[PATCH v5 07/11] tracing/user_events: Add ABI self-test

Beau Belgrave
2022-12-05T21:00:53Z

Add ABI specific self-test to ensure enablements work in various
scenarios such as fork, VM_CLONE, and basic event enable/disable.
Ensure ABI contracts/limits are also being upheld, such as bit limits
and data size limits.

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
---
tools/testing/selftests/user_events/Makefile | 2 +-
.../testing/selftests/user_events/abi_test.c | 228 ++++++++++++++++++
2 files changed, 229 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/user_events/abi_test.c

diff --git a/tools/testing/selftests/user_events/Makefile b/tools/testing/selftests/user_events/Makefile
index c765d8635d9a..d5f64ef93197 100644
--- a/tools/testing/selftests/user_events/Makefile
+++ b/tools/testing/selftests/user_events/Makefile
@@ -2,7 +2,7 @@
CFLAGS += -Wl,-no-as-needed -Wall -I../../../../usr/include
LDLIBS += -lrt -lpthread -lm

-TEST_GEN_PROGS = ftrace_test dyn_test perf_test
+TEST_GEN_PROGS = ftrace_test dyn_test perf_test abi_test

TEST_FILES := settings

diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c
new file mode 100644
index 000000000000..aab387af2a66
--- /dev/null
+++ b/tools/testing/selftests/user_events/abi_test.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * User Events ABI Test Program
+ *
+ * Copyright (c) 2022 Beau Belgrave <beaub@linux.microsoft.com>
+ */
+
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <errno.h>
+#include <linux/user_events.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+
+#include "../kselftest_harness.h"
+
+const char *data_file = "/sys/kernel/tracing/user_events_data";
+const char *enable_file = "/sys/kernel/tracing/events/user_events/__abi_event/enable";
+
+static int change_event(bool enable)
+{
+ int fd = open(enable_file, O_RDWR);
+ int ret;
+
+ if (fd < 0)
+ return -1;
+
+ if (enable)
+ ret = write(fd, "1", 1);
+ else
+ ret = write(fd, "0", 1);
+
+ close(fd);
+
+ if (ret == 1)
+ ret = 0;
+ else
+ ret = -1;
+
+ return ret;
+}
+
+static int reg_enable(long *enable, int size, int bit)
+{
+ struct user_reg reg = {0};
+ int fd = open(data_file, O_RDWR);
+ int ret;
+
+ if (fd < 0)
+ return -1;
+
+ reg.size = sizeof(reg);
+ reg.name_args = (__u64)"__abi_event";
+ reg.enable_bit = bit;
+ reg.enable_addr = (__u64)enable;
+ reg.enable_size = size;
+
+ ret = ioctl(fd, DIAG_IOCSREG, &reg);
+
+ close(fd);
+
+ return ret;
+}
+
+static int reg_disable(long *enable, int bit)
+{
+ struct user_unreg reg = {0};
+ int fd = open(data_file, O_RDWR);
+ int ret;
+
+ if (fd < 0)
+ return -1;
+
+ reg.size = sizeof(reg);
+ reg.disable_bit = bit;
+ reg.disable_addr = (__u64)enable;
+
+ ret = ioctl(fd, DIAG_IOCSUNREG, &reg);
+
+ close(fd);
+
+ return ret;
+}
+
+FIXTURE(user) {
+ long check;
+};
+
+FIXTURE_SETUP(user) {
+ change_event(false);
+ self->check = 0;
+}
+
+FIXTURE_TEARDOWN(user) {
+}
+
+TEST_F(user, enablement) {
+ /* Changes should be reflected immediately */
+ ASSERT_EQ(0, self->check);
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 0));
+ ASSERT_EQ(0, change_event(true));
+ ASSERT_EQ(1, self->check);
+ ASSERT_EQ(0, change_event(false));
+ ASSERT_EQ(0, self->check);
+
+ /* Should not change after disable */
+ ASSERT_EQ(0, change_event(true));
+ ASSERT_EQ(1, self->check);
+ ASSERT_EQ(0, reg_disable(&self->check, 0));
+ ASSERT_EQ(0, change_event(false));
+ ASSERT_EQ(1, self->check);
+ self->check = 0;
+}
+
+TEST_F(user, bit_sizes) {
+ /* Allow 0-31 bits for 32-bit */
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 0));
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 31));
+ ASSERT_NE(0, reg_enable(&self->check, sizeof(int), 32));
+ ASSERT_EQ(0, reg_disable(&self->check, 0));
+ ASSERT_EQ(0, reg_disable(&self->check, 31));
+
+#if BITS_PER_LONG == 8
+ /* Allow 0-64 bits for 64-bit */
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(long), 63));
+ ASSERT_NE(0, reg_enable(&self->check, sizeof(long), 64));
+ ASSERT_EQ(0, reg_disable(&self->check, 63));
+#endif
+
+ /* Disallowed sizes (everything beside 4 and 8) */
+ ASSERT_NE(0, reg_enable(&self->check, 1, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 2, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 3, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 5, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 6, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 7, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 9, 0));
+ ASSERT_NE(0, reg_enable(&self->check, 128, 0));
+}
+
+TEST_F(user, forks) {
+ int i;
+
+ /* Ensure COW pages get updated after fork */
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 0));
+ ASSERT_EQ(0, self->check);
+
+ if (fork() == 0) {
+ /* Force COW */
+ self->check = 0;
+
+ /* Up to 1 sec for enablement */
+ for (i=0; i<10; ++i) {
+ usleep(100000);
+
+ if (self->check)
+ exit(0);
+ }
+
+ exit(1);
+ }
+
+ /* Allow generous time for COW, then enable */
+ usleep(100000);
+ ASSERT_EQ(0, change_event(true));
+
+ ASSERT_NE(-1, wait(&i));
+ ASSERT_EQ(0, WEXITSTATUS(i));
+
+ /* Ensure child doesn't disable parent */
+ if (fork() == 0) {
+ exit(reg_disable(&self->check, 0));
+ }
+
+ ASSERT_NE(-1, wait(&i));
+ ASSERT_EQ(0, WEXITSTATUS(i));
+ ASSERT_EQ(1, self->check);
+ ASSERT_EQ(0, change_event(false));
+ ASSERT_EQ(0, self->check);
+}
+
+/* Waits up to 1 sec for enablement */
+static int clone_check(void *check)
+{
+ int i;
+
+ for (i=0; i<10; ++i) {
+ usleep(100000);
+
+ if (*(long *)check) {
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+TEST_F(user, clones) {
+ int i, stack_size = 4096;
+ void *stack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK,
+ -1, 0);
+
+ ASSERT_NE(MAP_FAILED, stack);
+ ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 0));
+ ASSERT_EQ(0, self->check);
+
+ /* Shared VM should see enablements */
+ ASSERT_NE(-1, clone(&clone_check, stack + stack_size,
+ CLONE_VM | SIGCHLD, &self->check));
+
+ ASSERT_EQ(0, change_event(true));
+ ASSERT_NE(-1, wait(&i));
+ ASSERT_EQ(0, WEXITSTATUS(i));
+ munmap(stack, stack_size);
+ ASSERT_EQ(0, change_event(false));
+}
+
+int main(int argc, char **argv)
+{
+ return test_harness_run(argc, argv);
+}
--
2.25.1