xref: /linux/tools/testing/selftests/bpf/prog_tests/exhandler.c (revision 03ab8e6297acd1bc0eedaa050e2a1635c576fd11)
1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2021, Oracle and/or its affiliates. */
3 
4 #include <test_progs.h>
5 
6 /* Test that verifies exception handling is working. fork()
7  * triggers task_newtask tracepoint; that new task will have a
8  * NULL pointer task_works, and the associated task->task_works->func
9  * should not be NULL if task_works itself is non-NULL.
10  *
11  * So to verify exception handling we want to see a NULL task_works
12  * and task_works->func; if we see this we can conclude that the
13  * exception handler ran when we attempted to dereference task->task_works
14  * and zeroed the destination register.
15  */
16 #include "exhandler_kern.skel.h"
17 
test_exhandler(void)18 void test_exhandler(void)
19 {
20 	int err = 0, duration = 0, status;
21 	struct exhandler_kern *skel;
22 	pid_t cpid;
23 
24 	skel = exhandler_kern__open_and_load();
25 	if (CHECK(!skel, "skel_load", "skeleton failed: %d\n", err))
26 		goto cleanup;
27 
28 	skel->bss->test_pid = getpid();
29 
30 	err = exhandler_kern__attach(skel);
31 	if (!ASSERT_OK(err, "attach"))
32 		goto cleanup;
33 	cpid = fork();
34 	if (!ASSERT_GT(cpid, -1, "fork failed"))
35 		goto cleanup;
36 	if (cpid == 0)
37 		_exit(0);
38 	waitpid(cpid, &status, 0);
39 
40 	ASSERT_NEQ(skel->bss->exception_triggered, 0, "verify exceptions occurred");
41 cleanup:
42 	exhandler_kern__destroy(skel);
43 }
44