btf_sysfs.c

 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(raw_data, btf_size, 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("/sys/kernel/btf/vmlinux", NULL);
81}