kern/powerpc/dl.c

   1 /* dl.c - arch-dependent part of loadable module support */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2004,2005,2007  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/dl.h>
  21 #include <grub/elf.h>
  22 #include <grub/misc.h>
  23 #include <grub/err.h>
  24
  25 /* Check if EHDR is a valid ELF header.  */
  26 grub_err_t
  27 grub_arch_dl_check_header (void *ehdr)
  28 {
  29   Elf32_Ehdr *e = ehdr;
  30
  31   /* Check the magic numbers.  */
  32   if (e->e_ident[EI_CLASS] != ELFCLASS32
  33       || e->e_ident[EI_DATA] != ELFDATA2MSB
  34       || e->e_machine != EM_PPC)
  35     return grub_error (GRUB_ERR_BAD_OS, "invalid arch specific ELF magic");
  36
  37   return GRUB_ERR_NONE;
  38 }
  39
  40
  41 /* Relocate symbols.  */
  42 grub_err_t
  43 grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr)
  44 {
  45   Elf32_Ehdr *e = ehdr;
  46   Elf32_Shdr *s;
  47   Elf32_Sym *symtab;
  48   Elf32_Word entsize;
  49   unsigned i;
  50
  51   /* Find a symbol table.  */
  52   for (i = 0, s = (Elf32_Shdr *) ((char *) e + e->e_shoff);
  53        i < e->e_shnum;
  54        i++, s = (Elf32_Shdr *) ((char *) s + e->e_shentsize))
  55     if (s->sh_type == SHT_SYMTAB)
  56       break;
  57
  58   if (i == e->e_shnum)
  59     return grub_error (GRUB_ERR_BAD_MODULE, "no symtab found");
  60
  61   symtab = (Elf32_Sym *) ((char *) e + s->sh_offset);
  62   entsize = s->sh_entsize;
  63
  64   for (i = 0, s = (Elf32_Shdr *) ((char *) e + e->e_shoff);
  65        i < e->e_shnum;
  66        i++, s = (Elf32_Shdr *) ((char *) s + e->e_shentsize))
  67     if (s->sh_type == SHT_RELA)
  68       {
  69         grub_dl_segment_t seg;
  70
  71         /* Find the target segment.  */
  72         for (seg = mod->segment; seg; seg = seg->next)
  73           if (seg->section == s->sh_info)
  74             break;
  75
  76         if (seg)
  77           {
  78             Elf32_Rela *rel, *max;
  79
  80             for (rel = (Elf32_Rela *) ((char *) e + s->sh_offset),
  81                    max = rel + s->sh_size / s->sh_entsize;
  82                  rel < max;
  83                  rel++)
  84               {
  85                 Elf32_Word *addr;
  86                 Elf32_Sym *sym;
  87                 grub_uint32_t value;
  88
  89                 if (seg->size < rel->r_offset)
  90                   return grub_error (GRUB_ERR_BAD_MODULE,
  91                                      "reloc offset is out of the segment");
  92
  93                 addr = (Elf32_Word *) ((char *) seg->addr + rel->r_offset);
  94                 sym = (Elf32_Sym *) ((char *) symtab
  95                                      + entsize * ELF32_R_SYM (rel->r_info));
  96
  97                 /* On the PPC the value does not have an explicit
  98                    addend, add it.  */
  99                 value = sym->st_value + rel->r_addend;
 100                 switch (ELF32_R_TYPE (rel->r_info))
 101                   {
 102                   case R_PPC_ADDR16_LO:
 103                     *(Elf32_Half *) addr = value;
 104                     break;
 105
 106                   case R_PPC_REL24:
 107                     {
 108                       Elf32_Sword delta = value - (Elf32_Word) addr;
 109
 110                       if (delta << 6 >> 6 != delta)
 111                         return grub_error (GRUB_ERR_BAD_MODULE, "Relocation overflow");
 112                       *addr = (*addr & 0xfc000003) | (delta & 0x3fffffc);
 113                       break;
 114                     }
 115
 116                   case R_PPC_ADDR16_HA:
 117                     *(Elf32_Half *) addr = (value + 0x8000) >> 16;
 118                     break;
 119
 120                   case R_PPC_ADDR32:
 121                     *addr = value;
 122                     break;
 123
 124                   case R_PPC_REL32:
 125                     *addr = value - (Elf32_Word) addr;
 126                     break;
 127
 128                   default:
 129                     return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
 130                                        "This relocation (%d) is not implemented yet",
 131                                        ELF32_R_TYPE (rel->r_info));
 132                   }
 133               }
 134           }
 135       }
 136
 137   return GRUB_ERR_NONE;
 138 }