1 /* Low-level child interface to ptrace.
3 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,
4 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2007, 2008, 2009
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
30 #include "gdb_assert.h"
31 #include "gdb_string.h"
32 #include "gdb_ptrace.h"
36 #include "inf-ptrace.h"
37 #include "inf-child.h"
38 #include "gdbthread.h"
42 #ifdef PT_GET_PROCESS_STATE
45 inf_ptrace_follow_fork (struct target_ops *ops, int follow_child)
50 pid = ptid_get_pid (inferior_ptid);
52 if (ptrace (PT_GET_PROCESS_STATE, pid,
53 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
54 perror_with_name (("ptrace"));
56 gdb_assert (pe.pe_report_event == PTRACE_FORK);
57 fpid = pe.pe_other_pid;
61 struct inferior *parent_inf, *child_inf;
62 struct thread_info *tp;
64 parent_inf = find_inferior_pid (pid);
67 child_inf = add_inferior (fpid);
68 child_inf->attach_flag = parent_inf->attach_flag;
69 copy_terminal_info (child_inf, parent_inf);
71 /* Before detaching from the parent, remove all breakpoints from
73 remove_breakpoints ();
75 if (ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
76 perror_with_name (("ptrace"));
78 /* Switch inferior_ptid out of the parent's way. */
79 inferior_ptid = pid_to_ptid (fpid);
81 /* Delete the parent. */
82 detach_inferior (pid);
84 add_thread_silent (inferior_ptid);
88 /* Breakpoints have already been detached from the child by
91 if (ptrace (PT_DETACH, fpid, (PTRACE_TYPE_ARG3)1, 0) == -1)
92 perror_with_name (("ptrace"));
98 #endif /* PT_GET_PROCESS_STATE */
101 /* Prepare to be traced. */
106 /* "Trace me, Dr. Memory!" */
107 ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
110 /* Start a new inferior Unix child process. EXEC_FILE is the file to
111 run, ALLARGS is a string containing the arguments to the program.
112 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
116 inf_ptrace_create_inferior (struct target_ops *ops,
117 char *exec_file, char *allargs, char **env,
122 pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
127 /* On some targets, there must be some explicit synchronization
128 between the parent and child processes after the debugger
129 forks, and before the child execs the debuggee program. This
130 call basically gives permission for the child to exec. */
132 target_acknowledge_created_inferior (pid);
134 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
135 be 1 or 2 depending on whether we're starting without or with a
137 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
139 /* On some targets, there must be some explicit actions taken after
140 the inferior has been started up. */
141 target_post_startup_inferior (pid_to_ptid (pid));
144 #ifdef PT_GET_PROCESS_STATE
147 inf_ptrace_post_startup_inferior (ptid_t pid)
151 /* Set the initial event mask. */
152 memset (&pe, 0, sizeof pe);
153 pe.pe_set_event |= PTRACE_FORK;
154 if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
155 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
156 perror_with_name (("ptrace"));
161 /* Clean up a rotting corpse of an inferior after it died. */
164 inf_ptrace_mourn_inferior (struct target_ops *ops)
168 /* Wait just one more time to collect the inferior's exit status.
169 Do not check whether this succeeds though, since we may be
170 dealing with a process that we attached to. Such a process will
171 only report its exit status to its original parent. */
172 waitpid (ptid_get_pid (inferior_ptid), &status, 0);
174 generic_mourn_inferior ();
176 if (!have_inferiors ())
180 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
181 be chatty about it. */
184 inf_ptrace_attach (struct target_ops *ops, char *args, int from_tty)
189 struct inferior *inf;
192 error_no_arg (_("process-id to attach"));
195 pid = strtol (args, &dummy, 0);
196 /* Some targets don't set errno on errors, grrr! */
197 if (pid == 0 && args == dummy)
198 error (_("Illegal process-id: %s."), args);
200 if (pid == getpid ()) /* Trying to masturbate? */
201 error (_("I refuse to debug myself!"));
205 exec_file = get_exec_file (0);
208 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
209 target_pid_to_str (pid_to_ptid (pid)));
211 printf_unfiltered (_("Attaching to %s\n"),
212 target_pid_to_str (pid_to_ptid (pid)));
214 gdb_flush (gdb_stdout);
219 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
221 perror_with_name (("ptrace"));
223 error (_("This system does not support attaching to a process"));
226 inferior_ptid = pid_to_ptid (pid);
228 inf = add_inferior (pid);
229 inf->attach_flag = 1;
231 /* Always add a main thread. If some target extends the ptrace
232 target, it should decorate the ptid later with more info. */
233 add_thread_silent (inferior_ptid);
238 #ifdef PT_GET_PROCESS_STATE
241 inf_ptrace_post_attach (int pid)
245 /* Set the initial event mask. */
246 memset (&pe, 0, sizeof pe);
247 pe.pe_set_event |= PTRACE_FORK;
248 if (ptrace (PT_SET_EVENT_MASK, pid,
249 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
250 perror_with_name (("ptrace"));
255 /* Detach from the inferior, optionally passing it the signal
256 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
259 inf_ptrace_detach (struct target_ops *ops, char *args, int from_tty)
261 pid_t pid = ptid_get_pid (inferior_ptid);
266 char *exec_file = get_exec_file (0);
269 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
270 target_pid_to_str (pid_to_ptid (pid)));
271 gdb_flush (gdb_stdout);
277 /* We'd better not have left any breakpoints in the program or it'll
278 die when it hits one. Also note that this may only work if we
279 previously attached to the inferior. It *might* work if we
280 started the process ourselves. */
282 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
284 perror_with_name (("ptrace"));
286 error (_("This system does not support detaching from a process"));
289 inferior_ptid = null_ptid;
290 detach_inferior (pid);
292 if (!have_inferiors ())
296 /* Kill the inferior. */
299 inf_ptrace_kill (struct target_ops *ops)
301 pid_t pid = ptid_get_pid (inferior_ptid);
307 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
308 waitpid (pid, &status, 0);
310 target_mourn_inferior ();
313 /* Stop the inferior. */
316 inf_ptrace_stop (ptid_t ptid)
318 /* Send a SIGINT to the process group. This acts just like the user
319 typed a ^C on the controlling terminal. Note that using a
320 negative process number in kill() is a System V-ism. The proper
321 BSD interface is killpg(). However, all modern BSDs support the
322 System V interface too. */
323 kill (-inferior_process_group (), SIGINT);
326 /* Resume execution of thread PTID, or all threads if PTID is -1. If
327 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
331 inf_ptrace_resume (struct target_ops *ops,
332 ptid_t ptid, int step, enum target_signal signal)
334 pid_t pid = ptid_get_pid (ptid);
335 int request = PT_CONTINUE;
338 /* Resume all threads. Traditionally ptrace() only supports
339 single-threaded processes, so simply resume the inferior. */
340 pid = ptid_get_pid (inferior_ptid);
344 /* If this system does not support PT_STEP, a higher level
345 function will have called single_step() to transmute the step
346 request into a continue request (by setting breakpoints on
347 all possible successor instructions), so we don't have to
348 worry about that here. */
352 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
353 where it was. If GDB wanted it to start some other way, we have
354 already written a new program counter value to the child. */
356 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
358 perror_with_name (("ptrace"));
361 /* Wait for the child specified by PTID to do something. Return the
362 process ID of the child, or MINUS_ONE_PTID in case of error; store
363 the status in *OURSTATUS. */
366 inf_ptrace_wait (struct target_ops *ops,
367 ptid_t ptid, struct target_waitstatus *ourstatus, int options)
370 int status, save_errno;
378 pid = waitpid (ptid_get_pid (ptid), &status, 0);
381 while (pid == -1 && errno == EINTR);
383 clear_sigint_trap ();
387 fprintf_unfiltered (gdb_stderr,
388 _("Child process unexpectedly missing: %s.\n"),
389 safe_strerror (save_errno));
391 /* Claim it exited with unknown signal. */
392 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
393 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
394 return inferior_ptid;
397 /* Ignore terminated detached child processes. */
398 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
403 #ifdef PT_GET_PROCESS_STATE
404 if (WIFSTOPPED (status))
409 if (ptrace (PT_GET_PROCESS_STATE, pid,
410 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
411 perror_with_name (("ptrace"));
413 switch (pe.pe_report_event)
416 ourstatus->kind = TARGET_WAITKIND_FORKED;
417 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
419 /* Make sure the other end of the fork is stopped too. */
420 fpid = waitpid (pe.pe_other_pid, &status, 0);
422 perror_with_name (("waitpid"));
424 if (ptrace (PT_GET_PROCESS_STATE, fpid,
425 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
426 perror_with_name (("ptrace"));
428 gdb_assert (pe.pe_report_event == PTRACE_FORK);
429 gdb_assert (pe.pe_other_pid == pid);
430 if (fpid == ptid_get_pid (inferior_ptid))
432 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
433 return pid_to_ptid (fpid);
436 return pid_to_ptid (pid);
441 store_waitstatus (ourstatus, status);
442 return pid_to_ptid (pid);
445 /* Attempt a transfer all LEN bytes starting at OFFSET between the
446 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
447 Return the number of bytes actually transferred. */
450 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
451 const char *annex, gdb_byte *readbuf,
452 const gdb_byte *writebuf,
453 ULONGEST offset, LONGEST len)
455 pid_t pid = ptid_get_pid (inferior_ptid);
459 case TARGET_OBJECT_MEMORY:
461 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
462 request that promises to be much more efficient in reading
463 and writing data in the traced process's address space. */
465 struct ptrace_io_desc piod;
467 /* NOTE: We assume that there are no distinct address spaces
468 for instruction and data. However, on OpenBSD 3.9 and
469 later, PIOD_WRITE_D doesn't allow changing memory that's
470 mapped read-only. Since most code segments will be
471 read-only, using PIOD_WRITE_D will prevent us from
472 inserting breakpoints, so we use PIOD_WRITE_I instead. */
473 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
474 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
475 piod.piod_offs = (void *) (long) offset;
479 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
480 /* Return the actual number of bytes read or written. */
481 return piod.piod_len;
482 /* If the PT_IO request is somehow not supported, fallback on
483 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
484 to indicate failure. */
492 PTRACE_TYPE_RET word;
493 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
495 ULONGEST rounded_offset;
498 /* Round the start offset down to the next long word
500 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
502 /* Since ptrace will transfer a single word starting at that
503 rounded_offset the partial_len needs to be adjusted down to
504 that (remember this function only does a single transfer).
505 Should the required length be even less, adjust it down
507 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
508 if (partial_len > len)
513 /* If OFFSET:PARTIAL_LEN is smaller than
514 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
515 be needed. Read in the entire word. */
516 if (rounded_offset < offset
517 || (offset + partial_len
518 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
519 /* Need part of initial word -- fetch it. */
520 buffer.word = ptrace (PT_READ_I, pid,
521 (PTRACE_TYPE_ARG3)(uintptr_t)
524 /* Copy data to be written over corresponding part of
526 memcpy (buffer.byte + (offset - rounded_offset),
527 writebuf, partial_len);
530 ptrace (PT_WRITE_D, pid,
531 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
535 /* Using the appropriate one (I or D) is necessary for
536 Gould NP1, at least. */
538 ptrace (PT_WRITE_I, pid,
539 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
549 buffer.word = ptrace (PT_READ_I, pid,
550 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
554 /* Copy appropriate bytes out of the buffer. */
555 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
562 case TARGET_OBJECT_UNWIND_TABLE:
565 case TARGET_OBJECT_AUXV:
568 case TARGET_OBJECT_WCOOKIE:
576 /* Return non-zero if the thread specified by PTID is alive. */
579 inf_ptrace_thread_alive (struct target_ops *ops, ptid_t ptid)
581 /* ??? Is kill the right way to do this? */
582 return (kill (ptid_get_pid (ptid), 0) != -1);
585 /* Print status information about what we're accessing. */
588 inf_ptrace_files_info (struct target_ops *ignore)
590 struct inferior *inf = current_inferior ();
592 printf_filtered (_("\tUsing the running image of %s %s.\n"),
593 inf->attach_flag ? "attached" : "child",
594 target_pid_to_str (inferior_ptid));
598 inf_ptrace_pid_to_str (struct target_ops *ops, ptid_t ptid)
600 return normal_pid_to_str (ptid);
603 /* Create a prototype ptrace target. The client can override it with
607 inf_ptrace_target (void)
609 struct target_ops *t = inf_child_target ();
611 t->to_attach = inf_ptrace_attach;
612 t->to_detach = inf_ptrace_detach;
613 t->to_resume = inf_ptrace_resume;
614 t->to_wait = inf_ptrace_wait;
615 t->to_files_info = inf_ptrace_files_info;
616 t->to_kill = inf_ptrace_kill;
617 t->to_create_inferior = inf_ptrace_create_inferior;
618 #ifdef PT_GET_PROCESS_STATE
619 t->to_follow_fork = inf_ptrace_follow_fork;
620 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
621 t->to_post_attach = inf_ptrace_post_attach;
623 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
624 t->to_thread_alive = inf_ptrace_thread_alive;
625 t->to_pid_to_str = inf_ptrace_pid_to_str;
626 t->to_stop = inf_ptrace_stop;
627 t->to_xfer_partial = inf_ptrace_xfer_partial;
633 /* Pointer to a function that returns the offset within the user area
634 where a particular register is stored. */
635 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
637 /* Fetch register REGNUM from the inferior. */
640 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
642 struct gdbarch *gdbarch = get_regcache_arch (regcache);
645 PTRACE_TYPE_RET *buf;
648 /* This isn't really an address, but ptrace thinks of it as one. */
649 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
650 if (addr == (CORE_ADDR)-1
651 || gdbarch_cannot_fetch_register (gdbarch, regnum))
653 regcache_raw_supply (regcache, regnum, NULL);
657 /* Cater for systems like GNU/Linux, that implement threads as
658 separate processes. */
659 pid = ptid_get_lwp (inferior_ptid);
661 pid = ptid_get_pid (inferior_ptid);
663 size = register_size (gdbarch, regnum);
664 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
667 /* Read the register contents from the inferior a chunk at a time. */
668 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
671 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
673 error (_("Couldn't read register %s (#%d): %s."),
674 gdbarch_register_name (gdbarch, regnum),
675 regnum, safe_strerror (errno));
677 addr += sizeof (PTRACE_TYPE_RET);
679 regcache_raw_supply (regcache, regnum, buf);
682 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
683 for all registers. */
686 inf_ptrace_fetch_registers (struct target_ops *ops,
687 struct regcache *regcache, int regnum)
691 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
693 inf_ptrace_fetch_register (regcache, regnum);
695 inf_ptrace_fetch_register (regcache, regnum);
698 /* Store register REGNUM into the inferior. */
701 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
703 struct gdbarch *gdbarch = get_regcache_arch (regcache);
706 PTRACE_TYPE_RET *buf;
709 /* This isn't really an address, but ptrace thinks of it as one. */
710 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
711 if (addr == (CORE_ADDR)-1
712 || gdbarch_cannot_store_register (gdbarch, regnum))
715 /* Cater for systems like GNU/Linux, that implement threads as
716 separate processes. */
717 pid = ptid_get_lwp (inferior_ptid);
719 pid = ptid_get_pid (inferior_ptid);
721 size = register_size (gdbarch, regnum);
722 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
725 /* Write the register contents into the inferior a chunk at a time. */
726 regcache_raw_collect (regcache, regnum, buf);
727 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
730 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
732 error (_("Couldn't write register %s (#%d): %s."),
733 gdbarch_register_name (gdbarch, regnum),
734 regnum, safe_strerror (errno));
736 addr += sizeof (PTRACE_TYPE_RET);
740 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
741 this for all registers. */
744 inf_ptrace_store_registers (struct target_ops *ops,
745 struct regcache *regcache, int regnum)
749 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
751 inf_ptrace_store_register (regcache, regnum);
753 inf_ptrace_store_register (regcache, regnum);
756 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
757 a function returning the offset within the user area where a
758 particular register is stored. */
761 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
762 (struct gdbarch *, int, int))
764 struct target_ops *t = inf_ptrace_target();
766 gdb_assert (register_u_offset);
767 inf_ptrace_register_u_offset = register_u_offset;
768 t->to_fetch_registers = inf_ptrace_fetch_registers;
769 t->to_store_registers = inf_ptrace_store_registers;