| /* Thread management interface, for the remote server for GDB. |
| Copyright (C) 2002-2021 Free Software Foundation, Inc. |
| |
| Contributed by MontaVista Software. |
| |
| 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 3 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, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "server.h" |
| |
| #include "linux-low.h" |
| |
| #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" |
| |
| #ifndef USE_LIBTHREAD_DB_DIRECTLY |
| #include <dlfcn.h> |
| #endif |
| #include <limits.h> |
| #include <ctype.h> |
| |
| struct thread_db |
| { |
| /* Structure that identifies the child process for the |
| <proc_service.h> interface. */ |
| struct ps_prochandle proc_handle; |
| |
| /* Connection to the libthread_db library. */ |
| 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 const char * |
| thread_db_err_str (td_err_e err) |
| { |
| static char buf[64]; |
| |
| switch (err) |
| { |
| case TD_OK: |
| return "generic 'call succeeded'"; |
| case TD_ERR: |
| return "generic error"; |
| case TD_NOTHR: |
| return "no thread to satisfy query"; |
| case TD_NOSV: |
| return "no sync handle to satisfy query"; |
| case TD_NOLWP: |
| return "no LWP to satisfy query"; |
| case TD_BADPH: |
| return "invalid process handle"; |
| case TD_BADTH: |
| return "invalid thread handle"; |
| case TD_BADSH: |
| return "invalid synchronization handle"; |
| case TD_BADTA: |
| return "invalid thread agent"; |
| case TD_BADKEY: |
| return "invalid key"; |
| case TD_NOMSG: |
| return "no event message for getmsg"; |
| case TD_NOFPREGS: |
| return "FPU register set not available"; |
| case TD_NOLIBTHREAD: |
| return "application not linked with libthread"; |
| case TD_NOEVENT: |
| return "requested event is not supported"; |
| case TD_NOCAPAB: |
| return "capability not available"; |
| case TD_DBERR: |
| return "debugger service failed"; |
| case TD_NOAPLIC: |
| return "operation not applicable to"; |
| case TD_NOTSD: |
| return "no thread-specific data for this thread"; |
| case TD_MALLOC: |
| return "malloc failed"; |
| case TD_PARTIALREG: |
| return "only part of register set was written/read"; |
| case TD_NOXREGS: |
| return "X register set not available for this thread"; |
| #ifdef HAVE_TD_VERSION |
| case TD_VERSION: |
| return "version mismatch between libthread_db and libpthread"; |
| #endif |
| default: |
| xsnprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err); |
| return buf; |
| } |
| } |
| |
| #if 0 |
| static char * |
| thread_db_state_str (td_thr_state_e state) |
| { |
| static char buf[64]; |
| |
| switch (state) |
| { |
| case TD_THR_STOPPED: |
| return "stopped by debugger"; |
| case TD_THR_RUN: |
| return "runnable"; |
| case TD_THR_ACTIVE: |
| return "active"; |
| case TD_THR_ZOMBIE: |
| return "zombie"; |
| case TD_THR_SLEEP: |
| return "sleeping"; |
| case TD_THR_STOPPED_ASLEEP: |
| return "stopped by debugger AND blocked"; |
| default: |
| xsnprintf (buf, sizeof (buf), "unknown thread_db state %d", state); |
| return buf; |
| } |
| } |
| #endif |
| |
| /* 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 lwp_info *lwp; |
| struct thread_db *thread_db = current_process ()->priv->thread_db; |
| int lwpid = ptid.lwp (); |
| |
| thread_info *thread = find_thread_ptid (ptid); |
| lwp = get_thread_lwp (thread); |
| if (lwp->thread_known) |
| return 1; |
| |
| /* 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)); |
| |
| 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) |
| debug_printf ("Found thread %ld (LWP %d)\n", |
| (unsigned long) ti.ti_tid, ti.ti_lid); |
| |
| if (lwpid != ti.ti_lid) |
| { |
| warning ("PID mismatch! Expected %ld, got %ld", |
| (long) lwpid, (long) ti.ti_lid); |
| return 0; |
| } |
| |
| /* 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; |
| } |
| |
| /* Attach a thread. Return true on success. */ |
| |
| static int |
| attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p) |
| { |
| struct process_info *proc = current_process (); |
| int pid = pid_of (proc); |
| ptid_t ptid = ptid_t (pid, ti_p->ti_lid); |
| struct lwp_info *lwp; |
| int err; |
| |
| if (debug_threads) |
| debug_printf ("Attaching to thread %ld (LWP %d)\n", |
| (unsigned long) ti_p->ti_tid, ti_p->ti_lid); |
| err = the_linux_target->attach_lwp (ptid); |
| if (err != 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 ()); |
| |
| 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; |
| |
| 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 |
| find_new_threads_callback (const td_thrhandle_t *th_p, void *data) |
| { |
| td_thrinfo_t ti; |
| td_err_e err; |
| struct thread_db *thread_db = current_process ()->priv->thread_db; |
| |
| 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; |
| |
| 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; |
| } |
| |
| static void |
| 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; |
| |
| /* 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)); |
| } |
| |
| /* Cache all future symbols that thread_db might request. We can not |
| request symbols at arbitrary states in the remote protocol, only |
| when the client tells us that new symbols are available. So when |
| we load the thread library, make sure to check the entire list. */ |
| |
| static void |
| thread_db_look_up_symbols (void) |
| { |
| struct thread_db *thread_db = current_process ()->priv->thread_db; |
| const char **sym_list; |
| CORE_ADDR 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) |
| { |
| 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. |
| |
| This isn't the only place in gdbserver that assumes that the first |
| process in the list is the thread group leader. */ |
| |
| 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; |
| } |
| |
| /* 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."); |
| } |