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"
37 /* HACK: Save the ptrace ops returned by inf_ptrace_target. */
38 static struct target_ops *ptrace_ops_hack;
41 #ifdef PT_GET_PROCESS_STATE
44 inf_ptrace_follow_fork (struct target_ops *ops, int follow_child)
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);
61 if (ptrace (PT_GET_PROCESS_STATE, pid,
62 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
63 perror_with_name (("ptrace"));
65 gdb_assert (pe.pe_report_event == PTRACE_FORK);
66 fpid = pe.pe_other_pid;
70 inferior_ptid = pid_to_ptid (fpid);
71 detach_breakpoints (pid);
73 /* Reset breakpoints in the child as appropriate. */
74 follow_inferior_reset_breakpoints ();
76 if (ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
77 perror_with_name (("ptrace"));
81 inferior_ptid = pid_to_ptid (pid);
82 detach_breakpoints (fpid);
84 if (ptrace (PT_DETACH, fpid, (PTRACE_TYPE_ARG3)1, 0) == -1)
85 perror_with_name (("ptrace"));
91 #endif /* PT_GET_PROCESS_STATE */
94 /* Prepare to be traced. */
99 /* "Trace me, Dr. Memory!" */
100 ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
103 /* Start tracing PID. */
106 inf_ptrace_him (int pid)
108 push_target (ptrace_ops_hack);
110 /* On some targets, there must be some explicit synchronization
111 between the parent and child processes after the debugger
112 forks, and before the child execs the debuggee program. This
113 call basically gives permission for the child to exec. */
115 target_acknowledge_created_inferior (pid);
117 /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
118 be 1 or 2 depending on whether we're starting without or with a
120 startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
122 /* On some targets, there must be some explicit actions taken after
123 the inferior has been started up. */
124 target_post_startup_inferior (pid_to_ptid (pid));
127 /* Start a new inferior Unix child process. EXEC_FILE is the file to
128 run, ALLARGS is a string containing the arguments to the program.
129 ENV is the environment vector to pass. If FROM_TTY is non-zero, be
133 inf_ptrace_create_inferior (char *exec_file, char *allargs, char **env,
136 fork_inferior (exec_file, allargs, env, inf_ptrace_me, inf_ptrace_him,
140 #ifdef PT_GET_PROCESS_STATE
143 inf_ptrace_post_startup_inferior (ptid_t pid)
147 /* Set the initial event mask. */
148 memset (&pe, 0, sizeof pe);
149 pe.pe_set_event |= PTRACE_FORK;
150 if (ptrace (PT_SET_EVENT_MASK, ptid_get_pid (pid),
151 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
152 perror_with_name (("ptrace"));
157 /* Clean up a rotting corpse of an inferior after it died. */
160 inf_ptrace_mourn_inferior (void)
164 /* Wait just one more time to collect the inferior's exit status.
165 Do not check whether this succeeds though, since we may be
166 dealing with a process that we attached to. Such a process will
167 only report its exit status to its original parent. */
168 waitpid (ptid_get_pid (inferior_ptid), &status, 0);
170 unpush_target (ptrace_ops_hack);
171 generic_mourn_inferior ();
174 /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
175 be chatty about it. */
178 inf_ptrace_attach (char *args, int from_tty)
185 error_no_arg (_("process-id to attach"));
188 pid = strtol (args, &dummy, 0);
189 /* Some targets don't set errno on errors, grrr! */
190 if (pid == 0 && args == dummy)
191 error (_("Illegal process-id: %s."), args);
193 if (pid == getpid ()) /* Trying to masturbate? */
194 error (_("I refuse to debug myself!"));
198 exec_file = get_exec_file (0);
201 printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
202 target_pid_to_str (pid_to_ptid (pid)));
204 printf_unfiltered (_("Attaching to %s\n"),
205 target_pid_to_str (pid_to_ptid (pid)));
207 gdb_flush (gdb_stdout);
212 ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
214 perror_with_name (("ptrace"));
217 error (_("This system does not support attaching to a process"));
220 inferior_ptid = pid_to_ptid (pid);
221 push_target (ptrace_ops_hack);
224 #ifdef PT_GET_PROCESS_STATE
227 inf_ptrace_post_attach (int pid)
231 /* Set the initial event mask. */
232 memset (&pe, 0, sizeof pe);
233 pe.pe_set_event |= PTRACE_FORK;
234 if (ptrace (PT_SET_EVENT_MASK, pid,
235 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
236 perror_with_name (("ptrace"));
241 /* Detach from the inferior, optionally passing it the signal
242 specified by ARGS. If FROM_TTY is non-zero, be chatty about it. */
245 inf_ptrace_detach (char *args, int from_tty)
247 pid_t pid = ptid_get_pid (inferior_ptid);
252 char *exec_file = get_exec_file (0);
255 printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
256 target_pid_to_str (pid_to_ptid (pid)));
257 gdb_flush (gdb_stdout);
263 /* We'd better not have left any breakpoints in the program or it'll
264 die when it hits one. Also note that this may only work if we
265 previously attached to the inferior. It *might* work if we
266 started the process ourselves. */
268 ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, sig);
270 perror_with_name (("ptrace"));
273 error (_("This system does not support detaching from a process"));
276 inferior_ptid = null_ptid;
277 unpush_target (ptrace_ops_hack);
280 /* Kill the inferior. */
283 inf_ptrace_kill (void)
285 pid_t pid = ptid_get_pid (inferior_ptid);
291 ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
292 waitpid (pid, &status, 0);
294 target_mourn_inferior ();
297 /* Stop the inferior. */
300 inf_ptrace_stop (void)
302 /* Send a SIGINT to the process group. This acts just like the user
303 typed a ^C on the controlling terminal. Note that using a
304 negative process number in kill() is a System V-ism. The proper
305 BSD interface is killpg(). However, all modern BSDs support the
306 System V interface too. */
307 kill (-inferior_process_group, SIGINT);
310 /* Resume execution of thread PTID, or all threads if PTID is -1. If
311 STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
315 inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
317 pid_t pid = ptid_get_pid (ptid);
318 int request = PT_CONTINUE;
321 /* Resume all threads. Traditionally ptrace() only supports
322 single-threaded processes, so simply resume the inferior. */
323 pid = ptid_get_pid (inferior_ptid);
327 /* If this system does not support PT_STEP, a higher level
328 function will have called single_step() to transmute the step
329 request into a continue request (by setting breakpoints on
330 all possible successor instructions), so we don't have to
331 worry about that here. */
335 /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
336 where it was. If GDB wanted it to start some other way, we have
337 already written a new program counter value to the child. */
339 ptrace (request, pid, (PTRACE_TYPE_ARG3)1, target_signal_to_host (signal));
341 perror_with_name (("ptrace"));
344 /* Wait for the child specified by PTID to do something. Return the
345 process ID of the child, or MINUS_ONE_PTID in case of error; store
346 the status in *OURSTATUS. */
349 inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
352 int status, save_errno;
361 pid = waitpid (ptid_get_pid (ptid), &status, 0);
364 while (pid == -1 && errno == EINTR);
367 clear_sigint_trap ();
371 fprintf_unfiltered (gdb_stderr,
372 _("Child process unexpectedly missing: %s.\n"),
373 safe_strerror (save_errno));
375 /* Claim it exited with unknown signal. */
376 ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
377 ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
378 return minus_one_ptid;
381 /* Ignore terminated detached child processes. */
382 if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
387 #ifdef PT_GET_PROCESS_STATE
388 if (WIFSTOPPED (status))
393 if (ptrace (PT_GET_PROCESS_STATE, pid,
394 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
395 perror_with_name (("ptrace"));
397 switch (pe.pe_report_event)
400 ourstatus->kind = TARGET_WAITKIND_FORKED;
401 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
403 /* Make sure the other end of the fork is stopped too. */
404 fpid = waitpid (pe.pe_other_pid, &status, 0);
406 perror_with_name (("waitpid"));
408 if (ptrace (PT_GET_PROCESS_STATE, fpid,
409 (PTRACE_TYPE_ARG3)&pe, sizeof pe) == -1)
410 perror_with_name (("ptrace"));
412 gdb_assert (pe.pe_report_event == PTRACE_FORK);
413 gdb_assert (pe.pe_other_pid == pid);
414 if (fpid == ptid_get_pid (inferior_ptid))
416 ourstatus->value.related_pid = pid_to_ptid (pe.pe_other_pid);
417 return pid_to_ptid (fpid);
420 return pid_to_ptid (pid);
425 store_waitstatus (ourstatus, status);
426 return pid_to_ptid (pid);
429 /* Attempt a transfer all LEN bytes starting at OFFSET between the
430 inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
431 Return the number of bytes actually transferred. */
434 inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
435 const char *annex, gdb_byte *readbuf,
436 const gdb_byte *writebuf,
437 ULONGEST offset, LONGEST len)
439 pid_t pid = ptid_get_pid (inferior_ptid);
443 case TARGET_OBJECT_MEMORY:
445 /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
446 request that promises to be much more efficient in reading
447 and writing data in the traced process's address space. */
449 struct ptrace_io_desc piod;
451 /* NOTE: We assume that there are no distinct address spaces
452 for instruction and data. However, on OpenBSD 3.9 and
453 later, PIOD_WRITE_D doesn't allow changing memory that's
454 mapped read-only. Since most code segments will be
455 read-only, using PIOD_WRITE_D will prevent us from
456 inserting breakpoints, so we use PIOD_WRITE_I instead. */
457 piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
458 piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
459 piod.piod_offs = (void *) (long) offset;
463 if (ptrace (PT_IO, pid, (caddr_t)&piod, 0) == 0)
464 /* Return the actual number of bytes read or written. */
465 return piod.piod_len;
466 /* If the PT_IO request is somehow not supported, fallback on
467 using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
468 to indicate failure. */
476 PTRACE_TYPE_RET word;
477 gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
479 ULONGEST rounded_offset;
482 /* Round the start offset down to the next long word
484 rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
486 /* Since ptrace will transfer a single word starting at that
487 rounded_offset the partial_len needs to be adjusted down to
488 that (remember this function only does a single transfer).
489 Should the required length be even less, adjust it down
491 partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
492 if (partial_len > len)
497 /* If OFFSET:PARTIAL_LEN is smaller than
498 ROUNDED_OFFSET:WORDSIZE then a read/modify write will
499 be needed. Read in the entire word. */
500 if (rounded_offset < offset
501 || (offset + partial_len
502 < rounded_offset + sizeof (PTRACE_TYPE_RET)))
503 /* Need part of initial word -- fetch it. */
504 buffer.word = ptrace (PT_READ_I, pid,
505 (PTRACE_TYPE_ARG3)(uintptr_t)
508 /* Copy data to be written over corresponding part of
510 memcpy (buffer.byte + (offset - rounded_offset),
511 writebuf, partial_len);
514 ptrace (PT_WRITE_D, pid,
515 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
519 /* Using the appropriate one (I or D) is necessary for
520 Gould NP1, at least. */
522 ptrace (PT_WRITE_I, pid,
523 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
533 buffer.word = ptrace (PT_READ_I, pid,
534 (PTRACE_TYPE_ARG3)(uintptr_t)rounded_offset,
538 /* Copy appropriate bytes out of the buffer. */
539 memcpy (readbuf, buffer.byte + (offset - rounded_offset),
546 case TARGET_OBJECT_UNWIND_TABLE:
549 case TARGET_OBJECT_AUXV:
552 case TARGET_OBJECT_WCOOKIE:
560 /* Return non-zero if the thread specified by PTID is alive. */
563 inf_ptrace_thread_alive (ptid_t ptid)
565 /* ??? Is kill the right way to do this? */
566 return (kill (ptid_get_pid (ptid), 0) != -1);
569 /* Print status information about what we're accessing. */
572 inf_ptrace_files_info (struct target_ops *ignore)
574 printf_filtered (_("\tUsing the running image of %s %s.\n"),
575 attach_flag ? "attached" : "child",
576 target_pid_to_str (inferior_ptid));
579 /* Create a prototype ptrace target. The client can override it with
583 inf_ptrace_target (void)
585 struct target_ops *t = inf_child_target ();
587 t->to_attach = inf_ptrace_attach;
588 t->to_detach = inf_ptrace_detach;
589 t->to_resume = inf_ptrace_resume;
590 t->to_wait = inf_ptrace_wait;
591 t->to_files_info = inf_ptrace_files_info;
592 t->to_kill = inf_ptrace_kill;
593 t->to_create_inferior = inf_ptrace_create_inferior;
594 #ifdef PT_GET_PROCESS_STATE
595 t->to_follow_fork = inf_ptrace_follow_fork;
596 t->to_post_startup_inferior = inf_ptrace_post_startup_inferior;
597 t->to_post_attach = inf_ptrace_post_attach;
599 t->to_mourn_inferior = inf_ptrace_mourn_inferior;
600 t->to_thread_alive = inf_ptrace_thread_alive;
601 t->to_pid_to_str = normal_pid_to_str;
602 t->to_stop = inf_ptrace_stop;
603 t->to_xfer_partial = inf_ptrace_xfer_partial;
610 /* Pointer to a function that returns the offset within the user area
611 where a particular register is stored. */
612 static CORE_ADDR (*inf_ptrace_register_u_offset)(struct gdbarch *, int, int);
614 /* Fetch register REGNUM from the inferior. */
617 inf_ptrace_fetch_register (struct regcache *regcache, int regnum)
619 struct gdbarch *gdbarch = get_regcache_arch (regcache);
622 PTRACE_TYPE_RET *buf;
625 /* This isn't really an address, but ptrace thinks of it as one. */
626 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 0);
627 if (addr == (CORE_ADDR)-1
628 || gdbarch_cannot_fetch_register (gdbarch, regnum))
630 regcache_raw_supply (regcache, regnum, NULL);
634 /* Cater for systems like GNU/Linux, that implement threads as
635 separate processes. */
636 pid = ptid_get_lwp (inferior_ptid);
638 pid = ptid_get_pid (inferior_ptid);
640 size = register_size (gdbarch, regnum);
641 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
644 /* Read the register contents from the inferior a chunk at a time. */
645 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
648 buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, 0);
650 error (_("Couldn't read register %s (#%d): %s."),
651 gdbarch_register_name (gdbarch, regnum),
652 regnum, safe_strerror (errno));
654 addr += sizeof (PTRACE_TYPE_RET);
656 regcache_raw_supply (regcache, regnum, buf);
659 /* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
660 for all registers. */
663 inf_ptrace_fetch_registers (struct regcache *regcache, int regnum)
667 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
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)
679 struct gdbarch *gdbarch = get_regcache_arch (regcache);
682 PTRACE_TYPE_RET *buf;
685 /* This isn't really an address, but ptrace thinks of it as one. */
686 addr = inf_ptrace_register_u_offset (gdbarch, regnum, 1);
687 if (addr == (CORE_ADDR)-1
688 || gdbarch_cannot_store_register (gdbarch, regnum))
691 /* Cater for systems like GNU/Linux, that implement threads as
692 separate processes. */
693 pid = ptid_get_lwp (inferior_ptid);
695 pid = ptid_get_pid (inferior_ptid);
697 size = register_size (gdbarch, regnum);
698 gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
701 /* Write the register contents into the inferior a chunk at a time. */
702 regcache_raw_collect (regcache, regnum, buf);
703 for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
706 ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3)(uintptr_t)addr, buf[i]);
708 error (_("Couldn't write register %s (#%d): %s."),
709 gdbarch_register_name (gdbarch, regnum),
710 regnum, safe_strerror (errno));
712 addr += sizeof (PTRACE_TYPE_RET);
716 /* Store register REGNUM back into the inferior. If REGNUM is -1, do
717 this for all registers. */
720 inf_ptrace_store_registers (struct regcache *regcache, int regnum)
724 regnum < gdbarch_num_regs (get_regcache_arch (regcache));
726 inf_ptrace_store_register (regcache, regnum);
728 inf_ptrace_store_register (regcache, regnum);
731 /* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
732 a function returning the offset within the user area where a
733 particular register is stored. */
736 inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)
737 (struct gdbarch *, int, int))
739 struct target_ops *t = inf_ptrace_target();
741 gdb_assert (register_u_offset);
742 inf_ptrace_register_u_offset = register_u_offset;
743 t->to_fetch_registers = inf_ptrace_fetch_registers;
744 t->to_store_registers = inf_ptrace_store_registers;