//===-- AppleObjCTrampolineHandler.cpp ----------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lldb/lldb-python.h"
#include "AppleObjCTrampolineHandler.h"
// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "AppleThreadPlanStepThroughObjCTrampoline.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/ConstString.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/Value.h"
#include "lldb/Expression/ClangExpression.h"
#include "lldb/Expression/ClangFunction.h"
#include "lldb/Expression/ClangUtilityFunction.h"
#include "lldb/Host/FileSpec.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Target/ObjCLanguageRuntime.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
#include "llvm/ADT/STLExtras.h"
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_function_code = NULL;
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, void *sel); \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 *reciever; \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\
void *class_ptr = (void *) [(id) object class]; \n\
if (class_ptr == object) \n\
{ \n\
struct __lldb_objc_class *class_as_class_struct = (struct __lldb_objc_class *) class_ptr; \n\
if (debug) \n\
printf (\"Found a class object, need to return the meta class 0x%p -> 0x%p\\n\", \n\
class_ptr, class_as_class_struct->isa); \n\
return_struct.class_addr = class_as_class_struct->isa; \n\
} \n\
else \n\
{ \n\
if (debug) \n\
printf (\"[object class] returned: 0x%p.\\n\", class_ptr); \n\
return_struct.class_addr = class_ptr; \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: 0x%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 = class_getMethodImplementation_stret (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
} \n\
else \n\
{ \n\
return_struct.impl_addr = class_getMethodImplementation (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
} \n\
if (debug) \n\
printf (\"\\n*** Returning implementation: 0x%p.\\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 * 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 *reciever; \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\
void *class_ptr = (void *) [(id) object class]; \n\
if (class_ptr == object) \n\
{ \n\
struct __lldb_objc_class *class_as_class_struct = (struct __lldb_objc_class *) class_ptr; \n\
if (debug) \n\
printf (\"Found a class object, need to return the meta class 0x%p -> 0x%p\\n\", \n\
class_ptr, class_as_class_struct->isa); \n\
return_struct.class_addr = class_as_class_struct->isa; \n\
} \n\
else \n\
{ \n\
if (debug) \n\
printf (\"[object class] returned: 0x%p.\\n\", class_ptr); \n\
return_struct.class_addr = class_ptr; \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: 0x%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 = class_getMethodImplementation (return_struct.class_addr, \n\
return_struct.sel_addr); \n\
if (debug) \n\
printf (\"\\n*** Returning implementation: 0x%p.\\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];
Process *process = m_owner->GetProcess();
DataExtractor data(memory_buffer, sizeof(memory_buffer),
process->GetByteOrder(),
process->GetAddressByteSize());
size_t actual_size = 8 + process->GetAddressByteSize();
Error error;
size_t bytes_read = process->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->GetByteOrder(),
process->GetAddressByteSize());
bytes_read = process->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_sp (process_sp),
m_trampoline_header (LLDB_INVALID_ADDRESS),
m_trampolines_changed_bp_id (LLDB_INVALID_BREAK_ID),
m_objc_module_sp (objc_module_sp)
{
}
AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables()
{
if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID)
m_process_sp->GetTarget().RemoveBreakpointByID (m_trampolines_changed_bp_id);
}
bool
AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols ()
{
if (m_trampoline_header != LLDB_INVALID_ADDRESS)
return true;
Target &target = m_process_sp->GetTarget();
const ModuleList &target_modules = target.GetImages();
Mutex::Locker modules_locker(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 (m_process_sp->GetObjCLanguageRuntime()->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 != NULL)
{
if (!trampoline_symbol->GetAddress().IsValid())
return false;
m_trampoline_header = trampoline_symbol->GetAddress().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 != NULL)
{
if (!changed_symbol->GetAddress().IsValid())
return false;
lldb::addr_t changed_addr = changed_symbol->GetAddress().GetOpcodeLoadAddress (&target);
if (changed_addr != LLDB_INVALID_ADDRESS)
{
BreakpointSP trampolines_changed_bp_sp = target.CreateBreakpoint (changed_addr, true);
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 = process->GetTarget().GetScratchClangASTContext();
ValueList argument_values;
Value input_value;
ClangASTType 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.SetClangType (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.
Error error;
DataExtractor data;
error = argument_values.GetValueAtIndex(0)->GetValueAsData (&exe_ctx,
data,
0,
NULL);
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;
Error error;
lldb::addr_t region_addr = m_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)
{
if (!m_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);
log->Printf("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_sp (process_sp),
m_objc_module_sp (objc_module_sp),
m_impl_fn_addr (LLDB_INVALID_ADDRESS),
m_impl_stret_fn_addr (LLDB_INVALID_ADDRESS),
m_msg_forward_addr (LLDB_INVALID_ADDRESS)
{
// 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 = m_process_sp ? &m_process_sp->GetTarget() : NULL;
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.
g_lookup_implementation_function_code = g_lookup_implementation_no_stret_function_code;
}
else
{
g_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)
{
// 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->GetAddress().GetOpcodeLoadAddress(target);
m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i));
}
}
// Build our vtable dispatch handler here:
m_vtables_ap.reset(new AppleObjCVTables(process_sp, m_objc_module_sp));
if (m_vtables_ap.get())
m_vtables_ap->ReadRegions();
}
lldb::addr_t
AppleObjCTrampolineHandler::SetupDispatchFunction (Thread &thread, ValueList &dispatch_values)
{
ExecutionContext exe_ctx (thread.shared_from_this());
Address impl_code_address;
StreamString errors;
Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
// Scope for mutex locker:
{
Mutex::Locker locker(m_impl_function_mutex);
// First stage is to make the ClangUtility to hold our injected function:
#define USE_BUILTIN_FUNCTION 0 // Define this to 1 and we will use the get_implementation function found in the target.
// This is useful for debugging additions to the get_impl function 'cause you don't have
// to bother with string-ifying the code into g_lookup_implementation_function_code.
if (USE_BUILTIN_FUNCTION)
{
ConstString our_utility_function_name("__lldb_objc_find_implementation_for_selector");
SymbolContextList sc_list;
exe_ctx.GetTargetRef().GetImages().FindSymbolsWithNameAndType (our_utility_function_name, eSymbolTypeCode, sc_list);
if (sc_list.GetSize() == 1)
{
SymbolContext sc;
sc_list.GetContextAtIndex(0, sc);
if (sc.symbol != NULL)
impl_code_address = sc.symbol->GetAddress();
//lldb::addr_t addr = impl_code_address.GetOpcodeLoadAddress (exe_ctx.GetTargetPtr());
//printf ("Getting address for our_utility_function: 0x%" PRIx64 ".\n", addr);
}
else
{
//printf ("Could not find implementation function address.\n");
return args_addr;
}
}
else if (!m_impl_code.get())
{
if (g_lookup_implementation_function_code != NULL)
{
m_impl_code.reset (new ClangUtilityFunction (g_lookup_implementation_function_code,
g_lookup_implementation_function_name));
if (!m_impl_code->Install(errors, exe_ctx))
{
if (log)
log->Printf ("Failed to install implementation lookup: %s.", errors.GetData());
m_impl_code.reset();
return args_addr;
}
}
else
{
if (log)
log->Printf("No method lookup implementation code.");
errors.Printf ("No method lookup implementation code found.");
return LLDB_INVALID_ADDRESS;
}
impl_code_address.Clear();
impl_code_address.SetOffset(m_impl_code->StartAddress());
}
else
{
impl_code_address.Clear();
impl_code_address.SetOffset(m_impl_code->StartAddress());
}
// Next make the runner function for our implementation utility function.
if (!m_impl_function.get())
{
ClangASTContext *clang_ast_context = thread.GetProcess()->GetTarget().GetScratchClangASTContext();
ClangASTType clang_void_ptr_type = clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
m_impl_function.reset(new ClangFunction (thread,
clang_void_ptr_type,
impl_code_address,
dispatch_values));
errors.Clear();
unsigned num_errors = m_impl_function->CompileFunction(errors);
if (num_errors)
{
if (log)
log->Printf ("Error compiling function: \"%s\".", errors.GetData());
return args_addr;
}
errors.Clear();
if (!m_impl_function->WriteFunctionWrapper(exe_ctx, errors))
{
if (log)
log->Printf ("Error Inserting function: \"%s\".", errors.GetData());
return args_addr;
}
}
}
errors.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 (!m_impl_function->WriteFunctionArguments (exe_ctx, args_addr, impl_code_address, dispatch_values, errors))
{
if (log)
log->Printf ("Error writing function arguments: \"%s\".", errors.GetData());
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_ap.get())
{
found_it = m_vtables_ap->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 = NULL;
ProcessSP process_sp (thread.CalculateProcess());
if (process_sp)
abi = process_sp->GetABI().get();
if (abi == NULL)
return ret_plan_sp;
TargetSP target_sp (thread.CalculateTarget());
ClangASTContext *clang_ast_context = target_sp->GetScratchClangASTContext();
ValueList argument_values;
Value void_ptr_value;
ClangASTType 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.SetClangType (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)
{
if (log)
log->Printf("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
{
if (log)
log->Printf("Failed to extract the super class value from the class in objc_super.");
}
}
else
{
if (log)
log->Printf("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
{
if (log)
log->Printf("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
{
if (log)
log->Printf("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)
{
log->Printf("Resolving call for class - 0x%" PRIx64 " and selector - 0x%" PRIx64,
isa_addr, sel_addr);
}
ObjCLanguageRuntime *objc_runtime = m_process_sp->GetObjCLanguageRuntime ();
assert(objc_runtime != NULL);
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.
if (log)
log->Printf ("Found implementation address in cache: 0x%" PRIx64, impl_addr);
ret_plan_sp.reset (new 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;
ClangASTType 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.SetClangType (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.reset (new AppleThreadPlanStepThroughObjCTrampoline (thread,
this,
dispatch_values,
isa_addr,
sel_addr,
trampoline_stop_others));
if (log)
{
StreamString s;
ret_plan_sp->GetDescription(&s, eDescriptionLevelFull);
log->Printf("Using ObjC step plan: %s.\n", s.GetData());
}
}
}
return ret_plan_sp;
}
ClangFunction *
AppleObjCTrampolineHandler::GetLookupImplementationWrapperFunction ()
{
return m_impl_function.get();
}