tracing/user_events: Add ABI self-test

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.

Link: https://lkml.kernel.org/r/20230328235219.203-8-beaub@linux.microsoft.com
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/tools/testing/selftests/user_events/Makefile b/tools/testing/selftests/user_events/Makefile
index 6b512b8..9e95bd4 100644 (file)
--- a/tools/testing/selftests/user_events/Makefile
+++ b/tools/testing/selftests/user_events/Makefile
@@ -10,7 +10,7 @@ LDLIBS += -lrt -lpthread -lm
 # This test will not compile until user_events.h is added
 # back to uapi.
 
-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 (file)
index 0000000..e0323d3
--- /dev/null
+++ b/tools/testing/selftests/user_events/abi_test.c
@@ -0,0 +1,226 @@
+// 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);
+}