selftests/user_events: Test persist flag cases

Now that we have exposed USER_EVENT_REG_PERSIST events can persist both
via the ABI and in the /sys/kernel/tracing/dynamic_events file.

Ensure both the ABI and DYN cases work by calling both during the parse
tests. Add new flags test that ensures only USER_EVENT_REG_PERSIST is
honored and any other flag is invalid.

Link: https://lkml.kernel.org/r/20230912180704.1284-3-beaub@linux.microsoft.com

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/testing/selftests/user_events/abi_test.c

@@ -24,6 +24,18 @@
 const char *data_file = "/sys/kernel/tracing/user_events_data";
 const char *enable_file = "/sys/kernel/tracing/events/user_events/__abi_event/enable";
 
+static bool event_exists(void)
+{
+	int fd = open(enable_file, O_RDWR);
+
+	if (fd < 0)
+		return false;
+
+	close(fd);
+
+	return true;
+}
+
 static int change_event(bool enable)
 {
 	int fd = open(enable_file, O_RDWR);
@@ -47,7 +59,22 @@ static int change_event(bool enable)
 	return ret;
 }
 
-static int reg_enable(long *enable, int size, int bit)
+static int event_delete(void)
+{
+	int fd = open(data_file, O_RDWR);
+	int ret;
+
+	if (fd < 0)
+		return -1;
+
+	ret = ioctl(fd, DIAG_IOCSDEL, "__abi_event");
+
+	close(fd);
+
+	return ret;
+}
+
+static int reg_enable_flags(long *enable, int size, int bit, int flags)
 {
 	struct user_reg reg = {0};
 	int fd = open(data_file, O_RDWR);
@@ -58,6 +85,7 @@ static int reg_enable(long *enable, int size, int bit)
 
 	reg.size = sizeof(reg);
 	reg.name_args = (__u64)"__abi_event";
+	reg.flags = flags;
 	reg.enable_bit = bit;
 	reg.enable_addr = (__u64)enable;
 	reg.enable_size = size;
@@ -69,6 +97,11 @@ static int reg_enable(long *enable, int size, int bit)
 	return ret;
 }
 
+static int reg_enable(long *enable, int size, int bit)
+{
+	return reg_enable_flags(enable, size, bit, 0);
+}
+
 static int reg_disable(long *enable, int bit)
 {
 	struct user_unreg reg = {0};
@@ -126,6 +159,26 @@ TEST_F(user, enablement) {
 	ASSERT_EQ(0, change_event(false));
 }
 
+TEST_F(user, flags) {
+	/* USER_EVENT_REG_PERSIST is allowed */
+	ASSERT_EQ(0, reg_enable_flags(&self->check, sizeof(int), 0,
+				      USER_EVENT_REG_PERSIST));
+	ASSERT_EQ(0, reg_disable(&self->check, 0));
+
+	/* Ensure it exists after close and disable */
+	ASSERT_TRUE(event_exists());
+
+	/* Ensure we can delete it */
+	ASSERT_EQ(0, event_delete());
+
+	/* USER_EVENT_REG_MAX or above is not allowed */
+	ASSERT_EQ(-1, reg_enable_flags(&self->check, sizeof(int), 0,
+				       USER_EVENT_REG_MAX));
+
+	/* Ensure it does not exist after invalid flags */
+	ASSERT_FALSE(event_exists());
+}
+
 TEST_F(user, bit_sizes) {
 	/* Allow 0-31 bits for 32-bit */
 	ASSERT_EQ(0, reg_enable(&self->check, sizeof(int), 0));

tools/testing/selftests/user_events/dyn_test.c

@@ -17,9 +17,25 @@
 #include "../kselftest_harness.h"
 #include "user_events_selftests.h"
 
+const char *dyn_file = "/sys/kernel/tracing/dynamic_events";
 const char *abi_file = "/sys/kernel/tracing/user_events_data";
 const char *enable_file = "/sys/kernel/tracing/events/user_events/__test_event/enable";
 
+static int event_delete(void)
+{
+	int fd = open(abi_file, O_RDWR);
+	int ret;
+
+	if (fd < 0)
+		return -1;
+
+	ret = ioctl(fd, DIAG_IOCSDEL, "__test_event");
+
+	close(fd);
+
+	return ret;
+}
+
 static bool wait_for_delete(void)
 {
 	int i;
@@ -64,7 +80,31 @@ static int unreg_event(int fd, int *check, int bit)
 	return ioctl(fd, DIAG_IOCSUNREG, &unreg);
 }
 
-static int parse(int *check, const char *value)
+static int parse_dyn(const char *value)
+{
+	int fd = open(dyn_file, O_RDWR | O_APPEND);
+	int len = strlen(value);
+	int ret;
+
+	if (fd == -1)
+		return -1;
+
+	ret = write(fd, value, len);
+
+	if (ret == len)
+		ret = 0;
+	else
+		ret = -1;
+
+	close(fd);
+
+	if (ret == 0)
+		event_delete();
+
+	return ret;
+}
+
+static int parse_abi(int *check, const char *value)
 {
 	int fd = open(abi_file, O_RDWR);
 	int ret;
@@ -90,6 +130,18 @@ static int parse(int *check, const char *value)
 	return ret;
 }
 
+static int parse(int *check, const char *value)
+{
+	int abi_ret = parse_abi(check, value);
+	int dyn_ret = parse_dyn(value);
+
+	/* Ensure both ABI and DYN parse the same way */
+	if (dyn_ret != abi_ret)
+		return -1;
+
+	return dyn_ret;
+}
+
 static int check_match(int *check, const char *first, const char *second, bool *match)
 {
 	int fd = open(abi_file, O_RDWR);