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//===-- FuncUnwinders.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 "lldb/Symbol/FuncUnwinders.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/AddressRange.h"
#include "lldb/Symbol/ArmUnwindInfo.h"
#include "lldb/Symbol/CompactUnwindInfo.h"
#include "lldb/Symbol/DWARFCallFrameInfo.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Symbol/UnwindTable.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/RegisterNumber.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/UnwindAssembly.h"
#include <memory>
using namespace lldb;
using namespace lldb_private;
/// constructor
FuncUnwinders::FuncUnwinders(UnwindTable &unwind_table, AddressRange range)
: m_unwind_table(unwind_table), m_range(range), m_mutex(),
m_unwind_plan_assembly_sp(), m_unwind_plan_eh_frame_sp(),
m_unwind_plan_eh_frame_augmented_sp(), m_unwind_plan_compact_unwind(),
m_unwind_plan_arm_unwind_sp(), m_unwind_plan_fast_sp(),
m_unwind_plan_arch_default_sp(),
m_unwind_plan_arch_default_at_func_entry_sp(),
m_tried_unwind_plan_assembly(false), m_tried_unwind_plan_eh_frame(false),
m_tried_unwind_plan_debug_frame(false),
m_tried_unwind_plan_eh_frame_augmented(false),
m_tried_unwind_plan_debug_frame_augmented(false),
m_tried_unwind_plan_compact_unwind(false),
m_tried_unwind_plan_arm_unwind(false),
m_tried_unwind_plan_symbol_file(false), m_tried_unwind_fast(false),
m_tried_unwind_arch_default(false),
m_tried_unwind_arch_default_at_func_entry(false),
m_first_non_prologue_insn() {}
/// destructor
FuncUnwinders::~FuncUnwinders() {}
UnwindPlanSP FuncUnwinders::GetUnwindPlanAtCallSite(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (UnwindPlanSP plan_sp = GetEHFrameUnwindPlan(target))
return plan_sp;
if (UnwindPlanSP plan_sp = GetDebugFrameUnwindPlan(target))
return plan_sp;
if (UnwindPlanSP plan_sp = GetCompactUnwindUnwindPlan(target))
return plan_sp;
if (UnwindPlanSP plan_sp = GetArmUnwindUnwindPlan(target))
return plan_sp;
return nullptr;
}
UnwindPlanSP FuncUnwinders::GetCompactUnwindUnwindPlan(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_compact_unwind.size() > 0)
return m_unwind_plan_compact_unwind[0]; // FIXME support multiple compact
// unwind plans for one func
if (m_tried_unwind_plan_compact_unwind)
return UnwindPlanSP();
m_tried_unwind_plan_compact_unwind = true;
if (m_range.GetBaseAddress().IsValid()) {
Address current_pc(m_range.GetBaseAddress());
CompactUnwindInfo *compact_unwind = m_unwind_table.GetCompactUnwindInfo();
if (compact_unwind) {
UnwindPlanSP unwind_plan_sp(new UnwindPlan(lldb::eRegisterKindGeneric));
if (compact_unwind->GetUnwindPlan(target, current_pc, *unwind_plan_sp)) {
m_unwind_plan_compact_unwind.push_back(unwind_plan_sp);
return m_unwind_plan_compact_unwind[0]; // FIXME support multiple
// compact unwind plans for one
// func
}
}
}
return UnwindPlanSP();
}
UnwindPlanSP FuncUnwinders::GetEHFrameUnwindPlan(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_eh_frame_sp.get() || m_tried_unwind_plan_eh_frame)
return m_unwind_plan_eh_frame_sp;
m_tried_unwind_plan_eh_frame = true;
if (m_range.GetBaseAddress().IsValid()) {
DWARFCallFrameInfo *eh_frame = m_unwind_table.GetEHFrameInfo();
if (eh_frame) {
m_unwind_plan_eh_frame_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!eh_frame->GetUnwindPlan(m_range, *m_unwind_plan_eh_frame_sp))
m_unwind_plan_eh_frame_sp.reset();
}
}
return m_unwind_plan_eh_frame_sp;
}
UnwindPlanSP FuncUnwinders::GetDebugFrameUnwindPlan(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_debug_frame_sp || m_tried_unwind_plan_debug_frame)
return m_unwind_plan_debug_frame_sp;
m_tried_unwind_plan_debug_frame = true;
if (m_range.GetBaseAddress().IsValid()) {
DWARFCallFrameInfo *debug_frame = m_unwind_table.GetDebugFrameInfo();
if (debug_frame) {
m_unwind_plan_debug_frame_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!debug_frame->GetUnwindPlan(m_range, *m_unwind_plan_debug_frame_sp))
m_unwind_plan_debug_frame_sp.reset();
}
}
return m_unwind_plan_debug_frame_sp;
}
UnwindPlanSP FuncUnwinders::GetArmUnwindUnwindPlan(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_arm_unwind_sp.get() || m_tried_unwind_plan_arm_unwind)
return m_unwind_plan_arm_unwind_sp;
m_tried_unwind_plan_arm_unwind = true;
if (m_range.GetBaseAddress().IsValid()) {
Address current_pc(m_range.GetBaseAddress());
ArmUnwindInfo *arm_unwind_info = m_unwind_table.GetArmUnwindInfo();
if (arm_unwind_info) {
m_unwind_plan_arm_unwind_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!arm_unwind_info->GetUnwindPlan(target, current_pc,
*m_unwind_plan_arm_unwind_sp))
m_unwind_plan_arm_unwind_sp.reset();
}
}
return m_unwind_plan_arm_unwind_sp;
}
namespace {
class RegisterContextToInfo: public SymbolFile::RegisterInfoResolver {
public:
RegisterContextToInfo(RegisterContext &ctx) : m_ctx(ctx) {}
const RegisterInfo *ResolveName(llvm::StringRef name) const {
return m_ctx.GetRegisterInfoByName(name);
}
const RegisterInfo *ResolveNumber(lldb::RegisterKind kind,
uint32_t number) const {
return m_ctx.GetRegisterInfo(kind, number);
}
private:
RegisterContext &m_ctx;
};
} // namespace
UnwindPlanSP FuncUnwinders::GetSymbolFileUnwindPlan(Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_symbol_file_sp.get() || m_tried_unwind_plan_symbol_file)
return m_unwind_plan_symbol_file_sp;
m_tried_unwind_plan_symbol_file = true;
if (SymbolFile *symfile = m_unwind_table.GetSymbolFile()) {
m_unwind_plan_symbol_file_sp = symfile->GetUnwindPlan(
m_range.GetBaseAddress(),
RegisterContextToInfo(*thread.GetRegisterContext()));
}
return m_unwind_plan_symbol_file_sp;
}
UnwindPlanSP FuncUnwinders::GetEHFrameAugmentedUnwindPlan(Target &target,
Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_eh_frame_augmented_sp.get() ||
m_tried_unwind_plan_eh_frame_augmented)
return m_unwind_plan_eh_frame_augmented_sp;
// Only supported on x86 architectures where we get eh_frame from the
// compiler that describes the prologue instructions perfectly, and sometimes
// the epilogue instructions too.
if (target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_32_i386 &&
target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_64_x86_64 &&
target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_64_x86_64h) {
m_tried_unwind_plan_eh_frame_augmented = true;
return m_unwind_plan_eh_frame_augmented_sp;
}
m_tried_unwind_plan_eh_frame_augmented = true;
UnwindPlanSP eh_frame_plan = GetEHFrameUnwindPlan(target);
if (!eh_frame_plan)
return m_unwind_plan_eh_frame_augmented_sp;
m_unwind_plan_eh_frame_augmented_sp =
std::make_shared<UnwindPlan>(*eh_frame_plan);
// Augment the eh_frame instructions with epilogue descriptions if necessary
// so the UnwindPlan can be used at any instruction in the function.
UnwindAssemblySP assembly_profiler_sp(GetUnwindAssemblyProfiler(target));
if (assembly_profiler_sp) {
if (!assembly_profiler_sp->AugmentUnwindPlanFromCallSite(
m_range, thread, *m_unwind_plan_eh_frame_augmented_sp)) {
m_unwind_plan_eh_frame_augmented_sp.reset();
}
} else {
m_unwind_plan_eh_frame_augmented_sp.reset();
}
return m_unwind_plan_eh_frame_augmented_sp;
}
UnwindPlanSP FuncUnwinders::GetDebugFrameAugmentedUnwindPlan(Target &target,
Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_debug_frame_augmented_sp.get() ||
m_tried_unwind_plan_debug_frame_augmented)
return m_unwind_plan_debug_frame_augmented_sp;
// Only supported on x86 architectures where we get debug_frame from the
// compiler that describes the prologue instructions perfectly, and sometimes
// the epilogue instructions too.
if (target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_32_i386 &&
target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_64_x86_64 &&
target.GetArchitecture().GetCore() != ArchSpec::eCore_x86_64_x86_64h) {
m_tried_unwind_plan_debug_frame_augmented = true;
return m_unwind_plan_debug_frame_augmented_sp;
}
m_tried_unwind_plan_debug_frame_augmented = true;
UnwindPlanSP debug_frame_plan = GetDebugFrameUnwindPlan(target);
if (!debug_frame_plan)
return m_unwind_plan_debug_frame_augmented_sp;
m_unwind_plan_debug_frame_augmented_sp =
std::make_shared<UnwindPlan>(*debug_frame_plan);
// Augment the debug_frame instructions with epilogue descriptions if
// necessary so the UnwindPlan can be used at any instruction in the
// function.
UnwindAssemblySP assembly_profiler_sp(GetUnwindAssemblyProfiler(target));
if (assembly_profiler_sp) {
if (!assembly_profiler_sp->AugmentUnwindPlanFromCallSite(
m_range, thread, *m_unwind_plan_debug_frame_augmented_sp)) {
m_unwind_plan_debug_frame_augmented_sp.reset();
}
} else
m_unwind_plan_debug_frame_augmented_sp.reset();
return m_unwind_plan_debug_frame_augmented_sp;
}
UnwindPlanSP FuncUnwinders::GetAssemblyUnwindPlan(Target &target,
Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_assembly_sp.get() || m_tried_unwind_plan_assembly ||
!m_unwind_table.GetAllowAssemblyEmulationUnwindPlans()) {
return m_unwind_plan_assembly_sp;
}
m_tried_unwind_plan_assembly = true;
UnwindAssemblySP assembly_profiler_sp(GetUnwindAssemblyProfiler(target));
if (assembly_profiler_sp) {
m_unwind_plan_assembly_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!assembly_profiler_sp->GetNonCallSiteUnwindPlanFromAssembly(
m_range, thread, *m_unwind_plan_assembly_sp)) {
m_unwind_plan_assembly_sp.reset();
}
}
return m_unwind_plan_assembly_sp;
}
// This method compares the pc unwind rule in the first row of two UnwindPlans.
// If they have the same way of getting the pc value (e.g. "CFA - 8" + "CFA is
// sp"), then it will return LazyBoolTrue.
LazyBool FuncUnwinders::CompareUnwindPlansForIdenticalInitialPCLocation(
Thread &thread, const UnwindPlanSP &a, const UnwindPlanSP &b) {
LazyBool plans_are_identical = eLazyBoolCalculate;
RegisterNumber pc_reg(thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
uint32_t pc_reg_lldb_regnum = pc_reg.GetAsKind(eRegisterKindLLDB);
if (a.get() && b.get()) {
UnwindPlan::RowSP a_first_row = a->GetRowAtIndex(0);
UnwindPlan::RowSP b_first_row = b->GetRowAtIndex(0);
if (a_first_row.get() && b_first_row.get()) {
UnwindPlan::Row::RegisterLocation a_pc_regloc;
UnwindPlan::Row::RegisterLocation b_pc_regloc;
a_first_row->GetRegisterInfo(pc_reg_lldb_regnum, a_pc_regloc);
b_first_row->GetRegisterInfo(pc_reg_lldb_regnum, b_pc_regloc);
plans_are_identical = eLazyBoolYes;
if (a_first_row->GetCFAValue() != b_first_row->GetCFAValue()) {
plans_are_identical = eLazyBoolNo;
}
if (a_pc_regloc != b_pc_regloc) {
plans_are_identical = eLazyBoolNo;
}
}
}
return plans_are_identical;
}
UnwindPlanSP FuncUnwinders::GetUnwindPlanAtNonCallSite(Target &target,
Thread &thread) {
UnwindPlanSP eh_frame_sp = GetEHFrameUnwindPlan(target);
if (!eh_frame_sp)
eh_frame_sp = GetDebugFrameUnwindPlan(target);
UnwindPlanSP arch_default_at_entry_sp =
GetUnwindPlanArchitectureDefaultAtFunctionEntry(thread);
UnwindPlanSP arch_default_sp = GetUnwindPlanArchitectureDefault(thread);
UnwindPlanSP assembly_sp = GetAssemblyUnwindPlan(target, thread);
// This point of this code is to detect when a function is using a non-
// standard ABI, and the eh_frame correctly describes that alternate ABI.
// This is addressing a specific situation on x86_64 linux systems where one
// function in a library pushes a value on the stack and jumps to another
// function. So using an assembly instruction based unwind will not work
// when you're in the second function - the stack has been modified in a non-
// ABI way. But we have eh_frame that correctly describes how to unwind from
// this location. So we're looking to see if the initial pc register save
// location from the eh_frame is different from the assembly unwind, the arch
// default unwind, and the arch default at initial function entry.
//
// We may have eh_frame that describes the entire function -- or we may have
// eh_frame that only describes the unwind after the prologue has executed --
// so we need to check both the arch default (once the prologue has executed)
// and the arch default at initial function entry. And we may be running on
// a target where we have only some of the assembly/arch default unwind plans
// available.
if (CompareUnwindPlansForIdenticalInitialPCLocation(
thread, eh_frame_sp, arch_default_at_entry_sp) == eLazyBoolNo &&
CompareUnwindPlansForIdenticalInitialPCLocation(
thread, eh_frame_sp, arch_default_sp) == eLazyBoolNo &&
CompareUnwindPlansForIdenticalInitialPCLocation(
thread, assembly_sp, arch_default_sp) == eLazyBoolNo) {
return eh_frame_sp;
}
if (UnwindPlanSP plan_sp = GetEHFrameAugmentedUnwindPlan(target, thread))
return plan_sp;
if (UnwindPlanSP plan_sp = GetDebugFrameAugmentedUnwindPlan(target, thread))
return plan_sp;
return assembly_sp;
}
UnwindPlanSP FuncUnwinders::GetUnwindPlanFastUnwind(Target &target,
Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_fast_sp.get() || m_tried_unwind_fast)
return m_unwind_plan_fast_sp;
m_tried_unwind_fast = true;
UnwindAssemblySP assembly_profiler_sp(GetUnwindAssemblyProfiler(target));
if (assembly_profiler_sp) {
m_unwind_plan_fast_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!assembly_profiler_sp->GetFastUnwindPlan(m_range, thread,
*m_unwind_plan_fast_sp)) {
m_unwind_plan_fast_sp.reset();
}
}
return m_unwind_plan_fast_sp;
}
UnwindPlanSP FuncUnwinders::GetUnwindPlanArchitectureDefault(Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_arch_default_sp.get() || m_tried_unwind_arch_default)
return m_unwind_plan_arch_default_sp;
m_tried_unwind_arch_default = true;
Address current_pc;
ProcessSP process_sp(thread.CalculateProcess());
if (process_sp) {
ABI *abi = process_sp->GetABI().get();
if (abi) {
m_unwind_plan_arch_default_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!abi->CreateDefaultUnwindPlan(*m_unwind_plan_arch_default_sp)) {
m_unwind_plan_arch_default_sp.reset();
}
}
}
return m_unwind_plan_arch_default_sp;
}
UnwindPlanSP
FuncUnwinders::GetUnwindPlanArchitectureDefaultAtFunctionEntry(Thread &thread) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_unwind_plan_arch_default_at_func_entry_sp.get() ||
m_tried_unwind_arch_default_at_func_entry)
return m_unwind_plan_arch_default_at_func_entry_sp;
m_tried_unwind_arch_default_at_func_entry = true;
Address current_pc;
ProcessSP process_sp(thread.CalculateProcess());
if (process_sp) {
ABI *abi = process_sp->GetABI().get();
if (abi) {
m_unwind_plan_arch_default_at_func_entry_sp =
std::make_shared<UnwindPlan>(lldb::eRegisterKindGeneric);
if (!abi->CreateFunctionEntryUnwindPlan(
*m_unwind_plan_arch_default_at_func_entry_sp)) {
m_unwind_plan_arch_default_at_func_entry_sp.reset();
}
}
}
return m_unwind_plan_arch_default_at_func_entry_sp;
}
Address &FuncUnwinders::GetFirstNonPrologueInsn(Target &target) {
std::lock_guard<std::recursive_mutex> guard(m_mutex);
if (m_first_non_prologue_insn.IsValid())
return m_first_non_prologue_insn;
ExecutionContext exe_ctx(target.shared_from_this(), false);
UnwindAssemblySP assembly_profiler_sp(GetUnwindAssemblyProfiler(target));
if (assembly_profiler_sp)
assembly_profiler_sp->FirstNonPrologueInsn(m_range, exe_ctx,
m_first_non_prologue_insn);
return m_first_non_prologue_insn;
}
const Address &FuncUnwinders::GetFunctionStartAddress() const {
return m_range.GetBaseAddress();
}
lldb::UnwindAssemblySP
FuncUnwinders::GetUnwindAssemblyProfiler(Target &target) {
UnwindAssemblySP assembly_profiler_sp;
if (ArchSpec arch = m_unwind_table.GetArchitecture()) {
arch.MergeFrom(target.GetArchitecture());
assembly_profiler_sp = UnwindAssembly::FindPlugin(arch);
}
return assembly_profiler_sp;
}
Address FuncUnwinders::GetLSDAAddress(Target &target) {
Address lsda_addr;
UnwindPlanSP unwind_plan_sp = GetEHFrameUnwindPlan(target);
if (unwind_plan_sp.get() == nullptr) {
unwind_plan_sp = GetCompactUnwindUnwindPlan(target);
}
if (unwind_plan_sp.get() && unwind_plan_sp->GetLSDAAddress().IsValid()) {
lsda_addr = unwind_plan_sp->GetLSDAAddress();
}
return lsda_addr;
}
Address FuncUnwinders::GetPersonalityRoutinePtrAddress(Target &target) {
Address personality_addr;
UnwindPlanSP unwind_plan_sp = GetEHFrameUnwindPlan(target);
if (unwind_plan_sp.get() == nullptr) {
unwind_plan_sp = GetCompactUnwindUnwindPlan(target);
}
if (unwind_plan_sp.get() &&
unwind_plan_sp->GetPersonalityFunctionPtr().IsValid()) {
personality_addr = unwind_plan_sp->GetPersonalityFunctionPtr();
}
return personality_addr;
}