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LibDebug: Support addrx*, strx* and rnglistx forms

Browse source 
These forms were introduced in DWARF5, and have a fair deal of
advantages over the more traditional encodings: they reduce the size of
the binary and the number of relocations.

GCC does not emit these with `-g1` by default, but Clang does at all
debug levels.
This commit is contained in:
Daniel Bertalan 2021-10-09 17:38:26 +02:00 committed by Linus Groh
parent 8e5b70a0ba
commit ac53569bd1
7 changed files with 213 additions and 3 deletions
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1
Userland/Libraries/LibDebug/CMakeLists.txt
View file

@ -3,6 +3,7 @@ set(SOURCES
DebugSession.cpp
Dwarf/AbbreviationsMap.cpp
Dwarf/AddressRanges.cpp
Dwarf/AttributeValue.cpp
Dwarf/CompilationUnit.cpp
Dwarf/DIE.cpp
Dwarf/DwarfInfo.cpp

49
Userland/Libraries/LibDebug/Dwarf/AttributeValue.cpp Normal file
View file

@ -0,0 +1,49 @@
/*
* Copyright (c) 2021, Daniel Bertalan <dani@danielbertalan.dev>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "AttributeValue.h"
#include "CompilationUnit.h"
namespace Debug::Dwarf {
FlatPtr AttributeValue::as_addr() const
{
switch (m_form) {
case AttributeDataForm::Addr:
return m_data.as_addr;
case AttributeDataForm::AddrX:
case AttributeDataForm::AddrX1:
case AttributeDataForm::AddrX2:
case AttributeDataForm::AddrX3:
case AttributeDataForm::AddrX4: {
auto index = m_data.as_unsigned;
return m_compilation_unit->get_address(index);
}
default:
VERIFY_NOT_REACHED();
}
}
char const* AttributeValue::as_string() const
{
switch (m_form) {
case AttributeDataForm::String:
case AttributeDataForm::StringPointer:
case AttributeDataForm::LineStrP:
return m_data.as_string;
case AttributeDataForm::StrX:
case AttributeDataForm::StrX1:
case AttributeDataForm::StrX2:
case AttributeDataForm::StrX3:
case AttributeDataForm::StrX4: {
auto index = m_data.as_unsigned;
return m_compilation_unit->get_string(index);
}
default:
VERIFY_NOT_REACHED();
}
}
}

4
Userland/Libraries/LibDebug/Dwarf/AttributeValue.h
View file

@ -33,10 +33,10 @@ public:
Type type() const { return m_type; }
AttributeDataForm form() const { return m_form; }
FlatPtr as_addr() const { return m_data.as_addr; }
FlatPtr as_addr() const;
u64 as_unsigned() const { return m_data.as_unsigned; }
i64 as_signed() const { return m_data.as_signed; }
const char* as_string() const { return m_data.as_string; }
const char* as_string() const;
bool as_bool() const { return m_data.as_bool; }
ReadonlyBytes as_raw_bytes() const { return m_data.as_raw_bytes; }

66
Userland/Libraries/LibDebug/Dwarf/CompilationUnit.cpp
View file

@ -44,4 +44,70 @@ Optional<FlatPtr> CompilationUnit::base_address() const
return m_cached_base_address;
}
u64 CompilationUnit::address_table_base() const
{
if (m_has_cached_address_table_base)
return m_cached_address_table_base;
auto die = root_die();
auto res = die.get_attribute(Attribute::AddrBase);
if (res.has_value()) {
VERIFY(res->form() == AttributeDataForm::SecOffset);
m_cached_address_table_base = res->as_unsigned();
}
m_has_cached_address_table_base = true;
return m_cached_address_table_base;
}
u64 CompilationUnit::string_offsets_base() const
{
if (m_has_cached_string_offsets_base)
return m_cached_string_offsets_base;
auto die = root_die();
auto res = die.get_attribute(Attribute::StrOffsetsBase);
if (res.has_value()) {
VERIFY(res->form() == AttributeDataForm::SecOffset);
m_cached_string_offsets_base = res->as_unsigned();
}
m_has_cached_string_offsets_base = true;
return m_cached_string_offsets_base;
}
u64 CompilationUnit::range_lists_base() const
{
if (m_has_cached_range_lists_base)
return m_cached_range_lists_base;
auto die = root_die();
auto res = die.get_attribute(Attribute::RngListsBase);
if (res.has_value()) {
VERIFY(res->form() == AttributeDataForm::SecOffset);
m_cached_range_lists_base = res->as_unsigned();
}
m_has_cached_range_lists_base = true;
return m_cached_range_lists_base;
}
FlatPtr CompilationUnit::get_address(size_t index) const
{
auto base = address_table_base();
auto debug_addr_data = dwarf_info().debug_addr_data();
VERIFY(base < debug_addr_data.size());
auto addresses = reinterpret_cast<FlatPtr const*>(debug_addr_data.offset(base));
VERIFY(base + index * sizeof(FlatPtr) < debug_addr_data.size());
return addresses[index];
}
char const* CompilationUnit::get_string(size_t index) const
{
auto base = string_offsets_base();
auto debug_str_offsets_data = dwarf_info().debug_str_offsets_data();
VERIFY(base < debug_str_offsets_data.size());
// FIXME: This assumes DWARF32
auto offsets = reinterpret_cast<u32 const*>(debug_str_offsets_data.offset(base));
VERIFY(base + index * sizeof(u32) < debug_str_offsets_data.size());
auto offset = offsets[index];
return reinterpret_cast<char const*>(dwarf_info().debug_strings_data().offset(offset));
}
}

18
Userland/Libraries/LibDebug/Dwarf/CompilationUnit.h
View file

@ -31,19 +31,35 @@ public:
DIE root_die() const;
DIE get_die_at_offset(u32 offset) const;
FlatPtr get_address(size_t index) const;
char const* get_string(size_t index) const;
DwarfInfo const& dwarf_info() const { return m_dwarf_info; }
AbbreviationsMap const& abbreviations_map() const { return m_abbreviations; }
LineProgram const& line_program() const { return *m_line_program; }
Optional<FlatPtr> base_address() const;
// DW_AT_addr_base
u64 address_table_base() const;
// DW_AT_str_offsets_base
u64 string_offsets_base() const;
// DW_AT_rnglists_base
u64 range_lists_base() const;
private:
DwarfInfo const& m_dwarf_info;
u32 m_offset { 0 };
CompilationUnitHeader m_header;
AbbreviationsMap m_abbreviations;
NonnullOwnPtr<LineProgram> m_line_program;
mutable bool m_has_cached_base_address { false };
mutable bool m_has_cached_base_address : 1 { false };
mutable bool m_has_cached_address_table_base : 1 { false };
mutable bool m_has_cached_string_offsets_base : 1 { false };
mutable bool m_has_cached_range_lists_base : 1 { false };
mutable Optional<FlatPtr> m_cached_base_address;
mutable u64 m_cached_address_table_base { 0 };
mutable u64 m_cached_string_offsets_base { 0 };
mutable u64 m_cached_range_lists_base { 0 };
};
}

74
Userland/Libraries/LibDebug/Dwarf/DwarfInfo.cpp
View file

@ -23,6 +23,8 @@ DwarfInfo::DwarfInfo(ELF::Image const& elf)
m_debug_line_data = section_data(".debug_line"sv);
m_debug_line_strings_data = section_data(".debug_line_str"sv);
m_debug_range_lists_data = section_data(".debug_rnglists"sv);
m_debug_str_offsets_data = section_data(".debug_str_offsets"sv);
m_debug_addr_data = section_data(".debug_addr"sv);
populate_compilation_units();
}
@ -230,6 +232,78 @@ AttributeValue DwarfInfo::get_attribute_value(AttributeDataForm form, ssize_t im
value.m_data.as_signed = implicit_const_value;
break;
}
case AttributeDataForm::StrX1: {
u8 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::String;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::StrX2: {
u16 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::String;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::StrX4: {
u32 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::String;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::StrX: {
size_t index;
debug_info_stream.read_LEB128_unsigned(index);
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::String;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::AddrX1: {
u8 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::Address;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::AddrX2: {
u16 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::Address;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::AddrX4: {
u32 index;
debug_info_stream >> index;
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::Address;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::AddrX: {
size_t index;
debug_info_stream.read_LEB128_unsigned(index);
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::Address;
value.m_data.as_unsigned = index;
break;
}
case AttributeDataForm::RngListX: {
size_t index;
debug_info_stream.read_LEB128_unsigned(index);
VERIFY(!debug_info_stream.has_any_error());
value.m_type = AttributeValue::Type::UnsignedNumber;
value.m_data.as_unsigned = index;
break;
}
default:
dbgln("Unimplemented AttributeDataForm: {}", (u32)form);
VERIFY_NOT_REACHED();

4
Userland/Libraries/LibDebug/Dwarf/DwarfInfo.h
View file

@ -31,6 +31,8 @@ public:
ReadonlyBytes debug_strings_data() const { return m_debug_strings_data; }
ReadonlyBytes debug_line_strings_data() const { return m_debug_line_strings_data; }
ReadonlyBytes debug_range_lists_data() const { return m_debug_range_lists_data; }
ReadonlyBytes debug_str_offsets_data() const { return m_debug_str_offsets_data; }
ReadonlyBytes debug_addr_data() const { return m_debug_addr_data; }
template<typename Callback>
void for_each_compilation_unit(Callback) const;
@ -60,6 +62,8 @@ private:
ReadonlyBytes m_debug_line_data;
ReadonlyBytes m_debug_line_strings_data;
ReadonlyBytes m_debug_range_lists_data;
ReadonlyBytes m_debug_str_offsets_data;
ReadonlyBytes m_debug_addr_data;
NonnullOwnPtrVector<Dwarf::CompilationUnit> m_compilation_units;