1 #include "vmlinux.h"
2 #include <bpf/bpf_helpers.h>
3 #include <bpf/bpf_core_read.h>
4 
5 const char LICENSE[] SEC("license") = "GPL";
6 
7 struct {
8 	__uint(type, BPF_MAP_TYPE_ARRAY);
9 	__uint(max_entries, 1);
10 	__type(key, __u32);
11 	__type(value, __u64);
12 } array SEC(".maps");
13 
14 __noinline int sub1(int x)
15 {
16 	int key = 0;
17 
18 	bpf_map_lookup_elem(&array, &key);
19 	return x + 1;
20 }
21 
22 static __noinline int sub5(int v);
23 
24 __noinline int sub2(int y)
25 {
26 	return sub5(y + 2);
27 }
28 
29 static __noinline int sub3(int z)
30 {
31 	return z + 3 + sub1(4);
32 }
33 
34 static __noinline int sub4(int w)
35 {
36 	int key = 0;
37 
38 	bpf_map_lookup_elem(&array, &key);
39 	return w + sub3(5) + sub1(6);
40 }
41 
42 /* sub5() is an identitify function, just to test weirder functions layout and
43  * call patterns
44  */
45 static __noinline int sub5(int v)
46 {
47 	return sub1(v) - 1; /* compensates sub1()'s + 1 */
48 }
49 
50 /* unfortunately verifier rejects `struct task_struct *t` as an unkown pointer
51  * type, so we need to accept pointer as integer and then cast it inside the
52  * function
53  */
54 __noinline int get_task_tgid(uintptr_t t)
55 {
56 	/* this ensures that CO-RE relocs work in multi-subprogs .text */
57 	return BPF_CORE_READ((struct task_struct *)(void *)t, tgid);
58 }
59 
60 int res1 = 0;
61 int res2 = 0;
62 int res3 = 0;
63 int res4 = 0;
64 
65 SEC("raw_tp/sys_enter")
66 int prog1(void *ctx)
67 {
68 	/* perform some CO-RE relocations to ensure they work with multi-prog
69 	 * sections correctly
70 	 */
71 	struct task_struct *t = (void *)bpf_get_current_task();
72 
73 	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
74 		return 1;
75 
76 	res1 = sub1(1) + sub3(2); /* (1 + 1) + (2 + 3 + (4 + 1)) = 12 */
77 	return 0;
78 }
79 
80 SEC("raw_tp/sys_exit")
81 int prog2(void *ctx)
82 {
83 	struct task_struct *t = (void *)bpf_get_current_task();
84 
85 	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
86 		return 1;
87 
88 	res2 = sub2(3) + sub3(4); /* (3 + 2) + (4 + 3 + (4 + 1)) = 17 */
89 	return 0;
90 }
91 
92 static int empty_callback(__u32 index, void *data)
93 {
94 	return 0;
95 }
96 
97 /* prog3 has the same section name as prog1 */
98 SEC("raw_tp/sys_enter")
99 int prog3(void *ctx)
100 {
101 	struct task_struct *t = (void *)bpf_get_current_task();
102 
103 	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
104 		return 1;
105 
106 	/* test that ld_imm64 with BPF_PSEUDO_FUNC doesn't get blinded */
107 	bpf_loop(1, empty_callback, NULL, 0);
108 
109 	res3 = sub3(5) + 6; /* (5 + 3 + (4 + 1)) + 6 = 19 */
110 	return 0;
111 }
112 
113 /* prog4 has the same section name as prog2 */
114 SEC("raw_tp/sys_exit")
115 int prog4(void *ctx)
116 {
117 	struct task_struct *t = (void *)bpf_get_current_task();
118 
119 	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))
120 		return 1;
121 
122 	res4 = sub4(7) + sub1(8); /* (7 + (5 + 3 + (4 + 1)) + (6 + 1)) + (8 + 1) = 36 */
123 	return 0;
124 }
125