LXR linux/samples/bpf/offwaketime

   1/* Copyright (c) 2016 Facebook
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 */
   7#include <stdio.h>
   8#include <unistd.h>
   9#include <stdlib.h>
  10#include <signal.h>
  11#include <linux/bpf.h>
  12#include <string.h>
  13#include <linux/perf_event.h>
  14#include <errno.h>
  15#include <assert.h>
  16#include <stdbool.h>
  17#include <sys/resource.h>
  18#include "libbpf.h"
  19#include "bpf_load.h"
  20
  21#define PRINT_RAW_ADDR 0
  22
  23static void print_ksym(__u64 addr)
  24{
  25        struct ksym *sym;
  26
  27        if (!addr)
  28                return;
  29        sym = ksym_search(addr);
  30        if (PRINT_RAW_ADDR)
  31                printf("%s/%llx;", sym->name, addr);
  32        else
  33                printf("%s;", sym->name);
  34}
  35
  36#define TASK_COMM_LEN 16
  37
  38struct key_t {
  39        char waker[TASK_COMM_LEN];
  40        char target[TASK_COMM_LEN];
  41        __u32 wret;
  42        __u32 tret;
  43};
  44
  45static void print_stack(struct key_t *key, __u64 count)
  46{
  47        __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  48        static bool warned;
  49        int i;
  50
  51        printf("%s;", key->target);
  52        if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
  53                printf("---;");
  54        } else {
  55                for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  56                        print_ksym(ip[i]);
  57        }
  58        printf("-;");
  59        if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
  60                printf("---;");
  61        } else {
  62                for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  63                        print_ksym(ip[i]);
  64        }
  65        printf(";%s %lld\n", key->waker, count);
  66
  67        if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  68                printf("stackmap collisions seen. Consider increasing size\n");
  69                warned = true;
  70        } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  71                printf("err stackid %d %d\n", key->tret, key->wret);
  72        }
  73}
  74
  75static void print_stacks(int fd)
  76{
  77        struct key_t key = {}, next_key;
  78        __u64 value;
  79
  80        while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  81                bpf_map_lookup_elem(fd, &next_key, &value);
  82                print_stack(&next_key, value);
  83                key = next_key;
  84        }
  85}
  86
  87static void int_exit(int sig)
  88{
  89        print_stacks(map_fd[0]);
  90        exit(0);
  91}
  92
  93int main(int argc, char **argv)
  94{
  95        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
  96        char filename[256];
  97        int delay = 1;
  98
  99        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 100        setrlimit(RLIMIT_MEMLOCK, &r);
 101
 102        signal(SIGINT, int_exit);
 103        signal(SIGTERM, int_exit);
 104
 105        if (load_kallsyms()) {
 106                printf("failed to process /proc/kallsyms\n");
 107                return 2;
 108        }
 109
 110        if (load_bpf_file(filename)) {
 111                printf("%s", bpf_log_buf);
 112                return 1;
 113        }
 114
 115        if (argc > 1)
 116                delay = atoi(argv[1]);
 117        sleep(delay);
 118        print_stacks(map_fd[0]);
 119
 120        return 0;
 121}
 122