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
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/>. */
29 #include "gdb_assert.h"
30 #include "gdb_string.h"
31 #include "gdb_ptrace.h"
35 #include "inf-child.h"
36 #include "gdbthread.h"
40 #ifdef PT_GET_PROCESS_STATE
43 inf_ptrace_follow_fork (struct target_ops *ops, int follow_child)
47 struct thread_info *last_tp = NULL;
49 /* FIXME: kettenis/20050720: This stuff should really be passed as
50 an argument by our caller. */
53 struct target_waitstatus status;
55 get_last_target_status (&ptid, &status);
56 gdb_assert (status.kind == TARGET_WAITKIND_FORKED);
58 pid = ptid_get_pid (ptid);
59 last_tp = find_thread_pid (ptid);
62 if (ptrace (PT_GET_PROCESS_STATE, pid,
63 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
64 perror_with_name (("ptrace"));
66 gdb_assert (pe.pe_report_event == PTRACE_FORK);
67 fpid = pe.pe_other_pid;
71 /* Copy user stepping state to the new inferior thread. */
72 struct breakpoint *step_resume_breakpoint = last_tp->step_resume_breakpoint;
73 CORE_ADDR step_range_start = last_tp->step_range_start;
74 CORE_ADDR step_range_end = last_tp->step_range_end;
75 struct frame_id step_frame_id = last_tp->step_frame_id;
77 struct thread_info *tp;
79 /* Otherwise, deleting the parent would get rid of this
81 last_tp->step_resume_breakpoint = NULL;
83 /* Before detaching from the parent, remove all breakpoints from
85 detach_breakpoints (pid);
87 if (ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
88 perror_with_name (("ptrace"));
90 /* Switch inferior_ptid out of the parent's way. */
91 inferior_ptid = pid_to_ptid (fpid);
93 /* Delete the parent. */
94 detach_inferior (pid);
98 tp = add_thread_silent (inferior_ptid);
100 tp->step_resume_breakpoint = step_resume_breakpoint;
101 tp->step_range_start = step_range_start;
102 tp->step_range_end = step_range_end;
103 tp->step_frame_id = step_frame_id;
105 /* Reset breakpoints in the child as appropriate. */
106 follow_inferior_reset_breakpoints ();
110 inferior_ptid = pid_to_ptid (pid);
111 detach_breakpoints (fpid);
113 if (ptrace (PT_DETACH, fpid, (PTRACE_TYPE_ARG3)1, 0) == -1)
114 perror_with_name (("ptrace"));
115 detach_inferior (pid);
121 #endif /* PT_GET_PROCESS_STATE */
124 /* Prepare to be traced. */
129 /* "Trace me, Dr. Memory!" */
130 ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
133 /* Start a new inferior Unix child process. EXEC_FILE is the file to
134 run, ALLARGS is a string containing the arguments to the program.
135 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
139 inf_ptrace_create_inferior (struct target_ops *ops,
140 char *exec_file, char *allargs, char **env,
145 pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
150 /* On some targets, there must be some explicit synchronization
151 between the parent and child processes after the debugger
152 forks, and before the child execs the debuggee program. This
153 call basically gives permission for the child to exec. */
155 target_acknowledge_created_inferior (pid);
157 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
158 be 1 or 2 depending on whether we're starting without or with a
160 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
162 /* On some targets, there must be some explicit actions taken after
163 the inferior has been started up. */
164 target_post_startup_inferior (pid_to_ptid (pid));
167 #ifdef PT_GET_PROCESS_STATE
170 inf_ptrace_post_startup_inferior (ptid_t pid)
174 /* Set the initial event mask. */
175 memset (&pe, 0, sizeof pe);
176 pe.pe_set_event |= PTRACE_FORK;
177 if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
178 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
179 perror_with_name (("ptrace"));
184 /* Clean up a rotting corpse of an inferior after it died. */
187 inf_ptrace_mourn_inferior (struct target_ops *ops)
191 /* Wait just one more time to collect the inferior's exit status.
192 Do not check whether this succeeds though, since we may be
193 dealing with a process that we attached to. Such a process will
194 only report its exit status to its original parent. */
195 waitpid (ptid_get_pid (inferior_ptid), &status, 0);
198 generic_mourn_inferior ();
201 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
202 be chatty about it. */
205 inf_ptrace_attach (struct target_ops *ops, char *args, int from_tty)
210 struct inferior *inf;
213 error_no_arg (_("process-id to attach"));
216 pid = strtol (args, &dummy, 0);
217 /* Some targets don't set errno on errors, grrr! */
218 if (pid == 0 && args == dummy)
219 error (_("Illegal process-id: %s."), args);
221 if (pid == getpid ()) /* Trying to masturbate? */
222 error (_("I refuse to debug myself!"));
226 exec_file = get_exec_file (0);
229 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
230 target_pid_to_str (pid_to_ptid (pid)));
232 printf_unfiltered (_("Attaching to %s\n"),
233 target_pid_to_str (pid_to_ptid (pid)));
235 gdb_flush (gdb_stdout);
240 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
242 perror_with_name (("ptrace"));
244 error (_("This system does not support attaching to a process"));
247 inferior_ptid = pid_to_ptid (pid);
249 inf = add_inferior (pid);
250 inf->attach_flag = 1;
252 /* Always add a main thread. If some target extends the ptrace
253 target, it should decorate the ptid later with more info. */
254 add_thread_silent (inferior_ptid);
259 #ifdef PT_GET_PROCESS_STATE
262 inf_ptrace_post_attach (int pid)
266 /* Set the initial event mask. */
267 memset (&pe, 0, sizeof pe);
268 pe.pe_set_event |= PTRACE_FORK;
269 if (ptrace (PT_SET_EVENT_MASK, pid,
270 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
271 perror_with_name (("ptrace"));
276 /* Detach from the inferior, optionally passing it the signal
277 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
280 inf_ptrace_detach (struct target_ops *ops, char *args, int from_tty)
282 pid_t pid = ptid_get_pid (inferior_ptid);
287 char *exec_file = get_exec_file (0);
290 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
291 target_pid_to_str (pid_to_ptid (pid)));
292 gdb_flush (gdb_stdout);
298 /* We'd better not have left any breakpoints in the program or it'll
299 die when it hits one. Also note that this may only work if we
300 previously attached to the inferior. It *might* work if we
301 started the process ourselves. */
303 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
305 perror_with_name (("ptrace"));
307 error (_("This system does not support detaching from a process"));
310 inferior_ptid = null_ptid;
311 detach_inferior (pid);
315 /* Kill the inferior. */
318 inf_ptrace_kill (void)
320 pid_t pid = ptid_get_pid (inferior_ptid);
326 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
327 waitpid (pid, &status, 0);
329 target_mourn_inferior ();
332 /* Stop the inferior. */
335 inf_ptrace_stop (ptid_t ptid)
337 /* Send a SIGINT to the process group. This acts just like the user
338 typed a ^C on the controlling terminal. Note that using a
339 negative process number in kill() is a System V-ism. The proper
340 BSD interface is killpg(). However, all modern BSDs support the
341 System V interface too. */
342 kill (-inferior_process_group, SIGINT);
345 /* Resume execution of thread PTID, or all threads if PTID is -1. If
346 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
350 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
352 pid_t pid = ptid_get_pid (ptid);
353 int request = PT_CONTINUE;
356 /* Resume all threads. Traditionally ptrace() only supports
357 single-threaded processes, so simply resume the inferior. */
358 pid = ptid_get_pid (inferior_ptid);
362 /* If this system does not support PT_STEP, a higher level
363 function will have called single_step() to transmute the step
364 request into a continue request (by setting breakpoints on
365 all possible successor instructions), so we don't have to
366 worry about that here. */
370 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
371 where it was. If GDB wanted it to start some other way, we have
372 already written a new program counter value to the child. */
374 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
376 perror_with_name (("ptrace"));
379 /* Wait for the child specified by PTID to do something. Return the
380 process ID of the child, or MINUS_ONE_PTID in case of error; store
381 the status in *OURSTATUS. */
384 inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
387 int status, save_errno;
396 pid = waitpid (ptid_get_pid (ptid), &status, 0);
399 while (pid == -1 && errno == EINTR);
402 clear_sigint_trap ();
406 fprintf_unfiltered (gdb_stderr,
407 _("Child process unexpectedly missing: %s.\n"),
408 safe_strerror (save_errno));
410 /* Claim it exited with unknown signal. */
411 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
412 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
413 return minus_one_ptid;
416 /* Ignore terminated detached child processes. */
417 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
422 #ifdef PT_GET_PROCESS_STATE
423 if (WIFSTOPPED (status))
428 if (ptrace (PT_GET_PROCESS_STATE, pid,
429 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
430 perror_with_name (("ptrace"));
432 switch (pe.pe_report_event)
435 ourstatus->kind = TARGET_WAITKIND_FORKED;
436 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
438 /* Make sure the other end of the fork is stopped too. */
439 fpid = waitpid (pe.pe_other_pid, &status, 0);
441 perror_with_name (("waitpid"));
443 if (ptrace (PT_GET_PROCESS_STATE, fpid,
444 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
445 perror_with_name (("ptrace"));
447 gdb_assert (pe.pe_report_event == PTRACE_FORK);
448 gdb_assert (pe.pe_other_pid == pid);
449 if (fpid == ptid_get_pid (inferior_ptid))
451 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
452 return pid_to_ptid (fpid);
455 return pid_to_ptid (pid);
460 store_waitstatus (ourstatus, status);
461 return pid_to_ptid (pid);
464 /* Attempt a transfer all LEN bytes starting at OFFSET between the
465 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
466 Return the number of bytes actually transferred. */
469 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
470 const char *annex, gdb_byte *readbuf,
471 const gdb_byte *writebuf,
472 ULONGEST offset, LONGEST len)
474 pid_t pid = ptid_get_pid (inferior_ptid);
478 case TARGET_OBJECT_MEMORY:
480 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
481 request that promises to be much more efficient in reading
482 and writing data in the traced process's address space. */
484 struct ptrace_io_desc piod;
486 /* NOTE: We assume that there are no distinct address spaces
487 for instruction and data. However, on OpenBSD 3.9 and
488 later, PIOD_WRITE_D doesn't allow changing memory that's
489 mapped read-only. Since most code segments will be
490 read-only, using PIOD_WRITE_D will prevent us from
491 inserting breakpoints, so we use PIOD_WRITE_I instead. */
492 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
493 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
494 piod.piod_offs = (void *) (long) offset;
498 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
499 /* Return the actual number of bytes read or written. */
500 return piod.piod_len;
501 /* If the PT_IO request is somehow not supported, fallback on
502 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
503 to indicate failure. */
511 PTRACE_TYPE_RET word;
512 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
514 ULONGEST rounded_offset;
517 /* Round the start offset down to the next long word
519 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
521 /* Since ptrace will transfer a single word starting at that
522 rounded_offset the partial_len needs to be adjusted down to
523 that (remember this function only does a single transfer).
524 Should the required length be even less, adjust it down
526 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
527 if (partial_len > len)
532 /* If OFFSET:PARTIAL_LEN is smaller than
533 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
534 be needed. Read in the entire word. */
535 if (rounded_offset < offset
536 || (offset + partial_len
537 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
538 /* Need part of initial word -- fetch it. */
539 buffer.word = ptrace (PT_READ_I, pid,
540 (PTRACE_TYPE_ARG3)(uintptr_t)
543 /* Copy data to be written over corresponding part of
545 memcpy (buffer.byte + (offset - rounded_offset),
546 writebuf, partial_len);
549 ptrace (PT_WRITE_D, pid,
550 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
554 /* Using the appropriate one (I or D) is necessary for
555 Gould NP1, at least. */
557 ptrace (PT_WRITE_I, pid,
558 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
568 buffer.word = ptrace (PT_READ_I, pid,
569 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
573 /* Copy appropriate bytes out of the buffer. */
574 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
581 case TARGET_OBJECT_UNWIND_TABLE:
584 case TARGET_OBJECT_AUXV:
587 case TARGET_OBJECT_WCOOKIE:
595 /* Return non-zero if the thread specified by PTID is alive. */
598 inf_ptrace_thread_alive (ptid_t ptid)
600 /* ??? Is kill the right way to do this? */
601 return (kill (ptid_get_pid (ptid), 0) != -1);
604 /* Print status information about what we're accessing. */
607 inf_ptrace_files_info (struct target_ops *ignore)
609 struct inferior *inf = current_inferior ();
611 printf_filtered (_("\tUsing the running image of %s %s.\n"),
612 inf->attach_flag ? "attached" : "child",
613 target_pid_to_str (inferior_ptid));
616 /* Create a prototype ptrace target. The client can override it with
620 inf_ptrace_target (void)
622 struct target_ops *t = inf_child_target ();
624 t->to_attach = inf_ptrace_attach;
625 t->to_detach = inf_ptrace_detach;
626 t->to_resume = inf_ptrace_resume;
627 t->to_wait = inf_ptrace_wait;
628 t->to_files_info = inf_ptrace_files_info;
629 t->to_kill = inf_ptrace_kill;
630 t->to_create_inferior = inf_ptrace_create_inferior;
631 #ifdef PT_GET_PROCESS_STATE
632 t->to_follow_fork = inf_ptrace_follow_fork;
633 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
634 t->to_post_attach = inf_ptrace_post_attach;
636 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
637 t->to_thread_alive = inf_ptrace_thread_alive;
638 t->to_pid_to_str = normal_pid_to_str;
639 t->to_stop = inf_ptrace_stop;
640 t->to_xfer_partial = inf_ptrace_xfer_partial;
646 /* Pointer to a function that returns the offset within the user area
647 where a particular register is stored. */
648 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
650 /* Fetch register REGNUM from the inferior. */
653 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
655 struct gdbarch *gdbarch = get_regcache_arch (regcache);
658 PTRACE_TYPE_RET *buf;
661 /* This isn't really an address, but ptrace thinks of it as one. */
662 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
663 if (addr == (CORE_ADDR)-1
664 || gdbarch_cannot_fetch_register (gdbarch, regnum))
666 regcache_raw_supply (regcache, regnum, NULL);
670 /* Cater for systems like GNU/Linux, that implement threads as
671 separate processes. */
672 pid = ptid_get_lwp (inferior_ptid);
674 pid = ptid_get_pid (inferior_ptid);
676 size = register_size (gdbarch, regnum);
677 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
680 /* Read the register contents from the inferior a chunk at a time. */
681 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
684 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
686 error (_("Couldn't read register %s (#%d): %s."),
687 gdbarch_register_name (gdbarch, regnum),
688 regnum, safe_strerror (errno));
690 addr += sizeof (PTRACE_TYPE_RET);
692 regcache_raw_supply (regcache, regnum, buf);
695 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
696 for all registers. */
699 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
703 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
705 inf_ptrace_fetch_register (regcache, regnum);
707 inf_ptrace_fetch_register (regcache, regnum);
710 /* Store register REGNUM into the inferior. */
713 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
715 struct gdbarch *gdbarch = get_regcache_arch (regcache);
718 PTRACE_TYPE_RET *buf;
721 /* This isn't really an address, but ptrace thinks of it as one. */
722 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
723 if (addr == (CORE_ADDR)-1
724 || gdbarch_cannot_store_register (gdbarch, regnum))
727 /* Cater for systems like GNU/Linux, that implement threads as
728 separate processes. */
729 pid = ptid_get_lwp (inferior_ptid);
731 pid = ptid_get_pid (inferior_ptid);
733 size = register_size (gdbarch, regnum);
734 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
737 /* Write the register contents into the inferior a chunk at a time. */
738 regcache_raw_collect (regcache, regnum, buf);
739 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
742 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
744 error (_("Couldn't write register %s (#%d): %s."),
745 gdbarch_register_name (gdbarch, regnum),
746 regnum, safe_strerror (errno));
748 addr += sizeof (PTRACE_TYPE_RET);
752 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
753 this for all registers. */
756 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
760 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
762 inf_ptrace_store_register (regcache, regnum);
764 inf_ptrace_store_register (regcache, regnum);
767 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
768 a function returning the offset within the user area where a
769 particular register is stored. */
772 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
773 (struct gdbarch *, int, int))
775 struct target_ops *t = inf_ptrace_target();
777 gdb_assert (register_u_offset);
778 inf_ptrace_register_u_offset = register_u_offset;
779 t->to_fetch_registers = inf_ptrace_fetch_registers;
780 t->to_store_registers = inf_ptrace_store_registers;