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99 lines
2.1 KiB
99 lines
2.1 KiB
/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com |
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* Copyright (c) 2015 BMW Car IT GmbH |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of version 2 of the GNU General Public |
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* License as published by the Free Software Foundation. |
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*/ |
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#include <linux/version.h> |
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#include <linux/ptrace.h> |
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#include <uapi/linux/bpf.h> |
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#include <bpf/bpf_helpers.h> |
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#define MAX_ENTRIES 20 |
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#define MAX_CPU 4 |
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/* We need to stick to static allocated memory (an array instead of |
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* hash table) because managing dynamic memory from the |
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* trace_preempt_[on|off] tracepoints hooks is not supported. |
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*/ |
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struct { |
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__uint(type, BPF_MAP_TYPE_ARRAY); |
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__type(key, int); |
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__type(value, u64); |
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__uint(max_entries, MAX_CPU); |
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} my_map SEC(".maps"); |
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SEC("kprobe/trace_preempt_off") |
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int bpf_prog1(struct pt_regs *ctx) |
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{ |
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int cpu = bpf_get_smp_processor_id(); |
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u64 *ts = bpf_map_lookup_elem(&my_map, &cpu); |
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if (ts) |
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*ts = bpf_ktime_get_ns(); |
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return 0; |
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} |
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static unsigned int log2(unsigned int v) |
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{ |
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unsigned int r; |
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unsigned int shift; |
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r = (v > 0xFFFF) << 4; v >>= r; |
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shift = (v > 0xFF) << 3; v >>= shift; r |= shift; |
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shift = (v > 0xF) << 2; v >>= shift; r |= shift; |
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shift = (v > 0x3) << 1; v >>= shift; r |= shift; |
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r |= (v >> 1); |
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return r; |
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} |
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static unsigned int log2l(unsigned long v) |
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{ |
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unsigned int hi = v >> 32; |
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if (hi) |
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return log2(hi) + 32; |
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else |
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return log2(v); |
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} |
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struct { |
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__uint(type, BPF_MAP_TYPE_ARRAY); |
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__type(key, int); |
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__type(value, long); |
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__uint(max_entries, MAX_CPU * MAX_ENTRIES); |
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} my_lat SEC(".maps"); |
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SEC("kprobe/trace_preempt_on") |
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int bpf_prog2(struct pt_regs *ctx) |
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{ |
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u64 *ts, cur_ts, delta; |
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int key, cpu; |
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long *val; |
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cpu = bpf_get_smp_processor_id(); |
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ts = bpf_map_lookup_elem(&my_map, &cpu); |
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if (!ts) |
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return 0; |
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cur_ts = bpf_ktime_get_ns(); |
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delta = log2l(cur_ts - *ts); |
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if (delta > MAX_ENTRIES - 1) |
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delta = MAX_ENTRIES - 1; |
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key = cpu * MAX_ENTRIES + delta; |
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val = bpf_map_lookup_elem(&my_lat, &key); |
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if (val) |
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__sync_fetch_and_add((long *)val, 1); |
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return 0; |
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} |
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char _license[] SEC("license") = "GPL"; |
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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