1/* PPC specific symbolic name handling.
2   Copyright (C) 2004, 2005, 2007, 2014, 2015 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		       int *addsub __attribute__ ((unused)))
47{
48  switch (type)
49    {
50    case R_PPC_ADDR32:
51    case R_PPC_UADDR32:
52      return ELF_T_WORD;
53    case R_PPC_UADDR16:
54      return ELF_T_HALF;
55    default:
56      return ELF_T_NUM;
57    }
58}
59
60
61/* Check whether machine flags are valid.  */
62bool
63ppc_machine_flag_check (GElf_Word flags)
64{
65  return ((flags &~ (EF_PPC_EMB
66		     | EF_PPC_RELOCATABLE
67		     | EF_PPC_RELOCATABLE_LIB)) == 0);
68}
69
70
71const char *
72ppc_dynamic_tag_name (int64_t tag, char *buf __attribute__ ((unused)),
73		      size_t len __attribute__ ((unused)))
74{
75  switch (tag)
76    {
77    case DT_PPC_GOT:
78      return "PPC_GOT";
79    case DT_PPC_OPT:
80      return "PPC_OPT";
81    default:
82      break;
83    }
84  return NULL;
85}
86
87
88bool
89ppc_dynamic_tag_check (int64_t tag)
90{
91  return (tag == DT_PPC_GOT
92	  || tag == DT_PPC_OPT);
93}
94
95
96/* Look for DT_PPC_GOT.  */
97static bool
98find_dyn_got (Elf *elf, GElf_Addr *addr)
99{
100  size_t phnum;
101  if (elf_getphdrnum (elf, &phnum) != 0)
102    return false;
103
104  for (size_t i = 0; i < phnum; ++i)
105    {
106      GElf_Phdr phdr_mem;
107      GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
108      if (phdr == NULL || phdr->p_type != PT_DYNAMIC)
109	continue;
110
111      Elf_Scn *scn = gelf_offscn (elf, phdr->p_offset);
112      GElf_Shdr shdr_mem;
113      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
114      Elf_Data *data = elf_getdata (scn, NULL);
115      if (shdr != NULL && shdr->sh_type == SHT_DYNAMIC && data != NULL
116	  && shdr->sh_entsize != 0)
117	for (unsigned int j = 0; j < shdr->sh_size / shdr->sh_entsize; ++j)
118	  {
119	    GElf_Dyn dyn_mem;
120	    GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem);
121	    if (dyn != NULL && dyn->d_tag == DT_PPC_GOT)
122	      {
123		*addr = dyn->d_un.d_ptr;
124		return true;
125	      }
126	  }
127
128      /* There is only one PT_DYNAMIC entry.  */
129      break;
130    }
131
132  return false;
133}
134
135
136/* Check whether given symbol's st_value and st_size are OK despite failing
137   normal checks.  */
138bool
139ppc_check_special_symbol (Elf *elf, const GElf_Sym *sym,
140			  const char *name, const GElf_Shdr *destshdr)
141{
142  if (name == NULL)
143    return false;
144
145  if (strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0)
146    {
147      /* In -msecure-plt mode, DT_PPC_GOT is present and must match.  */
148      GElf_Addr gotaddr;
149      if (find_dyn_got (elf, &gotaddr))
150	return sym->st_value == gotaddr;
151
152      /* In -mbss-plt mode, any place in the section is valid.  */
153      return true;
154    }
155
156  size_t shstrndx;
157  if (elf_getshdrstrndx (elf, &shstrndx) != 0)
158    return false;
159  const char *sname = elf_strptr (elf, shstrndx, destshdr->sh_name);
160  if (sname == NULL)
161    return false;
162
163  /* Small data area.  Normally points to .sdata, in which case we
164     check it is at an offset of 0x8000.  It might however fall in the
165     .data section, in which case we cannot check the offset.  The
166     size always should be zero.  */
167  if (strcmp (name, "_SDA_BASE_") == 0)
168    return (((strcmp (sname, ".sdata") == 0
169	      && sym->st_value == destshdr->sh_addr + 0x8000)
170	     || strcmp (sname, ".data") == 0)
171	    && sym->st_size == 0);
172
173  if (strcmp (name, "_SDA2_BASE_") == 0)
174    return (strcmp (sname, ".sdata2") == 0
175	    && sym->st_value == destshdr->sh_addr + 0x8000
176	    && sym->st_size == 0);
177
178  return false;
179}
180
181
182/* Check if backend uses a bss PLT in this file.  */
183bool
184ppc_bss_plt_p (Elf *elf)
185{
186  GElf_Addr addr;
187  return ! find_dyn_got (elf, &addr);
188}
189