samples/bpf/offwaketime_user.c

   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
  23 static 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
  38 struct key_t {
  39         char waker[TASK_COMM_LEN];
  40         char target[TASK_COMM_LEN];
  41         __u32 wret;
  42         __u32 tret;
  43 };
  44
  45 static 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
  75 static 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
  87 static void int_exit(int sig)
  88 {
  89         print_stacks(map_fd[0]);
  90         exit(0);
  91 }
  92
  93 int 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 }