Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
8#define LIVEPATCH_ENABLED_PATH "/sys/kernel/livepatch/livepatch_sample/enabled"
9
10static int load_livepatch(void)
11{
12 char path[4096];
13
14 /* CI will set KBUILD_OUTPUT */
15 snprintf(path, sizeof(path), "%s/samples/livepatch/livepatch-sample.ko",
16 getenv("KBUILD_OUTPUT") ? : "../../../..");
17
18 return load_module(path, env_verbosity > VERBOSE_NONE);
19}
20
21static void unload_livepatch(void)
22{
23 /* Disable the livepatch before unloading the module */
24 if (!access(LIVEPATCH_ENABLED_PATH, F_OK))
25 system("echo 0 > " LIVEPATCH_ENABLED_PATH);
26
27 unload_module("livepatch_sample", env_verbosity > VERBOSE_NONE);
28}
29
30static void read_proc_cmdline(void)
31{
32 char buf[4096];
33 int fd, ret;
34
35 fd = open("/proc/cmdline", O_RDONLY);
36 if (!ASSERT_OK_FD(fd, "open /proc/cmdline"))
37 return;
38
39 ret = read(fd, buf, sizeof(buf));
40 if (!ASSERT_GT(ret, 0, "read /proc/cmdline"))
41 goto out;
42
43 ASSERT_OK(strncmp(buf, "this has been live patched", 26), "strncmp");
44
45out:
46 close(fd);
47}
48
49static void __test_livepatch_trampoline(bool fexit_first)
50{
51 struct livepatch_trampoline *skel = NULL;
52 int err;
53
54 skel = livepatch_trampoline__open_and_load();
55 if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
56 goto out;
57
58 skel->bss->my_pid = getpid();
59
60 if (!fexit_first) {
61 /* fentry program is loaded first by default */
62 err = livepatch_trampoline__attach(skel);
63 if (!ASSERT_OK(err, "skel_attach"))
64 goto out;
65 } else {
66 /* Manually load fexit program first. */
67 skel->links.fexit_cmdline = bpf_program__attach(skel->progs.fexit_cmdline);
68 if (!ASSERT_OK_PTR(skel->links.fexit_cmdline, "attach_fexit"))
69 goto out;
70
71 skel->links.fentry_cmdline = bpf_program__attach(skel->progs.fentry_cmdline);
72 if (!ASSERT_OK_PTR(skel->links.fentry_cmdline, "attach_fentry"))
73 goto out;
74 }
75
76 read_proc_cmdline();
77
78 ASSERT_EQ(skel->bss->fentry_hit, 1, "fentry_hit");
79 ASSERT_EQ(skel->bss->fexit_hit, 1, "fexit_hit");
80out:
81 livepatch_trampoline__destroy(skel);
82}
83
84void test_livepatch_trampoline(void)
85{
86 int retry_cnt = 0;
87 int err;
88
89 /* Skip if kernel was built without CONFIG_LIVEPATCH */
90 if (access("/sys/kernel/livepatch", F_OK)) {
91 test__skip();
92 return;
93 }
94
95retry:
96 err = load_livepatch();
97 if (err) {
98 if (err == -ENOENT) {
99 test__skip();
100 return;
101 }
102
103 if (retry_cnt) {
104 ASSERT_OK(1, "load_livepatch");
105 goto out;
106 }
107 /*
108 * Something else (previous run of the same test?) loaded
109 * the KLP module. Unload the KLP module and retry.
110 */
111 unload_livepatch();
112 retry_cnt++;
113 goto retry;
114 }
115
116 if (test__start_subtest("fentry_first"))
117 __test_livepatch_trampoline(false);
118
119 if (test__start_subtest("fexit_first"))
120 __test_livepatch_trampoline(true);
121out:
122 unload_livepatch();
123}