//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++
//-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "AppleObjCTrampolineHandler.h"
#include "AppleThreadPlanStepThroughObjCTrampoline.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/StreamFile.h"
#include "lldb/Core/Value.h"
#include "lldb/Expression/DiagnosticManager.h"
#include "lldb/Expression/FunctionCaller.h"
#include "lldb/Expression/UserExpression.h"
#include "lldb/Expression/UtilityFunction.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/Log.h"
#include "llvm/ADT/STLExtras.h"
#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
#include <memory>
using namespace lldb;
using namespace lldb_private;
const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name =
"__lldb_objc_find_implementation_for_selector";
const char *AppleObjCTrampolineHandler::
g_lookup_implementation_with_stret_function_code =
" \n\
extern \"C\" \n\
{ \n\
extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\
extern void *class_getMethodImplementation_stret(void *objc_class, \n\
void *sel); \n\
extern void * object_getClass (id object); \n\
extern void * sel_getUid(char *name); \n\
extern int printf(const char *format, ...); \n\
} \n\
extern \"C\" void * __lldb_objc_find_implementation_for_selector ( \n\
void *object, \n\
void *sel, \n\
int is_stret, \n\
int is_super, \n\
int is_super2, \n\
int is_fixup, \n\
int is_fixed, \n\
int debug) \n\
{ \n\
struct __lldb_imp_return_struct \n\
{ \n\
void *class_addr; \n\
void *sel_addr; \n\
void *impl_addr; \n\
}; \n\
\n\
struct __lldb_objc_class { \n\
void *isa; \n\
void *super_ptr; \n\
}; \n\
struct __lldb_objc_super { \n\
void *receiver; \n\
struct __lldb_objc_class *class_ptr; \n\
}; \n\
struct __lldb_msg_ref { \n\
void *dont_know; \n\
void *sel; \n\
}; \n\
\n\
struct __lldb_imp_return_struct return_struct; \n\
\n\
if (debug) \n\
printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"\n\
\"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\
object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);\n\
if (is_super) \n\
{ \n\
if (is_super2) \n\
{ \n\
return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;\n\
} \n\
else \n\
{ \n\
return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;\n\
} \n\
} \n\
else \n\
{ \n\
// This code seems a little funny, but has its reasons... \n\
\n\
// The call to [object class] is here because if this is a \n\
// class, and has not been called into yet, we need to do \n\
// something to force the class to initialize itself. \n\
// Then the call to object_getClass will actually return the \n\
// correct class, either the class if object is a class \n\
// instance, or the meta-class if it is a class pointer. \n\
void *class_ptr = (void *) [(id) object class]; \n\
return_struct.class_addr = (id) object_getClass((id) object); \n\
if (debug) \n\
{ \n\
if (class_ptr == object) \n\
{ \n\
printf (\"Found a class object, need to use the meta class %p -> %p\\n\",\n\
class_ptr, return_struct.class_addr); \n\
} \n\
else \n\
{ \n\
printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\
class_ptr, return_struct.class_addr); \n\
} \n\
} \n\
} \n\
\n\
if (is_fixup) \n\
{ \n\
if (is_fixed) \n\
{ \n\
return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\
} \n\
else \n\
{ \n\
char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\
return_struct.sel_addr = sel_getUid (sel_name); \n\
if (debug) \n\
printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\
return_struct.sel_addr, sel_name); \n\
} \n\
} \n\
else \n\
{ \n\
return_struct.sel_addr = sel; \n\
} \n\
\n\
if (is_stret) \n\
{ \n\
return_struct.impl_addr = \n\
class_getMethodImplementation_stret (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
} \n\
else \n\
{ \n\
return_struct.impl_addr = \n\
class_getMethodImplementation (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
} \n\
if (debug) \n\
printf (\"\\n*** Returning implementation: %p.\\n\", \n\
return_struct.impl_addr); \n\
\n\
return return_struct.impl_addr; \n\
} \n\
";
const char *
AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code =
" \n\
extern \"C\" \n\
{ \n\
extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\
extern void * object_getClass (id object); \n\
extern void * sel_getUid(char *name); \n\
extern int printf(const char *format, ...); \n\
} \n\
extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object, \n\
void *sel, \n\
int is_stret, \n\
int is_super, \n\
int is_super2, \n\
int is_fixup, \n\
int is_fixed, \n\
int debug) \n\
{ \n\
struct __lldb_imp_return_struct \n\
{ \n\
void *class_addr; \n\
void *sel_addr; \n\
void *impl_addr; \n\
}; \n\
\n\
struct __lldb_objc_class { \n\
void *isa; \n\
void *super_ptr; \n\
}; \n\
struct __lldb_objc_super { \n\
void *receiver; \n\
struct __lldb_objc_class *class_ptr; \n\
}; \n\
struct __lldb_msg_ref { \n\
void *dont_know; \n\
void *sel; \n\
}; \n\
\n\
struct __lldb_imp_return_struct return_struct; \n\
\n\
if (debug) \n\
printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \" \n\
\"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\", \n\
object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed); \n\
if (is_super) \n\
{ \n\
if (is_super2) \n\
{ \n\
return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr; \n\
} \n\
else \n\
{ \n\
return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr; \n\
} \n\
} \n\
else \n\
{ \n\
// This code seems a little funny, but has its reasons... \n\
// The call to [object class] is here because if this is a class, and has not been called into \n\
// yet, we need to do something to force the class to initialize itself. \n\
// Then the call to object_getClass will actually return the correct class, either the class \n\
// if object is a class instance, or the meta-class if it is a class pointer. \n\
void *class_ptr = (void *) [(id) object class]; \n\
return_struct.class_addr = (id) object_getClass((id) object); \n\
if (debug) \n\
{ \n\
if (class_ptr == object) \n\
{ \n\
printf (\"Found a class object, need to return the meta class %p -> %p\\n\", \n\
class_ptr, return_struct.class_addr); \n\
} \n\
else \n\
{ \n\
printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\
class_ptr, return_struct.class_addr); \n\
} \n\
} \n\
} \n\
\n\
if (is_fixup) \n\
{ \n\
if (is_fixed) \n\
{ \n\
return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel; \n\
} \n\
else \n\
{ \n\
char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel; \n\
return_struct.sel_addr = sel_getUid (sel_name); \n\
if (debug) \n\
printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\
return_struct.sel_addr, sel_name); \n\
} \n\
} \n\
else \n\
{ \n\
return_struct.sel_addr = sel; \n\
} \n\
\n\
return_struct.impl_addr = \n\
class_getMethodImplementation (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
if (debug) \n\
printf (\"\\n*** Returning implementation: 0x%p.\\n\", \n\
return_struct.impl_addr); \n\
\n\
return return_struct.impl_addr; \n\
} \n\
";
AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(
AppleObjCVTables *owner, lldb::addr_t header_addr)
: m_valid(true), m_owner(owner), m_header_addr(header_addr),
m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) {
SetUpRegion();
}
AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {}
void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() {
// The header looks like:
//
// uint16_t headerSize
// uint16_t descSize
// uint32_t descCount
// void * next
//
// First read in the header:
char memory_buffer[16];
ProcessSP process_sp = m_owner->GetProcessSP();
if (!process_sp)
return;
DataExtractor data(memory_buffer, sizeof(memory_buffer),
process_sp->GetByteOrder(),
process_sp->GetAddressByteSize());
size_t actual_size = 8 + process_sp->GetAddressByteSize();
Status error;
size_t bytes_read =
process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error);
if (bytes_read != actual_size) {
m_valid = false;
return;
}
lldb::offset_t offset = 0;
const uint16_t header_size = data.GetU16(&offset);
const uint16_t descriptor_size = data.GetU16(&offset);
const size_t num_descriptors = data.GetU32(&offset);
m_next_region = data.GetPointer(&offset);
// If the header size is 0, that means we've come in too early before this
// data is set up.
// Set ourselves as not valid, and continue.
if (header_size == 0 || num_descriptors == 0) {
m_valid = false;
return;
}
// Now read in all the descriptors:
// The descriptor looks like:
//
// uint32_t offset
// uint32_t flags
//
// Where offset is either 0 - in which case it is unused, or it is
// the offset of the vtable code from the beginning of the
// descriptor record. Below, we'll convert that into an absolute
// code address, since I don't want to have to compute it over and
// over.
// Ingest the whole descriptor array:
const lldb::addr_t desc_ptr = m_header_addr + header_size;
const size_t desc_array_size = num_descriptors * descriptor_size;
DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0'));
uint8_t *dst = (uint8_t *)data_sp->GetBytes();
DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(),
process_sp->GetAddressByteSize());
bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error);
if (bytes_read != desc_array_size) {
m_valid = false;
return;
}
// The actual code for the vtables will be laid out consecutively, so I also
// compute the start and end of the whole code block.
offset = 0;
m_code_start_addr = 0;
m_code_end_addr = 0;
for (size_t i = 0; i < num_descriptors; i++) {
lldb::addr_t start_offset = offset;
uint32_t voffset = desc_extractor.GetU32(&offset);
uint32_t flags = desc_extractor.GetU32(&offset);
lldb::addr_t code_addr = desc_ptr + start_offset + voffset;
m_descriptors.push_back(VTableDescriptor(flags, code_addr));
if (m_code_start_addr == 0 || code_addr < m_code_start_addr)
m_code_start_addr = code_addr;
if (code_addr > m_code_end_addr)
m_code_end_addr = code_addr;
offset = start_offset + descriptor_size;
}
// Finally, a little bird told me that all the vtable code blocks
// are the same size. Let's compute the blocks and if they are all
// the same add the size to the code end address:
lldb::addr_t code_size = 0;
bool all_the_same = true;
for (size_t i = 0; i < num_descriptors - 1; i++) {
lldb::addr_t this_size =
m_descriptors[i + 1].code_start - m_descriptors[i].code_start;
if (code_size == 0)
code_size = this_size;
else {
if (this_size != code_size)
all_the_same = false;
if (this_size > code_size)
code_size = this_size;
}
}
if (all_the_same)
m_code_end_addr += code_size;
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::
AddressInRegion(lldb::addr_t addr, uint32_t &flags) {
if (!IsValid())
return false;
if (addr < m_code_start_addr || addr > m_code_end_addr)
return false;
std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end();
for (pos = m_descriptors.begin(); pos != end; pos++) {
if (addr <= (*pos).code_start) {
flags = (*pos).flags;
return true;
}
}
return false;
}
void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump(
Stream &s) {
s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64
" Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n",
m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region);
size_t num_elements = m_descriptors.size();
for (size_t i = 0; i < num_elements; i++) {
s.Indent();
s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n",
m_descriptors[i].code_start, m_descriptors[i].flags);
}
}
AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables(
const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
: m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS),
m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID),
m_objc_module_sp(objc_module_sp) {
if (process_sp)
m_process_wp = process_sp;
}
AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() {
ProcessSP process_sp = GetProcessSP();
if (process_sp) {
if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID)
process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id);
}
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() {
if (m_trampoline_header != LLDB_INVALID_ADDRESS)
return true;
ProcessSP process_sp = GetProcessSP();
if (process_sp) {
Target &target = process_sp->GetTarget();
const ModuleList &target_modules = target.GetImages();
std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex());
size_t num_modules = target_modules.GetSize();
if (!m_objc_module_sp) {
for (size_t i = 0; i < num_modules; i++) {
if (ObjCLanguageRuntime::Get(*process_sp)
->IsModuleObjCLibrary(
target_modules.GetModuleAtIndexUnlocked(i))) {
m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i);
break;
}
}
}
if (m_objc_module_sp) {
ConstString trampoline_name("gdb_objc_trampolines");
const Symbol *trampoline_symbol =
m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name,
eSymbolTypeData);
if (trampoline_symbol != nullptr) {
m_trampoline_header = trampoline_symbol->GetLoadAddress(&target);
if (m_trampoline_header == LLDB_INVALID_ADDRESS)
return false;
// Next look up the "changed" symbol and set a breakpoint on that...
ConstString changed_name("gdb_objc_trampolines_changed");
const Symbol *changed_symbol =
m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name,
eSymbolTypeCode);
if (changed_symbol != nullptr) {
const Address changed_symbol_addr = changed_symbol->GetAddress();
if (!changed_symbol_addr.IsValid())
return false;
lldb::addr_t changed_addr =
changed_symbol_addr.GetOpcodeLoadAddress(&target);
if (changed_addr != LLDB_INVALID_ADDRESS) {
BreakpointSP trampolines_changed_bp_sp =
target.CreateBreakpoint(changed_addr, true, false);
if (trampolines_changed_bp_sp) {
m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID();
trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this,
true);
trampolines_changed_bp_sp->SetBreakpointKind(
"objc-trampolines-changed");
return true;
}
}
}
}
}
}
return false;
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines(
void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id,
lldb::user_id_t break_loc_id) {
AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton;
if (vtable_handler->InitializeVTableSymbols()) {
// The Update function is called with the address of an added region. So we
// grab that address, and
// feed it into ReadRegions. Of course, our friend the ABI will get the
// values for us.
ExecutionContext exe_ctx(context->exe_ctx_ref);
Process *process = exe_ctx.GetProcessPtr();
const ABI *abi = process->GetABI().get();
ClangASTContext *clang_ast_context =
ClangASTContext::GetScratch(process->GetTarget());
if (!clang_ast_context)
return false;
ValueList argument_values;
Value input_value;
CompilerType clang_void_ptr_type =
clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
input_value.SetValueType(Value::eValueTypeScalar);
// input_value.SetContext (Value::eContextTypeClangType,
// clang_void_ptr_type);
input_value.SetCompilerType(clang_void_ptr_type);
argument_values.PushValue(input_value);
bool success =
abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values);
if (!success)
return false;
// Now get a pointer value from the zeroth argument.
Status error;
DataExtractor data;
error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data,
nullptr);
lldb::offset_t offset = 0;
lldb::addr_t region_addr = data.GetPointer(&offset);
if (region_addr != 0)
vtable_handler->ReadRegions(region_addr);
}
return false;
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() {
// The no argument version reads the start region from the value of
// the gdb_regions_header, and gets started from there.
m_regions.clear();
if (!InitializeVTableSymbols())
return false;
Status error;
ProcessSP process_sp = GetProcessSP();
if (process_sp) {
lldb::addr_t region_addr =
process_sp->ReadPointerFromMemory(m_trampoline_header, error);
if (error.Success())
return ReadRegions(region_addr);
}
return false;
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions(
lldb::addr_t region_addr) {
ProcessSP process_sp = GetProcessSP();
if (!process_sp)
return false;
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
// We aren't starting at the trampoline symbol.
InitializeVTableSymbols();
lldb::addr_t next_region = region_addr;
// Read in the sizes of the headers.
while (next_region != 0) {
m_regions.push_back(VTableRegion(this, next_region));
if (!m_regions.back().IsValid()) {
m_regions.clear();
return false;
}
if (log) {
StreamString s;
m_regions.back().Dump(s);
LLDB_LOGF(log, "Read vtable region: \n%s", s.GetData());
}
next_region = m_regions.back().GetNextRegionAddr();
}
return true;
}
bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables(
lldb::addr_t addr, uint32_t &flags) {
region_collection::iterator pos, end = m_regions.end();
for (pos = m_regions.begin(); pos != end; pos++) {
if ((*pos).AddressInRegion(addr, flags))
return true;
}
return false;
}
const AppleObjCTrampolineHandler::DispatchFunction
AppleObjCTrampolineHandler::g_dispatch_functions[] = {
// NAME STRET SUPER SUPER2 FIXUP TYPE
{"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone},
{"objc_msgSend_fixup", false, false, false,
DispatchFunction::eFixUpToFix},
{"objc_msgSend_fixedup", false, false, false,
DispatchFunction::eFixUpFixed},
{"objc_msgSend_stret", true, false, false,
DispatchFunction::eFixUpNone},
{"objc_msgSend_stret_fixup", true, false, false,
DispatchFunction::eFixUpToFix},
{"objc_msgSend_stret_fixedup", true, false, false,
DispatchFunction::eFixUpFixed},
{"objc_msgSend_fpret", false, false, false,
DispatchFunction::eFixUpNone},
{"objc_msgSend_fpret_fixup", false, false, false,
DispatchFunction::eFixUpToFix},
{"objc_msgSend_fpret_fixedup", false, false, false,
DispatchFunction::eFixUpFixed},
{"objc_msgSend_fp2ret", false, false, true,
DispatchFunction::eFixUpNone},
{"objc_msgSend_fp2ret_fixup", false, false, true,
DispatchFunction::eFixUpToFix},
{"objc_msgSend_fp2ret_fixedup", false, false, true,
DispatchFunction::eFixUpFixed},
{"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone},
{"objc_msgSendSuper_stret", true, true, false,
DispatchFunction::eFixUpNone},
{"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone},
{"objc_msgSendSuper2_fixup", false, true, true,
DispatchFunction::eFixUpToFix},
{"objc_msgSendSuper2_fixedup", false, true, true,
DispatchFunction::eFixUpFixed},
{"objc_msgSendSuper2_stret", true, true, true,
DispatchFunction::eFixUpNone},
{"objc_msgSendSuper2_stret_fixup", true, true, true,
DispatchFunction::eFixUpToFix},
{"objc_msgSendSuper2_stret_fixedup", true, true, true,
DispatchFunction::eFixUpFixed},
};
AppleObjCTrampolineHandler::AppleObjCTrampolineHandler(
const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
: m_process_wp(), m_objc_module_sp(objc_module_sp),
m_lookup_implementation_function_code(nullptr),
m_impl_fn_addr(LLDB_INVALID_ADDRESS),
m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS),
m_msg_forward_addr(LLDB_INVALID_ADDRESS) {
if (process_sp)
m_process_wp = process_sp;
// Look up the known resolution functions:
ConstString get_impl_name("class_getMethodImplementation");
ConstString get_impl_stret_name("class_getMethodImplementation_stret");
ConstString msg_forward_name("_objc_msgForward");
ConstString msg_forward_stret_name("_objc_msgForward_stret");
Target *target = process_sp ? &process_sp->GetTarget() : nullptr;
const Symbol *class_getMethodImplementation =
m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_name,
eSymbolTypeCode);
const Symbol *class_getMethodImplementation_stret =
m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_stret_name,
eSymbolTypeCode);
const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType(
msg_forward_name, eSymbolTypeCode);
const Symbol *msg_forward_stret =
m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name,
eSymbolTypeCode);
if (class_getMethodImplementation)
m_impl_fn_addr =
class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress(
target);
if (class_getMethodImplementation_stret)
m_impl_stret_fn_addr =
class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress(
target);
if (msg_forward)
m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target);
if (msg_forward_stret)
m_msg_forward_stret_addr =
msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target);
// FIXME: Do some kind of logging here.
if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) {
// If we can't even find the ordinary get method implementation function,
// then we aren't going to be able to
// step through any method dispatches. Warn to that effect and get out of
// here.
if (process_sp->CanJIT()) {
process_sp->GetTarget().GetDebugger().GetErrorStream().Printf(
"Could not find implementation lookup function \"%s\""
" step in through ObjC method dispatch will not work.\n",
get_impl_name.AsCString());
}
return;
} else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) {
// It there is no stret return lookup function, assume that it is the same
// as the straight lookup:
m_impl_stret_fn_addr = m_impl_fn_addr;
// Also we will use the version of the lookup code that doesn't rely on the
// stret version of the function.
m_lookup_implementation_function_code =
g_lookup_implementation_no_stret_function_code;
} else {
m_lookup_implementation_function_code =
g_lookup_implementation_with_stret_function_code;
}
// Look up the addresses for the objc dispatch functions and cache
// them. For now I'm inspecting the symbol names dynamically to
// figure out how to dispatch to them. If it becomes more
// complicated than this we can turn the g_dispatch_functions char *
// array into a template table, and populate the DispatchFunction
// map from there.
for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) {
ConstString name_const_str(g_dispatch_functions[i].name);
const Symbol *msgSend_symbol =
m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str,
eSymbolTypeCode);
if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) {
// FIXME: Make g_dispatch_functions static table of
// DispatchFunctions, and have the map be address->index.
// Problem is we also need to lookup the dispatch function. For
// now we could have a side table of stret & non-stret dispatch
// functions. If that's as complex as it gets, we're fine.
lldb::addr_t sym_addr =
msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target);
m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i));
}
}
// Build our vtable dispatch handler here:
m_vtables_up.reset(new AppleObjCVTables(process_sp, m_objc_module_sp));
if (m_vtables_up)
m_vtables_up->ReadRegions();
}
lldb::addr_t
AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread,
ValueList &dispatch_values) {
ThreadSP thread_sp(thread.shared_from_this());
ExecutionContext exe_ctx(thread_sp);
DiagnosticManager diagnostics;
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
FunctionCaller *impl_function_caller = nullptr;
// Scope for mutex locker:
{
std::lock_guard<std::mutex> guard(m_impl_function_mutex);
// First stage is to make the ClangUtility to hold our injected function:
if (!m_impl_code) {
if (m_lookup_implementation_function_code != nullptr) {
Status error;
m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage(
m_lookup_implementation_function_code, eLanguageTypeObjC,
g_lookup_implementation_function_name, error));
if (error.Fail()) {
LLDB_LOGF(
log,
"Failed to get Utility Function for implementation lookup: %s.",
error.AsCString());
m_impl_code.reset();
return args_addr;
}
if (!m_impl_code->Install(diagnostics, exe_ctx)) {
if (log) {
LLDB_LOGF(log, "Failed to install implementation lookup.");
diagnostics.Dump(log);
}
m_impl_code.reset();
return args_addr;
}
} else {
LLDB_LOGF(log, "No method lookup implementation code.");
return LLDB_INVALID_ADDRESS;
}
// Next make the runner function for our implementation utility function.
ClangASTContext *clang_ast_context =
ClangASTContext::GetScratch(thread.GetProcess()->GetTarget());
if (!clang_ast_context)
return LLDB_INVALID_ADDRESS;
CompilerType clang_void_ptr_type =
clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
Status error;
impl_function_caller = m_impl_code->MakeFunctionCaller(
clang_void_ptr_type, dispatch_values, thread_sp, error);
if (error.Fail()) {
LLDB_LOGF(log,
"Error getting function caller for dispatch lookup: \"%s\".",
error.AsCString());
return args_addr;
}
} else {
impl_function_caller = m_impl_code->GetFunctionCaller();
}
}
diagnostics.Clear();
// Now write down the argument values for this particular call.
// This looks like it might be a race condition if other threads
// were calling into here, but actually it isn't because we allocate
// a new args structure for this call by passing args_addr =
// LLDB_INVALID_ADDRESS...
if (!impl_function_caller->WriteFunctionArguments(
exe_ctx, args_addr, dispatch_values, diagnostics)) {
if (log) {
LLDB_LOGF(log, "Error writing function arguments.");
diagnostics.Dump(log);
}
return args_addr;
}
return args_addr;
}
ThreadPlanSP
AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread,
bool stop_others) {
ThreadPlanSP ret_plan_sp;
lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
DispatchFunction this_dispatch;
bool found_it = false;
// First step is to look and see if we are in one of the known ObjC
// dispatch functions. We've already compiled a table of same, so
// consult it.
MsgsendMap::iterator pos;
pos = m_msgSend_map.find(curr_pc);
if (pos != m_msgSend_map.end()) {
this_dispatch = g_dispatch_functions[(*pos).second];
found_it = true;
}
// Next check to see if we are in a vtable region:
if (!found_it) {
uint32_t flags;
if (m_vtables_up) {
found_it = m_vtables_up->IsAddressInVTables(curr_pc, flags);
if (found_it) {
this_dispatch.name = "vtable";
this_dispatch.stret_return =
(flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) ==
AppleObjCVTables::eOBJC_TRAMPOLINE_STRET;
this_dispatch.is_super = false;
this_dispatch.is_super2 = false;
this_dispatch.fixedup = DispatchFunction::eFixUpFixed;
}
}
}
if (found_it) {
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
// We are decoding a method dispatch. First job is to pull the
// arguments out:
lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0);
const ABI *abi = nullptr;
ProcessSP process_sp(thread.CalculateProcess());
if (process_sp)
abi = process_sp->GetABI().get();
if (abi == nullptr)
return ret_plan_sp;
TargetSP target_sp(thread.CalculateTarget());
ClangASTContext *clang_ast_context = ClangASTContext::GetScratch(*target_sp);
if (!clang_ast_context)
return ret_plan_sp;
ValueList argument_values;
Value void_ptr_value;
CompilerType clang_void_ptr_type =
clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
void_ptr_value.SetValueType(Value::eValueTypeScalar);
// void_ptr_value.SetContext (Value::eContextTypeClangType,
// clang_void_ptr_type);
void_ptr_value.SetCompilerType(clang_void_ptr_type);
int obj_index;
int sel_index;
// If this is a struct return dispatch, then the first argument is
// the return struct pointer, and the object is the second, and
// the selector is the third. Otherwise the object is the first
// and the selector the second.
if (this_dispatch.stret_return) {
obj_index = 1;
sel_index = 2;
argument_values.PushValue(void_ptr_value);
argument_values.PushValue(void_ptr_value);
argument_values.PushValue(void_ptr_value);
} else {
obj_index = 0;
sel_index = 1;
argument_values.PushValue(void_ptr_value);
argument_values.PushValue(void_ptr_value);
}
bool success = abi->GetArgumentValues(thread, argument_values);
if (!success)
return ret_plan_sp;
lldb::addr_t obj_addr =
argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong();
if (obj_addr == 0x0) {
LLDB_LOGF(
log,
"Asked to step to dispatch to nil object, returning empty plan.");
return ret_plan_sp;
}
ExecutionContext exe_ctx(thread.shared_from_this());
Process *process = exe_ctx.GetProcessPtr();
// isa_addr will store the class pointer that the method is being
// dispatched to - so either the class directly or the super class
// if this is one of the objc_msgSendSuper flavors. That's mostly
// used to look up the class/selector pair in our cache.
lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t sel_addr =
argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong();
// Figure out the class this is being dispatched to and see if
// we've already cached this method call, If so we can push a
// run-to-address plan directly. Otherwise we have to figure out
// where the implementation lives.
if (this_dispatch.is_super) {
if (this_dispatch.is_super2) {
// In the objc_msgSendSuper2 case, we don't get the object
// directly, we get a structure containing the object and the
// class to which the super message is being sent. So we need
// to dig the super out of the class and use that.
Value super_value(*(argument_values.GetValueAtIndex(obj_index)));
super_value.GetScalar() += process->GetAddressByteSize();
super_value.ResolveValue(&exe_ctx);
if (super_value.GetScalar().IsValid()) {
// isa_value now holds the class pointer. The second word of the
// class pointer is the super-class pointer:
super_value.GetScalar() += process->GetAddressByteSize();
super_value.ResolveValue(&exe_ctx);
if (super_value.GetScalar().IsValid())
isa_addr = super_value.GetScalar().ULongLong();
else {
LLDB_LOGF(log, "Failed to extract the super class value from the "
"class in objc_super.");
}
} else {
LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
}
} else {
// In the objc_msgSendSuper case, we don't get the object
// directly, we get a two element structure containing the
// object and the super class to which the super message is
// being sent. So the class we want is the second element of
// this structure.
Value super_value(*(argument_values.GetValueAtIndex(obj_index)));
super_value.GetScalar() += process->GetAddressByteSize();
super_value.ResolveValue(&exe_ctx);
if (super_value.GetScalar().IsValid()) {
isa_addr = super_value.GetScalar().ULongLong();
} else {
LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
}
}
} else {
// In the direct dispatch case, the object->isa is the class pointer we
// want.
// This is a little cheesy, but since object->isa is the first field,
// making the object value a load address value and resolving it will get
// the pointer sized data pointed to by that value...
// Note, it isn't a fatal error not to be able to get the
// address from the object, since this might be a "tagged
// pointer" which isn't a real object, but rather some word
// length encoded dingus.
Value isa_value(*(argument_values.GetValueAtIndex(obj_index)));
isa_value.SetValueType(Value::eValueTypeLoadAddress);
isa_value.ResolveValue(&exe_ctx);
if (isa_value.GetScalar().IsValid()) {
isa_addr = isa_value.GetScalar().ULongLong();
} else {
LLDB_LOGF(log, "Failed to extract the isa value from object.");
}
}
// Okay, we've got the address of the class for which we're resolving this,
// let's see if it's in our cache:
lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS;
if (isa_addr != LLDB_INVALID_ADDRESS) {
if (log) {
LLDB_LOGF(log,
"Resolving call for class - 0x%" PRIx64
" and selector - 0x%" PRIx64,
isa_addr, sel_addr);
}
ObjCLanguageRuntime *objc_runtime =
ObjCLanguageRuntime::Get(*thread.GetProcess());
assert(objc_runtime != nullptr);
impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr);
}
if (impl_addr != LLDB_INVALID_ADDRESS) {
// Yup, it was in the cache, so we can run to that address directly.
LLDB_LOGF(log, "Found implementation address in cache: 0x%" PRIx64,
impl_addr);
ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(thread, impl_addr,
stop_others);
} else {
// We haven't seen this class/selector pair yet. Look it up.
StreamString errors;
Address impl_code_address;
ValueList dispatch_values;
// We've will inject a little function in the target that takes the
// object, selector and some flags,
// and figures out the implementation. Looks like:
// void *__lldb_objc_find_implementation_for_selector (void *object,
// void *sel,
// int is_stret,
// int is_super,
// int is_super2,
// int is_fixup,
// int is_fixed,
// int debug)
// So set up the arguments for that call.
dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index)));
dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index)));
Value flag_value;
CompilerType clang_int_type =
clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(
lldb::eEncodingSint, 32);
flag_value.SetValueType(Value::eValueTypeScalar);
// flag_value.SetContext (Value::eContextTypeClangType, clang_int_type);
flag_value.SetCompilerType(clang_int_type);
if (this_dispatch.stret_return)
flag_value.GetScalar() = 1;
else
flag_value.GetScalar() = 0;
dispatch_values.PushValue(flag_value);
if (this_dispatch.is_super)
flag_value.GetScalar() = 1;
else
flag_value.GetScalar() = 0;
dispatch_values.PushValue(flag_value);
if (this_dispatch.is_super2)
flag_value.GetScalar() = 1;
else
flag_value.GetScalar() = 0;
dispatch_values.PushValue(flag_value);
switch (this_dispatch.fixedup) {
case DispatchFunction::eFixUpNone:
flag_value.GetScalar() = 0;
dispatch_values.PushValue(flag_value);
dispatch_values.PushValue(flag_value);
break;
case DispatchFunction::eFixUpFixed:
flag_value.GetScalar() = 1;
dispatch_values.PushValue(flag_value);
flag_value.GetScalar() = 1;
dispatch_values.PushValue(flag_value);
break;
case DispatchFunction::eFixUpToFix:
flag_value.GetScalar() = 1;
dispatch_values.PushValue(flag_value);
flag_value.GetScalar() = 0;
dispatch_values.PushValue(flag_value);
break;
}
if (log && log->GetVerbose())
flag_value.GetScalar() = 1;
else
flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done.
dispatch_values.PushValue(flag_value);
// The step through code might have to fill in the cache, so it
// is not safe to run only one thread. So we override the
// stop_others value passed in to us here:
const bool trampoline_stop_others = false;
ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughObjCTrampoline>(
thread, this, dispatch_values, isa_addr, sel_addr,
trampoline_stop_others);
if (log) {
StreamString s;
ret_plan_sp->GetDescription(&s, eDescriptionLevelFull);
LLDB_LOGF(log, "Using ObjC step plan: %s.\n", s.GetData());
}
}
}
return ret_plan_sp;
}
FunctionCaller *
AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() {
return m_impl_code->GetFunctionCaller();
}