[PATCH] selftests: breakpoint: add step_after_suspend_test

Greg Hackmann
2016-02-22T18:11:38Z

Commit e56d82a11617 ("arm64: cpu hotplug: ensure we mask out
CPU_TASKS_FROZEN in notifiers") fixed a long-standing ARM64 bug that
broke single-stepping after a suspend/resume cycle. Add a kernel
selftest to make sure this doesn't regress or affect other platforms.

Signed-off-by: Greg Hackmann <ghackmann@google.com>
---
tools/testing/selftests/breakpoints/Makefile | 4 +-
.../breakpoints/step_after_suspend_test.c | 219 +++++++++++++++++++++
2 files changed, 222 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/breakpoints/step_after_suspend_test.c

diff --git a/tools/testing/selftests/breakpoints/Makefile b/tools/testing/selftests/breakpoints/Makefile
index c0d9570..74e533f 100644
--- a/tools/testing/selftests/breakpoints/Makefile
+++ b/tools/testing/selftests/breakpoints/Makefile
@@ -6,9 +6,11 @@ ifeq ($(ARCH),x86)
TEST_PROGS := breakpoint_test
endif

+TEST_PROGS += step_after_suspend_test
+
all: $(TEST_PROGS)

include ../lib.mk

clean:
- rm -fr breakpoint_test
+ rm -fr breakpoint_test step_after_suspend_test
diff --git a/tools/testing/selftests/breakpoints/step_after_suspend_test.c b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
new file mode 100644
index 0000000..93dfdec
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ptrace.h>
+#include <sys/stat.h>
+#include <sys/timerfd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
+
+void child(int cpu)
+{
+ cpu_set_t set;
+
+ CPU_ZERO(&set);
+ CPU_SET(cpu, &set);
+ if (sched_setaffinity(0, sizeof(set), &set) != 0) {
+ perror("sched_setaffinity() failed");
+ _exit(1);
+ }
+
+ if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+ perror("ptrace(PTRACE_TRACEME) failed");
+ _exit(1);
+ }
+
+ if (raise(SIGSTOP) != 0) {
+ perror("raise(SIGSTOP) failed");
+ _exit(1);
+ }
+
+ _exit(0);
+}
+
+bool run_test(int cpu)
+{
+ int status;
+ pid_t pid = fork();
+ pid_t wpid;
+
+ if (pid < 0) {
+ perror("fork() failed");
+ return false;
+ }
+ if (pid == 0)
+ child(cpu);
+
+ wpid = waitpid(pid, &status, __WALL);
+ if (wpid != pid) {
+ perror("waitpid() failed");
+ return false;
+ }
+ if (!WIFSTOPPED(status)) {
+ printf("child did not stop\n");
+ return false;
+ }
+ if (WSTOPSIG(status) != SIGSTOP) {
+ printf("child did not stop with SIGSTOP\n");
+ return false;
+ }
+
+ if (ptrace(PTRACE_SINGLESTEP, pid, NULL, NULL) < 0) {
+ if (errno == EIO) {
+ printf("ptrace(PTRACE_SINGLESTEP) not supported on this architecture\n");
+ ksft_exit_skip();
+ }
+ perror("ptrace(PTRACE_SINGLESTEP) failed");
+ return false;
+ }
+
+ wpid = waitpid(pid, &status, __WALL);
+ if (wpid != pid) {
+ perror("waitpid() failed");
+ return false;
+ }
+ if (WIFEXITED(status)) {
+ printf("child did not single-step\n");
+ return false;
+ }
+ if (!WIFSTOPPED(status)) {
+ printf("child did not stop\n");
+ return false;
+ }
+ if (WSTOPSIG(status) != SIGTRAP) {
+ printf("child did not stop with SIGTRAP\n");
+ return false;
+ }
+
+ if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+ perror("ptrace(PTRACE_CONT) failed");
+ return false;
+ }
+
+ wpid = waitpid(pid, &status, __WALL);
+ if (wpid != pid) {
+ perror("waitpid() failed");
+ return false;
+ }
+ if (!WIFEXITED(status)) {
+ printf("child did not exit after PTRACE_CONT\n");
+ return false;
+ }
+
+ return true;
+}
+
+void suspend(void)
+{
+ int power_state_fd;
+ struct sigevent event = {};
+ int timerfd;
+ int err;
+ struct itimerspec spec = {};
+
+ power_state_fd = open("/sys/power/state", O_RDWR);
+ if (power_state_fd < 0) {
+ perror("open(\"/sys/power/state\") failed (is this test running as root?)");
+ ksft_exit_fail();
+ }
+
+ timerfd = timerfd_create(CLOCK_BOOTTIME_ALARM, 0);
+ if (timerfd < 0) {
+ perror("timerfd_create() failed");
+ ksft_exit_fail();
+ }
+
+ spec.it_value.tv_sec = 5;
+ err = timerfd_settime(timerfd, 0, &spec, NULL);
+ if (err < 0) {
+ perror("timerfd_settime() failed");
+ ksft_exit_fail();
+ }
+
+ if (write(power_state_fd, "mem", strlen("mem")) != strlen("mem")) {
+ perror("entering suspend failed");
+ ksft_exit_fail();
+ }
+
+ close(timerfd);
+ close(power_state_fd);
+}
+
+int main(int argc, char **argv)
+{
+ int opt;
+ bool do_suspend = true;
+ bool succeeded = true;
+ cpu_set_t available_cpus;
+ int err;
+ int cpu;
+
+ while ((opt = getopt(argc, argv, "n")) != -1) {
+ switch (opt) {
+ case 'n':
+ do_suspend = false;
+ break;
+ default:
+ printf("Usage: %s [-n]\n", argv[0]);
+ printf(" -n: do not trigger a suspend/resume cycle before the test\n");
+ return -1;
+ }
+ }
+
+ if (do_suspend)
+ suspend();
+
+ err = sched_getaffinity(0, sizeof(available_cpus), &available_cpus);
+ if (err < 0) {
+ perror("sched_getaffinity() failed");
+ ksft_exit_fail();
+ }
+
+ for (cpu = 0; cpu < CPU_SETSIZE; cpu++) {
+ bool test_success;
+
+ if (!CPU_ISSET(cpu, &available_cpus))
+ continue;
+
+ test_success = run_test(cpu);
+ printf("CPU %d: ", cpu);
+ if (test_success) {
+ printf("[OK]\n");
+ ksft_inc_pass_cnt();
+ } else {
+ printf("[FAILED]\n");
+ ksft_inc_fail_cnt();
+ succeeded = false;
+ }
+ }
+
+ ksft_print_cnts();
+ if (succeeded)
+ ksft_exit_pass();
+ else
+ ksft_exit_fail();
+}
+
--
2.7.0.rc3.207.g0ac5344