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 
14 using namespace lldb_private;
15 
16 DWARFDebugArangeSet::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 
25 void 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 
35 llvm::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 
119 class DescriptorContainsAddress {
120 public:
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 
127 private:
128   const dw_addr_t m_address;
129 };
130 
131 dw_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