livepatch_trampoline.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
  3
  4#include <test_progs.h>
  5#include "testing_helpers.h"
  6#include "livepatch_trampoline.skel.h"
  7
  8static int load_livepatch(void)
  9{
 10	char path[4096];
 11
 12	/* CI will set KBUILD_OUTPUT */
 13	snprintf(path, sizeof(path), "%s/samples/livepatch/livepatch-sample.ko",
 14		 getenv("KBUILD_OUTPUT") ? : "../../../..");
 15
 16	return load_module(path, env_verbosity > VERBOSE_NONE);
 17}
 18
 19static void unload_livepatch(void)
 20{
 21	/* Disable the livepatch before unloading the module */
 22	system("echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled");
 23
 24	unload_module("livepatch_sample", env_verbosity > VERBOSE_NONE);
 25}
 26
 27static void read_proc_cmdline(void)
 28{
 29	char buf[4096];
 30	int fd, ret;
 31
 32	fd = open("/proc/cmdline", O_RDONLY);
 33	if (!ASSERT_OK_FD(fd, "open /proc/cmdline"))
 34		return;
 35
 36	ret = read(fd, buf, sizeof(buf));
 37	if (!ASSERT_GT(ret, 0, "read /proc/cmdline"))
 38		goto out;
 39
 40	ASSERT_OK(strncmp(buf, "this has been live patched", 26), "strncmp");
 41
 42out:
 43	close(fd);
 44}
 45
 46static void __test_livepatch_trampoline(bool fexit_first)
 47{
 48	struct livepatch_trampoline *skel = NULL;
 49	int err;
 50
 51	skel = livepatch_trampoline__open_and_load();
 52	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
 53		goto out;
 54
 55	skel->bss->my_pid = getpid();
 56
 57	if (!fexit_first) {
 58		/* fentry program is loaded first by default */
 59		err = livepatch_trampoline__attach(skel);
 60		if (!ASSERT_OK(err, "skel_attach"))
 61			goto out;
 62	} else {
 63		/* Manually load fexit program first. */
 64		skel->links.fexit_cmdline = bpf_program__attach(skel->progs.fexit_cmdline);
 65		if (!ASSERT_OK_PTR(skel->links.fexit_cmdline, "attach_fexit"))
 66			goto out;
 67
 68		skel->links.fentry_cmdline = bpf_program__attach(skel->progs.fentry_cmdline);
 69		if (!ASSERT_OK_PTR(skel->links.fentry_cmdline, "attach_fentry"))
 70			goto out;
 71	}
 72
 73	read_proc_cmdline();
 74
 75	ASSERT_EQ(skel->bss->fentry_hit, 1, "fentry_hit");
 76	ASSERT_EQ(skel->bss->fexit_hit, 1, "fexit_hit");
 77out:
 78	livepatch_trampoline__destroy(skel);
 79}
 80
 81void test_livepatch_trampoline(void)
 82{
 83	int retry_cnt = 0;
 84
 85retry:
 86	if (load_livepatch()) {
 87		if (retry_cnt) {
 88			ASSERT_OK(1, "load_livepatch");
 89			goto out;
 90		}
 91		/*
 92		 * Something else (previous run of the same test?) loaded
 93		 * the KLP module. Unload the KLP module and retry.
 94		 */
 95		unload_livepatch();
 96		retry_cnt++;
 97		goto retry;
 98	}
 99
100	if (test__start_subtest("fentry_first"))
101		__test_livepatch_trampoline(false);
102
103	if (test__start_subtest("fexit_first"))
104		__test_livepatch_trampoline(true);
105out:
106	unload_livepatch();
107}