;
 292
 293   int read_offsets (CORE_ADDR *text, CORE_ADDR *data) override;
 294
 295   bool supports_get_tls_address () override;
 296
 297   int get_tls_address (thread_info *thread, CORE_ADDR offset,
 298                        CORE_ADDR load_module, CORE_ADDR *address) override;
 299
 300   bool supports_qxfer_osdata () override;
 301
 302   int qxfer_osdata (const char *annex, unsigned char *readbuf,
 303                     unsigned const char *writebuf,
 304                     CORE_ADDR offset, int len) override;
 305
 306   bool supports_qxfer_siginfo () override;
 307
 308   int qxfer_siginfo (const char *annex, unsigned char *readbuf,
 309                      unsigned const char *writebuf,
 310                      CORE_ADDR offset, int len) override;
 311
 312   bool supports_non_stop () override;
 313
 314   bool async (bool enable) override;
 315
 316   int start_non_stop (bool enable) override;
 317
 318   bool supports_multi_process () override;
 319
 320   bool supports_fork_events () override;
 321
 322   bool supports_vfork_events () override;
 323
 324   bool supports_exec_events () override;
 325
 326   void handle_new_gdb_connection () override;
 327
 328   int handle_monitor_command (char *mon) override;
 329
 330   int core_of_thread (ptid_t ptid) override;
 331
 332 #if defined PT_GETDSBT || defined PTRACE_GETFDPIC
 333   bool supports_read_loadmap () override;
 334
 335   int read_loadmap (const char *annex, CORE_ADDR offset,
 336                     unsigned char *myaddr, unsigned int len) override;
 337 #endif
 338
 339   void process_qsupported (char **features, int count) override;
 340
 341   bool supports_tracepoints () override;
 342
 343   CORE_ADDR read_pc (regcache *regcache) override;
 344
 345   void write_pc (regcache *regcache, CORE_ADDR pc) override;
 346
 347   bool supports_thread_stopped () override;
 348
 349   bool thread_stopped (thread_info *thread) override;
 350
 351   void pause_all (bool freeze) override;
 352
 353   void unpause_all (bool unfreeze) override;
 354
 355   void stabilize_threads () override;
 356
 357   bool supports_fast_tracepoints () override;
 358
 359   int install_fast_tracepoint_jump_pad (CORE_ADDR tpoint,
 360                                         CORE_ADDR tpaddr,
 361                                         CORE_ADDR collector,
 362                                         CORE_ADDR lockaddr,
 363                                         ULONGEST orig_size,
 364                                         CORE_ADDR *jump_entry,
 365                                         CORE_ADDR *trampoline,
 366                                         ULONGEST *trampoline_size,
 367                                         unsigned char *jjump_pad_insn,
 368                                         ULONGEST *jjump_pad_insn_size,
 369                                         CORE_ADDR *adjusted_insn_addr,
 370                                         CORE_ADDR *adjusted_insn_addr_end,
 371                                         char *err) override;
 372
 373   int get_min_fast_tracepoint_insn_len () override;
 374
 375   struct emit_ops *emit_ops () override;
 376
 377   bool supports_disable_randomization () override;
 378
 379   bool supports_qxfer_libraries_svr4 () override;
 380
 381   int qxfer_libraries_svr4 (const char *annex,
 382                             unsigned char *readbuf,
 383                             unsigned const char *writebuf,
 384                             CORE_ADDR offset, int len) override;
 385
 386   bool supports_agent () override;
 387
 388 #ifdef HAVE_LINUX_BTRACE
 389   btrace_target_info *enable_btrace (ptid_t ptid,
 390                                      const btrace_config *conf) override;
 391
 392   int disable_btrace (btrace_target_info *tinfo) override;
 393
 394   int read_btrace (btrace_target_info *tinfo, buffer *buf,
 395                    enum btrace_read_type type) override;
 396
 397   int read_btrace_conf (const btrace_target_info *tinfo,
 398                         buffer *buf) override;
 399 #endif
 400
 401   bool supports_range_stepping () override;
 402
 403   bool supports_pid_to_exec_file () override;
 404
 405   char *pid_to_exec_file (int pid) override;
 406
 407   bool supports_multifs () override;
 408
 409   int multifs_open (int pid, const char *filename, int flags,
 410                     mode_t mode) override;
 411
 412   int multifs_unlink (int pid, const char *filename) override;
 413
 414   ssize_t multifs_readlink (int pid, const char *filename, char *buf,
 415                             size_t bufsiz) override;
 416
 417   const char *thread_name (ptid_t thread) override;
 418
 419 #if USE_THREAD_DB
 420   bool thread_handle (ptid_t ptid, gdb_byte **handle,
 421                       int *handle_len) override;
 422 #endif
 423
 424   bool supports_catch_syscall () override;
 425
 426   int get_ipa_tdesc_idx () override;
 427
 428   /* Return the information to access registers.  This has public
 429      visibility because proc-service uses it.  */
 430   virtual const regs_info *get_regs_info () = 0;
 431
 432 private:
 433
 434   /* Handle a GNU/Linux extended wait response.  If we see a clone,
 435      fork, or vfork event, we need to add the new LWP to our list
 436      (and return 0 so as not to report the trap to higher layers).
 437      If we see an exec event, we will modify ORIG_EVENT_LWP to point
 438      to a new LWP representing the new program.  */
 439   int handle_extended_wait (lwp_info **orig_event_lwp, int wstat);
 440
 441   /* Do low-level handling of the event, and check if we should go on
 442      and pass it to caller code.  Return the affected lwp if we are, or
 443      NULL otherwise.  */
 444   lwp_info *filter_event (int lwpid, int wstat);
 445
 446   /* Wait for an event from child(ren) WAIT_PTID, and return any that
 447      match FILTER_PTID (leaving others pending).  The PTIDs can be:
 448      minus_one_ptid, to specify any child; a pid PTID, specifying all
 449      lwps of a thread group; or a PTID representing a single lwp.  Store
 450      the stop status through the status pointer WSTAT.  OPTIONS is
 451      passed to the waitpid call.  Return 0 if no event was found and
 452      OPTIONS contains WNOHANG.  Return -1 if no unwaited-for children
 453      was found.  Return the PID of the stopped child otherwise.  */
 454   int wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid,
 455                                int *wstatp, int options);
 456
 457   /* Wait for an event from child(ren) PTID.  PTIDs can be:
 458      minus_one_ptid, to specify any child; a pid PTID, specifying all
 459      lwps of a thread group; or a PTID representing a single lwp.  Store
 460      the stop status through the status pointer WSTAT.  OPTIONS is
 461      passed to the waitpid call.  Return 0 if no event was found and
 462      OPTIONS contains WNOHANG.  Return -1 if no unwaited-for children
 463      was found.  Return the PID of the stopped child otherwise.  */
 464   int wait_for_event (ptid_t ptid, int *wstatp, int options);
 465
 466   /* Wait for all children to stop for the SIGSTOPs we just queued.  */
 467   void wait_for_sigstop ();
 468
 469   /* Wait for process, returns status.  */
 470   ptid_t wait_1 (ptid_t ptid, target_waitstatus *ourstatus,
 471                  int target_options);
 472
 473   /* Stop all lwps that aren't stopped yet, except EXCEPT, if not NULL.
 474      If SUSPEND, then also increase the suspend count of every LWP,
 475      except EXCEPT.  */
 476   void stop_all_lwps (int suspend, lwp_info *except);
 477
 478   /* Stopped LWPs that the client wanted to be running, that don't have
 479      pending statuses, are set to run again, except for EXCEPT, if not
 480      NULL.  This undoes a stop_all_lwps call.  */
 481   void unstop_all_lwps (int unsuspend, lwp_info *except);
 482
 483   /* Start a step-over operation on LWP.  When LWP stopped at a
 484      breakpoint, to make progress, we need to remove the breakpoint out
 485      of the way.  If we let other threads run while we do that, they may
 486      pass by the breakpoint location and miss hitting it.  To avoid
 487      that, a step-over momentarily stops all threads while LWP is
 488      single-stepped by either hardware or software while the breakpoint
 489      is temporarily uninserted from the inferior.  When the single-step
 490      finishes, we reinsert the breakpoint, and let all threads that are
 491      supposed to be running, run again.  */
 492   void start_step_over (lwp_info *lwp);
 493
 494   /* If there's a step over in progress, wait until all threads stop
 495      (that is, until the stepping thread finishes its step), and
 496      unsuspend all lwps.  The stepping thread ends with its status
 497      pending, which is processed later when we get back to processing
 498      events.  */
 499   void complete_ongoing_step_over ();
 500
 501   /* When we finish a step-over, set threads running again.  If there's
 502      another thread that may need a step-over, now's the time to start
 503      it.  Eventually, we'll move all threads past their breakpoints.  */
 504   void proceed_all_lwps ();
 505
 506   /* The reason we resume in the caller, is because we want to be able
 507      to pass lwp->status_pending as WSTAT, and we need to clear
 508      status_pending_p before resuming, otherwise, resume_one_lwp
 509      refuses to resume.  */
 510   bool maybe_move_out_of_jump_pad (lwp_info *lwp, int *wstat);
 511
 512   /* Move THREAD out of the jump pad.  */
 513   void move_out_of_jump_pad (thread_info *thread);
 514
 515   /* Call low_arch_setup on THREAD.  */
 516   void arch_setup_thread (thread_info *thread);
 517
 518 #ifdef HAVE_LINUX_USRREGS
 519   /* Fetch one register.  */
 520   void fetch_register (const usrregs_info *usrregs, regcache *regcache,
 521                        int regno);
 522
 523   /* Store one register.  */
 524   void store_register (const usrregs_info *usrregs, regcache *regcache,
 525                        int regno);
 526 #endif
 527
 528   /* Fetch all registers, or just one, from the child process.
 529      If REGNO is -1, do this for all registers, skipping any that are
 530      assumed to have been retrieved by regsets_fetch_inferior_registers,
 531      unless ALL is non-zero.
 532      Otherwise, REGNO specifies which register (so we can save time).  */
 533   void usr_fetch_inferior_registers (const regs_info *regs_info,
 534                                      regcache *regcache, int regno, int all);
 535
 536   /* Store our register values back into the inferior.
 537      If REGNO is -1, do this for all registers, skipping any that are
 538      assumed to have been saved by regsets_store_inferior_registers,
 539      unless ALL is non-zero.
 540      Otherwise, REGNO specifies which register (so we can save time).  */
 541   void usr_store_inferior_registers (const regs_info *regs_info,
 542                                      regcache *regcache, int regno, int all);
 543
 544   /* Return the PC as read from the regcache of LWP, without any
 545      adjustment.  */
 546   CORE_ADDR get_pc (lwp_info *lwp);
 547
 548   /* Called when the LWP stopped for a signal/trap.  If it stopped for a
 549      trap check what caused it (breakpoint, watchpoint, trace, etc.),
 550      and save the result in the LWP's stop_reason field.  If it stopped
 551      for a breakpoint, decrement the PC if necessary on the lwp's
 552      architecture.  Returns true if we now have the LWP's stop PC.  */
 553   bool save_stop_reason (lwp_info *lwp);
 554
 555   /* Resume execution of LWP.  If STEP is nonzero, single-step it.  If
 556      SIGNAL is nonzero, give it that signal.  */
 557   void resume_one_lwp_throw (lwp_info *lwp, int step, int signal,
 558                              siginfo_t *info);
 559
 560   /* Like resume_one_lwp_throw, but no error is thrown if the LWP
 561      disappears while we try to resume it.  */
 562   void resume_one_lwp (lwp_info *lwp, int step, int signal, siginfo_t *info);
 563
 564   /* This function is called once per thread.  We check the thread's
 565      last resume request, which will tell us whether to resume, step, or
 566      leave the thread stopped.  Any signal the client requested to be
 567      delivered has already been enqueued at this point.
 568
 569      If any thread that GDB wants running is stopped at an internal
 570      breakpoint that needs stepping over, we start a step-over operation
 571      on that particular thread, and leave all others stopped.  */
 572   void proceed_one_lwp (thread_info *thread, lwp_info *except);
 573
 574   /* This function is called once per thread.  We check the thread's
 575      resume request, which will tell us whether to resume, step, or
 576      leave the thread stopped; and what signal, if any, it should be
 577      sent.
 578
 579      For threads which we aren't explicitly told otherwise, we preserve
 580      the stepping flag; this is used for stepping over gdbserver-placed
 581      breakpoints.
 582
 583      If pending_flags was set in any thread, we queue any needed
 584      signals, since we won't actually resume.  We already have a pending
 585      event to report, so we don't need to preserve any step requests;
 586      they should be re-issued if necessary.  */
 587   void resume_one_thread (thread_info *thread, bool leave_all_stopped);
 588
 589   /* Return true if this lwp has an interesting status pending.  */
 590   bool status_pending_p_callback (thread_info *thread, ptid_t ptid);
 591
 592   /* Resume LWPs that are currently stopped without any pending status
 593      to report, but are resumed from the core's perspective.  */
 594   void resume_stopped_resumed_lwps (thread_info *thread);
 595
 596   /* Unsuspend THREAD, except EXCEPT, and proceed.  */
 597   void unsuspend_and_proceed_one_lwp (thread_info *thread, lwp_info *except);
 598
 599   /* Return true if this lwp still has an interesting status pending.
 600      If not (e.g., it had stopped for a breakpoint that is gone), return
 601      false.  */
 602   bool thread_still_has_status_pending (thread_info *thread);
 603
 604   /* Return true if this lwp is to-be-resumed and has an interesting
 605      status pending.  */
 606   bool resume_status_pending (thread_info *thread);
 607
 608   /* Return true if this lwp that GDB wants running is stopped at an
 609      internal breakpoint that we need to step over.  It assumes that
 610      any required STOP_PC adjustment has already been propagated to
 611      the inferior's regcache.  */
 612   bool thread_needs_step_over (thread_info *thread);
 613
 614   /* Single step via hardware or software single step.
 615      Return 1 if hardware single stepping, 0 if software single stepping
 616      or can't single step.  */
 617   int single_step (lwp_info* lwp);
 618
 619   /* Install breakpoints for software single stepping.  */
 620   void install_software_single_step_breakpoints (lwp_info *lwp);
 621
 622   /* Fetch the possibly triggered data watchpoint info and store it in
 623      CHILD.
 624
 625      On some archs, like x86, that use debug registers to set
 626      watchpoints, it's possible that the way to know which watched
 627      address trapped, is to check the register that is used to select
 628      which address to watch.  Problem is, between setting the watchpoint
 629      and reading back which data address trapped, the user may change
 630      the set of watchpoints, and, as a consequence, GDB changes the
 631      debug registers in the inferior.  To avoid reading back a stale
 632      stopped-data-address when that happens, we cache in LP the fact
 633      that a watchpoint trapped, and the corresponding data address, as
 634      soon as we see CHILD stop with a SIGTRAP.  If GDB changes the debug
 635      registers meanwhile, we have the cached data we can rely on.  */
 636   bool check_stopped_by_watchpoint (lwp_info *child);
 637
 638 protected:
 639   /* The architecture-specific "low" methods are listed below.  */
 640
 641   /* Architecture-specific setup for the current thread.  */
 642   virtual void low_arch_setup () = 0;
 643
 644   /* Return false if we can fetch/store the register, true if we cannot
 645      fetch/store the register.  */
 646   virtual bool low_cannot_fetch_register (int regno) = 0;
 647
 648   virtual bool low_cannot_store_register (int regno) = 0;
 649
 650   /* Hook to fetch a register in some non-standard way.  Used for
 651      example by backends that have read-only registers with hardcoded
 652      values (e.g., IA64's gr0/fr0/fr1).  Returns true if register
 653      REGNO was supplied, false if not, and we should fallback to the
 654      standard ptrace methods.  */
 655   virtual bool low_fetch_register (regcache *regcache, int regno);
 656
 657   /* Return true if breakpoints are supported.  Such targets must
 658      implement the GET_PC and SET_PC methods.  */
 659   virtual bool low_supports_breakpoints ();
 660
 661   virtual CORE_ADDR low_get_pc (regcache *regcache);
 662
 663   virtual void low_set_pc (regcache *regcache, CORE_ADDR newpc);
 664
 665   /* Find the next possible PCs after the current instruction executes.
 666      Targets that override this method should also override
 667      'supports_software_single_step' to return true.  */
 668   virtual std::vector<CORE_ADDR> low_get_next_pcs (regcache *regcache);
 669
 670   /* Return true if there is a breakpoint at PC.  */
 671   virtual bool low_breakpoint_at (CORE_ADDR pc) = 0;
 672
 673   /* Breakpoint and watchpoint related functions.  See target.h for
 674      comments.  */
 675   virtual int low_insert_point (raw_bkpt_type type, CORE_ADDR addr,
 676                                 int size, raw_breakpoint *bp);
 677
 678   virtual int low_remove_point (raw_bkpt_type type, CORE_ADDR addr,
 679                                 int size, raw_breakpoint *bp);
 680
 681   virtual bool low_stopped_by_watchpoint ();
 682
 683   virtual CORE_ADDR low_stopped_data_address ();
 684
 685   /* How many bytes the PC should be decremented after a break.  */
 686   virtual int low_decr_pc_after_break ();
 687 };
 688
 689 extern linux_process_target *the_linux_target;
 690
 691 #define get_thread_lwp(thr) ((struct lwp_info *) (thread_target_data (thr)))
 692 #define get_lwp_thread(lwp) ((lwp)->thread)
 693
 694 /* This struct is recorded in the target_data field of struct thread_info.
 695
 696    On linux ``all_threads'' is keyed by the LWP ID, which we use as the
 697    GDB protocol representation of the thread ID.  Threads also have
 698    a "process ID" (poorly named) which is (presently) the same as the
 699    LWP ID.
 700
 701    There is also ``all_processes'' is keyed by the "overall process ID",
 702    which GNU/Linux calls tgid, "thread group ID".  */
 703
 704 struct lwp_info
 705 {
 706   /* Backlink to the parent object.  */
 707   struct thread_info *thread;
 708
 709   /* If this flag is set, the next SIGSTOP will be ignored (the
 710      process will be immediately resumed).  This means that either we
 711      sent the SIGSTOP to it ourselves and got some other pending event
 712      (so the SIGSTOP is still pending), or that we stopped the
 713      inferior implicitly via PTRACE_ATTACH and have not waited for it
 714      yet.  */
 715   int stop_expected;
 716
 717   /* When this is true, we shall not try to resume this thread, even
 718      if last_resume_kind isn't resume_stop.  */
 719   int suspended;
 720
 721   /* If this flag is set, the lwp is known to be stopped right now (stop
 722      event already received in a wait()).  */
 723   int stopped;
 724
 725   /* Signal whether we are in a SYSCALL_ENTRY or
 726      in a SYSCALL_RETURN event.
 727      Values:
 728      - TARGET_WAITKIND_SYSCALL_ENTRY
 729      - TARGET_WAITKIND_SYSCALL_RETURN */
 730   enum target_waitkind syscall_state;
 731
 732   /* When stopped is set, the last wait status recorded for this lwp.  */
 733   int last_status;
 734
 735   /* If WAITSTATUS->KIND != TARGET_WAITKIND_IGNORE, the waitstatus for
 736      this LWP's last event, to pass to GDB without any further
 737      processing.  This is used to store extended ptrace event
 738      information or exit status until it can be reported to GDB.  */
 739   struct target_waitstatus waitstatus;
 740
 741   /* A pointer to the fork child/parent relative.  Valid only while
 742      the parent fork event is not reported to higher layers.  Used to
 743      avoid wildcard vCont actions resuming a fork child before GDB is
 744      notified about the parent's fork event.  */
 745   struct lwp_info *fork_relative;
 746
 747   /* When stopped is set, this is where the lwp last stopped, with
 748      decr_pc_after_break already accounted for.  If the LWP is
 749      running, this is the address at which the lwp was resumed.  */
 750   CORE_ADDR stop_pc;
 751
 752   /* If this flag is set, STATUS_PENDING is a waitstatus that has not yet
 753      been reported.  */
 754   int status_pending_p;
 755   int status_pending;
 756
 757   /* The reason the LWP last stopped, if we need to track it
 758      (breakpoint, watchpoint, etc.)  */
 759   enum target_stop_reason stop_reason;
 760
 761   /* On architectures where it is possible to know the data address of
 762      a triggered watchpoint, STOPPED_DATA_ADDRESS is non-zero, and
 763      contains such data address.  Only valid if STOPPED_BY_WATCHPOINT
 764      is true.  */
 765   CORE_ADDR stopped_data_address;
 766
 767   /* If this is non-zero, it is a breakpoint to be reinserted at our next
 768      stop (SIGTRAP stops only).  */
 769   CORE_ADDR bp_reinsert;
 770
 771   /* If this flag is set, the last continue operation at the ptrace
 772      level on this process was a single-step.  */
 773   int stepping;
 774
 775   /* Range to single step within.  This is a copy of the step range
 776      passed along the last resume request.  See 'struct
 777      thread_resume'.  */
 778   CORE_ADDR step_range_start;   /* Inclusive */
 779   CORE_ADDR step_range_end;     /* Exclusive */
 780
 781   /* If this flag is set, we need to set the event request flags the
 782      next time we see this LWP stop.  */
 783   int must_set_ptrace_flags;
 784
 785   /* If this is non-zero, it points to a chain of signals which need to
 786      be delivered to this process.  */
 787   struct pending_signals *pending_signals;
 788
 789   /* A link used when resuming.  It is initialized from the resume request,
 790      and then processed and cleared in linux_resume_one_lwp.  */
 791   struct thread_resume *resume;
 792
 793   /* Information bout this lwp's fast tracepoint collection status (is it
 794      currently stopped in the jump pad, and if so, before or at/after the
 795      relocated instruction).  Normally, we won't care about this, but we will
 796      if a signal arrives to this lwp while it is collecting.  */
 797   fast_tpoint_collect_result collecting_fast_tracepoint;
 798
 799   /* If this is non-zero, it points to a chain of signals which need
 800      to be reported to GDB.  These were deferred because the thread
 801      was doing a fast tracepoint collect when they arrived.  */
 802   struct pending_signals *pending_signals_to_report;
 803
 804   /* When collecting_fast_tracepoint is first found to be 1, we insert
 805      a exit-jump-pad-quickly breakpoint.  This is it.  */
 806   struct breakpoint *exit_jump_pad_bkpt;
 807
 808 #ifdef USE_THREAD_DB
 809   int thread_known;
 810   /* The thread handle, used for e.g. TLS access.  Only valid if
 811      THREAD_KNOWN is set.  */
 812   td_thrhandle_t th;
 813
 814   /* The pthread_t handle.  */
 815   thread_t thread_handle;
 816 #endif
 817
 818   /* Arch-specific additions.  */
 819   struct arch_lwp_info *arch_private;
 820 };
 821
 822 int linux_pid_exe_is_elf_64_file (int pid, unsigned int *machine);
 823
 824 /* Attach to PTID.  Returns 0 on success, non-zero otherwise (an
 825    errno).  */
 826 int linux_attach_lwp (ptid_t ptid);
 827
 828 struct lwp_info *find_lwp_pid (ptid_t ptid);
 829 /* For linux_stop_lwp see nat/linux-nat.h.  */
 830
 831 #ifdef HAVE_LINUX_REGSETS
 832 void initialize_regsets_info (struct regsets_info *regsets_info);
 833 #endif
 834
 835 void initialize_low_arch (void);
 836
 837 void linux_set_pc_32bit (struct regcache *regcache, CORE_ADDR pc);
 838 CORE_ADDR linux_get_pc_32bit (struct regcache *regcache);
 839
 840 void linux_set_pc_64bit (struct regcache *regcache, CORE_ADDR pc);
 841 CORE_ADDR linux_get_pc_64bit (struct regcache *regcache);
 842
 843 /* From thread-db.c  */
 844 int thread_db_init (void);
 845 void thread_db_detach (struct process_info *);
 846 void thread_db_mourn (struct process_info *);
 847 int thread_db_handle_monitor_command (char *);
 848 int thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
 849                                CORE_ADDR load_module, CORE_ADDR *address);
 850 int thread_db_look_up_one_symbol (const char *name, CORE_ADDR *addrp);
 851
 852 /* Called from linux-low.c when a clone event is detected.  Upon entry,
 853    both the clone and the parent should be stopped.  This function does
 854    whatever is required have the clone under thread_db's control.  */
 855
 856 void thread_db_notice_clone (struct thread_info *parent_thr, ptid_t child_ptid);
 857
 858 bool thread_db_thread_handle (ptid_t ptid, gdb_byte **handle, int *handle_len);
 859
 860 extern int have_ptrace_getregset;
 861
 862 /* Search for the value with type MATCH in the auxv vector with
 863    entries of length WORDSIZE bytes.  If found, store the value in
 864    *VALP and return 1.  If not found or if there is an error, return
 865    0.  */
 866
 867 int linux_get_auxv (int wordsize, CORE_ADDR match,
 868                     CORE_ADDR *valp);
 869
 870 /* Fetch the AT_HWCAP entry from the auxv vector, where entries are length
 871    WORDSIZE.  If no entry was found, return zero.  */
 872
 873 CORE_ADDR linux_get_hwcap (int wordsize);
 874
 875 /* Fetch the AT_HWCAP2 entry from the auxv vector, where entries are length
 876    WORDSIZE.  If no entry was found, return zero.  */
 877
 878 CORE_ADDR linux_get_hwcap2 (int wordsize);
 879
 880 #endif /* GDBSERVER_LINUX_LOW_H */