1/* PPC specific symbolic name handling.
2   Copyright (C) 2004, 2005, 2007, 2014 Red Hat, Inc.
3   This file is part of elfutils.
4   Written by Ulrich Drepper <drepper@redhat.com>, 2004.
5
6   This file is free software; you can redistribute it and/or modify
7   it under the terms of either
8
9     * the GNU Lesser General Public License as published by the Free
10       Software Foundation; either version 3 of the License, or (at
11       your option) any later version
12
13   or
14
15     * the GNU General Public License as published by the Free
16       Software Foundation; either version 2 of the License, or (at
17       your option) any later version
18
19   or both in parallel, as here.
20
21   elfutils is distributed in the hope that it will be useful, but
22   WITHOUT ANY WARRANTY; without even the implied warranty of
23   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
24   General Public License for more details.
25
26   You should have received copies of the GNU General Public License and
27   the GNU Lesser General Public License along with this program.  If
28   not, see <http://www.gnu.org/licenses/>.  */
29
30#ifdef HAVE_CONFIG_H
31# include <config.h>
32#endif
33
34#include <assert.h>
35#include <elf.h>
36#include <stddef.h>
37#include <string.h>
38
39#define BACKEND		ppc_
40#include "libebl_CPU.h"
41
42
43/* Check for the simple reloc types.  */
44Elf_Type
45ppc_reloc_simple_type (Ebl *ebl __attribute__ ((unused)), int type)
46{
47  switch (type)
48    {
49    case R_PPC_ADDR32:
50    case R_PPC_UADDR32:
51      return ELF_T_WORD;
52    case R_PPC_UADDR16:
53      return ELF_T_HALF;
54    default:
55      return ELF_T_NUM;
56    }
57}
58
59
60const char *
61ppc_dynamic_tag_name (int64_t tag, char *buf __attribute__ ((unused)),
62		      size_t len __attribute__ ((unused)))
63{
64  switch (tag)
65    {
66    case DT_PPC_GOT:
67      return "PPC_GOT";
68    default:
69      break;
70    }
71  return NULL;
72}
73
74
75bool
76ppc_dynamic_tag_check (int64_t tag)
77{
78  return tag == DT_PPC_GOT;
79}
80
81
82/* Look for DT_PPC_GOT.  */
83static bool
84find_dyn_got (Elf *elf, GElf_Addr *addr)
85{
86  size_t phnum;
87  if (elf_getphdrnum (elf, &phnum) != 0)
88    return false;
89
90  for (size_t i = 0; i < phnum; ++i)
91    {
92      GElf_Phdr phdr_mem;
93      GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
94      if (phdr == NULL || phdr->p_type != PT_DYNAMIC)
95	continue;
96
97      Elf_Scn *scn = gelf_offscn (elf, phdr->p_offset);
98      GElf_Shdr shdr_mem;
99      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
100      Elf_Data *data = elf_getdata (scn, NULL);
101      if (shdr != NULL && shdr->sh_type == SHT_DYNAMIC && data != NULL)
102	for (unsigned int j = 0; j < shdr->sh_size / shdr->sh_entsize; ++j)
103	  {
104	    GElf_Dyn dyn_mem;
105	    GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem);
106	    if (dyn != NULL && dyn->d_tag == DT_PPC_GOT)
107	      {
108		*addr = dyn->d_un.d_ptr;
109		return true;
110	      }
111	  }
112
113      /* There is only one PT_DYNAMIC entry.  */
114      break;
115    }
116
117  return false;
118}
119
120
121/* Check whether given symbol's st_value and st_size are OK despite failing
122   normal checks.  */
123bool
124ppc_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym,
125			  const char *name, const GElf_Shdr *destshdr)
126{
127  if (name == NULL)
128    return false;
129
130  if (strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0)
131    {
132      /* In -msecure-plt mode, DT_PPC_GOT is present and must match.  */
133      GElf_Addr gotaddr;
134      if (find_dyn_got (elf, &gotaddr))
135	return sym->st_value == gotaddr;
136
137      /* In -mbss-plt mode, any place in the section is valid.  */
138      return true;
139    }
140
141  const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name);
142  if (sname == NULL)
143    return false;
144
145  if (strcmp (name, "_SDA_BASE_") == 0)
146    return (strcmp (sname, ".sdata") == 0
147	    && sym->st_value == destshdr->sh_addr + 0x8000
148	    && sym->st_size == 0);
149
150  if (strcmp (name, "_SDA2_BASE_") == 0)
151    return (strcmp (sname, ".sdata2") == 0
152	    && sym->st_value == destshdr->sh_addr + 0x8000
153	    && sym->st_size == 0);
154
155  return false;
156}
157
158
159/* Check if backend uses a bss PLT in this file.  */
160bool
161ppc_bss_plt_p (Elf *elf)
162{
163  GElf_Addr addr;
164  return ! find_dyn_got (elf, &addr);
165}
166