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 (ptid_t ptid, struct target_waitstatus *ourstatus)
391 int status, save_errno;
399 pid = waitpid (ptid_get_pid (ptid), &status, 0);
402 while (pid == -1 && errno == EINTR);
404 clear_sigint_trap ();
408 fprintf_unfiltered (gdb_stderr,
409 _("Child process unexpectedly missing: %s.\n"),
410 safe_strerror (save_errno));
412 /* Claim it exited with unknown signal. */
413 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
414 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
415 return inferior_ptid;
418 /* Ignore terminated detached child processes. */
419 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
424 #ifdef PT_GET_PROCESS_STATE
425 if (WIFSTOPPED (status))
430 if (ptrace (PT_GET_PROCESS_STATE, pid,
431 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
432 perror_with_name (("ptrace"));
434 switch (pe.pe_report_event)
437 ourstatus->kind = TARGET_WAITKIND_FORKED;
438 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
440 /* Make sure the other end of the fork is stopped too. */
441 fpid = waitpid (pe.pe_other_pid, &status, 0);
443 perror_with_name (("waitpid"));
445 if (ptrace (PT_GET_PROCESS_STATE, fpid,
446 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
447 perror_with_name (("ptrace"));
449 gdb_assert (pe.pe_report_event == PTRACE_FORK);
450 gdb_assert (pe.pe_other_pid == pid);
451 if (fpid == ptid_get_pid (inferior_ptid))
453 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
454 return pid_to_ptid (fpid);
457 return pid_to_ptid (pid);
462 store_waitstatus (ourstatus, status);
463 return pid_to_ptid (pid);
466 /* Attempt a transfer all LEN bytes starting at OFFSET between the
467 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
468 Return the number of bytes actually transferred. */
471 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
472 const char *annex, gdb_byte *readbuf,
473 const gdb_byte *writebuf,
474 ULONGEST offset, LONGEST len)
476 pid_t pid = ptid_get_pid (inferior_ptid);
480 case TARGET_OBJECT_MEMORY:
482 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
483 request that promises to be much more efficient in reading
484 and writing data in the traced process's address space. */
486 struct ptrace_io_desc piod;
488 /* NOTE: We assume that there are no distinct address spaces
489 for instruction and data. However, on OpenBSD 3.9 and
490 later, PIOD_WRITE_D doesn't allow changing memory that's
491 mapped read-only. Since most code segments will be
492 read-only, using PIOD_WRITE_D will prevent us from
493 inserting breakpoints, so we use PIOD_WRITE_I instead. */
494 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
495 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
496 piod.piod_offs = (void *) (long) offset;
500 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
501 /* Return the actual number of bytes read or written. */
502 return piod.piod_len;
503 /* If the PT_IO request is somehow not supported, fallback on
504 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
505 to indicate failure. */
513 PTRACE_TYPE_RET word;
514 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
516 ULONGEST rounded_offset;
519 /* Round the start offset down to the next long word
521 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
523 /* Since ptrace will transfer a single word starting at that
524 rounded_offset the partial_len needs to be adjusted down to
525 that (remember this function only does a single transfer).
526 Should the required length be even less, adjust it down
528 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
529 if (partial_len > len)
534 /* If OFFSET:PARTIAL_LEN is smaller than
535 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
536 be needed. Read in the entire word. */
537 if (rounded_offset < offset
538 || (offset + partial_len
539 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
540 /* Need part of initial word -- fetch it. */
541 buffer.word = ptrace (PT_READ_I, pid,
542 (PTRACE_TYPE_ARG3)(uintptr_t)
545 /* Copy data to be written over corresponding part of
547 memcpy (buffer.byte + (offset - rounded_offset),
548 writebuf, partial_len);
551 ptrace (PT_WRITE_D, pid,
552 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
556 /* Using the appropriate one (I or D) is necessary for
557 Gould NP1, at least. */
559 ptrace (PT_WRITE_I, pid,
560 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
570 buffer.word = ptrace (PT_READ_I, pid,
571 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
575 /* Copy appropriate bytes out of the buffer. */
576 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
583 case TARGET_OBJECT_UNWIND_TABLE:
586 case TARGET_OBJECT_AUXV:
589 case TARGET_OBJECT_WCOOKIE:
597 /* Return non-zero if the thread specified by PTID is alive. */
600 inf_ptrace_thread_alive (ptid_t ptid)
602 /* ??? Is kill the right way to do this? */
603 return (kill (ptid_get_pid (ptid), 0) != -1);
606 /* Print status information about what we're accessing. */
609 inf_ptrace_files_info (struct target_ops *ignore)
611 struct inferior *inf = current_inferior ();
613 printf_filtered (_("\tUsing the running image of %s %s.\n"),
614 inf->attach_flag ? "attached" : "child",
615 target_pid_to_str (inferior_ptid));
618 /* Create a prototype ptrace target. The client can override it with
622 inf_ptrace_target (void)
624 struct target_ops *t = inf_child_target ();
626 t->to_attach = inf_ptrace_attach;
627 t->to_detach = inf_ptrace_detach;
628 t->to_resume = inf_ptrace_resume;
629 t->to_wait = inf_ptrace_wait;
630 t->to_files_info = inf_ptrace_files_info;
631 t->to_kill = inf_ptrace_kill;
632 t->to_create_inferior = inf_ptrace_create_inferior;
633 #ifdef PT_GET_PROCESS_STATE
634 t->to_follow_fork = inf_ptrace_follow_fork;
635 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
636 t->to_post_attach = inf_ptrace_post_attach;
638 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
639 t->to_thread_alive = inf_ptrace_thread_alive;
640 t->to_pid_to_str = normal_pid_to_str;
641 t->to_stop = inf_ptrace_stop;
642 t->to_xfer_partial = inf_ptrace_xfer_partial;
648 /* Pointer to a function that returns the offset within the user area
649 where a particular register is stored. */
650 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
652 /* Fetch register REGNUM from the inferior. */
655 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
657 struct gdbarch *gdbarch = get_regcache_arch (regcache);
660 PTRACE_TYPE_RET *buf;
663 /* This isn't really an address, but ptrace thinks of it as one. */
664 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
665 if (addr == (CORE_ADDR)-1
666 || gdbarch_cannot_fetch_register (gdbarch, regnum))
668 regcache_raw_supply (regcache, regnum, NULL);
672 /* Cater for systems like GNU/Linux, that implement threads as
673 separate processes. */
674 pid = ptid_get_lwp (inferior_ptid);
676 pid = ptid_get_pid (inferior_ptid);
678 size = register_size (gdbarch, regnum);
679 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
682 /* Read the register contents from the inferior a chunk at a time. */
683 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
686 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
688 error (_("Couldn't read register %s (#%d): %s."),
689 gdbarch_register_name (gdbarch, regnum),
690 regnum, safe_strerror (errno));
692 addr += sizeof (PTRACE_TYPE_RET);
694 regcache_raw_supply (regcache, regnum, buf);
697 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
698 for all registers. */
701 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
705 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
707 inf_ptrace_fetch_register (regcache, regnum);
709 inf_ptrace_fetch_register (regcache, regnum);
712 /* Store register REGNUM into the inferior. */
715 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
717 struct gdbarch *gdbarch = get_regcache_arch (regcache);
720 PTRACE_TYPE_RET *buf;
723 /* This isn't really an address, but ptrace thinks of it as one. */
724 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
725 if (addr == (CORE_ADDR)-1
726 || gdbarch_cannot_store_register (gdbarch, regnum))
729 /* Cater for systems like GNU/Linux, that implement threads as
730 separate processes. */
731 pid = ptid_get_lwp (inferior_ptid);
733 pid = ptid_get_pid (inferior_ptid);
735 size = register_size (gdbarch, regnum);
736 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
739 /* Write the register contents into the inferior a chunk at a time. */
740 regcache_raw_collect (regcache, regnum, buf);
741 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
744 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
746 error (_("Couldn't write register %s (#%d): %s."),
747 gdbarch_register_name (gdbarch, regnum),
748 regnum, safe_strerror (errno));
750 addr += sizeof (PTRACE_TYPE_RET);
754 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
755 this for all registers. */
758 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
762 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
764 inf_ptrace_store_register (regcache, regnum);
766 inf_ptrace_store_register (regcache, regnum);
769 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
770 a function returning the offset within the user area where a
771 particular register is stored. */
774 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
775 (struct gdbarch *, int, int))
777 struct target_ops *t = inf_ptrace_target();
779 gdb_assert (register_u_offset);
780 inf_ptrace_register_u_offset = register_u_offset;
781 t->to_fetch_registers = inf_ptrace_fetch_registers;
782 t->to_store_registers = inf_ptrace_store_registers;