1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2019 Facebook
3
4#include <linux/bpf.h>
5#include <stdint.h>
6#include <stdbool.h>
7#include <bpf/bpf_helpers.h>
8#include <bpf/bpf_core_read.h>
9
10char _license[] SEC("license") = "GPL";
11
12struct {
13 char in[256];
14 char out[256];
15 bool skip;
16 uint64_t my_pid_tgid;
17} data = {};
18
19struct core_reloc_kernel_output {
20 int valid[10];
21 /* we have test_progs[-flavor], so cut flavor part */
22 char comm[sizeof("test_progs")];
23 int comm_len;
24 bool local_task_struct_matches;
25};
26
27struct task_struct {
28 int pid;
29 int tgid;
30 char comm[16];
31 struct task_struct *group_leader;
32};
33
34struct mm_struct___wrong {
35 int abc_whatever_should_not_exist;
36};
37
38struct task_struct___local {
39 int pid;
40 struct mm_struct___wrong *mm;
41};
42
43#define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)
44
45SEC("raw_tracepoint/sys_enter")
46int test_core_kernel(void *ctx)
47{
48 /* Support for the BPF_TYPE_MATCHES argument to the
49 * __builtin_preserve_type_info builtin was added at some point during
50 * development of clang 15 and it's what we require for this test.
51 */
52#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
53 struct task_struct *task = (void *)bpf_get_current_task();
54 struct core_reloc_kernel_output *out = (void *)&data.out;
55 uint64_t pid_tgid = bpf_get_current_pid_tgid();
56 int32_t real_tgid = (int32_t)pid_tgid;
57 int pid, tgid;
58
59 if (data.my_pid_tgid != pid_tgid)
60 return 0;
61
62 if (CORE_READ(&pid, &task->pid) ||
63 CORE_READ(&tgid, &task->tgid))
64 return 1;
65
66 /* validate pid + tgid matches */
67 out->valid[0] = (((uint64_t)pid << 32) | tgid) == pid_tgid;
68
69 /* test variadic BPF_CORE_READ macros */
70 out->valid[1] = BPF_CORE_READ(task,
71 tgid) == real_tgid;
72 out->valid[2] = BPF_CORE_READ(task,
73 group_leader,
74 tgid) == real_tgid;
75 out->valid[3] = BPF_CORE_READ(task,
76 group_leader, group_leader,
77 tgid) == real_tgid;
78 out->valid[4] = BPF_CORE_READ(task,
79 group_leader, group_leader, group_leader,
80 tgid) == real_tgid;
81 out->valid[5] = BPF_CORE_READ(task,
82 group_leader, group_leader, group_leader,
83 group_leader,
84 tgid) == real_tgid;
85 out->valid[6] = BPF_CORE_READ(task,
86 group_leader, group_leader, group_leader,
87 group_leader, group_leader,
88 tgid) == real_tgid;
89 out->valid[7] = BPF_CORE_READ(task,
90 group_leader, group_leader, group_leader,
91 group_leader, group_leader, group_leader,
92 tgid) == real_tgid;
93 out->valid[8] = BPF_CORE_READ(task,
94 group_leader, group_leader, group_leader,
95 group_leader, group_leader, group_leader,
96 group_leader,
97 tgid) == real_tgid;
98 out->valid[9] = BPF_CORE_READ(task,
99 group_leader, group_leader, group_leader,
100 group_leader, group_leader, group_leader,
101 group_leader, group_leader,
102 tgid) == real_tgid;
103
104 /* test BPF_CORE_READ_STR_INTO() returns correct code and contents */
105 out->comm_len = BPF_CORE_READ_STR_INTO(
106 &out->comm, task,
107 group_leader, group_leader, group_leader, group_leader,
108 group_leader, group_leader, group_leader, group_leader,
109 comm);
110
111 out->local_task_struct_matches = bpf_core_type_matches(struct task_struct___local);
112#else
113 data.skip = true;
114#endif
115 return 0;
116}
117
118

source code of linux/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c