1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2020 Facebook */
3
4#include "vmlinux.h"
5#include <bpf/bpf_helpers.h>
6#include <bpf/bpf_core_read.h>
7#include <bpf/bpf_tracing.h>
8
9char _license[] SEC("license") = "GPL";
10
11struct bpf_testmod_test_read_ctx {
12	/* field order is mixed up */
13	size_t len;
14	char *buf;
15	loff_t off;
16} __attribute__((preserve_access_index));
17
18struct {
19	char in[256];
20	char out[256];
21	bool skip;
22	uint64_t my_pid_tgid;
23} data = {};
24
25struct core_reloc_module_output {
26	long long len;
27	long long off;
28	int read_ctx_sz;
29	bool read_ctx_exists;
30	bool buf_exists;
31	bool len_exists;
32	bool off_exists;
33	/* we have test_progs[-flavor], so cut flavor part */
34	char comm[sizeof("test_progs")];
35	int comm_len;
36};
37
38SEC("raw_tp/bpf_testmod_test_read")
39int BPF_PROG(test_core_module_probed,
40	     struct task_struct *task,
41	     struct bpf_testmod_test_read_ctx *read_ctx)
42{
43#if __has_builtin(__builtin_preserve_enum_value)
44	struct core_reloc_module_output *out = (void *)&data.out;
45	__u64 pid_tgid = bpf_get_current_pid_tgid();
46	__s32 real_tgid = (__s32)(pid_tgid >> 32);
47	__s32 real_pid = (__s32)pid_tgid;
48
49	if (data.my_pid_tgid != pid_tgid)
50		return 0;
51
52	if (BPF_CORE_READ(task, pid) != real_pid || BPF_CORE_READ(task, tgid) != real_tgid)
53		return 0;
54
55	out->len = BPF_CORE_READ(read_ctx, len);
56	out->off = BPF_CORE_READ(read_ctx, off);
57
58	out->read_ctx_sz = bpf_core_type_size(struct bpf_testmod_test_read_ctx);
59	out->read_ctx_exists = bpf_core_type_exists(struct bpf_testmod_test_read_ctx);
60	out->buf_exists = bpf_core_field_exists(read_ctx->buf);
61	out->off_exists = bpf_core_field_exists(read_ctx->off);
62	out->len_exists = bpf_core_field_exists(read_ctx->len);
63
64	out->comm_len = BPF_CORE_READ_STR_INTO(&out->comm, task, comm);
65#else
66	data.skip = true;
67#endif
68
69	return 0;
70}
71
72SEC("tp_btf/bpf_testmod_test_read")
73int BPF_PROG(test_core_module_direct,
74	     struct task_struct *task,
75	     struct bpf_testmod_test_read_ctx *read_ctx)
76{
77#if __has_builtin(__builtin_preserve_enum_value)
78	struct core_reloc_module_output *out = (void *)&data.out;
79	__u64 pid_tgid = bpf_get_current_pid_tgid();
80	__s32 real_tgid = (__s32)(pid_tgid >> 32);
81	__s32 real_pid = (__s32)pid_tgid;
82
83	if (data.my_pid_tgid != pid_tgid)
84		return 0;
85
86	if (task->pid != real_pid || task->tgid != real_tgid)
87		return 0;
88
89	out->len = read_ctx->len;
90	out->off = read_ctx->off;
91
92	out->read_ctx_sz = bpf_core_type_size(struct bpf_testmod_test_read_ctx);
93	out->read_ctx_exists = bpf_core_type_exists(struct bpf_testmod_test_read_ctx);
94	out->buf_exists = bpf_core_field_exists(read_ctx->buf);
95	out->off_exists = bpf_core_field_exists(read_ctx->off);
96	out->len_exists = bpf_core_field_exists(read_ctx->len);
97
98	out->comm_len = BPF_CORE_READ_STR_INTO(&out->comm, task, comm);
99#else
100	data.skip = true;
101#endif
102
103	return 0;
104}
105