// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#define _GNU_SOURCE
#include <linux/compiler.h>
#include <test_progs.h>
#include "testing_helpers.h"
#include "test_perf_link.skel.h"

#define BURN_TIMEOUT_MS 100
#define BURN_TIMEOUT_NS BURN_TIMEOUT_MS * 1000000

static void burn_cpu(void)
{
        int i;

        /* spin the loop for a while (random high number) */
        for (i = 0; i < 1000000; ++i)
                barrier();
}

void test_perf_link(void)
{
        struct test_perf_link *skel = NULL;
        struct perf_event_attr attr;
        int pfd = -1, link_fd = -1, err;
        int run_cnt_before, run_cnt_after;
        struct bpf_link_info info;
        __u32 info_len = sizeof(info);
        __u64 timeout_time_ns;

        /* create perf event */
        memset(&attr, 0, sizeof(attr));
        attr.size = sizeof(attr);
        attr.type = PERF_TYPE_SOFTWARE;
        attr.config = PERF_COUNT_SW_CPU_CLOCK;
        attr.freq = 1;
        attr.sample_freq = 1000;
        pfd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);
        if (!ASSERT_GE(pfd, 0, "perf_fd"))
                goto cleanup;

        skel = test_perf_link__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_load"))
                goto cleanup;

        link_fd = bpf_link_create(bpf_program__fd(skel->progs.handler), pfd,
                                  BPF_PERF_EVENT, NULL);
        if (!ASSERT_GE(link_fd, 0, "link_fd"))
                goto cleanup;

        memset(&info, 0, sizeof(info));
        err = bpf_link_get_info_by_fd(link_fd, &info, &info_len);
        if (!ASSERT_OK(err, "link_get_info"))
                goto cleanup;

        ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "link_type");
        ASSERT_GT(info.id, 0, "link_id");
        ASSERT_GT(info.prog_id, 0, "link_prog_id");

        /* ensure we get at least one perf_event prog execution */
        timeout_time_ns = get_time_ns() + BURN_TIMEOUT_NS;
        while (true) {
                burn_cpu();
                if (skel->bss->run_cnt > 0)
                        break;
                if (!ASSERT_LT(get_time_ns(), timeout_time_ns, "run_cnt_timeout"))
                        break;
        }

        /* perf_event is still active, but we close link and BPF program
         * shouldn't be executed anymore
         */
        close(link_fd);
        link_fd = -1;

        /* make sure there are no stragglers */
        kern_sync_rcu();

        run_cnt_before = skel->bss->run_cnt;
        burn_cpu();
        run_cnt_after = skel->bss->run_cnt;

        ASSERT_EQ(run_cnt_before, run_cnt_after, "run_cnt_before_after");

cleanup:
        if (link_fd >= 0)
                close(link_fd);
        if (pfd >= 0)
                close(pfd);
        test_perf_link__destroy(skel);
}