1 /* Get register location expression for frame. 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 #ifdef HAVE_CONFIG_H 30 # include <config.h> 31 #endif 32 33 #include "cfi.h" 34 #include <dwarf.h> 35 36 int 37 dwarf_frame_register (fs, regno, ops_mem, ops, nops) 38 Dwarf_Frame *fs; 39 int regno; 40 Dwarf_Op ops_mem[3]; 41 Dwarf_Op **ops; 42 size_t *nops; 43 { 44 /* Maybe there was a previous error. */ 45 if (fs == NULL) 46 return -1; 47 48 if (unlikely (regno < 0)) 49 { 50 __libdw_seterrno (DWARF_E_INVALID_ACCESS); 51 return -1; 52 } 53 54 *ops = ops_mem; 55 *nops = 0; 56 57 if (unlikely ((size_t) regno >= fs->nregs)) 58 goto default_rule; 59 60 const struct dwarf_frame_register *reg = &fs->regs[regno]; 61 62 switch (reg->rule) 63 { 64 case reg_unspecified: 65 default_rule: 66 /* Use the default rule for registers not yet mentioned in CFI. */ 67 if (fs->cache->default_same_value) 68 goto same_value; 69 /*FALLTHROUGH*/ 70 case reg_undefined: 71 /* The value is known to be unavailable. */ 72 break; 73 74 case reg_same_value: 75 same_value: 76 /* The location is not known here, but the caller might know it. */ 77 *ops = NULL; 78 break; 79 80 case reg_offset: 81 case reg_val_offset: 82 ops_mem[(*nops)++] = (Dwarf_Op) { .atom = DW_OP_call_frame_cfa }; 83 if (reg->value != 0) 84 ops_mem[(*nops)++] = (Dwarf_Op) { .atom = DW_OP_plus_uconst, 85 .number = reg->value }; 86 if (reg->rule == reg_val_offset) 87 /* A value, not a location. */ 88 ops_mem[(*nops)++] = (Dwarf_Op) { .atom = DW_OP_stack_value }; 89 *ops = ops_mem; 90 break; 91 92 case reg_register: 93 ops_mem[(*nops)++] = (Dwarf_Op) { .atom = DW_OP_regx, 94 .number = reg->value }; 95 break; 96 97 case reg_val_expression: 98 case reg_expression: 99 { 100 unsigned int address_size = (fs->cache->e_ident[EI_CLASS] == ELFCLASS32 101 ? 4 : 8); 102 103 Dwarf_Block block; 104 const uint8_t *p = fs->cache->data->d.d_buf + reg->value; 105 const uint8_t *end = (fs->cache->data->d.d_buf 106 + fs->cache->data->d.d_size); 107 get_uleb128 (block.length, p, end); 108 block.data = (void *) p; 109 110 /* Parse the expression into internal form. */ 111 if (__libdw_intern_expression (NULL, 112 fs->cache->other_byte_order, 113 address_size, 4, 114 &fs->cache->expr_tree, &block, 115 true, reg->rule == reg_val_expression, 116 ops, nops, IDX_debug_frame) < 0) 117 return -1; 118 break; 119 } 120 } 121 122 return 0; 123 } 124
