1 /* DW_EH_PE_* support for libdw unwinder. 2 Copyright (C) 2009-2010, 2014 Red Hat, Inc. 3 This file is part of elfutils. 4 5 This file is free software; you can redistribute it and/or modify 6 it under the terms of either 7 8 * the GNU Lesser General Public License as published by the Free 9 Software Foundation; either version 3 of the License, or (at 10 your option) any later version 11 12 or 13 14 * the GNU General Public License as published by the Free 15 Software Foundation; either version 2 of the License, or (at 16 your option) any later version 17 18 or both in parallel, as here. 19 20 elfutils is distributed in the hope that it will be useful, but 21 WITHOUT ANY WARRANTY; without even the implied warranty of 22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 23 General Public License for more details. 24 25 You should have received copies of the GNU General Public License and 26 the GNU Lesser General Public License along with this program. If 27 not, see <http://www.gnu.org/licenses/>. */ 28 29 #ifndef _ENCODED_VALUE_H 30 #define _ENCODED_VALUE_H 1 31 32 #include <dwarf.h> 33 #include <stdlib.h> 34 #include "libdwP.h" 35 36 37 static size_t __attribute__ ((unused)) 38 encoded_value_size (const Elf_Data *data, const unsigned char e_ident[], 39 uint8_t encoding, const uint8_t *p) 40 { 41 if (encoding == DW_EH_PE_omit) 42 return 0; 43 44 switch (encoding & 0x07) 45 { 46 case DW_EH_PE_udata2: 47 return 2; 48 case DW_EH_PE_udata4: 49 return 4; 50 case DW_EH_PE_udata8: 51 return 8; 52 53 case DW_EH_PE_absptr: 54 return e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; 55 56 case DW_EH_PE_uleb128: 57 if (p != NULL) 58 { 59 const uint8_t *end = p; 60 while (end < (uint8_t *) data->d_buf + data->d_size) 61 if (*end++ & 0x80u) 62 return end - p; 63 } 64 65 default: 66 abort (); 67 return 0; 68 } 69 } 70 71 static inline int __attribute__ ((unused)) 72 __libdw_cfi_read_address_inc (const Dwarf_CFI *cache, 73 const unsigned char **addrp, 74 int width, Dwarf_Addr *ret) 75 { 76 width = width ?: cache->e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; 77 78 if (cache->dbg != NULL) 79 return __libdw_read_address_inc (cache->dbg, IDX_debug_frame, 80 addrp, width, ret); 81 82 /* Only .debug_frame might have relocation to consider. 83 Read plain values from .eh_frame data. */ 84 85 if (width == 4) 86 *ret = read_4ubyte_unaligned_inc (cache, *addrp); 87 else 88 *ret = read_8ubyte_unaligned_inc (cache, *addrp); 89 return 0; 90 } 91 92 static bool __attribute__ ((unused)) 93 read_encoded_value (const Dwarf_CFI *cache, uint8_t encoding, const uint8_t **p, 94 Dwarf_Addr *result) 95 { 96 *result = 0; 97 switch (encoding & 0x70) 98 { 99 case DW_EH_PE_absptr: 100 break; 101 case DW_EH_PE_pcrel: 102 *result = (cache->frame_vaddr 103 + (*p - (const uint8_t *) cache->data->d.d_buf)); 104 break; 105 case DW_EH_PE_textrel: 106 // ia64: segrel 107 *result = cache->textrel; 108 break; 109 case DW_EH_PE_datarel: 110 // i386: GOTOFF 111 // ia64: gprel 112 *result = cache->datarel; 113 break; 114 case DW_EH_PE_funcrel: /* XXX */ 115 break; 116 case DW_EH_PE_aligned: 117 { 118 const size_t size = encoded_value_size (&cache->data->d, cache->e_ident, 119 encoding, *p); 120 size_t align = ((cache->frame_vaddr 121 + (*p - (const uint8_t *) cache->data->d.d_buf)) 122 & (size - 1)); 123 if (align != 0) 124 *p += size - align; 125 break; 126 } 127 128 default: 129 abort (); 130 } 131 132 Dwarf_Addr value; 133 switch (encoding & 0x0f) 134 { 135 case DW_EH_PE_udata2: 136 value = read_2ubyte_unaligned_inc (cache, *p); 137 break; 138 139 case DW_EH_PE_sdata2: 140 value = read_2sbyte_unaligned_inc (cache, *p); 141 break; 142 143 case DW_EH_PE_udata4: 144 if (__libdw_cfi_read_address_inc (cache, p, 4, &value)) 145 return true; 146 break; 147 148 case DW_EH_PE_sdata4: 149 if (__libdw_cfi_read_address_inc (cache, p, 4, &value)) 150 return true; 151 value = (Dwarf_Sword) (Elf32_Sword) value; /* Sign-extend. */ 152 break; 153 154 case DW_EH_PE_udata8: 155 case DW_EH_PE_sdata8: 156 if (__libdw_cfi_read_address_inc (cache, p, 8, &value)) 157 return true; 158 break; 159 160 case DW_EH_PE_absptr: 161 if (__libdw_cfi_read_address_inc (cache, p, 0, &value)) 162 return true; 163 break; 164 165 case DW_EH_PE_uleb128: 166 // XXX we trust there is enough data. 167 get_uleb128 (value, *p, *p + len_leb128 (Dwarf_Addr)); 168 break; 169 170 case DW_EH_PE_sleb128: 171 // XXX we trust there is enough data. 172 get_sleb128 (value, *p, *p + len_leb128 (Dwarf_Addr)); 173 break; 174 175 default: 176 abort (); 177 } 178 179 *result += value; 180 181 if (encoding & DW_EH_PE_indirect) 182 { 183 if (unlikely (*result < cache->frame_vaddr)) 184 return true; 185 *result -= cache->frame_vaddr; 186 if (unlikely (*result > (cache->data->d.d_size 187 - encoded_value_size (NULL, cache->e_ident, 188 DW_EH_PE_absptr, NULL)))) 189 return true; 190 const uint8_t *ptr = cache->data->d.d_buf + *result; 191 return __libdw_cfi_read_address_inc (cache, &ptr, 0, result); 192 } 193 194 return false; 195 } 196 197 #endif /* encoded-value.h */ 198
