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 /* Stub function which causes the inferior that runs it, to be ptrace-able
45 by its parent process. */
50 /* "Trace me, Dr. Memory!" */
51 ptrace (0, 0, (PTRACE_TYPE_ARG3) 0, 0);
54 /* Stub function which causes the GDB that runs it, to start ptrace-ing
58 inf_ptrace_him (int pid)
60 push_target (ptrace_ops_hack);
62 /* On some targets, there must be some explicit synchronization
63 between the parent and child processes after the debugger
64 forks, and before the child execs the debuggee program. This
65 call basically gives permission for the child to exec. */
67 target_acknowledge_created_inferior (pid);
69 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
70 be 1 or 2 depending on whether we're starting without or with a
72 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
74 /* On some targets, there must be some explicit actions taken after
75 the inferior has been started up. */
76 target_post_startup_inferior (pid_to_ptid (pid));
79 /* Start an inferior Unix child process and sets inferior_ptid to its
80 pid. EXEC_FILE is the file to run. ALLARGS is a string containing
81 the arguments to the program. ENV is the environment vector to
82 pass. Errors reported with error(). */
85 inf_ptrace_create_inferior (char *exec_file, char *allargs, char **env,
88 fork_inferior (exec_file, allargs, env, inf_ptrace_me, inf_ptrace_him,
90 /* We are at the first instruction we care about. */
91 observer_notify_inferior_created (¤t_target, from_tty);
92 /* Pedal to the metal... */
93 proceed ((CORE_ADDR) -1, TARGET_SIGNAL_0, 0);
97 inf_ptrace_mourn_inferior (void)
99 unpush_target (ptrace_ops_hack);
100 generic_mourn_inferior ();
103 /* Attach to process PID, then initialize for debugging it. */
106 inf_ptrace_attach (char *args, int from_tty)
113 error_no_arg (_("process-id to attach"));
116 pid = strtol (args, &dummy, 0);
117 /* Some targets don't set errno on errors, grrr! */
118 if (pid == 0 && args == dummy)
119 error (_("Illegal process-id: %s."), args);
121 if (pid == getpid ()) /* Trying to masturbate? */
122 error (_("I refuse to debug myself!"));
126 exec_file = (char *) get_exec_file (0);
129 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
130 target_pid_to_str (pid_to_ptid (pid)));
132 printf_unfiltered (_("Attaching to %s\n"),
133 target_pid_to_str (pid_to_ptid (pid)));
135 gdb_flush (gdb_stdout);
140 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3) 0, 0);
142 perror_with_name (("ptrace"));
145 error (_("This system does not support attaching to a process"));
148 inferior_ptid = pid_to_ptid (pid);
149 push_target (ptrace_ops_hack);
151 /* Do this first, before anything has had a chance to query the
152 inferior's symbol table or similar. */
153 observer_notify_inferior_created (¤t_target, from_tty);
156 /* Take a program previously attached to and detaches it. The program
157 resumes execution and will no longer stop on signals, etc. We'd
158 better not have left any breakpoints in the program or it'll die
159 when it hits one. For this to work, it may be necessary for the
160 process to have been previously attached. It *might* work if the
161 program was started via the normal ptrace (PTRACE_TRACEME). */
164 inf_ptrace_detach (char *args, int from_tty)
167 int pid = PIDGET (inferior_ptid);
171 char *exec_file = get_exec_file (0);
174 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
175 target_pid_to_str (pid_to_ptid (pid)));
176 gdb_flush (gdb_stdout);
183 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3) 1, sig);
185 perror_with_name (("ptrace"));
188 error (_("This system does not support detaching from a process"));
191 inferior_ptid = null_ptid;
192 unpush_target (ptrace_ops_hack);
196 inf_ptrace_kill_inferior (void)
199 int pid = PIDGET (inferior_ptid);
204 /* This once used to call "kill" to kill the inferior just in case
205 the inferior was still running. As others have noted in the past
206 (kingdon) there shouldn't be any way to get here if the inferior
207 is still running -- else there's a major problem elsewere in GDB
208 and it needs to be fixed.
210 The kill call causes problems under HP-UX 10, so it's been
211 removed; if this causes problems we'll deal with them as they
213 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3) 0, 0);
215 target_mourn_inferior ();
218 /* Send a SIGINT to the process group. This acts just like the user
219 typed a ^C on the controlling terminal.
221 FIXME: This may not be correct for all systems. Some may want to
222 use killpg() instead of kill (-pgrp). */
225 inf_ptrace_stop (void)
227 kill (-inferior_process_group, SIGINT);
230 /* Resume execution of the inferior process. If STEP is nonzero,
231 single-step it. If SIGNAL is nonzero, give it that signal. */
234 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
236 int request = PT_CONTINUE;
237 int pid = PIDGET (ptid);
240 /* Resume all threads. */
241 /* I think this only gets used in the non-threaded case, where
242 "resume all threads" and "resume inferior_ptid" are the
244 pid = PIDGET (inferior_ptid);
248 /* If this system does not support PT_STEP, a higher level
249 function will have called single_step() to transmute the step
250 request into a continue request (by setting breakpoints on
251 all possible successor instructions), so we don't have to
252 worry about that here. */
256 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
257 where it was. If GDB wanted it to start some other way, we have
258 already written a new PC value to the child. */
260 ptrace (request, pid, (PTRACE_TYPE_ARG3) 1, target_signal_to_host (signal));
262 perror_with_name (("ptrace"));
265 /* Wait for child to do something. Return pid of child, or -1 in case
266 of error; store status through argument pointer OURSTATUS. */
269 inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
273 char *execd_pathname = NULL;
277 enum target_waitkind kind;
282 set_sigint_trap (); /* Causes SIGINT to be passed on to the
286 pid = wait (&status);
292 clear_sigint_trap ();
296 if (save_errno == EINTR)
299 fprintf_unfiltered (gdb_stderr,
300 "Child process unexpectedly missing: %s.\n",
301 safe_strerror (save_errno));
303 /* Claim it exited with unknown signal. */
304 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
305 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
306 return pid_to_ptid (-1);
310 if (target_has_exited (pid, status, &exit_status))
312 /* ??rehrauer: For now, ignore this. */
316 if (!target_thread_alive (pid_to_ptid (pid)))
318 ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
319 return pid_to_ptid (pid);
322 while (pid != PIDGET (inferior_ptid)); /* Some other child died or
325 store_waitstatus (ourstatus, status);
326 return pid_to_ptid (pid);
330 inf_ptrace_has_exited (int pid, int wait_status, int *exit_status)
332 if (WIFEXITED (wait_status))
334 *exit_status = WEXITSTATUS (wait_status);
338 if (WIFSIGNALED (wait_status))
340 *exit_status = 0; /* ?? Don't know what else to say here. */
344 /* ??? Do we really need to consult the event state, too?
345 Assume the wait_state alone suffices. */
349 /* Perform a partial transfer to/from the specified object. For
350 memory transfers, fall back to the old memory xfer functions. */
353 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
354 const char *annex, gdb_byte *readbuf,
355 const gdb_byte *writebuf,
356 ULONGEST offset, LONGEST len)
360 case TARGET_OBJECT_MEMORY:
362 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
363 request that promises to be much more efficient in reading
364 and writing data in the traced process's address space. */
366 struct ptrace_io_desc piod;
368 /* NOTE: We assume that there are no distinct address spaces
369 for instruction and data. */
370 piod.piod_op = writebuf ? PIOD_WRITE_D : PIOD_READ_D;
371 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
372 piod.piod_offs = (void *) (long) offset;
376 if (ptrace (PT_IO, PIDGET (inferior_ptid), (caddr_t) &piod, 0) == 0)
377 /* Return the actual number of bytes read or written. */
378 return piod.piod_len;
379 /* If the PT_IO request is somehow not supported, fallback on
380 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
381 to indicate failure. */
389 PTRACE_TYPE_RET word;
390 unsigned char byte[sizeof (PTRACE_TYPE_RET)];
392 ULONGEST rounded_offset;
395 /* Round the start offset down to the next long word
397 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
399 /* Since ptrace will transfer a single word starting at that
400 rounded_offset the partial_len needs to be adjusted down to
401 that (remember this function only does a single transfer).
402 Should the required length be even less, adjust it down
404 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
405 if (partial_len > len)
410 /* If OFFSET:PARTIAL_LEN is smaller than
411 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
412 be needed. Read in the entire word. */
413 if (rounded_offset < offset
414 || (offset + partial_len
415 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
416 /* Need part of initial word -- fetch it. */
417 buffer.word = ptrace (PT_READ_I, PIDGET (inferior_ptid),
418 (PTRACE_TYPE_ARG3) (long) rounded_offset,
421 /* Copy data to be written over corresponding part of
423 memcpy (buffer.byte + (offset - rounded_offset),
424 writebuf, partial_len);
427 ptrace (PT_WRITE_D, PIDGET (inferior_ptid),
428 (PTRACE_TYPE_ARG3) (long) rounded_offset,
432 /* Using the appropriate one (I or D) is necessary for
433 Gould NP1, at least. */
435 ptrace (PT_WRITE_I, PIDGET (inferior_ptid),
436 (PTRACE_TYPE_ARG3) (long) rounded_offset,
445 buffer.word = ptrace (PT_READ_I, PIDGET (inferior_ptid),
446 (PTRACE_TYPE_ARG3) (long) rounded_offset, 0);
449 /* Copy appropriate bytes out of the buffer. */
450 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
456 case TARGET_OBJECT_UNWIND_TABLE:
459 case TARGET_OBJECT_AUXV:
462 case TARGET_OBJECT_WCOOKIE:
470 /* Check to see if the given thread is alive.
472 FIXME: Is kill() ever the right way to do this? I doubt it, but
473 for now we're going to try and be compatable with the old thread
477 inf_ptrace_thread_alive (ptid_t ptid)
479 pid_t pid = PIDGET (ptid);
481 return (kill (pid, 0) != -1);
484 /* Print status information about what we're accessing. */
487 inf_ptrace_files_info (struct target_ops *ignore)
489 printf_unfiltered (_("\tUsing the running image of %s %s.\n"),
490 attach_flag ? "attached" : "child",
491 target_pid_to_str (inferior_ptid));
495 inf_ptrace_pid_to_str (ptid_t ptid)
497 return normal_pid_to_str (ptid);
500 /* Create a prototype ptrace target. The client can override it with
504 inf_ptrace_target (void)
506 struct target_ops *t = inf_child_target ();
508 t->to_attach = inf_ptrace_attach;
509 t->to_detach = inf_ptrace_detach;
510 t->to_resume = inf_ptrace_resume;
511 t->to_wait = inf_ptrace_wait;
512 t->to_files_info = inf_ptrace_files_info;
513 t->to_kill = inf_ptrace_kill_inferior;
514 t->to_create_inferior = inf_ptrace_create_inferior;
515 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
516 t->to_thread_alive = inf_ptrace_thread_alive;
517 t->to_pid_to_str = inf_ptrace_pid_to_str;
518 t->to_stop = inf_ptrace_stop;
519 t->to_xfer_partial = inf_ptrace_xfer_partial;
521 t->to_has_exited = inf_ptrace_has_exited;
528 /* Pointer to a function that returns the oggset within the user area
529 where a particular register is stored. */
530 static CORE_ADDR (*inf_ptrace_register_u_offset)(int);
532 /* Fetch register REGNUM from the inferior. */
535 inf_ptrace_fetch_register (int regnum)
539 PTRACE_TYPE_RET *buf;
542 /* Cater for systems like GNU/Linux, that implement threads as
543 seperate processes. */
544 pid = ptid_get_lwp (inferior_ptid);
546 pid = ptid_get_pid (inferior_ptid);
548 /* This isn't really an address, but ptrace thinks of it as one. */
549 addr = inf_ptrace_register_u_offset (regnum);
550 size = register_size (current_gdbarch, regnum);
552 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
555 /* Read the register contents from the inferior a chuck at the time. */
556 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
559 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) addr, 0);
561 error (_("Couldn't read register %s (#%d): %s."), REGISTER_NAME (regnum),
562 regnum, safe_strerror (errno));
564 addr += sizeof (PTRACE_TYPE_RET);
566 regcache_raw_supply (current_regcache, regnum, buf);
569 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
570 for all registers. */
573 inf_ptrace_fetch_registers (int regnum)
576 for (regnum = 0; regnum < NUM_REGS; regnum++)
577 inf_ptrace_fetch_register (regnum);
579 inf_ptrace_fetch_register (regnum);
582 /* Store register REGNUM into the inferior. */
585 inf_ptrace_store_register (int regnum)
589 PTRACE_TYPE_RET *buf;
592 /* Cater for systems like GNU/Linux, that implement threads as
593 seperate processes. */
594 pid = ptid_get_lwp (inferior_ptid);
596 pid = ptid_get_pid (inferior_ptid);
598 /* This isn't really an address, but ptrace thinks of it as one. */
599 addr = inf_ptrace_register_u_offset (regnum);
600 size = register_size (current_gdbarch, regnum);
602 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
605 /* Write the register contents into the inferior a chunk at the time. */
606 regcache_raw_collect (current_regcache, regnum, buf);
607 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
610 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) addr, buf[i]);
612 error (_("Couldn't write register %s (#%d): %s."), REGISTER_NAME (regnum),
613 regnum, safe_strerror (errno));
615 addr += sizeof (PTRACE_TYPE_RET);
619 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
620 this for all registers. */
623 inf_ptrace_store_registers (int regnum)
626 for (regnum = 0; regnum < NUM_REGS; regnum++)
627 inf_ptrace_store_register (regnum);
629 inf_ptrace_store_register (regnum);
632 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
633 a function returning the offset within the user area where a
634 particular register is stored. */
637 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int))
639 struct target_ops *t = inf_ptrace_target();
641 gdb_assert (register_u_offset);
642 inf_ptrace_register_u_offset = register_u_offset;
643 t->to_fetch_registers = inf_ptrace_fetch_registers;
644 t->to_store_registers = inf_ptrace_store_registers;