/* Copyright (c) 2016 Facebook
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  #include <linux/ptrace.h>
  #include <linux/version.h>
  #include <uapi/linux/bpf.h>
  #include <uapi/linux/bpf_perf_event.h>
  #include <uapi/linux/perf_event.h>
  #include "bpf_helpers.h"
  
  struct key_t {
  	char comm[TASK_COMM_LEN];
  	u32 kernstack;
  	u32 userstack;
  };
  
  struct bpf_map_def SEC("maps") counts = {
  	.type = BPF_MAP_TYPE_HASH,
  	.key_size = sizeof(struct key_t),
  	.value_size = sizeof(u64),
  	.max_entries = 10000,
  };
  
  struct bpf_map_def SEC("maps") stackmap = {
  	.type = BPF_MAP_TYPE_STACK_TRACE,
  	.key_size = sizeof(u32),
  	.value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
  	.max_entries = 10000,
  };
  
  #define KERN_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP)
  #define USER_STACKID_FLAGS (0 | BPF_F_FAST_STACK_CMP | BPF_F_USER_STACK)
  
  SEC("perf_event")
  int bpf_prog1(struct bpf_perf_event_data *ctx)
  {
  	char fmt[] = "CPU-%d period %lld ip %llx";
  	u32 cpu = bpf_get_smp_processor_id();
  	struct key_t key;
  	u64 *val, one = 1;
  
  	if (ctx->sample_period < 10000)
  		/* ignore warmup */
  		return 0;
  	bpf_get_current_comm(&key.comm, sizeof(key.comm));
  	key.kernstack = bpf_get_stackid(ctx, &stackmap, KERN_STACKID_FLAGS);
  	key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
  	if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
  		bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,

  				 PT_REGS_IP(&ctx->regs));

  		return 0;
  	}
  
  	val = bpf_map_lookup_elem(&counts, &key);
  	if (val)
  		(*val)++;
  	else
  		bpf_map_update_elem(&counts, &key, &one, BPF_NOEXIST);
  	return 0;
  }
  
  char _license[] SEC("license") = "GPL";