1*387f9dfdSAndroid Build Coastguard Worker#!/usr/bin/python 2*387f9dfdSAndroid Build Coastguard Worker# 3*387f9dfdSAndroid Build Coastguard Worker# urandomread Example of instrumenting a kernel tracepoint. 4*387f9dfdSAndroid Build Coastguard Worker# For Linux, uses BCC, BPF. Embedded C. 5*387f9dfdSAndroid Build Coastguard Worker# 6*387f9dfdSAndroid Build Coastguard Worker# REQUIRES: Linux 4.7+ (BPF_PROG_TYPE_TRACEPOINT support). 7*387f9dfdSAndroid Build Coastguard Worker# 8*387f9dfdSAndroid Build Coastguard Worker# Test by running this, then in another shell, run: 9*387f9dfdSAndroid Build Coastguard Worker# dd if=/dev/urandom of=/dev/null bs=1k count=5 10*387f9dfdSAndroid Build Coastguard Worker# 11*387f9dfdSAndroid Build Coastguard Worker# Copyright 2016 Netflix, Inc. 12*387f9dfdSAndroid Build Coastguard Worker# Licensed under the Apache License, Version 2.0 (the "License") 13*387f9dfdSAndroid Build Coastguard Worker 14*387f9dfdSAndroid Build Coastguard Workerfrom __future__ import print_function 15*387f9dfdSAndroid Build Coastguard Workerfrom bcc import BPF 16*387f9dfdSAndroid Build Coastguard Workerfrom bcc.utils import printb 17*387f9dfdSAndroid Build Coastguard Worker 18*387f9dfdSAndroid Build Coastguard Worker# load BPF program 19*387f9dfdSAndroid Build Coastguard Workerb = BPF(text=""" 20*387f9dfdSAndroid Build Coastguard WorkerTRACEPOINT_PROBE(random, urandom_read) { 21*387f9dfdSAndroid Build Coastguard Worker // args is from /sys/kernel/debug/tracing/events/random/urandom_read/format 22*387f9dfdSAndroid Build Coastguard Worker bpf_trace_printk("%d\\n", args->got_bits); 23*387f9dfdSAndroid Build Coastguard Worker return 0; 24*387f9dfdSAndroid Build Coastguard Worker} 25*387f9dfdSAndroid Build Coastguard Worker""") 26*387f9dfdSAndroid Build Coastguard Worker 27*387f9dfdSAndroid Build Coastguard Worker# header 28*387f9dfdSAndroid Build Coastguard Workerprint("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "GOTBITS")) 29*387f9dfdSAndroid Build Coastguard Worker 30*387f9dfdSAndroid Build Coastguard Worker# format output 31*387f9dfdSAndroid Build Coastguard Workerwhile 1: 32*387f9dfdSAndroid Build Coastguard Worker try: 33*387f9dfdSAndroid Build Coastguard Worker (task, pid, cpu, flags, ts, msg) = b.trace_fields() 34*387f9dfdSAndroid Build Coastguard Worker except ValueError: 35*387f9dfdSAndroid Build Coastguard Worker continue 36*387f9dfdSAndroid Build Coastguard Worker except KeyboardInterrupt: 37*387f9dfdSAndroid Build Coastguard Worker exit() 38*387f9dfdSAndroid Build Coastguard Worker printb(b"%-18.9f %-16s %-6d %s" % (ts, task, pid, msg)) 39