1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Test weak ksyms.
4  *
5  * Copyright (c) 2021 Google
6  */
7 
8 #include "vmlinux.h"
9 
10 #include <bpf/bpf_helpers.h>
11 
12 int out__existing_typed = -1;
13 __u64 out__existing_typeless = -1;
14 
15 __u64 out__non_existent_typeless = -1;
16 __u64 out__non_existent_typed = -1;
17 
18 /* existing weak symbols */
19 
20 /* test existing weak symbols can be resolved. */
21 extern const struct rq runqueues __ksym __weak; /* typed */
22 extern const void bpf_prog_active __ksym __weak; /* typeless */
23 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak;
24 void bpf_testmod_test_mod_kfunc(int i) __ksym __weak;
25 
26 
27 /* non-existent weak symbols. */
28 
29 /* typeless symbols, default to zero. */
30 extern const void bpf_link_fops1 __ksym __weak;
31 
32 /* typed symbols, default to zero. */
33 extern const int bpf_link_fops2 __ksym __weak;
34 void invalid_kfunc(void) __ksym __weak;
35 
36 SEC("raw_tp/sys_enter")
37 int pass_handler(const void *ctx)
38 {
39 	struct rq *rq;
40 
41 	/* tests existing symbols. */
42 	rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 0);
43 	if (rq && bpf_ksym_exists(&runqueues))
44 		out__existing_typed = rq->cpu;
45 	out__existing_typeless = (__u64)&bpf_prog_active;
46 
47 	/* tests non-existent symbols. */
48 	out__non_existent_typeless = (__u64)&bpf_link_fops1;
49 
50 	/* tests non-existent symbols. */
51 	out__non_existent_typed = (__u64)&bpf_link_fops2;
52 
53 	if (&bpf_link_fops2) /* can't happen */
54 		out__non_existent_typed = (__u64)bpf_per_cpu_ptr(&bpf_link_fops2, 0);
55 
56 	if (!bpf_ksym_exists(bpf_task_acquire))
57 		/* dead code won't be seen by the verifier */
58 		bpf_task_acquire(0);
59 
60 	if (!bpf_ksym_exists(bpf_testmod_test_mod_kfunc))
61 		/* dead code won't be seen by the verifier */
62 		bpf_testmod_test_mod_kfunc(0);
63 
64 	if (bpf_ksym_exists(invalid_kfunc))
65 		/* dead code won't be seen by the verifier */
66 		invalid_kfunc();
67 
68 	return 0;
69 }
70 
71 char _license[] SEC("license") = "GPL";
72