1 //===-- DWARFDebugArangeSet.cpp -------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "DWARFDebugArangeSet.h"
10 #include "DWARFDataExtractor.h"
11 #include "LogChannelDWARF.h"
12 #include "llvm/Object/Error.h"
13 #include <cassert>
14
15 using namespace lldb_private;
16
DWARFDebugArangeSet()17 DWARFDebugArangeSet::DWARFDebugArangeSet()
18 : m_offset(DW_INVALID_OFFSET), m_next_offset(DW_INVALID_OFFSET) {}
19
Clear()20 void DWARFDebugArangeSet::Clear() {
21 m_offset = DW_INVALID_OFFSET;
22 m_next_offset = DW_INVALID_OFFSET;
23 m_header.length = 0;
24 m_header.version = 0;
25 m_header.cu_offset = 0;
26 m_header.addr_size = 0;
27 m_header.seg_size = 0;
28 m_arange_descriptors.clear();
29 }
30
extract(const DWARFDataExtractor & data,lldb::offset_t * offset_ptr)31 llvm::Error DWARFDebugArangeSet::extract(const DWARFDataExtractor &data,
32 lldb::offset_t *offset_ptr) {
33 assert(data.ValidOffset(*offset_ptr));
34
35 m_arange_descriptors.clear();
36 m_offset = *offset_ptr;
37
38 // 7.20 Address Range Table
39 //
40 // Each set of entries in the table of address ranges contained in the
41 // .debug_aranges section begins with a header consisting of: a 4-byte
42 // length containing the length of the set of entries for this compilation
43 // unit, not including the length field itself; a 2-byte version identifier
44 // containing the value 2 for DWARF Version 2; a 4-byte offset into
45 // the.debug_infosection; a 1-byte unsigned integer containing the size in
46 // bytes of an address (or the offset portion of an address for segmented
47 // addressing) on the target system; and a 1-byte unsigned integer
48 // containing the size in bytes of a segment descriptor on the target
49 // system. This header is followed by a series of tuples. Each tuple
50 // consists of an address and a length, each in the size appropriate for an
51 // address on the target architecture.
52 m_header.length = data.GetDWARFInitialLength(offset_ptr);
53 // The length could be 4 bytes or 12 bytes, so use the current offset to
54 // determine the next offset correctly.
55 if (m_header.length > 0)
56 m_next_offset = *offset_ptr + m_header.length;
57 else
58 m_next_offset = DW_INVALID_OFFSET;
59 m_header.version = data.GetU16(offset_ptr);
60 m_header.cu_offset = data.GetDWARFOffset(offset_ptr);
61 m_header.addr_size = data.GetU8(offset_ptr);
62 m_header.seg_size = data.GetU8(offset_ptr);
63
64 // Try to avoid reading invalid arange sets by making sure:
65 // 1 - the version looks good
66 // 2 - the address byte size looks plausible
67 // 3 - the length seems to make sense
68 // 4 - size looks plausible
69 // 5 - the arange tuples do not contain a segment field
70 if (m_header.version < 2 || m_header.version > 5)
71 return llvm::make_error<llvm::object::GenericBinaryError>(
72 "Invalid arange header version");
73
74 if (m_header.addr_size != 4 && m_header.addr_size != 8)
75 return llvm::make_error<llvm::object::GenericBinaryError>(
76 "Invalid arange header address size");
77
78 if (m_header.length == 0)
79 return llvm::make_error<llvm::object::GenericBinaryError>(
80 "Invalid arange header length");
81
82 if (!data.ValidOffset(m_offset + sizeof(m_header.length) + m_header.length -
83 1))
84 return llvm::make_error<llvm::object::GenericBinaryError>(
85 "Invalid arange header length");
86
87 if (m_header.seg_size)
88 return llvm::make_error<llvm::object::GenericBinaryError>(
89 "segmented arange entries are not supported");
90
91 // The first tuple following the header in each set begins at an offset
92 // that is a multiple of the size of a single tuple (that is, twice the
93 // size of an address). The header is padded, if necessary, to the
94 // appropriate boundary.
95 const uint32_t header_size = *offset_ptr - m_offset;
96 const uint32_t tuple_size = m_header.addr_size << 1;
97 uint32_t first_tuple_offset = 0;
98 while (first_tuple_offset < header_size)
99 first_tuple_offset += tuple_size;
100
101 *offset_ptr = m_offset + first_tuple_offset;
102
103 Descriptor arangeDescriptor;
104
105 static_assert(sizeof(arangeDescriptor.address) ==
106 sizeof(arangeDescriptor.length),
107 "DWARFDebugArangeSet::Descriptor.address and "
108 "DWARFDebugArangeSet::Descriptor.length must have same size");
109
110 const lldb::offset_t next_offset = GetNextOffset();
111 assert(next_offset != DW_INVALID_OFFSET);
112 uint32_t num_terminators = 0;
113 bool last_was_terminator = false;
114 while (*offset_ptr < next_offset) {
115 arangeDescriptor.address = data.GetMaxU64(offset_ptr, m_header.addr_size);
116 arangeDescriptor.length = data.GetMaxU64(offset_ptr, m_header.addr_size);
117
118 // Each set of tuples is terminated by a 0 for the address and 0 for
119 // the length. Some linkers can emit .debug_aranges with multiple
120 // terminator pair entries that are still withing the length of the
121 // DWARFDebugArangeSet. We want to be sure to parse all entries for
122 // this DWARFDebugArangeSet so that we don't stop parsing early and end up
123 // treating addresses as a header of the next DWARFDebugArangeSet. We also
124 // need to make sure we parse all valid address pairs so we don't omit them
125 // from the aranges result, so we can't stop at the first terminator entry
126 // we find.
127 if (arangeDescriptor.address == 0 && arangeDescriptor.length == 0) {
128 ++num_terminators;
129 last_was_terminator = true;
130 } else {
131 last_was_terminator = false;
132 // Only add .debug_aranges address entries that have a non zero size.
133 // Some linkers will zero out the length field for some .debug_aranges
134 // entries if they were stripped. We also could watch out for multiple
135 // entries at address zero and remove those as well.
136 if (arangeDescriptor.length > 0)
137 m_arange_descriptors.push_back(arangeDescriptor);
138 }
139 }
140 if (num_terminators > 1) {
141 Log *log = GetLog(DWARFLog::DebugInfo);
142 LLDB_LOG(log,
143 "warning: DWARFDebugArangeSet at %#" PRIx64 " contains %u "
144 "terminator entries",
145 m_offset, num_terminators);
146 }
147 if (last_was_terminator)
148 return llvm::ErrorSuccess();
149
150 return llvm::make_error<llvm::object::GenericBinaryError>(
151 "arange descriptors not terminated by null entry");
152 }
153
154 class DescriptorContainsAddress {
155 public:
DescriptorContainsAddress(dw_addr_t address)156 DescriptorContainsAddress(dw_addr_t address) : m_address(address) {}
operator ()(const DWARFDebugArangeSet::Descriptor & desc) const157 bool operator()(const DWARFDebugArangeSet::Descriptor &desc) const {
158 return (m_address >= desc.address) &&
159 (m_address < (desc.address + desc.length));
160 }
161
162 private:
163 const dw_addr_t m_address;
164 };
165
FindAddress(dw_addr_t address) const166 dw_offset_t DWARFDebugArangeSet::FindAddress(dw_addr_t address) const {
167 DescriptorConstIter end = m_arange_descriptors.end();
168 DescriptorConstIter pos =
169 std::find_if(m_arange_descriptors.begin(), end, // Range
170 DescriptorContainsAddress(address)); // Predicate
171 if (pos != end)
172 return m_header.cu_offset;
173
174 return DW_INVALID_OFFSET;
175 }
176