linux: Add maintenance commands to test libthread_db
This commit adds two new commands which may be used to test thread
debugging libraries used by GDB:
* "maint check libthread-db" tests the thread debugging library GDB
is using for the current inferior.
* "maint set/show check-libthread-db" selects whether libthread_db
tests should be run automatically as libthread_db is auto-loaded.
The default is to not run tests automatically.
The test itself is a basic integrity check exercising all libthread_db
functions used by GDB on GNU/Linux systems. By extension this also
exercises the proc_service functions provided by GDB that libthread_db
uses.
This functionality is useful for NPTL developers and libthread_db
developers. It could also prove useful investigating bugs reported
against GDB where the thread debugging library or GDB's proc_service
layer is suspect.
gdb/ChangeLog:
* linux-thread-db.c (valprint.h): New include.
(struct check_thread_db_info): New structure.
(check_thread_db_on_load, tdb_testinfo): New static globals.
(check_thread_db, check_thread_db_callback): New functions.
(try_thread_db_load_1): Run integrity checks if requested.
(maintenance_check_libthread_db): New function.
(_initialize_thread_db): Register "maint check libthread-db"
and "maint set/show check-libthread-db".
gdb/doc/ChangeLog:
* gdb.texinfo (Maintenance Commands): Document "maint check
libthread-db" and "maint set/show check-libthread-db".
gdb/testsuite/ChangeLog:
* gdb.threads/check-libthread-db.exp: New file.
* gdb.threads/check-libthread-db.c: Likewise.
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1c77dea..f1233bb 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,14 @@
+2017-11-22 Gary Benson <gbenson@redhat.com>
+
+ * linux-thread-db.c (valprint.h): New include.
+ (struct check_thread_db_info): New structure.
+ (check_thread_db_on_load, tdb_testinfo): New static globals.
+ (check_thread_db, check_thread_db_callback): New functions.
+ (try_thread_db_load_1): Run integrity checks if requested.
+ (maintenance_check_libthread_db): New function.
+ (_initialize_thread_db): Register "maint check libthread-db"
+ and "maint set/show check-libthread-db".
+
2017-11-21 Jerome Guitton <guitton@adacore.com>
* ravenscar-thread.c (ravenscar_wait): Update inferior ptid
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 2d8f5af..c4b958c 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-22 Gary Benson <gbenson@redhat.com>
+
+ * gdb.texinfo (Maintenance Commands): Document "maint check
+ libthread-db" and "maint set/show check-libthread-db".
+
2017-11-16 Phil Muldoon <pmuldoon@redhat.com>
* python.texi (Basic Python): Add rbreak documentation.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 29d4789..4d7a7b1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -34981,6 +34981,11 @@
Check that the target descriptions dynamically created by @value{GDBN}
equal the descriptions created from XML files found in @var{dir}.
+@kindex maint check libthread-db
+@item maint check libthread-db
+Run integrity checks on the current inferior's thread debugging
+library.
+
@kindex maint print dummy-frames
@item maint print dummy-frames
Prints the contents of @value{GDBN}'s internal dummy-frame stack.
@@ -35288,6 +35293,14 @@
@end enumerate
@end table
+@kindex maint set check-libthread-db
+@kindex maint show check-libthread-db
+@item maint set check-libthread-db [on|off]
+@itemx maint show check-libthread-db
+Control whether @value{GDBN} should run integrity checks on inferior
+specific thread debugging libraries as they are loaded. The default
+is not to perform such checks.
+
@kindex maint space
@cindex memory used by commands
@item maint space @var{value}
diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index ea032fc..d1fdb33 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -46,6 +46,7 @@
#include <ctype.h>
#include "nat/linux-namespaces.h"
#include <algorithm>
+#include "valprint.h"
/* GNU/Linux libthread_db support.
@@ -80,6 +81,10 @@
by the "set auto-load libthread-db" command. */
static int auto_load_thread_db = 1;
+/* Set to non-zero if load-time libthread_db tests have been enabled
+ by the "maintenence set check-libthread-db" command. */
+static int check_thread_db_on_load = 0;
+
/* "show" command for the auto_load_thread_db configuration variable. */
static void
@@ -493,6 +498,216 @@
return NULL;
}
+/* State for check_thread_db_callback. */
+
+struct check_thread_db_info
+{
+ /* The libthread_db under test. */
+ struct thread_db_info *info;
+
+ /* True if progress should be logged. */
+ bool log_progress;
+
+ /* True if the callback was called. */
+ bool threads_seen;
+};
+
+static struct check_thread_db_info *tdb_testinfo;
+
+/* Callback for check_thread_db. */
+
+static int
+check_thread_db_callback (const td_thrhandle_t *th, void *arg)
+{
+ gdb_assert (tdb_testinfo != NULL);
+ tdb_testinfo->threads_seen = true;
+
+#define LOG(fmt, args...) \
+ do \
+ { \
+ if (tdb_testinfo->log_progress) \
+ { \
+ debug_printf (fmt, ## args); \
+ gdb_flush (gdb_stdlog); \
+ } \
+ } \
+ while (0)
+
+#define __CHECK(expr, args...) \
+ do \
+ { \
+ if (!(expr)) \
+ { \
+ LOG (" ... FAIL!\n"); \
+ error (args); \
+ } \
+ } \
+ while (0)
+
+#define CHECK(expr) \
+ __CHECK (expr, "(%s) == false", #expr)
+
+#define CHECK_CALL(func, args...) \
+ do \
+ { \
+ td_err_e __err = tdb_testinfo->info->func ## _p (args); \
+ \
+ __CHECK (__err == TD_OK, _("%s failed: %s"), #func, \
+ thread_db_err_str (__err)); \
+ } \
+ while (0)
+
+ LOG (" Got thread");
+
+ /* Check td_ta_thr_iter passed consistent arguments. */
+ CHECK (th != NULL);
+ CHECK (arg == (void *) tdb_testinfo);
+ CHECK (th->th_ta_p == tdb_testinfo->info->thread_agent);
+
+ LOG (" %s", core_addr_to_string_nz ((CORE_ADDR) th->th_unique));
+
+ /* Check td_thr_get_info. */
+ td_thrinfo_t ti;
+ CHECK_CALL (td_thr_get_info, th, &ti);
+
+ LOG (" => %d", ti.ti_lid);
+
+ CHECK (ti.ti_ta_p == th->th_ta_p);
+ CHECK (ti.ti_tid == (thread_t) th->th_unique);
+
+ /* Check td_ta_map_lwp2thr. */
+ td_thrhandle_t th2;
+ memset (&th2, 23, sizeof (td_thrhandle_t));
+ CHECK_CALL (td_ta_map_lwp2thr, th->th_ta_p, ti.ti_lid, &th2);
+
+ LOG (" => %s", core_addr_to_string_nz ((CORE_ADDR) th2.th_unique));
+
+ CHECK (memcmp (th, &th2, sizeof (td_thrhandle_t)) == 0);
+
+ /* Attempt TLS access. Assuming errno is TLS, this calls
+ thread_db_get_thread_local_address, which in turn calls
+ td_thr_tls_get_addr for live inferiors or td_thr_tlsbase
+ for core files. This test is skipped if the thread has
+ not been recorded; proceeding in that case would result
+ in the test having the side-effect of noticing threads
+ which seems wrong.
+
+ Note that in glibc's libthread_db td_thr_tls_get_addr is
+ a thin wrapper around td_thr_tlsbase; this check always
+ hits the bulk of the code.
+
+ Note also that we don't actually check any libthread_db
+ calls are made, we just assume they were; future changes
+ to how GDB accesses TLS could result in this passing
+ without exercising the calls it's supposed to. */
+ ptid_t ptid = ptid_build (tdb_testinfo->info->pid, ti.ti_lid, 0);
+ struct thread_info *thread_info = find_thread_ptid (ptid);
+ if (thread_info != NULL && thread_info->priv != NULL)
+ {
+ LOG ("; errno");
+
+ scoped_restore_current_thread restore_current_thread;
+ switch_to_thread (ptid);
+
+ expression_up expr = parse_expression ("errno");
+ struct value *val = evaluate_expression (expr.get ());
+
+ if (tdb_testinfo->log_progress)
+ {
+ struct value_print_options opts;
+
+ get_user_print_options (&opts);
+ LOG (" = ");
+ value_print (val, gdb_stdlog, &opts);
+ }
+ }
+
+ LOG (" ... OK\n");
+
+#undef LOG
+#undef __CHECK
+#undef CHECK
+#undef CHECK_CALL
+
+ return 0;
+}
+
+/* Run integrity checks on the dlopen()ed libthread_db described by
+ INFO. Returns true on success, displays a warning and returns
+ false on failure. Logs progress messages to gdb_stdlog during
+ the test if LOG_PROGRESS is true. */
+
+static bool
+check_thread_db (struct thread_db_info *info, bool log_progress)
+{
+ bool test_passed = true;
+
+ if (log_progress)
+ debug_printf (_("Running libthread_db integrity checks:\n"));
+
+ /* GDB avoids using td_ta_thr_iter wherever possible (see comment
+ in try_thread_db_load_1 below) so in order to test it we may
+ have to locate it ourselves. */
+ td_ta_thr_iter_ftype *td_ta_thr_iter_p = info->td_ta_thr_iter_p;
+ if (td_ta_thr_iter_p == NULL)
+ {
+ void *thr_iter = verbose_dlsym (info->handle, "td_ta_thr_iter");
+ if (thr_iter == NULL)
+ return 0;
+
+ td_ta_thr_iter_p = (td_ta_thr_iter_ftype *) thr_iter;
+ }
+
+ /* Set up the test state we share with the callback. */
+ gdb_assert (tdb_testinfo == NULL);
+ struct check_thread_db_info tdb_testinfo_buf;
+ tdb_testinfo = &tdb_testinfo_buf;
+
+ memset (tdb_testinfo, 0, sizeof (struct check_thread_db_info));
+ tdb_testinfo->info = info;
+ tdb_testinfo->log_progress = log_progress;
+
+ /* td_ta_thr_iter shouldn't be used on running processes. */
+ linux_stop_and_wait_all_lwps ();
+
+ TRY
+ {
+ td_err_e err = td_ta_thr_iter_p (info->thread_agent,
+ check_thread_db_callback,
+ tdb_testinfo,
+ TD_THR_ANY_STATE,
+ TD_THR_LOWEST_PRIORITY,
+ TD_SIGNO_MASK,
+ TD_THR_ANY_USER_FLAGS);
+
+ if (err != TD_OK)
+ error (_("td_ta_thr_iter failed: %s"), thread_db_err_str (err));
+
+ if (!tdb_testinfo->threads_seen)
+ error (_("no threads seen"));
+ }
+ CATCH (except, RETURN_MASK_ERROR)
+ {
+ if (warning_pre_print)
+ fputs_unfiltered (warning_pre_print, gdb_stderr);
+
+ exception_fprintf (gdb_stderr, except,
+ _("libthread_db integrity checks failed: "));
+
+ test_passed = false;
+ }
+ END_CATCH
+
+ if (test_passed && log_progress)
+ debug_printf (_("libthread_db integrity checks passed.\n"));
+
+ tdb_testinfo = NULL;
+
+ linux_unstop_all_lwps ();
+
+ return test_passed;
+}
+
/* Attempt to initialize dlopen()ed libthread_db, described by INFO.
Return 1 on success.
Failure could happen if libthread_db does not have symbols we expect,
@@ -586,6 +801,13 @@
#undef TDB_DLSYM
#undef CHK
+ /* Run integrity checks if requested. */
+ if (check_thread_db_on_load)
+ {
+ if (!check_thread_db (info, libthread_db_debug != 0))
+ return 0;
+ }
+
if (info->td_ta_thr_iter_p == NULL)
{
struct lwp_info *lp;
@@ -1704,6 +1926,24 @@
uiout->message (_("No auto-loaded libthread-db.\n"));
}
+/* Implement 'maintenance check libthread-db'. */
+
+static void
+maintenance_check_libthread_db (const char *args, int from_tty)
+{
+ int inferior_pid = ptid_get_pid (inferior_ptid);
+ struct thread_db_info *info;
+
+ if (inferior_pid == 0)
+ error (_("No inferior running"));
+
+ info = get_thread_db_info (inferior_pid);
+ if (info == NULL)
+ error (_("No libthread_db loaded"));
+
+ check_thread_db (info, true);
+}
+
static void
init_thread_db_ops (void)
{
@@ -1780,6 +2020,23 @@
Usage: info auto-load libthread-db"),
auto_load_info_cmdlist_get ());
+ add_cmd ("libthread-db", class_maintenance,
+ maintenance_check_libthread_db, _("\
+Run integrity checks on the current inferior's libthread_db."),
+ &maintenancechecklist);
+
+ add_setshow_boolean_cmd ("check-libthread-db",
+ class_maintenance,
+ &check_thread_db_on_load, _("\
+Set whether to check libthread_db at load time."), _("\
+Show whether to check libthread_db at load time."), _("\
+If enabled GDB will run integrity checks on inferior specific libthread_db\n\
+as they are loaded."),
+ NULL,
+ NULL,
+ &maintenance_set_cmdlist,
+ &maintenance_show_cmdlist);
+
/* Add ourselves to objfile event chain. */
observer_attach_new_objfile (thread_db_new_objfile);
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7434105..449f84a 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-22 Gary Benson <gbenson@redhat.com>
+
+ * gdb.threads/check-libthread-db.exp: New file.
+ * gdb.threads/check-libthread-db.c: Likewise.
+
2017-11-21 Ulrich Weigand <uweigand@de.ibm.com>
* gdb.arch/ppc-longdouble.exp: New file.
diff --git a/gdb/testsuite/gdb.threads/check-libthread-db.c b/gdb/testsuite/gdb.threads/check-libthread-db.c
new file mode 100644
index 0000000..22be229
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/check-libthread-db.c
@@ -0,0 +1,66 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2017 Free Software Foundation, Inc.
+
+ 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 <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <errno.h>
+
+static void
+break_here (void)
+{
+}
+
+static void *
+thread_routine (void *arg)
+{
+ errno = 42;
+
+ break_here ();
+
+ while (1)
+ sleep (1);
+
+ return NULL;
+}
+
+int
+main (int argc, char *argv)
+{
+ pthread_t the_thread;
+ int err;
+
+ err = pthread_create (&the_thread, NULL, thread_routine, NULL);
+ if (err != 0)
+ {
+ fprintf (stderr, "pthread_create: %s (%d)\n", strerror (err), err);
+ exit (EXIT_FAILURE);
+ }
+
+ errno = 23;
+
+ err = pthread_join (the_thread, NULL);
+ if (err != 0)
+ {
+ fprintf (stderr, "pthread_join: %s (%d)\n", strerror (err), err);
+ exit (EXIT_FAILURE);
+ }
+
+ exit (EXIT_SUCCESS);
+}
diff --git a/gdb/testsuite/gdb.threads/check-libthread-db.exp b/gdb/testsuite/gdb.threads/check-libthread-db.exp
new file mode 100644
index 0000000..3990cf3
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/check-libthread-db.exp
@@ -0,0 +1,114 @@
+# Copyright 2017 Free Software Foundation, Inc.
+
+# 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/>.
+
+# This test only works for native processes on Linux.
+if { ![isnative] || [is_remote host] || [target_info exists use_gdb_stub]
+ || ![istarget *-linux*] } {
+ continue
+}
+
+standard_testfile
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
+ executable debug] != "" } {
+ return -1
+}
+
+# TEST 1: Manual check with libthread_db not loaded.
+
+clean_restart ${binfile}
+
+gdb_test "maint show check-libthread-db" \
+ "Whether to check libthread_db at load time is off."
+
+gdb_test_no_output "set stop-on-solib-events 1"
+gdb_run_cmd
+gdb_test "" \
+ ".*Stopped due to shared library event.*no libraries added or removed.*"
+
+gdb_test "maint check libthread-db" \
+ "No libthread_db loaded" \
+ "libpthread.so not loaded"
+
+
+# TEST 2: Manual check with NPTL uninitialized.
+# libthread_db should fake a single thread with th_unique == NULL.
+
+gdb_test "continue" \
+ ".*Stopped due to shared library event.*Inferior loaded .*libpthread.*"
+
+gdb_test_sequence "maint check libthread-db" \
+ "libpthread.so not initialized (manual)" {
+ "\[\r\n\]+Running libthread_db integrity checks:"
+ "\[\r\n\]+\[ \]+Got thread 0x0 => \[0-9\]+ => 0x0 ... OK"
+ "\[\r\n\]+libthread_db integrity checks passed."
+ }
+
+
+# TEST 3: Manual check with NPTL fully operational.
+
+gdb_test_no_output "set stop-on-solib-events 0"
+gdb_breakpoint break_here
+gdb_continue_to_breakpoint break_here
+
+gdb_test_sequence "maint check libthread-db" \
+ "libpthread.so fully initialized (manual)" {
+ "\[\r\n\]+Running libthread_db integrity checks:"
+ "\[\r\n\]+\[ \]+Got thread 0x\[1-9a-f\]\[0-9a-f\]+ => \[0-9\]+ => 0x\[1-9a-f\]\[0-9a-f\]+; errno = 23 ... OK"
+ "\[\r\n\]+\[ \]+Got thread 0x\[1-9a-f\]\[0-9a-f\]+ => \[0-9\]+ => 0x\[1-9a-f\]\[0-9a-f\]+; errno = 42 ... OK"
+ "\[\r\n\]+libthread_db integrity checks passed."
+ }
+
+
+# TEST 4: Automated check with NPTL uninitialized.
+
+clean_restart ${binfile}
+
+gdb_test_no_output "maint set check-libthread-db 1"
+gdb_test_no_output "set debug libthread-db 1"
+gdb_breakpoint break_here
+gdb_run_cmd
+
+gdb_test_sequence "" \
+ "libpthread.so not initialized (automated)" {
+ "\[\r\n\]+Running libthread_db integrity checks:"
+ "\[\r\n\]+\[ \]+Got thread 0x0 => \[0-9\]+ => 0x0 ... OK"
+ "\[\r\n\]+libthread_db integrity checks passed."
+ "\[\r\n\]+[Thread debugging using libthread_db enabled]"
+ }
+
+
+# TEST 5: Automated check with NPTL fully operational.
+
+clean_restart ${binfile}
+
+gdb_test_no_output "maint set check-libthread-db 1"
+gdb_test_no_output "set debug libthread-db 1"
+
+set test_spawn_id [spawn_wait_for_attach $binfile]
+set testpid [spawn_id_get_pid $test_spawn_id]
+
+gdb_test_sequence "attach $testpid" \
+ "libpthread.so fully initialized (automated)" {
+ "\[\r\n\]+Running libthread_db integrity checks:"
+ "\[\r\n\]+\[ \]+Got thread 0x\[1-9a-f\]\[0-9a-f\]+ => \[0-9\]+ => 0x\[1-9a-f\]\[0-9a-f\]+ ... OK"
+ "\[\r\n\]+\[ \]+Got thread 0x\[1-9a-f\]\[0-9a-f\]+ => \[0-9\]+ => 0x\[1-9a-f\]\[0-9a-f\]+ ... OK"
+ "\[\r\n\]+libthread_db integrity checks passed."
+ "\[\r\n\]+[Thread debugging using libthread_db enabled]"
+ }
+
+
+gdb_exit
+kill_wait_spawned_process $test_spawn_id
