LXR linux/samples/bpf/trace_event

   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 <uapi/linux/bpf.h>
   9#include <uapi/linux/bpf_perf_event.h>
  10#include <uapi/linux/perf_event.h>
  11#include <bpf/bpf_helpers.h>
  12#include <bpf/bpf_tracing.h>
  13
  14struct key_t {
  15        char comm[TASK_COMM_LEN];
  16        u32 kernstack;
  17        u32 userstack;
  18};
  19
  20struct {
  21        __uint(type, BPF_MAP_TYPE_HASH);
  22        __type(key, struct key_t);
  23        __type(value, u64);
  24        __uint(max_entries, 10000);
  25} counts SEC(".maps");
  26
  27struct {
  28        __uint(type, BPF_MAP_TYPE_STACK_TRACE);
  29        __uint(key_size, sizeof(u32));
  30        __uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
  31        __uint(max_entries, 10000);
  32} stackmap SEC(".maps");
  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
  37SEC("perf_event")
  38int 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
  79char _license[] SEC("license") = "GPL";
  80