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0fb1170e DW |
1 | /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com |
2 | * Copyright (c) 2015 BMW Car IT GmbH | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of version 2 of the GNU General Public | |
6 | * License as published by the Free Software Foundation. | |
7 | */ | |
8 | #include <linux/version.h> | |
9 | #include <linux/ptrace.h> | |
10 | #include <uapi/linux/bpf.h> | |
7cf245a3 | 11 | #include <bpf/bpf_helpers.h> |
0fb1170e DW |
12 | |
13 | #define MAX_ENTRIES 20 | |
14 | #define MAX_CPU 4 | |
15 | ||
16 | /* We need to stick to static allocated memory (an array instead of | |
17 | * hash table) because managing dynamic memory from the | |
18 | * trace_preempt_[on|off] tracepoints hooks is not supported. | |
19 | */ | |
20 | ||
3677d0a1 DL |
21 | struct { |
22 | __uint(type, BPF_MAP_TYPE_ARRAY); | |
23 | __type(key, int); | |
24 | __type(value, u64); | |
25 | __uint(max_entries, MAX_CPU); | |
26 | } my_map SEC(".maps"); | |
0fb1170e DW |
27 | |
28 | SEC("kprobe/trace_preempt_off") | |
29 | int bpf_prog1(struct pt_regs *ctx) | |
30 | { | |
31 | int cpu = bpf_get_smp_processor_id(); | |
32 | u64 *ts = bpf_map_lookup_elem(&my_map, &cpu); | |
33 | ||
34 | if (ts) | |
35 | *ts = bpf_ktime_get_ns(); | |
36 | ||
37 | return 0; | |
38 | } | |
39 | ||
40 | static unsigned int log2(unsigned int v) | |
41 | { | |
42 | unsigned int r; | |
43 | unsigned int shift; | |
44 | ||
45 | r = (v > 0xFFFF) << 4; v >>= r; | |
46 | shift = (v > 0xFF) << 3; v >>= shift; r |= shift; | |
47 | shift = (v > 0xF) << 2; v >>= shift; r |= shift; | |
48 | shift = (v > 0x3) << 1; v >>= shift; r |= shift; | |
49 | r |= (v >> 1); | |
50 | ||
51 | return r; | |
52 | } | |
53 | ||
54 | static unsigned int log2l(unsigned long v) | |
55 | { | |
56 | unsigned int hi = v >> 32; | |
57 | ||
58 | if (hi) | |
59 | return log2(hi) + 32; | |
60 | else | |
61 | return log2(v); | |
62 | } | |
63 | ||
3677d0a1 DL |
64 | struct { |
65 | __uint(type, BPF_MAP_TYPE_ARRAY); | |
66 | __type(key, int); | |
67 | __type(value, long); | |
68 | __uint(max_entries, MAX_CPU * MAX_ENTRIES); | |
69 | } my_lat SEC(".maps"); | |
0fb1170e DW |
70 | |
71 | SEC("kprobe/trace_preempt_on") | |
72 | int bpf_prog2(struct pt_regs *ctx) | |
73 | { | |
74 | u64 *ts, cur_ts, delta; | |
75 | int key, cpu; | |
76 | long *val; | |
77 | ||
78 | cpu = bpf_get_smp_processor_id(); | |
79 | ts = bpf_map_lookup_elem(&my_map, &cpu); | |
80 | if (!ts) | |
81 | return 0; | |
82 | ||
83 | cur_ts = bpf_ktime_get_ns(); | |
84 | delta = log2l(cur_ts - *ts); | |
85 | ||
86 | if (delta > MAX_ENTRIES - 1) | |
87 | delta = MAX_ENTRIES - 1; | |
88 | ||
89 | key = cpu * MAX_ENTRIES + delta; | |
90 | val = bpf_map_lookup_elem(&my_lat, &key); | |
91 | if (val) | |
92 | __sync_fetch_and_add((long *)val, 1); | |
93 | ||
94 | return 0; | |
95 | ||
96 | } | |
97 | ||
98 | char _license[] SEC("license") = "GPL"; | |
99 | u32 _version SEC("version") = LINUX_VERSION_CODE; |