/* Copyright (c) 2016 Facebook
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <linux/perf_event.h>
#include <linux/bpf.h>
#include <signal.h>
#include <assert.h>
#include <errno.h>
#include <sys/resource.h>
#include "libbpf.h"
#include "bpf_load.h"
#include "perf-sys.h"

#define SAMPLE_FREQ 50

static bool sys_read_seen, sys_write_seen;

static void print_ksym(__u64 addr)
{
        struct ksym *sym;

        if (!addr)
                return;
        sym = ksym_search(addr);
        printf("%s;", sym->name);
        if (!strcmp(sym->name, "sys_read"))
                sys_read_seen = true;
        else if (!strcmp(sym->name, "sys_write"))
                sys_write_seen = true;
}

static void print_addr(__u64 addr)
{
        if (!addr)
                return;
        printf("%llx;", addr);
}

#define TASK_COMM_LEN 16

struct key_t {
        char comm[TASK_COMM_LEN];
        __u32 kernstack;
        __u32 userstack;
};

static void print_stack(struct key_t *key, __u64 count)
{
        __u64 ip[PERF_MAX_STACK_DEPTH] = {};
        static bool warned;
        int i;

        printf("%3lld %s;", count, key->comm);
        if (bpf_map_lookup_elem(map_fd[1], &key->kernstack, ip) != 0) {
                printf("---;");
        } else {
                for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
                        print_ksym(ip[i]);
        }
        printf("-;");
        if (bpf_map_lookup_elem(map_fd[1], &key->userstack, ip) != 0) {
                printf("---;");
        } else {
                for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
                        print_addr(ip[i]);
        }
        printf("\n");

        if (key->kernstack == -EEXIST && !warned) {
                printf("stackmap collisions seen. Consider increasing size\n");
                warned = true;
        } else if ((int)key->kernstack < 0 && (int)key->userstack < 0) {
                printf("err stackid %d %d\n", key->kernstack, key->userstack);
        }
}

static void int_exit(int sig)
{
        kill(0, SIGKILL);
        exit(0);
}

static void print_stacks(void)
{
        struct key_t key = {}, next_key;
        __u64 value;
        __u32 stackid = 0, next_id;
        int fd = map_fd[0], stack_map = map_fd[1];

        sys_read_seen = sys_write_seen = false;
        while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
                bpf_map_lookup_elem(fd, &next_key, &value);
                print_stack(&next_key, value);
                bpf_map_delete_elem(fd, &next_key);
                key = next_key;
        }

        if (!sys_read_seen || !sys_write_seen) {
                printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
                int_exit(0);
        }

        /* clear stack map */
        while (bpf_map_get_next_key(stack_map, &stackid, &next_id) == 0) {
                bpf_map_delete_elem(stack_map, &next_id);
                stackid = next_id;
        }
}

static void test_perf_event_all_cpu(struct perf_event_attr *attr)
{
        int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
        int *pmu_fd = malloc(nr_cpus * sizeof(int));
        int i;

        /* open perf_event on all cpus */
        for (i = 0; i < nr_cpus; i++) {
                pmu_fd[i] = sys_perf_event_open(attr, -1, i, -1, 0);
                if (pmu_fd[i] < 0) {
                        printf("sys_perf_event_open failed\n");
                        goto all_cpu_err;
                }
                assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
                assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
        }
        system("dd if=/dev/zero of=/dev/null count=5000k");
        print_stacks();
all_cpu_err:
        for (i--; i >= 0; i--)
                close(pmu_fd[i]);
        free(pmu_fd);
}

static void test_perf_event_task(struct perf_event_attr *attr)
{
        int pmu_fd;

        /* open task bound event */
        pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
        if (pmu_fd < 0) {
                printf("sys_perf_event_open failed\n");
                return;
        }
        assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
        assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0) == 0);
        system("dd if=/dev/zero of=/dev/null count=5000k");
        print_stacks();
        close(pmu_fd);
}

static void test_bpf_perf_event(void)
{
        struct perf_event_attr attr_type_hw = {
                .sample_freq = SAMPLE_FREQ,
                .freq = 1,
                .type = PERF_TYPE_HARDWARE,
                .config = PERF_COUNT_HW_CPU_CYCLES,
                .inherit = 1,
        };
        struct perf_event_attr attr_type_sw = {
                .sample_freq = SAMPLE_FREQ,
                .freq = 1,
                .type = PERF_TYPE_SOFTWARE,
                .config = PERF_COUNT_SW_CPU_CLOCK,
                .inherit = 1,
        };

        test_perf_event_all_cpu(&attr_type_hw);
        test_perf_event_task(&attr_type_hw);
        test_perf_event_all_cpu(&attr_type_sw);
        test_perf_event_task(&attr_type_sw);
}


int main(int argc, char **argv)
{
        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
        char filename[256];

        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
        setrlimit(RLIMIT_MEMLOCK, &r);

        signal(SIGINT, int_exit);

        if (load_kallsyms()) {
                printf("failed to process /proc/kallsyms\n");
                return 1;
        }

        if (load_bpf_file(filename)) {
                printf("%s", bpf_log_buf);
                return 2;
        }

        if (fork() == 0) {
                read_trace_pipe();
                return 0;
        }
        test_bpf_perf_event();

        int_exit(0);
        return 0;
}