tools/testing/selftests/exec/load_address.c

   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
  11 struct Statistics {
  12         unsigned long long load_address;
  13         unsigned long long alignment;
  14         bool interp;
  15 };
  16
  17 int 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
  50 int 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 }