1 /* Return DWARF attribute associated with a location expression op.
2 Copyright (C) 2013, 2014, 2017, 2018 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 <dwarf.h>
34 #include <libdwP.h>
35
36 static Dwarf_CU *
attr_form_cu(Dwarf_Attribute * attr)37 attr_form_cu (Dwarf_Attribute *attr)
38 {
39 /* If the attribute has block/expr form the data comes from the
40 .debug_info from the same cu as the attr. Otherwise it comes from
41 the .debug_loc or .debug_loclists data section. */
42 switch (attr->form)
43 {
44 case DW_FORM_block1:
45 case DW_FORM_block2:
46 case DW_FORM_block4:
47 case DW_FORM_block:
48 case DW_FORM_exprloc:
49 return attr->cu;
50 default:
51 return (attr->cu->version < 5
52 ? attr->cu->dbg->fake_loc_cu
53 : attr->cu->dbg->fake_loclists_cu);
54 }
55 }
56
57 static unsigned char *
addr_valp(Dwarf_CU * cu,Dwarf_Word index)58 addr_valp (Dwarf_CU *cu, Dwarf_Word index)
59 {
60 Elf_Data *debug_addr = cu->dbg->sectiondata[IDX_debug_addr];
61 if (debug_addr == NULL)
62 {
63 __libdw_seterrno (DWARF_E_NO_DEBUG_ADDR);
64 return NULL;
65 }
66
67 Dwarf_Word offset = __libdw_cu_addr_base (cu) + (index * cu->address_size);
68 return (unsigned char *) debug_addr->d_buf + offset;
69 }
70
71 int
dwarf_getlocation_attr(Dwarf_Attribute * attr,const Dwarf_Op * op,Dwarf_Attribute * result)72 dwarf_getlocation_attr (Dwarf_Attribute *attr, const Dwarf_Op *op, Dwarf_Attribute *result)
73 {
74 if (attr == NULL)
75 return -1;
76
77 switch (op->atom)
78 {
79 case DW_OP_implicit_value:
80 result->code = DW_AT_const_value;
81 result->form = DW_FORM_block;
82 result->valp = (unsigned char *) (uintptr_t) op->number2;
83 result->cu = attr_form_cu (attr);
84 break;
85
86 case DW_OP_entry_value:
87 case DW_OP_GNU_entry_value:
88 result->code = DW_AT_location;
89 result->form = DW_FORM_exprloc;
90 result->valp = (unsigned char *) (uintptr_t) op->number2;
91 result->cu = attr_form_cu (attr);
92 break;
93
94 case DW_OP_const_type:
95 case DW_OP_GNU_const_type:
96 result->code = DW_AT_const_value;
97 result->form = DW_FORM_block1;
98 result->valp = (unsigned char *) (uintptr_t) op->number2;
99 result->cu = attr_form_cu (attr);
100 break;
101
102 case DW_OP_GNU_const_index:
103 case DW_OP_constx:
104 result->code = DW_AT_const_value;
105 if (attr->cu->address_size == 4)
106 result->form = DW_FORM_data4;
107 else
108 result->form = DW_FORM_data8;
109 result->valp = addr_valp (attr->cu, op->number);
110 if (result->valp == NULL)
111 return -1;
112 result->cu = attr->cu->dbg->fake_addr_cu;
113 break;
114
115 case DW_OP_GNU_addr_index:
116 case DW_OP_addrx:
117 result->code = DW_AT_low_pc;
118 result->form = DW_FORM_addr;
119 result->valp = addr_valp (attr->cu, op->number);
120 if (result->valp == NULL)
121 return -1;
122 result->cu = attr->cu->dbg->fake_addr_cu;
123 break;
124
125 case DW_OP_call2:
126 case DW_OP_call4:
127 case DW_OP_call_ref:
128 {
129 Dwarf_Die die;
130 if (INTUSE(dwarf_getlocation_die) (attr, op, &die) != 0)
131 return -1;
132 if (INTUSE(dwarf_attr) (&die, DW_AT_location, result) == NULL)
133 {
134 __libdw_empty_loc_attr (result);
135 return 0;
136 }
137 }
138 break;
139
140 case DW_OP_implicit_pointer:
141 case DW_OP_GNU_implicit_pointer:
142 case DW_OP_GNU_variable_value:
143 {
144 Dwarf_Die die;
145 if (INTUSE(dwarf_getlocation_die) (attr, op, &die) != 0)
146 return -1;
147 if (INTUSE(dwarf_attr) (&die, DW_AT_location, result) == NULL
148 && INTUSE(dwarf_attr) (&die, DW_AT_const_value, result) == NULL)
149 {
150 __libdw_empty_loc_attr (result);
151 return 0;
152 }
153 }
154 break;
155
156 default:
157 __libdw_seterrno (DWARF_E_INVALID_ACCESS);
158 return -1;
159 }
160
161 return 0;
162 }
163