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/>. */
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;
76 int attach_flag = find_inferior_pid (pid)->attach_flag;
78 struct thread_info *tp;
80 /* Otherwise, deleting the parent would get rid of this
82 last_tp->step_resume_breakpoint = NULL;
84 /* Before detaching from the parent, remove all breakpoints from
86 remove_breakpoints ();
88 if (ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
89 perror_with_name (("ptrace"));
91 /* Switch inferior_ptid out of the parent's way. */
92 inferior_ptid = pid_to_ptid (fpid);
94 /* Delete the parent. */
95 detach_inferior (pid);
98 inf = add_inferior (fpid);
99 inf->attach_flag = attach_flag;
100 tp = add_thread_silent (inferior_ptid);
102 tp->step_resume_breakpoint = step_resume_breakpoint;
103 tp->step_range_start = step_range_start;
104 tp->step_range_end = step_range_end;
105 tp->step_frame_id = step_frame_id;
107 /* Reset breakpoints in the child as appropriate. */
108 follow_inferior_reset_breakpoints ();
112 inferior_ptid = pid_to_ptid (pid);
113 detach_breakpoints (fpid);
115 if (ptrace (PT_DETACH, fpid, (PTRACE_TYPE_ARG3)1, 0) == -1)
116 perror_with_name (("ptrace"));
117 detach_inferior (pid);
123 #endif /* PT_GET_PROCESS_STATE */
126 /* Prepare to be traced. */
131 /* "Trace me, Dr. Memory!" */
132 ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
135 /* Start a new inferior Unix child process. EXEC_FILE is the file to
136 run, ALLARGS is a string containing the arguments to the program.
137 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
141 inf_ptrace_create_inferior (struct target_ops *ops,
142 char *exec_file, char *allargs, char **env,
147 pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
152 /* On some targets, there must be some explicit synchronization
153 between the parent and child processes after the debugger
154 forks, and before the child execs the debuggee program. This
155 call basically gives permission for the child to exec. */
157 target_acknowledge_created_inferior (pid);
159 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
160 be 1 or 2 depending on whether we're starting without or with a
162 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
164 /* On some targets, there must be some explicit actions taken after
165 the inferior has been started up. */
166 target_post_startup_inferior (pid_to_ptid (pid));
169 #ifdef PT_GET_PROCESS_STATE
172 inf_ptrace_post_startup_inferior (ptid_t pid)
176 /* Set the initial event mask. */
177 memset (&pe, 0, sizeof pe);
178 pe.pe_set_event |= PTRACE_FORK;
179 if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
180 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
181 perror_with_name (("ptrace"));
186 /* Clean up a rotting corpse of an inferior after it died. */
189 inf_ptrace_mourn_inferior (struct target_ops *ops)
193 /* Wait just one more time to collect the inferior's exit status.
194 Do not check whether this succeeds though, since we may be
195 dealing with a process that we attached to. Such a process will
196 only report its exit status to its original parent. */
197 waitpid (ptid_get_pid (inferior_ptid), &status, 0);
200 generic_mourn_inferior ();
203 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
204 be chatty about it. */
207 inf_ptrace_attach (struct target_ops *ops, char *args, int from_tty)
212 struct inferior *inf;
215 error_no_arg (_("process-id to attach"));
218 pid = strtol (args, &dummy, 0);
219 /* Some targets don't set errno on errors, grrr! */
220 if (pid == 0 && args == dummy)
221 error (_("Illegal process-id: %s."), args);
223 if (pid == getpid ()) /* Trying to masturbate? */
224 error (_("I refuse to debug myself!"));
228 exec_file = get_exec_file (0);
231 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
232 target_pid_to_str (pid_to_ptid (pid)));
234 printf_unfiltered (_("Attaching to %s\n"),
235 target_pid_to_str (pid_to_ptid (pid)));
237 gdb_flush (gdb_stdout);
242 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
244 perror_with_name (("ptrace"));
246 error (_("This system does not support attaching to a process"));
249 inferior_ptid = pid_to_ptid (pid);
251 inf = add_inferior (pid);
252 inf->attach_flag = 1;
254 /* Always add a main thread. If some target extends the ptrace
255 target, it should decorate the ptid later with more info. */
256 add_thread_silent (inferior_ptid);
261 #ifdef PT_GET_PROCESS_STATE
264 inf_ptrace_post_attach (int pid)
268 /* Set the initial event mask. */
269 memset (&pe, 0, sizeof pe);
270 pe.pe_set_event |= PTRACE_FORK;
271 if (ptrace (PT_SET_EVENT_MASK, pid,
272 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
273 perror_with_name (("ptrace"));
278 /* Detach from the inferior, optionally passing it the signal
279 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
282 inf_ptrace_detach (struct target_ops *ops, char *args, int from_tty)
284 pid_t pid = ptid_get_pid (inferior_ptid);
289 char *exec_file = get_exec_file (0);
292 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
293 target_pid_to_str (pid_to_ptid (pid)));
294 gdb_flush (gdb_stdout);
300 /* We'd better not have left any breakpoints in the program or it'll
301 die when it hits one. Also note that this may only work if we
302 previously attached to the inferior. It *might* work if we
303 started the process ourselves. */
305 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
307 perror_with_name (("ptrace"));
309 error (_("This system does not support detaching from a process"));
312 inferior_ptid = null_ptid;
313 detach_inferior (pid);
315 if (!have_inferiors ())
319 /* Kill the inferior. */
322 inf_ptrace_kill (void)
324 pid_t pid = ptid_get_pid (inferior_ptid);
330 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
331 waitpid (pid, &status, 0);
333 target_mourn_inferior ();
336 /* Stop the inferior. */
339 inf_ptrace_stop (ptid_t ptid)
341 /* Send a SIGINT to the process group. This acts just like the user
342 typed a ^C on the controlling terminal. Note that using a
343 negative process number in kill() is a System V-ism. The proper
344 BSD interface is killpg(). However, all modern BSDs support the
345 System V interface too. */
346 kill (-inferior_process_group, SIGINT);
349 /* Resume execution of thread PTID, or all threads if PTID is -1. If
350 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
354 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
356 pid_t pid = ptid_get_pid (ptid);
357 int request = PT_CONTINUE;
360 /* Resume all threads. Traditionally ptrace() only supports
361 single-threaded processes, so simply resume the inferior. */
362 pid = ptid_get_pid (inferior_ptid);
366 /* If this system does not support PT_STEP, a higher level
367 function will have called single_step() to transmute the step
368 request into a continue request (by setting breakpoints on
369 all possible successor instructions), so we don't have to
370 worry about that here. */
374 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
375 where it was. If GDB wanted it to start some other way, we have
376 already written a new program counter value to the child. */
378 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
380 perror_with_name (("ptrace"));
383 /* Wait for the child specified by PTID to do something. Return the
384 process ID of the child, or MINUS_ONE_PTID in case of error; store
385 the status in *OURSTATUS. */
388 inf_ptrace_wait (struct target_ops *ops,
389 ptid_t ptid, struct target_waitstatus *ourstatus)
392 int status, save_errno;
400 pid = waitpid (ptid_get_pid (ptid), &status, 0);
403 while (pid == -1 && errno == EINTR);
405 clear_sigint_trap ();
409 fprintf_unfiltered (gdb_stderr,
410 _("Child process unexpectedly missing: %s.\n"),
411 safe_strerror (save_errno));
413 /* Claim it exited with unknown signal. */
414 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
415 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
416 return inferior_ptid;
419 /* Ignore terminated detached child processes. */
420 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
425 #ifdef PT_GET_PROCESS_STATE
426 if (WIFSTOPPED (status))
431 if (ptrace (PT_GET_PROCESS_STATE, pid,
432 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
433 perror_with_name (("ptrace"));
435 switch (pe.pe_report_event)
438 ourstatus->kind = TARGET_WAITKIND_FORKED;
439 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
441 /* Make sure the other end of the fork is stopped too. */
442 fpid = waitpid (pe.pe_other_pid, &status, 0);
444 perror_with_name (("waitpid"));
446 if (ptrace (PT_GET_PROCESS_STATE, fpid,
447 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
448 perror_with_name (("ptrace"));
450 gdb_assert (pe.pe_report_event == PTRACE_FORK);
451 gdb_assert (pe.pe_other_pid == pid);
452 if (fpid == ptid_get_pid (inferior_ptid))
454 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
455 return pid_to_ptid (fpid);
458 return pid_to_ptid (pid);
463 store_waitstatus (ourstatus, status);
464 return pid_to_ptid (pid);
467 /* Attempt a transfer all LEN bytes starting at OFFSET between the
468 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
469 Return the number of bytes actually transferred. */
472 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
473 const char *annex, gdb_byte *readbuf,
474 const gdb_byte *writebuf,
475 ULONGEST offset, LONGEST len)
477 pid_t pid = ptid_get_pid (inferior_ptid);
481 case TARGET_OBJECT_MEMORY:
483 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
484 request that promises to be much more efficient in reading
485 and writing data in the traced process's address space. */
487 struct ptrace_io_desc piod;
489 /* NOTE: We assume that there are no distinct address spaces
490 for instruction and data. However, on OpenBSD 3.9 and
491 later, PIOD_WRITE_D doesn't allow changing memory that's
492 mapped read-only. Since most code segments will be
493 read-only, using PIOD_WRITE_D will prevent us from
494 inserting breakpoints, so we use PIOD_WRITE_I instead. */
495 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
496 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
497 piod.piod_offs = (void *) (long) offset;
501 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
502 /* Return the actual number of bytes read or written. */
503 return piod.piod_len;
504 /* If the PT_IO request is somehow not supported, fallback on
505 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
506 to indicate failure. */
514 PTRACE_TYPE_RET word;
515 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
517 ULONGEST rounded_offset;
520 /* Round the start offset down to the next long word
522 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
524 /* Since ptrace will transfer a single word starting at that
525 rounded_offset the partial_len needs to be adjusted down to
526 that (remember this function only does a single transfer).
527 Should the required length be even less, adjust it down
529 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
530 if (partial_len > len)
535 /* If OFFSET:PARTIAL_LEN is smaller than
536 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
537 be needed. Read in the entire word. */
538 if (rounded_offset < offset
539 || (offset + partial_len
540 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
541 /* Need part of initial word -- fetch it. */
542 buffer.word = ptrace (PT_READ_I, pid,
543 (PTRACE_TYPE_ARG3)(uintptr_t)
546 /* Copy data to be written over corresponding part of
548 memcpy (buffer.byte + (offset - rounded_offset),
549 writebuf, partial_len);
552 ptrace (PT_WRITE_D, pid,
553 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
557 /* Using the appropriate one (I or D) is necessary for
558 Gould NP1, at least. */
560 ptrace (PT_WRITE_I, pid,
561 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
571 buffer.word = ptrace (PT_READ_I, pid,
572 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
576 /* Copy appropriate bytes out of the buffer. */
577 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
584 case TARGET_OBJECT_UNWIND_TABLE:
587 case TARGET_OBJECT_AUXV:
590 case TARGET_OBJECT_WCOOKIE:
598 /* Return non-zero if the thread specified by PTID is alive. */
601 inf_ptrace_thread_alive (ptid_t ptid)
603 /* ??? Is kill the right way to do this? */
604 return (kill (ptid_get_pid (ptid), 0) != -1);
607 /* Print status information about what we're accessing. */
610 inf_ptrace_files_info (struct target_ops *ignore)
612 struct inferior *inf = current_inferior ();
614 printf_filtered (_("\tUsing the running image of %s %s.\n"),
615 inf->attach_flag ? "attached" : "child",
616 target_pid_to_str (inferior_ptid));
620 inf_ptrace_pid_to_str (struct target_ops *ops, ptid_t ptid)
622 return normal_pid_to_str (ptid);
625 /* Create a prototype ptrace target. The client can override it with
629 inf_ptrace_target (void)
631 struct target_ops *t = inf_child_target ();
633 t->to_attach = inf_ptrace_attach;
634 t->to_detach = inf_ptrace_detach;
635 t->to_resume = inf_ptrace_resume;
636 t->to_wait = inf_ptrace_wait;
637 t->to_files_info = inf_ptrace_files_info;
638 t->to_kill = inf_ptrace_kill;
639 t->to_create_inferior = inf_ptrace_create_inferior;
640 #ifdef PT_GET_PROCESS_STATE
641 t->to_follow_fork = inf_ptrace_follow_fork;
642 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
643 t->to_post_attach = inf_ptrace_post_attach;
645 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
646 t->to_thread_alive = inf_ptrace_thread_alive;
647 t->to_pid_to_str = inf_ptrace_pid_to_str;
648 t->to_stop = inf_ptrace_stop;
649 t->to_xfer_partial = inf_ptrace_xfer_partial;
655 /* Pointer to a function that returns the offset within the user area
656 where a particular register is stored. */
657 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
659 /* Fetch register REGNUM from the inferior. */
662 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
664 struct gdbarch *gdbarch = get_regcache_arch (regcache);
667 PTRACE_TYPE_RET *buf;
670 /* This isn't really an address, but ptrace thinks of it as one. */
671 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
672 if (addr == (CORE_ADDR)-1
673 || gdbarch_cannot_fetch_register (gdbarch, regnum))
675 regcache_raw_supply (regcache, regnum, NULL);
679 /* Cater for systems like GNU/Linux, that implement threads as
680 separate processes. */
681 pid = ptid_get_lwp (inferior_ptid);
683 pid = ptid_get_pid (inferior_ptid);
685 size = register_size (gdbarch, regnum);
686 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
689 /* Read the register contents from the inferior a chunk at a time. */
690 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
693 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
695 error (_("Couldn't read register %s (#%d): %s."),
696 gdbarch_register_name (gdbarch, regnum),
697 regnum, safe_strerror (errno));
699 addr += sizeof (PTRACE_TYPE_RET);
701 regcache_raw_supply (regcache, regnum, buf);
704 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
705 for all registers. */
708 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
712 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
714 inf_ptrace_fetch_register (regcache, regnum);
716 inf_ptrace_fetch_register (regcache, regnum);
719 /* Store register REGNUM into the inferior. */
722 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
724 struct gdbarch *gdbarch = get_regcache_arch (regcache);
727 PTRACE_TYPE_RET *buf;
730 /* This isn't really an address, but ptrace thinks of it as one. */
731 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
732 if (addr == (CORE_ADDR)-1
733 || gdbarch_cannot_store_register (gdbarch, regnum))
736 /* Cater for systems like GNU/Linux, that implement threads as
737 separate processes. */
738 pid = ptid_get_lwp (inferior_ptid);
740 pid = ptid_get_pid (inferior_ptid);
742 size = register_size (gdbarch, regnum);
743 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
746 /* Write the register contents into the inferior a chunk at a time. */
747 regcache_raw_collect (regcache, regnum, buf);
748 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
751 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
753 error (_("Couldn't write register %s (#%d): %s."),
754 gdbarch_register_name (gdbarch, regnum),
755 regnum, safe_strerror (errno));
757 addr += sizeof (PTRACE_TYPE_RET);
761 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
762 this for all registers. */
765 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
769 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
771 inf_ptrace_store_register (regcache, regnum);
773 inf_ptrace_store_register (regcache, regnum);
776 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
777 a function returning the offset within the user area where a
778 particular register is stored. */
781 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
782 (struct gdbarch *, int, int))
784 struct target_ops *t = inf_ptrace_target();
786 gdb_assert (register_u_offset);
787 inf_ptrace_register_u_offset = register_u_offset;
788 t->to_fetch_registers = inf_ptrace_fetch_registers;
789 t->to_store_registers = inf_ptrace_store_registers;