#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
#
# uflow Trace method execution flow in high-level languages.
# For Linux, uses BCC, eBPF.
#
# USAGE: uflow [-C CLASS] [-M METHOD] [-v] {java,perl,php,python,ruby,tcl} pid
#
# Copyright 2016 Sasha Goldshtein
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 27-Oct-2016 Sasha Goldshtein Created this.
from __future__ import print_function
import argparse
from bcc import BPF, USDT, utils
import ctypes as ct
import time
import os
languages = ["java", "perl", "php", "python", "ruby", "tcl"]
examples = """examples:
./uflow -l java 185 # trace Java method calls in process 185
./uflow -l ruby 134 # trace Ruby method calls in process 134
./uflow -M indexOf -l java 185 # trace only 'indexOf'-prefixed methods
./uflow -C '<stdin>' -l python 180 # trace only REPL-defined methods
"""
parser = argparse.ArgumentParser(
description="Trace method execution flow in high-level languages.",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-l", "--language", choices=languages,
help="language to trace")
parser.add_argument("pid", type=int, help="process id to attach to")
parser.add_argument("-M", "--method",
help="trace only calls to methods starting with this prefix")
parser.add_argument("-C", "--class", dest="clazz",
help="trace only calls to classes starting with this prefix")
parser.add_argument("-v", "--verbose", action="store_true",
help="verbose mode: print the BPF program (for debugging purposes)")
parser.add_argument("--ebpf", action="store_true",
help=argparse.SUPPRESS)
args = parser.parse_args()
usdt = USDT(pid=args.pid)
program = """
struct call_t {
u64 depth; // first bit is direction (0 entry, 1 return)
u64 pid; // (tgid << 32) + pid from bpf_get_current...
char clazz[80];
char method[80];
};
BPF_PERF_OUTPUT(calls);
BPF_HASH(entry, u64, u64);
"""
prefix_template = """
static inline bool prefix_%s(char *actual) {
char expected[] = "%s";
for (int i = 0; i < sizeof(expected) - 1; ++i) {
if (expected[i] != actual[i]) {
return false;
}
}
return true;
}
"""
if args.clazz:
program += prefix_template % ("class", args.clazz)
if args.method:
program += prefix_template % ("method", args.method)
trace_template = """
int NAME(struct pt_regs *ctx) {
u64 *depth, zero = 0, clazz = 0, method = 0 ;
struct call_t data = {};
READ_CLASS
READ_METHOD
bpf_probe_read(&data.clazz, sizeof(data.clazz), (void *)clazz);
bpf_probe_read(&data.method, sizeof(data.method), (void *)method);
FILTER_CLASS
FILTER_METHOD
data.pid = bpf_get_current_pid_tgid();
depth = entry.lookup_or_init(&data.pid, &zero);
data.depth = DEPTH;
UPDATE
calls.perf_submit(ctx, &data, sizeof(data));
return 0;
}
"""
def enable_probe(probe_name, func_name, read_class, read_method, is_return):
global program, trace_template, usdt
depth = "*depth + 1" if not is_return else "*depth | (1ULL << 63)"
update = "++(*depth);" if not is_return else "if (*depth) --(*depth);"
filter_class = "if (!prefix_class(data.clazz)) { return 0; }" \
if args.clazz else ""
filter_method = "if (!prefix_method(data.method)) { return 0; }" \
if args.method else ""
program += trace_template.replace("NAME", func_name) \
.replace("READ_CLASS", read_class) \
.replace("READ_METHOD", read_method) \
.replace("FILTER_CLASS", filter_class) \
.replace("FILTER_METHOD", filter_method) \
.replace("DEPTH", depth) \
.replace("UPDATE", update)
usdt.enable_probe_or_bail(probe_name, func_name)
usdt = USDT(pid=args.pid)
language = args.language
if not language:
language = utils.detect_language(languages, args.pid)
if language == "java":
enable_probe("method__entry", "java_entry",
"bpf_usdt_readarg(2, ctx, &clazz);",
"bpf_usdt_readarg(4, ctx, &method);", is_return=False)
enable_probe("method__return", "java_return",
"bpf_usdt_readarg(2, ctx, &clazz);",
"bpf_usdt_readarg(4, ctx, &method);", is_return=True)
elif language == "perl":
enable_probe("sub__entry", "perl_entry",
"bpf_usdt_readarg(2, ctx, &clazz);",
"bpf_usdt_readarg(1, ctx, &method);", is_return=False)
enable_probe("sub__return", "perl_return",
"bpf_usdt_readarg(2, ctx, &clazz);",
"bpf_usdt_readarg(1, ctx, &method);", is_return=True)
elif language == "php":
enable_probe("function__entry", "php_entry",
"bpf_usdt_readarg(4, ctx, &clazz);",
"bpf_usdt_readarg(1, ctx, &method);", is_return=False)
enable_probe("function__return", "php_return",
"bpf_usdt_readarg(4, ctx, &clazz);",
"bpf_usdt_readarg(1, ctx, &method);", is_return=True)
elif language == "python":
enable_probe("function__entry", "python_entry",
"bpf_usdt_readarg(1, ctx, &clazz);", # filename really
"bpf_usdt_readarg(2, ctx, &method);", is_return=False)
enable_probe("function__return", "python_return",
"bpf_usdt_readarg(1, ctx, &clazz);", # filename really
"bpf_usdt_readarg(2, ctx, &method);", is_return=True)
elif language == "ruby":
enable_probe("method__entry", "ruby_entry",
"bpf_usdt_readarg(1, ctx, &clazz);",
"bpf_usdt_readarg(2, ctx, &method);", is_return=False)
enable_probe("method__return", "ruby_return",
"bpf_usdt_readarg(1, ctx, &clazz);",
"bpf_usdt_readarg(2, ctx, &method);", is_return=True)
enable_probe("cmethod__entry", "ruby_centry",
"bpf_usdt_readarg(1, ctx, &clazz);",
"bpf_usdt_readarg(2, ctx, &method);", is_return=False)
enable_probe("cmethod__return", "ruby_creturn",
"bpf_usdt_readarg(1, ctx, &clazz);",
"bpf_usdt_readarg(2, ctx, &method);", is_return=True)
elif language == "tcl":
enable_probe("proc__args", "tcl_entry",
"", # no class/file info available
"bpf_usdt_readarg(1, ctx, &method);", is_return=False)
enable_probe("proc__return", "tcl_return",
"", # no class/file info available
"bpf_usdt_readarg(1, ctx, &method);", is_return=True)
else:
print("No language detected; use -l to trace a language.")
exit(1)
if args.ebpf or args.verbose:
if args.verbose:
print(usdt.get_text())
print(program)
if args.ebpf:
exit()
bpf = BPF(text=program, usdt_contexts=[usdt])
print("Tracing method calls in %s process %d... Ctrl-C to quit." %
(language, args.pid))
print("%-3s %-6s %-6s %-8s %s" % ("CPU", "PID", "TID", "TIME(us)", "METHOD"))
class CallEvent(ct.Structure):
_fields_ = [
("depth", ct.c_ulonglong),
("pid", ct.c_ulonglong),
("clazz", ct.c_char * 80),
("method", ct.c_char * 80)
]
start_ts = time.time()
def print_event(cpu, data, size):
event = ct.cast(data, ct.POINTER(CallEvent)).contents
depth = event.depth & (~(1 << 63))
direction = "<- " if event.depth & (1 << 63) else "-> "
print("%-3d %-6d %-6d %-8.3f %-40s" % (cpu, event.pid >> 32,
event.pid & 0xFFFFFFFF, time.time() - start_ts,
(" " * (depth - 1)) + direction + \
event.clazz.decode('utf-8', 'replace') + "." + \
event.method.decode('utf-8', 'replace')))
bpf["calls"].open_perf_buffer(print_event)
while 1:
bpf.perf_buffer_poll()