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. */
44 Elf_Type
ppc_reloc_simple_type(Ebl * ebl,int type)45 ppc_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
60 const char *
ppc_dynamic_tag_name(int64_t tag,char * buf,size_t len)61 ppc_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
75 bool
ppc_dynamic_tag_check(int64_t tag)76 ppc_dynamic_tag_check (int64_t tag)
77 {
78 return tag == DT_PPC_GOT;
79 }
80
81
82 /* Look for DT_PPC_GOT. */
83 static bool
find_dyn_got(Elf * elf,GElf_Addr * addr)84 find_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. */
123 bool
ppc_check_special_symbol(Elf * elf,GElf_Ehdr * ehdr,const GElf_Sym * sym,const char * name,const GElf_Shdr * destshdr)124 ppc_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. */
160 bool
ppc_bss_plt_p(Elf * elf)161 ppc_bss_plt_p (Elf *elf)
162 {
163 GElf_Addr addr;
164 return ! find_dyn_got (elf, &addr);
165 }
166