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      1 /* PPC specific symbolic name handling.
      2    Copyright (C) 2004, 2005, 2007 Red Hat, Inc.
      3    This file is part of Red Hat elfutils.
      4    Written by Ulrich Drepper <drepper (at) redhat.com>, 2004.
      5 
      6    Red Hat elfutils is free software; you can redistribute it and/or modify
      7    it under the terms of the GNU General Public License as published by the
      8    Free Software Foundation; version 2 of the License.
      9 
     10    Red Hat elfutils is distributed in the hope that it will be useful, but
     11    WITHOUT ANY WARRANTY; without even the implied warranty of
     12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13    General Public License for more details.
     14 
     15    You should have received a copy of the GNU General Public License along
     16    with Red Hat elfutils; if not, write to the Free Software Foundation,
     17    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
     18 
     19    Red Hat elfutils is an included package of the Open Invention Network.
     20    An included package of the Open Invention Network is a package for which
     21    Open Invention Network licensees cross-license their patents.  No patent
     22    license is granted, either expressly or impliedly, by designation as an
     23    included package.  Should you wish to participate in the Open Invention
     24    Network licensing program, please visit www.openinventionnetwork.com
     25    <http://www.openinventionnetwork.com>.  */
     26 
     27 #ifdef HAVE_CONFIG_H
     28 # include <config.h>
     29 #endif
     30 
     31 #include <assert.h>
     32 #include <elf.h>
     33 #include <stddef.h>
     34 #include <string.h>
     35 
     36 #define BACKEND		ppc_
     37 #include "libebl_CPU.h"
     38 
     39 
     40 /* Check for the simple reloc types.  */
     41 Elf_Type
     42 ppc_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type)
     43 {
     44   switch (type)
     45     {
     46     case R_PPC_ADDR32:
     47     case R_PPC_UADDR32:
     48       return ELF_T_WORD;
     49     case R_PPC_UADDR16:
     50       return ELF_T_HALF;
     51     default:
     52       return ELF_T_NUM;
     53     }
     54 }
     55 
     56 
     57 const char *
     58 ppc_dynamic_tag_name (int64_t tag, char *buf __attribute__ ((unused)),
     59 		      size_t len __attribute__ ((unused)))
     60 {
     61   switch (tag)
     62     {
     63     case DT_PPC_GOT:
     64       return "PPC_GOT";
     65     default:
     66       break;
     67     }
     68   return NULL;
     69 }
     70 
     71 
     72 bool
     73 ppc_dynamic_tag_check (int64_t tag)
     74 {
     75   return tag == DT_PPC_GOT;
     76 }
     77 
     78 
     79 /* Look for DT_PPC_GOT.  */
     80 static bool
     81 find_dyn_got (Elf *elf, GElf_Ehdr *ehdr, GElf_Addr *addr)
     82 {
     83   for (int i = 0; i < ehdr->e_phnum; ++i)
     84     {
     85       GElf_Phdr phdr_mem;
     86       GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
     87       if (phdr == NULL || phdr->p_type != PT_DYNAMIC)
     88 	continue;
     89 
     90       Elf_Scn *scn = gelf_offscn (elf, phdr->p_offset);
     91       GElf_Shdr shdr_mem;
     92       GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
     93       Elf_Data *data = elf_getdata (scn, NULL);
     94       if (shdr != NULL && shdr->sh_type == SHT_DYNAMIC && data != NULL)
     95 	for (unsigned int j = 0; j < shdr->sh_size / shdr->sh_entsize; ++j)
     96 	  {
     97 	    GElf_Dyn dyn_mem;
     98 	    GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem);
     99 	    if (dyn != NULL && dyn->d_tag == DT_PPC_GOT)
    100 	      {
    101 		*addr = dyn->d_un.d_ptr;
    102 		return true;
    103 	      }
    104 	  }
    105 
    106       /* There is only one PT_DYNAMIC entry.  */
    107       break;
    108     }
    109 
    110   return false;
    111 }
    112 
    113 
    114 /* Check whether given symbol's st_value and st_size are OK despite failing
    115    normal checks.  */
    116 bool
    117 ppc_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
    118 			  const char *name, const GElf_Shdr *destshdr)
    119 {
    120   if (name == NULL)
    121     return false;
    122 
    123   if (strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0)
    124     {
    125       /* In -msecure-plt mode, DT_PPC_GOT is present and must match.  */
    126       GElf_Addr gotaddr;
    127       if (find_dyn_got (elf, ehdr, &gotaddr))
    128 	return sym->st_value == gotaddr;
    129 
    130       /* In -mbss-plt mode, any place in the section is valid.  */
    131       return true;
    132     }
    133 
    134   const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
    135   if (sname == NULL)
    136     return false;
    137 
    138   if (strcmp (name, "_SDA_BASE_") == 0)
    139     return (strcmp (sname, ".sdata") == 0
    140 	    && sym->st_value == destshdr->sh_addr + 0x8000
    141 	    && sym->st_size == 0);
    142 
    143   if (strcmp (name, "_SDA2_BASE_") == 0)
    144     return (strcmp (sname, ".sdata2") == 0
    145 	    && sym->st_value == destshdr->sh_addr + 0x8000
    146 	    && sym->st_size == 0);
    147 
    148   return false;
    149 }
    150 
    151 
    152 /* Check if backend uses a bss PLT in this file.  */
    153 bool
    154 ppc_bss_plt_p (Elf *elf, GElf_Ehdr *ehdr)
    155 {
    156   GElf_Addr addr;
    157   return ! find_dyn_got (elf, ehdr, &addr);
    158 }
    159