/* Thread management interface, for the remote server for GDB.
- Copyright (C) 2002, 2004, 2005, 2006
- Free Software Foundation, Inc.
+ Copyright (C) 2002-2020 Free Software Foundation, Inc.
Contributed by MontaVista Software.
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
+ 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,
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. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "server.h"
#include "linux-low.h"
-extern int debug_threads;
+#include "debug.h"
+#include "gdb_proc_service.h"
+#include "nat/gdb_thread_db.h"
+#include "gdbsupport/gdb_vecs.h"
+#include "nat/linux-procfs.h"
+#include "gdbsupport/scoped_restore.h"
-#ifdef HAVE_THREAD_DB_H
-#include <thread_db.h>
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+#include <dlfcn.h>
#endif
+#include <limits.h>
+#include <ctype.h>
-#include "gdb_proc_service.h"
+struct thread_db
+{
+ /* Structure that identifies the child process for the
+ <proc_service.h> interface. */
+ struct ps_prochandle proc_handle;
-/* Structure that identifies the child process for the
- <proc_service.h> interface. */
-static struct ps_prochandle proc_handle;
+ /* Connection to the libthread_db library. */
+ td_thragent_t *thread_agent;
-/* Connection to the libthread_db library. */
-static td_thragent_t *thread_agent;
+ /* If this flag has been set, we've already asked GDB for all
+ symbols we might need; assume symbol cache misses are
+ failures. */
+ int all_symbols_looked_up;
+
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+ /* Handle of the libthread_db from dlopen. */
+ void *handle;
+#endif
+ /* Addresses of libthread_db functions. */
+ td_ta_new_ftype *td_ta_new_p;
+ td_ta_map_lwp2thr_ftype *td_ta_map_lwp2thr_p;
+ td_thr_get_info_ftype *td_thr_get_info_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;
+ td_symbol_list_ftype *td_symbol_list_p;
+};
+
+static char *libthread_db_search_path;
+
+static int find_one_thread (ptid_t);
static int find_new_threads_callback (const td_thrhandle_t *th_p, void *data);
-static char *
+static const char *
thread_db_err_str (td_err_e err)
{
static char buf[64];
return "version mismatch between libthread_db and libpthread";
#endif
default:
- snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
+ xsnprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
return buf;
}
}
case TD_THR_STOPPED_ASLEEP:
return "stopped by debugger AND blocked";
default:
- snprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
+ xsnprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
return buf;
}
}
#endif
-static void
-thread_db_create_event (CORE_ADDR where)
+/* Get thread info about PTID, accessing memory via the current
+ thread. */
+
+static int
+find_one_thread (ptid_t ptid)
{
- td_event_msg_t msg;
+ td_thrhandle_t th;
+ td_thrinfo_t ti;
td_err_e err;
- struct inferior_linux_data *tdata;
+ struct lwp_info *lwp;
+ struct thread_db *thread_db = current_process ()->priv->thread_db;
+ int lwpid = ptid.lwp ();
- if (debug_threads)
- fprintf (stderr, "Thread creation event.\n");
+ thread_info *thread = find_thread_ptid (ptid);
+ lwp = get_thread_lwp (thread);
+ if (lwp->thread_known)
+ return 1;
- tdata = inferior_target_data (current_inferior);
+ /* Get information about this thread. */
+ err = thread_db->td_ta_map_lwp2thr_p (thread_db->thread_agent, lwpid, &th);
+ if (err != TD_OK)
+ error ("Cannot get thread handle for LWP %d: %s",
+ lwpid, thread_db_err_str (err));
- /* 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 = td_ta_event_getmsg (thread_agent, &msg);
+ err = thread_db->td_thr_get_info_p (&th, &ti);
if (err != TD_OK)
- fprintf (stderr, "thread getmsg err: %s\n",
- thread_db_err_str (err));
+ error ("Cannot get thread info for LWP %d: %s",
+ lwpid, thread_db_err_str (err));
- /* msg.event == TD_EVENT_CREATE */
+ if (debug_threads)
+ debug_printf ("Found thread %ld (LWP %d)\n",
+ (unsigned long) ti.ti_tid, ti.ti_lid);
- find_new_threads_callback (msg.th_p, NULL);
-}
+ if (lwpid != ti.ti_lid)
+ {
+ warning ("PID mismatch! Expected %ld, got %ld",
+ (long) lwpid, (long) ti.ti_lid);
+ return 0;
+ }
-#if 0
-static void
-thread_db_death_event (CORE_ADDR where)
-{
- if (debug_threads)
- fprintf (stderr, "Thread death event.\n");
+ /* 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)
+ return 0;
+
+ lwp->thread_known = 1;
+ lwp->th = th;
+ lwp->thread_handle = ti.ti_tid;
+
+ return 1;
}
-#endif
+
+/* Attach a thread. Return true on success. */
static int
-thread_db_enable_reporting ()
+attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
{
- td_thr_events_t events;
- td_notify_t notify;
- td_err_e err;
-
- /* Set the process wide mask saying which events we're interested in. */
- td_event_emptyset (&events);
- td_event_addset (&events, TD_CREATE);
-
-#if 0
- /* This is reported to be broken in glibc 2.1.3. A different approach
- will be necessary to support that. */
- td_event_addset (&events, TD_DEATH);
-#endif
+ struct process_info *proc = current_process ();
+ int pid = pid_of (proc);
+ ptid_t ptid = ptid_t (pid, ti_p->ti_lid, 0);
+ struct lwp_info *lwp;
+ int err;
- err = td_ta_set_event (thread_agent, &events);
- if (err != TD_OK)
+ if (debug_threads)
+ debug_printf ("Attaching to thread %ld (LWP %d)\n",
+ (unsigned long) ti_p->ti_tid, ti_p->ti_lid);
+ err = linux_attach_lwp (ptid);
+ if (err != 0)
{
- warning ("Unable to set global thread event mask: %s",
- thread_db_err_str (err));
- return 0;
- }
+ 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 ());
- /* Get address for thread creation breakpoint. */
- err = td_ta_event_addr (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;
}
- set_breakpoint_at ((CORE_ADDR) (unsigned long) notify.u.bptaddr,
- thread_db_create_event);
-#if 0
- /* Don't concern ourselves with reported thread deaths, only
- with actual thread deaths (via wait). */
-
- /* Get address for thread death breakpoint. */
- err = td_ta_event_addr (thread_agent, TD_DEATH, ¬ify);
- if (err != TD_OK)
- {
- warning ("Unable to get location for thread death breakpoint: %s",
- thread_db_err_str (err));
- return;
- }
- set_breakpoint_at ((CORE_ADDR) (unsigned long) notify.u.bptaddr,
- thread_db_death_event);
-#endif
+ lwp = find_lwp_pid (ptid);
+ gdb_assert (lwp != NULL);
+ lwp->thread_known = 1;
+ lwp->th = *th_p;
+ lwp->thread_handle = ti_p->ti_tid;
return 1;
}
-static void
-maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
-{
- td_err_e err;
- struct thread_info *inferior;
- struct process_info *process;
-
- /* If we are attaching to our first thread, things are a little
- different. */
- if (all_threads.head == all_threads.tail)
- {
- inferior = (struct thread_info *) all_threads.head;
- process = get_thread_process (inferior);
- if (process->thread_known == 0)
- {
- /* Switch to indexing the threads list by TID. */
- change_inferior_id (&all_threads, ti_p->ti_tid);
- goto found;
- }
- }
-
- inferior = (struct thread_info *) find_inferior_id (&all_threads,
- ti_p->ti_tid);
- if (inferior != NULL)
- return;
+/* Attach thread if we haven't seen it yet.
+ Increment *COUNTER if we have attached a new thread.
+ Return false on failure. */
- if (debug_threads)
- fprintf (stderr, "Attaching to thread %ld (LWP %d)\n",
- ti_p->ti_tid, ti_p->ti_lid);
- linux_attach_lwp (ti_p->ti_lid, ti_p->ti_tid);
- inferior = (struct thread_info *) find_inferior_id (&all_threads,
- ti_p->ti_tid);
- if (inferior == NULL)
- {
- warning ("Could not attach to thread %ld (LWP %d)\n",
- ti_p->ti_tid, ti_p->ti_lid);
- return;
- }
+static int
+maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p,
+ int *counter)
+{
+ struct lwp_info *lwp;
- process = inferior_target_data (inferior);
+ lwp = find_lwp_pid (ptid_t (ti_p->ti_lid));
+ if (lwp != NULL)
+ return 1;
-found:
- new_thread_notify (ti_p->ti_tid);
+ if (!attach_thread (th_p, ti_p))
+ return 0;
- process->tid = ti_p->ti_tid;
- process->lwpid = ti_p->ti_lid;
+ if (counter != NULL)
+ *counter += 1;
- process->thread_known = 1;
- err = td_thr_event_enable (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));
+ return 1;
}
static int
{
td_thrinfo_t ti;
td_err_e err;
+ struct thread_db *thread_db = current_process ()->priv->thread_db;
- err = td_thr_get_info (th_p, &ti);
+ err = thread_db->td_thr_get_info_p (th_p, &ti);
if (err != TD_OK)
error ("Cannot get thread info: %s", thread_db_err_str (err));
+ if (ti.ti_lid == -1)
+ {
+ /* A thread with kernel thread ID -1 is either a thread that
+ exited and was joined, or a thread that is being created but
+ hasn't started yet, and that is reusing the tcb/stack of a
+ thread that previously exited and was joined. (glibc marks
+ terminated and joined threads with kernel thread ID -1. See
+ glibc PR17707. */
+ if (debug_threads)
+ debug_printf ("thread_db: skipping exited and "
+ "joined thread (0x%lx)\n",
+ (unsigned long) ti.ti_tid);
+ return 0;
+ }
+
/* Check for zombies. */
if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
return 0;
- maybe_attach_thread (th_p, &ti);
+ if (!maybe_attach_thread (th_p, &ti, (int *) data))
+ {
+ /* Terminate iteration early: we might be looking at stale data in
+ the inferior. The thread_db_find_new_threads will retry. */
+ return 1;
+ }
return 0;
}
thread_db_find_new_threads (void)
{
td_err_e err;
+ ptid_t ptid = current_ptid;
+ struct thread_db *thread_db = current_process ()->priv->thread_db;
+ int loop, iteration;
+
+ /* This function is only called when we first initialize thread_db.
+ First locate the initial thread. If it is not ready for
+ debugging yet, then stop. */
+ if (find_one_thread (ptid) == 0)
+ return;
- /* Iterate over all user-space threads to discover new threads. */
- err = td_ta_thr_iter (thread_agent, find_new_threads_callback, NULL,
- TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
- TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+ /* Require 4 successive iterations which do not find any new threads.
+ The 4 is a heuristic: there is an inherent race here, and I have
+ seen that 2 iterations in a row are not always sufficient to
+ "capture" all threads. */
+ for (loop = 0, iteration = 0; loop < 4; ++loop, ++iteration)
+ {
+ int new_thread_count = 0;
+
+ /* Iterate over all user-space threads to discover new threads. */
+ err = thread_db->td_ta_thr_iter_p (thread_db->thread_agent,
+ find_new_threads_callback,
+ &new_thread_count,
+ TD_THR_ANY_STATE,
+ TD_THR_LOWEST_PRIORITY,
+ TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+ if (debug_threads)
+ debug_printf ("Found %d threads in iteration %d.\n",
+ new_thread_count, iteration);
+
+ if (new_thread_count != 0)
+ {
+ /* Found new threads. Restart iteration from beginning. */
+ loop = -1;
+ }
+ }
if (err != TD_OK)
error ("Cannot find new threads: %s", thread_db_err_str (err));
}
static void
thread_db_look_up_symbols (void)
{
- const char **sym_list = td_symbol_list ();
+ struct thread_db *thread_db = current_process ()->priv->thread_db;
+ const char **sym_list;
CORE_ADDR unused;
- for (sym_list = td_symbol_list (); *sym_list; sym_list++)
- look_up_one_symbol (*sym_list, &unused);
+ for (sym_list = thread_db->td_symbol_list_p (); *sym_list; sym_list++)
+ look_up_one_symbol (*sym_list, &unused, 1);
+
+ /* We're not interested in any other libraries loaded after this
+ point, only in symbols in libpthread.so. */
+ thread_db->all_symbols_looked_up = 1;
}
int
-thread_db_init ()
+thread_db_look_up_one_symbol (const char *name, CORE_ADDR *addrp)
{
- int err;
+ struct thread_db *thread_db = current_process ()->priv->thread_db;
+ int may_ask_gdb = !thread_db->all_symbols_looked_up;
+
+ /* If we've passed the call to thread_db_look_up_symbols, then
+ anything not in the cache must not exist; we're not interested
+ in any libraries loaded after that point, only in symbols in
+ libpthread.so. It might not be an appropriate time to look
+ up a symbol, e.g. while we're trying to fetch registers. */
+ return look_up_one_symbol (name, addrp, may_ask_gdb);
+}
+
+int
+thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
+ CORE_ADDR load_module, CORE_ADDR *address)
+{
+ psaddr_t addr;
+ td_err_e err;
+ struct lwp_info *lwp;
+ struct thread_info *saved_thread;
+ struct process_info *proc;
+ struct thread_db *thread_db;
+
+ proc = get_thread_process (thread);
+ thread_db = proc->priv->thread_db;
+
+ /* If the thread layer is not (yet) initialized, fail. */
+ if (thread_db == NULL || !thread_db->all_symbols_looked_up)
+ return TD_ERR;
+
+ /* If td_thr_tls_get_addr is missing rather do not expect td_thr_tlsbase
+ could work. */
+ if (thread_db->td_thr_tls_get_addr_p == NULL
+ || (load_module == 0 && thread_db->td_thr_tlsbase_p == NULL))
+ return -1;
+
+ lwp = get_thread_lwp (thread);
+ if (!lwp->thread_known)
+ find_one_thread (thread->id);
+ if (!lwp->thread_known)
+ return TD_NOTHR;
+
+ saved_thread = current_thread;
+ current_thread = thread;
+
+ if (load_module != 0)
+ {
+ /* Note the cast through uintptr_t: this interface only works if
+ a target address fits in a psaddr_t, which is a host pointer.
+ So a 32-bit debugger can not access 64-bit TLS through this. */
+ err = thread_db->td_thr_tls_get_addr_p (&lwp->th,
+ (psaddr_t) (uintptr_t) load_module,
+ offset, &addr);
+ }
+ else
+ {
+ /* This code path handles the case of -static -pthread executables:
+ https://sourceware.org/ml/libc-help/2014-03/msg00024.html
+ For older GNU libc r_debug.r_map is NULL. For GNU libc after
+ PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
+ The constant number 1 depends on GNU __libc_setup_tls
+ initialization of l_tls_modid to 1. */
+ err = thread_db->td_thr_tlsbase_p (&lwp->th, 1, &addr);
+ addr = (char *) addr + offset;
+ }
+
+ current_thread = saved_thread;
+ if (err == TD_OK)
+ {
+ *address = (CORE_ADDR) (uintptr_t) addr;
+ return 0;
+ }
+ else
+ 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
+thread_db_load_search (void)
+{
+ td_err_e err;
+ struct thread_db *tdb;
+ struct process_info *proc = current_process ();
+
+ gdb_assert (proc->priv->thread_db == NULL);
+
+ tdb = XCNEW (struct thread_db);
+ proc->priv->thread_db = tdb;
+
+ tdb->td_ta_new_p = &td_ta_new;
+
+ /* Attempt to open a connection to the thread library. */
+ err = tdb->td_ta_new_p (&tdb->proc_handle, &tdb->thread_agent);
+ if (err != TD_OK)
+ {
+ if (debug_threads)
+ debug_printf ("td_ta_new(): %s\n", thread_db_err_str (err));
+ free (tdb);
+ proc->priv->thread_db = NULL;
+ return 0;
+ }
+
+ tdb->td_ta_map_lwp2thr_p = &td_ta_map_lwp2thr;
+ tdb->td_thr_get_info_p = &td_thr_get_info;
+ tdb->td_ta_thr_iter_p = &td_ta_thr_iter;
+ tdb->td_symbol_list_p = &td_symbol_list;
+
+ /* These are not essential. */
+ tdb->td_thr_tls_get_addr_p = &td_thr_tls_get_addr;
+ tdb->td_thr_tlsbase_p = &td_thr_tlsbase;
+
+ return 1;
+}
+
+#else
+
+static int
+try_thread_db_load_1 (void *handle)
+{
+ td_err_e err;
+ struct thread_db *tdb;
+ struct process_info *proc = current_process ();
+
+ gdb_assert (proc->priv->thread_db == NULL);
+
+ tdb = XCNEW (struct thread_db);
+ proc->priv->thread_db = tdb;
+
+ tdb->handle = handle;
+
+ /* Initialize pointers to the dynamic library functions we will use.
+ Essential functions first. */
+
+#define CHK(required, a) \
+ do \
+ { \
+ if ((a) == NULL) \
+ { \
+ if (debug_threads) \
+ debug_printf ("dlsym: %s\n", dlerror ()); \
+ if (required) \
+ { \
+ free (tdb); \
+ proc->priv->thread_db = NULL; \
+ return 0; \
+ } \
+ } \
+ } \
+ while (0)
+
+#define TDB_DLSYM(tdb, func) \
+ tdb->func ## _p = (func ## _ftype *) dlsym (tdb->handle, #func)
+
+ CHK (1, TDB_DLSYM (tdb, td_ta_new));
+
+ /* Attempt to open a connection to the thread library. */
+ err = tdb->td_ta_new_p (&tdb->proc_handle, &tdb->thread_agent);
+ if (err != TD_OK)
+ {
+ if (debug_threads)
+ debug_printf ("td_ta_new(): %s\n", thread_db_err_str (err));
+ free (tdb);
+ proc->priv->thread_db = NULL;
+ return 0;
+ }
+
+ CHK (1, TDB_DLSYM (tdb, td_ta_map_lwp2thr));
+ CHK (1, TDB_DLSYM (tdb, td_thr_get_info));
+ CHK (1, TDB_DLSYM (tdb, td_ta_thr_iter));
+ CHK (1, TDB_DLSYM (tdb, td_symbol_list));
+
+ /* These are not essential. */
+ CHK (0, TDB_DLSYM (tdb, td_thr_tls_get_addr));
+ CHK (0, TDB_DLSYM (tdb, td_thr_tlsbase));
+
+#undef CHK
+#undef TDB_DLSYM
+
+ return 1;
+}
+
+#ifdef HAVE_DLADDR
+
+/* Lookup a library in which given symbol resides.
+ Note: this is looking in the GDBSERVER process, not in the inferior.
+ Returns library name, or NULL. */
+
+static const char *
+dladdr_to_soname (const void *addr)
+{
+ Dl_info info;
+
+ if (dladdr (addr, &info) != 0)
+ return info.dli_fname;
+ return NULL;
+}
+
+#endif
+
+static int
+try_thread_db_load (const char *library)
+{
+ void *handle;
+
+ if (debug_threads)
+ debug_printf ("Trying host libthread_db library: %s.\n",
+ library);
+ handle = dlopen (library, RTLD_NOW);
+ if (handle == NULL)
+ {
+ if (debug_threads)
+ debug_printf ("dlopen failed: %s.\n", dlerror ());
+ return 0;
+ }
+
+#ifdef HAVE_DLADDR
+ if (debug_threads && strchr (library, '/') == NULL)
+ {
+ void *td_init;
+
+ td_init = dlsym (handle, "td_init");
+ if (td_init != NULL)
+ {
+ const char *const libpath = dladdr_to_soname (td_init);
+
+ if (libpath != NULL)
+ debug_printf ("Host %s resolved to: %s.\n", library, libpath);
+ }
+ }
+#endif
+
+ if (try_thread_db_load_1 (handle))
+ return 1;
+
+ /* This library "refused" to work on current inferior. */
+ dlclose (handle);
+ return 0;
+}
+
+/* Handle $sdir in libthread-db-search-path.
+ Look for libthread_db in the system dirs, or wherever a plain
+ dlopen(file_without_path) will look.
+ The result is true for success. */
+
+static int
+try_thread_db_load_from_sdir (void)
+{
+ return try_thread_db_load (LIBTHREAD_DB_SO);
+}
+
+/* Try to load libthread_db from directory DIR of length DIR_LEN.
+ The result is true for success. */
+
+static int
+try_thread_db_load_from_dir (const char *dir, size_t dir_len)
+{
+ char path[PATH_MAX];
+
+ if (dir_len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
+ {
+ char *cp = (char *) xmalloc (dir_len + 1);
+
+ memcpy (cp, dir, dir_len);
+ cp[dir_len] = '\0';
+ warning (_("libthread-db-search-path component too long,"
+ " ignored: %s."), cp);
+ free (cp);
+ return 0;
+ }
+
+ memcpy (path, dir, dir_len);
+ path[dir_len] = '/';
+ strcpy (path + dir_len + 1, LIBTHREAD_DB_SO);
+ return try_thread_db_load (path);
+}
+
+/* Search libthread_db_search_path for libthread_db which "agrees"
+ to work on current inferior.
+ The result is true for success. */
+
+static int
+thread_db_load_search (void)
+{
+ int rc = 0;
+
+ if (libthread_db_search_path == NULL)
+ libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
+
+ std::vector<gdb::unique_xmalloc_ptr<char>> dir_vec
+ = dirnames_to_char_ptr_vec (libthread_db_search_path);
+
+ for (const gdb::unique_xmalloc_ptr<char> &this_dir_up : dir_vec)
+ {
+ char *this_dir = this_dir_up.get ();
+ const int pdir_len = sizeof ("$pdir") - 1;
+ size_t this_dir_len;
+
+ this_dir_len = strlen (this_dir);
+
+ if (strncmp (this_dir, "$pdir", pdir_len) == 0
+ && (this_dir[pdir_len] == '\0'
+ || this_dir[pdir_len] == '/'))
+ {
+ /* We don't maintain a list of loaded libraries so we don't know
+ where libpthread lives. We *could* fetch the info, but we don't
+ do that yet. Ignore it. */
+ }
+ else if (strcmp (this_dir, "$sdir") == 0)
+ {
+ if (try_thread_db_load_from_sdir ())
+ {
+ rc = 1;
+ break;
+ }
+ }
+ else
+ {
+ if (try_thread_db_load_from_dir (this_dir, this_dir_len))
+ {
+ rc = 1;
+ break;
+ }
+ }
+ }
+
+ if (debug_threads)
+ debug_printf ("thread_db_load_search returning %d\n", rc);
+ return rc;
+}
+
+#endif /* USE_LIBTHREAD_DB_DIRECTLY */
+
+int
+thread_db_init (void)
+{
+ struct process_info *proc = current_process ();
/* FIXME drow/2004-10-16: This is the "overall process ID", which
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. */
- proc_handle.pid = ((struct inferior_list_entry *)current_inferior)->id;
- err = td_ta_new (&proc_handle, &thread_agent);
- switch (err)
+ if (thread_db_load_search ())
{
- case TD_NOLIBTHREAD:
- /* No thread library was detected. */
- return 0;
-
- case TD_OK:
- /* The thread library was detected. */
-
- if (thread_db_enable_reporting () == 0)
- return 0;
- thread_db_find_new_threads ();
+ /* 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. 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 (!linux_proc_task_list_dir_exists (pid_of (proc)))
+ thread_db_find_new_threads ();
thread_db_look_up_symbols ();
return 1;
+ }
- default:
- warning ("error initializing thread_db library: %s",
- thread_db_err_str (err));
+ return 0;
+}
+
+static void
+switch_to_process (struct process_info *proc)
+{
+ int pid = pid_of (proc);
+
+ current_thread = find_any_thread_of_pid (pid);
+}
+
+/* Disconnect from libthread_db and free resources. */
+
+static void
+disable_thread_event_reporting (struct process_info *proc)
+{
+ struct thread_db *thread_db = proc->priv->thread_db;
+ if (thread_db)
+ {
+ td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
+ td_thr_events_t *event);
+
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+ td_ta_clear_event_p
+ = (td_ta_clear_event_ftype *) dlsym (thread_db->handle,
+ "td_ta_clear_event");
+#else
+ td_ta_clear_event_p = &td_ta_clear_event;
+#endif
+
+ if (td_ta_clear_event_p != NULL)
+ {
+ struct thread_info *saved_thread = current_thread;
+ td_thr_events_t events;
+
+ switch_to_process (proc);
+
+ /* Set the process wide mask saying we aren't interested
+ in any events anymore. */
+ td_event_fillset (&events);
+ (*td_ta_clear_event_p) (thread_db->thread_agent, &events);
+
+ current_thread = saved_thread;
+ }
}
+}
+void
+thread_db_detach (struct process_info *proc)
+{
+ struct thread_db *thread_db = proc->priv->thread_db;
+
+ if (thread_db)
+ {
+ disable_thread_event_reporting (proc);
+ }
+}
+
+/* Disconnect from libthread_db and free resources. */
+
+void
+thread_db_mourn (struct process_info *proc)
+{
+ struct thread_db *thread_db = proc->priv->thread_db;
+ if (thread_db)
+ {
+ td_ta_delete_ftype *td_ta_delete_p;
+
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+ td_ta_delete_p = (td_ta_delete_ftype *) dlsym (thread_db->handle, "td_ta_delete");
+#else
+ td_ta_delete_p = &td_ta_delete;
+#endif
+
+ if (td_ta_delete_p != NULL)
+ (*td_ta_delete_p) (thread_db->thread_agent);
+
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+ dlclose (thread_db->handle);
+#endif /* USE_LIBTHREAD_DB_DIRECTLY */
+
+ free (thread_db);
+ proc->priv->thread_db = NULL;
+ }
+}
+
+/* Handle "set libthread-db-search-path" monitor command and return 1.
+ For any other command, return 0. */
+
+int
+thread_db_handle_monitor_command (char *mon)
+{
+ const char *cmd = "set libthread-db-search-path";
+ size_t cmd_len = strlen (cmd);
+
+ if (strncmp (mon, cmd, cmd_len) == 0
+ && (mon[cmd_len] == '\0'
+ || mon[cmd_len] == ' '))
+ {
+ const char *cp = mon + cmd_len;
+
+ if (libthread_db_search_path != NULL)
+ free (libthread_db_search_path);
+
+ /* Skip leading space (if any). */
+ while (isspace (*cp))
+ ++cp;
+
+ if (*cp == '\0')
+ cp = LIBTHREAD_DB_SEARCH_PATH;
+ libthread_db_search_path = xstrdup (cp);
+
+ monitor_output ("libthread-db-search-path set to `");
+ monitor_output (libthread_db_search_path);
+ monitor_output ("'\n");
+ return 1;
+ }
+
+ /* 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.");
+}
projects / deliverable / binutils-gdb.git / blobdiff