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UserspaceEmulator: Make symbolication work when .text isn't the first

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... segment

This happens with binaries build with Clang or with a custom linker
script. If this is the case, offsets should be calculated not from the
base address of `.text`, but from the first section loaded for the
library.

This commit moves all UserspaceEmulator symbolication into a common
helper function and fixes a FIXME.
This commit is contained in:
Daniel Bertalan 2021-07-28 17:18:43 +02:00 • committed by Andreas Kling
parent 980f314a03
commit c1d6637dc7
4 changed files with 77 additions and 55 deletions
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103
Userland/DevTools/UserspaceEmulator/Emulator.cpp
View file

@ -276,19 +276,10 @@ void Emulator::handle_repl()
auto saved_eip = m_cpu.eip(); auto saved_eip = m_cpu.eip();
m_cpu.save_base_eip(); m_cpu.save_base_eip();
auto insn = X86::Instruction::from_stream(m_cpu, true, true); auto insn = X86::Instruction::from_stream(m_cpu, true, true);
// FIXME: This does not respect inlineing // FIXME: This does not respect inlining
// another way of getting the current function is at need // another way of getting the current function is at need
if (auto const* region = load_library_from_address(m_cpu.base_eip())) { if (auto symbol = symbol_at(m_cpu.base_eip()); symbol.has_value()) {
auto separator_index = region->name().find(":").value(); outln("[{}]: {}", symbol->lib_name, symbol->symbol);
String lib_name = region->name().substring(0, separator_index);
String lib_path = lib_name;
if (region->name().contains(".so"))
lib_path = String::formatted("/usr/lib/{}", lib_path);
auto it = m_dynamic_library_cache.find(lib_path);
auto& elf = it->value.debug_info->elf();
String symbol = elf.symbolicate(m_cpu.base_eip() - region->base());
outln("[{}]: {}", lib_name, symbol);
} }
outln("==> {}", create_instruction_line(m_cpu.base_eip(), insn)); outln("==> {}", create_instruction_line(m_cpu.base_eip(), insn));
@ -405,11 +396,11 @@ MmapRegion const* Emulator::load_library_from_address(FlatPtr address)
auto const* region = find_text_region(address); auto const* region = find_text_region(address);
if (!region) if (!region)
return {}; return {};
auto separator_index = region->name().find(':');
if (!separator_index.has_value()) String lib_name = region->lib_name();
if (lib_name.is_null())
return {}; return {};
String lib_name = region->name().substring(0, separator_index.value());
String lib_path = lib_name; String lib_path = lib_name;
if (region->name().contains(".so")) if (region->name().contains(".so"))
lib_path = String::formatted("/usr/lib/{}", lib_path); lib_path = String::formatted("/usr/lib/{}", lib_path);
@ -426,30 +417,49 @@ MmapRegion const* Emulator::load_library_from_address(FlatPtr address)
return region; return region;
} }
String Emulator::create_backtrace_line(FlatPtr address) MmapRegion const* Emulator::first_region_for_object(StringView name)
{ {
auto minimal = String::formatted("=={{{}}}== {:p}", getpid(), (void*)address); MmapRegion* ret = nullptr;
auto const* region = load_library_from_address(address); mmu().for_each_region_of_type<MmapRegion>([&](auto& region) {
if (!region) if (region.lib_name() == name) {
return minimal; ret = &region;
// FIXME: This is redundant return IterationDecision::Break;
auto separator_index = region->name().find(":").value(); }
String lib_name = region->name().substring(0, separator_index); return IterationDecision::Continue;
String lib_path = lib_name; });
if (region->name().contains(".so")) return ret;
lib_path = String::formatted("/usr/lib/{}", lib_path); }
// FIXME: This disregards function inlining.
Optional<Emulator::SymbolInfo> Emulator::symbol_at(FlatPtr address)
{
auto const* address_region = load_library_from_address(address);
if (!address_region)
return {};
auto lib_name = address_region->lib_name();
auto const* first_region = (lib_name.is_null() || lib_name.is_empty()) ? address_region : first_region_for_object(lib_name);
VERIFY(first_region);
auto lib_path = lib_name.contains(".so"sv) ? String::formatted("/usr/lib/{}", lib_name) : lib_name;
auto it = m_dynamic_library_cache.find(lib_path); auto it = m_dynamic_library_cache.find(lib_path);
auto& elf = it->value.debug_info->elf(); auto const& elf = it->value.debug_info->elf();
String symbol = elf.symbolicate(address - region->base()); auto symbol = elf.symbolicate(address - first_region->base());
auto line_without_source_info = String::formatted("=={{{}}}== {:p} [{}]: {}", getpid(), (void*)address, lib_name, symbol); auto source_position = it->value.debug_info->get_source_position(address - first_region->base());
return { { lib_name, symbol, source_position } };
}
auto source_position = it->value.debug_info->get_source_position(address - region->base()); String Emulator::create_backtrace_line(FlatPtr address)
if (source_position.has_value()) {
return String::formatted("=={{{}}}== {:p} [{}]: {} (\e[34;1m{}\e[0m:{})", getpid(), (void*)address, lib_name, symbol, LexicalPath::basename(source_position.value().file_path), source_position.value().line_number); auto maybe_symbol = symbol_at(address);
if (!maybe_symbol.has_value()) {
return line_without_source_info; return String::formatted("=={{{}}}== {:p}", getpid(), address);
} else if (!maybe_symbol->source_position.has_value()) {
return String::formatted("=={{{}}}== {:p} [{}]: {}", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol);
} else {
auto const& source_position = maybe_symbol->source_position.value();
return String::formatted("=={{{}}}== {:p} [{}]: {} (\e[34;1m{}\e[0m:{})", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol, LexicalPath::basename(source_position.file_path), source_position.line_number);
}
} }
void Emulator::dump_backtrace(Vector<FlatPtr> const& backtrace) void Emulator::dump_backtrace(Vector<FlatPtr> const& backtrace)
@ -486,26 +496,11 @@ void Emulator::emit_profile_event(AK::OutputStream& output, StringView event_nam
String Emulator::create_instruction_line(FlatPtr address, X86::Instruction insn) String Emulator::create_instruction_line(FlatPtr address, X86::Instruction insn)
{ {
auto minimal = String::formatted("{:p}: {}", (void*)address, insn.to_string(address)); auto symbol = symbol_at(address);
auto const* region = load_library_from_address(address); if (!symbol.has_value() || !symbol->source_position.has_value())
if (!region) return String::formatted("{:p}: {}", address, insn.to_string(address));
return minimal; else
// FIXME: This is redundant return String::formatted("{:p}: {} \e[34;1m{}\e[0m:{}", address, insn.to_string(address), LexicalPath::basename(symbol->source_position->file_path), symbol->source_position.value().line_number);
auto separator_index = region->name().find(":").value();
String lib_name = region->name().substring(0, separator_index);
String lib_path = lib_name;
if (region->name().contains(".so"))
lib_path = String::formatted("/usr/lib/{}", lib_path);
auto it = m_dynamic_library_cache.find(lib_path);
auto& elf = it->value.debug_info->elf();
String symbol = elf.symbolicate(address - region->base());
auto source_position = it->value.debug_info->get_source_position(address - region->base());
if (!source_position.has_value())
return minimal;
return String::formatted("{:p}: {} \e[34;1m{}\e[0m:{}", (void*)address, insn.to_string(address), LexicalPath::basename(source_position.value().file_path), source_position.value().line_number);
} }
static void emulator_signal_handler(int signum) static void emulator_signal_handler(int signum)

10
Userland/DevTools/UserspaceEmulator/Emulator.h
View file

@ -79,6 +79,14 @@ public:
pause(); pause();
} }
struct SymbolInfo {
String lib_name;
String symbol;
Optional<Debug::DebugInfo::SourcePosition> source_position;
};
Optional<SymbolInfo> symbol_at(FlatPtr address);
void dump_regions() const; void dump_regions() const;
private: private:
@ -211,7 +219,7 @@ private:
void dispatch_one_pending_signal(); void dispatch_one_pending_signal();
MmapRegion const* find_text_region(FlatPtr address); MmapRegion const* find_text_region(FlatPtr address);
MmapRegion const* load_library_from_address(FlatPtr address); MmapRegion const* load_library_from_address(FlatPtr address);
String symbol_at(FlatPtr address); MmapRegion const* first_region_for_object(StringView name);
String create_backtrace_line(FlatPtr address); String create_backtrace_line(FlatPtr address);
String create_instruction_line(FlatPtr address, X86::Instruction insn); String create_instruction_line(FlatPtr address, X86::Instruction insn);

9
Userland/DevTools/UserspaceEmulator/MmapRegion.h
View file

@ -52,6 +52,15 @@ public:
void set_malloc_metadata(Badge<MallocTracer>, NonnullOwnPtr<MallocRegionMetadata> metadata) { m_malloc_metadata = move(metadata); } void set_malloc_metadata(Badge<MallocTracer>, NonnullOwnPtr<MallocRegionMetadata> metadata) { m_malloc_metadata = move(metadata); }
const String& name() const { return m_name; } const String& name() const { return m_name; }
String lib_name() const
{
if (m_name.contains("Loader.so"sv))
return "Loader.so";
auto const maybe_separator = m_name.find(':');
if (!maybe_separator.has_value())
return {};
return m_name.substring(0, *maybe_separator);
}
void set_name(String name) { m_name = move(name); } void set_name(String name) { m_name = move(name); }
private: private:

10
Userland/DevTools/UserspaceEmulator/SoftMMU.h
View file

@ -71,6 +71,16 @@ public:
} }
} }
template<typename Type, typename Callback>
void for_each_region_of_type(Callback callback)
{
return for_each_region([callback](auto& region) {
if (!is<Type>(region))
return IterationDecision::Continue;
return callback(static_cast<Type&>(region));
});
}
template<typename Callback> template<typename Callback>
void for_regions_in(X86::LogicalAddress address, size_t size, Callback callback) void for_regions_in(X86::LogicalAddress address, size_t size, Callback callback)
{ {