1 /* Low-level child interface to ptrace.
3 Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
4 1998, 1999, 2000, 2001, 2002, 2004, 2005
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 2 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, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
32 #include "gdb_assert.h"
33 #include "gdb_string.h"
34 #include "gdb_ptrace.h"
38 #include "inf-child.h"
40 /* HACK: Save the ptrace ops returned by inf_ptrace_target. */
41 static struct target_ops
*ptrace_ops_hack
;
44 #ifdef PT_GET_PROCESS_STATE
47 inf_ptrace_follow_fork (int follow_child
)
52 /* FIXME: kettenis/20050720: This stuff should really be passed as
53 an argument by our caller. */
56 struct target_waitstatus status
;
58 get_last_target_status (&ptid
, &status
);
59 gdb_assert (status
.kind
== TARGET_WAITKIND_FORKED
);
61 pid
= ptid_get_pid (ptid
);
64 if (ptrace (PT_GET_PROCESS_STATE
, pid
,
65 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
66 perror_with_name (("ptrace"));
68 gdb_assert (pe
.pe_report_event
== PTRACE_FORK
);
69 fpid
= pe
.pe_other_pid
;
73 inferior_ptid
= pid_to_ptid (fpid
);
74 detach_breakpoints (pid
);
76 /* Reset breakpoints in the child as appropriate. */
77 follow_inferior_reset_breakpoints ();
79 if (ptrace (PT_DETACH
, pid
, (PTRACE_TYPE_ARG3
)1, 0) == -1)
80 perror_with_name (("ptrace"));
84 inferior_ptid
= pid_to_ptid (pid
);
85 detach_breakpoints (fpid
);
87 if (ptrace (PT_DETACH
, fpid
, (PTRACE_TYPE_ARG3
)1, 0) == -1)
88 perror_with_name (("ptrace"));
94 #endif /* PT_GET_PROCESS_STATE */
97 /* Prepare to be traced. */
102 /* "Trace me, Dr. Memory!" */
103 ptrace (PT_TRACE_ME
, 0, (PTRACE_TYPE_ARG3
)0, 0);
106 /* Start tracing PID. */
109 inf_ptrace_him (int pid
)
111 #ifdef PT_GET_PROCESS_STATE
115 /* Set the initial event mask. */
116 memset (&pe
, 0, sizeof pe
);
117 pe
.pe_set_event
|= PTRACE_FORK
;
118 if (ptrace (PT_SET_EVENT_MASK
, pid
,
119 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
120 perror_with_name (("ptrace"));
124 push_target (ptrace_ops_hack
);
126 /* On some targets, there must be some explicit synchronization
127 between the parent and child processes after the debugger
128 forks, and before the child execs the debuggee program. This
129 call basically gives permission for the child to exec. */
131 target_acknowledge_created_inferior (pid
);
133 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
134 be 1 or 2 depending on whether we're starting without or with a
136 startup_inferior (START_INFERIOR_TRAPS_EXPECTED
);
138 /* On some targets, there must be some explicit actions taken after
139 the inferior has been started up. */
140 target_post_startup_inferior (pid_to_ptid (pid
));
143 /* Start a new inferior Unix child process. EXEC_FILE is the file to
144 run, ALLARGS is a string containing the arguments to the program.
145 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
149 inf_ptrace_create_inferior (char *exec_file
, char *allargs
, char **env
,
152 fork_inferior (exec_file
, allargs
, env
, inf_ptrace_me
, inf_ptrace_him
,
155 /* We are at the first instruction we care about. */
156 observer_notify_inferior_created (¤t_target
, from_tty
);
158 /* Pedal to the metal... */
159 proceed ((CORE_ADDR
) -1, TARGET_SIGNAL_0
, 0);
162 /* Clean up a rotting corpse of an inferior after it died. */
165 inf_ptrace_mourn_inferior (void)
169 /* Wait just one more time to collect the inferior's exit status.
170 Don not check whether this succeeds though, since we may be
171 dealing with a process that we attached to. Such a process will
172 only report its exit status to its origional parent. */
173 waitpid (ptid_get_pid (inferior_ptid
), &status
, 0);
175 unpush_target (ptrace_ops_hack
);
176 generic_mourn_inferior ();
179 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
180 be chatty about it. */
183 inf_ptrace_attach (char *args
, int from_tty
)
190 error_no_arg (_("process-id to attach"));
193 pid
= strtol (args
, &dummy
, 0);
194 /* Some targets don't set errno on errors, grrr! */
195 if (pid
== 0 && args
== dummy
)
196 error (_("Illegal process-id: %s."), args
);
198 if (pid
== getpid ()) /* Trying to masturbate? */
199 error (_("I refuse to debug myself!"));
203 exec_file
= get_exec_file (0);
206 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file
,
207 target_pid_to_str (pid_to_ptid (pid
)));
209 printf_unfiltered (_("Attaching to %s\n"),
210 target_pid_to_str (pid_to_ptid (pid
)));
212 gdb_flush (gdb_stdout
);
217 ptrace (PT_ATTACH
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
219 perror_with_name (("ptrace"));
222 error (_("This system does not support attaching to a process"));
225 #ifdef PT_GET_PROCESS_STATE
229 /* Set the initial event mask. */
230 memset (&pe
, 0, sizeof pe
);
231 pe
.pe_set_event
|= PTRACE_FORK
;
232 if (ptrace (PT_SET_EVENT_MASK
, pid
,
233 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
234 perror_with_name (("ptrace"));
238 inferior_ptid
= pid_to_ptid (pid
);
239 push_target (ptrace_ops_hack
);
241 /* Do this first, before anything has had a chance to query the
242 inferior's symbol table or similar. */
243 observer_notify_inferior_created (¤t_target
, from_tty
);
246 /* Detach from the inferior, optionally passing it the signal
247 specified ARGS. If FROM_TTY is non-zero, be chatty about it. */
250 inf_ptrace_detach (char *args
, int from_tty
)
252 pid_t pid
= ptid_get_pid (inferior_ptid
);
257 char *exec_file
= get_exec_file (0);
260 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file
,
261 target_pid_to_str (pid_to_ptid (pid
)));
262 gdb_flush (gdb_stdout
);
268 /* We'd better not have left any breakpoints in the program or it'll
269 die when it hits one. Alsno note that this may only work if we
270 previously attached to the inferior. It *might* work if we
271 started the process ourselves. */
273 ptrace (PT_DETACH
, pid
, (PTRACE_TYPE_ARG3
)1, sig
);
275 perror_with_name (("ptrace"));
278 error (_("This system does not support detaching from a process"));
281 inferior_ptid
= null_ptid
;
282 unpush_target (ptrace_ops_hack
);
285 /* Kill the inferior. */
288 inf_ptrace_kill (void)
290 pid_t pid
= ptid_get_pid (inferior_ptid
);
296 ptrace (PT_KILL
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
297 waitpid (pid
, &status
, 0);
299 target_mourn_inferior ();
302 /* Stop the inferior. */
305 inf_ptrace_stop (void)
307 /* Send a SIGINT to the process group. This acts just like the user
308 typed a ^C on the controlling terminal. Note that using a
309 negative process number in kill() is a System V-ism. The proper
310 BSD interface is killpg(). However, all modern BSDs support the
311 System V interface too. */
312 kill (-inferior_process_group
, SIGINT
);
315 /* Resume execution of thread PTID, or all threads if PTID is -1. If
316 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
320 inf_ptrace_resume (ptid_t ptid
, int step
, enum target_signal signal
)
322 pid_t pid
= ptid_get_pid (ptid
);
323 int request
= PT_CONTINUE
;
326 /* Resume all threads. Traditionally ptrace() only supports
327 single-threaded processes, so simply resume the inferior. */
328 pid
= ptid_get_pid (inferior_ptid
);
332 /* If this system does not support PT_STEP, a higher level
333 function will have called single_step() to transmute the step
334 request into a continue request (by setting breakpoints on
335 all possible successor instructions), so we don't have to
336 worry about that here. */
340 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
341 where it was. If GDB wanted it to start some other way, we have
342 already written a new program counter value to the child. */
344 ptrace (request
, pid
, (PTRACE_TYPE_ARG3
)1, target_signal_to_host (signal
));
346 perror_with_name (("ptrace"));
349 /* Wait for the child specified by PTID to do something. Return the
350 process ID of the child, or MINUS_ONE_PTID in case of error; store
351 the status in *OURSTATUS. */
354 inf_ptrace_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
357 int status
, save_errno
;
366 pid
= waitpid (ptid_get_pid (ptid
), &status
, 0);
369 while (pid
== -1 && errno
== EINTR
);
372 clear_sigint_trap ();
376 fprintf_unfiltered (gdb_stderr
,
377 _("Child process unexpectedly missing: %s.\n"),
378 safe_strerror (save_errno
));
380 /* Claim it exited with unknown signal. */
381 ourstatus
->kind
= TARGET_WAITKIND_SIGNALLED
;
382 ourstatus
->value
.sig
= TARGET_SIGNAL_UNKNOWN
;
383 return minus_one_ptid
;
386 /* Ignore terminated detached child processes. */
387 if (!WIFSTOPPED (status
) && pid
!= ptid_get_pid (inferior_ptid
))
392 #ifdef PT_GET_PROCESS_STATE
393 if (WIFSTOPPED (status
))
398 if (ptrace (PT_GET_PROCESS_STATE
, pid
,
399 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
400 perror_with_name (("ptrace"));
402 switch (pe
.pe_report_event
)
405 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
406 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
408 /* Make sure the other end of the fork is stopped too. */
409 fpid
= waitpid (pe
.pe_other_pid
, &status
, 0);
411 perror_with_name (("waitpid"));
413 if (ptrace (PT_GET_PROCESS_STATE
, fpid
,
414 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
415 perror_with_name (("ptrace"));
417 gdb_assert (pe
.pe_report_event
== PTRACE_FORK
);
418 gdb_assert (pe
.pe_other_pid
== pid
);
419 if (fpid
== ptid_get_pid (inferior_ptid
))
421 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
422 return pid_to_ptid (fpid
);
425 return pid_to_ptid (pid
);
430 store_waitstatus (ourstatus
, status
);
431 return pid_to_ptid (pid
);
434 /* Attempt a transfer all LEN bytes starting at OFFSET between the
435 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
436 Return the number of bytes actually transferred. */
439 inf_ptrace_xfer_partial (struct target_ops
*ops
, enum target_object object
,
440 const char *annex
, gdb_byte
*readbuf
,
441 const gdb_byte
*writebuf
,
442 ULONGEST offset
, LONGEST len
)
444 pid_t pid
= ptid_get_pid (inferior_ptid
);
448 case TARGET_OBJECT_MEMORY
:
450 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
451 request that promises to be much more efficient in reading
452 and writing data in the traced process's address space. */
454 struct ptrace_io_desc piod
;
456 /* NOTE: We assume that there are no distinct address spaces
457 for instruction and data. */
458 piod
.piod_op
= writebuf
? PIOD_WRITE_D
: PIOD_READ_D
;
459 piod
.piod_addr
= writebuf
? (void *) writebuf
: readbuf
;
460 piod
.piod_offs
= (void *) (long) offset
;
464 if (ptrace (PT_IO
, pid
, (caddr_t
)&piod
, 0) == 0)
465 /* Return the actual number of bytes read or written. */
466 return piod
.piod_len
;
467 /* If the PT_IO request is somehow not supported, fallback on
468 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
469 to indicate failure. */
477 PTRACE_TYPE_RET word
;
478 gdb_byte byte
[sizeof (PTRACE_TYPE_RET
)];
480 ULONGEST rounded_offset
;
483 /* Round the start offset down to the next long word
485 rounded_offset
= offset
& -(ULONGEST
) sizeof (PTRACE_TYPE_RET
);
487 /* Since ptrace will transfer a single word starting at that
488 rounded_offset the partial_len needs to be adjusted down to
489 that (remember this function only does a single transfer).
490 Should the required length be even less, adjust it down
492 partial_len
= (rounded_offset
+ sizeof (PTRACE_TYPE_RET
)) - offset
;
493 if (partial_len
> len
)
498 /* If OFFSET:PARTIAL_LEN is smaller than
499 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
500 be needed. Read in the entire word. */
501 if (rounded_offset
< offset
502 || (offset
+ partial_len
503 < rounded_offset
+ sizeof (PTRACE_TYPE_RET
)))
504 /* Need part of initial word -- fetch it. */
505 buffer
.word
= ptrace (PT_READ_I
, pid
,
506 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, 0);
508 /* Copy data to be written over corresponding part of
510 memcpy (buffer
.byte
+ (offset
- rounded_offset
),
511 writebuf
, partial_len
);
514 ptrace (PT_WRITE_D
, pid
,
515 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, buffer
.word
);
518 /* Using the appropriate one (I or D) is necessary for
519 Gould NP1, at least. */
521 ptrace (PT_WRITE_I
, pid
,
522 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, buffer
.word
);
531 buffer
.word
= ptrace (PT_READ_I
, pid
,
532 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, 0);
535 /* Copy appropriate bytes out of the buffer. */
536 memcpy (readbuf
, buffer
.byte
+ (offset
- rounded_offset
),
543 case TARGET_OBJECT_UNWIND_TABLE
:
546 case TARGET_OBJECT_AUXV
:
549 case TARGET_OBJECT_WCOOKIE
:
557 /* Return non-zero if the thread specified by PTID is alive. */
560 inf_ptrace_thread_alive (ptid_t ptid
)
562 /* ??? Is kill the right way to do this? */
563 return (kill (ptid_get_pid (ptid
), 0) != -1);
566 /* Print status information about what we're accessing. */
569 inf_ptrace_files_info (struct target_ops
*ignore
)
571 printf_filtered (_("\tUsing the running image of %s %s.\n"),
572 attach_flag
? "attached" : "child",
573 target_pid_to_str (inferior_ptid
));
576 /* Create a prototype ptrace target. The client can override it with
580 inf_ptrace_target (void)
582 struct target_ops
*t
= inf_child_target ();
584 t
->to_attach
= inf_ptrace_attach
;
585 t
->to_detach
= inf_ptrace_detach
;
586 t
->to_resume
= inf_ptrace_resume
;
587 t
->to_wait
= inf_ptrace_wait
;
588 t
->to_files_info
= inf_ptrace_files_info
;
589 t
->to_kill
= inf_ptrace_kill
;
590 t
->to_create_inferior
= inf_ptrace_create_inferior
;
591 #ifdef PT_GET_PROCESS_STATE
592 t
->to_follow_fork
= inf_ptrace_follow_fork
;
594 t
->to_mourn_inferior
= inf_ptrace_mourn_inferior
;
595 t
->to_thread_alive
= inf_ptrace_thread_alive
;
596 t
->to_pid_to_str
= normal_pid_to_str
;
597 t
->to_stop
= inf_ptrace_stop
;
598 t
->to_xfer_partial
= inf_ptrace_xfer_partial
;
605 /* Pointer to a function that returns the offset within the user area
606 where a particular register is stored. */
607 static CORE_ADDR (*inf_ptrace_register_u_offset
)(int);
609 /* Fetch register REGNUM from the inferior. */
612 inf_ptrace_fetch_register (int regnum
)
616 PTRACE_TYPE_RET
*buf
;
619 /* Cater for systems like GNU/Linux, that implement threads as
620 seperate processes. */
621 pid
= ptid_get_lwp (inferior_ptid
);
623 pid
= ptid_get_pid (inferior_ptid
);
625 /* This isn't really an address, but ptrace thinks of it as one. */
626 addr
= inf_ptrace_register_u_offset (regnum
);
627 size
= register_size (current_gdbarch
, regnum
);
629 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
632 /* Read the register contents from the inferior a chuck at the time. */
633 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
636 buf
[i
] = ptrace (PT_READ_U
, pid
, (PTRACE_TYPE_ARG3
)addr
, 0);
638 error (_("Couldn't read register %s (#%d): %s."),
639 REGISTER_NAME (regnum
), regnum
, safe_strerror (errno
));
641 addr
+= sizeof (PTRACE_TYPE_RET
);
643 regcache_raw_supply (current_regcache
, regnum
, buf
);
646 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
647 for all registers. */
650 inf_ptrace_fetch_registers (int regnum
)
653 for (regnum
= 0; regnum
< NUM_REGS
; regnum
++)
654 inf_ptrace_fetch_register (regnum
);
656 inf_ptrace_fetch_register (regnum
);
659 /* Store register REGNUM into the inferior. */
662 inf_ptrace_store_register (int regnum
)
666 PTRACE_TYPE_RET
*buf
;
669 /* Cater for systems like GNU/Linux, that implement threads as
670 seperate processes. */
671 pid
= ptid_get_lwp (inferior_ptid
);
673 pid
= ptid_get_pid (inferior_ptid
);
675 /* This isn't really an address, but ptrace thinks of it as one. */
676 addr
= inf_ptrace_register_u_offset (regnum
);
677 size
= register_size (current_gdbarch
, regnum
);
679 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
682 /* Write the register contents into the inferior a chunk at the time. */
683 regcache_raw_collect (current_regcache
, regnum
, buf
);
684 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
687 ptrace (PT_WRITE_U
, pid
, (PTRACE_TYPE_ARG3
)addr
, buf
[i
]);
689 error (_("Couldn't write register %s (#%d): %s."),
690 REGISTER_NAME (regnum
), regnum
, safe_strerror (errno
));
692 addr
+= sizeof (PTRACE_TYPE_RET
);
696 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
697 this for all registers. */
700 inf_ptrace_store_registers (int regnum
)
703 for (regnum
= 0; regnum
< NUM_REGS
; regnum
++)
704 inf_ptrace_store_register (regnum
);
706 inf_ptrace_store_register (regnum
);
709 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
710 a function returning the offset within the user area where a
711 particular register is stored. */
714 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset
)(int))
716 struct target_ops
*t
= inf_ptrace_target();
718 gdb_assert (register_u_offset
);
719 inf_ptrace_register_u_offset
= register_u_offset
;
720 t
->to_fetch_registers
= inf_ptrace_fetch_registers
;
721 t
->to_store_registers
= inf_ptrace_store_registers
;