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old-cross-binutils/gdb/gdbserver/linux-low.c
Daniel Jacobowitz ae13219ef8 * inferiors.c (change_inferior_id): Add comment. 
* linux-low.c (check_removed_breakpoint): Add an early
	prototype.  Improve debug output.
	(linux_attach): Doc update.
	(linux_detach_one_process, linux_detach): Clean up before releasing
	each process.
	(send_sigstop, wait_for_sigstop): Improve comments and debug output.
	* linux-low.h (struct process_info): Doc improvement.
	* mem-break.c (delete_all_breakpoints): New.
	* mem-break.h (delete_all_breakpoints): New prototype.
	* thread-db.c (find_first_thread): New.
	(thread_db_create_event): Call it instead of
	thread_db_find_new_threads.  Clean up unused variables.
	(maybe_attach_thread): Remove first thread handling.
	(thread_db_find_new_threads): Use find_first_thread.
	(thread_db_get_tls_address): Likewise.
2007-07-02 15:35:36 +00:00

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/* Low level interface to ptrace, for the remote server for GDB.
Copyright (C) 1995, 1996, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007 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 2 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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA. */
#include "server.h"
#include "linux-low.h"
#include <sys/wait.h>
#include <stdio.h>
#include <sys/param.h>
#include <sys/dir.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/syscall.h>
#ifndef PTRACE_GETSIGINFO
# define PTRACE_GETSIGINFO 0x4202
# define PTRACE_SETSIGINFO 0x4203
#endif
#ifdef __UCLIBC__
#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
#define HAS_NOMMU
#endif
#endif
/* ``all_threads'' is keyed by the LWP ID - it should be the thread ID instead,
however. This requires changing the ID in place when we go from !using_threads
to using_threads, immediately.
``all_processes'' is keyed by the process ID - which on Linux is (presently)
the same as the LWP ID. */
struct inferior_list all_processes;
/* FIXME this is a bit of a hack, and could be removed. */
int stopping_threads;
/* FIXME make into a target method? */
int using_threads;
static void linux_resume_one_process (struct inferior_list_entry *entry,
int step, int signal, siginfo_t *info);
static void linux_resume (struct thread_resume *resume_info);
static void stop_all_processes (void);
static int linux_wait_for_event (struct thread_info *child);
static int check_removed_breakpoint (struct process_info *event_child);
struct pending_signals
{
int signal;
siginfo_t info;
struct pending_signals *prev;
};
#define PTRACE_ARG3_TYPE long
#define PTRACE_XFER_TYPE long
#ifdef HAVE_LINUX_REGSETS
static int use_regsets_p = 1;
#endif
#define pid_of(proc) ((proc)->head.id)
/* FIXME: Delete eventually. */
#define inferior_pid (pid_of (get_thread_process (current_inferior)))
/* This function should only be called if the process got a SIGTRAP.
The SIGTRAP could mean several things.
On i386, where decr_pc_after_break is non-zero:
If we were single-stepping this process using PTRACE_SINGLESTEP,
we will get only the one SIGTRAP (even if the instruction we
stepped over was a breakpoint). The value of $eip will be the
next instruction.
If we continue the process using PTRACE_CONT, we will get a
SIGTRAP when we hit a breakpoint. The value of $eip will be
the instruction after the breakpoint (i.e. needs to be
decremented). If we report the SIGTRAP to GDB, we must also
report the undecremented PC. If we cancel the SIGTRAP, we
must resume at the decremented PC.
(Presumably, not yet tested) On a non-decr_pc_after_break machine
with hardware or kernel single-step:
If we single-step over a breakpoint instruction, our PC will
point at the following instruction. If we continue and hit a
breakpoint instruction, our PC will point at the breakpoint
instruction. */
static CORE_ADDR
get_stop_pc (void)
{
CORE_ADDR stop_pc = (*the_low_target.get_pc) ();
if (get_thread_process (current_inferior)->stepping)
return stop_pc;
else
return stop_pc - the_low_target.decr_pc_after_break;
}
static void *
add_process (unsigned long pid)
{
struct process_info *process;
process = (struct process_info *) malloc (sizeof (*process));
memset (process, 0, sizeof (*process));
process->head.id = pid;
/* Default to tid == lwpid == pid. */
process->tid = pid;
process->lwpid = pid;
add_inferior_to_list (&all_processes, &process->head);
return process;
}
/* Start an inferior process and returns its pid.
ALLARGS is a vector of program-name and args. */
static int
linux_create_inferior (char *program, char **allargs)
{
void *new_process;
int pid;
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
pid = vfork ();
#else
pid = fork ();
#endif
if (pid < 0)
perror_with_name ("fork");
if (pid == 0)
{
ptrace (PTRACE_TRACEME, 0, 0, 0);
signal (__SIGRTMIN + 1, SIG_DFL);
setpgid (0, 0);
execv (program, allargs);
if (errno == ENOENT)
execvp (program, allargs);
fprintf (stderr, "Cannot exec %s: %s.\n", program,
strerror (errno));
fflush (stderr);
_exit (0177);
}
new_process = add_process (pid);
add_thread (pid, new_process, pid);
return pid;
}
/* Attach to an inferior process. */
void
linux_attach_lwp (unsigned long pid, unsigned long tid)
{
struct process_info *new_process;
if (ptrace (PTRACE_ATTACH, pid, 0, 0) != 0)
{
fprintf (stderr, "Cannot attach to process %ld: %s (%d)\n", pid,
strerror (errno), errno);
fflush (stderr);
/* If we fail to attach to an LWP, just return. */
if (!using_threads)
_exit (0177);
return;
}
new_process = (struct process_info *) add_process (pid);
add_thread (tid, new_process, pid);
/* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
brings it to a halt. We should ignore that SIGSTOP and resume the process
(unless this is the first process, in which case the flag will be cleared
in linux_attach).
On the other hand, if we are currently trying to stop all threads, we
should treat the new thread as if we had sent it a SIGSTOP. This works
because we are guaranteed that add_process added us to the end of the
list, and so the new thread has not yet reached wait_for_sigstop (but
will). */
if (! stopping_threads)
new_process->stop_expected = 1;
}
int
linux_attach (unsigned long pid)
{
struct process_info *process;
linux_attach_lwp (pid, pid);
/* Don't ignore the initial SIGSTOP if we just attached to this process.
It will be collected by wait shortly. */
process = (struct process_info *) find_inferior_id (&all_processes, pid);
process->stop_expected = 0;
return 0;
}
/* Kill the inferior process. Make us have no inferior. */
static void
linux_kill_one_process (struct inferior_list_entry *entry)
{
struct thread_info *thread = (struct thread_info *) entry;
struct process_info *process = get_thread_process (thread);
int wstat;
/* We avoid killing the first thread here, because of a Linux kernel (at
least 2.6.0-test7 through 2.6.8-rc4) bug; if we kill the parent before
the children get a chance to be reaped, it will remain a zombie
forever. */
if (entry == all_threads.head)
return;
do
{
ptrace (PTRACE_KILL, pid_of (process), 0, 0);
/* Make sure it died. The loop is most likely unnecessary. */
wstat = linux_wait_for_event (thread);
} while (WIFSTOPPED (wstat));
}
static void
linux_kill (void)
{
struct thread_info *thread = (struct thread_info *) all_threads.head;
struct process_info *process;
int wstat;
if (thread == NULL)
return;
for_each_inferior (&all_threads, linux_kill_one_process);
/* See the comment in linux_kill_one_process. We did not kill the first
thread in the list, so do so now. */
process = get_thread_process (thread);
do
{
ptrace (PTRACE_KILL, pid_of (process), 0, 0);
/* Make sure it died. The loop is most likely unnecessary. */
wstat = linux_wait_for_event (thread);
} while (WIFSTOPPED (wstat));
}
static void
linux_detach_one_process (struct inferior_list_entry *entry)
{
struct thread_info *thread = (struct thread_info *) entry;
struct process_info *process = get_thread_process (thread);
/* Make sure the process isn't stopped at a breakpoint that's
no longer there. */
check_removed_breakpoint (process);
/* If this process is stopped but is expecting a SIGSTOP, then make
sure we take care of that now. This isn't absolutely guaranteed
to collect the SIGSTOP, but is fairly likely to. */
if (process->stop_expected)
{
/* Clear stop_expected, so that the SIGSTOP will be reported. */
process->stop_expected = 0;
if (process->stopped)
linux_resume_one_process (&process->head, 0, 0, NULL);
linux_wait_for_event (thread);
}
/* Flush any pending changes to the process's registers. */
regcache_invalidate_one ((struct inferior_list_entry *)
get_process_thread (process));
/* Finally, let it resume. */
ptrace (PTRACE_DETACH, pid_of (process), 0, 0);
}
static int
linux_detach (void)
{
delete_all_breakpoints ();
for_each_inferior (&all_threads, linux_detach_one_process);
clear_inferiors ();
return 0;
}
static void
linux_join (void)
{
extern unsigned long signal_pid;
int status, ret;
do {
ret = waitpid (signal_pid, &status, 0);
if (WIFEXITED (status) || WIFSIGNALED (status))
break;
} while (ret != -1 || errno != ECHILD);
}
/* Return nonzero if the given thread is still alive. */
static int
linux_thread_alive (unsigned long tid)
{
if (find_inferior_id (&all_threads, tid) != NULL)
return 1;
else
return 0;
}
/* Return nonzero if this process stopped at a breakpoint which
no longer appears to be inserted. Also adjust the PC
appropriately to resume where the breakpoint used to be. */
static int
check_removed_breakpoint (struct process_info *event_child)
{
CORE_ADDR stop_pc;
struct thread_info *saved_inferior;
if (event_child->pending_is_breakpoint == 0)
return 0;
if (debug_threads)
fprintf (stderr, "Checking for breakpoint in process %ld.\n",
event_child->lwpid);
saved_inferior = current_inferior;
current_inferior = get_process_thread (event_child);
stop_pc = get_stop_pc ();
/* If the PC has changed since we stopped, then we shouldn't do
anything. This happens if, for instance, GDB handled the
decr_pc_after_break subtraction itself. */
if (stop_pc != event_child->pending_stop_pc)
{
if (debug_threads)
fprintf (stderr, "Ignoring, PC was changed. Old PC was 0x%08llx\n",
event_child->pending_stop_pc);
event_child->pending_is_breakpoint = 0;
current_inferior = saved_inferior;
return 0;
}
/* If the breakpoint is still there, we will report hitting it. */
if ((*the_low_target.breakpoint_at) (stop_pc))
{
if (debug_threads)
fprintf (stderr, "Ignoring, breakpoint is still present.\n");
current_inferior = saved_inferior;
return 0;
}
if (debug_threads)
fprintf (stderr, "Removed breakpoint.\n");
/* For decr_pc_after_break targets, here is where we perform the
decrement. We go immediately from this function to resuming,
and can not safely call get_stop_pc () again. */
if (the_low_target.set_pc != NULL)
(*the_low_target.set_pc) (stop_pc);
/* We consumed the pending SIGTRAP. */
event_child->pending_is_breakpoint = 0;
event_child->status_pending_p = 0;
event_child->status_pending = 0;
current_inferior = saved_inferior;
return 1;
}
/* Return 1 if this process has an interesting status pending. This function
may silently resume an inferior process. */
static int
status_pending_p (struct inferior_list_entry *entry, void *dummy)
{
struct process_info *process = (struct process_info *) entry;
if (process->status_pending_p)
if (check_removed_breakpoint (process))
{
/* This thread was stopped at a breakpoint, and the breakpoint
is now gone. We were told to continue (or step...) all threads,
so GDB isn't trying to single-step past this breakpoint.
So instead of reporting the old SIGTRAP, pretend we got to
the breakpoint just after it was removed instead of just
before; resume the process. */
linux_resume_one_process (&process->head, 0, 0, NULL);
return 0;
}
return process->status_pending_p;
}
static void
linux_wait_for_process (struct process_info **childp, int *wstatp)
{
int ret;
int to_wait_for = -1;
if (*childp != NULL)
to_wait_for = (*childp)->lwpid;
while (1)
{
ret = waitpid (to_wait_for, wstatp, WNOHANG);
if (ret == -1)
{
if (errno != ECHILD)
perror_with_name ("waitpid");
}
else if (ret > 0)
break;
ret = waitpid (to_wait_for, wstatp, WNOHANG | __WCLONE);
if (ret == -1)
{
if (errno != ECHILD)
perror_with_name ("waitpid (WCLONE)");
}
else if (ret > 0)
break;
usleep (1000);
}
if (debug_threads
&& (!WIFSTOPPED (*wstatp)
|| (WSTOPSIG (*wstatp) != 32
&& WSTOPSIG (*wstatp) != 33)))
fprintf (stderr, "Got an event from %d (%x)\n", ret, *wstatp);
if (to_wait_for == -1)
*childp = (struct process_info *) find_inferior_id (&all_processes, ret);
(*childp)->stopped = 1;
(*childp)->pending_is_breakpoint = 0;
(*childp)->last_status = *wstatp;
if (debug_threads
&& WIFSTOPPED (*wstatp))
{
current_inferior = (struct thread_info *)
find_inferior_id (&all_threads, (*childp)->tid);
/* For testing only; i386_stop_pc prints out a diagnostic. */
if (the_low_target.get_pc != NULL)
get_stop_pc ();
}
}
static int
linux_wait_for_event (struct thread_info *child)
{
CORE_ADDR stop_pc;
struct process_info *event_child;
int wstat;
/* Check for a process with a pending status. */
/* It is possible that the user changed the pending task's registers since
it stopped. We correctly handle the change of PC if we hit a breakpoint
(in check_removed_breakpoint); signals should be reported anyway. */
if (child == NULL)
{
event_child = (struct process_info *)
find_inferior (&all_processes, status_pending_p, NULL);
if (debug_threads && event_child)
fprintf (stderr, "Got a pending child %ld\n", event_child->lwpid);
}
else
{
event_child = get_thread_process (child);
if (event_child->status_pending_p
&& check_removed_breakpoint (event_child))
event_child = NULL;
}
if (event_child != NULL)
{
if (event_child->status_pending_p)
{
if (debug_threads)
fprintf (stderr, "Got an event from pending child %ld (%04x)\n",
event_child->lwpid, event_child->status_pending);
wstat = event_child->status_pending;
event_child->status_pending_p = 0;
event_child->status_pending = 0;
current_inferior = get_process_thread (event_child);
return wstat;
}
}
/* We only enter this loop if no process has a pending wait status. Thus
any action taken in response to a wait status inside this loop is
responding as soon as we detect the status, not after any pending
events. */
while (1)
{
if (child == NULL)
event_child = NULL;
else
event_child = get_thread_process (child);
linux_wait_for_process (&event_child, &wstat);
if (event_child == NULL)
error ("event from unknown child");
current_inferior = (struct thread_info *)
find_inferior_id (&all_threads, event_child->tid);
/* Check for thread exit. */
if (using_threads && ! WIFSTOPPED (wstat))
{
if (debug_threads)
fprintf (stderr, "Thread %ld (LWP %ld) exiting\n",
event_child->tid, event_child->head.id);
/* If the last thread is exiting, just return. */
if (all_threads.head == all_threads.tail)
return wstat;
dead_thread_notify (event_child->tid);
remove_inferior (&all_processes, &event_child->head);
free (event_child);
remove_thread (current_inferior);
current_inferior = (struct thread_info *) all_threads.head;
/* If we were waiting for this particular child to do something...
well, it did something. */
if (child != NULL)
return wstat;
/* Wait for a more interesting event. */
continue;
}
if (using_threads
&& WIFSTOPPED (wstat)
&& WSTOPSIG (wstat) == SIGSTOP
&& event_child->stop_expected)
{
if (debug_threads)
fprintf (stderr, "Expected stop.\n");
event_child->stop_expected = 0;
linux_resume_one_process (&event_child->head,
event_child->stepping, 0, NULL);
continue;
}
/* If GDB is not interested in this signal, don't stop other
threads, and don't report it to GDB. Just resume the
inferior right away. We do this for threading-related
signals as well as any that GDB specifically requested
we ignore. But never ignore SIGSTOP if we sent it
ourselves. */
/* FIXME drow/2002-06-09: Get signal numbers from the inferior's
thread library? */
if (WIFSTOPPED (wstat)
&& ((using_threads && (WSTOPSIG (wstat) == __SIGRTMIN
|| WSTOPSIG (wstat) == __SIGRTMIN + 1))
|| (pass_signals[target_signal_from_host (WSTOPSIG (wstat))]
&& (WSTOPSIG (wstat) != SIGSTOP
|| !event_child->sigstop_sent))))
{
siginfo_t info, *info_p;
if (debug_threads)
fprintf (stderr, "Ignored signal %d for %ld (LWP %ld).\n",
WSTOPSIG (wstat), event_child->tid,
event_child->head.id);
if (ptrace (PTRACE_GETSIGINFO, event_child->lwpid, 0, &info) == 0)
info_p = &info;
else
info_p = NULL;
linux_resume_one_process (&event_child->head,
event_child->stepping,
WSTOPSIG (wstat), info_p);
continue;
}
/* If this event was not handled above, and is not a SIGTRAP, report
it. */
if (!WIFSTOPPED (wstat) || WSTOPSIG (wstat) != SIGTRAP)
return wstat;
/* If this target does not support breakpoints, we simply report the
SIGTRAP; it's of no concern to us. */
if (the_low_target.get_pc == NULL)
return wstat;
stop_pc = get_stop_pc ();
/* bp_reinsert will only be set if we were single-stepping.
Notice that we will resume the process after hitting
a gdbserver breakpoint; single-stepping to/over one
is not supported (yet). */
if (event_child->bp_reinsert != 0)
{
if (debug_threads)
fprintf (stderr, "Reinserted breakpoint.\n");
reinsert_breakpoint (event_child->bp_reinsert);
event_child->bp_reinsert = 0;
/* Clear the single-stepping flag and SIGTRAP as we resume. */
linux_resume_one_process (&event_child->head, 0, 0, NULL);
continue;
}
if (debug_threads)
fprintf (stderr, "Hit a (non-reinsert) breakpoint.\n");
if (check_breakpoints (stop_pc) != 0)
{
/* We hit one of our own breakpoints. We mark it as a pending
breakpoint, so that check_removed_breakpoint () will do the PC
adjustment for us at the appropriate time. */
event_child->pending_is_breakpoint = 1;
event_child->pending_stop_pc = stop_pc;
/* Now we need to put the breakpoint back. We continue in the event
loop instead of simply replacing the breakpoint right away,
in order to not lose signals sent to the thread that hit the
breakpoint. Unfortunately this increases the window where another
thread could sneak past the removed breakpoint. For the current
use of server-side breakpoints (thread creation) this is
acceptable; but it needs to be considered before this breakpoint
mechanism can be used in more general ways. For some breakpoints
it may be necessary to stop all other threads, but that should
be avoided where possible.
If breakpoint_reinsert_addr is NULL, that means that we can
use PTRACE_SINGLESTEP on this platform. Uninsert the breakpoint,
mark it for reinsertion, and single-step.
Otherwise, call the target function to figure out where we need
our temporary breakpoint, create it, and continue executing this
process. */
if (the_low_target.breakpoint_reinsert_addr == NULL)
{
event_child->bp_reinsert = stop_pc;
uninsert_breakpoint (stop_pc);
linux_resume_one_process (&event_child->head, 1, 0, NULL);
}
else
{
reinsert_breakpoint_by_bp
(stop_pc, (*the_low_target.breakpoint_reinsert_addr) ());
linux_resume_one_process (&event_child->head, 0, 0, NULL);
}
continue;
}
/* If we were single-stepping, we definitely want to report the
SIGTRAP. The single-step operation has completed, so also
clear the stepping flag; in general this does not matter,
because the SIGTRAP will be reported to the client, which
will give us a new action for this thread, but clear it for
consistency anyway. It's safe to clear the stepping flag
because the only consumer of get_stop_pc () after this point
is check_removed_breakpoint, and pending_is_breakpoint is not
set. It might be wiser to use a step_completed flag instead. */
if (event_child->stepping)
{
event_child->stepping = 0;
return wstat;
}
/* A SIGTRAP that we can't explain. It may have been a breakpoint.
Check if it is a breakpoint, and if so mark the process information
accordingly. This will handle both the necessary fiddling with the
PC on decr_pc_after_break targets and suppressing extra threads
hitting a breakpoint if two hit it at once and then GDB removes it
after the first is reported. Arguably it would be better to report
multiple threads hitting breakpoints simultaneously, but the current
remote protocol does not allow this. */
if ((*the_low_target.breakpoint_at) (stop_pc))
{
event_child->pending_is_breakpoint = 1;
event_child->pending_stop_pc = stop_pc;
}
return wstat;
}
/* NOTREACHED */
return 0;
}
/* Wait for process, returns status. */
static unsigned char
linux_wait (char *status)
{
int w;
struct thread_info *child = NULL;
retry:
/* If we were only supposed to resume one thread, only wait for
that thread - if it's still alive. If it died, however - which
can happen if we're coming from the thread death case below -
then we need to make sure we restart the other threads. We could
pick a thread at random or restart all; restarting all is less
arbitrary. */
if (cont_thread != 0 && cont_thread != -1)
{
child = (struct thread_info *) find_inferior_id (&all_threads,
cont_thread);
/* No stepping, no signal - unless one is pending already, of course. */
if (child == NULL)
{
struct thread_resume resume_info;
resume_info.thread = -1;
resume_info.step = resume_info.sig = resume_info.leave_stopped = 0;
linux_resume (&resume_info);
}
}
enable_async_io ();
unblock_async_io ();
w = linux_wait_for_event (child);
stop_all_processes ();
disable_async_io ();
/* If we are waiting for a particular child, and it exited,
linux_wait_for_event will return its exit status. Similarly if
the last child exited. If this is not the last child, however,
do not report it as exited until there is a 'thread exited' response
available in the remote protocol. Instead, just wait for another event.
This should be safe, because if the thread crashed we will already
have reported the termination signal to GDB; that should stop any
in-progress stepping operations, etc.
Report the exit status of the last thread to exit. This matches
LinuxThreads' behavior. */
if (all_threads.head == all_threads.tail)
{
if (WIFEXITED (w))
{
fprintf (stderr, "\nChild exited with retcode = %x \n", WEXITSTATUS (w));
*status = 'W';
clear_inferiors ();
free (all_processes.head);
all_processes.head = all_processes.tail = NULL;
return WEXITSTATUS (w);
}
else if (!WIFSTOPPED (w))
{
fprintf (stderr, "\nChild terminated with signal = %x \n", WTERMSIG (w));
*status = 'X';
clear_inferiors ();
free (all_processes.head);
all_processes.head = all_processes.tail = NULL;
return target_signal_from_host (WTERMSIG (w));
}
}
else
{
if (!WIFSTOPPED (w))
goto retry;
}
*status = 'T';
return target_signal_from_host (WSTOPSIG (w));
}
/* Send a signal to an LWP. For LinuxThreads, kill is enough; however, if
thread groups are in use, we need to use tkill. */
static int
kill_lwp (unsigned long lwpid, int signo)
{
static int tkill_failed;
errno = 0;
#ifdef SYS_tkill
if (!tkill_failed)
{
int ret = syscall (SYS_tkill, lwpid, signo);
if (errno != ENOSYS)
return ret;
errno = 0;
tkill_failed = 1;
}
#endif
return kill (lwpid, signo);
}
static void
send_sigstop (struct inferior_list_entry *entry)
{
struct process_info *process = (struct process_info *) entry;
if (process->stopped)
return;
/* If we already have a pending stop signal for this process, don't
send another. */
if (process->stop_expected)
{
if (debug_threads)
fprintf (stderr, "Have pending sigstop for process %ld\n",
process->lwpid);
/* We clear the stop_expected flag so that wait_for_sigstop
will receive the SIGSTOP event (instead of silently resuming and
waiting again). It'll be reset below. */
process->stop_expected = 0;
return;
}
if (debug_threads)
fprintf (stderr, "Sending sigstop to process %ld\n", process->head.id);
kill_lwp (process->head.id, SIGSTOP);
process->sigstop_sent = 1;
}
static void
wait_for_sigstop (struct inferior_list_entry *entry)
{
struct process_info *process = (struct process_info *) entry;
struct thread_info *saved_inferior, *thread;
int wstat;
unsigned long saved_tid;
if (process->stopped)
return;
saved_inferior = current_inferior;
saved_tid = ((struct inferior_list_entry *) saved_inferior)->id;
thread = (struct thread_info *) find_inferior_id (&all_threads,
process->tid);
wstat = linux_wait_for_event (thread);
/* If we stopped with a non-SIGSTOP signal, save it for later
and record the pending SIGSTOP. If the process exited, just
return. */
if (WIFSTOPPED (wstat)
&& WSTOPSIG (wstat) != SIGSTOP)
{
if (debug_threads)
fprintf (stderr, "Process %ld (thread %ld) "
"stopped with non-sigstop status %06x\n",
process->lwpid, process->tid, wstat);
process->status_pending_p = 1;
process->status_pending = wstat;
process->stop_expected = 1;
}
if (linux_thread_alive (saved_tid))
current_inferior = saved_inferior;
else
{
if (debug_threads)
fprintf (stderr, "Previously current thread died.\n");
/* Set a valid thread as current. */
set_desired_inferior (0);
}
}
static void
stop_all_processes (void)
{
stopping_threads = 1;
for_each_inferior (&all_processes, send_sigstop);
for_each_inferior (&all_processes, wait_for_sigstop);
stopping_threads = 0;
}
/* Resume execution of the inferior process.
If STEP is nonzero, single-step it.
If SIGNAL is nonzero, give it that signal. */
static void
linux_resume_one_process (struct inferior_list_entry *entry,
int step, int signal, siginfo_t *info)
{
struct process_info *process = (struct process_info *) entry;
struct thread_info *saved_inferior;
if (process->stopped == 0)
return;
/* If we have pending signals or status, and a new signal, enqueue the
signal. Also enqueue the signal if we are waiting to reinsert a
breakpoint; it will be picked up again below. */
if (signal != 0
&& (process->status_pending_p || process->pending_signals != NULL
|| process->bp_reinsert != 0))
{
struct pending_signals *p_sig;
p_sig = malloc (sizeof (*p_sig));
p_sig->prev = process->pending_signals;
p_sig->signal = signal;
if (info == NULL)
memset (&p_sig->info, 0, sizeof (siginfo_t));
else
memcpy (&p_sig->info, info, sizeof (siginfo_t));
process->pending_signals = p_sig;
}
if (process->status_pending_p && !check_removed_breakpoint (process))
return;
saved_inferior = current_inferior;
current_inferior = get_process_thread (process);
if (debug_threads)
fprintf (stderr, "Resuming process %ld (%s, signal %d, stop %s)\n", inferior_pid,
step ? "step" : "continue", signal,
process->stop_expected ? "expected" : "not expected");
/* This bit needs some thinking about. If we get a signal that
we must report while a single-step reinsert is still pending,
we often end up resuming the thread. It might be better to
(ew) allow a stack of pending events; then we could be sure that
the reinsert happened right away and not lose any signals.
Making this stack would also shrink the window in which breakpoints are
uninserted (see comment in linux_wait_for_process) but not enough for
complete correctness, so it won't solve that problem. It may be
worthwhile just to solve this one, however. */
if (process->bp_reinsert != 0)
{
if (debug_threads)
fprintf (stderr, " pending reinsert at %08lx", (long)process->bp_reinsert);
if (step == 0)
fprintf (stderr, "BAD - reinserting but not stepping.\n");
step = 1;
/* Postpone any pending signal. It was enqueued above. */
signal = 0;
}
check_removed_breakpoint (process);
if (debug_threads && the_low_target.get_pc != NULL)
{
fprintf (stderr, " ");
(*the_low_target.get_pc) ();
}
/* If we have pending signals, consume one unless we are trying to reinsert
a breakpoint. */
if (process->pending_signals != NULL && process->bp_reinsert == 0)
{
struct pending_signals **p_sig;
p_sig = &process->pending_signals;
while ((*p_sig)->prev != NULL)
p_sig = &(*p_sig)->prev;
signal = (*p_sig)->signal;
if ((*p_sig)->info.si_signo != 0)
ptrace (PTRACE_SETSIGINFO, process->lwpid, 0, &(*p_sig)->info);
free (*p_sig);
*p_sig = NULL;
}
regcache_invalidate_one ((struct inferior_list_entry *)
get_process_thread (process));
errno = 0;
process->stopped = 0;
process->stepping = step;
ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, process->lwpid, 0, signal);
current_inferior = saved_inferior;
if (errno)
perror_with_name ("ptrace");
}
static struct thread_resume *resume_ptr;
/* This function is called once per thread. We look up the thread
in RESUME_PTR, and mark the thread with a pointer to the appropriate
resume request.
This algorithm is O(threads * resume elements), but resume elements
is small (and will remain small at least until GDB supports thread
suspension). */
static void
linux_set_resume_request (struct inferior_list_entry *entry)
{
struct process_info *process;
struct thread_info *thread;
int ndx;
thread = (struct thread_info *) entry;
process = get_thread_process (thread);
ndx = 0;
while (resume_ptr[ndx].thread != -1 && resume_ptr[ndx].thread != entry->id)
ndx++;
process->resume = &resume_ptr[ndx];
}
/* This function is called once per thread. We check the thread's resume
request, which will tell us whether to resume, step, or leave the thread
stopped; and what signal, if any, it should be sent. For threads which
we aren't explicitly told otherwise, we preserve the stepping flag; this
is used for stepping over gdbserver-placed breakpoints. */
static void
linux_continue_one_thread (struct inferior_list_entry *entry)
{
struct process_info *process;
struct thread_info *thread;
int step;
thread = (struct thread_info *) entry;
process = get_thread_process (thread);
if (process->resume->leave_stopped)
return;
if (process->resume->thread == -1)
step = process->stepping || process->resume->step;
else
step = process->resume->step;
linux_resume_one_process (&process->head, step, process->resume->sig, NULL);
process->resume = NULL;
}
/* This function is called once per thread. We check the thread's resume
request, which will tell us whether to resume, step, or leave the thread
stopped; and what signal, if any, it should be sent. We queue any needed
signals, since we won't actually resume. We already have a pending event
to report, so we don't need to preserve any step requests; they should
be re-issued if necessary. */
static void
linux_queue_one_thread (struct inferior_list_entry *entry)
{
struct process_info *process;
struct thread_info *thread;
thread = (struct thread_info *) entry;
process = get_thread_process (thread);
if (process->resume->leave_stopped)
return;
/* If we have a new signal, enqueue the signal. */
if (process->resume->sig != 0)
{
struct pending_signals *p_sig;
p_sig = malloc (sizeof (*p_sig));
p_sig->prev = process->pending_signals;
p_sig->signal = process->resume->sig;
memset (&p_sig->info, 0, sizeof (siginfo_t));
/* If this is the same signal we were previously stopped by,
make sure to queue its siginfo. We can ignore the return
value of ptrace; if it fails, we'll skip
PTRACE_SETSIGINFO. */
if (WIFSTOPPED (process->last_status)
&& WSTOPSIG (process->last_status) == process->resume->sig)
ptrace (PTRACE_GETSIGINFO, process->lwpid, 0, &p_sig->info);
process->pending_signals = p_sig;
}
process->resume = NULL;
}
/* Set DUMMY if this process has an interesting status pending. */
static int
resume_status_pending_p (struct inferior_list_entry *entry, void *flag_p)
{
struct process_info *process = (struct process_info *) entry;
/* Processes which will not be resumed are not interesting, because
we might not wait for them next time through linux_wait. */
if (process->resume->leave_stopped)
return 0;
/* If this thread has a removed breakpoint, we won't have any
events to report later, so check now. check_removed_breakpoint
may clear status_pending_p. We avoid calling check_removed_breakpoint
for any thread that we are not otherwise going to resume - this
lets us preserve stopped status when two threads hit a breakpoint.
GDB removes the breakpoint to single-step a particular thread
past it, then re-inserts it and resumes all threads. We want
to report the second thread without resuming it in the interim. */
if (process->status_pending_p)
check_removed_breakpoint (process);
if (process->status_pending_p)
* (int *) flag_p = 1;
return 0;
}
static void
linux_resume (struct thread_resume *resume_info)
{
int pending_flag;
/* Yes, the use of a global here is rather ugly. */
resume_ptr = resume_info;
for_each_inferior (&all_threads, linux_set_resume_request);
/* If there is a thread which would otherwise be resumed, which
has a pending status, then don't resume any threads - we can just
report the pending status. Make sure to queue any signals
that would otherwise be sent. */
pending_flag = 0;
find_inferior (&all_processes, resume_status_pending_p, &pending_flag);
if (debug_threads)
{
if (pending_flag)
fprintf (stderr, "Not resuming, pending status\n");
else
fprintf (stderr, "Resuming, no pending status\n");
}
if (pending_flag)
for_each_inferior (&all_threads, linux_queue_one_thread);
else
{
block_async_io ();
enable_async_io ();
for_each_inferior (&all_threads, linux_continue_one_thread);
}
}
#ifdef HAVE_LINUX_USRREGS
int
register_addr (int regnum)
{
int addr;
if (regnum < 0 || regnum >= the_low_target.num_regs)
error ("Invalid register number %d.", regnum);
addr = the_low_target.regmap[regnum];
return addr;
}
/* Fetch one register. */
static void
fetch_register (int regno)
{
CORE_ADDR regaddr;
int i, size;
char *buf;
if (regno >= the_low_target.num_regs)
return;
if ((*the_low_target.cannot_fetch_register) (regno))
return;
regaddr = register_addr (regno);
if (regaddr == -1)
return;
size = (register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
& - sizeof (PTRACE_XFER_TYPE);
buf = alloca (size);
for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
*(PTRACE_XFER_TYPE *) (buf + i) =
ptrace (PTRACE_PEEKUSER, inferior_pid, (PTRACE_ARG3_TYPE) regaddr, 0);
regaddr += sizeof (PTRACE_XFER_TYPE);
if (errno != 0)
{
/* Warning, not error, in case we are attached; sometimes the
kernel doesn't let us at the registers. */
char *err = strerror (errno);
char *msg = alloca (strlen (err) + 128);
sprintf (msg, "reading register %d: %s", regno, err);
error (msg);
goto error_exit;
}
}
if (the_low_target.left_pad_xfer
&& register_size (regno) < sizeof (PTRACE_XFER_TYPE))
supply_register (regno, (buf + sizeof (PTRACE_XFER_TYPE)
- register_size (regno)));
else
supply_register (regno, buf);
error_exit:;
}
/* Fetch all registers, or just one, from the child process. */
static void
usr_fetch_inferior_registers (int regno)
{
if (regno == -1 || regno == 0)
for (regno = 0; regno < the_low_target.num_regs; regno++)
fetch_register (regno);
else
fetch_register (regno);
}
/* Store our register values back into the inferior.
If REGNO is -1, do this for all registers.
Otherwise, REGNO specifies which register (so we can save time). */
static void
usr_store_inferior_registers (int regno)
{
CORE_ADDR regaddr;
int i, size;
char *buf;
if (regno >= 0)
{
if (regno >= the_low_target.num_regs)
return;
if ((*the_low_target.cannot_store_register) (regno) == 1)
return;
regaddr = register_addr (regno);
if (regaddr == -1)
return;
errno = 0;
size = (register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
& - sizeof (PTRACE_XFER_TYPE);
buf = alloca (size);
memset (buf, 0, size);
if (the_low_target.left_pad_xfer
&& register_size (regno) < sizeof (PTRACE_XFER_TYPE))
collect_register (regno, (buf + sizeof (PTRACE_XFER_TYPE)
- register_size (regno)));
else
collect_register (regno, buf);
for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
ptrace (PTRACE_POKEUSER, inferior_pid, (PTRACE_ARG3_TYPE) regaddr,
*(PTRACE_XFER_TYPE *) (buf + i));
if (errno != 0)
{
if ((*the_low_target.cannot_store_register) (regno) == 0)
{
char *err = strerror (errno);
char *msg = alloca (strlen (err) + 128);
sprintf (msg, "writing register %d: %s",
regno, err);
error (msg);
return;
}
}
regaddr += sizeof (PTRACE_XFER_TYPE);
}
}
else
for (regno = 0; regno < the_low_target.num_regs; regno++)
usr_store_inferior_registers (regno);
}
#endif /* HAVE_LINUX_USRREGS */
#ifdef HAVE_LINUX_REGSETS
static int
regsets_fetch_inferior_registers ()
{
struct regset_info *regset;
int saw_general_regs = 0;
regset = target_regsets;
while (regset->size >= 0)
{
void *buf;
int res;
if (regset->size == 0)
{
regset ++;
continue;
}
buf = malloc (regset->size);
res = ptrace (regset->get_request, inferior_pid, 0, buf);
if (res < 0)
{
if (errno == EIO)
{
/* If we get EIO on the first regset, do not try regsets again.
If we get EIO on a later regset, disable that regset. */
if (regset == target_regsets)
{
use_regsets_p = 0;
return -1;
}
else
{
regset->size = 0;
continue;
}
}
else
{
char s[256];
sprintf (s, "ptrace(regsets_fetch_inferior_registers) PID=%ld",
inferior_pid);
perror (s);
}
}
else if (regset->type == GENERAL_REGS)
saw_general_regs = 1;
regset->store_function (buf);
regset ++;
}
if (saw_general_regs)
return 0;
else
return 1;
}
static int
regsets_store_inferior_registers ()
{
struct regset_info *regset;
int saw_general_regs = 0;
regset = target_regsets;
while (regset->size >= 0)
{
void *buf;
int res;
if (regset->size == 0)
{
regset ++;
continue;
}
buf = malloc (regset->size);
/* First fill the buffer with the current register set contents,
in case there are any items in the kernel's regset that are
not in gdbserver's regcache. */
res = ptrace (regset->get_request, inferior_pid, 0, buf);
if (res == 0)
{
/* Then overlay our cached registers on that. */
regset->fill_function (buf);
/* Only now do we write the register set. */
res = ptrace (regset->set_request, inferior_pid, 0, buf);
}
if (res < 0)
{
if (errno == EIO)
{
/* If we get EIO on the first regset, do not try regsets again.
If we get EIO on a later regset, disable that regset. */
if (regset == target_regsets)
{
use_regsets_p = 0;
return -1;
}
else
{
regset->size = 0;
continue;
}
}
else
{
perror ("Warning: ptrace(regsets_store_inferior_registers)");
}
}
else if (regset->type == GENERAL_REGS)
saw_general_regs = 1;
regset ++;
free (buf);
}
if (saw_general_regs)
return 0;
else
return 1;
return 0;
}
#endif /* HAVE_LINUX_REGSETS */
void
linux_fetch_registers (int regno)
{
#ifdef HAVE_LINUX_REGSETS
if (use_regsets_p)
{
if (regsets_fetch_inferior_registers () == 0)
return;
}
#endif
#ifdef HAVE_LINUX_USRREGS
usr_fetch_inferior_registers (regno);
#endif
}
void
linux_store_registers (int regno)
{
#ifdef HAVE_LINUX_REGSETS
if (use_regsets_p)
{
if (regsets_store_inferior_registers () == 0)
return;
}
#endif
#ifdef HAVE_LINUX_USRREGS
usr_store_inferior_registers (regno);
#endif
}
/* Copy LEN bytes from inferior's memory starting at MEMADDR
to debugger memory starting at MYADDR. */
static int
linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
register int i;
/* Round starting address down to longword boundary. */
register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
/* Round ending address up; get number of longwords that makes. */
register int count
= (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
/ sizeof (PTRACE_XFER_TYPE);
/* Allocate buffer of that many longwords. */
register PTRACE_XFER_TYPE *buffer
= (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
/* Read all the longwords */
for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
buffer[i] = ptrace (PTRACE_PEEKTEXT, inferior_pid, (PTRACE_ARG3_TYPE) addr, 0);
if (errno)
return errno;
}
/* Copy appropriate bytes out of the buffer. */
memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), len);
return 0;
}
/* Copy LEN bytes of data from debugger memory at MYADDR
to inferior's memory at MEMADDR.
On failure (cannot write the inferior)
returns the value of errno. */
static int
linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
{
register int i;
/* Round starting address down to longword boundary. */
register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
/* Round ending address up; get number of longwords that makes. */
register int count
= (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1) / sizeof (PTRACE_XFER_TYPE);
/* Allocate buffer of that many longwords. */
register PTRACE_XFER_TYPE *buffer = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
extern int errno;
if (debug_threads)
{
fprintf (stderr, "Writing %02x to %08lx\n", (unsigned)myaddr[0], (long)memaddr);
}
/* Fill start and end extra bytes of buffer with existing memory data. */
buffer[0] = ptrace (PTRACE_PEEKTEXT, inferior_pid,
(PTRACE_ARG3_TYPE) addr, 0);
if (count > 1)
{
buffer[count - 1]
= ptrace (PTRACE_PEEKTEXT, inferior_pid,
(PTRACE_ARG3_TYPE) (addr + (count - 1)
* sizeof (PTRACE_XFER_TYPE)),
0);
}
/* Copy data to be written over corresponding part of buffer */
memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), myaddr, len);
/* Write the entire buffer. */
for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
ptrace (PTRACE_POKETEXT, inferior_pid, (PTRACE_ARG3_TYPE) addr, buffer[i]);
if (errno)
return errno;
}
return 0;
}
static void
linux_look_up_symbols (void)
{
#ifdef USE_THREAD_DB
if (using_threads)
return;
using_threads = thread_db_init ();
#endif
}
static void
linux_request_interrupt (void)
{
extern unsigned long signal_pid;
if (cont_thread != 0 && cont_thread != -1)
{
struct process_info *process;
process = get_thread_process (current_inferior);
kill_lwp (process->lwpid, SIGINT);
}
else
kill_lwp (signal_pid, SIGINT);
}
/* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET
to debugger memory starting at MYADDR. */
static int
linux_read_auxv (CORE_ADDR offset, unsigned char *myaddr, unsigned int len)
{
char filename[PATH_MAX];
int fd, n;
snprintf (filename, sizeof filename, "/proc/%ld/auxv", inferior_pid);
fd = open (filename, O_RDONLY);
if (fd < 0)
return -1;
if (offset != (CORE_ADDR) 0
&& lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
n = -1;
else
n = read (fd, myaddr, len);
close (fd);
return n;
}
/* These watchpoint related wrapper functions simply pass on the function call
if the target has registered a corresponding function. */
static int
linux_insert_watchpoint (char type, CORE_ADDR addr, int len)
{
if (the_low_target.insert_watchpoint != NULL)
return the_low_target.insert_watchpoint (type, addr, len);
else
/* Unsupported (see target.h). */
return 1;
}
static int
linux_remove_watchpoint (char type, CORE_ADDR addr, int len)
{
if (the_low_target.remove_watchpoint != NULL)
return the_low_target.remove_watchpoint (type, addr, len);
else
/* Unsupported (see target.h). */
return 1;
}
static int
linux_stopped_by_watchpoint (void)
{
if (the_low_target.stopped_by_watchpoint != NULL)
return the_low_target.stopped_by_watchpoint ();
else
return 0;
}
static CORE_ADDR
linux_stopped_data_address (void)
{
if (the_low_target.stopped_data_address != NULL)
return the_low_target.stopped_data_address ();
else
return 0;
}
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
#if defined(__mcoldfire__)
/* These should really be defined in the kernel's ptrace.h header. */
#define PT_TEXT_ADDR 49*4
#define PT_DATA_ADDR 50*4
#define PT_TEXT_END_ADDR 51*4
#endif
/* Under uClinux, programs are loaded at non-zero offsets, which we need
to tell gdb about. */
static int
linux_read_offsets (CORE_ADDR *text_p, CORE_ADDR *data_p)
{
#if defined(PT_TEXT_ADDR) && defined(PT_DATA_ADDR) && defined(PT_TEXT_END_ADDR)
unsigned long text, text_end, data;
int pid = get_thread_process (current_inferior)->head.id;
errno = 0;
text = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_ADDR, 0);
text_end = ptrace (PTRACE_PEEKUSER, pid, (long)PT_TEXT_END_ADDR, 0);
data = ptrace (PTRACE_PEEKUSER, pid, (long)PT_DATA_ADDR, 0);
if (errno == 0)
{
/* Both text and data offsets produced at compile-time (and so
used by gdb) are relative to the beginning of the program,
with the data segment immediately following the text segment.
However, the actual runtime layout in memory may put the data
somewhere else, so when we send gdb a data base-address, we
use the real data base address and subtract the compile-time
data base-address from it (which is just the length of the
text segment). BSS immediately follows data in both
cases. */
*text_p = text;
*data_p = data - (text_end - text);
return 1;
}
#endif
return 0;
}
#endif
static const char *
linux_arch_string (void)
{
return the_low_target.arch_string;
}
static struct target_ops linux_target_ops = {
linux_create_inferior,
linux_attach,
linux_kill,
linux_detach,
linux_join,
linux_thread_alive,
linux_resume,
linux_wait,
linux_fetch_registers,
linux_store_registers,
linux_read_memory,
linux_write_memory,
linux_look_up_symbols,
linux_request_interrupt,
linux_read_auxv,
linux_insert_watchpoint,
linux_remove_watchpoint,
linux_stopped_by_watchpoint,
linux_stopped_data_address,
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
linux_read_offsets,
#else
NULL,
#endif
#ifdef USE_THREAD_DB
thread_db_get_tls_address,
#else
NULL,
#endif
linux_arch_string,
};
static void
linux_init_signals ()
{
/* FIXME drow/2002-06-09: As above, we should check with LinuxThreads
to find what the cancel signal actually is. */
signal (__SIGRTMIN+1, SIG_IGN);
}
void
initialize_low (void)
{
using_threads = 0;
set_target_ops (&linux_target_ops);
set_breakpoint_data (the_low_target.breakpoint,
the_low_target.breakpoint_len);
init_registers ();
linux_init_signals ();
}
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