1 /* DW_EH_PE_* support for libdw unwinder. 2 Copyright (C) 2009-2010, 2014, 2015 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 #include "../libelf/common.h" 36 37 38 /* Returns zero if the value is omitted, the encoding is unknown or 39 the (leb128) size cannot be determined. */ 40 static size_t __attribute__ ((unused)) 41 encoded_value_size (const Elf_Data *data, const unsigned char e_ident[], 42 uint8_t encoding, const uint8_t *p) 43 { 44 if (encoding == DW_EH_PE_omit) 45 return 0; 46 47 switch (encoding & 0x07) 48 { 49 case DW_EH_PE_udata2: 50 return 2; 51 case DW_EH_PE_udata4: 52 return 4; 53 case DW_EH_PE_udata8: 54 return 8; 55 56 case DW_EH_PE_absptr: 57 return e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; 58 59 case DW_EH_PE_uleb128: 60 if (p != NULL) 61 { 62 const uint8_t *end = p; 63 while (end < (uint8_t *) data->d_buf + data->d_size) 64 if (*end++ & 0x80u) 65 return end - p; 66 } 67 return 0; 68 69 default: 70 return 0; 71 } 72 } 73 74 /* Returns zero when value was read successfully, minus one otherwise. */ 75 static inline int __attribute__ ((unused)) 76 __libdw_cfi_read_address_inc (const Dwarf_CFI *cache, 77 const unsigned char **addrp, 78 int width, Dwarf_Addr *ret) 79 { 80 width = width ?: cache->e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8; 81 82 if (cache->dbg != NULL) 83 return __libdw_read_address_inc (cache->dbg, IDX_debug_frame, 84 addrp, width, ret); 85 86 /* Only .debug_frame might have relocation to consider. 87 Read plain values from .eh_frame data. */ 88 89 const unsigned char *endp = cache->data->d.d_buf + cache->data->d.d_size; 90 Dwarf eh_dbg = { .other_byte_order = MY_ELFDATA != cache->e_ident[EI_DATA] }; 91 92 if (width == 4) 93 { 94 if (unlikely (*addrp + 4 > endp)) 95 { 96 invalid_data: 97 __libdw_seterrno (DWARF_E_INVALID_CFI); 98 return -1; 99 } 100 *ret = read_4ubyte_unaligned_inc (&eh_dbg, *addrp); 101 } 102 else 103 { 104 if (unlikely (*addrp + 8 > endp)) 105 goto invalid_data; 106 *ret = read_8ubyte_unaligned_inc (&eh_dbg, *addrp); 107 } 108 return 0; 109 } 110 111 /* Returns true on error, false otherwise. */ 112 static bool __attribute__ ((unused)) 113 read_encoded_value (const Dwarf_CFI *cache, uint8_t encoding, 114 const uint8_t **p, Dwarf_Addr *result) 115 { 116 *result = 0; 117 switch (encoding & 0x70) 118 { 119 case DW_EH_PE_absptr: 120 break; 121 case DW_EH_PE_pcrel: 122 *result = (cache->frame_vaddr 123 + (*p - (const uint8_t *) cache->data->d.d_buf)); 124 break; 125 case DW_EH_PE_textrel: 126 // ia64: segrel 127 *result = cache->textrel; 128 break; 129 case DW_EH_PE_datarel: 130 // i386: GOTOFF 131 // ia64: gprel 132 *result = cache->datarel; 133 break; 134 case DW_EH_PE_funcrel: /* XXX */ 135 break; 136 case DW_EH_PE_aligned: 137 { 138 const size_t size = encoded_value_size (&cache->data->d, 139 cache->e_ident, 140 encoding, *p); 141 if (unlikely (size == 0)) 142 return true; 143 size_t align = ((cache->frame_vaddr 144 + (*p - (const uint8_t *) cache->data->d.d_buf)) 145 & (size - 1)); 146 if (align != 0) 147 *p += size - align; 148 break; 149 } 150 151 default: 152 __libdw_seterrno (DWARF_E_INVALID_CFI); 153 return true; 154 } 155 156 Dwarf_Addr value = 0; 157 const unsigned char *endp = cache->data->d.d_buf + cache->data->d.d_size; 158 switch (encoding & 0x0f) 159 { 160 case DW_EH_PE_udata2: 161 if (unlikely (*p + 2 > endp)) 162 { 163 invalid_data: 164 __libdw_seterrno (DWARF_E_INVALID_CFI); 165 return true; 166 } 167 value = read_2ubyte_unaligned_inc (cache, *p); 168 break; 169 170 case DW_EH_PE_sdata2: 171 if (unlikely (*p + 2 > endp)) 172 goto invalid_data; 173 value = read_2sbyte_unaligned_inc (cache, *p); 174 break; 175 176 case DW_EH_PE_udata4: 177 if (unlikely (__libdw_cfi_read_address_inc (cache, p, 4, &value) != 0)) 178 return true; 179 break; 180 181 case DW_EH_PE_sdata4: 182 if (unlikely (__libdw_cfi_read_address_inc (cache, p, 4, &value) != 0)) 183 return true; 184 value = (Dwarf_Sword) (Elf32_Sword) value; /* Sign-extend. */ 185 break; 186 187 case DW_EH_PE_udata8: 188 case DW_EH_PE_sdata8: 189 if (unlikely (__libdw_cfi_read_address_inc (cache, p, 8, &value) != 0)) 190 return true; 191 break; 192 193 case DW_EH_PE_absptr: 194 if (unlikely (__libdw_cfi_read_address_inc (cache, p, 0, &value) != 0)) 195 return true; 196 break; 197 198 case DW_EH_PE_uleb128: 199 get_uleb128 (value, *p, endp); 200 break; 201 202 case DW_EH_PE_sleb128: 203 get_sleb128 (value, *p, endp); 204 break; 205 206 default: 207 __libdw_seterrno (DWARF_E_INVALID_CFI); 208 return true; 209 } 210 211 *result += value; 212 213 if (encoding & DW_EH_PE_indirect) 214 { 215 if (unlikely (*result < cache->frame_vaddr)) 216 return true; 217 *result -= cache->frame_vaddr; 218 size_t ptrsize = encoded_value_size (NULL, cache->e_ident, 219 DW_EH_PE_absptr, NULL); 220 if (unlikely (cache->data->d.d_size < ptrsize 221 || *result > (cache->data->d.d_size - ptrsize))) 222 return true; 223 const uint8_t *ptr = cache->data->d.d_buf + *result; 224 if (unlikely (__libdw_cfi_read_address_inc (cache, &ptr, 0, result) 225 != 0)) 226 return true; 227 } 228 229 return false; 230 } 231 232 #endif /* encoded-value.h */ 233
