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

Andrew Burgess via Gdb-patches
2023-06-12T09:54:23Z

Pedro Alves <pedro@palves.net> writes:

> 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.

LGTM.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>

Thanks,
Andrew

>
> 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