// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Red Hat, Inc. */
#include <test_progs.h>
#include "fentry_recursive.skel.h"
#include "fentry_recursive_target.skel.h"
#include <bpf/btf.h>
#include "bpf/libbpf_internal.h"

/* Test recursive attachment of tracing progs with more than one nesting level
 * is not possible. Create a chain of attachment, verify that the last prog
 * will fail. Depending on the arguments, following cases are tested:
 *
 * - Recursive loading of tracing progs, without attaching (attach = false,
 *   detach = false). The chain looks like this:
 *       load target
 *       load fentry1 -> target
 *       load fentry2 -> fentry1 (fail)
 *
 * - Recursive attach of tracing progs (attach = true, detach = false). The
 *   chain looks like this:
 *       load target
 *       load fentry1 -> target
 *       attach fentry1 -> target
 *       load fentry2 -> fentry1 (fail)
 *
 * - Recursive attach and detach of tracing progs (attach = true, detach =
 *   true). This validates that attach_tracing_prog flag will be set throughout
 *   the whole lifecycle of an fentry prog, independently from whether it's
 *   detached. The chain looks like this:
 *       load target
 *       load fentry1 -> target
 *       attach fentry1 -> target
 *       detach fentry1
 *       load fentry2 -> fentry1 (fail)
 */
static void test_recursive_fentry_chain(bool attach, bool detach)
{
        struct fentry_recursive_target *target_skel = NULL;
        struct fentry_recursive *tracing_chain[2] = {};
        struct bpf_program *prog;
        int prev_fd, err;

        target_skel = fentry_recursive_target__open_and_load();
        if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
                return;

        /* Create an attachment chain with two fentry progs */
        for (int i = 0; i < 2; i++) {
                tracing_chain[i] = fentry_recursive__open();
                if (!ASSERT_OK_PTR(tracing_chain[i], "fentry_recursive__open"))
                        goto close_prog;

                /* The first prog in the chain is going to be attached to the target
                 * fentry program, the second one to the previous in the chain.
                 */
                prog = tracing_chain[i]->progs.recursive_attach;
                if (i == 0) {
                        prev_fd = bpf_program__fd(target_skel->progs.test1);
                        err = bpf_program__set_attach_target(prog, prev_fd, "test1");
                } else {
                        prev_fd = bpf_program__fd(tracing_chain[i-1]->progs.recursive_attach);
                        err = bpf_program__set_attach_target(prog, prev_fd, "recursive_attach");
                }

                if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
                        goto close_prog;

                err = fentry_recursive__load(tracing_chain[i]);
                /* The first attach should succeed, the second fail */
                if (i == 0) {
                        if (!ASSERT_OK(err, "fentry_recursive__load"))
                                goto close_prog;

                        if (attach) {
                                err = fentry_recursive__attach(tracing_chain[i]);
                                if (!ASSERT_OK(err, "fentry_recursive__attach"))
                                        goto close_prog;
                        }

                        if (detach) {
                                /* Flag attach_tracing_prog should still be set, preventing
                                 * attachment of the following prog.
                                 */
                                fentry_recursive__detach(tracing_chain[i]);
                        }
                } else {
                        if (!ASSERT_ERR(err, "fentry_recursive__load"))
                                goto close_prog;
                }
        }

close_prog:
        fentry_recursive_target__destroy(target_skel);
        for (int i = 0; i < 2; i++) {
                fentry_recursive__destroy(tracing_chain[i]);
        }
}

void test_recursive_fentry(void)
{
        if (test__start_subtest("attach"))
                test_recursive_fentry_chain(true, false);
        if (test__start_subtest("load"))
                test_recursive_fentry_chain(false, false);
        if (test__start_subtest("detach"))
                test_recursive_fentry_chain(true, true);
}

/* Test that a tracing prog reattachment (when we land in
 * "prog->aux->dst_trampoline and tgt_prog is NULL" branch in
 * bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf
 */
void test_fentry_attach_btf_presence(void)
{
        struct fentry_recursive_target *target_skel = NULL;
        struct fentry_recursive *tracing_skel = NULL;
        struct bpf_program *prog;
        int err, link_fd, tgt_prog_fd;

        target_skel = fentry_recursive_target__open_and_load();
        if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
                goto close_prog;

        tracing_skel = fentry_recursive__open();
        if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
                goto close_prog;

        prog = tracing_skel->progs.recursive_attach;
        tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
        err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target");
        if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
                goto close_prog;

        err = fentry_recursive__load(tracing_skel);
        if (!ASSERT_OK(err, "fentry_recursive__load"))
                goto close_prog;

        tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach);
        link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL);
        if (!ASSERT_GE(link_fd, 0, "link_fd"))
                goto close_prog;

        fentry_recursive__detach(tracing_skel);

        err = fentry_recursive__attach(tracing_skel);
        ASSERT_ERR(err, "fentry_recursive__attach");

close_prog:
        fentry_recursive_target__destroy(target_skel);
        fentry_recursive__destroy(tracing_skel);
}

static void *fentry_target_test_run(void *arg)
{
        for (;;) {
                int prog_fd = __atomic_load_n((int *)arg, __ATOMIC_SEQ_CST);
                LIBBPF_OPTS(bpf_test_run_opts, topts);
                int err;

                if (prog_fd == -1)
                        break;
                err = bpf_prog_test_run_opts(prog_fd, &topts);
                if (!ASSERT_OK(err, "fentry_target test_run"))
                        break;
        }

        return NULL;
}

void test_fentry_attach_stress(void)
{
        struct fentry_recursive_target *target_skel = NULL;
        struct fentry_recursive *tracing_skel = NULL;
        struct bpf_program *prog;
        int err, i, tgt_prog_fd;
        pthread_t thread;

        target_skel = fentry_recursive_target__open_and_load();
        if (!ASSERT_OK_PTR(target_skel,
                           "fentry_recursive_target__open_and_load"))
                goto close_prog;
        tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
        err = pthread_create(&thread, NULL,
                             fentry_target_test_run, &tgt_prog_fd);
        if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
                goto close_prog;

        for (i = 0; i < 1000; i++) {
                tracing_skel = fentry_recursive__open();
                if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
                        goto stop_thread;

                prog = tracing_skel->progs.recursive_attach;
                err = bpf_program__set_attach_target(prog, tgt_prog_fd,
                                                     "fentry_target");
                if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
                        goto stop_thread;

                err = fentry_recursive__load(tracing_skel);
                if (!ASSERT_OK(err, "fentry_recursive__load"))
                        goto stop_thread;

                err = fentry_recursive__attach(tracing_skel);
                if (!ASSERT_OK(err, "fentry_recursive__attach"))
                        goto stop_thread;

                fentry_recursive__destroy(tracing_skel);
                tracing_skel = NULL;
        }

stop_thread:
        __atomic_store_n(&tgt_prog_fd, -1, __ATOMIC_SEQ_CST);
        err = pthread_join(thread, NULL);
        ASSERT_OK(err, "pthread_join");
close_prog:
        fentry_recursive__destroy(tracing_skel);
        fentry_recursive_target__destroy(target_skel);
}