lldb/source/Symbol/FuncUnwinders.cpp

//===-- FuncUnwinders.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/Core/AddressRange.h"
#include "lldb/Core/Address.h"
#include "lldb/Symbol/FuncUnwinders.h"
#include "lldb/Symbol/ArmUnwindInfo.h"
#include "lldb/Symbol/DWARFCallFrameInfo.h"
#include "lldb/Symbol/CompactUnwindInfo.h"
#include "lldb/Symbol/ObjectFile.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/Thread.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/UnwindAssembly.h"
#include "lldb/Utility/RegisterNumber.h"

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_eh_frame_augmented(false),
      m_tried_unwind_plan_compact_unwind(false),
      m_tried_unwind_plan_arm_unwind(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, int current_offset)
{
    std::lock_guard<std::recursive_mutex> guard(m_mutex);

    UnwindPlanSP unwind_plan_sp = GetEHFrameUnwindPlan (target, current_offset);
    if (unwind_plan_sp)
        return unwind_plan_sp;

    unwind_plan_sp = GetCompactUnwindUnwindPlan (target, current_offset);
    if (unwind_plan_sp)
        return unwind_plan_sp;

    unwind_plan_sp = GetArmUnwindUnwindPlan (target, current_offset);
    if (unwind_plan_sp)
        return unwind_plan_sp;

    return nullptr;
}

UnwindPlanSP
FuncUnwinders::GetCompactUnwindUnwindPlan (Target &target, int current_offset)
{
    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();

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_plan_compact_unwind = true;
    if (m_range.GetBaseAddress().IsValid())
    {
        Address current_pc (m_range.GetBaseAddress ());
        if (current_offset != -1)
            current_pc.SetOffset (current_pc.GetOffset() + current_offset);
        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, int current_offset)
{
    if (m_unwind_plan_eh_frame_sp.get() || m_tried_unwind_plan_eh_frame)
        return m_unwind_plan_eh_frame_sp;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_plan_eh_frame = true;
    if (m_range.GetBaseAddress().IsValid())
    {
        Address current_pc (m_range.GetBaseAddress ());
        if (current_offset != -1)
            current_pc.SetOffset (current_pc.GetOffset() + current_offset);
        DWARFCallFrameInfo *eh_frame = m_unwind_table.GetEHFrameInfo();
        if (eh_frame)
        {
            m_unwind_plan_eh_frame_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
            if (!eh_frame->GetUnwindPlan (current_pc, *m_unwind_plan_eh_frame_sp))
                m_unwind_plan_eh_frame_sp.reset();
        }
    }
    return m_unwind_plan_eh_frame_sp;
}

UnwindPlanSP
FuncUnwinders::GetArmUnwindUnwindPlan (Target &target, int current_offset)
{
    if (m_unwind_plan_arm_unwind_sp.get() || m_tried_unwind_plan_arm_unwind)
        return m_unwind_plan_arm_unwind_sp;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_plan_arm_unwind = true;
    if (m_range.GetBaseAddress().IsValid())
    {
        Address current_pc (m_range.GetBaseAddress ());
        if (current_offset != -1)
            current_pc.SetOffset (current_pc.GetOffset() + current_offset);
        ArmUnwindInfo *arm_unwind_info = m_unwind_table.GetArmUnwindInfo();
        if (arm_unwind_info)
        {
            m_unwind_plan_arm_unwind_sp.reset (new 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;
}

UnwindPlanSP
FuncUnwinders::GetEHFrameAugmentedUnwindPlan (Target &target, Thread &thread, int current_offset)
{
    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;
    }

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_plan_eh_frame_augmented = true;

    UnwindPlanSP eh_frame_plan = GetEHFrameUnwindPlan (target, current_offset);
    if (!eh_frame_plan)
        return m_unwind_plan_eh_frame_augmented_sp;

    m_unwind_plan_eh_frame_augmented_sp.reset(new 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::GetAssemblyUnwindPlan (Target &target, Thread &thread, int current_offset)
{
    if (m_unwind_plan_assembly_sp.get() 
        || m_tried_unwind_plan_assembly 
        || m_unwind_table.GetAllowAssemblyEmulationUnwindPlans () == false)
    {
        return m_unwind_plan_assembly_sp;
    }

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_plan_assembly = true;

    UnwindAssemblySP assembly_profiler_sp (GetUnwindAssemblyProfiler(target));
    if (assembly_profiler_sp)
    {
        m_unwind_plan_assembly_sp.reset (new 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, int current_offset)
{
    UnwindPlanSP eh_frame_sp = GetEHFrameUnwindPlan (target, current_offset);
    UnwindPlanSP arch_default_at_entry_sp = GetUnwindPlanArchitectureDefaultAtFunctionEntry (thread);
    UnwindPlanSP arch_default_sp = GetUnwindPlanArchitectureDefault (thread);
    UnwindPlanSP assembly_sp = GetAssemblyUnwindPlan (target, thread, current_offset);

    // 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;
    }

    UnwindPlanSP eh_frame_augmented_sp = GetEHFrameAugmentedUnwindPlan (target, thread, current_offset);
    if (eh_frame_augmented_sp)
    {
        return eh_frame_augmented_sp;
    }

    return assembly_sp;
}

UnwindPlanSP
FuncUnwinders::GetUnwindPlanFastUnwind (Target& target, Thread& thread)
{
    if (m_unwind_plan_fast_sp.get() || m_tried_unwind_fast)
        return m_unwind_plan_fast_sp;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    m_tried_unwind_fast = true;

    UnwindAssemblySP assembly_profiler_sp (GetUnwindAssemblyProfiler(target));
    if (assembly_profiler_sp)
    {
        m_unwind_plan_fast_sp.reset (new 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)
{
    if (m_unwind_plan_arch_default_sp.get() || m_tried_unwind_arch_default)
        return m_unwind_plan_arch_default_sp;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    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.reset (new 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)
{
    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;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    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.reset (new 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)
{
    if (m_first_non_prologue_insn.IsValid())
        return m_first_non_prologue_insn;

    std::lock_guard<std::recursive_mutex> guard(m_mutex);
    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;
    ArchSpec arch;
    if (m_unwind_table.GetArchitecture (arch))
    {
        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, -1);
    if (unwind_plan_sp.get() == nullptr)
    {
        unwind_plan_sp = GetCompactUnwindUnwindPlan (target, -1);
    }
    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, -1);
    if (unwind_plan_sp.get() == nullptr)
    {
        unwind_plan_sp = GetCompactUnwindUnwindPlan (target, -1);
    }
    if (unwind_plan_sp.get() && unwind_plan_sp->GetPersonalityFunctionPtr().IsValid())
    {
        personality_addr = unwind_plan_sp->GetPersonalityFunctionPtr();
    }

    return personality_addr;
}