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 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. */
31 #include "gdb_stdint.h"
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);
227 #ifdef PT_GET_PROCESS_STATE
230 inf_ptrace_post_attach (int pid)
234 /* Set the initial event mask. */
235 memset (&pe, 0, sizeof pe);
236 pe.pe_set_event |= PTRACE_FORK;
237 if (ptrace (PT_SET_EVENT_MASK, pid,
238 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
239 perror_with_name (("ptrace"));
244 /* Detach from the inferior, optionally passing it the signal
245 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
248 inf_ptrace_detach (char *args, int from_tty)
250 pid_t pid = ptid_get_pid (inferior_ptid);
255 char *exec_file = get_exec_file (0);
258 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
259 target_pid_to_str (pid_to_ptid (pid)));
260 gdb_flush (gdb_stdout);
266 /* We'd better not have left any breakpoints in the program or it'll
267 die when it hits one. Also note that this may only work if we
268 previously attached to the inferior. It *might* work if we
269 started the process ourselves. */
271 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
273 perror_with_name (("ptrace"));
276 error (_("This system does not support detaching from a process"));
279 inferior_ptid = null_ptid;
280 unpush_target (ptrace_ops_hack);
283 /* Kill the inferior. */
286 inf_ptrace_kill (void)
288 pid_t pid = ptid_get_pid (inferior_ptid);
294 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
295 waitpid (pid, &status, 0);
297 target_mourn_inferior ();
300 /* Stop the inferior. */
303 inf_ptrace_stop (void)
305 /* Send a SIGINT to the process group. This acts just like the user
306 typed a ^C on the controlling terminal. Note that using a
307 negative process number in kill() is a System V-ism. The proper
308 BSD interface is killpg(). However, all modern BSDs support the
309 System V interface too. */
310 kill (-inferior_process_group, SIGINT);
313 /* Resume execution of thread PTID, or all threads if PTID is -1. If
314 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
318 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
320 pid_t pid = ptid_get_pid (ptid);
321 int request = PT_CONTINUE;
324 /* Resume all threads. Traditionally ptrace() only supports
325 single-threaded processes, so simply resume the inferior. */
326 pid = ptid_get_pid (inferior_ptid);
330 /* If this system does not support PT_STEP, a higher level
331 function will have called single_step() to transmute the step
332 request into a continue request (by setting breakpoints on
333 all possible successor instructions), so we don't have to
334 worry about that here. */
338 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
339 where it was. If GDB wanted it to start some other way, we have
340 already written a new program counter value to the child. */
342 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
344 perror_with_name (("ptrace"));
347 /* Wait for the child specified by PTID to do something. Return the
348 process ID of the child, or MINUS_ONE_PTID in case of error; store
349 the status in *OURSTATUS. */
352 inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
355 int status, save_errno;
364 pid = waitpid (ptid_get_pid (ptid), &status, 0);
367 while (pid == -1 && errno == EINTR);
370 clear_sigint_trap ();
374 fprintf_unfiltered (gdb_stderr,
375 _("Child process unexpectedly missing: %s.\n"),
376 safe_strerror (save_errno));
378 /* Claim it exited with unknown signal. */
379 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
380 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
381 return minus_one_ptid;
384 /* Ignore terminated detached child processes. */
385 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
390 #ifdef PT_GET_PROCESS_STATE
391 if (WIFSTOPPED (status))
396 if (ptrace (PT_GET_PROCESS_STATE, pid,
397 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
398 perror_with_name (("ptrace"));
400 switch (pe.pe_report_event)
403 ourstatus->kind = TARGET_WAITKIND_FORKED;
404 ourstatus->value.related_pid = pe.pe_other_pid;
406 /* Make sure the other end of the fork is stopped too. */
407 fpid = waitpid (pe.pe_other_pid, &status, 0);
409 perror_with_name (("waitpid"));
411 if (ptrace (PT_GET_PROCESS_STATE, fpid,
412 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
413 perror_with_name (("ptrace"));
415 gdb_assert (pe.pe_report_event == PTRACE_FORK);
416 gdb_assert (pe.pe_other_pid == pid);
417 if (fpid == ptid_get_pid (inferior_ptid))
419 ourstatus->value.related_pid = pe.pe_other_pid;
420 return pid_to_ptid (fpid);
423 return pid_to_ptid (pid);
428 store_waitstatus (ourstatus, status);
429 return pid_to_ptid (pid);
432 /* Attempt a transfer all LEN bytes starting at OFFSET between the
433 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
434 Return the number of bytes actually transferred. */
437 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
438 const char *annex, gdb_byte *readbuf,
439 const gdb_byte *writebuf,
440 ULONGEST offset, LONGEST len)
442 pid_t pid = ptid_get_pid (inferior_ptid);
446 case TARGET_OBJECT_MEMORY:
448 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
449 request that promises to be much more efficient in reading
450 and writing data in the traced process's address space. */
452 struct ptrace_io_desc piod;
454 /* NOTE: We assume that there are no distinct address spaces
455 for instruction and data. However, on OpenBSD 3.9 and
456 later, PIOD_WRITE_D doesn't allow changing memory that's
457 mapped read-only. Since most code segments will be
458 read-only, using PIOD_WRITE_D will prevent us from
459 inserting breakpoints, so we use PIOD_WRITE_I instead. */
460 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
461 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
462 piod.piod_offs = (void *) (long) offset;
466 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
467 /* Return the actual number of bytes read or written. */
468 return piod.piod_len;
469 /* If the PT_IO request is somehow not supported, fallback on
470 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
471 to indicate failure. */
479 PTRACE_TYPE_RET word;
480 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
482 ULONGEST rounded_offset;
485 /* Round the start offset down to the next long word
487 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
489 /* Since ptrace will transfer a single word starting at that
490 rounded_offset the partial_len needs to be adjusted down to
491 that (remember this function only does a single transfer).
492 Should the required length be even less, adjust it down
494 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
495 if (partial_len > len)
500 /* If OFFSET:PARTIAL_LEN is smaller than
501 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
502 be needed. Read in the entire word. */
503 if (rounded_offset < offset
504 || (offset + partial_len
505 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
506 /* Need part of initial word -- fetch it. */
507 buffer.word = ptrace (PT_READ_I, pid,
508 (PTRACE_TYPE_ARG3)(uintptr_t)
511 /* Copy data to be written over corresponding part of
513 memcpy (buffer.byte + (offset - rounded_offset),
514 writebuf, partial_len);
517 ptrace (PT_WRITE_D, pid,
518 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
522 /* Using the appropriate one (I or D) is necessary for
523 Gould NP1, at least. */
525 ptrace (PT_WRITE_I, pid,
526 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
536 buffer.word = ptrace (PT_READ_I, pid,
537 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
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)(struct gdbarch *, int, int);
617 /* Fetch register REGNUM from the inferior. */
620 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
624 PTRACE_TYPE_RET *buf;
627 /* This isn't really an address, but ptrace thinks of it as one. */
628 addr = inf_ptrace_register_u_offset (current_gdbarch, regnum, 0);
629 if (addr == (CORE_ADDR)-1
630 || gdbarch_cannot_fetch_register (current_gdbarch, regnum))
632 regcache_raw_supply (regcache, regnum, NULL);
636 /* Cater for systems like GNU/Linux, that implement threads as
637 separate processes. */
638 pid = ptid_get_lwp (inferior_ptid);
640 pid = ptid_get_pid (inferior_ptid);
642 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)(uintptr_t)addr, 0);
652 error (_("Couldn't read register %s (#%d): %s."),
653 gdbarch_register_name (current_gdbarch, regnum),
654 regnum, safe_strerror (errno));
656 addr += sizeof (PTRACE_TYPE_RET);
658 regcache_raw_supply (regcache, regnum, buf);
661 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
662 for all registers. */
665 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
668 for (regnum = 0; regnum < gdbarch_num_regs (current_gdbarch); regnum++)
669 inf_ptrace_fetch_register (regcache, regnum);
671 inf_ptrace_fetch_register (regcache, regnum);
674 /* Store register REGNUM into the inferior. */
677 inf_ptrace_store_register (const struct regcache *regcache, int regnum)
681 PTRACE_TYPE_RET *buf;
684 /* This isn't really an address, but ptrace thinks of it as one. */
685 addr = inf_ptrace_register_u_offset (current_gdbarch, regnum, 1);
686 if (addr == (CORE_ADDR)-1
687 || gdbarch_cannot_store_register (current_gdbarch, regnum))
690 /* Cater for systems like GNU/Linux, that implement threads as
691 separate processes. */
692 pid = ptid_get_lwp (inferior_ptid);
694 pid = ptid_get_pid (inferior_ptid);
696 size = register_size (current_gdbarch, regnum);
697 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
700 /* Write the register contents into the inferior a chunk at a time. */
701 regcache_raw_collect (regcache, regnum, buf);
702 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
705 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
707 error (_("Couldn't write register %s (#%d): %s."),
708 gdbarch_register_name (current_gdbarch, regnum),
709 regnum, safe_strerror (errno));
711 addr += sizeof (PTRACE_TYPE_RET);
715 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
716 this for all registers. */
719 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
722 for (regnum = 0; regnum < gdbarch_num_regs (current_gdbarch); regnum++)
723 inf_ptrace_store_register (regcache, regnum);
725 inf_ptrace_store_register (regcache, regnum);
728 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
729 a function returning the offset within the user area where a
730 particular register is stored. */
733 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
734 (struct gdbarch *, int, int))
736 struct target_ops *t = inf_ptrace_target();
738 gdb_assert (register_u_offset);
739 inf_ptrace_register_u_offset = register_u_offset;
740 t->to_fetch_registers = inf_ptrace_fetch_registers;
741 t->to_store_registers = inf_ptrace_store_registers;