[PATCH 27/31] Testcases for stepping over thread exit syscall (PR gdb/27338)

Pedro Alves
2022-12-12T20:33:51Z

From: Simon Marchi <simon.marchi@efficios.com>

- New in this series version:

- gdb.threads/step-over-thread-exit.exp has a couple new testing axes:

- non-stop vs all-stop.

- in non-stop have the testcase explicitly stop all threads in
non-stop mode, vs not doing that.

- bail out of gdb.threads/step-over-thread-exit.exp early on FAIL, to
avoid cascading timeouts.

Add new gdb.threads/step-over-thread-exit.exp and
gdb.threads/step-over-thread-exit-while-stop-all-threads.exp
testcases, exercising stepping over thread exit syscall. These make
use of lib/my-syscalls.S to define the exit syscall.

Co-authored-by: Pedro Alves <pedro@palves.net>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
Change-Id: Ie8b2c5747db99b7023463a897a8390d9e814a9c9
---
...-over-thread-exit-while-stop-all-threads.c | 77 +++++++++++
...ver-thread-exit-while-stop-all-threads.exp | 69 ++++++++++
.../gdb.threads/step-over-thread-exit.c | 52 ++++++++
.../gdb.threads/step-over-thread-exit.exp | 126 ++++++++++++++++++
gdb/testsuite/lib/my-syscalls.S | 4 +
gdb/testsuite/lib/my-syscalls.h | 5 +
6 files changed, 333 insertions(+)
create mode 100644 gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.c
create mode 100644 gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.exp
create mode 100644 gdb/testsuite/gdb.threads/step-over-thread-exit.c
create mode 100644 gdb/testsuite/gdb.threads/step-over-thread-exit.exp

diff --git a/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.c b/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.c
new file mode 100644
index 00000000000..2699ad5d714
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.c
@@ -0,0 +1,77 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021-2022 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 <unistd.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include "../lib/my-syscalls.h"
+
+#define NUM_THREADS 32
+
+static void *
+stepper_over_exit_thread (void *v)
+{
+ my_exit (0);
+
+ /* my_exit above should exit the thread, we don't expect to reach
+ here. */
+ abort ();
+}
+
+static void *
+spawner_thread (void *v)
+{
+ for (;;)
+ {
+ pthread_t threads[NUM_THREADS];
+ int i;
+
+ for (i = 0; i < NUM_THREADS; i++)
+ pthread_create (&threads[i], NULL, stepper_over_exit_thread, NULL);
+
+ for (i = 0; i < NUM_THREADS; i++)
+ pthread_join (threads[i], NULL);
+ }
+}
+
+static void
+break_here (void)
+{
+}
+
+static void *
+breakpoint_hitter_thread (void *v)
+{
+ for (;;)
+ break_here ();
+}
+
+int
+main ()
+{
+ pthread_t breakpoint_hitter;
+ pthread_t spawner;
+
+ alarm (60);
+
+ pthread_create (&spawner, NULL, spawner_thread, NULL);
+ pthread_create (&breakpoint_hitter, NULL, breakpoint_hitter_thread, NULL);
+
+ pthread_join (spawner, NULL);
+
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.exp b/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.exp
new file mode 100644
index 00000000000..6a46aff700e
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/step-over-thread-exit-while-stop-all-threads.exp
@@ -0,0 +1,69 @@
+# Copyright 2021-2022 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/>.
+
+# Test stepping over a breakpoint installed on an instruction that
+# exits the thread, while another thread is repeatedly hitting a
+# breakpoint, causing GDB to stop all threads.
+
+standard_testfile .c
+
+set syscalls_src $srcdir/lib/my-syscalls.S
+
+if { [build_executable "failed to prepare" $testfile \
+ [list $srcfile $syscalls_src] {debug pthreads}] == -1 } {
+ return
+}
+
+proc test {displaced-stepping target-non-stop} {
+ save_vars ::GDBFLAGS {
+ append ::GDBFLAGS " -ex \"maintenance set target-non-stop ${target-non-stop}\""
+ clean_restart $::binfile
+ }
+
+ gdb_test_no_output "set displaced-stepping ${displaced-stepping}"
+
+ if { ![runto_main] } {
+ return
+ }
+
+ # The "stepper over exit" threads will step over an instruction
+ # that causes them to exit.
+ gdb_test "break my_exit_syscall if 0"
+
+ # The "breakpoint hitter" thread will repeatedly hit this
+ # breakpoint, causing GDB to stop all threads.
+ gdb_test "break break_here"
+
+ # To avoid flooding the log with thread created/exited messages.
+ gdb_test_no_output "set print thread-events off"
+
+ # Make sure the target reports the breakpoint stops.
+ gdb_test_no_output "set breakpoint condition-evaluation host"
+
+ for { set i 0 } { $i < 30 } { incr i } {
+ with_test_prefix "iter $i" {
+ if { [gdb_test "continue" "hit Breakpoint $::decimal, break_here .*"] != 0 } {
+ # Exit if there's a failure to avoid lengthy timeouts.
+ break
+ }
+ }
+ }
+}
+
+foreach_with_prefix displaced-stepping {off auto} {
+ foreach_with_prefix target-non-stop {off on} {
+ test ${displaced-stepping} ${target-non-stop}
+ }
+}
diff --git a/gdb/testsuite/gdb.threads/step-over-thread-exit.c b/gdb/testsuite/gdb.threads/step-over-thread-exit.c
new file mode 100644
index 00000000000..878e5924c5c
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/step-over-thread-exit.c
@@ -0,0 +1,52 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021-2022 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 <pthread.h>
+#include <assert.h>
+#include <stdlib.h>
+#include "../lib/my-syscalls.h"
+
+static void *
+thread_func (void *arg)
+{
+ my_exit (0);
+
+ /* my_exit above should exit the thread, we don't expect to reach
+ here. */
+ abort ();
+}
+
+int
+main (void)
+{
+ int i;
+
+ /* Spawn and join a thread, 100 times. */
+ for (i = 0; i < 100; i++)
+ {
+ pthread_t thread;
+ int ret;
+
+ ret = pthread_create (&thread, NULL, thread_func, NULL);
+ assert (ret == 0);
+
+ ret = pthread_join (thread, NULL);
+ assert (ret == 0);
+ }
+
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.threads/step-over-thread-exit.exp b/gdb/testsuite/gdb.threads/step-over-thread-exit.exp
new file mode 100644
index 00000000000..ed8534cf518
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/step-over-thread-exit.exp
@@ -0,0 +1,126 @@
+# Copyright 2021-2022 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/>.
+
+# Test stepping over a breakpoint installed on an instruction that
+# exits the thread.
+
+standard_testfile .c
+
+set syscalls_src $srcdir/lib/my-syscalls.S
+
+if { [build_executable "failed to prepare" $testfile \
+ [list $srcfile $syscalls_src] {debug pthreads}] == -1 } {
+ return
+}
+
+# Each argument is a different testing axis, most of them obvious.
+# NS_STOP_ALL is only used if testing "set non-stop on", and indicates
+# whether to have GDB explicitly stop all threads before continuing to
+# thread exit.
+proc test {displaced-stepping non-stop target-non-stop schedlock ns_stop_all} {
+ if {${non-stop} == "off" && $ns_stop_all} {
+ error "invalid arguments"
+ }
+
+ save_vars ::GDBFLAGS {
+ append ::GDBFLAGS " -ex \"maintenance set target-non-stop ${target-non-stop}\""
+ append ::GDBFLAGS " -ex \"set non-stop ${non-stop}\""
+ clean_restart $::binfile
+ }
+
+ gdb_test_no_output "set displaced-stepping ${displaced-stepping}"
+
+ if { ![runto_main] } {
+ return
+ }
+
+ gdb_breakpoint "my_exit_syscall"
+
+ if {$schedlock
+ || (${non-stop} == "on" && $ns_stop_all)} {
+ gdb_test "continue" \
+ "Thread 2 .*hit Breakpoint $::decimal.* my_exit_syscall .*" \
+ "continue until syscall"
+
+ if {${non-stop} == "on"} {
+ # The test only spawns one thread at a time, so this just
+ # stops the main thread.
+ gdb_test_multiple "interrupt -a" "" {
+ -re "$::gdb_prompt " {
+ gdb_test_multiple "" $gdb_test_name {
+ -re "Thread 1 \[^\r\n\]*stopped." {
+ pass $gdb_test_name
+ }
+ }
+ }
+ }
+ }
+
+ gdb_test "thread 2" "Switching to thread 2 .*"
+
+ gdb_test_no_output "set scheduler-locking ${schedlock}"
+
+ gdb_test "continue" \
+ "No unwaited-for children left." \
+ "continue stops when thread exits"
+ } else {
+ gdb_test_no_output "set scheduler-locking ${schedlock}"
+
+ for { set i 0 } { $i < 100 } { incr i } {
+ with_test_prefix "iter $i" {
+ set ok 0
+ set thread "<unknown>"
+ gdb_test_multiple "continue" "" {
+ -re -wrap "Thread ($::decimal) .*hit Breakpoint $::decimal.* my_exit_syscall .*" {
+ set thread $expect_out(1,string)
+ set ok 1
+ }
+ }
+ if {!${ok}} {
+ # Exit if there's a failure to avoid lengthy
+ # timeouts.
+ break
+ }
+
+ if {${non-stop}} {
+ gdb_test "thread $thread" "Switching to thread .*" \
+ "switch to event thread"
+ }
+ }
+ }
+ }
+}
+
+foreach_with_prefix displaced-stepping {off auto} {
+ foreach_with_prefix non-stop {off on} {
+ foreach_with_prefix target-non-stop {off on} {
+ if {${non-stop} == "on" && ${target-non-stop} == "off"} {
+ # Invalid combination.
+ continue
+ }
+
+ foreach_with_prefix schedlock {off on} {
+ if {${non-stop} == "on"} {
+ foreach_with_prefix ns_stop_all {0 1} {
+ test ${displaced-stepping} ${non-stop} ${target-non-stop} \
+ ${schedlock} ${ns_stop_all}
+ }
+ } else {
+ test ${displaced-stepping} ${non-stop} ${target-non-stop} ${schedlock} 0
+ }
+ }
+ }
+ }
+}
diff --git a/gdb/testsuite/lib/my-syscalls.S b/gdb/testsuite/lib/my-syscalls.S
index 6fb53624f31..ff62b5eb4e9 100644
--- a/gdb/testsuite/lib/my-syscalls.S
+++ b/gdb/testsuite/lib/my-syscalls.S
@@ -69,4 +69,8 @@ NAME ## _syscall: ;\

SYSCALL (my_execve, __NR_execve)

+/* void my_exit (int code); */
+
+SYSCALL (my_exit, __NR_exit)
+
.section .note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/lib/my-syscalls.h b/gdb/testsuite/lib/my-syscalls.h
index a0c069c58e5..ceaa587b3e6 100644
--- a/gdb/testsuite/lib/my-syscalls.h
+++ b/gdb/testsuite/lib/my-syscalls.h
@@ -22,4 +22,9 @@

int my_execve (const char *file, char *argv[], char *envp[]);

+/* `exit` syscall, which makes the thread exit (as opposed to
+ `exit_group`, which makes the process exit). */
+
+void my_exit (int code);
+
#endif /* MY_SYSCALLS_H */
--
2.36.0