1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
3
4 #include <vmlinux.h>
5 #include <bpf/bpf_helpers.h>
6 #include "bpf_misc.h"
7 #include "bpf_experimental.h"
8
9 struct node_data {
10 struct bpf_list_node l;
11 int key;
12 };
13
14 #define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
15 private(A) struct bpf_spin_lock glock;
16 private(A) struct bpf_list_head ghead __contains(node_data, l);
17
18 #define list_entry(ptr, type, member) container_of(ptr, type, member)
19 #define NR_NODES 16
20
21 int zero = 0;
22
23 SEC("syscall")
24 __retval(0)
list_peek(void * ctx)25 long list_peek(void *ctx)
26 {
27 struct bpf_list_node *l_n;
28 struct node_data *n;
29 int i, err = 0;
30
31 bpf_spin_lock(&glock);
32 l_n = bpf_list_front(&ghead);
33 bpf_spin_unlock(&glock);
34 if (l_n)
35 return __LINE__;
36
37 bpf_spin_lock(&glock);
38 l_n = bpf_list_back(&ghead);
39 bpf_spin_unlock(&glock);
40 if (l_n)
41 return __LINE__;
42
43 for (i = zero; i < NR_NODES && can_loop; i++) {
44 n = bpf_obj_new(typeof(*n));
45 if (!n)
46 return __LINE__;
47 n->key = i;
48 bpf_spin_lock(&glock);
49 bpf_list_push_back(&ghead, &n->l);
50 bpf_spin_unlock(&glock);
51 }
52
53 bpf_spin_lock(&glock);
54
55 l_n = bpf_list_front(&ghead);
56 if (!l_n) {
57 err = __LINE__;
58 goto done;
59 }
60
61 n = list_entry(l_n, struct node_data, l);
62 if (n->key != 0) {
63 err = __LINE__;
64 goto done;
65 }
66
67 l_n = bpf_list_back(&ghead);
68 if (!l_n) {
69 err = __LINE__;
70 goto done;
71 }
72
73 n = list_entry(l_n, struct node_data, l);
74 if (n->key != NR_NODES - 1) {
75 err = __LINE__;
76 goto done;
77 }
78
79 done:
80 bpf_spin_unlock(&glock);
81 return err;
82 }
83
84 #define TEST_FB(op, dolock) \
85 SEC("syscall") \
86 __failure __msg(MSG) \
87 long test_##op##_spinlock_##dolock(void *ctx) \
88 { \
89 struct bpf_list_node *l_n; \
90 __u64 jiffies = 0; \
91 \
92 if (dolock) \
93 bpf_spin_lock(&glock); \
94 l_n = bpf_list_##op(&ghead); \
95 if (l_n) \
96 jiffies = bpf_jiffies64(); \
97 if (dolock) \
98 bpf_spin_unlock(&glock); \
99 \
100 return !!jiffies; \
101 }
102
103 #define MSG "call bpf_list_{{(front|back).+}}; R0{{(_w)?}}=ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
104 TEST_FB(front, true)
105 TEST_FB(back, true)
106 #undef MSG
107
108 #define MSG "bpf_spin_lock at off=0 must be held for bpf_list_head"
109 TEST_FB(front, false)
110 TEST_FB(back, false)
111 #undef MSG
112
113 char _license[] SEC("license") = "GPL";
114