1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2021 Facebook */
3#include <linux/stddef.h>
4#include <linux/bpf.h>
5#include <bpf/bpf_helpers.h>
6#include <bpf/bpf_tracing.h>
7#include <../../../tools/include/linux/filter.h>
8#include <linux/btf.h>
9
10char _license[] SEC("license") = "GPL";
11
12struct args {
13	__u64 log_buf;
14	__u32 log_size;
15	int max_entries;
16	int map_fd;
17	int prog_fd;
18	int btf_fd;
19};
20
21#define BTF_INFO_ENC(kind, kind_flag, vlen) \
22	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
23#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
24#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
25	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
26#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
27	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
28	BTF_INT_ENC(encoding, bits_offset, bits)
29
30static int btf_load(void)
31{
32	struct btf_blob {
33		struct btf_header btf_hdr;
34		__u32 types[8];
35		__u32 str;
36	} raw_btf = {
37		.btf_hdr = {
38			.magic = BTF_MAGIC,
39			.version = BTF_VERSION,
40			.hdr_len = sizeof(struct btf_header),
41			.type_len = sizeof(__u32) * 8,
42			.str_off = sizeof(__u32) * 8,
43			.str_len = sizeof(__u32),
44		},
45		.types = {
46			/* long */
47			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8),  /* [1] */
48			/* unsigned long */
49			BTF_TYPE_INT_ENC(0, 0, 0, 64, 8),  /* [2] */
50		},
51	};
52	static union bpf_attr btf_load_attr = {
53		.btf_size = sizeof(raw_btf),
54	};
55
56	btf_load_attr.btf = (long)&raw_btf;
57	return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr));
58}
59
60SEC("syscall")
61int bpf_prog(struct args *ctx)
62{
63	static char license[] = "GPL";
64	static struct bpf_insn insns[] = {
65		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
66		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
67		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
68		BPF_LD_MAP_FD(BPF_REG_1, 0),
69		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
70		BPF_MOV64_IMM(BPF_REG_0, 0),
71		BPF_EXIT_INSN(),
72	};
73	static union bpf_attr map_create_attr = {
74		.map_type = BPF_MAP_TYPE_HASH,
75		.key_size = 8,
76		.value_size = 8,
77		.btf_key_type_id = 1,
78		.btf_value_type_id = 2,
79	};
80	static union bpf_attr map_update_attr = { .map_fd = 1, };
81	static __u64 key = 12;
82	static __u64 value = 34;
83	static union bpf_attr prog_load_attr = {
84		.prog_type = BPF_PROG_TYPE_XDP,
85		.insn_cnt = sizeof(insns) / sizeof(insns[0]),
86	};
87	int ret;
88
89	ret = btf_load();
90	if (ret <= 0)
91		return ret;
92
93	ctx->btf_fd = ret;
94	map_create_attr.max_entries = ctx->max_entries;
95	map_create_attr.btf_fd = ret;
96
97	prog_load_attr.license = (long) license;
98	prog_load_attr.insns = (long) insns;
99	prog_load_attr.log_buf = ctx->log_buf;
100	prog_load_attr.log_size = ctx->log_size;
101	prog_load_attr.log_level = 1;
102
103	ret = bpf_sys_bpf(BPF_MAP_CREATE, &map_create_attr, sizeof(map_create_attr));
104	if (ret <= 0)
105		return ret;
106	ctx->map_fd = ret;
107	insns[3].imm = ret;
108
109	map_update_attr.map_fd = ret;
110	map_update_attr.key = (long) &key;
111	map_update_attr.value = (long) &value;
112	ret = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, &map_update_attr, sizeof(map_update_attr));
113	if (ret < 0)
114		return ret;
115
116	ret = bpf_sys_bpf(BPF_PROG_LOAD, &prog_load_attr, sizeof(prog_load_attr));
117	if (ret <= 0)
118		return ret;
119	ctx->prog_fd = ret;
120	return 1;
121}
122