arch/mips/tools/elf-entry.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <byteswap.h>
   3 #include <elf.h>
   4 #include <endian.h>
   5 #include <inttypes.h>
   6 #include <stdint.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <string.h>
  10
  11 #ifdef be32toh
  12 /* If libc provides [bl]e{32,64}toh() then we'll use them */
  13 #elif BYTE_ORDER == LITTLE_ENDIAN
  14 # define be32toh(x)     bswap_32(x)
  15 # define le32toh(x)     (x)
  16 # define be64toh(x)     bswap_64(x)
  17 # define le64toh(x)     (x)
  18 #elif BYTE_ORDER == BIG_ENDIAN
  19 # define be32toh(x)     (x)
  20 # define le32toh(x)     bswap_32(x)
  21 # define be64toh(x)     (x)
  22 # define le64toh(x)     bswap_64(x)
  23 #endif
  24
  25 __attribute__((noreturn))
  26 static void die(const char *msg)
  27 {
  28         fputs(msg, stderr);
  29         exit(EXIT_FAILURE);
  30 }
  31
  32 int main(int argc, const char *argv[])
  33 {
  34         uint64_t entry;
  35         size_t nread;
  36         FILE *file;
  37         union {
  38                 Elf32_Ehdr ehdr32;
  39                 Elf64_Ehdr ehdr64;
  40         } hdr;
  41
  42         if (argc != 2)
  43                 die("Usage: elf-entry <elf-file>\n");
  44
  45         file = fopen(argv[1], "r");
  46         if (!file) {
  47                 perror("Unable to open input file");
  48                 return EXIT_FAILURE;
  49         }
  50
  51         nread = fread(&hdr, 1, sizeof(hdr), file);
  52         if (nread != sizeof(hdr)) {
  53                 perror("Unable to read input file");
  54                 return EXIT_FAILURE;
  55         }
  56
  57         if (memcmp(hdr.ehdr32.e_ident, ELFMAG, SELFMAG))
  58                 die("Input is not an ELF\n");
  59
  60         switch (hdr.ehdr32.e_ident[EI_CLASS]) {
  61         case ELFCLASS32:
  62                 switch (hdr.ehdr32.e_ident[EI_DATA]) {
  63                 case ELFDATA2LSB:
  64                         entry = le32toh(hdr.ehdr32.e_entry);
  65                         break;
  66                 case ELFDATA2MSB:
  67                         entry = be32toh(hdr.ehdr32.e_entry);
  68                         break;
  69                 default:
  70                         die("Invalid ELF encoding\n");
  71                 }
  72
  73                 /* Sign extend to form a canonical address */
  74                 entry = (int64_t)(int32_t)entry;
  75                 break;
  76
  77         case ELFCLASS64:
  78                 switch (hdr.ehdr32.e_ident[EI_DATA]) {
  79                 case ELFDATA2LSB:
  80                         entry = le64toh(hdr.ehdr64.e_entry);
  81                         break;
  82                 case ELFDATA2MSB:
  83                         entry = be64toh(hdr.ehdr64.e_entry);
  84                         break;
  85                 default:
  86                         die("Invalid ELF encoding\n");
  87                 }
  88                 break;
  89
  90         default:
  91                 die("Invalid ELF class\n");
  92         }
  93
  94         printf("0x%016" PRIx64 "\n", entry);
  95         return EXIT_SUCCESS;
  96 }