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105 lines · 2.6 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2#ifndef _GNU_SOURCE
3#define _GNU_SOURCE
4#endif
5#include <link.h>
6#include <stdio.h>
7#include <stdlib.h>
8#include <stdbool.h>
9#include "kselftest.h"
10
11struct Statistics {
12 unsigned long long load_address;
13 unsigned long long alignment;
14 bool interp;
15};
16
17int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data)
18{
19 struct Statistics *stats = (struct Statistics *) data;
20 int i;
21
22 if (info->dlpi_name != NULL && info->dlpi_name[0] != '\0') {
23 // Ignore headers from other than the executable.
24 return 2;
25 }
26
27 stats->load_address = (unsigned long long) info->dlpi_addr;
28 stats->alignment = 0;
29
30 for (i = 0; i < info->dlpi_phnum; i++) {
31 unsigned long long align;
32
33 if (info->dlpi_phdr[i].p_type == PT_INTERP) {
34 stats->interp = true;
35 continue;
36 }
37
38 if (info->dlpi_phdr[i].p_type != PT_LOAD)
39 continue;
40
41 align = info->dlpi_phdr[i].p_align;
42
43 if (align > stats->alignment)
44 stats->alignment = align;
45 }
46
47 return 1; // Terminate dl_iterate_phdr.
48}
49
50int main(int argc, char **argv)
51{
52 struct Statistics extracted = { };
53 unsigned long long misalign, pow2;
54 bool interp_needed;
55 char buf[1024];
56 FILE *maps;
57 int ret;
58
59 ksft_print_header();
60 ksft_set_plan(4);
61
62 /* Dump maps file for debugging reference. */
63 maps = fopen("/proc/self/maps", "r");
64 if (!maps)
65 ksft_exit_fail_msg("FAILED: /proc/self/maps: %s\n", strerror(errno));
66 while (fgets(buf, sizeof(buf), maps)) {
67 ksft_print_msg("%s", buf);
68 }
69 fclose(maps);
70
71 /* Walk the program headers. */
72 ret = dl_iterate_phdr(ExtractStatistics, &extracted);
73 if (ret != 1)
74 ksft_exit_fail_msg("FAILED: dl_iterate_phdr\n");
75
76 /* Report our findings. */
77 ksft_print_msg("load_address=%#llx alignment=%#llx\n",
78 extracted.load_address, extracted.alignment);
79
80 /* If we're named with ".static." we expect no INTERP. */
81 interp_needed = strstr(argv[0], ".static.") == NULL;
82
83 /* Were we built as expected? */
84 ksft_test_result(interp_needed == extracted.interp,
85 "%s INTERP program header %s\n",
86 interp_needed ? "Wanted" : "Unwanted",
87 extracted.interp ? "seen" : "missing");
88
89 /* Did we find an alignment? */
90 ksft_test_result(extracted.alignment != 0,
91 "Alignment%s found\n", extracted.alignment ? "" : " NOT");
92
93 /* Is the alignment sane? */
94 pow2 = extracted.alignment & (extracted.alignment - 1);
95 ksft_test_result(pow2 == 0,
96 "Alignment is%s a power of 2: %#llx\n",
97 pow2 == 0 ? "" : " NOT", extracted.alignment);
98
99 /* Is the load address aligned? */
100 misalign = extracted.load_address & (extracted.alignment - 1);
101 ksft_test_result(misalign == 0, "Load Address is %saligned (%#llx)\n",
102 misalign ? "MIS" : "", misalign);
103
104 ksft_finished();
105}