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1#!/usr/bin/env python
2# @lint-avoid-python-3-compatibility-imports
3#
4# killsnoop Trace signals issued by the kill() syscall.
5#           For Linux, uses BCC, eBPF. Embedded C.
6#
7# USAGE: killsnoop [-h] [-t] [-x] [-p PID]
8#
9# Copyright (c) 2015 Brendan Gregg.
10# Licensed under the Apache License, Version 2.0 (the "License")
11#
12# 20-Sep-2015   Brendan Gregg   Created this.
13
14from __future__ import print_function
15from bcc import BPF
16import argparse
17
18# arguments
19examples = """examples:
20    ./killsnoop           # trace all kill() signals
21    ./killsnoop -t        # include timestamps
22    ./killsnoop -x        # only show failed kills
23    ./killsnoop -p 181    # only trace PID 181
24"""
25parser = argparse.ArgumentParser(
26    description="Trace signals issued by the kill() syscall",
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 opens")
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_pid, u32, int);
43BPF_HASH(args_sig, u32, int);
44
45int kprobe__sys_kill(struct pt_regs *ctx, int tpid, int sig)
46{
47    u32 pid = bpf_get_current_pid_tgid();
48
49    FILTER
50    args_pid.update(&pid, &tpid);
51    args_sig.update(&pid, &sig);
52
53    return 0;
54};
55
56int kretprobe__sys_kill(struct pt_regs *ctx)
57{
58    int *tpidp, *sigp, ret = ctx->ax;
59    u32 pid = bpf_get_current_pid_tgid();
60
61    tpidp = args_pid.lookup(&pid);
62    sigp = args_sig.lookup(&pid);
63    if (tpidp == 0 || sigp == 0) {
64        return 0;   // missed entry
65    }
66
67    bpf_trace_printk("%d %d %d\\n", *tpidp, *sigp, ret);
68    args_pid.delete(&pid);
69    args_sig.delete(&pid);
70
71    return 0;
72}
73"""
74if args.pid:
75    bpf_text = bpf_text.replace('FILTER',
76        'if (pid != %s) { return 0; }' % args.pid)
77else:
78    bpf_text = bpf_text.replace('FILTER', '')
79if debug:
80    print(bpf_text)
81
82# initialize BPF
83b = BPF(text=bpf_text)
84
85# header
86if args.timestamp:
87    print("%-14s" % ("TIME(s)"), end="")
88print("%-6s %-16s %-4s %-6s %s" % ("PID", "COMM", "SIG", "TPID", "RESULT"))
89
90start_ts = 0
91
92# format output
93while 1:
94    (task, pid, cpu, flags, ts, msg) = b.trace_fields()
95    (tpid_s, sig_s, ret_s) = msg.split(" ")
96
97    ret = int(ret_s)
98    if (args.failed and (ret >= 0)):
99        continue
100
101    # print columns
102    if args.timestamp:
103        if start_ts == 0:
104            start_ts = ts
105        print("%-14.9f" % (ts - start_ts), end="")
106    print("%-6d %-16s %-4s %-6s %s" % (pid, task, sig_s, tpid_s, ret_s))
107