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#include "trace_helpers.h"
  21
  22#define PRINT_RAW_ADDR 0
  23
  24static void print_ksym(__u64 addr)
  25{
  26        struct ksym *sym;
  27
  28        if (!addr)
  29                return;
  30        sym = ksym_search(addr);
  31        if (PRINT_RAW_ADDR)
  32                printf("%s/%llx;", sym->name, addr);
  33        else
  34                printf("%s;", sym->name);
  35}
  36
  37#define TASK_COMM_LEN 16
  38
  39struct key_t {
  40        char waker[TASK_COMM_LEN];
  41        char target[TASK_COMM_LEN];
  42        __u32 wret;
  43        __u32 tret;
  44};
  45
  46static void print_stack(struct key_t *key, __u64 count)
  47{
  48        __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  49        static bool warned;
  50        int i;
  51
  52        printf("%s;", key->target);
  53        if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
  54                printf("---;");
  55        } else {
  56                for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  57                        print_ksym(ip[i]);
  58        }
  59        printf("-;");
  60        if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
  61                printf("---;");
  62        } else {
  63                for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  64                        print_ksym(ip[i]);
  65        }
  66        printf(";%s %lld\n", key->waker, count);
  67
  68        if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  69                printf("stackmap collisions seen. Consider increasing size\n");
  70                warned = true;
  71        } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  72                printf("err stackid %d %d\n", key->tret, key->wret);
  73        }
  74}
  75
  76static void print_stacks(int fd)
  77{
  78        struct key_t key = {}, next_key;
  79        __u64 value;
  80
  81        while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  82                bpf_map_lookup_elem(fd, &next_key, &value);
  83                print_stack(&next_key, value);
  84                key = next_key;
  85        }
  86}
  87
  88static void int_exit(int sig)
  89{
  90        print_stacks(map_fd[0]);
  91        exit(0);
  92}
  93
  94int main(int argc, char **argv)
  95{
  96        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
  97        char filename[256];
  98        int delay = 1;
  99
 100        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 101        setrlimit(RLIMIT_MEMLOCK, &r);
 102
 103        signal(SIGINT, int_exit);
 104        signal(SIGTERM, int_exit);
 105
 106        if (load_kallsyms()) {
 107                printf("failed to process /proc/kallsyms\n");
 108                return 2;
 109        }
 110
 111        if (load_bpf_file(filename)) {
 112                printf("%s", bpf_log_buf);
 113                return 1;
 114        }
 115
 116        if (argc > 1)
 117                delay = atoi(argv[1]);
 118        sleep(delay);
 119        print_stacks(map_fd[0]);
 120
 121        return 0;
 122}
 123