root/samples/bpf/offwaketime_user.c

DEFINITIONS

1. print_ksym
2. print_stack
3. print_stacks
4. int_exit
5. main

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2016 Facebook
   3  */
   4 #include <stdio.h>
   5 #include <unistd.h>
   6 #include <stdlib.h>
   7 #include <signal.h>
   8 #include <linux/bpf.h>
   9 #include <string.h>
  10 #include <linux/perf_event.h>
  11 #include <errno.h>
  12 #include <assert.h>
  13 #include <stdbool.h>
  14 #include <sys/resource.h>
  15 #include "libbpf.h"
  16 #include "bpf_load.h"
  17 #include "trace_helpers.h"
  18 
  19 #define PRINT_RAW_ADDR 0
  20 
  21 static void print_ksym(__u64 addr)
  22 {
  23         struct ksym *sym;
  24 
  25         if (!addr)
  26                 return;
  27         sym = ksym_search(addr);
  28         if (!sym) {
  29                 printf("ksym not found. Is kallsyms loaded?\n");
  30                 return;
  31         }
  32 
  33         if (PRINT_RAW_ADDR)
  34                 printf("%s/%llx;", sym->name, addr);
  35         else
  36                 printf("%s;", sym->name);
  37 }
  38 
  39 #define TASK_COMM_LEN 16
  40 
  41 struct key_t {
  42         char waker[TASK_COMM_LEN];
  43         char target[TASK_COMM_LEN];
  44         __u32 wret;
  45         __u32 tret;
  46 };
  47 
  48 static void print_stack(struct key_t *key, __u64 count)
  49 {
  50         __u64 ip[PERF_MAX_STACK_DEPTH] = {};
  51         static bool warned;
  52         int i;
  53 
  54         printf("%s;", key->target);
  55         if (bpf_map_lookup_elem(map_fd[3], &key->tret, ip) != 0) {
  56                 printf("---;");
  57         } else {
  58                 for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
  59                         print_ksym(ip[i]);
  60         }
  61         printf("-;");
  62         if (bpf_map_lookup_elem(map_fd[3], &key->wret, ip) != 0) {
  63                 printf("---;");
  64         } else {
  65                 for (i = 0; i < PERF_MAX_STACK_DEPTH; i++)
  66                         print_ksym(ip[i]);
  67         }
  68         printf(";%s %lld\n", key->waker, count);
  69 
  70         if ((key->tret == -EEXIST || key->wret == -EEXIST) && !warned) {
  71                 printf("stackmap collisions seen. Consider increasing size\n");
  72                 warned = true;
  73         } else if (((int)(key->tret) < 0 || (int)(key->wret) < 0)) {
  74                 printf("err stackid %d %d\n", key->tret, key->wret);
  75         }
  76 }
  77 
  78 static void print_stacks(int fd)
  79 {
  80         struct key_t key = {}, next_key;
  81         __u64 value;
  82 
  83         while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
  84                 bpf_map_lookup_elem(fd, &next_key, &value);
  85                 print_stack(&next_key, value);
  86                 key = next_key;
  87         }
  88 }
  89 
  90 static void int_exit(int sig)
  91 {
  92         print_stacks(map_fd[0]);
  93         exit(0);
  94 }
  95 
  96 int main(int argc, char **argv)
  97 {
  98         struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
  99         char filename[256];
 100         int delay = 1;
 101 
 102         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 103         setrlimit(RLIMIT_MEMLOCK, &r);
 104 
 105         signal(SIGINT, int_exit);
 106         signal(SIGTERM, int_exit);
 107 
 108         if (load_kallsyms()) {
 109                 printf("failed to process /proc/kallsyms\n");
 110                 return 2;
 111         }
 112 
 113         if (load_bpf_file(filename)) {
 114                 printf("%s", bpf_log_buf);
 115                 return 1;
 116         }
 117 
 118         if (argc > 1)
 119                 delay = atoi(argv[1]);
 120         sleep(delay);
 121         print_stacks(map_fd[0]);
 122 
 123         return 0;
 124 }