1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2/* Copyright (c) 2025 Isovalent */
3
4#include <test_progs.h>
5#include <bpf/btf.h>
6#include <sys/stat.h>
7#include <sys/mman.h>
8#include <fcntl.h>
9#include <unistd.h>
10
11static void test_btf_mmap_sysfs(const char *path, struct btf *base)
12{
13 struct stat st;
14 __u64 btf_size, end;
15 void *raw_data = NULL;
16 int fd = -1;
17 long page_size;
18 struct btf *btf = NULL;
19
20 page_size = sysconf(_SC_PAGESIZE);
21 if (!ASSERT_GE(page_size, 0, "get_page_size"))
22 goto cleanup;
23
24 if (!ASSERT_OK(stat(path, &st), "stat_btf"))
25 goto cleanup;
26
27 btf_size = st.st_size;
28 end = (btf_size + page_size - 1) / page_size * page_size;
29
30 fd = open(path, O_RDONLY);
31 if (!ASSERT_GE(fd, 0, "open_btf"))
32 goto cleanup;
33
34 raw_data = mmap(NULL, btf_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
35 if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_writable"))
36 goto cleanup;
37
38 raw_data = mmap(NULL, btf_size, PROT_READ, MAP_SHARED, fd, 0);
39 if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_shared"))
40 goto cleanup;
41
42 raw_data = mmap(NULL, end + 1, PROT_READ, MAP_PRIVATE, fd, 0);
43 if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_invalid_size"))
44 goto cleanup;
45
46 raw_data = mmap(NULL, end, PROT_READ, MAP_PRIVATE, fd, 0);
47 if (!ASSERT_OK_PTR(raw_data, "mmap_btf"))
48 goto cleanup;
49
50 if (!ASSERT_EQ(mprotect(raw_data, btf_size, PROT_READ | PROT_WRITE), -1,
51 "mprotect_writable"))
52 goto cleanup;
53
54 if (!ASSERT_EQ(mprotect(raw_data, btf_size, PROT_READ | PROT_EXEC), -1,
55 "mprotect_executable"))
56 goto cleanup;
57
58 /* Check padding is zeroed */
59 for (int i = btf_size; i < end; i++) {
60 if (((__u8 *)raw_data)[i] != 0) {
61 PRINT_FAIL("tail of BTF is not zero at page offset %d\n", i);
62 goto cleanup;
63 }
64 }
65
66 btf = btf__new_split(data: raw_data, size: btf_size, base_btf: base);
67 if (!ASSERT_OK_PTR(btf, "parse_btf"))
68 goto cleanup;
69
70cleanup:
71 btf__free(btf);
72 if (raw_data && raw_data != MAP_FAILED)
73 munmap(raw_data, btf_size);
74 if (fd >= 0)
75 close(fd);
76}
77
78void test_btf_sysfs(void)
79{
80 test_btf_mmap_sysfs(path: "/sys/kernel/btf/vmlinux", NULL);
81}
82

source code of linux/tools/testing/selftests/bpf/prog_tests/btf_sysfs.c