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- /* Low-level child interface to ptrace.
- Copyright (C) 1988-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #include "defs.h"
- #include "command.h"
- #include "inferior.h"
- #include "terminal.h"
- #include "gdbcore.h"
- #include "regcache.h"
- #include "nat/gdb_ptrace.h"
- #include "gdbsupport/gdb_wait.h"
- #include <signal.h>
- #include "inf-ptrace.h"
- #include "inf-child.h"
- #include "gdbthread.h"
- #include "nat/fork-inferior.h"
- #include "utils.h"
- #include "gdbarch.h"
- static PTRACE_TYPE_RET
- gdb_ptrace (PTRACE_TYPE_ARG1 request, ptid_t ptid, PTRACE_TYPE_ARG3 addr,
- PTRACE_TYPE_ARG4 data)
- {
- #ifdef __NetBSD__
- return ptrace (request, ptid.pid (), addr, data);
- #else
- pid_t pid = get_ptrace_pid (ptid);
- return ptrace (request, pid, addr, data);
- #endif
- }
- /* The event pipe registered as a waitable file in the event loop. */
- event_pipe inf_ptrace_target::m_event_pipe;
- inf_ptrace_target::~inf_ptrace_target ()
- {}
- /* Prepare to be traced. */
- static void
- inf_ptrace_me (void)
- {
- /* "Trace me, Dr. Memory!" */
- if (ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3) 0, 0) < 0)
- trace_start_error_with_name ("ptrace");
- }
- /* Start a new inferior Unix child process. EXEC_FILE is the file to
- run, ALLARGS is a string containing the arguments to the program.
- ENV is the environment vector to pass. If FROM_TTY is non-zero, be
- chatty about it. */
- void
- inf_ptrace_target::create_inferior (const char *exec_file,
- const std::string &allargs,
- char **env, int from_tty)
- {
- inferior *inf = current_inferior ();
- /* Do not change either targets above or the same target if already present.
- The reason is the target stack is shared across multiple inferiors. */
- int ops_already_pushed = inf->target_is_pushed (this);
- target_unpush_up unpusher;
- if (! ops_already_pushed)
- {
- /* Clear possible core file with its process_stratum. */
- inf->push_target (this);
- unpusher.reset (this);
- }
- pid_t pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
- NULL, NULL, NULL);
- ptid_t ptid (pid);
- /* We have something that executes now. We'll be running through
- the shell at this point (if startup-with-shell is true), but the
- pid shouldn't change. */
- thread_info *thr = add_thread_silent (this, ptid);
- switch_to_thread (thr);
- unpusher.release ();
- gdb_startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED);
- /* On some targets, there must be some explicit actions taken after
- the inferior has been started up. */
- post_startup_inferior (ptid);
- }
- /* Clean up a rotting corpse of an inferior after it died. */
- void
- inf_ptrace_target::mourn_inferior ()
- {
- int status;
- /* Wait just one more time to collect the inferior's exit status.
- Do not check whether this succeeds though, since we may be
- dealing with a process that we attached to. Such a process will
- only report its exit status to its original parent. */
- waitpid (inferior_ptid.pid (), &status, 0);
- inf_child_target::mourn_inferior ();
- }
- /* Attach to the process specified by ARGS. If FROM_TTY is non-zero,
- be chatty about it. */
- void
- inf_ptrace_target::attach (const char *args, int from_tty)
- {
- inferior *inf = current_inferior ();
- /* Do not change either targets above or the same target if already present.
- The reason is the target stack is shared across multiple inferiors. */
- int ops_already_pushed = inf->target_is_pushed (this);
- pid_t pid = parse_pid_to_attach (args);
- if (pid == getpid ()) /* Trying to masturbate? */
- error (_("I refuse to debug myself!"));
- target_unpush_up unpusher;
- if (! ops_already_pushed)
- {
- /* target_pid_to_str already uses the target. Also clear possible core
- file with its process_stratum. */
- inf->push_target (this);
- unpusher.reset (this);
- }
- target_announce_attach (from_tty, pid);
- #ifdef PT_ATTACH
- errno = 0;
- ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3)0, 0);
- if (errno != 0)
- perror_with_name (("ptrace"));
- #else
- error (_("This system does not support attaching to a process"));
- #endif
- inferior_appeared (inf, pid);
- inf->attach_flag = 1;
- /* Always add a main thread. If some target extends the ptrace
- target, it should decorate the ptid later with more info. */
- thread_info *thr = add_thread_silent (this, ptid_t (pid));
- switch_to_thread (thr);
- /* Don't consider the thread stopped until we've processed its
- initial SIGSTOP stop. */
- set_executing (this, thr->ptid, true);
- unpusher.release ();
- }
- /* Detach from the inferior. If FROM_TTY is non-zero, be chatty about it. */
- void
- inf_ptrace_target::detach (inferior *inf, int from_tty)
- {
- pid_t pid = inferior_ptid.pid ();
- target_announce_detach (from_tty);
- #ifdef PT_DETACH
- /* We'd better not have left any breakpoints in the program or it'll
- die when it hits one. Also note that this may only work if we
- previously attached to the inferior. It *might* work if we
- started the process ourselves. */
- errno = 0;
- ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3)1, 0);
- if (errno != 0)
- perror_with_name (("ptrace"));
- #else
- error (_("This system does not support detaching from a process"));
- #endif
- detach_success (inf);
- }
- /* See inf-ptrace.h. */
- void
- inf_ptrace_target::detach_success (inferior *inf)
- {
- switch_to_no_thread ();
- detach_inferior (inf);
- maybe_unpush_target ();
- }
- /* Kill the inferior. */
- void
- inf_ptrace_target::kill ()
- {
- pid_t pid = inferior_ptid.pid ();
- int status;
- if (pid == 0)
- return;
- ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3)0, 0);
- waitpid (pid, &status, 0);
- target_mourn_inferior (inferior_ptid);
- }
- #ifndef __NetBSD__
- /* See inf-ptrace.h. */
- pid_t
- get_ptrace_pid (ptid_t ptid)
- {
- pid_t pid;
- /* If we have an LWPID to work with, use it. Otherwise, we're
- dealing with a non-threaded program/target. */
- pid = ptid.lwp ();
- if (pid == 0)
- pid = ptid.pid ();
- return pid;
- }
- #endif
- /* Resume execution of thread PTID, or all threads if PTID is -1. If
- STEP is nonzero, single-step it. If SIGNAL is nonzero, give it
- that signal. */
- void
- inf_ptrace_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
- {
- PTRACE_TYPE_ARG1 request;
- if (minus_one_ptid == ptid)
- /* Resume all threads. Traditionally ptrace() only supports
- single-threaded processes, so simply resume the inferior. */
- ptid = ptid_t (inferior_ptid.pid ());
- if (catch_syscall_enabled () > 0)
- request = PT_SYSCALL;
- else
- request = PT_CONTINUE;
- if (step)
- {
- /* If this system does not support PT_STEP, a higher level
- function will have called the appropriate functions to transmute the
- step request into a continue request (by setting breakpoints on
- all possible successor instructions), so we don't have to
- worry about that here. */
- request = PT_STEP;
- }
- /* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
- where it was. If GDB wanted it to start some other way, we have
- already written a new program counter value to the child. */
- errno = 0;
- gdb_ptrace (request, ptid, (PTRACE_TYPE_ARG3)1, gdb_signal_to_host (signal));
- if (errno != 0)
- perror_with_name (("ptrace"));
- }
- /* Wait for the child specified by PTID to do something. Return the
- process ID of the child, or MINUS_ONE_PTID in case of error; store
- the status in *OURSTATUS. */
- ptid_t
- inf_ptrace_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
- target_wait_flags target_options)
- {
- pid_t pid;
- int options, status, save_errno;
- options = 0;
- if (target_options & TARGET_WNOHANG)
- options |= WNOHANG;
- do
- {
- set_sigint_trap ();
- do
- {
- pid = waitpid (ptid.pid (), &status, options);
- save_errno = errno;
- }
- while (pid == -1 && errno == EINTR);
- clear_sigint_trap ();
- if (pid == 0)
- {
- gdb_assert (target_options & TARGET_WNOHANG);
- ourstatus->set_ignore ();
- return minus_one_ptid;
- }
- if (pid == -1)
- {
- /* In async mode the SIGCHLD might have raced and triggered
- a check for an event that had already been reported. If
- the event was the exit of the only remaining child,
- waitpid() will fail with ECHILD. */
- if (ptid == minus_one_ptid && save_errno == ECHILD)
- {
- ourstatus->set_no_resumed ();
- return minus_one_ptid;
- }
- gdb_printf (gdb_stderr,
- _("Child process unexpectedly missing: %s.\n"),
- safe_strerror (save_errno));
- ourstatus->set_ignore ();
- return minus_one_ptid;
- }
- /* Ignore terminated detached child processes. */
- if (!WIFSTOPPED (status) && find_inferior_pid (this, pid) == nullptr)
- pid = -1;
- }
- while (pid == -1);
- *ourstatus = host_status_to_waitstatus (status);
- return ptid_t (pid);
- }
- /* Transfer data via ptrace into process PID's memory from WRITEBUF, or
- from process PID's memory into READBUF. Start at target address ADDR
- and transfer up to LEN bytes. Exactly one of READBUF and WRITEBUF must
- be non-null. Return the number of transferred bytes. */
- static ULONGEST
- inf_ptrace_peek_poke (ptid_t ptid, gdb_byte *readbuf,
- const gdb_byte *writebuf,
- ULONGEST addr, ULONGEST len)
- {
- ULONGEST n;
- unsigned int chunk;
- /* We transfer aligned words. Thus align ADDR down to a word
- boundary and determine how many bytes to skip at the
- beginning. */
- ULONGEST skip = addr & (sizeof (PTRACE_TYPE_RET) - 1);
- addr -= skip;
- for (n = 0;
- n < len;
- n += chunk, addr += sizeof (PTRACE_TYPE_RET), skip = 0)
- {
- /* Restrict to a chunk that fits in the current word. */
- chunk = std::min (sizeof (PTRACE_TYPE_RET) - skip, len - n);
- /* Use a union for type punning. */
- union
- {
- PTRACE_TYPE_RET word;
- gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
- } buf;
- /* Read the word, also when doing a partial word write. */
- if (readbuf != NULL || chunk < sizeof (PTRACE_TYPE_RET))
- {
- errno = 0;
- buf.word = gdb_ptrace (PT_READ_I, ptid,
- (PTRACE_TYPE_ARG3)(uintptr_t) addr, 0);
- if (errno != 0)
- break;
- if (readbuf != NULL)
- memcpy (readbuf + n, buf.byte + skip, chunk);
- }
- if (writebuf != NULL)
- {
- memcpy (buf.byte + skip, writebuf + n, chunk);
- errno = 0;
- gdb_ptrace (PT_WRITE_D, ptid, (PTRACE_TYPE_ARG3)(uintptr_t) addr,
- buf.word);
- if (errno != 0)
- {
- /* Using the appropriate one (I or D) is necessary for
- Gould NP1, at least. */
- errno = 0;
- gdb_ptrace (PT_WRITE_I, ptid, (PTRACE_TYPE_ARG3)(uintptr_t) addr,
- buf.word);
- if (errno != 0)
- break;
- }
- }
- }
- return n;
- }
- /* Implement the to_xfer_partial target_ops method. */
- enum target_xfer_status
- inf_ptrace_target::xfer_partial (enum target_object object,
- const char *annex, gdb_byte *readbuf,
- const gdb_byte *writebuf,
- ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
- {
- ptid_t ptid = inferior_ptid;
- switch (object)
- {
- case TARGET_OBJECT_MEMORY:
- #ifdef PT_IO
- /* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
- request that promises to be much more efficient in reading
- and writing data in the traced process's address space. */
- {
- struct ptrace_io_desc piod;
- /* NOTE: We assume that there are no distinct address spaces
- for instruction and data. However, on OpenBSD 3.9 and
- later, PIOD_WRITE_D doesn't allow changing memory that's
- mapped read-only. Since most code segments will be
- read-only, using PIOD_WRITE_D will prevent us from
- inserting breakpoints, so we use PIOD_WRITE_I instead. */
- piod.piod_op = writebuf ? PIOD_WRITE_I : PIOD_READ_D;
- piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
- piod.piod_offs = (void *) (long) offset;
- piod.piod_len = len;
- errno = 0;
- if (gdb_ptrace (PT_IO, ptid, (caddr_t)&piod, 0) == 0)
- {
- /* Return the actual number of bytes read or written. */
- *xfered_len = piod.piod_len;
- return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
- }
- /* If the PT_IO request is somehow not supported, fallback on
- using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
- to indicate failure. */
- if (errno != EINVAL)
- return TARGET_XFER_EOF;
- }
- #endif
- *xfered_len = inf_ptrace_peek_poke (ptid, readbuf, writebuf,
- offset, len);
- return *xfered_len != 0 ? TARGET_XFER_OK : TARGET_XFER_EOF;
- case TARGET_OBJECT_UNWIND_TABLE:
- return TARGET_XFER_E_IO;
- case TARGET_OBJECT_AUXV:
- #if defined (PT_IO) && defined (PIOD_READ_AUXV)
- /* OpenBSD 4.5 has a new PIOD_READ_AUXV operation for the PT_IO
- request that allows us to read the auxilliary vector. Other
- BSD's may follow if they feel the need to support PIE. */
- {
- struct ptrace_io_desc piod;
- if (writebuf)
- return TARGET_XFER_E_IO;
- piod.piod_op = PIOD_READ_AUXV;
- piod.piod_addr = readbuf;
- piod.piod_offs = (void *) (long) offset;
- piod.piod_len = len;
- errno = 0;
- if (gdb_ptrace (PT_IO, ptid, (caddr_t)&piod, 0) == 0)
- {
- /* Return the actual number of bytes read or written. */
- *xfered_len = piod.piod_len;
- return (piod.piod_len == 0) ? TARGET_XFER_EOF : TARGET_XFER_OK;
- }
- }
- #endif
- return TARGET_XFER_E_IO;
- case TARGET_OBJECT_WCOOKIE:
- return TARGET_XFER_E_IO;
- default:
- return TARGET_XFER_E_IO;
- }
- }
- /* Return non-zero if the thread specified by PTID is alive. */
- bool
- inf_ptrace_target::thread_alive (ptid_t ptid)
- {
- /* ??? Is kill the right way to do this? */
- return (::kill (ptid.pid (), 0) != -1);
- }
- /* Print status information about what we're accessing. */
- void
- inf_ptrace_target::files_info ()
- {
- struct inferior *inf = current_inferior ();
- gdb_printf (_("\tUsing the running image of %s %s.\n"),
- inf->attach_flag ? "attached" : "child",
- target_pid_to_str (inferior_ptid).c_str ());
- }
- std::string
- inf_ptrace_target::pid_to_str (ptid_t ptid)
- {
- return normal_pid_to_str (ptid);
- }
- /* Implement the "close" target method. */
- void
- inf_ptrace_target::close ()
- {
- /* Unregister from the event loop. */
- if (is_async_p ())
- async (0);
- inf_child_target::close ();
- }
|