From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14271 invoked by alias); 27 Feb 2006 19:44:21 -0000 Received: (qmail 14259 invoked by uid 22791); 27 Feb 2006 19:44:19 -0000 X-Spam-Check-By: sourceware.org Received: from nevyn.them.org (HELO nevyn.them.org) (66.93.172.17) by sourceware.org (qpsmtpd/0.31.1) with ESMTP; Mon, 27 Feb 2006 19:44:17 +0000 Received: from drow by nevyn.them.org with local (Exim 4.54) id 1FDoI2-0006qk-El for gdb-patches@sourceware.org; Mon, 27 Feb 2006 14:44:14 -0500 Date: Mon, 27 Feb 2006 19:59:00 -0000 From: Daniel Jacobowitz To: gdb-patches@sourceware.org Subject: RFC: Initialize libthread_db at the right time Message-ID: <20060227194414.GA26229@nevyn.them.org> Mail-Followup-To: gdb-patches@sourceware.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.8i X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2006-02/txt/msg00496.txt.bz2 We've had some recurring problems debugging statically linked executables using libthread_db; this patch is the first of several fixes for that. This doesn't do much; it just splits the check out from the new_objfile hook, and calls it from target_post_attach and target_post_startup_inferior in the Linux native target. Earlier versions of this patch used an observer instead, which was silly of me; we only want to do this when we're sitting on top of the Linux native target, not when we're on top of e.g. the remote target. This mostly fixes the not-enabling-libthread_db-when-we-should-be class of problems; there's still one gross hack in remote.c which avoids calling the new objfile hook for remote targets, but that's a mess for another day. Any comments? Otherwise, I'll commit this in a few days. It handles LinuxThreads, but NPTL needs a little push (coming up next). -- Daniel Jacobowitz CodeSourcery 2006-02-27 Daniel Jacobowitz * linux-thread-db.c: Include "linux-nat.h". (check_for_thread_db): New function, split out from thread_db_new_objfile. Remove dead check for active thread_db on inapplicable targets. (thread_db_new_objfile): Call check_for_thread_db. * Makefile.in (linux-thread-db.o): Update. * linux-nat.c (child_post_attach): Call check_for_thread_db. (linux_child_post_startup_inferior): Likewise. (lin_lwp_attach_lwp): Call target_post_attach instead of child_post_attach. * linux-nat.h (check_for_thread_db): New prototype. Index: src/gdb/linux-thread-db.c =================================================================== --- src.orig/gdb/linux-thread-db.c 2006-02-27 12:44:41.000000000 -0500 +++ src/gdb/linux-thread-db.c 2006-02-27 14:36:30.000000000 -0500 @@ -37,6 +37,7 @@ #include "regcache.h" #include "solib-svr4.h" #include "gdbcore.h" +#include "linux-nat.h" #ifdef HAVE_GNU_LIBC_VERSION_H #include @@ -626,59 +627,49 @@ check_thread_signals (void) #endif } -static void -thread_db_new_objfile (struct objfile *objfile) +/* 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) { td_err_e err; + static int already_loaded; /* First time through, report that libthread_db was successfuly loaded. Can't print this in in thread_db_load as, at that stage, - the interpreter and it's console haven't started. The real - problem here is that libthread_db is loaded too early - it should - only be loaded when there is a program to debug. */ - { - static int dejavu; - if (!dejavu) - { - Dl_info info; - const char *library = NULL; - /* Try dladdr. */ - if (dladdr ((*td_ta_new_p), &info) != 0) - library = info.dli_fname; - /* Try dlinfo? */ - if (library == NULL) - /* Paranoid - don't let a NULL path slip through. */ - library = LIBTHREAD_DB_SO; - printf_unfiltered (_("Using host libthread_db library \"%s\".\n"), - library); - dejavu = 1; - } - } + the interpreter and it's console haven't started. */ - /* Don't attempt to use thread_db on targets which can not run - (core files). */ - if (objfile == NULL || !target_has_execution) + if (!already_loaded) { - /* All symbols have been discarded. If the thread_db target is - active, deactivate it now. */ - if (using_thread_db) - { - gdb_assert (proc_handle.pid == 0); - unpush_target (&thread_db_ops); - using_thread_db = 0; - } + Dl_info info; + const char *library = NULL; + if (dladdr ((*td_ta_new_p), &info) != 0) + library = info.dli_fname; + + /* Try dlinfo? */ + + if (library == NULL) + /* Paranoid - don't let a NULL path slip through. */ + library = LIBTHREAD_DB_SO; - goto quit; + printf_unfiltered (_("Using host libthread_db library \"%s\".\n"), + library); + already_loaded = 1; } if (using_thread_db) /* Nothing to do. The thread library was already detected and the target vector was already activated. */ - goto quit; + return; - /* Initialize the structure that identifies the child process. Note - that at this point there is no guarantee that we actually have a - child process. */ + /* 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; + + /* Initialize the structure that identifies the child process. */ proc_handle.pid = GET_PID (inferior_ptid); /* Now attempt to open a connection to the thread library. */ @@ -705,8 +696,14 @@ thread_db_new_objfile (struct objfile *o thread_db_err_str (err)); break; } +} + +static void +thread_db_new_objfile (struct objfile *objfile) +{ + if (objfile != NULL) + check_for_thread_db (); -quit: if (target_new_objfile_chain) target_new_objfile_chain (objfile); } Index: src/gdb/Makefile.in =================================================================== --- src.orig/gdb/Makefile.in 2006-02-27 14:16:21.000000000 -0500 +++ src/gdb/Makefile.in 2006-02-27 14:36:30.000000000 -0500 @@ -2198,7 +2198,7 @@ linux-nat.o: linux-nat.c $(defs_h) $(inf linux-thread-db.o: linux-thread-db.c $(defs_h) $(gdb_assert_h) \ $(gdb_proc_service_h) $(gdb_thread_db_h) $(bfd_h) $(exceptions_h) \ $(gdbthread_h) $(inferior_h) $(symfile_h) $(objfiles_h) $(target_h) \ - $(regcache_h) $(solib_svr4_h) $(gdbcore_h) + $(regcache_h) $(solib_svr4_h) $(gdbcore_h) $(linux_nat_h) lynx-nat.o: lynx-nat.c $(defs_h) $(frame_h) $(inferior_h) $(target_h) \ $(gdbcore_h) $(regcache_h) m2-exp.o: m2-exp.c $(defs_h) $(gdb_string_h) $(expression_h) $(language_h) \ Index: src/gdb/linux-nat.c =================================================================== --- src.orig/gdb/linux-nat.c 2006-02-27 12:47:52.000000000 -0500 +++ src/gdb/linux-nat.c 2006-02-27 14:36:30.000000000 -0500 @@ -334,12 +334,14 @@ void child_post_attach (int pid) { linux_enable_event_reporting (pid_to_ptid (pid)); + check_for_thread_db (); } static void linux_child_post_startup_inferior (ptid_t ptid) { linux_enable_event_reporting (ptid); + check_for_thread_db (); } int @@ -963,7 +965,7 @@ lin_lwp_attach_lwp (ptid_t ptid, int ver gdb_assert (pid == GET_LWP (ptid) && WIFSTOPPED (status) && WSTOPSIG (status)); - child_post_attach (pid); + target_post_attach (pid); lp->stopped = 1; Index: src/gdb/linux-nat.h =================================================================== --- src.orig/gdb/linux-nat.h 2006-02-27 12:56:19.000000000 -0500 +++ src/gdb/linux-nat.h 2006-02-27 14:36:30.000000000 -0500 @@ -65,6 +65,8 @@ struct lwp_info struct lwp_info *next; }; +/* Attempt to initialize libthread_db. */ +void check_for_thread_db (void); /* Find process PID's pending signal set from /proc/pid/status. */ void linux_proc_pending_signals (int pid, sigset_t *pending, sigset_t *blocked, sigset_t *ignored);