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