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323 lines
8.3 KiB
323 lines
8.3 KiB
#!/usr/bin/env python
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# @lint-avoid-python-3-compatibility-imports
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#
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# shmsnoop Trace shm*() syscalls.
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# For Linux, uses BCC, eBPF. Embedded C.
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#
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# USAGE: shmsnoop [-h] [-T] [-x] [-p PID] [-d DURATION] [-t TID] [-n NAME]
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#
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# Copyright (c) 2018 Jiri Olsa.
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# Licensed under the Apache License, Version 2.0 (the "License")
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#
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# 08-Oct-2018 Jiri Olsa Created this.
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from __future__ import print_function
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from bcc import ArgString, BPF
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import argparse
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import ctypes as ct
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from datetime import datetime, timedelta
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# arguments
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examples = """examples:
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./shmsnoop # trace all shm*() syscalls
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./shmsnoop -T # include timestamps
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./shmsnoop -p 181 # only trace PID 181
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./shmsnoop -t 123 # only trace TID 123
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./shmsnoop -d 10 # trace for 10 seconds only
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./shmsnoop -n main # only print process names containing "main"
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"""
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parser = argparse.ArgumentParser(
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description="Trace shm*() syscalls",
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formatter_class=argparse.RawDescriptionHelpFormatter,
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epilog=examples)
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parser.add_argument("-T", "--timestamp", action="store_true",
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help="include timestamp on output")
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parser.add_argument("-p", "--pid",
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help="trace this PID only")
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parser.add_argument("-t", "--tid",
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help="trace this TID only")
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parser.add_argument("-d", "--duration",
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help="total duration of trace in seconds")
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parser.add_argument("-n", "--name",
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type=ArgString,
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help="only print process names containing this name")
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parser.add_argument("--ebpf", action="store_true",
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help=argparse.SUPPRESS)
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args = parser.parse_args()
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debug = 0
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if args.duration:
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args.duration = timedelta(seconds=int(args.duration))
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# define BPF program
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bpf_text = """
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#include <uapi/linux/ptrace.h>
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#include <uapi/linux/limits.h>
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#include <linux/sched.h>
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struct val_t {
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u64 id;
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u64 ts;
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int sys;
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unsigned long key;
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unsigned long size;
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unsigned long shmflg;
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unsigned long shmid;
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unsigned long cmd;
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unsigned long buf;
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unsigned long shmaddr;
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unsigned long ret;
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char comm[TASK_COMM_LEN];
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};
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BPF_HASH(infotmp, u64, struct val_t);
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BPF_PERF_OUTPUT(events);
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enum {
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SYS_SHMGET,
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SYS_SHMAT,
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SYS_SHMDT,
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SYS_SHMCTL,
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};
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static int enter(struct val_t *val)
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{
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u64 id = bpf_get_current_pid_tgid();
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u32 pid = id >> 32; // PID is higher part
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u32 tid = id; // Cast and get the lower part
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FILTER
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val->id = id;
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infotmp.update(&id, val);
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return 0;
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}
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int trace_return(struct pt_regs *ctx)
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{
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u64 id = bpf_get_current_pid_tgid();
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u64 tsp = bpf_ktime_get_ns();
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struct val_t *val;
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val = infotmp.lookup(&id);
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if (val == 0)
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return 0;
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if (bpf_get_current_comm(&val->comm, sizeof(val->comm)) != 0)
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goto out;
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val->ts = tsp / 1000;
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val->ret = PT_REGS_RC(ctx);
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events.perf_submit(ctx, val, sizeof(*val));
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out:
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infotmp.delete(&id);
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return 0;
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}
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int syscall__shmget(struct pt_regs *ctx, u64 key, u64 size, u64 shmflg)
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{
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struct val_t val = {
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.sys = SYS_SHMGET,
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};
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val.key = key;
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val.size = size;
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val.shmflg = shmflg;
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return enter(&val);
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};
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int syscall__shmat(struct pt_regs *ctx, u64 shmid, u64 shmaddr, u64 shmflg)
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{
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struct val_t val = {
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.sys = SYS_SHMAT,
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};
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val.shmid = shmid;
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val.shmaddr = shmaddr;
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val.shmflg = shmflg;
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return enter(&val);
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};
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int syscall__shmdt(struct pt_regs *ctx, u64 shmaddr)
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{
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struct val_t val = {
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.sys = SYS_SHMDT,
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};
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val.shmaddr = shmaddr;
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return enter(&val);
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};
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int syscall__shmctl(struct pt_regs *ctx, u64 shmid, u64 cmd, u64 buf)
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{
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struct val_t val = {
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.sys = SYS_SHMCTL,
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};
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val.shmid = shmid;
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val.cmd = cmd;
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val.buf = buf;
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return enter(&val);
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};
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"""
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if args.tid: # TID trumps PID
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bpf_text = bpf_text.replace('FILTER',
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'if (tid != %s) { return 0; }' % args.tid)
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elif args.pid:
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bpf_text = bpf_text.replace('FILTER',
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'if (pid != %s) { return 0; }' % args.pid)
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else:
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bpf_text = bpf_text.replace('FILTER', '')
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if debug or args.ebpf:
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print(bpf_text)
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if args.ebpf:
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exit()
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# initialize BPF
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b = BPF(text=bpf_text)
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syscall_fnname = b.get_syscall_fnname("shmget")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__shmget")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_return")
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syscall_fnname = b.get_syscall_fnname("shmat")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__shmat")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_return")
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syscall_fnname = b.get_syscall_fnname("shmdt")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__shmdt")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_return")
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syscall_fnname = b.get_syscall_fnname("shmctl")
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if BPF.ksymname(syscall_fnname) != -1:
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b.attach_kprobe(event=syscall_fnname, fn_name="syscall__shmctl")
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b.attach_kretprobe(event=syscall_fnname, fn_name="trace_return")
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TASK_COMM_LEN = 16 # linux/sched.h
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SYS_SHMGET = 0
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SYS_SHMAT = 1
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SYS_SHMDT = 2
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SYS_SHMCTL = 3
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initial_ts = 0
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class Data(ct.Structure):
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_fields_ = [
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("id", ct.c_ulonglong),
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("ts", ct.c_ulonglong),
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("sys", ct.c_int),
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("key", ct.c_ulong),
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("size", ct.c_ulong),
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("shmflg", ct.c_ulong),
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("shmid", ct.c_ulong),
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("cmd", ct.c_ulong),
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("buf", ct.c_ulong),
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("shmaddr", ct.c_ulong),
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("ret", ct.c_ulong),
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("comm", ct.c_char * TASK_COMM_LEN),
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]
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# header
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if args.timestamp:
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print("%-14s" % ("TIME(s)"), end="")
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print("%-6s %-16s %6s %16s ARGs" %
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("TID" if args.tid else "PID", "COMM", "SYS", "RET"))
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def sys_name(sys):
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switcher = {
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SYS_SHMGET: "SHMGET",
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SYS_SHMAT: "SHMAT",
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SYS_SHMDT: "SHMDT",
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SYS_SHMCTL: "SHMCTL",
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}
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return switcher.get(sys, "N/A")
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shmget_flags = [
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{ 'name' : 'IPC_CREAT', 'value' : 0o1000 },
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{ 'name' : 'IPC_EXCL', 'value' : 0o2000 },
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{ 'name' : 'SHM_HUGETLB', 'value' : 0o4000 },
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{ 'name' : 'SHM_HUGE_2MB', 'value' : 21 << 26 },
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{ 'name' : 'SHM_HUGE_1GB', 'value' : 30 << 26 },
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{ 'name' : 'SHM_NORESERVE', 'value' : 0o10000 },
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{ 'name' : 'SHM_EXEC', 'value' : 0o100000 }
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]
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shmat_flags = [
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{ 'name' : 'SHM_RDONLY', 'value' : 0o10000 },
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{ 'name' : 'SHM_RND', 'value' : 0o20000 },
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{ 'name' : 'SHM_REMAP', 'value' : 0o40000 },
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{ 'name' : 'SHM_EXEC', 'value' : 0o100000 },
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]
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def shmflg_str(val, flags):
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cur = filter(lambda x : x['value'] & val, flags)
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str = "0x%x" % val
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if (not val):
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return str
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str += " ("
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cnt = 0
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for x in cur:
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if cnt:
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str += "|"
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str += x['name']
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val &= ~x['value']
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cnt += 1
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if val != 0 or not cnt:
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if cnt:
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str += "|"
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str += "0%o" % val
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str += ")"
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return str
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# process event
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def print_event(cpu, data, size):
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event = ct.cast(data, ct.POINTER(Data)).contents
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global initial_ts
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if not initial_ts:
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initial_ts = event.ts
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if args.name and bytes(args.name) not in event.comm:
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return
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if args.timestamp:
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delta = event.ts - initial_ts
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print("%-14.9f" % (float(delta) / 1000000), end="")
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print("%-6d %-16s %6s %16lx " %
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(event.id & 0xffffffff if args.tid else event.id >> 32,
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event.comm.decode(), sys_name(event.sys), event.ret), end = '')
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if event.sys == SYS_SHMGET:
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print("key: 0x%lx, size: %lu, shmflg: %s" %
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(event.key, event.size, shmflg_str(event.shmflg, shmget_flags)))
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if event.sys == SYS_SHMAT:
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print("shmid: 0x%lx, shmaddr: 0x%lx, shmflg: %s" %
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(event.shmid, event.shmaddr, shmflg_str(event.shmflg, shmat_flags)))
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if event.sys == SYS_SHMDT:
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print("shmaddr: 0x%lx" % (event.shmaddr))
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if event.sys == SYS_SHMCTL:
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print("shmid: 0x%lx, cmd: %lu, buf: 0x%x" % (event.shmid, event.cmd, event.buf))
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# loop with callback to print_event
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b["events"].open_perf_buffer(print_event, page_cnt=64)
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start_time = datetime.now()
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while not args.duration or datetime.now() - start_time < args.duration:
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try:
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b.perf_buffer_poll(timeout=1000)
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except KeyboardInterrupt:
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exit()
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