1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ 3 4 #include <linux/bpf.h> 5 #include <bpf/bpf_helpers.h> 6 #include <bpf/bpf_core_read.h> 7 8 struct task_struct___bad { 9 int pid; 10 int fake_field; 11 void *fake_field_subprog; 12 } __attribute__((preserve_access_index)); 13 14 SEC("?raw_tp/sys_enter") 15 int bad_relo(const void *ctx) 16 { 17 static struct task_struct___bad *t; 18 19 return bpf_core_field_size(t->fake_field); 20 } 21 22 static __noinline int bad_subprog(void) 23 { 24 static struct task_struct___bad *t; 25 26 /* ugliness below is a field offset relocation */ 27 return (void *)&t->fake_field_subprog - (void *)t; 28 } 29 30 SEC("?raw_tp/sys_enter") 31 int bad_relo_subprog(const void *ctx) 32 { 33 static struct task_struct___bad *t; 34 35 return bad_subprog() + bpf_core_field_size(t->pid); 36 } 37 38 struct { 39 __uint(type, BPF_MAP_TYPE_ARRAY); 40 __uint(max_entries, 1); 41 __type(key, int); 42 __type(value, int); 43 } existing_map SEC(".maps"); 44 45 struct { 46 __uint(type, BPF_MAP_TYPE_ARRAY); 47 __uint(max_entries, 1); 48 __type(key, int); 49 __type(value, int); 50 } missing_map SEC(".maps"); 51 52 SEC("?raw_tp/sys_enter") 53 int use_missing_map(const void *ctx) 54 { 55 int zero = 0, *value; 56 57 value = bpf_map_lookup_elem(&existing_map, &zero); 58 59 value = bpf_map_lookup_elem(&missing_map, &zero); 60 61 return value != NULL; 62 } 63 64 extern int bpf_nonexistent_kfunc(void) __ksym __weak; 65 66 SEC("?raw_tp/sys_enter") 67 int use_missing_kfunc(const void *ctx) 68 { 69 bpf_nonexistent_kfunc(); 70 71 return 0; 72 } 73 74 char _license[] SEC("license") = "GPL"; 75