1 /* Low-level child interface to ptrace.
3 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
4 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2006
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., 51 Franklin Street, Fifth Floor,
22 Boston, MA 02110-1301, 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 (struct target_ops
*ops
, 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 push_target (ptrace_ops_hack
);
113 /* On some targets, there must be some explicit synchronization
114 between the parent and child processes after the debugger
115 forks, and before the child execs the debuggee program. This
116 call basically gives permission for the child to exec. */
118 target_acknowledge_created_inferior (pid
);
120 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
121 be 1 or 2 depending on whether we're starting without or with a
123 startup_inferior (START_INFERIOR_TRAPS_EXPECTED
);
125 /* On some targets, there must be some explicit actions taken after
126 the inferior has been started up. */
127 target_post_startup_inferior (pid_to_ptid (pid
));
130 /* Start a new inferior Unix child process. EXEC_FILE is the file to
131 run, ALLARGS is a string containing the arguments to the program.
132 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
136 inf_ptrace_create_inferior (char *exec_file
, char *allargs
, char **env
,
139 fork_inferior (exec_file
, allargs
, env
, inf_ptrace_me
, inf_ptrace_him
,
143 #ifdef PT_GET_PROCESS_STATE
146 inf_ptrace_post_startup_inferior (ptid_t pid
)
150 /* Set the initial event mask. */
151 memset (&pe
, 0, sizeof pe
);
152 pe
.pe_set_event
|= PTRACE_FORK
;
153 if (ptrace (PT_SET_EVENT_MASK
, ptid_get_pid (pid
),
154 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
155 perror_with_name (("ptrace"));
160 /* Clean up a rotting corpse of an inferior after it died. */
163 inf_ptrace_mourn_inferior (void)
167 /* Wait just one more time to collect the inferior's exit status.
168 Do not check whether this succeeds though, since we may be
169 dealing with a process that we attached to. Such a process will
170 only report its exit status to its original parent. */
171 waitpid (ptid_get_pid (inferior_ptid
), &status
, 0);
173 unpush_target (ptrace_ops_hack
);
174 generic_mourn_inferior ();
177 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
178 be chatty about it. */
181 inf_ptrace_attach (char *args
, int from_tty
)
188 error_no_arg (_("process-id to attach"));
191 pid
= strtol (args
, &dummy
, 0);
192 /* Some targets don't set errno on errors, grrr! */
193 if (pid
== 0 && args
== dummy
)
194 error (_("Illegal process-id: %s."), args
);
196 if (pid
== getpid ()) /* Trying to masturbate? */
197 error (_("I refuse to debug myself!"));
201 exec_file
= get_exec_file (0);
204 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file
,
205 target_pid_to_str (pid_to_ptid (pid
)));
207 printf_unfiltered (_("Attaching to %s\n"),
208 target_pid_to_str (pid_to_ptid (pid
)));
210 gdb_flush (gdb_stdout
);
215 ptrace (PT_ATTACH
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
217 perror_with_name (("ptrace"));
220 error (_("This system does not support attaching to a process"));
223 inferior_ptid
= pid_to_ptid (pid
);
224 push_target (ptrace_ops_hack
);
226 /* Do this first, before anything has had a chance to query the
227 inferior's symbol table or similar. */
228 observer_notify_inferior_created (¤t_target
, from_tty
);
231 #ifdef PT_GET_PROCESS_STATE
234 inf_ptrace_post_attach (int pid
)
238 /* Set the initial event mask. */
239 memset (&pe
, 0, sizeof pe
);
240 pe
.pe_set_event
|= PTRACE_FORK
;
241 if (ptrace (PT_SET_EVENT_MASK
, pid
,
242 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
243 perror_with_name (("ptrace"));
248 /* Detach from the inferior, optionally passing it the signal
249 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
252 inf_ptrace_detach (char *args
, int from_tty
)
254 pid_t pid
= ptid_get_pid (inferior_ptid
);
259 char *exec_file
= get_exec_file (0);
262 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file
,
263 target_pid_to_str (pid_to_ptid (pid
)));
264 gdb_flush (gdb_stdout
);
270 /* We'd better not have left any breakpoints in the program or it'll
271 die when it hits one. Also note that this may only work if we
272 previously attached to the inferior. It *might* work if we
273 started the process ourselves. */
275 ptrace (PT_DETACH
, pid
, (PTRACE_TYPE_ARG3
)1, sig
);
277 perror_with_name (("ptrace"));
280 error (_("This system does not support detaching from a process"));
283 inferior_ptid
= null_ptid
;
284 unpush_target (ptrace_ops_hack
);
287 /* Kill the inferior. */
290 inf_ptrace_kill (void)
292 pid_t pid
= ptid_get_pid (inferior_ptid
);
298 ptrace (PT_KILL
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
299 waitpid (pid
, &status
, 0);
301 target_mourn_inferior ();
304 /* Stop the inferior. */
307 inf_ptrace_stop (void)
309 /* Send a SIGINT to the process group. This acts just like the user
310 typed a ^C on the controlling terminal. Note that using a
311 negative process number in kill() is a System V-ism. The proper
312 BSD interface is killpg(). However, all modern BSDs support the
313 System V interface too. */
314 kill (-inferior_process_group
, SIGINT
);
317 /* Resume execution of thread PTID, or all threads if PTID is -1. If
318 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
322 inf_ptrace_resume (ptid_t ptid
, int step
, enum target_signal signal
)
324 pid_t pid
= ptid_get_pid (ptid
);
325 int request
= PT_CONTINUE
;
328 /* Resume all threads. Traditionally ptrace() only supports
329 single-threaded processes, so simply resume the inferior. */
330 pid
= ptid_get_pid (inferior_ptid
);
334 /* If this system does not support PT_STEP, a higher level
335 function will have called single_step() to transmute the step
336 request into a continue request (by setting breakpoints on
337 all possible successor instructions), so we don't have to
338 worry about that here. */
342 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
343 where it was. If GDB wanted it to start some other way, we have
344 already written a new program counter value to the child. */
346 ptrace (request
, pid
, (PTRACE_TYPE_ARG3
)1, target_signal_to_host (signal
));
348 perror_with_name (("ptrace"));
351 /* Wait for the child specified by PTID to do something. Return the
352 process ID of the child, or MINUS_ONE_PTID in case of error; store
353 the status in *OURSTATUS. */
356 inf_ptrace_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
359 int status
, save_errno
;
368 pid
= waitpid (ptid_get_pid (ptid
), &status
, 0);
371 while (pid
== -1 && errno
== EINTR
);
374 clear_sigint_trap ();
378 fprintf_unfiltered (gdb_stderr
,
379 _("Child process unexpectedly missing: %s.\n"),
380 safe_strerror (save_errno
));
382 /* Claim it exited with unknown signal. */
383 ourstatus
->kind
= TARGET_WAITKIND_SIGNALLED
;
384 ourstatus
->value
.sig
= TARGET_SIGNAL_UNKNOWN
;
385 return minus_one_ptid
;
388 /* Ignore terminated detached child processes. */
389 if (!WIFSTOPPED (status
) && pid
!= ptid_get_pid (inferior_ptid
))
394 #ifdef PT_GET_PROCESS_STATE
395 if (WIFSTOPPED (status
))
400 if (ptrace (PT_GET_PROCESS_STATE
, pid
,
401 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
402 perror_with_name (("ptrace"));
404 switch (pe
.pe_report_event
)
407 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
408 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
410 /* Make sure the other end of the fork is stopped too. */
411 fpid
= waitpid (pe
.pe_other_pid
, &status
, 0);
413 perror_with_name (("waitpid"));
415 if (ptrace (PT_GET_PROCESS_STATE
, fpid
,
416 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
417 perror_with_name (("ptrace"));
419 gdb_assert (pe
.pe_report_event
== PTRACE_FORK
);
420 gdb_assert (pe
.pe_other_pid
== pid
);
421 if (fpid
== ptid_get_pid (inferior_ptid
))
423 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
424 return pid_to_ptid (fpid
);
427 return pid_to_ptid (pid
);
432 store_waitstatus (ourstatus
, status
);
433 return pid_to_ptid (pid
);
436 /* Attempt a transfer all LEN bytes starting at OFFSET between the
437 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
438 Return the number of bytes actually transferred. */
441 inf_ptrace_xfer_partial (struct target_ops
*ops
, enum target_object object
,
442 const char *annex
, gdb_byte
*readbuf
,
443 const gdb_byte
*writebuf
,
444 ULONGEST offset
, LONGEST len
)
446 pid_t pid
= ptid_get_pid (inferior_ptid
);
450 case TARGET_OBJECT_MEMORY
:
452 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
453 request that promises to be much more efficient in reading
454 and writing data in the traced process's address space. */
456 struct ptrace_io_desc piod
;
458 /* NOTE: We assume that there are no distinct address spaces
459 for instruction and data. However, on OpenBSD 3.9 and
460 later, PIOD_WRITE_D doesn't allow changing memory that's
461 mapped read-only. Since most code segments will be
462 read-only, using PIOD_WRITE_D will prevent us from
463 inserting breakpoints, so we use PIOD_WRITE_I instead. */
464 piod
.piod_op
= writebuf
? PIOD_WRITE_I
: PIOD_READ_D
;
465 piod
.piod_addr
= writebuf
? (void *) writebuf
: readbuf
;
466 piod
.piod_offs
= (void *) (long) offset
;
470 if (ptrace (PT_IO
, pid
, (caddr_t
)&piod
, 0) == 0)
471 /* Return the actual number of bytes read or written. */
472 return piod
.piod_len
;
473 /* If the PT_IO request is somehow not supported, fallback on
474 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
475 to indicate failure. */
483 PTRACE_TYPE_RET word
;
484 gdb_byte byte
[sizeof (PTRACE_TYPE_RET
)];
486 ULONGEST rounded_offset
;
489 /* Round the start offset down to the next long word
491 rounded_offset
= offset
& -(ULONGEST
) sizeof (PTRACE_TYPE_RET
);
493 /* Since ptrace will transfer a single word starting at that
494 rounded_offset the partial_len needs to be adjusted down to
495 that (remember this function only does a single transfer).
496 Should the required length be even less, adjust it down
498 partial_len
= (rounded_offset
+ sizeof (PTRACE_TYPE_RET
)) - offset
;
499 if (partial_len
> len
)
504 /* If OFFSET:PARTIAL_LEN is smaller than
505 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
506 be needed. Read in the entire word. */
507 if (rounded_offset
< offset
508 || (offset
+ partial_len
509 < rounded_offset
+ sizeof (PTRACE_TYPE_RET
)))
510 /* Need part of initial word -- fetch it. */
511 buffer
.word
= ptrace (PT_READ_I
, pid
,
512 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, 0);
514 /* Copy data to be written over corresponding part of
516 memcpy (buffer
.byte
+ (offset
- rounded_offset
),
517 writebuf
, partial_len
);
520 ptrace (PT_WRITE_D
, pid
,
521 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, buffer
.word
);
524 /* Using the appropriate one (I or D) is necessary for
525 Gould NP1, at least. */
527 ptrace (PT_WRITE_I
, pid
,
528 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, buffer
.word
);
537 buffer
.word
= ptrace (PT_READ_I
, pid
,
538 (PTRACE_TYPE_ARG3
)(long)rounded_offset
, 0);
541 /* Copy appropriate bytes out of the buffer. */
542 memcpy (readbuf
, buffer
.byte
+ (offset
- rounded_offset
),
549 case TARGET_OBJECT_UNWIND_TABLE
:
552 case TARGET_OBJECT_AUXV
:
555 case TARGET_OBJECT_WCOOKIE
:
563 /* Return non-zero if the thread specified by PTID is alive. */
566 inf_ptrace_thread_alive (ptid_t ptid
)
568 /* ??? Is kill the right way to do this? */
569 return (kill (ptid_get_pid (ptid
), 0) != -1);
572 /* Print status information about what we're accessing. */
575 inf_ptrace_files_info (struct target_ops
*ignore
)
577 printf_filtered (_("\tUsing the running image of %s %s.\n"),
578 attach_flag
? "attached" : "child",
579 target_pid_to_str (inferior_ptid
));
582 /* Create a prototype ptrace target. The client can override it with
586 inf_ptrace_target (void)
588 struct target_ops
*t
= inf_child_target ();
590 t
->to_attach
= inf_ptrace_attach
;
591 t
->to_detach
= inf_ptrace_detach
;
592 t
->to_resume
= inf_ptrace_resume
;
593 t
->to_wait
= inf_ptrace_wait
;
594 t
->to_files_info
= inf_ptrace_files_info
;
595 t
->to_kill
= inf_ptrace_kill
;
596 t
->to_create_inferior
= inf_ptrace_create_inferior
;
597 #ifdef PT_GET_PROCESS_STATE
598 t
->to_follow_fork
= inf_ptrace_follow_fork
;
599 t
->to_post_startup_inferior
= inf_ptrace_post_startup_inferior
;
600 t
->to_post_attach
= inf_ptrace_post_attach
;
602 t
->to_mourn_inferior
= inf_ptrace_mourn_inferior
;
603 t
->to_thread_alive
= inf_ptrace_thread_alive
;
604 t
->to_pid_to_str
= normal_pid_to_str
;
605 t
->to_stop
= inf_ptrace_stop
;
606 t
->to_xfer_partial
= inf_ptrace_xfer_partial
;
613 /* Pointer to a function that returns the offset within the user area
614 where a particular register is stored. */
615 static CORE_ADDR (*inf_ptrace_register_u_offset
)(int);
617 /* Fetch register REGNUM from the inferior. */
620 inf_ptrace_fetch_register (int regnum
)
624 PTRACE_TYPE_RET
*buf
;
627 if (CANNOT_FETCH_REGISTER (regnum
))
629 regcache_raw_supply (current_regcache
, regnum
, NULL
);
633 /* Cater for systems like GNU/Linux, that implement threads as
634 separate processes. */
635 pid
= ptid_get_lwp (inferior_ptid
);
637 pid
= ptid_get_pid (inferior_ptid
);
639 /* This isn't really an address, but ptrace thinks of it as one. */
640 addr
= inf_ptrace_register_u_offset (regnum
);
641 size
= register_size (current_gdbarch
, regnum
);
643 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
646 /* Read the register contents from the inferior a chunk at a time. */
647 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
650 buf
[i
] = ptrace (PT_READ_U
, pid
, (PTRACE_TYPE_ARG3
)addr
, 0);
652 error (_("Couldn't read register %s (#%d): %s."),
653 REGISTER_NAME (regnum
), regnum
, safe_strerror (errno
));
655 addr
+= sizeof (PTRACE_TYPE_RET
);
657 regcache_raw_supply (current_regcache
, regnum
, buf
);
660 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
661 for all registers. */
664 inf_ptrace_fetch_registers (int regnum
)
667 for (regnum
= 0; regnum
< NUM_REGS
; regnum
++)
668 inf_ptrace_fetch_register (regnum
);
670 inf_ptrace_fetch_register (regnum
);
673 /* Store register REGNUM into the inferior. */
676 inf_ptrace_store_register (int regnum
)
680 PTRACE_TYPE_RET
*buf
;
683 if (CANNOT_STORE_REGISTER (regnum
))
686 /* Cater for systems like GNU/Linux, that implement threads as
687 separate processes. */
688 pid
= ptid_get_lwp (inferior_ptid
);
690 pid
= ptid_get_pid (inferior_ptid
);
692 /* This isn't really an address, but ptrace thinks of it as one. */
693 addr
= inf_ptrace_register_u_offset (regnum
);
694 size
= register_size (current_gdbarch
, regnum
);
696 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
699 /* Write the register contents into the inferior a chunk at a time. */
700 regcache_raw_collect (current_regcache
, regnum
, buf
);
701 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
704 ptrace (PT_WRITE_U
, pid
, (PTRACE_TYPE_ARG3
)addr
, buf
[i
]);
706 error (_("Couldn't write register %s (#%d): %s."),
707 REGISTER_NAME (regnum
), regnum
, safe_strerror (errno
));
709 addr
+= sizeof (PTRACE_TYPE_RET
);
713 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
714 this for all registers. */
717 inf_ptrace_store_registers (int regnum
)
720 for (regnum
= 0; regnum
< NUM_REGS
; regnum
++)
721 inf_ptrace_store_register (regnum
);
723 inf_ptrace_store_register (regnum
);
726 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
727 a function returning the offset within the user area where a
728 particular register is stored. */
731 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset
)(int))
733 struct target_ops
*t
= inf_ptrace_target();
735 gdb_assert (register_u_offset
);
736 inf_ptrace_register_u_offset
= register_u_offset
;
737 t
->to_fetch_registers
= inf_ptrace_fetch_registers
;
738 t
->to_store_registers
= inf_ptrace_store_registers
;