• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1#!/usr/bin/python
2# @lint-avoid-python-3-compatibility-imports
3#
4# statsnoop Trace stat() syscalls.
5#           For Linux, uses BCC, eBPF. Embedded C.
6#
7# USAGE: statsnoop [-h] [-t] [-x] [-p PID]
8#
9# Copyright 2016 Netflix, Inc.
10# Licensed under the Apache License, Version 2.0 (the "License")
11#
12# 08-Feb-2016   Brendan Gregg   Created this.
13
14from __future__ import print_function
15from bcc import BPF
16import argparse
17
18# arguments
19examples = """examples:
20    ./statsnoop           # trace all stat() syscalls
21    ./statsnoop -t        # include timestamps
22    ./statsnoop -x        # only show failed stats
23    ./statsnoop -p 181    # only trace PID 181
24"""
25parser = argparse.ArgumentParser(
26    description="Trace stat() syscalls",
27    formatter_class=argparse.RawDescriptionHelpFormatter,
28    epilog=examples)
29parser.add_argument("-t", "--timestamp", action="store_true",
30    help="include timestamp on output")
31parser.add_argument("-x", "--failed", action="store_true",
32    help="only show failed stats")
33parser.add_argument("-p", "--pid",
34    help="trace this PID only")
35args = parser.parse_args()
36debug = 0
37
38# define BPF program
39bpf_text = """
40#include <uapi/linux/ptrace.h>
41
42BPF_HASH(args_filename, u32, const char *);
43
44int trace_entry(struct pt_regs *ctx, const char __user *filename)
45{
46    u32 pid = bpf_get_current_pid_tgid();
47
48    FILTER
49    args_filename.update(&pid, &filename);
50
51    return 0;
52};
53
54int trace_return(struct pt_regs *ctx)
55{
56    const char **filenamep;
57    int ret = ctx->ax;
58    u32 pid = bpf_get_current_pid_tgid();
59
60    filenamep = args_filename.lookup(&pid);
61    if (filenamep == 0) {
62        // missed entry
63        return 0;
64    }
65
66    bpf_trace_printk("%d %s\\n", ret, *filenamep);
67    args_filename.delete(&pid);
68
69    return 0;
70}
71"""
72if args.pid:
73    bpf_text = bpf_text.replace('FILTER',
74        'if (pid != %s) { return 0; }' % args.pid)
75else:
76    bpf_text = bpf_text.replace('FILTER', '')
77if debug:
78    print(bpf_text)
79
80# initialize BPF
81b = BPF(text=bpf_text)
82b.attach_kprobe(event="sys_stat", fn_name="trace_entry")
83b.attach_kprobe(event="sys_statfs", fn_name="trace_entry")
84b.attach_kprobe(event="sys_newstat", fn_name="trace_entry")
85b.attach_kretprobe(event="sys_stat", fn_name="trace_return")
86b.attach_kretprobe(event="sys_statfs", fn_name="trace_return")
87b.attach_kretprobe(event="sys_newstat", fn_name="trace_return")
88
89# header
90if args.timestamp:
91    print("%-14s" % ("TIME(s)"), end="")
92print("%-6s %-16s %4s %3s %s" % ("PID", "COMM", "FD", "ERR", "PATH"))
93
94start_ts = 0
95
96# format output
97while 1:
98    (task, pid, cpu, flags, ts, msg) = b.trace_fields()
99    (ret_s, filename) = msg.split(" ", 1)
100
101    ret = int(ret_s)
102    if (args.failed and (ret >= 0)):
103        continue
104
105    # split return value into FD and errno columns
106    if ret >= 0:
107        fd_s = ret
108        err = 0
109    else:
110        fd_s = "-1"
111        err = - ret
112
113    # print columns
114    if args.timestamp:
115        if start_ts == 0:
116            start_ts = ts
117        print("%-14.9f" % (ts - start_ts), end="")
118    print("%-6d %-16s %4s %3s %s" % (pid, task, fd_s, err, filename))
119