1//===-- DWARFDebugArangeSet.cpp ---------------------------------*- C++ -*-===//
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 "llvm/Object/Error.h"
12#include <cassert>
13
14using namespace lldb_private;
15
16DWARFDebugArangeSet::DWARFDebugArangeSet()
17    : m_offset(DW_INVALID_OFFSET), m_header(), m_arange_descriptors() {
18  m_header.length = 0;
19  m_header.version = 0;
20  m_header.cu_offset = 0;
21  m_header.addr_size = 0;
22  m_header.seg_size = 0;
23}
24
25void DWARFDebugArangeSet::Clear() {
26  m_offset = DW_INVALID_OFFSET;
27  m_header.length = 0;
28  m_header.version = 0;
29  m_header.cu_offset = 0;
30  m_header.addr_size = 0;
31  m_header.seg_size = 0;
32  m_arange_descriptors.clear();
33}
34
35llvm::Error DWARFDebugArangeSet::extract(const DWARFDataExtractor &data,
36                                         lldb::offset_t *offset_ptr) {
37  assert(data.ValidOffset(*offset_ptr));
38
39  m_arange_descriptors.clear();
40  m_offset = *offset_ptr;
41
42  // 7.20 Address Range Table
43  //
44  // Each set of entries in the table of address ranges contained in the
45  // .debug_aranges section begins with a header consisting of: a 4-byte
46  // length containing the length of the set of entries for this compilation
47  // unit, not including the length field itself; a 2-byte version identifier
48  // containing the value 2 for DWARF Version 2; a 4-byte offset into
49  // the.debug_infosection; a 1-byte unsigned integer containing the size in
50  // bytes of an address (or the offset portion of an address for segmented
51  // addressing) on the target system; and a 1-byte unsigned integer
52  // containing the size in bytes of a segment descriptor on the target
53  // system. This header is followed by a series of tuples. Each tuple
54  // consists of an address and a length, each in the size appropriate for an
55  // address on the target architecture.
56  m_header.length = data.GetDWARFInitialLength(offset_ptr);
57  m_header.version = data.GetU16(offset_ptr);
58  m_header.cu_offset = data.GetDWARFOffset(offset_ptr);
59  m_header.addr_size = data.GetU8(offset_ptr);
60  m_header.seg_size = data.GetU8(offset_ptr);
61
62  // Try to avoid reading invalid arange sets by making sure:
63  // 1 - the version looks good
64  // 2 - the address byte size looks plausible
65  // 3 - the length seems to make sense
66  // size looks plausible
67  if (m_header.version < 2 || m_header.version > 5)
68    return llvm::make_error<llvm::object::GenericBinaryError>(
69        "Invalid arange header version");
70
71  if (m_header.addr_size != 4 && m_header.addr_size != 8)
72    return llvm::make_error<llvm::object::GenericBinaryError>(
73        "Invalid arange header address size");
74
75  if (m_header.length == 0)
76    return llvm::make_error<llvm::object::GenericBinaryError>(
77        "Invalid arange header length");
78
79  if (!data.ValidOffset(m_offset + sizeof(m_header.length) + m_header.length -
80                        1))
81    return llvm::make_error<llvm::object::GenericBinaryError>(
82        "Invalid arange header length");
83
84  // The first tuple following the header in each set begins at an offset
85  // that is a multiple of the size of a single tuple (that is, twice the
86  // size of an address). The header is padded, if necessary, to the
87  // appropriate boundary.
88  const uint32_t header_size = *offset_ptr - m_offset;
89  const uint32_t tuple_size = m_header.addr_size << 1;
90  uint32_t first_tuple_offset = 0;
91  while (first_tuple_offset < header_size)
92    first_tuple_offset += tuple_size;
93
94  *offset_ptr = m_offset + first_tuple_offset;
95
96  Descriptor arangeDescriptor;
97
98  static_assert(sizeof(arangeDescriptor.address) ==
99                    sizeof(arangeDescriptor.length),
100                "DWARFDebugArangeSet::Descriptor.address and "
101                "DWARFDebugArangeSet::Descriptor.length must have same size");
102
103  while (data.ValidOffset(*offset_ptr)) {
104    arangeDescriptor.address = data.GetMaxU64(offset_ptr, m_header.addr_size);
105    arangeDescriptor.length = data.GetMaxU64(offset_ptr, m_header.addr_size);
106
107    // Each set of tuples is terminated by a 0 for the address and 0 for
108    // the length.
109    if (!arangeDescriptor.address && !arangeDescriptor.length)
110      return llvm::ErrorSuccess();
111
112    m_arange_descriptors.push_back(arangeDescriptor);
113  }
114
115  return llvm::make_error<llvm::object::GenericBinaryError>(
116      "arange descriptors not terminated by null entry");
117}
118
119class DescriptorContainsAddress {
120public:
121  DescriptorContainsAddress(dw_addr_t address) : m_address(address) {}
122  bool operator()(const DWARFDebugArangeSet::Descriptor &desc) const {
123    return (m_address >= desc.address) &&
124           (m_address < (desc.address + desc.length));
125  }
126
127private:
128  const dw_addr_t m_address;
129};
130
131dw_offset_t DWARFDebugArangeSet::FindAddress(dw_addr_t address) const {
132  DescriptorConstIter end = m_arange_descriptors.end();
133  DescriptorConstIter pos =
134      std::find_if(m_arange_descriptors.begin(), end,   // Range
135                   DescriptorContainsAddress(address)); // Predicate
136  if (pos != end)
137    return m_header.cu_offset;
138
139  return DW_INVALID_OFFSET;
140}
141