1*4882a593Smuzhiyun /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
2*4882a593Smuzhiyun * Copyright (c) 2015 BMW Car IT GmbH
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * This program is free software; you can redistribute it and/or
5*4882a593Smuzhiyun * modify it under the terms of version 2 of the GNU General Public
6*4882a593Smuzhiyun * License as published by the Free Software Foundation.
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun #include <linux/version.h>
9*4882a593Smuzhiyun #include <linux/ptrace.h>
10*4882a593Smuzhiyun #include <uapi/linux/bpf.h>
11*4882a593Smuzhiyun #include <bpf/bpf_helpers.h>
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #define MAX_ENTRIES 20
14*4882a593Smuzhiyun #define MAX_CPU 4
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun /* We need to stick to static allocated memory (an array instead of
17*4882a593Smuzhiyun * hash table) because managing dynamic memory from the
18*4882a593Smuzhiyun * trace_preempt_[on|off] tracepoints hooks is not supported.
19*4882a593Smuzhiyun */
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun struct {
22*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_ARRAY);
23*4882a593Smuzhiyun __type(key, int);
24*4882a593Smuzhiyun __type(value, u64);
25*4882a593Smuzhiyun __uint(max_entries, MAX_CPU);
26*4882a593Smuzhiyun } my_map SEC(".maps");
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun SEC("kprobe/trace_preempt_off")
bpf_prog1(struct pt_regs * ctx)29*4882a593Smuzhiyun int bpf_prog1(struct pt_regs *ctx)
30*4882a593Smuzhiyun {
31*4882a593Smuzhiyun int cpu = bpf_get_smp_processor_id();
32*4882a593Smuzhiyun u64 *ts = bpf_map_lookup_elem(&my_map, &cpu);
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun if (ts)
35*4882a593Smuzhiyun *ts = bpf_ktime_get_ns();
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun return 0;
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun
log2(unsigned int v)40*4882a593Smuzhiyun static unsigned int log2(unsigned int v)
41*4882a593Smuzhiyun {
42*4882a593Smuzhiyun unsigned int r;
43*4882a593Smuzhiyun unsigned int shift;
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun r = (v > 0xFFFF) << 4; v >>= r;
46*4882a593Smuzhiyun shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
47*4882a593Smuzhiyun shift = (v > 0xF) << 2; v >>= shift; r |= shift;
48*4882a593Smuzhiyun shift = (v > 0x3) << 1; v >>= shift; r |= shift;
49*4882a593Smuzhiyun r |= (v >> 1);
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun return r;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun
log2l(unsigned long v)54*4882a593Smuzhiyun static unsigned int log2l(unsigned long v)
55*4882a593Smuzhiyun {
56*4882a593Smuzhiyun unsigned int hi = v >> 32;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun if (hi)
59*4882a593Smuzhiyun return log2(hi) + 32;
60*4882a593Smuzhiyun else
61*4882a593Smuzhiyun return log2(v);
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun struct {
65*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_ARRAY);
66*4882a593Smuzhiyun __type(key, int);
67*4882a593Smuzhiyun __type(value, long);
68*4882a593Smuzhiyun __uint(max_entries, MAX_CPU * MAX_ENTRIES);
69*4882a593Smuzhiyun } my_lat SEC(".maps");
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun SEC("kprobe/trace_preempt_on")
bpf_prog2(struct pt_regs * ctx)72*4882a593Smuzhiyun int bpf_prog2(struct pt_regs *ctx)
73*4882a593Smuzhiyun {
74*4882a593Smuzhiyun u64 *ts, cur_ts, delta;
75*4882a593Smuzhiyun int key, cpu;
76*4882a593Smuzhiyun long *val;
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun cpu = bpf_get_smp_processor_id();
79*4882a593Smuzhiyun ts = bpf_map_lookup_elem(&my_map, &cpu);
80*4882a593Smuzhiyun if (!ts)
81*4882a593Smuzhiyun return 0;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun cur_ts = bpf_ktime_get_ns();
84*4882a593Smuzhiyun delta = log2l(cur_ts - *ts);
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun if (delta > MAX_ENTRIES - 1)
87*4882a593Smuzhiyun delta = MAX_ENTRIES - 1;
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun key = cpu * MAX_ENTRIES + delta;
90*4882a593Smuzhiyun val = bpf_map_lookup_elem(&my_lat, &key);
91*4882a593Smuzhiyun if (val)
92*4882a593Smuzhiyun __sync_fetch_and_add((long *)val, 1);
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun return 0;
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun }
97*4882a593Smuzhiyun
98*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
99*4882a593Smuzhiyun u32 _version SEC("version") = LINUX_VERSION_CODE;
100