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 (at) 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 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 * 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 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 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 && shdr->sh_entsize != 0) 103 for (unsigned int j = 0; j < shdr->sh_size / shdr->sh_entsize; ++j) 104 { 105 GElf_Dyn dyn_mem; 106 GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem); 107 if (dyn != NULL && dyn->d_tag == DT_PPC_GOT) 108 { 109 *addr = dyn->d_un.d_ptr; 110 return true; 111 } 112 } 113 114 /* There is only one PT_DYNAMIC entry. */ 115 break; 116 } 117 118 return false; 119 } 120 121 122 /* Check whether given symbol's st_value and st_size are OK despite failing 123 normal checks. */ 124 bool 125 ppc_check_special_symbol (Elf *elf, GElf_Ehdr *ehdr, const GElf_Sym *sym, 126 const char *name, const GElf_Shdr *destshdr) 127 { 128 if (name == NULL) 129 return false; 130 131 if (strcmp (name, "_GLOBAL_OFFSET_TABLE_") == 0) 132 { 133 /* In -msecure-plt mode, DT_PPC_GOT is present and must match. */ 134 GElf_Addr gotaddr; 135 if (find_dyn_got (elf, &gotaddr)) 136 return sym->st_value == gotaddr; 137 138 /* In -mbss-plt mode, any place in the section is valid. */ 139 return true; 140 } 141 142 const char *sname = elf_strptr (elf, ehdr->e_shstrndx, destshdr->sh_name); 143 if (sname == NULL) 144 return false; 145 146 /* Small data area. Normally points to .sdata, in which case we 147 check it is at an offset of 0x8000. It might however fall in the 148 .data section, in which case we cannot check the offset. The 149 size always should be zero. */ 150 if (strcmp (name, "_SDA_BASE_") == 0) 151 return (((strcmp (sname, ".sdata") == 0 152 && sym->st_value == destshdr->sh_addr + 0x8000) 153 || strcmp (sname, ".data") == 0) 154 && sym->st_size == 0); 155 156 if (strcmp (name, "_SDA2_BASE_") == 0) 157 return (strcmp (sname, ".sdata2") == 0 158 && sym->st_value == destshdr->sh_addr + 0x8000 159 && sym->st_size == 0); 160 161 return false; 162 } 163 164 165 /* Check if backend uses a bss PLT in this file. */ 166 bool 167 ppc_bss_plt_p (Elf *elf) 168 { 169 GElf_Addr addr; 170 return ! find_dyn_got (elf, &addr); 171 } 172
