/* Thread management interface, for the remote server for GDB.
- Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008, 2009
- 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 "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;
-#include <stdint.h>
+ /* Connection to the libthread_db library. */
+ td_thragent_t *thread_agent;
-/* Structure that identifies the child process for the
- <proc_service.h> interface. */
-static struct ps_prochandle proc_handle;
+ /* 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;
-/* Connection to the libthread_db library. */
-static td_thragent_t *thread_agent;
+#ifndef USE_LIBTHREAD_DB_DIRECTLY
+ /* Handle of the libthread_db from dlopen. */
+ void *handle;
+#endif
-static int find_one_thread (int);
+ /* 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 const char *
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 int
-thread_db_create_event (CORE_ADDR where)
-{
- td_event_msg_t msg;
- td_err_e err;
- struct lwp_info *lwp;
-
- if (debug_threads)
- fprintf (stderr, "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 = td_ta_event_getmsg (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_inferior);
- if (lwp->thread_known == 0)
- find_one_thread (lwp->lwpid);
-
- /* msg.event == TD_EVENT_CREATE */
-
- find_new_threads_callback (msg.th_p, NULL);
-
- return 0;
-}
-
-#if 0
-static int
-thread_db_death_event (CORE_ADDR where)
-{
- if (debug_threads)
- fprintf (stderr, "Thread death event.\n");
-
- return 0;
-}
-#endif
-
-static int
-thread_db_enable_reporting ()
-{
- 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
-
- err = td_ta_set_event (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 = 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
-
- return 1;
-}
+/* Get thread info about PTID, accessing memory via the current
+ thread. */
static int
-find_one_thread (int lwpid)
+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.lwp ();
- inferior = (struct thread_info *) find_inferior_id (&all_threads, lwpid);
- lwp = get_thread_lwp (inferior);
+ thread_info *thread = find_thread_ptid (ptid);
+ lwp = get_thread_lwp (thread);
if (lwp->thread_known)
return 1;
/* Get information about this thread. */
- err = td_ta_map_lwp2thr (thread_agent, lwp->lwpid, &th);
+ 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));
- err = td_thr_get_info (&th, &ti);
+ err = thread_db->td_thr_get_info_p (&th, &ti);
if (err != TD_OK)
error ("Cannot get thread info for LWP %d: %s",
lwpid, thread_db_err_str (err));
if (debug_threads)
- fprintf (stderr, "Found thread %ld (LWP %d)\n",
- ti.ti_tid, ti.ti_lid);
+ debug_printf ("Found thread %ld (LWP %d)\n",
+ (unsigned long) ti.ti_tid, ti.ti_lid);
- if (lwp->lwpid != ti.ti_lid)
+ if (lwpid != ti.ti_lid)
{
warning ("PID mismatch! Expected %ld, got %ld",
- (long) lwp->lwpid, (long) ti.ti_lid);
+ (long) lwpid, (long) ti.ti_lid);
return 0;
}
- if (thread_db_use_events)
- {
- err = td_thr_event_enable (&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;
}
-static void
-maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
+/* Attach a thread. Return true on success. */
+
+static int
+attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
{
- td_err_e err;
- struct thread_info *inferior;
+ 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;
-
- inferior = (struct thread_info *) find_inferior_id (&all_threads,
- ti_p->ti_lid);
- if (inferior != NULL)
- return;
+ int err;
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);
- inferior = (struct thread_info *) find_inferior_id (&all_threads,
- ti_p->ti_lid);
- if (inferior == NULL)
+ 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 ("Could not attach to thread %ld (LWP %d)\n",
- ti_p->ti_tid, ti_p->ti_lid);
- return;
- }
+ std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err);
- lwp = inferior_target_data (inferior);
+ 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;
+ }
+
+ lwp = find_lwp_pid (ptid);
+ gdb_assert (lwp != NULL);
lwp->thread_known = 1;
lwp->th = *th_p;
+ lwp->thread_handle = ti_p->ti_tid;
- if (thread_db_use_events)
- {
- 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;
+}
+
+/* Attach thread if we haven't seen it yet.
+ Increment *COUNTER if we have attached a new thread.
+ Return false on failure. */
+
+static int
+maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p,
+ int *counter)
+{
+ struct lwp_info *lwp;
+
+ lwp = find_lwp_pid (ptid_t (ti_p->ti_lid));
+ if (lwp != NULL)
+ return 1;
+
+ if (!attach_thread (th_p, ti_p))
+ return 0;
+
+ if (counter != NULL)
+ *counter += 1;
+
+ 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 (all_threads.head->id) == 0)
+ 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_look_up_one_symbol (const char *name, CORE_ADDR *addrp)
+{
+ 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)
{
-#if HAVE_TD_THR_TLS_GET_ADDR
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 (lwp->lwpid);
+ find_one_thread (thread->id);
if (!lwp->thread_known)
return TD_NOTHR;
- /* 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 = td_thr_tls_get_addr (&lwp->th, (psaddr_t) (uintptr_t) load_module,
- offset, &addr);
+ 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;
}
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
- return -1;
+
+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 (int use_events)
+thread_db_init (void)
{
- int err;
+ 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;
- /* Allow new symbol lookups. */
- all_symbols_looked_up = 0;
+ if (thread_db_load_search ())
+ {
+ /* 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;
+ }
+
+ return 0;
+}
- thread_db_use_events = use_events;
+static void
+switch_to_process (struct process_info *proc)
+{
+ int pid = pid_of (proc);
- err = td_ta_new (&proc_handle, &thread_agent);
- switch (err)
+ 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)
{
- case TD_NOLIBTHREAD:
- /* No thread library was detected. */
- return 0;
+ td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
+ td_thr_events_t *event);
- case TD_OK:
- /* The thread library was detected. */
+#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 (use_events && thread_db_enable_reporting () == 0)
- return 0;
- thread_db_find_new_threads ();
- thread_db_look_up_symbols ();
- all_symbols_looked_up = 1;
- return 1;
+ if (td_ta_clear_event_p != NULL)
+ {
+ struct thread_info *saved_thread = current_thread;
+ td_thr_events_t events;
- default:
- warning ("error initializing thread_db library: %s",
- thread_db_err_str (err));
+ 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