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https://github.com/RGBCube/serenity
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LibDebug: Support shared libraries
DebugSession now makes the loader stop after loading the libraries, and parses the loaded libraries of the program before continuing its execution. DebugSession now also supports inserting a breakpoint at a given symbol or source position. Additionally, DebugInfo now takes the base address of its object into consideration.
This commit is contained in:
Itamar
Andreas Kling
parent
ca9d6d21b5
commit
4b91e7c821
6 changed files with 328 additions and 53 deletions
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@ -25,15 +25,20 @@
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*/
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#include "DebugSession.h"
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#include <AK/JsonObject.h>
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#include <AK/JsonValue.h>
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#include <AK/LexicalPath.h>
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#include <AK/Optional.h>
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#include <LibCore/File.h>
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#include <LibRegex/Regex.h>
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#include <stdlib.h>
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namespace Debug {
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DebugSession::DebugSession(pid_t pid)
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DebugSession::DebugSession(pid_t pid, String source_root)
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: m_debuggee_pid(pid)
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, m_executable(map_executable_for_process(pid))
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, m_debug_info(make<ELF::Image>(reinterpret_cast<const u8*>(m_executable.data()), m_executable.size()))
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, m_source_root(source_root)
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{
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}
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@ -59,7 +64,7 @@ DebugSession::~DebugSession()
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}
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}
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OwnPtr<DebugSession> DebugSession::exec_and_attach(const String& command)
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OwnPtr<DebugSession> DebugSession::exec_and_attach(const String& command, String source_root)
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{
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auto pid = fork();
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@ -80,7 +85,10 @@ OwnPtr<DebugSession> DebugSession::exec_and_attach(const String& command)
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for (size_t i = 0; i < parts.size(); i++) {
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args[i] = parts[i].characters();
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}
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int rc = execvp(args[0], const_cast<char**>(args));
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const char** envp = (const char**)calloc(2, sizeof(const char*));
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// This causes loader to stop on a breakpoint before jumping to the entry point of the program.
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envp[0] = "_LOADER_BREAKPOINT=1";
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int rc = execvpe(args[0], const_cast<char**>(args), const_cast<char**>(envp));
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if (rc < 0) {
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perror("execvp");
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}
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@ -107,7 +115,19 @@ OwnPtr<DebugSession> DebugSession::exec_and_attach(const String& command)
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return nullptr;
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}
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return adopt_own(*new DebugSession(pid));
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auto debug_session = adopt_own(*new DebugSession(pid, source_root));
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// Continue until breakpoint before entry point of main program
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int wstatus = debug_session->continue_debuggee_and_wait();
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if (WSTOPSIG(wstatus) != SIGTRAP) {
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dbgln("expected SIGTRAP");
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return nullptr;
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}
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// At this point, libraries should have been loaded
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debug_session->update_loaded_libs();
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return move(debug_session);
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}
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bool DebugSession::poke(u32* address, u32 data)
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@ -268,4 +288,152 @@ void DebugSession::detach()
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continue_debuggee();
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}
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Optional<DebugSession::InsertBreakpointAtSymbolResult> DebugSession::insert_breakpoint(const String& symbol_name)
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{
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Optional<InsertBreakpointAtSymbolResult> result;
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for_each_loaded_library([this, symbol_name, &result](auto& lib) {
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// The loader contains its own definitions for LibC symbols, so we don't want to include it in the search.
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if (lib.name == "Loader.so")
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return IterationDecision::Continue;
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auto symbol = lib.debug_info->elf().find_demangled_function(symbol_name);
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if (!symbol.has_value())
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return IterationDecision::Continue;
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auto breakpoint_address = symbol.value().value() + lib.base_address;
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bool rc = this->insert_breakpoint(reinterpret_cast<void*>(breakpoint_address));
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if (!rc)
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return IterationDecision::Break;
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result = InsertBreakpointAtSymbolResult { lib.name, breakpoint_address };
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return IterationDecision::Break;
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});
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return result;
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}
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Optional<DebugSession::InsertBreakpointAtSourcePositionResult> DebugSession::insert_breakpoint(const String& file_name, size_t line_number)
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{
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auto address_and_source_position = get_address_from_source_position(file_name, line_number);
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if (!address_and_source_position.has_value())
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return {};
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auto address = address_and_source_position.value().address;
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bool rc = this->insert_breakpoint(reinterpret_cast<void*>(address));
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if (!rc)
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return {};
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auto lib = library_at(address);
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ASSERT(lib);
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return InsertBreakpointAtSourcePositionResult { lib->name, address_and_source_position.value().file, address_and_source_position.value().line, address };
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}
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void DebugSession::update_loaded_libs()
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{
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auto file = Core::File::construct(String::format("/proc/%u/vm", m_debuggee_pid));
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bool rc = file->open(Core::IODevice::ReadOnly);
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ASSERT(rc);
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auto file_contents = file->read_all();
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auto json = JsonValue::from_string(file_contents);
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ASSERT(json.has_value());
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auto vm_entries = json.value().as_array();
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Regex<PosixExtended> re("(.+): \\.text");
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auto get_path_to_object = [&re](const String& vm_name) -> Optional<String> {
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if (vm_name == "/usr/lib/Loader.so")
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return vm_name;
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RegexResult result;
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auto rc = re.search(vm_name, result);
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if (!rc)
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return {};
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auto lib_name = result.capture_group_matches.at(0).at(0).view.u8view().to_string();
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if (lib_name.starts_with("/"))
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return lib_name;
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return String::format("/usr/lib/%s", lib_name.characters());
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};
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vm_entries.for_each([&](auto& entry) {
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// TODO: check that region is executable
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auto vm_name = entry.as_object().get("name").as_string();
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auto object_path = get_path_to_object(vm_name);
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if (!object_path.has_value())
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return IterationDecision::Continue;
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String lib_name = object_path.value();
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if (lib_name.ends_with(".so"))
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lib_name = LexicalPath(object_path.value()).basename();
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// FIXME: DebugInfo currently cannot parse the debug information of libgcc_s.so
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if (lib_name == "libgcc_s.so")
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return IterationDecision::Continue;
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if (m_loaded_libraries.contains(lib_name))
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return IterationDecision::Continue;
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MappedFile lib_file(object_path.value());
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if (!lib_file.is_valid())
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return IterationDecision::Continue;
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FlatPtr base_address = entry.as_object().get("address").as_u32();
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auto debug_info = make<DebugInfo>(make<ELF::Image>(reinterpret_cast<const u8*>(lib_file.data()), lib_file.size()), m_source_root, base_address);
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auto lib = make<LoadedLibrary>(lib_name, move(lib_file), move(debug_info), base_address);
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m_loaded_libraries.set(lib_name, move(lib));
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return IterationDecision::Continue;
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});
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}
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const DebugSession::LoadedLibrary* DebugSession::library_at(FlatPtr address) const
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{
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const LoadedLibrary* result = nullptr;
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for_each_loaded_library([&result, address](const auto& lib) {
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if (address >= lib.base_address && address < lib.base_address + lib.debug_info->elf().size()) {
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result = &lib;
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return IterationDecision::Break;
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}
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return IterationDecision::Continue;
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});
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return result;
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}
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Optional<DebugSession::SymbolicationResult> DebugSession::symbolicate(FlatPtr address) const
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{
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auto* lib = library_at(address);
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if (!lib)
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return {};
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//FIXME: ELF::Image symlicate() API should return String::empty() if symbol is not found (It currently returns ??)
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auto symbol = lib->debug_info->elf().symbolicate(address - lib->base_address);
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return { { lib->name, symbol } };
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}
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Optional<DebugInfo::SourcePositionAndAddress> DebugSession::get_address_from_source_position(const String& file, size_t line) const
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{
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Optional<DebugInfo::SourcePositionAndAddress> result;
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for_each_loaded_library([this, file, line, &result](auto& lib) {
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// The loader contains its own definitions for LibC symbols, so we don't want to include it in the search.
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if (lib.name == "Loader.so")
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return IterationDecision::Continue;
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auto source_position_and_address = lib.debug_info->get_address_from_source_position(file, line);
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if (!source_position_and_address.has_value())
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return IterationDecision::Continue;
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result = source_position_and_address;
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result.value().address += lib.base_address;
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return IterationDecision::Break;
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});
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return result;
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}
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Optional<DebugInfo::SourcePosition> DebugSession::get_source_position(FlatPtr address) const
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{
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auto* lib = library_at(address);
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if (!lib)
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return {};
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return lib->debug_info->get_source_position(address - lib->base_address);
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}
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}
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