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 12 struct { 13 __uint(type, BPF_MAP_TYPE_CGROUP_ARRAY); 14 __uint(key_size, sizeof(u32)); 15 __uint(value_size, sizeof(u32)); 16 __uint(max_entries, 1); 17 } cgroup_map SEC(".maps"); 18 19 struct { 20 __uint(type, BPF_MAP_TYPE_ARRAY); 21 __type(key, u32); 22 __type(value, u64); 23 __uint(max_entries, 1); 24 } perf_map SEC(".maps"); 25 26 /* Writes the last PID that called sync to a map at index 0 */ 27 SEC("ksyscall/sync") 28 int bpf_prog1(struct pt_regs *ctx) 29 { 30 u64 pid = bpf_get_current_pid_tgid(); 31 int idx = 0; 32 33 if (!bpf_current_task_under_cgroup(&cgroup_map, 0)) 34 return 0; 35 36 bpf_map_update_elem(&perf_map, &idx, &pid, BPF_ANY); 37 return 0; 38 } 39 40 char _license[] SEC("license") = "GPL"; 41 u32 _version SEC("version") = LINUX_VERSION_CODE; 42