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LibDebug: Parse DWARF information entries

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We can now iterate the tree structure of the DIEs, access attribute
values and parse some very basic DWARF expressions.
This commit is contained in:
Itamar 2020-05-04 12:14:39 +03:00 • committed by Andreas Kling
parent 2cafc36d9c
commit c5eb20d0cc
14 changed files with 1067 additions and 3 deletions
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204
Libraries/LibDebug/Dwarf/DIE.cpp Normal file
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/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "DIE.h"
#include "CompilationUnit.h"
#include "DwarfInfo.h"
#include <AK/BufferStream.h>
#include <AK/ByteBuffer.h>
namespace Dwarf {
DIE::DIE(const CompilationUnit& unit, u32 offset)
: m_compilation_unit(unit)
, m_offset(offset)
{
BufferStream stream(const_cast<ByteBuffer&>(m_compilation_unit.dwarf_info().debug_info_data()));
stream.advance(m_offset);
stream.read_LEB128_unsigned(m_abbreviation_code);
m_data_offset = stream.offset();
if (m_abbreviation_code == 0) {
// An abbrevation code of 0 ( = null DIE entry) means the end of a chain of sibilings
m_tag = EntryTag::None;
} else {
auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
ASSERT(abbreviation_info.has_value());
m_tag = abbreviation_info.value().tag;
m_has_children = abbreviation_info.value().has_children;
// We iterate the attributes data only to calculate this DIE's size
for (auto attribute_spec : abbreviation_info.value().attribute_specifications) {
get_attribute_value(attribute_spec.form, stream);
}
}
m_size = stream.offset() - m_offset;
}
DIE::AttributeValue DIE::get_attribute_value(AttributeDataForm form,
BufferStream& debug_info_stream) const
{
AttributeValue value;
switch (form) {
case AttributeDataForm::StringPointer: {
u32 offset = 0;
debug_info_stream >> offset;
value.type = AttributeValue::Type::String;
auto strings_data = m_compilation_unit.dwarf_info().debug_strings_data();
value.data.as_string = reinterpret_cast<const char*>(strings_data.data() + offset);
break;
}
case AttributeDataForm::Data1: {
u8 data = 0;
debug_info_stream >> data;
value.type = AttributeValue::Type::UnsignedNumber;
value.data.as_u32 = data;
break;
}
case AttributeDataForm::Data2: {
u16 data = 0;
debug_info_stream >> data;
value.type = AttributeValue::Type::UnsignedNumber;
value.data.as_u32 = data;
break;
}
case AttributeDataForm::Addr: {
u32 address = 0;
debug_info_stream >> address;
value.type = AttributeValue::Type::UnsignedNumber;
value.data.as_u32 = address;
break;
}
case AttributeDataForm::SecOffset: {
u32 data = 0;
debug_info_stream >> data;
value.type = AttributeValue::Type::SecOffset;
value.data.as_u32 = data;
break;
}
case AttributeDataForm::Data4: {
u32 data = 0;
debug_info_stream >> data;
value.type = AttributeValue::Type::UnsignedNumber;
value.data.as_u32 = data;
break;
}
case AttributeDataForm::Ref4: {
u32 data = 0;
debug_info_stream >> data;
value.type = AttributeValue::Type::DieReference;
value.data.as_u32 = data + m_compilation_unit.offset();
break;
}
case AttributeDataForm::FlagPresent: {
value.type = AttributeValue::Type::Boolean;
value.data.as_bool = true;
break;
}
case AttributeDataForm::ExprLoc: {
size_t length = 0;
debug_info_stream.read_LEB128_unsigned(length);
value.type = AttributeValue::Type::DwarfExpression;
value.data.as_dwarf_expression.length = length;
value.data.as_dwarf_expression.bytes = reinterpret_cast<const u8*>(m_compilation_unit.dwarf_info().debug_info_data().data() + debug_info_stream.offset());
debug_info_stream.advance(length);
break;
}
case AttributeDataForm::String: {
String str;
u32 str_offset = debug_info_stream.offset();
debug_info_stream >> str;
value.type = AttributeValue::Type::String;
value.data.as_string = reinterpret_cast<const char*>(str_offset + m_compilation_unit.dwarf_info().debug_info_data().data());
break;
}
default:
dbg() << "Unimplemented AttributeDataForm: " << (u32)form;
ASSERT_NOT_REACHED();
}
return value;
}
Optional<DIE::AttributeValue> DIE::get_attribute(const Attribute& attribute) const
{
BufferStream stream(const_cast<ByteBuffer&>(m_compilation_unit.dwarf_info().debug_info_data()));
stream.advance(m_data_offset);
auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
ASSERT(abbreviation_info.has_value());
for (const auto& attribute_spec : abbreviation_info.value().attribute_specifications) {
auto value = get_attribute_value(attribute_spec.form, stream);
if (attribute_spec.attribute == attribute) {
return value;
}
}
return {};
}
void DIE::for_each_child(Function<void(const DIE& child)> callback) const
{
if (!m_has_children)
return;
NonnullOwnPtr<DIE> current_child = make<DIE>(m_compilation_unit, m_offset + m_size);
while (true) {
callback(*current_child);
if (current_child->is_null())
break;
if (!current_child->has_children()) {
current_child = make<DIE>(m_compilation_unit, current_child->offset() + current_child->size());
continue;
}
auto sibling = current_child->get_attribute(Attribute::Sibling);
u32 sibling_offset = 0;
if (sibling.has_value()) {
sibling_offset = sibling.value().data.as_u32;
}
if (!sibling.has_value()) {
// NOTE: According to the spec, the compiler does't have to supply the sibling information.
// When it doesn't, we have to recursively iterate the current child's children to find where they end
current_child->for_each_child([&](const DIE& sub_child) {
sibling_offset = sub_child.offset() + sub_child.size();
});
}
current_child = make<DIE>(m_compilation_unit, sibling_offset);
}
}
DIE DIE::get_die_at_offset(u32 offset) const
{
ASSERT(offset >= m_compilation_unit.offset() && offset < m_compilation_unit.offset() + m_compilation_unit.size());
return DIE(m_compilation_unit, offset);
}
}