samples/bpf/trace_event_kern.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 <linux/ptrace.h>
   8 #include <linux/version.h>
   9 #include <uapi/linux/bpf.h>
  10 #include <uapi/linux/bpf_perf_event.h>
  11 #include <uapi/linux/perf_event.h>
  12 #include "bpf_helpers.h"
  13
  14 struct key_t {
  15         char comm[TASK_COMM_LEN];
  16         u32 kernstack;
  17         u32 userstack;
  18 };
  19
  20 struct bpf_map_def SEC("maps") counts = {
  21         .type = BPF_MAP_TYPE_HASH,
  22         .key_size = sizeof(struct key_t),
  23         .value_size = sizeof(u64),
  24         .max_entries = 10000,
  25 };
  26
  27 struct bpf_map_def SEC("maps") stackmap = {
  28         .type = BPF_MAP_TYPE_STACK_TRACE,
  29         .key_size = sizeof(u32),
  30         .value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
  31         .max_entries = 10000,
  32 };
  33
  34 #define KERN_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
  35 #define USER_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP | BPF_F_USER_STACK)
  36
  37 SEC("perf_event")
  38 int bpf_prog1(struct bpf_perf_event_data *ctx)
  39 {
  40         char time_fmt1[] = "Time Enabled: %llu, Time Running: %llu";
  41         char time_fmt2[] = "Get Time Failed, ErrCode: %d";
  42         char addr_fmt[] = "Address recorded on event: %llx";
  43         char fmt[] = "CPU-%d period %lld ip %llx";
  44         u32 cpu = bpf_get_smp_processor_id();
  45         struct bpf_perf_event_value value_buf;
  46         struct key_t key;
  47         u64 *val, one = 1;
  48         int ret;
  49
  50         if (ctx->sample_period < 10000)
  51                 /* ignore warmup */
  52                 return 0;
  53         bpf_get_current_comm(&key.comm, sizeof(key.comm));
  54         key.kernstack = bpf_get_stackid(ctx, &stackmap, KERN_STACKID_FLAGS);
  55         key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
  56         if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
  57                 bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
  58                                  PT_REGS_IP(&ctx->regs));
  59                 return 0;
  60         }
  61
  62         ret = bpf_perf_prog_read_value(ctx, (void *)&value_buf, sizeof(struct bpf_perf_event_value));
  63         if (!ret)
  64           bpf_trace_printk(time_fmt1, sizeof(time_fmt1), value_buf.enabled, value_buf.running);
  65         else
  66           bpf_trace_printk(time_fmt2, sizeof(time_fmt2), ret);
  67
  68         if (ctx->addr != 0)
  69           bpf_trace_printk(addr_fmt, sizeof(addr_fmt), ctx->addr);
  70
  71         val = bpf_map_lookup_elem(&counts, &key);
  72         if (val)
  73                 (*val)++;
  74         else
  75                 bpf_map_update_elem(&counts, &key, &one, BPF_NOEXIST);
  76         return 0;
  77 }
  78
  79 char _license[] SEC("license") = "GPL";