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 <bpf/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 (!sym) {
  32                printf("ksym not found. Is kallsyms loaded?\n");
  33                return;
  34        }
  35
  36        if (PRINT_RAW_ADDR)
  37                printf("%s/%llx;", sym->name, addr);
  38        else
  39                printf("%s;", sym->name);
  40}
  41
  42#define TASK_COMM_LEN 16
  43
  44struct key_t {
  45        char waker[TASK_COMM_LEN];
  46        char target[TASK_COMM_LEN];
  47        __u32 wret;
  48        __u32 tret;
  49};
  50
  51static void print_stack(struct key_t *key, __u64 count)
  52{
  53        __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  54        static bool warned;
  55        int i;
  56
  57        printf("%s;", key->target);
  58        if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
  59                printf("---;");
  60        } else {
  61                for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  62                        print_ksym(ip[i]);
  63        }
  64        printf("-;");
  65        if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
  66                printf("---;");
  67        } else {
  68                for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  69                        print_ksym(ip[i]);
  70        }
  71        printf(";%s %lld\n", key->waker, count);
  72
  73        if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  74                printf("stackmap collisions seen. Consider increasing size\n");
  75                warned = true;
  76        } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  77                printf("err stackid %d %d\n", key->tret, key->wret);
  78        }
  79}
  80
  81static void print_stacks(int fd)
  82{
  83        struct key_t key = {}, next_key;
  84        __u64 value;
  85
  86        while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  87                bpf_map_lookup_elem(fd, &next_key, &value);
  88                print_stack(&next_key, value);
  89                key = next_key;
  90        }
  91}
  92
  93static void int_exit(int sig)
  94{
  95        print_stacks(map_fd[0]);
  96        exit(0);
  97}
  98
  99int main(int argc, char **argv)
 100{
 101        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 102        char filename[256];
 103        int delay = 1;
 104
 105        snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 106        setrlimit(RLIMIT_MEMLOCK, &r);
 107
 108        signal(SIGINT, int_exit);
 109        signal(SIGTERM, int_exit);
 110
 111        if (load_kallsyms()) {
 112                printf("failed to process /proc/kallsyms\n");
 113                return 2;
 114        }
 115
 116        if (load_bpf_file(filename)) {
 117                printf("%s", bpf_log_buf);
 118                return 1;
 119        }
 120
 121        if (argc > 1)
 122                delay = atoi(argv[1]);
 123        sleep(delay);
 124        print_stacks(map_fd[0]);
 125
 126        return 0;
 127}
 128