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. */
44 Elf_Type
ppc_reloc_simple_type(Ebl * ebl,int type,int * addsub)45 ppc_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. */
62 bool
ppc_machine_flag_check(GElf_Word flags)63 ppc_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
71 const char *
ppc_dynamic_tag_name(int64_t tag,char * buf,size_t len)72 ppc_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
88 bool
ppc_dynamic_tag_check(int64_t tag)89 ppc_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. */
97 static bool
find_dyn_got(Elf * elf,GElf_Addr * addr)98 find_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. */
138 bool
ppc_check_special_symbol(Elf * elf,const GElf_Sym * sym,const char * name,const GElf_Shdr * destshdr)139 ppc_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. */
183 bool
ppc_bss_plt_p(Elf * elf)184 ppc_bss_plt_p (Elf *elf)
185 {
186 GElf_Addr addr;
187 return ! find_dyn_got (elf, &addr);
188 }
189