#define LIBTHREAD_DB_SO "libthread_db.so.1"
#endif
+/* GNU/Linux libthread_db support.
+
+ libthread_db is a library, provided along with libpthread.so, which
+ exposes the internals of the thread library to a debugger. It
+ allows GDB to find existing threads, new threads as they are
+ created, thread IDs (usually, the result of pthread_self), and
+ thread-local variables.
+
+ The libthread_db interface originates on Solaris, where it is
+ both more powerful and more complicated. This implementation
+ only works for LinuxThreads and NPTL, the two glibc threading
+ libraries. It assumes that each thread is permanently assigned
+ to a single light-weight process (LWP).
+
+ libthread_db-specific information is stored in the "private" field
+ of struct thread_info. When the field is NULL we do not yet have
+ information about the new thread; this could be temporary (created,
+ but the thread library's data structures do not reflect it yet)
+ or permanent (created using clone instead of pthread_create).
+
+ Process IDs managed by linux-thread-db.c match those used by
+ linux-nat.c: a common PID for all processes, an LWP ID for each
+ thread, and no TID. We save the TID in private. Keeping it out
+ of the ptid_t prevents thread IDs changing when libpthread is
+ loaded or unloaded. */
+
/* If we're running on GNU/Linux, we must explicitly attach to any new
threads. */
static void thread_db_find_new_threads (void);
static void attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
const td_thrinfo_t *ti_p);
-static void detach_thread (ptid_t ptid, int verbose);
-\f
-
-/* Building process ids. */
-
-#define GET_PID(ptid) ptid_get_pid (ptid)
-#define GET_LWP(ptid) ptid_get_lwp (ptid)
-#define GET_THREAD(ptid) ptid_get_tid (ptid)
-
-#define is_lwp(ptid) (GET_LWP (ptid) != 0)
-#define is_thread(ptid) (GET_THREAD (ptid) != 0)
-
-#define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
+static void detach_thread (ptid_t ptid);
\f
/* Use "struct private_thread_info" to cache thread state. This is
unsigned int dying:1;
/* Cached thread state. */
- unsigned int th_valid:1;
- unsigned int ti_valid:1;
-
td_thrhandle_t th;
- td_thrinfo_t ti;
+ thread_t tid;
};
\f
thread_db_err_str (err));
/* Fill the cache. */
- thread_ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, ti.ti_tid);
+ thread_ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, 0);
thread_info = find_thread_pid (thread_ptid);
/* In the case of a zombie thread, don't continue. We don't want to
{
if (infop != NULL)
*(struct thread_info **) infop = thread_info;
- if (thread_info != NULL)
- {
- memcpy (&thread_info->private->th, thp, sizeof (*thp));
- thread_info->private->th_valid = 1;
- memcpy (&thread_info->private->ti, &ti, sizeof (ti));
- thread_info->private->ti_valid = 1;
- }
return TD_THR_ZOMBIE;
}
gdb_assert (thread_info != NULL);
}
- memcpy (&thread_info->private->th, thp, sizeof (*thp));
- thread_info->private->th_valid = 1;
- memcpy (&thread_info->private->ti, &ti, sizeof (ti));
- thread_info->private->ti_valid = 1;
-
if (infop != NULL)
*(struct thread_info **) infop = thread_info;
return 0;
}
-
-/* Accessor functions for the thread_db information, with caching. */
-
-static void
-thread_db_map_id2thr (struct thread_info *thread_info, int fatal)
-{
- td_err_e err;
-
- if (thread_info->private->th_valid)
- return;
-
- err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (thread_info->ptid),
- &thread_info->private->th);
- if (err != TD_OK)
- {
- if (fatal)
- error (_("Cannot find thread %ld: %s"),
- (long) GET_THREAD (thread_info->ptid),
- thread_db_err_str (err));
- }
- else
- thread_info->private->th_valid = 1;
-}
\f
/* Convert between user-level thread ids and LWP ids. */
struct thread_info *thread_info;
ptid_t thread_ptid;
- if (GET_LWP (ptid) == 0)
- ptid = BUILD_LWP (GET_PID (ptid), GET_PID (ptid));
-
- gdb_assert (is_lwp (ptid));
+ /* This ptid comes from linux-nat.c, which should always fill in the
+ LWP. */
+ gdb_assert (GET_LWP (ptid) != 0);
err = td_ta_map_lwp2thr_p (thread_agent, GET_LWP (ptid), &th);
if (err != TD_OK)
&& thread_info == NULL)
return pid_to_ptid (-1);
- gdb_assert (thread_info && thread_info->private->ti_valid);
-
- return ptid_build (GET_PID (ptid), GET_LWP (ptid),
- thread_info->private->ti.ti_tid);
-}
-
-static ptid_t
-lwp_from_thread (ptid_t ptid)
-{
- return BUILD_LWP (GET_LWP (ptid), GET_PID (ptid));
+ gdb_assert (ptid_get_tid (ptid) == 0);
+ return ptid;
}
\f
attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
const td_thrinfo_t *ti_p)
{
- struct thread_info *tp;
+ struct private_thread_info *private;
+ struct thread_info *tp = NULL;
td_err_e err;
/* If we're being called after a TD_CREATE event, we may already
tp = find_thread_pid (ptid);
gdb_assert (tp != NULL);
- if (!tp->private->dying)
- return;
+ /* If tp->private is NULL, then GDB is already attached to this
+ thread, but we do not know anything about it. We can learn
+ about it here. This can only happen if we have some other
+ way besides libthread_db to notice new threads (i.e.
+ PTRACE_EVENT_CLONE); assume the same mechanism notices thread
+ exit, so this can not be a stale thread recreated with the
+ same ID. */
+ if (tp->private != NULL)
+ {
+ if (!tp->private->dying)
+ return;
- delete_thread (ptid);
+ delete_thread (ptid);
+ tp = NULL;
+ }
}
check_thread_signals ();
return; /* A zombie thread -- do not attach. */
/* Under GNU/Linux, we have to attach to each and every thread. */
- if (lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
+ if (tp == NULL
+ && lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
return;
+ /* Construct the thread's private data. */
+ private = xmalloc (sizeof (struct private_thread_info));
+ memset (private, 0, sizeof (struct private_thread_info));
+
+ /* A thread ID of zero may mean the thread library has not initialized
+ yet. But we shouldn't even get here if that's the case. FIXME:
+ if we change GDB to always have at least one thread in the thread
+ list this will have to go somewhere else; maybe private == NULL
+ until the thread_db target claims it. */
+ gdb_assert (ti_p->ti_tid != 0);
+ private->th = *th_p;
+ private->tid = ti_p->ti_tid;
+
/* Add the thread to GDB's thread list. */
- tp = add_thread (ptid);
- tp->private = xmalloc (sizeof (struct private_thread_info));
- memset (tp->private, 0, sizeof (struct private_thread_info));
+ if (tp == NULL)
+ tp = add_thread_with_info (ptid, private);
+ else
+ tp->private = private;
/* Enable thread event reporting for this thread. */
err = td_thr_event_enable_p (th_p, 1);
}
static void
-detach_thread (ptid_t ptid, int verbose)
+detach_thread (ptid_t ptid)
{
struct thread_info *thread_info;
- if (verbose)
- printf_unfiltered (_("[%s exited]\n"), target_pid_to_str (ptid));
-
/* Don't delete the thread now, because it still reports as active
until it has executed a few instructions after the event
breakpoint - if we deleted it now, "info threads" would cause us
to re-attach to it. Just mark it as having had a TD_DEATH
event. This means that we won't delete it from our thread list
until we notice that it's dead (via prune_threads), or until
- something re-uses its thread ID. */
+ something re-uses its thread ID. We'll report the thread exit
+ when the underlying LWP dies. */
thread_info = find_thread_pid (ptid);
- gdb_assert (thread_info != NULL);
+ gdb_assert (thread_info != NULL && thread_info->private != NULL);
thread_info->private->dying = 1;
}
{
disable_thread_event_reporting ();
- /* There's no need to save & restore inferior_ptid here, since the
- inferior is not supposed to survive this function call. */
- inferior_ptid = lwp_from_thread (inferior_ptid);
-
target_beneath->to_detach (args, from_tty);
/* Should this be done by detach_command? */
target_mourn_inferior ();
}
-static int
-clear_lwpid_callback (struct thread_info *thread, void *dummy)
-{
- /* If we know that our thread implementation is 1-to-1, we could save
- a certain amount of information; it's not clear how much, so we
- are always conservative. */
-
- thread->private->th_valid = 0;
- thread->private->ti_valid = 0;
-
- return 0;
-}
-
-static void
-thread_db_resume (ptid_t ptid, int step, enum target_signal signo)
-{
- struct cleanup *old_chain = save_inferior_ptid ();
-
- if (GET_PID (ptid) == -1)
- inferior_ptid = lwp_from_thread (inferior_ptid);
- else if (is_thread (ptid))
- ptid = lwp_from_thread (ptid);
-
- /* Clear cached data which may not be valid after the resume. */
- iterate_over_threads (clear_lwpid_callback, NULL);
-
- target_beneath->to_resume (ptid, step, signo);
-
- do_cleanups (old_chain);
-}
-
/* Check if PID is currently stopped at the location of a thread event
breakpoint location. If it is, read the event message and act upon
the event. */
if (err != TD_OK)
error (_("Cannot get thread info: %s"), thread_db_err_str (err));
- ptid = ptid_build (GET_PID (ptid), ti.ti_lid, ti.ti_tid);
+ ptid = ptid_build (GET_PID (ptid), ti.ti_lid, 0);
switch (msg.event)
{
if (!in_thread_list (ptid))
error (_("Spurious thread death event."));
- detach_thread (ptid, print_thread_events);
+ detach_thread (ptid);
break;
{
extern ptid_t trap_ptid;
- if (GET_PID (ptid) != -1 && is_thread (ptid))
- ptid = lwp_from_thread (ptid);
-
ptid = target_beneath->to_wait (ptid, ourstatus);
if (ourstatus->kind == TARGET_WAITKIND_EXITED
return ptid;
}
-static void
-thread_db_kill (void)
-{
- /* There's no need to save & restore inferior_ptid here, since the
- inferior isn't supposed to survive this function call. */
- inferior_ptid = lwp_from_thread (inferior_ptid);
- target_beneath->to_kill ();
-}
-
static void
thread_db_mourn_inferior (void)
{
if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
return 0; /* A zombie -- ignore. */
- ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, ti.ti_tid);
+ ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, 0);
if (ti.ti_tid == 0)
{
static char *
thread_db_pid_to_str (ptid_t ptid)
{
- if (is_thread (ptid))
+ struct thread_info *thread_info = find_thread_pid (ptid);
+
+ if (thread_info != NULL && thread_info->private != NULL)
{
static char buf[64];
- struct thread_info *thread_info;
+ thread_t tid;
+ tid = thread_info->private->tid;
thread_info = find_thread_pid (ptid);
- if (thread_info == NULL)
- snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld) (Missing)",
- GET_THREAD (ptid), GET_LWP (ptid));
- else
- snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
- GET_THREAD (ptid), GET_LWP (ptid));
+ snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
+ tid, GET_LWP (ptid));
return buf;
}
static char *
thread_db_extra_thread_info (struct thread_info *info)
{
+ if (info->private == NULL)
+ return NULL;
+
if (info->private->dying)
return "Exiting";
return NULL;
}
-/* Return 1 if this thread has the same LWP as the passed PTID. */
-
-static int
-same_ptid_callback (struct thread_info *thread, void *arg)
-{
- ptid_t *ptid_p = arg;
-
- return GET_LWP (thread->ptid) == GET_LWP (*ptid_p);
-}
-
/* Get the address of the thread local variable in load module LM which
is stored at OFFSET within the thread local storage for thread PTID. */
CORE_ADDR lm,
CORE_ADDR offset)
{
+ struct thread_info *thread_info;
+
/* If we have not discovered any threads yet, check now. */
- if (!is_thread (ptid) && !have_threads ())
+ if (!have_threads ())
thread_db_find_new_threads ();
- /* Try to find a matching thread if we still have the LWP ID instead
- of the thread ID. */
- if (!is_thread (ptid))
- {
- struct thread_info *thread;
-
- thread = iterate_over_threads (same_ptid_callback, &ptid);
- if (thread != NULL)
- ptid = thread->ptid;
- }
+ /* Find the matching thread. */
+ thread_info = find_thread_pid (ptid);
- if (is_thread (ptid))
+ if (thread_info != NULL && thread_info->private != NULL)
{
td_err_e err;
void *address;
- struct thread_info *thread_info;
/* glibc doesn't provide the needed interface. */
if (!td_thr_tls_get_addr_p)
/* Caller should have verified that lm != 0. */
gdb_assert (lm != 0);
- /* Get info about the thread. */
- thread_info = find_thread_pid (ptid);
- gdb_assert (thread_info);
- thread_db_map_id2thr (thread_info, 1);
-
/* Finally, get the address of the variable. */
err = td_thr_tls_get_addr_p (&thread_info->private->th,
(void *)(size_t) lm,
thread_db_ops.to_longname = "multi-threaded child process.";
thread_db_ops.to_doc = "Threads and pthreads support.";
thread_db_ops.to_detach = thread_db_detach;
- thread_db_ops.to_resume = thread_db_resume;
thread_db_ops.to_wait = thread_db_wait;
- thread_db_ops.to_kill = thread_db_kill;
thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
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