/* Thread management interface, for the remote server for GDB.
- Copyright (C) 2002-2015 Free Software Foundation, Inc.
+ Copyright (C) 2002-2020 Free Software Foundation, Inc.
Contributed by MontaVista Software.
#include "linux-low.h"
-extern int debug_threads;
-
-static int thread_db_use_events;
-
+#include "debug.h"
#include "gdb_proc_service.h"
#include "nat/gdb_thread_db.h"
-#include "gdb_vecs.h"
+#include "gdbsupport/gdb_vecs.h"
#include "nat/linux-procfs.h"
+#include "gdbsupport/scoped_restore.h"
#ifndef USE_LIBTHREAD_DB_DIRECTLY
#include <dlfcn.h>
void *handle;
#endif
- /* Thread creation event breakpoint. The code at this location in
- the child process will be called by the pthread library whenever
- a new thread is created. By setting a special breakpoint at this
- location, GDB can detect when a new thread is created. We obtain
- this location via the td_ta_event_addr call. Note that if the
- running kernel supports tracing clones, then we don't need to use
- (and in fact don't use) this magic thread event breakpoint to
- learn about threads. */
- struct breakpoint *td_create_bp;
-
/* Addresses of libthread_db functions. */
td_ta_new_ftype *td_ta_new_p;
- td_ta_event_getmsg_ftype * td_ta_event_getmsg_p;
- td_ta_set_event_ftype *td_ta_set_event_p;
- td_ta_event_addr_ftype *td_ta_event_addr_p;
td_ta_map_lwp2thr_ftype *td_ta_map_lwp2thr_p;
td_thr_get_info_ftype *td_thr_get_info_p;
- td_thr_event_enable_ftype *td_thr_event_enable_p;
td_ta_thr_iter_ftype *td_ta_thr_iter_p;
td_thr_tls_get_addr_ftype *td_thr_tls_get_addr_p;
td_thr_tlsbase_ftype *td_thr_tlsbase_p;
}
#endif
-static int
-thread_db_create_event (CORE_ADDR where)
-{
- td_event_msg_t msg;
- td_err_e err;
- struct lwp_info *lwp;
- struct thread_db *thread_db = current_process ()->priv->thread_db;
-
- gdb_assert (thread_db->td_ta_event_getmsg_p != NULL);
-
- if (debug_threads)
- debug_printf ("Thread creation event.\n");
-
- /* FIXME: This assumes we don't get another event.
- In the LinuxThreads implementation, this is safe,
- because all events come from the manager thread
- (except for its own creation, of course). */
- err = thread_db->td_ta_event_getmsg_p (thread_db->thread_agent, &msg);
- if (err != TD_OK)
- fprintf (stderr, "thread getmsg err: %s\n",
- thread_db_err_str (err));
-
- /* If we do not know about the main thread yet, this would be a good time to
- find it. We need to do this to pick up the main thread before any newly
- created threads. */
- lwp = get_thread_lwp (current_thread);
- if (lwp->thread_known == 0)
- find_one_thread (current_thread->entry.id);
-
- /* msg.event == TD_EVENT_CREATE */
-
- find_new_threads_callback (msg.th_p, NULL);
-
- return 0;
-}
-
-static int
-thread_db_enable_reporting (void)
-{
- td_thr_events_t events;
- td_notify_t notify;
- td_err_e err;
- struct thread_db *thread_db = current_process ()->priv->thread_db;
-
- if (thread_db->td_ta_set_event_p == NULL
- || thread_db->td_ta_event_addr_p == NULL
- || thread_db->td_ta_event_getmsg_p == NULL)
- /* This libthread_db is missing required support. */
- return 0;
-
- /* Set the process wide mask saying which events we're interested in. */
- td_event_emptyset (&events);
- td_event_addset (&events, TD_CREATE);
-
- err = thread_db->td_ta_set_event_p (thread_db->thread_agent, &events);
- if (err != TD_OK)
- {
- warning ("Unable to set global thread event mask: %s",
- thread_db_err_str (err));
- return 0;
- }
-
- /* Get address for thread creation breakpoint. */
- err = thread_db->td_ta_event_addr_p (thread_db->thread_agent, TD_CREATE,
- ¬ify);
- if (err != TD_OK)
- {
- warning ("Unable to get location for thread creation breakpoint: %s",
- thread_db_err_str (err));
- return 0;
- }
- thread_db->td_create_bp
- = set_breakpoint_at ((CORE_ADDR) (unsigned long) notify.u.bptaddr,
- thread_db_create_event);
-
- return 1;
-}
+/* Get thread info about PTID, accessing memory via the current
+ thread. */
static int
find_one_thread (ptid_t ptid)
td_thrhandle_t th;
td_thrinfo_t ti;
td_err_e err;
- struct thread_info *inferior;
struct lwp_info *lwp;
struct thread_db *thread_db = current_process ()->priv->thread_db;
- int lwpid = ptid_get_lwp (ptid);
+ int lwpid = ptid.lwp ();
- inferior = (struct thread_info *) find_inferior_id (&all_threads, ptid);
- lwp = get_thread_lwp (inferior);
+ thread_info *thread = find_thread_ptid (ptid);
+ lwp = get_thread_lwp (thread);
if (lwp->thread_known)
return 1;
if (debug_threads)
debug_printf ("Found thread %ld (LWP %d)\n",
- ti.ti_tid, ti.ti_lid);
+ (unsigned long) ti.ti_tid, ti.ti_lid);
if (lwpid != ti.ti_lid)
{
return 0;
}
- if (thread_db_use_events)
- {
- err = thread_db->td_thr_event_enable_p (&th, 1);
- if (err != TD_OK)
- error ("Cannot enable thread event reporting for %d: %s",
- ti.ti_lid, thread_db_err_str (err));
- }
-
/* If the new thread ID is zero, a final thread ID will be available
later. Do not enable thread debugging yet. */
if (ti.ti_tid == 0)
lwp->thread_known = 1;
lwp->th = th;
+ lwp->thread_handle = ti.ti_tid;
return 1;
}
{
struct process_info *proc = current_process ();
int pid = pid_of (proc);
- ptid_t ptid = ptid_build (pid, ti_p->ti_lid, 0);
+ ptid_t ptid = ptid_t (pid, ti_p->ti_lid, 0);
struct lwp_info *lwp;
int err;
if (debug_threads)
debug_printf ("Attaching to thread %ld (LWP %d)\n",
- ti_p->ti_tid, ti_p->ti_lid);
+ (unsigned long) ti_p->ti_tid, ti_p->ti_lid);
err = linux_attach_lwp (ptid);
if (err != 0)
{
- warning ("Could not attach to thread %ld (LWP %d): %s\n",
- ti_p->ti_tid, ti_p->ti_lid,
- linux_ptrace_attach_fail_reason_string (ptid, err));
+ std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err);
+
+ warning ("Could not attach to thread %ld (LWP %d): %s",
+ (unsigned long) ti_p->ti_tid, ti_p->ti_lid, reason.c_str ());
+
return 0;
}
gdb_assert (lwp != NULL);
lwp->thread_known = 1;
lwp->th = *th_p;
-
- if (thread_db_use_events)
- {
- td_err_e err;
- struct thread_db *thread_db = proc->priv->thread_db;
-
- err = thread_db->td_thr_event_enable_p (th_p, 1);
- if (err != TD_OK)
- error ("Cannot enable thread event reporting for %d: %s",
- ti_p->ti_lid, thread_db_err_str (err));
- }
+ lwp->thread_handle = ti_p->ti_tid;
return 1;
}
{
struct lwp_info *lwp;
- lwp = find_lwp_pid (pid_to_ptid (ti_p->ti_lid));
+ lwp = find_lwp_pid (ptid_t (ti_p->ti_lid));
if (lwp != NULL)
return 1;
glibc PR17707. */
if (debug_threads)
debug_printf ("thread_db: skipping exited and "
- "joined thread (0x%lx)\n", ti.ti_tid);
+ "joined thread (0x%lx)\n",
+ (unsigned long) ti.ti_tid);
return 0;
}
lwp = get_thread_lwp (thread);
if (!lwp->thread_known)
- find_one_thread (thread->entry.id);
+ find_one_thread (thread->id);
if (!lwp->thread_known)
return TD_NOTHR;
return err;
}
+/* See linux-low.h. */
+
+bool
+thread_db_thread_handle (ptid_t ptid, gdb_byte **handle, int *handle_len)
+{
+ struct thread_db *thread_db;
+ struct lwp_info *lwp;
+ thread_info *thread = find_thread_ptid (ptid);
+
+ if (thread == NULL)
+ return false;
+
+ thread_db = get_thread_process (thread)->priv->thread_db;
+
+ if (thread_db == NULL)
+ return false;
+
+ lwp = get_thread_lwp (thread);
+
+ if (!lwp->thread_known && !find_one_thread (thread->id))
+ return false;
+
+ gdb_assert (lwp->thread_known);
+
+ *handle = (gdb_byte *) &lwp->thread_handle;
+ *handle_len = sizeof (lwp->thread_handle);
+ return true;
+}
+
#ifdef USE_LIBTHREAD_DB_DIRECTLY
static int
tdb->td_ta_thr_iter_p = &td_ta_thr_iter;
tdb->td_symbol_list_p = &td_symbol_list;
- /* This is required only when thread_db_use_events is on. */
- tdb->td_thr_event_enable_p = &td_thr_event_enable;
-
/* These are not essential. */
- tdb->td_ta_event_addr_p = &td_ta_event_addr;
- tdb->td_ta_set_event_p = &td_ta_set_event;
- tdb->td_ta_event_getmsg_p = &td_ta_event_getmsg;
tdb->td_thr_tls_get_addr_p = &td_thr_tls_get_addr;
tdb->td_thr_tlsbase_p = &td_thr_tlsbase;
CHK (1, TDB_DLSYM (tdb, td_ta_thr_iter));
CHK (1, TDB_DLSYM (tdb, td_symbol_list));
- /* This is required only when thread_db_use_events is on. */
- CHK (thread_db_use_events, TDB_DLSYM (tdb, td_thr_event_enable));
-
/* These are not essential. */
- CHK (0, TDB_DLSYM (tdb, td_ta_event_addr));
- CHK (0, TDB_DLSYM (tdb, td_ta_set_event));
- CHK (0, TDB_DLSYM (tdb, td_ta_event_getmsg));
CHK (0, TDB_DLSYM (tdb, td_thr_tls_get_addr));
CHK (0, TDB_DLSYM (tdb, td_thr_tlsbase));
const char *const libpath = dladdr_to_soname (td_init);
if (libpath != NULL)
- fprintf (stderr, "Host %s resolved to: %s.\n",
- library, libpath);
+ debug_printf ("Host %s resolved to: %s.\n", library, libpath);
}
}
#endif
static int
thread_db_load_search (void)
{
- VEC (char_ptr) *dir_vec;
- char *this_dir;
- int i, rc = 0;
+ int rc = 0;
if (libthread_db_search_path == NULL)
libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
- dir_vec = dirnames_to_char_ptr_vec (libthread_db_search_path);
+ std::vector<gdb::unique_xmalloc_ptr<char>> dir_vec
+ = dirnames_to_char_ptr_vec (libthread_db_search_path);
- for (i = 0; VEC_iterate (char_ptr, dir_vec, i, this_dir); ++i)
+ for (const gdb::unique_xmalloc_ptr<char> &this_dir_up : dir_vec)
{
+ char *this_dir = this_dir_up.get ();
const int pdir_len = sizeof ("$pdir") - 1;
size_t this_dir_len;
}
}
- free_char_ptr_vec (dir_vec);
if (debug_threads)
debug_printf ("thread_db_load_search returning %d\n", rc);
return rc;
#endif /* USE_LIBTHREAD_DB_DIRECTLY */
int
-thread_db_init (int use_events)
+thread_db_init (void)
{
struct process_info *proc = current_process ();
GNU/Linux calls tgid, "thread group ID". When we support
attaching to threads, the original thread may not be the correct
thread. We would have to get the process ID from /proc for NPTL.
- For LinuxThreads we could do something similar: follow the chain
- of parent processes until we find the highest one we're attached
- to, and use its tgid.
This isn't the only place in gdbserver that assumes that the first
process in the list is the thread group leader. */
- thread_db_use_events = use_events;
-
if (thread_db_load_search ())
{
- if (use_events && thread_db_enable_reporting () == 0)
- {
- /* Keep trying; maybe event reporting will work later. */
- thread_db_mourn (proc);
- return 0;
- }
-
/* It's best to avoid td_ta_thr_iter if possible. That walks
data structures in the inferior's address space that may be
corrupted, or, if the target is running, the list may change
while we walk it. In the latter case, it's possible that a
thread exits just at the exact time that causes GDBserver to
- get stuck in an infinite loop. If the kernel supports clone
- events, and /proc/PID/task/ exits, then we already know about
+ get stuck in an infinite loop. As the kernel supports clone
+ events and /proc/PID/task/ exists, then we already know about
all threads in the process. When we need info out of
thread_db on a given thread (e.g., for TLS), we'll use
find_one_thread then. That uses thread_db entry points that
do not walk libpthread's thread list, so should be safe, as
well as more efficient. */
- if (use_events
- || !linux_proc_task_list_dir_exists (pid_of (proc)))
+ if (!linux_proc_task_list_dir_exists (pid_of (proc)))
thread_db_find_new_threads ();
thread_db_look_up_symbols ();
return 1;
return 0;
}
-static int
-any_thread_of (struct inferior_list_entry *entry, void *args)
-{
- int *pid_p = (int *) args;
-
- if (ptid_get_pid (entry->id) == *pid_p)
- return 1;
-
- return 0;
-}
-
static void
switch_to_process (struct process_info *proc)
{
int pid = pid_of (proc);
- current_thread =
- (struct thread_info *) find_inferior (&all_threads,
- any_thread_of, &pid);
+ current_thread = find_any_thread_of_pid (pid);
}
/* Disconnect from libthread_db and free resources. */
}
}
-static void
-remove_thread_event_breakpoints (struct process_info *proc)
-{
- struct thread_db *thread_db = proc->priv->thread_db;
-
- if (thread_db->td_create_bp != NULL)
- {
- struct thread_info *saved_thread = current_thread;
-
- switch_to_process (proc);
-
- delete_breakpoint (thread_db->td_create_bp);
- thread_db->td_create_bp = NULL;
-
- current_thread = saved_thread;
- }
-}
-
void
thread_db_detach (struct process_info *proc)
{
if (thread_db)
{
disable_thread_event_reporting (proc);
- remove_thread_event_breakpoints (proc);
}
}
/* Tell server.c to perform default processing. */
return 0;
}
+
+/* See linux-low.h. */
+
+void
+thread_db_notice_clone (struct thread_info *parent_thr, ptid_t child_ptid)
+{
+ process_info *parent_proc = get_thread_process (parent_thr);
+ struct thread_db *thread_db = parent_proc->priv->thread_db;
+
+ /* If the thread layer isn't initialized, return. It may just
+ be that the program uses clone, but does not use libthread_db. */
+ if (thread_db == NULL || !thread_db->all_symbols_looked_up)
+ return;
+
+ /* find_one_thread calls into libthread_db which accesses memory via
+ the current thread. Temporarily switch to a thread we know is
+ stopped. */
+ scoped_restore restore_current_thread
+ = make_scoped_restore (¤t_thread, parent_thr);
+
+ if (!find_one_thread (child_ptid))
+ warning ("Cannot find thread after clone.");
+}
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