| 1 | /* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me> |
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| 2 | * |
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| 3 | * This program is free software; you can redistribute it and/or |
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| 4 | * modify it under the terms of version 2 of the GNU General Public |
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| 5 | * License as published by the Free Software Foundation. |
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| 6 | */ |
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| 7 | |
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| 8 | #include "vmlinux.h" |
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| 9 | #include <linux/version.h> |
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| 10 | #include <bpf/bpf_helpers.h> |
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| 11 | #include <bpf/bpf_tracing.h> |
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| 12 | #include <bpf/bpf_core_read.h> |
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| 13 | |
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| 14 | struct { |
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| 15 | __uint(type, BPF_MAP_TYPE_CGROUP_ARRAY); |
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| 16 | __uint(key_size, sizeof(u32)); |
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| 17 | __uint(value_size, sizeof(u32)); |
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| 18 | __uint(max_entries, 1); |
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| 19 | } cgroup_map SEC(".maps" ); |
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| 20 | |
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| 21 | struct { |
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| 22 | __uint(type, BPF_MAP_TYPE_ARRAY); |
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| 23 | __type(key, u32); |
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| 24 | __type(value, u64); |
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| 25 | __uint(max_entries, 1); |
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| 26 | } perf_map SEC(".maps" ); |
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| 27 | |
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| 28 | /* Writes the last PID that called sync to a map at index 0 */ |
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| 29 | SEC("ksyscall/sync" ) |
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| 30 | int BPF_KSYSCALL(bpf_prog1) |
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| 31 | { |
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| 32 | u64 pid = bpf_get_current_pid_tgid(); |
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| 33 | int idx = 0; |
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| 34 | |
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| 35 | if (!bpf_current_task_under_cgroup(&cgroup_map, 0)) |
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| 36 | return 0; |
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| 37 | |
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| 38 | bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY); |
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| 39 | return 0; |
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| 40 | } |
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| 41 | |
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| 42 | char _license[] SEC("license" ) = "GPL" ; |
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| 43 | u32 _version SEC("version" ) = LINUX_VERSION_CODE; |
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| 44 | |
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