1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2020 Facebook 3 4 #include "vmlinux.h" 5 #include <bpf/bpf_helpers.h> 6 #include <bpf/bpf_core_read.h> 7 8 char _license[] SEC("license") = "GPL"; 9 10 /* shuffled layout for relocatable (CO-RE) reads */ 11 struct callback_head___shuffled { 12 void (*func)(struct callback_head___shuffled *head); 13 struct callback_head___shuffled *next; 14 }; 15 16 struct callback_head k_probe_in = {}; 17 struct callback_head___shuffled k_core_in = {}; 18 19 struct callback_head *u_probe_in = 0; 20 struct callback_head___shuffled *u_core_in = 0; 21 22 long k_probe_out = 0; 23 long u_probe_out = 0; 24 25 long k_core_out = 0; 26 long u_core_out = 0; 27 28 int my_pid = 0; 29 30 SEC("raw_tracepoint/sys_enter") 31 int handler(void *ctx) 32 { 33 int pid = bpf_get_current_pid_tgid() >> 32; 34 35 if (my_pid != pid) 36 return 0; 37 38 /* next pointers for kernel address space have to be initialized from 39 * BPF side, user-space mmaped addresses are stil user-space addresses 40 */ 41 k_probe_in.next = &k_probe_in; 42 __builtin_preserve_access_index(({k_core_in.next = &k_core_in;})); 43 44 k_probe_out = (long)BPF_PROBE_READ(&k_probe_in, next, next, func); 45 k_core_out = (long)BPF_CORE_READ(&k_core_in, next, next, func); 46 u_probe_out = (long)BPF_PROBE_READ_USER(u_probe_in, next, next, func); 47 u_core_out = (long)BPF_CORE_READ_USER(u_core_in, next, next, func); 48 49 return 0; 50 } 51