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
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_stdint.h"
30 #include "gdb_assert.h"
31 #include "gdb_string.h"
32 #include "gdb_ptrace.h"
36 #include "inf-child.h"
38 /* HACK: Save the ptrace ops returned by inf_ptrace_target. */
39 static struct target_ops
*ptrace_ops_hack
;
42 #ifdef PT_GET_PROCESS_STATE
45 inf_ptrace_follow_fork (struct target_ops
*ops
, int follow_child
)
50 /* FIXME: kettenis/20050720: This stuff should really be passed as
51 an argument by our caller. */
54 struct target_waitstatus status
;
56 get_last_target_status (&ptid
, &status
);
57 gdb_assert (status
.kind
== TARGET_WAITKIND_FORKED
);
59 pid
= ptid_get_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 inferior_ptid
= pid_to_ptid (fpid
);
72 detach_breakpoints (pid
);
74 /* Reset breakpoints in the child as appropriate. */
75 follow_inferior_reset_breakpoints ();
77 if (ptrace (PT_DETACH
, pid
, (PTRACE_TYPE_ARG3
)1, 0) == -1)
78 perror_with_name (("ptrace"));
82 inferior_ptid
= pid_to_ptid (pid
);
83 detach_breakpoints (fpid
);
85 if (ptrace (PT_DETACH
, fpid
, (PTRACE_TYPE_ARG3
)1, 0) == -1)
86 perror_with_name (("ptrace"));
92 #endif /* PT_GET_PROCESS_STATE */
95 /* Prepare to be traced. */
100 /* "Trace me, Dr. Memory!" */
101 ptrace (PT_TRACE_ME
, 0, (PTRACE_TYPE_ARG3
)0, 0);
104 /* Start tracing PID. */
107 inf_ptrace_him (int pid
)
109 push_target (ptrace_ops_hack
);
111 /* On some targets, there must be some explicit synchronization
112 between the parent and child processes after the debugger
113 forks, and before the child execs the debuggee program. This
114 call basically gives permission for the child to exec. */
116 target_acknowledge_created_inferior (pid
);
118 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
119 be 1 or 2 depending on whether we're starting without or with a
121 startup_inferior (START_INFERIOR_TRAPS_EXPECTED
);
123 /* On some targets, there must be some explicit actions taken after
124 the inferior has been started up. */
125 target_post_startup_inferior (pid_to_ptid (pid
));
128 /* Start a new inferior Unix child process. EXEC_FILE is the file to
129 run, ALLARGS is a string containing the arguments to the program.
130 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
134 inf_ptrace_create_inferior (char *exec_file
, char *allargs
, char **env
,
137 fork_inferior (exec_file
, allargs
, env
, inf_ptrace_me
, inf_ptrace_him
,
141 #ifdef PT_GET_PROCESS_STATE
144 inf_ptrace_post_startup_inferior (ptid_t pid
)
148 /* Set the initial event mask. */
149 memset (&pe
, 0, sizeof pe
);
150 pe
.pe_set_event
|= PTRACE_FORK
;
151 if (ptrace (PT_SET_EVENT_MASK
, ptid_get_pid (pid
),
152 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
153 perror_with_name (("ptrace"));
158 /* Clean up a rotting corpse of an inferior after it died. */
161 inf_ptrace_mourn_inferior (void)
165 /* Wait just one more time to collect the inferior's exit status.
166 Do not check whether this succeeds though, since we may be
167 dealing with a process that we attached to. Such a process will
168 only report its exit status to its original parent. */
169 waitpid (ptid_get_pid (inferior_ptid
), &status
, 0);
171 unpush_target (ptrace_ops_hack
);
172 generic_mourn_inferior ();
175 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
176 be chatty about it. */
179 inf_ptrace_attach (char *args
, int from_tty
)
186 error_no_arg (_("process-id to attach"));
189 pid
= strtol (args
, &dummy
, 0);
190 /* Some targets don't set errno on errors, grrr! */
191 if (pid
== 0 && args
== dummy
)
192 error (_("Illegal process-id: %s."), args
);
194 if (pid
== getpid ()) /* Trying to masturbate? */
195 error (_("I refuse to debug myself!"));
199 exec_file
= get_exec_file (0);
202 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file
,
203 target_pid_to_str (pid_to_ptid (pid
)));
205 printf_unfiltered (_("Attaching to %s\n"),
206 target_pid_to_str (pid_to_ptid (pid
)));
208 gdb_flush (gdb_stdout
);
213 ptrace (PT_ATTACH
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
215 perror_with_name (("ptrace"));
218 error (_("This system does not support attaching to a process"));
221 inferior_ptid
= pid_to_ptid (pid
);
222 push_target (ptrace_ops_hack
);
225 #ifdef PT_GET_PROCESS_STATE
228 inf_ptrace_post_attach (int pid
)
232 /* Set the initial event mask. */
233 memset (&pe
, 0, sizeof pe
);
234 pe
.pe_set_event
|= PTRACE_FORK
;
235 if (ptrace (PT_SET_EVENT_MASK
, pid
,
236 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
237 perror_with_name (("ptrace"));
242 /* Detach from the inferior, optionally passing it the signal
243 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
246 inf_ptrace_detach (char *args
, int from_tty
)
248 pid_t pid
= ptid_get_pid (inferior_ptid
);
253 char *exec_file
= get_exec_file (0);
256 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file
,
257 target_pid_to_str (pid_to_ptid (pid
)));
258 gdb_flush (gdb_stdout
);
264 /* We'd better not have left any breakpoints in the program or it'll
265 die when it hits one. Also note that this may only work if we
266 previously attached to the inferior. It *might* work if we
267 started the process ourselves. */
269 ptrace (PT_DETACH
, pid
, (PTRACE_TYPE_ARG3
)1, sig
);
271 perror_with_name (("ptrace"));
274 error (_("This system does not support detaching from a process"));
277 inferior_ptid
= null_ptid
;
278 unpush_target (ptrace_ops_hack
);
281 /* Kill the inferior. */
284 inf_ptrace_kill (void)
286 pid_t pid
= ptid_get_pid (inferior_ptid
);
292 ptrace (PT_KILL
, pid
, (PTRACE_TYPE_ARG3
)0, 0);
293 waitpid (pid
, &status
, 0);
295 target_mourn_inferior ();
298 /* Stop the inferior. */
301 inf_ptrace_stop (void)
303 /* Send a SIGINT to the process group. This acts just like the user
304 typed a ^C on the controlling terminal. Note that using a
305 negative process number in kill() is a System V-ism. The proper
306 BSD interface is killpg(). However, all modern BSDs support the
307 System V interface too. */
308 kill (-inferior_process_group
, SIGINT
);
311 /* Resume execution of thread PTID, or all threads if PTID is -1. If
312 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
316 inf_ptrace_resume (ptid_t ptid
, int step
, enum target_signal signal
)
318 pid_t pid
= ptid_get_pid (ptid
);
319 int request
= PT_CONTINUE
;
322 /* Resume all threads. Traditionally ptrace() only supports
323 single-threaded processes, so simply resume the inferior. */
324 pid
= ptid_get_pid (inferior_ptid
);
328 /* If this system does not support PT_STEP, a higher level
329 function will have called single_step() to transmute the step
330 request into a continue request (by setting breakpoints on
331 all possible successor instructions), so we don't have to
332 worry about that here. */
336 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
337 where it was. If GDB wanted it to start some other way, we have
338 already written a new program counter value to the child. */
340 ptrace (request
, pid
, (PTRACE_TYPE_ARG3
)1, target_signal_to_host (signal
));
342 perror_with_name (("ptrace"));
345 /* Wait for the child specified by PTID to do something. Return the
346 process ID of the child, or MINUS_ONE_PTID in case of error; store
347 the status in *OURSTATUS. */
350 inf_ptrace_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
353 int status
, save_errno
;
362 pid
= waitpid (ptid_get_pid (ptid
), &status
, 0);
365 while (pid
== -1 && errno
== EINTR
);
368 clear_sigint_trap ();
372 fprintf_unfiltered (gdb_stderr
,
373 _("Child process unexpectedly missing: %s.\n"),
374 safe_strerror (save_errno
));
376 /* Claim it exited with unknown signal. */
377 ourstatus
->kind
= TARGET_WAITKIND_SIGNALLED
;
378 ourstatus
->value
.sig
= TARGET_SIGNAL_UNKNOWN
;
379 return minus_one_ptid
;
382 /* Ignore terminated detached child processes. */
383 if (!WIFSTOPPED (status
) && pid
!= ptid_get_pid (inferior_ptid
))
388 #ifdef PT_GET_PROCESS_STATE
389 if (WIFSTOPPED (status
))
394 if (ptrace (PT_GET_PROCESS_STATE
, pid
,
395 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
396 perror_with_name (("ptrace"));
398 switch (pe
.pe_report_event
)
401 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
402 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
404 /* Make sure the other end of the fork is stopped too. */
405 fpid
= waitpid (pe
.pe_other_pid
, &status
, 0);
407 perror_with_name (("waitpid"));
409 if (ptrace (PT_GET_PROCESS_STATE
, fpid
,
410 (PTRACE_TYPE_ARG3
)&pe
, sizeof pe
) == -1)
411 perror_with_name (("ptrace"));
413 gdb_assert (pe
.pe_report_event
== PTRACE_FORK
);
414 gdb_assert (pe
.pe_other_pid
== pid
);
415 if (fpid
== ptid_get_pid (inferior_ptid
))
417 ourstatus
->value
.related_pid
= pe
.pe_other_pid
;
418 return pid_to_ptid (fpid
);
421 return pid_to_ptid (pid
);
426 store_waitstatus (ourstatus
, status
);
427 return pid_to_ptid (pid
);
430 /* Attempt a transfer all LEN bytes starting at OFFSET between the
431 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
432 Return the number of bytes actually transferred. */
435 inf_ptrace_xfer_partial (struct target_ops
*ops
, enum target_object object
,
436 const char *annex
, gdb_byte
*readbuf
,
437 const gdb_byte
*writebuf
,
438 ULONGEST offset
, LONGEST len
)
440 pid_t pid
= ptid_get_pid (inferior_ptid
);
444 case TARGET_OBJECT_MEMORY
:
446 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
447 request that promises to be much more efficient in reading
448 and writing data in the traced process's address space. */
450 struct ptrace_io_desc piod
;
452 /* NOTE: We assume that there are no distinct address spaces
453 for instruction and data. However, on OpenBSD 3.9 and
454 later, PIOD_WRITE_D doesn't allow changing memory that's
455 mapped read-only. Since most code segments will be
456 read-only, using PIOD_WRITE_D will prevent us from
457 inserting breakpoints, so we use PIOD_WRITE_I instead. */
458 piod
.piod_op
= writebuf
? PIOD_WRITE_I
: 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
)(uintptr_t)
509 /* Copy data to be written over corresponding part of
511 memcpy (buffer
.byte
+ (offset
- rounded_offset
),
512 writebuf
, partial_len
);
515 ptrace (PT_WRITE_D
, pid
,
516 (PTRACE_TYPE_ARG3
)(uintptr_t)rounded_offset
,
520 /* Using the appropriate one (I or D) is necessary for
521 Gould NP1, at least. */
523 ptrace (PT_WRITE_I
, pid
,
524 (PTRACE_TYPE_ARG3
)(uintptr_t)rounded_offset
,
534 buffer
.word
= ptrace (PT_READ_I
, pid
,
535 (PTRACE_TYPE_ARG3
)(uintptr_t)rounded_offset
,
539 /* Copy appropriate bytes out of the buffer. */
540 memcpy (readbuf
, buffer
.byte
+ (offset
- rounded_offset
),
547 case TARGET_OBJECT_UNWIND_TABLE
:
550 case TARGET_OBJECT_AUXV
:
553 case TARGET_OBJECT_WCOOKIE
:
561 /* Return non-zero if the thread specified by PTID is alive. */
564 inf_ptrace_thread_alive (ptid_t ptid
)
566 /* ??? Is kill the right way to do this? */
567 return (kill (ptid_get_pid (ptid
), 0) != -1);
570 /* Print status information about what we're accessing. */
573 inf_ptrace_files_info (struct target_ops
*ignore
)
575 printf_filtered (_("\tUsing the running image of %s %s.\n"),
576 attach_flag
? "attached" : "child",
577 target_pid_to_str (inferior_ptid
));
580 /* Create a prototype ptrace target. The client can override it with
584 inf_ptrace_target (void)
586 struct target_ops
*t
= inf_child_target ();
588 t
->to_attach
= inf_ptrace_attach
;
589 t
->to_detach
= inf_ptrace_detach
;
590 t
->to_resume
= inf_ptrace_resume
;
591 t
->to_wait
= inf_ptrace_wait
;
592 t
->to_files_info
= inf_ptrace_files_info
;
593 t
->to_kill
= inf_ptrace_kill
;
594 t
->to_create_inferior
= inf_ptrace_create_inferior
;
595 #ifdef PT_GET_PROCESS_STATE
596 t
->to_follow_fork
= inf_ptrace_follow_fork
;
597 t
->to_post_startup_inferior
= inf_ptrace_post_startup_inferior
;
598 t
->to_post_attach
= inf_ptrace_post_attach
;
600 t
->to_mourn_inferior
= inf_ptrace_mourn_inferior
;
601 t
->to_thread_alive
= inf_ptrace_thread_alive
;
602 t
->to_pid_to_str
= normal_pid_to_str
;
603 t
->to_stop
= inf_ptrace_stop
;
604 t
->to_xfer_partial
= inf_ptrace_xfer_partial
;
611 /* Pointer to a function that returns the offset within the user area
612 where a particular register is stored. */
613 static CORE_ADDR (*inf_ptrace_register_u_offset
)(struct gdbarch
*, int, int);
615 /* Fetch register REGNUM from the inferior. */
618 inf_ptrace_fetch_register (struct regcache
*regcache
, int regnum
)
620 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
623 PTRACE_TYPE_RET
*buf
;
626 /* This isn't really an address, but ptrace thinks of it as one. */
627 addr
= inf_ptrace_register_u_offset (gdbarch
, regnum
, 0);
628 if (addr
== (CORE_ADDR
)-1
629 || gdbarch_cannot_fetch_register (gdbarch
, regnum
))
631 regcache_raw_supply (regcache
, regnum
, NULL
);
635 /* Cater for systems like GNU/Linux, that implement threads as
636 separate processes. */
637 pid
= ptid_get_lwp (inferior_ptid
);
639 pid
= ptid_get_pid (inferior_ptid
);
641 size
= register_size (gdbarch
, regnum
);
642 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
645 /* Read the register contents from the inferior a chunk at a time. */
646 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
649 buf
[i
] = ptrace (PT_READ_U
, pid
, (PTRACE_TYPE_ARG3
)(uintptr_t)addr
, 0);
651 error (_("Couldn't read register %s (#%d): %s."),
652 gdbarch_register_name (gdbarch
, regnum
),
653 regnum
, safe_strerror (errno
));
655 addr
+= sizeof (PTRACE_TYPE_RET
);
657 regcache_raw_supply (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 (struct regcache
*regcache
, int regnum
)
668 regnum
< gdbarch_num_regs (get_regcache_arch (regcache
));
670 inf_ptrace_fetch_register (regcache
, regnum
);
672 inf_ptrace_fetch_register (regcache
, regnum
);
675 /* Store register REGNUM into the inferior. */
678 inf_ptrace_store_register (const struct regcache
*regcache
, int regnum
)
680 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
683 PTRACE_TYPE_RET
*buf
;
686 /* This isn't really an address, but ptrace thinks of it as one. */
687 addr
= inf_ptrace_register_u_offset (gdbarch
, regnum
, 1);
688 if (addr
== (CORE_ADDR
)-1
689 || gdbarch_cannot_store_register (gdbarch
, regnum
))
692 /* Cater for systems like GNU/Linux, that implement threads as
693 separate processes. */
694 pid
= ptid_get_lwp (inferior_ptid
);
696 pid
= ptid_get_pid (inferior_ptid
);
698 size
= register_size (gdbarch
, regnum
);
699 gdb_assert ((size
% sizeof (PTRACE_TYPE_RET
)) == 0);
702 /* Write the register contents into the inferior a chunk at a time. */
703 regcache_raw_collect (regcache
, regnum
, buf
);
704 for (i
= 0; i
< size
/ sizeof (PTRACE_TYPE_RET
); i
++)
707 ptrace (PT_WRITE_U
, pid
, (PTRACE_TYPE_ARG3
)(uintptr_t)addr
, buf
[i
]);
709 error (_("Couldn't write register %s (#%d): %s."),
710 gdbarch_register_name (gdbarch
, regnum
),
711 regnum
, safe_strerror (errno
));
713 addr
+= sizeof (PTRACE_TYPE_RET
);
717 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
718 this for all registers. */
721 inf_ptrace_store_registers (struct regcache
*regcache
, int regnum
)
725 regnum
< gdbarch_num_regs (get_regcache_arch (regcache
));
727 inf_ptrace_store_register (regcache
, regnum
);
729 inf_ptrace_store_register (regcache
, regnum
);
732 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
733 a function returning the offset within the user area where a
734 particular register is stored. */
737 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset
)
738 (struct gdbarch
*, int, int))
740 struct target_ops
*t
= inf_ptrace_target();
742 gdb_assert (register_u_offset
);
743 inf_ptrace_register_u_offset
= register_u_offset
;
744 t
->to_fetch_registers
= inf_ptrace_fetch_registers
;
745 t
->to_store_registers
= inf_ptrace_store_registers
;