// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2016 Facebook
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/perf_event.h>
#include <errno.h>
#include <stdbool.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "trace_helpers.h"

#define PRINT_RAW_ADDR 0

/* counts, stackmap */
static int map_fd[2];

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

        if (!addr)
                return;
        sym = ksym_search(addr);
        if (!sym) {
                printf("ksym not found. Is kallsyms loaded?\n");
                return;
        }

        if (PRINT_RAW_ADDR)
                printf("%s/%llx;", sym->name, addr);
        else
                printf("%s;", sym->name);
}

#define TASK_COMM_LEN 16

struct key_t {
        char waker[TASK_COMM_LEN];
        char target[TASK_COMM_LEN];
        __u32 wret;
        __u32 tret;
};

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

        printf("%s;", key->target);
        if (bpf_map_lookup_elem(map_fd[1], &key->tret, 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->wret, ip) != 0) {
                printf("---;");
        } else {
                for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
                        print_ksym(ip[i]);
        }
        printf(";%s %lld\n", key->waker, count);

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

static void print_stacks(int fd)
{
        struct key_t key = {}, next_key;
        __u64 value;

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

static void int_exit(int sig)
{
        print_stacks(map_fd[0]);
        exit(0);
}

int main(int argc, char **argv)
{
        struct bpf_object *obj = NULL;
        struct bpf_link *links[2];
        struct bpf_program *prog;
        int delay = 1, i = 0;
        char filename[256];

        if (load_kallsyms()) {
                printf("failed to process /proc/kallsyms\n");
                return 2;
        }

        snprintf(filename, sizeof(filename), "%s.bpf.o", argv[0]);
        obj = bpf_object__open_file(filename, NULL);
        if (libbpf_get_error(obj)) {
                fprintf(stderr, "ERROR: opening BPF object file failed\n");
                obj = NULL;
                goto cleanup;
        }

        /* load BPF program */
        if (bpf_object__load(obj)) {
                fprintf(stderr, "ERROR: loading BPF object file failed\n");
                goto cleanup;
        }

        map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
        map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
        if (map_fd[0] < 0 || map_fd[1] < 0) {
                fprintf(stderr, "ERROR: finding a map in obj file failed\n");
                goto cleanup;
        }

        signal(SIGINT, int_exit);
        signal(SIGTERM, int_exit);

        bpf_object__for_each_program(prog, obj) {
                links[i] = bpf_program__attach(prog);
                if (libbpf_get_error(links[i])) {
                        fprintf(stderr, "ERROR: bpf_program__attach failed\n");
                        links[i] = NULL;
                        goto cleanup;
                }
                i++;
        }

        if (argc > 1)
                delay = atoi(argv[1]);
        sleep(delay);
        print_stacks(map_fd[0]);

cleanup:
        for (i--; i >= 0; i--)
                bpf_link__destroy(links[i]);

        bpf_object__close(obj);
        return 0;
}