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Both livepatch and BPF trampoline use ftrace. Special attention is needed
when livepatch and fexit program touch the same function at the same
time, because livepatch updates a kernel function and the BPF trampoline
need to call into the right version of the kernel function.
Use samples/livepatch/livepatch-sample.ko for the test.
The test covers two cases:
1) When a fentry program is loaded first. This exercises the
modify_ftrace_direct code path.
2) When a fentry program is loaded first. This exercises the
register_ftrace_direct code path.
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20251027175023.1521602-4-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
108 lines
2.5 KiB
C
108 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
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#include <test_progs.h>
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#include "testing_helpers.h"
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#include "livepatch_trampoline.skel.h"
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static int load_livepatch(void)
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{
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char path[4096];
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/* CI will set KBUILD_OUTPUT */
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snprintf(path, sizeof(path), "%s/samples/livepatch/livepatch-sample.ko",
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getenv("KBUILD_OUTPUT") ? : "../../../..");
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return load_module(path, env_verbosity > VERBOSE_NONE);
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}
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static void unload_livepatch(void)
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{
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/* Disable the livepatch before unloading the module */
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system("echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled");
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unload_module("livepatch_sample", env_verbosity > VERBOSE_NONE);
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}
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static void read_proc_cmdline(void)
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{
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char buf[4096];
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int fd, ret;
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fd = open("/proc/cmdline", O_RDONLY);
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if (!ASSERT_OK_FD(fd, "open /proc/cmdline"))
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return;
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ret = read(fd, buf, sizeof(buf));
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if (!ASSERT_GT(ret, 0, "read /proc/cmdline"))
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goto out;
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ASSERT_OK(strncmp(buf, "this has been live patched", 26), "strncmp");
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out:
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close(fd);
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}
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static void __test_livepatch_trampoline(bool fexit_first)
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{
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struct livepatch_trampoline *skel = NULL;
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int err;
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skel = livepatch_trampoline__open_and_load();
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if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
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goto out;
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skel->bss->my_pid = getpid();
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if (!fexit_first) {
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/* fentry program is loaded first by default */
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err = livepatch_trampoline__attach(skel);
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if (!ASSERT_OK(err, "skel_attach"))
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goto out;
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} else {
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/* Manually load fexit program first. */
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skel->links.fexit_cmdline = bpf_program__attach(skel->progs.fexit_cmdline);
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if (!ASSERT_OK_PTR(skel->links.fexit_cmdline, "attach_fexit"))
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goto out;
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skel->links.fentry_cmdline = bpf_program__attach(skel->progs.fentry_cmdline);
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if (!ASSERT_OK_PTR(skel->links.fentry_cmdline, "attach_fentry"))
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goto out;
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}
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read_proc_cmdline();
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ASSERT_EQ(skel->bss->fentry_hit, 1, "fentry_hit");
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ASSERT_EQ(skel->bss->fexit_hit, 1, "fexit_hit");
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out:
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livepatch_trampoline__destroy(skel);
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}
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void test_livepatch_trampoline(void)
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{
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int retry_cnt = 0;
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retry:
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if (load_livepatch()) {
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if (retry_cnt) {
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ASSERT_OK(1, "load_livepatch");
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goto out;
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}
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/*
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* Something else (previous run of the same test?) loaded
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* the KLP module. Unload the KLP module and retry.
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*/
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unload_livepatch();
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retry_cnt++;
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goto retry;
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}
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if (test__start_subtest("fentry_first"))
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__test_livepatch_trampoline(false);
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if (test__start_subtest("fexit_first"))
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__test_livepatch_trampoline(true);
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out:
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unload_livepatch();
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}
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