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 #include "trace_helpers.h"
  21
  22 #define PRINT_RAW_ADDR 0
  23
  24 static 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
  44 struct key_t {
  45         char waker[TASK_COMM_LEN];
  46         char target[TASK_COMM_LEN];
  47         __u32 wret;
  48         __u32 tret;
  49 };
  50
  51 static 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
  81 static 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
  93 static void int_exit(int sig)
  94 {
  95         print_stacks(map_fd[0]);
  96         exit(0);
  97 }
  98
  99 int 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 }