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
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;
77 struct thread_info *tp;
79 /* Otherwise, deleting the parent would get rid of this
81 last_tp->step_resume_breakpoint = NULL;
83 /* Before detaching from the parent, remove all breakpoints from
85 detach_breakpoints (pid);
87 if (ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
88 perror_with_name (("ptrace"));
90 /* Switch inferior_ptid out of the parent's way. */
91 inferior_ptid = pid_to_ptid (fpid);
93 /* Delete the parent. */
94 detach_inferior (pid);
98 tp = add_thread_silent (inferior_ptid);
100 tp->step_resume_breakpoint = step_resume_breakpoint;
101 tp->step_range_start = step_range_start;
102 tp->step_range_end = step_range_end;
103 tp->step_frame_id = step_frame_id;
105 /* Reset breakpoints in the child as appropriate. */
106 follow_inferior_reset_breakpoints ();
110 inferior_ptid = pid_to_ptid (pid);
111 detach_breakpoints (fpid);
113 if (ptrace (PT_DETACH, fpid, (PTRACE_TYPE_ARG3)1, 0) == -1)
114 perror_with_name (("ptrace"));
115 detach_inferior (pid);
121 #endif /* PT_GET_PROCESS_STATE */
124 /* Prepare to be traced. */
129 /* "Trace me, Dr. Memory!" */
130 ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
133 /* Start a new inferior Unix child process. EXEC_FILE is the file to
134 run, ALLARGS is a string containing the arguments to the program.
135 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
139 inf_ptrace_create_inferior (struct target_ops *ops,
140 char *exec_file, char *allargs, char **env,
145 pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
150 /* On some targets, there must be some explicit synchronization
151 between the parent and child processes after the debugger
152 forks, and before the child execs the debuggee program. This
153 call basically gives permission for the child to exec. */
155 target_acknowledge_created_inferior (pid);
157 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
158 be 1 or 2 depending on whether we're starting without or with a
160 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
162 /* On some targets, there must be some explicit actions taken after
163 the inferior has been started up. */
164 target_post_startup_inferior (pid_to_ptid (pid));
167 #ifdef PT_GET_PROCESS_STATE
170 inf_ptrace_post_startup_inferior (ptid_t pid)
174 /* Set the initial event mask. */
175 memset (&pe, 0, sizeof pe);
176 pe.pe_set_event |= PTRACE_FORK;
177 if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
178 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
179 perror_with_name (("ptrace"));
184 /* Clean up a rotting corpse of an inferior after it died. */
187 inf_ptrace_mourn_inferior (struct target_ops *ops)
191 /* Wait just one more time to collect the inferior's exit status.
192 Do not check whether this succeeds though, since we may be
193 dealing with a process that we attached to. Such a process will
194 only report its exit status to its original parent. */
195 waitpid (ptid_get_pid (inferior_ptid), &status, 0);
198 generic_mourn_inferior ();
201 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
202 be chatty about it. */
205 inf_ptrace_attach (struct target_ops *ops, char *args, int from_tty)
210 struct inferior *inf;
213 error_no_arg (_("process-id to attach"));
216 pid = strtol (args, &dummy, 0);
217 /* Some targets don't set errno on errors, grrr! */
218 if (pid == 0 && args == dummy)
219 error (_("Illegal process-id: %s."), args);
221 if (pid == getpid ()) /* Trying to masturbate? */
222 error (_("I refuse to debug myself!"));
226 exec_file = get_exec_file (0);
229 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
230 target_pid_to_str (pid_to_ptid (pid)));
232 printf_unfiltered (_("Attaching to %s\n"),
233 target_pid_to_str (pid_to_ptid (pid)));
235 gdb_flush (gdb_stdout);
240 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
242 perror_with_name (("ptrace"));
244 error (_("This system does not support attaching to a process"));
247 inferior_ptid = pid_to_ptid (pid);
249 inf = add_inferior (pid);
250 inf->attach_flag = 1;
252 /* Always add a main thread. If some target extends the ptrace
253 target, it should decorate the ptid later with more info. */
254 add_thread_silent (inferior_ptid);
259 #ifdef PT_GET_PROCESS_STATE
262 inf_ptrace_post_attach (int pid)
266 /* Set the initial event mask. */
267 memset (&pe, 0, sizeof pe);
268 pe.pe_set_event |= PTRACE_FORK;
269 if (ptrace (PT_SET_EVENT_MASK, pid,
270 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
271 perror_with_name (("ptrace"));
276 /* Detach from the inferior, optionally passing it the signal
277 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
280 inf_ptrace_detach (struct target_ops *ops, char *args, int from_tty)
282 pid_t pid = ptid_get_pid (inferior_ptid);
287 char *exec_file = get_exec_file (0);
290 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
291 target_pid_to_str (pid_to_ptid (pid)));
292 gdb_flush (gdb_stdout);
298 /* We'd better not have left any breakpoints in the program or it'll
299 die when it hits one. Also note that this may only work if we
300 previously attached to the inferior. It *might* work if we
301 started the process ourselves. */
303 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
305 perror_with_name (("ptrace"));
307 error (_("This system does not support detaching from a process"));
310 inferior_ptid = null_ptid;
311 detach_inferior (pid);
315 /* Kill the inferior. */
318 inf_ptrace_kill (void)
320 pid_t pid = ptid_get_pid (inferior_ptid);
326 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
327 waitpid (pid, &status, 0);
329 target_mourn_inferior ();
332 /* Stop the inferior. */
335 inf_ptrace_stop (ptid_t ptid)
337 /* Send a SIGINT to the process group. This acts just like the user
338 typed a ^C on the controlling terminal. Note that using a
339 negative process number in kill() is a System V-ism. The proper
340 BSD interface is killpg(). However, all modern BSDs support the
341 System V interface too. */
342 kill (-inferior_process_group, SIGINT);
345 /* Resume execution of thread PTID, or all threads if PTID is -1. If
346 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
350 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
352 pid_t pid = ptid_get_pid (ptid);
353 int request = PT_CONTINUE;
356 /* Resume all threads. Traditionally ptrace() only supports
357 single-threaded processes, so simply resume the inferior. */
358 pid = ptid_get_pid (inferior_ptid);
362 /* If this system does not support PT_STEP, a higher level
363 function will have called single_step() to transmute the step
364 request into a continue request (by setting breakpoints on
365 all possible successor instructions), so we don't have to
366 worry about that here. */
370 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
371 where it was. If GDB wanted it to start some other way, we have
372 already written a new program counter value to the child. */
374 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
376 perror_with_name (("ptrace"));
379 /* Wait for the child specified by PTID to do something. Return the
380 process ID of the child, or MINUS_ONE_PTID in case of error; store
381 the status in *OURSTATUS. */
384 inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
387 int status, save_errno;
395 pid = waitpid (ptid_get_pid (ptid), &status, 0);
398 while (pid == -1 && errno == EINTR);
400 clear_sigint_trap ();
404 fprintf_unfiltered (gdb_stderr,
405 _("Child process unexpectedly missing: %s.\n"),
406 safe_strerror (save_errno));
408 /* Claim it exited with unknown signal. */
409 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
410 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
411 return inferior_ptid;
414 /* Ignore terminated detached child processes. */
415 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
420 #ifdef PT_GET_PROCESS_STATE
421 if (WIFSTOPPED (status))
426 if (ptrace (PT_GET_PROCESS_STATE, pid,
427 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
428 perror_with_name (("ptrace"));
430 switch (pe.pe_report_event)
433 ourstatus->kind = TARGET_WAITKIND_FORKED;
434 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
436 /* Make sure the other end of the fork is stopped too. */
437 fpid = waitpid (pe.pe_other_pid, &status, 0);
439 perror_with_name (("waitpid"));
441 if (ptrace (PT_GET_PROCESS_STATE, fpid,
442 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
443 perror_with_name (("ptrace"));
445 gdb_assert (pe.pe_report_event == PTRACE_FORK);
446 gdb_assert (pe.pe_other_pid == pid);
447 if (fpid == ptid_get_pid (inferior_ptid))
449 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
450 return pid_to_ptid (fpid);
453 return pid_to_ptid (pid);
458 store_waitstatus (ourstatus, status);
459 return pid_to_ptid (pid);
462 /* Attempt a transfer all LEN bytes starting at OFFSET between the
463 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
464 Return the number of bytes actually transferred. */
467 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
468 const char *annex, gdb_byte *readbuf,
469 const gdb_byte *writebuf,
470 ULONGEST offset, LONGEST len)
472 pid_t pid = ptid_get_pid (inferior_ptid);
476 case TARGET_OBJECT_MEMORY:
478 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
479 request that promises to be much more efficient in reading
480 and writing data in the traced process's address space. */
482 struct ptrace_io_desc piod;
484 /* NOTE: We assume that there are no distinct address spaces
485 for instruction and data. However, on OpenBSD 3.9 and
486 later, PIOD_WRITE_D doesn't allow changing memory that's
487 mapped read-only. Since most code segments will be
488 read-only, using PIOD_WRITE_D will prevent us from
489 inserting breakpoints, so we use PIOD_WRITE_I instead. */
490 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
491 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
492 piod.piod_offs = (void *) (long) offset;
496 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
497 /* Return the actual number of bytes read or written. */
498 return piod.piod_len;
499 /* If the PT_IO request is somehow not supported, fallback on
500 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
501 to indicate failure. */
509 PTRACE_TYPE_RET word;
510 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
512 ULONGEST rounded_offset;
515 /* Round the start offset down to the next long word
517 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
519 /* Since ptrace will transfer a single word starting at that
520 rounded_offset the partial_len needs to be adjusted down to
521 that (remember this function only does a single transfer).
522 Should the required length be even less, adjust it down
524 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
525 if (partial_len > len)
530 /* If OFFSET:PARTIAL_LEN is smaller than
531 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
532 be needed. Read in the entire word. */
533 if (rounded_offset < offset
534 || (offset + partial_len
535 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
536 /* Need part of initial word -- fetch it. */
537 buffer.word = ptrace (PT_READ_I, pid,
538 (PTRACE_TYPE_ARG3)(uintptr_t)
541 /* Copy data to be written over corresponding part of
543 memcpy (buffer.byte + (offset - rounded_offset),
544 writebuf, partial_len);
547 ptrace (PT_WRITE_D, pid,
548 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
552 /* Using the appropriate one (I or D) is necessary for
553 Gould NP1, at least. */
555 ptrace (PT_WRITE_I, pid,
556 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
566 buffer.word = ptrace (PT_READ_I, pid,
567 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
571 /* Copy appropriate bytes out of the buffer. */
572 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
579 case TARGET_OBJECT_UNWIND_TABLE:
582 case TARGET_OBJECT_AUXV:
585 case TARGET_OBJECT_WCOOKIE:
593 /* Return non-zero if the thread specified by PTID is alive. */
596 inf_ptrace_thread_alive (ptid_t ptid)
598 /* ??? Is kill the right way to do this? */
599 return (kill (ptid_get_pid (ptid), 0) != -1);
602 /* Print status information about what we're accessing. */
605 inf_ptrace_files_info (struct target_ops *ignore)
607 struct inferior *inf = current_inferior ();
609 printf_filtered (_("\tUsing the running image of %s %s.\n"),
610 inf->attach_flag ? "attached" : "child",
611 target_pid_to_str (inferior_ptid));
614 /* Create a prototype ptrace target. The client can override it with
618 inf_ptrace_target (void)
620 struct target_ops *t = inf_child_target ();
622 t->to_attach = inf_ptrace_attach;
623 t->to_detach = inf_ptrace_detach;
624 t->to_resume = inf_ptrace_resume;
625 t->to_wait = inf_ptrace_wait;
626 t->to_files_info = inf_ptrace_files_info;
627 t->to_kill = inf_ptrace_kill;
628 t->to_create_inferior = inf_ptrace_create_inferior;
629 #ifdef PT_GET_PROCESS_STATE
630 t->to_follow_fork = inf_ptrace_follow_fork;
631 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
632 t->to_post_attach = inf_ptrace_post_attach;
634 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
635 t->to_thread_alive = inf_ptrace_thread_alive;
636 t->to_pid_to_str = normal_pid_to_str;
637 t->to_stop = inf_ptrace_stop;
638 t->to_xfer_partial = inf_ptrace_xfer_partial;
644 /* Pointer to a function that returns the offset within the user area
645 where a particular register is stored. */
646 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
648 /* Fetch register REGNUM from the inferior. */
651 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
653 struct gdbarch *gdbarch = get_regcache_arch (regcache);
656 PTRACE_TYPE_RET *buf;
659 /* This isn't really an address, but ptrace thinks of it as one. */
660 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
661 if (addr == (CORE_ADDR)-1
662 || gdbarch_cannot_fetch_register (gdbarch, regnum))
664 regcache_raw_supply (regcache, regnum, NULL);
668 /* Cater for systems like GNU/Linux, that implement threads as
669 separate processes. */
670 pid = ptid_get_lwp (inferior_ptid);
672 pid = ptid_get_pid (inferior_ptid);
674 size = register_size (gdbarch, regnum);
675 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
678 /* Read the register contents from the inferior a chunk at a time. */
679 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
682 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
684 error (_("Couldn't read register %s (#%d): %s."),
685 gdbarch_register_name (gdbarch, regnum),
686 regnum, safe_strerror (errno));
688 addr += sizeof (PTRACE_TYPE_RET);
690 regcache_raw_supply (regcache, regnum, buf);
693 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
694 for all registers. */
697 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
701 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
703 inf_ptrace_fetch_register (regcache, regnum);
705 inf_ptrace_fetch_register (regcache, regnum);
708 /* Store register REGNUM into the inferior. */
711 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
713 struct gdbarch *gdbarch = get_regcache_arch (regcache);
716 PTRACE_TYPE_RET *buf;
719 /* This isn't really an address, but ptrace thinks of it as one. */
720 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
721 if (addr == (CORE_ADDR)-1
722 || gdbarch_cannot_store_register (gdbarch, regnum))
725 /* Cater for systems like GNU/Linux, that implement threads as
726 separate processes. */
727 pid = ptid_get_lwp (inferior_ptid);
729 pid = ptid_get_pid (inferior_ptid);
731 size = register_size (gdbarch, regnum);
732 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
735 /* Write the register contents into the inferior a chunk at a time. */
736 regcache_raw_collect (regcache, regnum, buf);
737 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
740 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
742 error (_("Couldn't write register %s (#%d): %s."),
743 gdbarch_register_name (gdbarch, regnum),
744 regnum, safe_strerror (errno));
746 addr += sizeof (PTRACE_TYPE_RET);
750 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
751 this for all registers. */
754 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
758 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
760 inf_ptrace_store_register (regcache, regnum);
762 inf_ptrace_store_register (regcache, regnum);
765 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
766 a function returning the offset within the user area where a
767 particular register is stored. */
770 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
771 (struct gdbarch *, int, int))
773 struct target_ops *t = inf_ptrace_target();
775 gdb_assert (register_u_offset);
776 inf_ptrace_register_u_offset = register_u_offset;
777 t->to_fetch_registers = inf_ptrace_fetch_registers;
778 t->to_store_registers = inf_ptrace_store_registers;