// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */

#include <test_progs.h>
#include "testing_helpers.h"
#include "livepatch_trampoline.skel.h"

static int load_livepatch(void)
{
        char path[4096];

        /* CI will set KBUILD_OUTPUT */
        snprintf(path, sizeof(path), "%s/samples/livepatch/livepatch-sample.ko",
                 getenv("KBUILD_OUTPUT") ? : "../../../..");

        return load_module(path, env_verbosity > VERBOSE_NONE);
}

static void unload_livepatch(void)
{
        /* Disable the livepatch before unloading the module */
        system("echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled");

        unload_module("livepatch_sample", env_verbosity > VERBOSE_NONE);
}

static void read_proc_cmdline(void)
{
        char buf[4096];
        int fd, ret;

        fd = open("/proc/cmdline", O_RDONLY);
        if (!ASSERT_OK_FD(fd, "open /proc/cmdline"))
                return;

        ret = read(fd, buf, sizeof(buf));
        if (!ASSERT_GT(ret, 0, "read /proc/cmdline"))
                goto out;

        ASSERT_OK(strncmp(buf, "this has been live patched", 26), "strncmp");

out:
        close(fd);
}

static void __test_livepatch_trampoline(bool fexit_first)
{
        struct livepatch_trampoline *skel = NULL;
        int err;

        skel = livepatch_trampoline__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
                goto out;

        skel->bss->my_pid = getpid();

        if (!fexit_first) {
                /* fentry program is loaded first by default */
                err = livepatch_trampoline__attach(skel);
                if (!ASSERT_OK(err, "skel_attach"))
                        goto out;
        } else {
                /* Manually load fexit program first. */
                skel->links.fexit_cmdline = bpf_program__attach(skel->progs.fexit_cmdline);
                if (!ASSERT_OK_PTR(skel->links.fexit_cmdline, "attach_fexit"))
                        goto out;

                skel->links.fentry_cmdline = bpf_program__attach(skel->progs.fentry_cmdline);
                if (!ASSERT_OK_PTR(skel->links.fentry_cmdline, "attach_fentry"))
                        goto out;
        }

        read_proc_cmdline();

        ASSERT_EQ(skel->bss->fentry_hit, 1, "fentry_hit");
        ASSERT_EQ(skel->bss->fexit_hit, 1, "fexit_hit");
out:
        livepatch_trampoline__destroy(skel);
}

void test_livepatch_trampoline(void)
{
        int retry_cnt = 0;

retry:
        if (load_livepatch()) {
                if (retry_cnt) {
                        ASSERT_OK(1, "load_livepatch");
                        goto out;
                }
                /*
                 * Something else (previous run of the same test?) loaded
                 * the KLP module. Unload the KLP module and retry.
                 */
                unload_livepatch();
                retry_cnt++;
                goto retry;
        }

        if (test__start_subtest("fentry_first"))
                __test_livepatch_trampoline(false);

        if (test__start_subtest("fexit_first"))
                __test_livepatch_trampoline(true);
out:
        unload_livepatch();
}