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[/] [openrisc/] [trunk/] [gnu-stable/] [gdb-7.2/] [gdb/] [linux-thread-db.c] - Rev 850
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/* libthread_db assisted debugging support, generic parts. Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. 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 "defs.h" #include "gdb_assert.h" #include <dlfcn.h> #include "gdb_proc_service.h" #include "gdb_thread_db.h" #include "bfd.h" #include "command.h" #include "exceptions.h" #include "gdbcmd.h" #include "gdbthread.h" #include "inferior.h" #include "symfile.h" #include "objfiles.h" #include "target.h" #include "regcache.h" #include "solib.h" #include "solib-svr4.h" #include "gdbcore.h" #include "observer.h" #include "linux-nat.h" #include <signal.h> #ifdef HAVE_GNU_LIBC_VERSION_H #include <gnu/libc-version.h> #endif /* GNU/Linux libthread_db support. libthread_db is a library, provided along with libpthread.so, which exposes the internals of the thread library to a debugger. It allows GDB to find existing threads, new threads as they are created, thread IDs (usually, the result of pthread_self), and thread-local variables. The libthread_db interface originates on Solaris, where it is both more powerful and more complicated. This implementation only works for LinuxThreads and NPTL, the two glibc threading libraries. It assumes that each thread is permanently assigned to a single light-weight process (LWP). libthread_db-specific information is stored in the "private" field of struct thread_info. When the field is NULL we do not yet have information about the new thread; this could be temporary (created, but the thread library's data structures do not reflect it yet) or permanent (created using clone instead of pthread_create). Process IDs managed by linux-thread-db.c match those used by linux-nat.c: a common PID for all processes, an LWP ID for each thread, and no TID. We save the TID in private. Keeping it out of the ptid_t prevents thread IDs changing when libpthread is loaded or unloaded. */ static char *libthread_db_search_path; /* If we're running on GNU/Linux, we must explicitly attach to any new threads. */ /* This module's target vector. */ static struct target_ops thread_db_ops; /* Non-zero if we have determined the signals used by the threads library. */ static int thread_signals; static sigset_t thread_stop_set; static sigset_t thread_print_set; struct thread_db_info { struct thread_db_info *next; /* Process id this object refers to. */ int pid; /* Handle from dlopen for libthread_db.so. */ void *handle; /* 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; /* True if we need to apply the workaround for glibc/BZ5983. When we catch a PTRACE_O_TRACEFORK, and go query the child's thread list, nptl_db returns the parent's threads in addition to the new (single) child thread. If this flag is set, we do extra work to be able to ignore such stale entries. */ int need_stale_parent_threads_check; /* Location of the 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. */ CORE_ADDR td_create_bp_addr; /* Location of the thread death event breakpoint. */ CORE_ADDR td_death_bp_addr; /* Pointers to the libthread_db functions. */ td_err_e (*td_init_p) (void); td_err_e (*td_ta_new_p) (struct ps_prochandle * ps, td_thragent_t **ta); td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt, td_thrhandle_t *__th); td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta, lwpid_t lwpid, td_thrhandle_t *th); td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta, td_thr_iter_f *callback, void *cbdata_p, td_thr_state_e state, int ti_pri, sigset_t *ti_sigmask_p, unsigned int ti_user_flags); td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta, td_event_e event, td_notify_t *ptr); td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta, td_thr_events_t *event); td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta, td_thr_events_t *event); td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta, td_event_msg_t *msg); td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th); td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th, td_thrinfo_t *infop); td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th, int event); td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th, psaddr_t map_address, size_t offset, psaddr_t *address); }; /* List of known processes using thread_db, and the required bookkeeping. */ struct thread_db_info *thread_db_list; static void thread_db_find_new_threads_1 (ptid_t ptid); static void thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new); /* Add the current inferior to the list of processes using libpthread. Return a pointer to the newly allocated object that was added to THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing LIBTHREAD_DB_SO. */ static struct thread_db_info * add_thread_db_info (void *handle) { struct thread_db_info *info; info = xcalloc (1, sizeof (*info)); info->pid = ptid_get_pid (inferior_ptid); info->handle = handle; info->need_stale_parent_threads_check = 1; info->next = thread_db_list; thread_db_list = info; return info; } /* Return the thread_db_info object representing the bookkeeping related to process PID, if any; NULL otherwise. */ static struct thread_db_info * get_thread_db_info (int pid) { struct thread_db_info *info; for (info = thread_db_list; info; info = info->next) if (pid == info->pid) return info; return NULL; } /* When PID has exited or has been detached, we no longer want to keep track of it as using libpthread. Call this function to discard thread_db related info related to PID. Note that this closes LIBTHREAD_DB_SO's dlopen'ed handle. */ static void delete_thread_db_info (int pid) { struct thread_db_info *info, *info_prev; info_prev = NULL; for (info = thread_db_list; info; info_prev = info, info = info->next) if (pid == info->pid) break; if (info == NULL) return; if (info->handle != NULL) dlclose (info->handle); if (info_prev) info_prev->next = info->next; else thread_db_list = info->next; xfree (info); } /* Prototypes for local functions. */ static int attach_thread (ptid_t ptid, const td_thrhandle_t *th_p, const td_thrinfo_t *ti_p); static void detach_thread (ptid_t ptid); /* Use "struct private_thread_info" to cache thread state. This is a substantial optimization. */ struct private_thread_info { /* Flag set when we see a TD_DEATH event for this thread. */ unsigned int dying:1; /* Cached thread state. */ td_thrhandle_t th; thread_t tid; }; static 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 THREAD_DB_HAS_TD_NOTALLOC case TD_NOTALLOC: return "thread has not yet allocated TLS for given module"; #endif #ifdef THREAD_DB_HAS_TD_VERSION case TD_VERSION: return "versions of libpthread and libthread_db do not match"; #endif #ifdef THREAD_DB_HAS_TD_NOTLS case TD_NOTLS: return "there is no TLS segment in the given module"; #endif default: snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err); return buf; } } /* Return 1 if any threads have been registered. There may be none if the threading library is not fully initialized yet. */ static int have_threads_callback (struct thread_info *thread, void *args) { int pid = * (int *) args; if (ptid_get_pid (thread->ptid) != pid) return 0; return thread->private != NULL; } static int have_threads (ptid_t ptid) { int pid = ptid_get_pid (ptid); return iterate_over_threads (have_threads_callback, &pid) != NULL; } struct thread_get_info_inout { struct thread_info *thread_info; struct thread_db_info *thread_db_info; }; /* A callback function for td_ta_thr_iter, which we use to map all threads to LWPs. THP is a handle to the current thread; if INFOP is not NULL, the struct thread_info associated with this thread is returned in *INFOP. If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise, zero is returned to indicate success. */ static int thread_get_info_callback (const td_thrhandle_t *thp, void *argp) { td_thrinfo_t ti; td_err_e err; ptid_t thread_ptid; struct thread_get_info_inout *inout; struct thread_db_info *info; inout = argp; info = inout->thread_db_info; err = info->td_thr_get_info_p (thp, &ti); if (err != TD_OK) error (_("thread_get_info_callback: cannot get thread info: %s"), thread_db_err_str (err)); /* Fill the cache. */ thread_ptid = ptid_build (info->pid, ti.ti_lid, 0); inout->thread_info = find_thread_ptid (thread_ptid); /* In the case of a zombie thread, don't continue. We don't want to attach to it thinking it is a new thread. */ if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE) return TD_THR_ZOMBIE; if (inout->thread_info == NULL) { /* New thread. Attach to it now (why wait?). */ if (!have_threads (thread_ptid)) thread_db_find_new_threads_1 (thread_ptid); else attach_thread (thread_ptid, thp, &ti); inout->thread_info = find_thread_ptid (thread_ptid); gdb_assert (inout->thread_info != NULL); } return 0; } /* Convert between user-level thread ids and LWP ids. */ static ptid_t thread_from_lwp (ptid_t ptid) { td_thrhandle_t th; td_err_e err; struct thread_db_info *info; struct thread_get_info_inout io = {0}; /* This ptid comes from linux-nat.c, which should always fill in the LWP. */ gdb_assert (GET_LWP (ptid) != 0); info = get_thread_db_info (GET_PID (ptid)); /* Access an lwp we know is stopped. */ info->proc_handle.ptid = ptid; err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th); if (err != TD_OK) error (_("Cannot find user-level thread for LWP %ld: %s"), GET_LWP (ptid), thread_db_err_str (err)); /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the event thread has already died. If another gdb interface has called thread_alive() previously, the thread won't be found on the thread list anymore. In that case, we don't want to process this ptid anymore to avoid the possibility of later treating it as a newly discovered thread id that we should add to the list. Thus, we return a -1 ptid which is also how the thread list marks a dead thread. */ io.thread_db_info = info; io.thread_info = NULL; if (thread_get_info_callback (&th, &io) == TD_THR_ZOMBIE && io.thread_info == NULL) return minus_one_ptid; gdb_assert (ptid_get_tid (ptid) == 0); return ptid; } /* Attach to lwp PTID, doing whatever else is required to have this LWP under the debugger's control --- e.g., enabling event reporting. Returns true on success. */ int thread_db_attach_lwp (ptid_t ptid) { td_thrhandle_t th; td_thrinfo_t ti; td_err_e err; struct thread_db_info *info; info = get_thread_db_info (GET_PID (ptid)); if (info == NULL) return 0; /* This ptid comes from linux-nat.c, which should always fill in the LWP. */ gdb_assert (GET_LWP (ptid) != 0); /* Access an lwp we know is stopped. */ info->proc_handle.ptid = ptid; /* If we have only looked at the first thread before libpthread was initialized, we may not know its thread ID yet. Make sure we do before we add another thread to the list. */ if (!have_threads (ptid)) thread_db_find_new_threads_1 (ptid); err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th); if (err != TD_OK) /* Cannot find user-level thread. */ return 0; err = info->td_thr_get_info_p (&th, &ti); if (err != TD_OK) { warning (_("Cannot get thread info: %s"), thread_db_err_str (err)); return 0; } attach_thread (ptid, &th, &ti); return 1; } static void * verbose_dlsym (void *handle, const char *name) { void *sym = dlsym (handle, name); if (sym == NULL) warning (_("Symbol \"%s\" not found in libthread_db: %s"), name, dlerror ()); return sym; } static td_err_e enable_thread_event (int event, CORE_ADDR *bp) { td_notify_t notify; td_err_e err; struct thread_db_info *info; info = get_thread_db_info (GET_PID (inferior_ptid)); /* Access an lwp we know is stopped. */ info->proc_handle.ptid = inferior_ptid; /* Get the breakpoint address for thread EVENT. */ err = info->td_ta_event_addr_p (info->thread_agent, event, ¬ify); if (err != TD_OK) return err; /* Set up the breakpoint. */ gdb_assert (exec_bfd); (*bp) = (gdbarch_convert_from_func_ptr_addr (target_gdbarch, /* Do proper sign extension for the target. */ (bfd_get_sign_extend_vma (exec_bfd) > 0 ? (CORE_ADDR) (intptr_t) notify.u.bptaddr : (CORE_ADDR) (uintptr_t) notify.u.bptaddr), ¤t_target)); create_thread_event_breakpoint (target_gdbarch, *bp); return TD_OK; } static void enable_thread_event_reporting (void) { td_thr_events_t events; td_err_e err; #ifdef HAVE_GNU_LIBC_VERSION_H const char *libc_version; int libc_major, libc_minor; #endif struct thread_db_info *info; info = get_thread_db_info (GET_PID (inferior_ptid)); /* We cannot use the thread event reporting facility if these functions aren't available. */ if (info->td_ta_event_addr_p == NULL || info->td_ta_set_event_p == NULL || info->td_ta_event_getmsg_p == NULL || info->td_thr_event_enable_p == NULL) return; /* Set the process wide mask saying which events we're interested in. */ td_event_emptyset (&events); td_event_addset (&events, TD_CREATE); #ifdef HAVE_GNU_LIBC_VERSION_H /* The event reporting facility is broken for TD_DEATH events in glibc 2.1.3, so don't enable it if we have glibc but a lower version. */ libc_version = gnu_get_libc_version (); if (sscanf (libc_version, "%d.%d", &libc_major, &libc_minor) == 2 && (libc_major > 2 || (libc_major == 2 && libc_minor > 1))) #endif td_event_addset (&events, TD_DEATH); err = info->td_ta_set_event_p (info->thread_agent, &events); if (err != TD_OK) { warning (_("Unable to set global thread event mask: %s"), thread_db_err_str (err)); return; } /* Delete previous thread event breakpoints, if any. */ remove_thread_event_breakpoints (); info->td_create_bp_addr = 0; info->td_death_bp_addr = 0; /* Set up the thread creation event. */ err = enable_thread_event (TD_CREATE, &info->td_create_bp_addr); if (err != TD_OK) { warning (_("Unable to get location for thread creation breakpoint: %s"), thread_db_err_str (err)); return; } /* Set up the thread death event. */ err = enable_thread_event (TD_DEATH, &info->td_death_bp_addr); if (err != TD_OK) { warning (_("Unable to get location for thread death breakpoint: %s"), thread_db_err_str (err)); return; } } /* Same as thread_db_find_new_threads_1, but silently ignore errors. */ static void thread_db_find_new_threads_silently (ptid_t ptid) { volatile struct gdb_exception except; TRY_CATCH (except, RETURN_MASK_ERROR) { thread_db_find_new_threads_2 (ptid, 1); } if (except.reason < 0 && info_verbose) { exception_fprintf (gdb_stderr, except, "Warning: thread_db_find_new_threads_silently: "); } } /* Lookup a library in which given symbol resides. Note: this is looking in GDB 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; } /* Attempt to initialize dlopen()ed libthread_db, described by HANDLE. Return 1 on success. Failure could happen if libthread_db does not have symbols we expect, or when it refuses to work with the current inferior (e.g. due to version mismatch between libthread_db and libpthread). */ static int try_thread_db_load_1 (struct thread_db_info *info) { td_err_e err; /* Initialize pointers to the dynamic library functions we will use. Essential functions first. */ info->td_init_p = verbose_dlsym (info->handle, "td_init"); if (info->td_init_p == NULL) return 0; err = info->td_init_p (); if (err != TD_OK) { warning (_("Cannot initialize libthread_db: %s"), thread_db_err_str (err)); return 0; } info->td_ta_new_p = verbose_dlsym (info->handle, "td_ta_new"); if (info->td_ta_new_p == NULL) return 0; /* Initialize the structure that identifies the child process. */ info->proc_handle.ptid = inferior_ptid; /* Now attempt to open a connection to the thread library. */ err = info->td_ta_new_p (&info->proc_handle, &info->thread_agent); if (err != TD_OK) { if (info_verbose) printf_unfiltered (_("td_ta_new failed: %s\n"), thread_db_err_str (err)); else switch (err) { case TD_NOLIBTHREAD: #ifdef THREAD_DB_HAS_TD_VERSION case TD_VERSION: #endif /* The errors above are not unexpected and silently ignored: they just mean we haven't found correct version of libthread_db yet. */ break; default: warning (_("td_ta_new failed: %s"), thread_db_err_str (err)); } return 0; } info->td_ta_map_id2thr_p = verbose_dlsym (info->handle, "td_ta_map_id2thr"); if (info->td_ta_map_id2thr_p == NULL) return 0; info->td_ta_map_lwp2thr_p = verbose_dlsym (info->handle, "td_ta_map_lwp2thr"); if (info->td_ta_map_lwp2thr_p == NULL) return 0; info->td_ta_thr_iter_p = verbose_dlsym (info->handle, "td_ta_thr_iter"); if (info->td_ta_thr_iter_p == NULL) return 0; info->td_thr_validate_p = verbose_dlsym (info->handle, "td_thr_validate"); if (info->td_thr_validate_p == NULL) return 0; info->td_thr_get_info_p = verbose_dlsym (info->handle, "td_thr_get_info"); if (info->td_thr_get_info_p == NULL) return 0; /* These are not essential. */ info->td_ta_event_addr_p = dlsym (info->handle, "td_ta_event_addr"); info->td_ta_set_event_p = dlsym (info->handle, "td_ta_set_event"); info->td_ta_clear_event_p = dlsym (info->handle, "td_ta_clear_event"); info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg"); info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable"); info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr"); printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n")); if (info_verbose || *libthread_db_search_path) { const char *library; library = dladdr_to_soname (*info->td_ta_new_p); if (library == NULL) library = LIBTHREAD_DB_SO; printf_unfiltered (_("Using host libthread_db library \"%s\".\n"), library); } /* The thread library was detected. Activate the thread_db target if this is the first process using it. */ if (thread_db_list->next == NULL) push_target (&thread_db_ops); enable_thread_event_reporting (); /* There appears to be a bug in glibc-2.3.6: calls to td_thr_get_info fail with TD_ERR for statically linked executables if td_thr_get_info is called before glibc has initialized itself. Silently ignore such errors, and let gdb enumerate threads again later. */ thread_db_find_new_threads_silently (inferior_ptid); return 1; } /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute, relative, or just LIBTHREAD_DB. */ static int try_thread_db_load (const char *library) { void *handle; struct thread_db_info *info; if (info_verbose) printf_unfiltered (_("Trying host libthread_db library: %s.\n"), library); handle = dlopen (library, RTLD_NOW); if (handle == NULL) { if (info_verbose) printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ()); return 0; } if (info_verbose && 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) printf_unfiltered (_("Host %s resolved to: %s.\n"), library, libpath); } } info = add_thread_db_info (handle); if (try_thread_db_load_1 (info)) return 1; /* This library "refused" to work on current inferior. */ delete_thread_db_info (GET_PID (inferior_ptid)); return 0; } /* Search libthread_db_search_path for libthread_db which "agrees" to work on current inferior. */ static int thread_db_load_search (void) { char path[PATH_MAX]; const char *search_path = libthread_db_search_path; int rc = 0; while (*search_path) { const char *end = strchr (search_path, ':'); if (end) { size_t len = end - search_path; if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path)) { char *cp = xmalloc (len + 1); memcpy (cp, search_path, len); cp[len] = '\0'; warning (_("libthread_db_search_path component too long," " ignored: %s."), cp); xfree (cp); search_path += len + 1; continue; } memcpy (path, search_path, len); path[len] = '\0'; search_path += len + 1; } else { size_t len = strlen (search_path); if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path)) { warning (_("libthread_db_search_path component too long," " ignored: %s."), search_path); break; } memcpy (path, search_path, len + 1); search_path += len; } strcat (path, "/"); strcat (path, LIBTHREAD_DB_SO); if (try_thread_db_load (path)) { rc = 1; break; } } if (rc == 0) rc = try_thread_db_load (LIBTHREAD_DB_SO); return rc; } /* Attempt to load and initialize libthread_db. Return 1 on success. */ static int thread_db_load (void) { struct objfile *obj; struct thread_db_info *info; info = get_thread_db_info (GET_PID (inferior_ptid)); if (info != NULL) return 1; /* Don't attempt to use thread_db on targets which can not run (executables not running yet, core files) for now. */ if (!target_has_execution) return 0; /* Don't attempt to use thread_db for remote targets. */ if (!target_can_run (¤t_target)) return 0; if (thread_db_load_search ()) return 1; /* None of the libthread_db's on our search path, not the system default ones worked. If the executable is dynamically linked against libpthread, try loading libthread_db from the same directory. */ ALL_OBJFILES (obj) if (libpthread_name_p (obj->name)) { char path[PATH_MAX], *cp; gdb_assert (strlen (obj->name) < sizeof (path)); strcpy (path, obj->name); cp = strrchr (path, '/'); if (cp == NULL) { warning (_("Expected absolute pathname for libpthread in the" " inferior, but got %s."), path); } else if (cp + 1 + strlen (LIBTHREAD_DB_SO) + 1 > path + sizeof (path)) { warning (_("Unexpected: path to libpthread in the inferior is" " too long: %s"), path); } else { strcpy (cp + 1, LIBTHREAD_DB_SO); if (try_thread_db_load (path)) return 1; } warning (_("Unable to find libthread_db matching inferior's thread" " library, thread debugging will not be available.")); return 0; } /* Either this executable isn't using libpthread at all, or it is statically linked. Since we can't easily distinguish these two cases, no warning is issued. */ return 0; } static void disable_thread_event_reporting (struct thread_db_info *info) { if (info->td_ta_clear_event_p != NULL) { td_thr_events_t events; /* Set the process wide mask saying we aren't interested in any events anymore. */ td_event_fillset (&events); info->td_ta_clear_event_p (info->thread_agent, &events); } info->td_create_bp_addr = 0; info->td_death_bp_addr = 0; } static void check_thread_signals (void) { if (!thread_signals) { sigset_t mask; int i; lin_thread_get_thread_signals (&mask); sigemptyset (&thread_stop_set); sigemptyset (&thread_print_set); for (i = 1; i < NSIG; i++) { if (sigismember (&mask, i)) { if (signal_stop_update (target_signal_from_host (i), 0)) sigaddset (&thread_stop_set, i); if (signal_print_update (target_signal_from_host (i), 0)) sigaddset (&thread_print_set, i); thread_signals = 1; } } } } /* Check whether thread_db is usable. This function is called when an inferior is created (or otherwise acquired, e.g. attached to) and when new shared libraries are loaded into a running process. */ void check_for_thread_db (void) { /* Do nothing if we couldn't load libthread_db.so.1. */ if (!thread_db_load ()) return; } static void thread_db_new_objfile (struct objfile *objfile) { /* This observer must always be called with inferior_ptid set correctly. */ if (objfile != NULL) check_for_thread_db (); } /* Attach to a new thread. This function is called when we receive a TD_CREATE event or when we iterate over all threads and find one that wasn't already in our list. Returns true on success. */ static int attach_thread (ptid_t ptid, const td_thrhandle_t *th_p, const td_thrinfo_t *ti_p) { struct private_thread_info *private; struct thread_info *tp = NULL; td_err_e err; struct thread_db_info *info; /* If we're being called after a TD_CREATE event, we may already know about this thread. There are two ways this can happen. We may have iterated over all threads between the thread creation and the TD_CREATE event, for instance when the user has issued the `info threads' command before the SIGTRAP for hitting the thread creation breakpoint was reported. Alternatively, the thread may have exited and a new one been created with the same thread ID. In the first case we don't need to do anything; in the second case we should discard information about the dead thread and attach to the new one. */ if (in_thread_list (ptid)) { tp = find_thread_ptid (ptid); gdb_assert (tp != NULL); /* If tp->private is NULL, then GDB is already attached to this thread, but we do not know anything about it. We can learn about it here. This can only happen if we have some other way besides libthread_db to notice new threads (i.e. PTRACE_EVENT_CLONE); assume the same mechanism notices thread exit, so this can not be a stale thread recreated with the same ID. */ if (tp->private != NULL) { if (!tp->private->dying) return 0; delete_thread (ptid); tp = NULL; } } check_thread_signals (); if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE) return 0; /* A zombie thread -- do not attach. */ /* Under GNU/Linux, we have to attach to each and every thread. */ if (tp == NULL && lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0) return 0; /* Construct the thread's private data. */ private = xmalloc (sizeof (struct private_thread_info)); memset (private, 0, sizeof (struct private_thread_info)); /* A thread ID of zero may mean the thread library has not initialized yet. But we shouldn't even get here if that's the case. FIXME: if we change GDB to always have at least one thread in the thread list this will have to go somewhere else; maybe private == NULL until the thread_db target claims it. */ gdb_assert (ti_p->ti_tid != 0); private->th = *th_p; private->tid = ti_p->ti_tid; /* Add the thread to GDB's thread list. */ if (tp == NULL) tp = add_thread_with_info (ptid, private); else tp->private = private; info = get_thread_db_info (GET_PID (ptid)); /* Enable thread event reporting for this thread. */ err = info->td_thr_event_enable_p (th_p, 1); if (err != TD_OK) error (_("Cannot enable thread event reporting for %s: %s"), target_pid_to_str (ptid), thread_db_err_str (err)); return 1; } static void detach_thread (ptid_t ptid) { struct thread_info *thread_info; /* Don't delete the thread now, because it still reports as active until it has executed a few instructions after the event breakpoint - if we deleted it now, "info threads" would cause us to re-attach to it. Just mark it as having had a TD_DEATH event. This means that we won't delete it from our thread list until we notice that it's dead (via prune_threads), or until something re-uses its thread ID. We'll report the thread exit when the underlying LWP dies. */ thread_info = find_thread_ptid (ptid); gdb_assert (thread_info != NULL && thread_info->private != NULL); thread_info->private->dying = 1; } static void thread_db_detach (struct target_ops *ops, char *args, int from_tty) { struct target_ops *target_beneath = find_target_beneath (ops); struct thread_db_info *info; info = get_thread_db_info (GET_PID (inferior_ptid)); if (info) { disable_thread_event_reporting (info); /* Delete the old thread event breakpoints. Note that unlike when mourning, we can remove them here because there's still a live inferior to poke at. In any case, GDB will not try to insert anything in the inferior when removing a breakpoint. */ remove_thread_event_breakpoints (); delete_thread_db_info (GET_PID (inferior_ptid)); } target_beneath->to_detach (target_beneath, args, from_tty); /* NOTE: From this point on, inferior_ptid is null_ptid. */ /* If there are no more processes using libpthread, detach the thread_db target ops. */ if (!thread_db_list) unpush_target (&thread_db_ops); } /* Check if PID is currently stopped at the location of a thread event breakpoint location. If it is, read the event message and act upon the event. */ static void check_event (ptid_t ptid) { struct regcache *regcache = get_thread_regcache (ptid); struct gdbarch *gdbarch = get_regcache_arch (regcache); td_event_msg_t msg; td_thrinfo_t ti; td_err_e err; CORE_ADDR stop_pc; int loop = 0; struct thread_db_info *info; info = get_thread_db_info (GET_PID (ptid)); /* Bail out early if we're not at a thread event breakpoint. */ stop_pc = regcache_read_pc (regcache) - gdbarch_decr_pc_after_break (gdbarch); if (stop_pc != info->td_create_bp_addr && stop_pc != info->td_death_bp_addr) return; /* Access an lwp we know is stopped. */ info->proc_handle.ptid = ptid; /* If we have only looked at the first thread before libpthread was initialized, we may not know its thread ID yet. Make sure we do before we add another thread to the list. */ if (!have_threads (ptid)) thread_db_find_new_threads_1 (ptid); /* If we are at a create breakpoint, we do not know what new lwp was created and cannot specifically locate the event message for it. We have to call td_ta_event_getmsg() to get the latest message. Since we have no way of correlating whether the event message we get back corresponds to our breakpoint, we must loop and read all event messages, processing them appropriately. This guarantees we will process the correct message before continuing from the breakpoint. Currently, death events are not enabled. If they are enabled, the death event can use the td_thr_event_getmsg() interface to get the message specifically for that lwp and avoid looping below. */ loop = 1; do { err = info->td_ta_event_getmsg_p (info->thread_agent, &msg); if (err != TD_OK) { if (err == TD_NOMSG) return; error (_("Cannot get thread event message: %s"), thread_db_err_str (err)); } err = info->td_thr_get_info_p (msg.th_p, &ti); if (err != TD_OK) error (_("Cannot get thread info: %s"), thread_db_err_str (err)); ptid = ptid_build (GET_PID (ptid), ti.ti_lid, 0); switch (msg.event) { case TD_CREATE: /* Call attach_thread whether or not we already know about a thread with this thread ID. */ attach_thread (ptid, msg.th_p, &ti); break; case TD_DEATH: if (!in_thread_list (ptid)) error (_("Spurious thread death event.")); detach_thread (ptid); break; default: error (_("Spurious thread event.")); } } while (loop); } static ptid_t thread_db_wait (struct target_ops *ops, ptid_t ptid, struct target_waitstatus *ourstatus, int options) { struct thread_db_info *info; struct target_ops *beneath = find_target_beneath (ops); ptid = beneath->to_wait (beneath, ptid, ourstatus, options); if (ourstatus->kind == TARGET_WAITKIND_IGNORE) return ptid; if (ourstatus->kind == TARGET_WAITKIND_EXITED || ourstatus->kind == TARGET_WAITKIND_SIGNALLED) return ptid; info = get_thread_db_info (GET_PID (ptid)); /* If this process isn't using thread_db, we're done. */ if (info == NULL) return ptid; if (ourstatus->kind == TARGET_WAITKIND_EXECD) { /* New image, it may or may not end up using thread_db. Assume not unless we find otherwise. */ delete_thread_db_info (GET_PID (ptid)); if (!thread_db_list) unpush_target (&thread_db_ops); /* Thread event breakpoints are deleted by update_breakpoints_after_exec. */ return ptid; } /* If we do not know about the main thread yet, this would be a good time to find it. */ if (ourstatus->kind == TARGET_WAITKIND_STOPPED && !have_threads (ptid)) thread_db_find_new_threads_1 (ptid); if (ourstatus->kind == TARGET_WAITKIND_STOPPED && ourstatus->value.sig == TARGET_SIGNAL_TRAP) /* Check for a thread event. */ check_event (ptid); if (have_threads (ptid)) { /* Change ptids back into the higher level PID + TID format. If the thread is dead and no longer on the thread list, we will get back a dead ptid. This can occur if the thread death event gets postponed by other simultaneous events. In such a case, we want to just ignore the event and continue on. */ ptid = thread_from_lwp (ptid); if (GET_PID (ptid) == -1) ourstatus->kind = TARGET_WAITKIND_SPURIOUS; } return ptid; } static void thread_db_mourn_inferior (struct target_ops *ops) { struct target_ops *target_beneath = find_target_beneath (ops); delete_thread_db_info (GET_PID (inferior_ptid)); target_beneath->to_mourn_inferior (target_beneath); /* Delete the old thread event breakpoints. Do this after mourning the inferior, so that we don't try to uninsert them. */ remove_thread_event_breakpoints (); /* Detach thread_db target ops. */ if (!thread_db_list) unpush_target (ops); } struct callback_data { struct thread_db_info *info; int new_threads; }; static int find_new_threads_callback (const td_thrhandle_t *th_p, void *data) { td_thrinfo_t ti; td_err_e err; ptid_t ptid; struct thread_info *tp; struct callback_data *cb_data = data; struct thread_db_info *info = cb_data->info; err = info->td_thr_get_info_p (th_p, &ti); if (err != TD_OK) error (_("find_new_threads_callback: cannot get thread info: %s"), thread_db_err_str (err)); if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE) return 0; /* A zombie -- ignore. */ if (ti.ti_tid == 0) { /* A thread ID of zero means that this is the main thread, but glibc has not yet initialized thread-local storage and the pthread library. We do not know what the thread's TID will be yet. Just enable event reporting and otherwise ignore it. */ /* In that case, we're not stopped in a fork syscall and don't need this glibc bug workaround. */ info->need_stale_parent_threads_check = 0; err = info->td_thr_event_enable_p (th_p, 1); if (err != TD_OK) error (_("Cannot enable thread event reporting for LWP %d: %s"), (int) ti.ti_lid, thread_db_err_str (err)); return 0; } /* Ignore stale parent threads, caused by glibc/BZ5983. This is a bit expensive, as it needs to open /proc/pid/status, so try to avoid doing the work if we know we don't have to. */ if (info->need_stale_parent_threads_check) { int tgid = linux_proc_get_tgid (ti.ti_lid); if (tgid != -1 && tgid != info->pid) return 0; } ptid = ptid_build (info->pid, ti.ti_lid, 0); tp = find_thread_ptid (ptid); if (tp == NULL || tp->private == NULL) { if (attach_thread (ptid, th_p, &ti)) cb_data->new_threads += 1; else /* Problem attaching this thread; perhaps it exited before we could attach it? This could mean that the thread list inside glibc itself is in inconsistent state, and libthread_db could go on looping forever (observed with glibc-2.3.6). To prevent that, terminate iteration: thread_db_find_new_threads_2 will retry. */ return 1; } return 0; } /* Helper for thread_db_find_new_threads_2. Returns number of new threads found. */ static int find_new_threads_once (struct thread_db_info *info, int iteration, td_err_e *errp) { volatile struct gdb_exception except; struct callback_data data; td_err_e err = TD_ERR; data.info = info; data.new_threads = 0; TRY_CATCH (except, RETURN_MASK_ERROR) { /* Iterate over all user-space threads to discover new threads. */ err = info->td_ta_thr_iter_p (info->thread_agent, find_new_threads_callback, &data, TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY, TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS); } if (info_verbose) { if (except.reason < 0) exception_fprintf (gdb_stderr, except, "Warning: find_new_threads_once: "); printf_filtered (_("Found %d new threads in iteration %d.\n"), data.new_threads, iteration); } if (errp != NULL) *errp = err; return data.new_threads; } /* Search for new threads, accessing memory through stopped thread PTID. If UNTIL_NO_NEW is true, repeat searching until several searches in a row do not discover any new threads. */ static void thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new) { td_err_e err; struct lwp_info *lp; struct thread_db_info *info; int pid = ptid_get_pid (ptid); int i, loop; /* In linux, we can only read memory through a stopped lwp. */ ALL_LWPS (lp, ptid) if (lp->stopped && ptid_get_pid (lp->ptid) == pid) break; if (!lp) /* There is no stopped thread. Bail out. */ return; info = get_thread_db_info (GET_PID (ptid)); /* Access an lwp we know is stopped. */ info->proc_handle.ptid = ptid; if (until_no_new) { /* 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 (i = 0, loop = 0; loop < 4; ++i, ++loop) if (find_new_threads_once (info, i, NULL) != 0) /* Found some new threads. Restart the loop from beginning. */ loop = -1; } else { find_new_threads_once (info, 0, &err); if (err != TD_OK) error (_("Cannot find new threads: %s"), thread_db_err_str (err)); } } static void thread_db_find_new_threads_1 (ptid_t ptid) { thread_db_find_new_threads_2 (ptid, 0); } static int update_thread_core (struct lwp_info *info, void *closure) { info->core = linux_nat_core_of_thread_1 (info->ptid); return 0; } static void thread_db_find_new_threads (struct target_ops *ops) { struct thread_db_info *info; info = get_thread_db_info (GET_PID (inferior_ptid)); if (info == NULL) return; thread_db_find_new_threads_1 (inferior_ptid); iterate_over_lwps (minus_one_ptid /* iterate over all */, update_thread_core, NULL); } static char * thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid) { struct thread_info *thread_info = find_thread_ptid (ptid); struct target_ops *beneath; if (thread_info != NULL && thread_info->private != NULL) { static char buf[64]; thread_t tid; tid = thread_info->private->tid; snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)", tid, GET_LWP (ptid)); return buf; } beneath = find_target_beneath (ops); if (beneath->to_pid_to_str (beneath, ptid)) return beneath->to_pid_to_str (beneath, ptid); return normal_pid_to_str (ptid); } /* Return a string describing the state of the thread specified by INFO. */ static char * thread_db_extra_thread_info (struct thread_info *info) { if (info->private == NULL) return NULL; if (info->private->dying) return "Exiting"; return NULL; } /* Get the address of the thread local variable in load module LM which is stored at OFFSET within the thread local storage for thread PTID. */ static CORE_ADDR thread_db_get_thread_local_address (struct target_ops *ops, ptid_t ptid, CORE_ADDR lm, CORE_ADDR offset) { struct thread_info *thread_info; struct target_ops *beneath; /* If we have not discovered any threads yet, check now. */ if (!have_threads (ptid)) thread_db_find_new_threads_1 (ptid); /* Find the matching thread. */ thread_info = find_thread_ptid (ptid); if (thread_info != NULL && thread_info->private != NULL) { td_err_e err; psaddr_t address; struct thread_db_info *info; info = get_thread_db_info (GET_PID (ptid)); /* glibc doesn't provide the needed interface. */ if (!info->td_thr_tls_get_addr_p) throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR, _("No TLS library support")); /* Caller should have verified that lm != 0. */ gdb_assert (lm != 0); /* Finally, get the address of the variable. */ /* 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 = info->td_thr_tls_get_addr_p (&thread_info->private->th, (psaddr_t)(uintptr_t) lm, offset, &address); #ifdef THREAD_DB_HAS_TD_NOTALLOC /* The memory hasn't been allocated, yet. */ if (err == TD_NOTALLOC) /* Now, if libthread_db provided the initialization image's address, we *could* try to build a non-lvalue value from the initialization image. */ throw_error (TLS_NOT_ALLOCATED_YET_ERROR, _("TLS not allocated yet")); #endif /* Something else went wrong. */ if (err != TD_OK) throw_error (TLS_GENERIC_ERROR, (("%s")), thread_db_err_str (err)); /* Cast assuming host == target. Joy. */ /* Do proper sign extension for the target. */ gdb_assert (exec_bfd); return (bfd_get_sign_extend_vma (exec_bfd) > 0 ? (CORE_ADDR) (intptr_t) address : (CORE_ADDR) (uintptr_t) address); } beneath = find_target_beneath (ops); if (beneath->to_get_thread_local_address) return beneath->to_get_thread_local_address (beneath, ptid, lm, offset); else throw_error (TLS_GENERIC_ERROR, _("TLS not supported on this target")); } /* Callback routine used to find a thread based on the TID part of its PTID. */ static int thread_db_find_thread_from_tid (struct thread_info *thread, void *data) { long *tid = (long *) data; if (thread->private->tid == *tid) return 1; return 0; } /* Implement the to_get_ada_task_ptid target method for this target. */ static ptid_t thread_db_get_ada_task_ptid (long lwp, long thread) { struct thread_info *thread_info; thread_db_find_new_threads_1 (inferior_ptid); thread_info = iterate_over_threads (thread_db_find_thread_from_tid, &thread); gdb_assert (thread_info != NULL); return (thread_info->ptid); } static void thread_db_resume (struct target_ops *ops, ptid_t ptid, int step, enum target_signal signo) { struct target_ops *beneath = find_target_beneath (ops); struct thread_db_info *info; if (ptid_equal (ptid, minus_one_ptid)) info = get_thread_db_info (GET_PID (inferior_ptid)); else info = get_thread_db_info (GET_PID (ptid)); /* This workaround is only needed for child fork lwps stopped in a PTRACE_O_TRACEFORK event. When the inferior is resumed, the workaround can be disabled. */ if (info) info->need_stale_parent_threads_check = 0; beneath->to_resume (beneath, ptid, step, signo); } static void init_thread_db_ops (void) { thread_db_ops.to_shortname = "multi-thread"; thread_db_ops.to_longname = "multi-threaded child process."; thread_db_ops.to_doc = "Threads and pthreads support."; thread_db_ops.to_detach = thread_db_detach; thread_db_ops.to_wait = thread_db_wait; thread_db_ops.to_resume = thread_db_resume; thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior; thread_db_ops.to_find_new_threads = thread_db_find_new_threads; thread_db_ops.to_pid_to_str = thread_db_pid_to_str; thread_db_ops.to_stratum = thread_stratum; thread_db_ops.to_has_thread_control = tc_schedlock; thread_db_ops.to_get_thread_local_address = thread_db_get_thread_local_address; thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info; thread_db_ops.to_get_ada_task_ptid = thread_db_get_ada_task_ptid; thread_db_ops.to_magic = OPS_MAGIC; } /* Provide a prototype to silence -Wmissing-prototypes. */ extern initialize_file_ftype _initialize_thread_db; void _initialize_thread_db (void) { init_thread_db_ops (); add_target (&thread_db_ops); /* Defer loading of libthread_db.so until inferior is running. This allows gdb to load correct libthread_db for a given executable -- there could be mutiple versions of glibc, compiled with LinuxThreads or NPTL, and until there is a running inferior, we can't tell which libthread_db is the correct one to load. */ libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH); add_setshow_optional_filename_cmd ("libthread-db-search-path", class_support, &libthread_db_search_path, _("\ Set search path for libthread_db."), _("\ Show the current search path or libthread_db."), _("\ This path is used to search for libthread_db to be loaded into \ gdb itself."), NULL, NULL, &setlist, &showlist); /* Add ourselves to objfile event chain. */ observer_attach_new_objfile (thread_db_new_objfile); }
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