1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2020 Facebook */
3 #define _GNU_SOURCE
4 #include <string.h>
5 #include <byteswap.h>
6 #include <test_progs.h>
7 #include <bpf/btf.h>
8 
9 void test_btf_endian() {
10 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
11 	enum btf_endianness endian = BTF_LITTLE_ENDIAN;
12 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
13 	enum btf_endianness endian = BTF_BIG_ENDIAN;
14 #else
15 #error "Unrecognized __BYTE_ORDER__"
16 #endif
17 	enum btf_endianness swap_endian = 1 - endian;
18 	struct btf *btf = NULL, *swap_btf = NULL;
19 	const void *raw_data, *swap_raw_data;
20 	const struct btf_type *t;
21 	const struct btf_header *hdr;
22 	__u32 raw_sz, swap_raw_sz;
23 	int var_id;
24 
25 	/* Load BTF in native endianness */
26 	btf = btf__parse_elf("btf_dump_test_case_syntax.o", NULL);
27 	if (!ASSERT_OK_PTR(btf, "parse_native_btf"))
28 		goto err_out;
29 
30 	ASSERT_EQ(btf__endianness(btf), endian, "endian");
31 	btf__set_endianness(btf, swap_endian);
32 	ASSERT_EQ(btf__endianness(btf), swap_endian, "endian");
33 
34 	/* Get raw BTF data in non-native endianness... */
35 	raw_data = btf__raw_data(btf, &raw_sz);
36 	if (!ASSERT_OK_PTR(raw_data, "raw_data_inverted"))
37 		goto err_out;
38 
39 	/* ...and open it as a new BTF instance */
40 	swap_btf = btf__new(raw_data, raw_sz);
41 	if (!ASSERT_OK_PTR(swap_btf, "parse_swap_btf"))
42 		goto err_out;
43 
44 	ASSERT_EQ(btf__endianness(swap_btf), swap_endian, "endian");
45 	ASSERT_EQ(btf__type_cnt(swap_btf), btf__type_cnt(btf), "nr_types");
46 
47 	swap_raw_data = btf__raw_data(swap_btf, &swap_raw_sz);
48 	if (!ASSERT_OK_PTR(swap_raw_data, "swap_raw_data"))
49 		goto err_out;
50 
51 	/* both raw data should be identical (with non-native endianness) */
52 	ASSERT_OK(memcmp(raw_data, swap_raw_data, raw_sz), "mem_identical");
53 
54 	/* make sure that at least BTF header data is really swapped */
55 	hdr = swap_raw_data;
56 	ASSERT_EQ(bswap_16(hdr->magic), BTF_MAGIC, "btf_magic_swapped");
57 	ASSERT_EQ(raw_sz, swap_raw_sz, "raw_sizes");
58 
59 	/* swap it back to native endianness */
60 	btf__set_endianness(swap_btf, endian);
61 	swap_raw_data = btf__raw_data(swap_btf, &swap_raw_sz);
62 	if (!ASSERT_OK_PTR(swap_raw_data, "swap_raw_data"))
63 		goto err_out;
64 
65 	/* now header should have native BTF_MAGIC */
66 	hdr = swap_raw_data;
67 	ASSERT_EQ(hdr->magic, BTF_MAGIC, "btf_magic_native");
68 	ASSERT_EQ(raw_sz, swap_raw_sz, "raw_sizes");
69 
70 	/* now modify original BTF */
71 	var_id = btf__add_var(btf, "some_var", BTF_VAR_GLOBAL_ALLOCATED, 1);
72 	ASSERT_GT(var_id, 0, "var_id");
73 
74 	btf__free(swap_btf);
75 	swap_btf = NULL;
76 
77 	btf__set_endianness(btf, swap_endian);
78 	raw_data = btf__raw_data(btf, &raw_sz);
79 	if (!ASSERT_OK_PTR(raw_data, "raw_data_inverted"))
80 		goto err_out;
81 
82 	/* and re-open swapped raw data again */
83 	swap_btf = btf__new(raw_data, raw_sz);
84 	if (!ASSERT_OK_PTR(swap_btf, "parse_swap_btf"))
85 		goto err_out;
86 
87 	ASSERT_EQ(btf__endianness(swap_btf), swap_endian, "endian");
88 	ASSERT_EQ(btf__type_cnt(swap_btf), btf__type_cnt(btf), "nr_types");
89 
90 	/* the type should appear as if it was stored in native endianness */
91 	t = btf__type_by_id(swap_btf, var_id);
92 	ASSERT_STREQ(btf__str_by_offset(swap_btf, t->name_off), "some_var", "var_name");
93 	ASSERT_EQ(btf_var(t)->linkage, BTF_VAR_GLOBAL_ALLOCATED, "var_linkage");
94 	ASSERT_EQ(t->type, 1, "var_type");
95 
96 err_out:
97 	btf__free(btf);
98 	btf__free(swap_btf);
99 }
100