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llvm / lldb / release_39 / . / source / Plugins / Process / Utility / RegisterContextLLDB.cpp
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//===-- RegisterContextLLDB.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-private.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/AddressRange.h"
#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/RegisterValue.h"
#include "lldb/Core/Value.h"
#include "lldb/Expression/DWARFExpression.h"
#include "lldb/Symbol/ArmUnwindInfo.h"
#include "lldb/Symbol/DWARFCallFrameInfo.h"
#include "lldb/Symbol/FuncUnwinders.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Symbol/SymbolContext.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/DynamicLoader.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Platform.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/SectionLoadList.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "RegisterContextLLDB.h"
using namespace lldb;
using namespace lldb_private;
static ConstString GetSymbolOrFunctionName(const SymbolContext &sym_ctx)
{
if (sym_ctx.symbol)
return sym_ctx.symbol->GetName();
else if (sym_ctx.function)
return sym_ctx.function->GetName();
return ConstString();
}
RegisterContextLLDB::RegisterContextLLDB
(
Thread& thread,
const SharedPtr &next_frame,
SymbolContext& sym_ctx,
uint32_t frame_number,
UnwindLLDB& unwind_lldb
) :
RegisterContext (thread, frame_number),
m_thread(thread),
m_fast_unwind_plan_sp (),
m_full_unwind_plan_sp (),
m_fallback_unwind_plan_sp (),
m_all_registers_available(false),
m_frame_type (-1),
m_cfa (LLDB_INVALID_ADDRESS),
m_start_pc (),
m_current_pc (),
m_current_offset (0),
m_current_offset_backed_up_one (0),
m_sym_ctx(sym_ctx),
m_sym_ctx_valid (false),
m_frame_number (frame_number),
m_registers(),
m_parent_unwind (unwind_lldb)
{
m_sym_ctx.Clear(false);
m_sym_ctx_valid = false;
if (IsFrameZero ())
{
InitializeZerothFrame ();
}
else
{
InitializeNonZerothFrame ();
}
// This same code exists over in the GetFullUnwindPlanForFrame() but it may not have been executed yet
if (IsFrameZero()
|| next_frame->m_frame_type == eTrapHandlerFrame
|| next_frame->m_frame_type == eDebuggerFrame)
{
m_all_registers_available = true;
}
}
bool
RegisterContextLLDB::IsUnwindPlanValidForCurrentPC(lldb::UnwindPlanSP unwind_plan_sp, int &valid_pc_offset)
{
if (!unwind_plan_sp)
return false;
// check if m_current_pc is valid
if (unwind_plan_sp->PlanValidAtAddress(m_current_pc))
{
// yes - current offset can be used as is
valid_pc_offset = m_current_offset;
return true;
}
// if m_current_offset <= 0, we've got nothing else to try
if (m_current_offset <= 0)
return false;
// check pc - 1 to see if it's valid
Address pc_minus_one (m_current_pc);
pc_minus_one.SetOffset(m_current_pc.GetOffset() - 1);
if (unwind_plan_sp->PlanValidAtAddress(pc_minus_one))
{
// *valid_pc_offset = m_current_offset - 1;
valid_pc_offset = m_current_pc.GetOffset() - 1;
return true;
}
return false;
}
// Initialize a RegisterContextLLDB which is the first frame of a stack -- the zeroth frame or currently
// executing frame.
void
RegisterContextLLDB::InitializeZerothFrame()
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
ExecutionContext exe_ctx(m_thread.shared_from_this());
RegisterContextSP reg_ctx_sp = m_thread.GetRegisterContext();
if (reg_ctx_sp.get() == NULL)
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("frame does not have a register context");
return;
}
addr_t current_pc = reg_ctx_sp->GetPC();
if (current_pc == LLDB_INVALID_ADDRESS)
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("frame does not have a pc");
return;
}
Process *process = exe_ctx.GetProcessPtr();
// Let ABIs fixup code addresses to make sure they are valid. In ARM ABIs
// this will strip bit zero in case we read a PC from memory or from the LR.
// (which would be a no-op in frame 0 where we get it from the register set,
// but still a good idea to make the call here for other ABIs that may exist.)
ABI *abi = process->GetABI().get();
if (abi)
current_pc = abi->FixCodeAddress(current_pc);
// Initialize m_current_pc, an Address object, based on current_pc, an addr_t.
m_current_pc.SetLoadAddress (current_pc, &process->GetTarget());
// If we don't have a Module for some reason, we're not going to find symbol/function information - just
// stick in some reasonable defaults and hope we can unwind past this frame.
ModuleSP pc_module_sp (m_current_pc.GetModule());
if (!m_current_pc.IsValid() || !pc_module_sp)
{
UnwindLogMsg ("using architectural default unwind method");
}
// We require either a symbol or function in the symbols context to be successfully
// filled in or this context is of no use to us.
const uint32_t resolve_scope = eSymbolContextFunction | eSymbolContextSymbol;
if (pc_module_sp.get()
&& (pc_module_sp->ResolveSymbolContextForAddress (m_current_pc, resolve_scope, m_sym_ctx) & resolve_scope))
{
m_sym_ctx_valid = true;
}
if (m_sym_ctx.symbol)
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", symbol name is '%s'",
current_pc, GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
}
else if (m_sym_ctx.function)
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", function name is '%s'",
current_pc, GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
}
else
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", no symbol/function name is known.", current_pc);
}
AddressRange addr_range;
m_sym_ctx.GetAddressRange (resolve_scope, 0, false, addr_range);
if (IsTrapHandlerSymbol (process, m_sym_ctx))
{
m_frame_type = eTrapHandlerFrame;
}
else
{
// FIXME: Detect eDebuggerFrame here.
m_frame_type = eNormalFrame;
}
// If we were able to find a symbol/function, set addr_range to the bounds of that symbol/function.
// else treat the current pc value as the start_pc and record no offset.
if (addr_range.GetBaseAddress().IsValid())
{
m_start_pc = addr_range.GetBaseAddress();
if (m_current_pc.GetSection() == m_start_pc.GetSection())
{
m_current_offset = m_current_pc.GetOffset() - m_start_pc.GetOffset();
}
else if (m_current_pc.GetModule() == m_start_pc.GetModule())
{
// This means that whatever symbol we kicked up isn't really correct
// --- we should not cross section boundaries ... We really should NULL out
// the function/symbol in this case unless there is a bad assumption
// here due to inlined functions?
m_current_offset = m_current_pc.GetFileAddress() - m_start_pc.GetFileAddress();
}
m_current_offset_backed_up_one = m_current_offset;
}
else
{
m_start_pc = m_current_pc;
m_current_offset = -1;
m_current_offset_backed_up_one = -1;
}
// We've set m_frame_type and m_sym_ctx before these calls.
m_fast_unwind_plan_sp = GetFastUnwindPlanForFrame ();
m_full_unwind_plan_sp = GetFullUnwindPlanForFrame ();
UnwindPlan::RowSP active_row;
lldb::RegisterKind row_register_kind = eRegisterKindGeneric;
if (m_full_unwind_plan_sp && m_full_unwind_plan_sp->PlanValidAtAddress (m_current_pc))
{
active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
row_register_kind = m_full_unwind_plan_sp->GetRegisterKind ();
if (active_row.get() && log)
{
StreamString active_row_strm;
active_row->Dump(active_row_strm, m_full_unwind_plan_sp.get(), &m_thread, m_start_pc.GetLoadAddress(exe_ctx.GetTargetPtr()));
UnwindLogMsg ("%s", active_row_strm.GetString().c_str());
}
}
if (!active_row.get())
{
UnwindLogMsg ("could not find an unwindplan row for this frame's pc");
m_frame_type = eNotAValidFrame;
return;
}
if (!ReadCFAValueForRow (row_register_kind, active_row, m_cfa))
{
// Try the fall back unwind plan since the
// full unwind plan failed.
FuncUnwindersSP func_unwinders_sp;
UnwindPlanSP call_site_unwind_plan;
bool cfa_status = false;
if (m_sym_ctx_valid)
{
func_unwinders_sp = pc_module_sp->GetObjectFile()->GetUnwindTable().GetFuncUnwindersContainingAddress (m_current_pc, m_sym_ctx);
}
if(func_unwinders_sp.get() != nullptr)
call_site_unwind_plan = func_unwinders_sp->GetUnwindPlanAtCallSite(process->GetTarget(), m_current_offset_backed_up_one);
if (call_site_unwind_plan.get() != nullptr)
{
m_fallback_unwind_plan_sp = call_site_unwind_plan;
if(TryFallbackUnwindPlan())
cfa_status = true;
}
if (!cfa_status)
{
UnwindLogMsg ("could not read CFA value for first frame.");
m_frame_type = eNotAValidFrame;
return;
}
}
UnwindLogMsg ("initialized frame current pc is 0x%" PRIx64 " cfa is 0x%" PRIx64 " using %s UnwindPlan",
(uint64_t) m_current_pc.GetLoadAddress (exe_ctx.GetTargetPtr()),
(uint64_t) m_cfa,
m_full_unwind_plan_sp->GetSourceName().GetCString());
}
// Initialize a RegisterContextLLDB for the non-zeroth frame -- rely on the RegisterContextLLDB "below" it
// to provide things like its current pc value.
void
RegisterContextLLDB::InitializeNonZerothFrame()
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (IsFrameZero ())
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("non-zeroth frame tests positive for IsFrameZero -- that shouldn't happen.");
return;
}
if (!GetNextFrame().get() || !GetNextFrame()->IsValid())
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("Could not get next frame, marking this frame as invalid.");
return;
}
if (!m_thread.GetRegisterContext())
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("Could not get register context for this thread, marking this frame as invalid.");
return;
}
addr_t pc;
if (!ReadGPRValue (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc))
{
UnwindLogMsg ("could not get pc value");
m_frame_type = eNotAValidFrame;
return;
}
if (log)
{
UnwindLogMsg ("pc = 0x%" PRIx64, pc);
addr_t reg_val;
if (ReadGPRValue (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_FP, reg_val))
UnwindLogMsg ("fp = 0x%" PRIx64, reg_val);
if (ReadGPRValue (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP, reg_val))
UnwindLogMsg ("sp = 0x%" PRIx64, reg_val);
}
// A pc of 0x0 means it's the end of the stack crawl unless we're above a trap handler function
bool above_trap_handler = false;
if (GetNextFrame().get() && GetNextFrame()->IsValid() && GetNextFrame()->IsTrapHandlerFrame())
above_trap_handler = true;
if (pc == 0 || pc == 0x1)
{
if (above_trap_handler == false)
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("this frame has a pc of 0x0");
return;
}
}
ExecutionContext exe_ctx(m_thread.shared_from_this());
Process *process = exe_ctx.GetProcessPtr();
// Let ABIs fixup code addresses to make sure they are valid. In ARM ABIs
// this will strip bit zero in case we read a PC from memory or from the LR.
ABI *abi = process->GetABI().get();
if (abi)
pc = abi->FixCodeAddress(pc);
m_current_pc.SetLoadAddress (pc, &process->GetTarget());
// If we don't have a Module for some reason, we're not going to find symbol/function information - just
// stick in some reasonable defaults and hope we can unwind past this frame.
ModuleSP pc_module_sp (m_current_pc.GetModule());
if (!m_current_pc.IsValid() || !pc_module_sp)
{
UnwindLogMsg ("using architectural default unwind method");
// Test the pc value to see if we know it's in an unmapped/non-executable region of memory.
uint32_t permissions;
if (process->GetLoadAddressPermissions(pc, permissions)
&& (permissions & ePermissionsExecutable) == 0)
{
// If this is the second frame off the stack, we may have unwound the first frame
// incorrectly. But using the architecture default unwind plan may get us back on
// track -- albeit possibly skipping a real frame. Give this frame a clearly-invalid
// pc and see if we can get any further.
if (GetNextFrame().get() && GetNextFrame()->IsValid() && GetNextFrame()->IsFrameZero())
{
UnwindLogMsg ("had a pc of 0x%" PRIx64 " which is not in executable memory but on frame 1 -- allowing it once.",
(uint64_t) pc);
m_frame_type = eSkipFrame;
}
else
{
// anywhere other than the second frame, a non-executable pc means we're off in the weeds -- stop now.
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("pc is in a non-executable section of memory and this isn't the 2nd frame in the stack walk.");
return;
}
}
if (abi)
{
m_fast_unwind_plan_sp.reset ();
m_full_unwind_plan_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
abi->CreateDefaultUnwindPlan(*m_full_unwind_plan_sp);
if (m_frame_type != eSkipFrame) // don't override eSkipFrame
{
m_frame_type = eNormalFrame;
}
m_all_registers_available = false;
m_current_offset = -1;
m_current_offset_backed_up_one = -1;
RegisterKind row_register_kind = m_full_unwind_plan_sp->GetRegisterKind ();
UnwindPlan::RowSP row = m_full_unwind_plan_sp->GetRowForFunctionOffset(0);
if (row.get())
{
if (!ReadCFAValueForRow (row_register_kind, row, m_cfa))
{
UnwindLogMsg ("failed to get cfa value");
if (m_frame_type != eSkipFrame) // don't override eSkipFrame
{
m_frame_type = eNotAValidFrame;
}
return;
}
// A couple of sanity checks..
if (m_cfa == LLDB_INVALID_ADDRESS || m_cfa == 0 || m_cfa == 1)
{
UnwindLogMsg ("could not find a valid cfa address");
m_frame_type = eNotAValidFrame;
return;
}
// m_cfa should point into the stack memory; if we can query memory region permissions,
// see if the memory is allocated & readable.
if (process->GetLoadAddressPermissions(m_cfa, permissions)
&& (permissions & ePermissionsReadable) == 0)
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("the CFA points to a region of memory that is not readable");
return;
}
}
else
{
UnwindLogMsg ("could not find a row for function offset zero");
m_frame_type = eNotAValidFrame;
return;
}
if (CheckIfLoopingStack ())
{
TryFallbackUnwindPlan();
if (CheckIfLoopingStack ())
{
UnwindLogMsg ("same CFA address as next frame, assuming the unwind is looping - stopping");
m_frame_type = eNotAValidFrame;
return;
}
}
UnwindLogMsg ("initialized frame cfa is 0x%" PRIx64, (uint64_t) m_cfa);
return;
}
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("could not find any symbol for this pc, or a default unwind plan, to continue unwind.");
return;
}
bool resolve_tail_call_address = false; // m_current_pc can be one past the address range of the function...
// If the saved pc does not point to a function/symbol because it is
// beyond the bounds of the correct function and there's no symbol there,
// we do *not* want ResolveSymbolContextForAddress to back up the pc by 1,
// because then we might not find the correct unwind information later.
// Instead, let ResolveSymbolContextForAddress fail, and handle the case
// via decr_pc_and_recompute_addr_range below.
const uint32_t resolve_scope = eSymbolContextFunction | eSymbolContextSymbol;
uint32_t resolved_scope = pc_module_sp->ResolveSymbolContextForAddress (m_current_pc,
resolve_scope,
m_sym_ctx, resolve_tail_call_address);
// We require either a symbol or function in the symbols context to be successfully
// filled in or this context is of no use to us.
if (resolve_scope & resolved_scope)
{
m_sym_ctx_valid = true;
}
if (m_sym_ctx.symbol)
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", symbol name is '%s'",
pc, GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
}
else if (m_sym_ctx.function)
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", function name is '%s'",
pc, GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
}
else
{
UnwindLogMsg ("with pc value of 0x%" PRIx64 ", no symbol/function name is known.", pc);
}
AddressRange addr_range;
if (!m_sym_ctx.GetAddressRange (resolve_scope, 0, false, addr_range))
{
m_sym_ctx_valid = false;
}
bool decr_pc_and_recompute_addr_range = false;
// If the symbol lookup failed...
if (m_sym_ctx_valid == false)
decr_pc_and_recompute_addr_range = true;
// Or if we're in the middle of the stack (and not "above" an asynchronous event like sigtramp),
// and our "current" pc is the start of a function...
if (m_sym_ctx_valid
&& GetNextFrame()->m_frame_type != eTrapHandlerFrame
&& GetNextFrame()->m_frame_type != eDebuggerFrame
&& addr_range.GetBaseAddress().IsValid()
&& addr_range.GetBaseAddress().GetSection() == m_current_pc.GetSection()
&& addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset())
{
decr_pc_and_recompute_addr_range = true;
}
// We need to back up the pc by 1 byte and re-search for the Symbol to handle the case where the "saved pc"
// value is pointing to the next function, e.g. if a function ends with a CALL instruction.
// FIXME this may need to be an architectural-dependent behavior; if so we'll need to add a member function
// to the ABI plugin and consult that.
if (decr_pc_and_recompute_addr_range)
{
UnwindLogMsg ("Backing up the pc value of 0x%" PRIx64 " by 1 and re-doing symbol lookup; old symbol was %s",
pc, GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
Address temporary_pc;
temporary_pc.SetLoadAddress (pc - 1, &process->GetTarget());
m_sym_ctx.Clear (false);
m_sym_ctx_valid = false;
uint32_t resolve_scope = eSymbolContextFunction | eSymbolContextSymbol;
ModuleSP temporary_module_sp = temporary_pc.GetModule();
if (temporary_module_sp &&
temporary_module_sp->ResolveSymbolContextForAddress (temporary_pc, resolve_scope, m_sym_ctx) & resolve_scope)
{
if (m_sym_ctx.GetAddressRange (resolve_scope, 0, false, addr_range))
m_sym_ctx_valid = true;
}
UnwindLogMsg ("Symbol is now %s", GetSymbolOrFunctionName(m_sym_ctx).AsCString(""));
}
// If we were able to find a symbol/function, set addr_range_ptr to the bounds of that symbol/function.
// else treat the current pc value as the start_pc and record no offset.
if (addr_range.GetBaseAddress().IsValid())
{
m_start_pc = addr_range.GetBaseAddress();
m_current_offset = pc - m_start_pc.GetLoadAddress (&process->GetTarget());
m_current_offset_backed_up_one = m_current_offset;
if (decr_pc_and_recompute_addr_range && m_current_offset_backed_up_one > 0)
{
m_current_offset_backed_up_one--;
if (m_sym_ctx_valid)
{
m_current_pc.SetLoadAddress (pc - 1, &process->GetTarget());
}
}
}
else
{
m_start_pc = m_current_pc;
m_current_offset = -1;
m_current_offset_backed_up_one = -1;
}
if (IsTrapHandlerSymbol (process, m_sym_ctx))
{
m_frame_type = eTrapHandlerFrame;
}
else
{
// FIXME: Detect eDebuggerFrame here.
if (m_frame_type != eSkipFrame) // don't override eSkipFrame
{
m_frame_type = eNormalFrame;
}
}
// We've set m_frame_type and m_sym_ctx before this call.
m_fast_unwind_plan_sp = GetFastUnwindPlanForFrame ();
UnwindPlan::RowSP active_row;
RegisterKind row_register_kind = eRegisterKindGeneric;
// Try to get by with just the fast UnwindPlan if possible - the full UnwindPlan may be expensive to get
// (e.g. if we have to parse the entire eh_frame section of an ObjectFile for the first time.)
if (m_fast_unwind_plan_sp && m_fast_unwind_plan_sp->PlanValidAtAddress (m_current_pc))
{
active_row = m_fast_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
row_register_kind = m_fast_unwind_plan_sp->GetRegisterKind ();
if (active_row.get() && log)
{
StreamString active_row_strm;
active_row->Dump(active_row_strm, m_fast_unwind_plan_sp.get(), &m_thread, m_start_pc.GetLoadAddress(exe_ctx.GetTargetPtr()));
UnwindLogMsg ("active row: %s", active_row_strm.GetString().c_str());
}
}
else
{
m_full_unwind_plan_sp = GetFullUnwindPlanForFrame ();
int valid_offset = -1;
if (IsUnwindPlanValidForCurrentPC(m_full_unwind_plan_sp, valid_offset))
{
active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (valid_offset);
row_register_kind = m_full_unwind_plan_sp->GetRegisterKind ();
if (active_row.get() && log)
{
StreamString active_row_strm;
active_row->Dump(active_row_strm, m_full_unwind_plan_sp.get(), &m_thread, m_start_pc.GetLoadAddress(exe_ctx.GetTargetPtr()));
UnwindLogMsg ("active row: %s", active_row_strm.GetString().c_str());
}
}
}
if (!active_row.get())
{
m_frame_type = eNotAValidFrame;
UnwindLogMsg ("could not find unwind row for this pc");
return;
}
if (!ReadCFAValueForRow (row_register_kind, active_row, m_cfa))
{
UnwindLogMsg ("failed to get cfa");
m_frame_type = eNotAValidFrame;
return;
}
UnwindLogMsg ("m_cfa = 0x%" PRIx64, m_cfa);
if (CheckIfLoopingStack ())
{
TryFallbackUnwindPlan();
if (CheckIfLoopingStack ())
{
UnwindLogMsg ("same CFA address as next frame, assuming the unwind is looping - stopping");
m_frame_type = eNotAValidFrame;
return;
}
}
UnwindLogMsg ("initialized frame current pc is 0x%" PRIx64 " cfa is 0x%" PRIx64,
(uint64_t) m_current_pc.GetLoadAddress (exe_ctx.GetTargetPtr()), (uint64_t) m_cfa);
}
bool
RegisterContextLLDB::CheckIfLoopingStack ()
{
// If we have a bad stack setup, we can get the same CFA value multiple times -- or even
// more devious, we can actually oscillate between two CFA values. Detect that here and
// break out to avoid a possible infinite loop in lldb trying to unwind the stack.
// To detect when we have the same CFA value multiple times, we compare the CFA of the current
// frame with the 2nd next frame because in some specail case (e.g. signal hanlders, hand
// written assembly without ABI compiance) we can have 2 frames with the same CFA (in theory we
// can have arbitrary number of frames with the same CFA, but more then 2 is very very unlikely)
RegisterContextLLDB::SharedPtr next_frame = GetNextFrame();
if (next_frame)
{
RegisterContextLLDB::SharedPtr next_next_frame = next_frame->GetNextFrame();
addr_t next_next_frame_cfa = LLDB_INVALID_ADDRESS;
if (next_next_frame && next_next_frame->GetCFA(next_next_frame_cfa))
{
if (next_next_frame_cfa == m_cfa)
{
// We have a loop in the stack unwind
return true;
}
}
}
return false;
}
bool
RegisterContextLLDB::IsFrameZero () const
{
return m_frame_number == 0;
}
// Find a fast unwind plan for this frame, if possible.
//
// On entry to this method,
//
// 1. m_frame_type should already be set to eTrapHandlerFrame/eDebuggerFrame if either of those are correct,
// 2. m_sym_ctx should already be filled in, and
// 3. m_current_pc should have the current pc value for this frame
// 4. m_current_offset_backed_up_one should have the current byte offset into the function, maybe backed up by 1, -1 if unknown
UnwindPlanSP
RegisterContextLLDB::GetFastUnwindPlanForFrame ()
{
UnwindPlanSP unwind_plan_sp;
ModuleSP pc_module_sp (m_current_pc.GetModule());
if (!m_current_pc.IsValid() || !pc_module_sp || pc_module_sp->GetObjectFile() == NULL)
return unwind_plan_sp;
if (IsFrameZero ())
return unwind_plan_sp;
FuncUnwindersSP func_unwinders_sp (pc_module_sp->GetObjectFile()->GetUnwindTable().GetFuncUnwindersContainingAddress (m_current_pc, m_sym_ctx));
if (!func_unwinders_sp)
return unwind_plan_sp;
// If we're in _sigtramp(), unwinding past this frame requires special knowledge.
if (m_frame_type == eTrapHandlerFrame || m_frame_type == eDebuggerFrame)
return unwind_plan_sp;
unwind_plan_sp = func_unwinders_sp->GetUnwindPlanFastUnwind (*m_thread.CalculateTarget(), m_thread);
if (unwind_plan_sp)
{
if (unwind_plan_sp->PlanValidAtAddress (m_current_pc))
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log && log->GetVerbose())
{
if (m_fast_unwind_plan_sp)
UnwindLogMsgVerbose ("frame, and has a fast UnwindPlan");
else
UnwindLogMsgVerbose ("frame");
}
m_frame_type = eNormalFrame;
return unwind_plan_sp;
}
else
{
unwind_plan_sp.reset();
}
}
return unwind_plan_sp;
}
// On entry to this method,
//
// 1. m_frame_type should already be set to eTrapHandlerFrame/eDebuggerFrame if either of those are correct,
// 2. m_sym_ctx should already be filled in, and
// 3. m_current_pc should have the current pc value for this frame
// 4. m_current_offset_backed_up_one should have the current byte offset into the function, maybe backed up by 1, -1 if unknown
UnwindPlanSP
RegisterContextLLDB::GetFullUnwindPlanForFrame ()
{
UnwindPlanSP unwind_plan_sp;
UnwindPlanSP arch_default_unwind_plan_sp;
ExecutionContext exe_ctx(m_thread.shared_from_this());
Process *process = exe_ctx.GetProcessPtr();
ABI *abi = process ? process->GetABI().get() : NULL;
if (abi)
{
arch_default_unwind_plan_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
abi->CreateDefaultUnwindPlan(*arch_default_unwind_plan_sp);
}
else
{
UnwindLogMsg ("unable to get architectural default UnwindPlan from ABI plugin");
}
bool behaves_like_zeroth_frame = false;
if (IsFrameZero ()
|| GetNextFrame()->m_frame_type == eTrapHandlerFrame
|| GetNextFrame()->m_frame_type == eDebuggerFrame)
{
behaves_like_zeroth_frame = true;
// If this frame behaves like a 0th frame (currently executing or
// interrupted asynchronously), all registers can be retrieved.
m_all_registers_available = true;
}
// If we've done a jmp 0x0 / bl 0x0 (called through a null function pointer) so the pc is 0x0
// in the zeroth frame, we need to use the "unwind at first instruction" arch default UnwindPlan
// Also, if this Process can report on memory region attributes, any non-executable region means
// we jumped through a bad function pointer - handle the same way as 0x0.
// Note, if we have a symbol context & a symbol, we don't want to follow this code path. This is
// for jumping to memory regions without any information available.
if ((!m_sym_ctx_valid || (m_sym_ctx.function == NULL && m_sym_ctx.symbol == NULL)) && behaves_like_zeroth_frame && m_current_pc.IsValid())
{
uint32_t permissions;
addr_t current_pc_addr = m_current_pc.GetLoadAddress (exe_ctx.GetTargetPtr());
if (current_pc_addr == 0
|| (process &&
process->GetLoadAddressPermissions (current_pc_addr, permissions)
&& (permissions & ePermissionsExecutable) == 0))
{
if (abi)
{
unwind_plan_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
abi->CreateFunctionEntryUnwindPlan(*unwind_plan_sp);
m_frame_type = eNormalFrame;
return unwind_plan_sp;
}
}
}
// No Module for the current pc, try using the architecture default unwind.
ModuleSP pc_module_sp (m_current_pc.GetModule());
if (!m_current_pc.IsValid() || !pc_module_sp || pc_module_sp->GetObjectFile() == NULL)
{
m_frame_type = eNormalFrame;
return arch_default_unwind_plan_sp;
}
FuncUnwindersSP func_unwinders_sp;
if (m_sym_ctx_valid)
{
func_unwinders_sp = pc_module_sp->GetObjectFile()->GetUnwindTable().GetFuncUnwindersContainingAddress (m_current_pc, m_sym_ctx);
}
// No FuncUnwinders available for this pc (stripped function symbols, lldb could not augment its
// function table with another source, like LC_FUNCTION_STARTS or eh_frame in ObjectFileMachO).
// See if eh_frame or the .ARM.exidx tables have unwind information for this address, else fall
// back to the architectural default unwind.
if (!func_unwinders_sp)
{
m_frame_type = eNormalFrame;
if (!pc_module_sp || !pc_module_sp->GetObjectFile() || !m_current_pc.IsValid())
return arch_default_unwind_plan_sp;
// Even with -fomit-frame-pointer, we can try eh_frame to get back on track.
DWARFCallFrameInfo *eh_frame = pc_module_sp->GetObjectFile()->GetUnwindTable().GetEHFrameInfo();
if (eh_frame)
{
unwind_plan_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
if (eh_frame->GetUnwindPlan (m_current_pc, *unwind_plan_sp))
return unwind_plan_sp;
else
unwind_plan_sp.reset();
}
ArmUnwindInfo *arm_exidx = pc_module_sp->GetObjectFile()->GetUnwindTable().GetArmUnwindInfo();
if (arm_exidx)
{
unwind_plan_sp.reset (new UnwindPlan (lldb::eRegisterKindGeneric));
if (arm_exidx->GetUnwindPlan (exe_ctx.GetTargetRef(), m_current_pc, *unwind_plan_sp))
return unwind_plan_sp;
else
unwind_plan_sp.reset();
}
return arch_default_unwind_plan_sp;
}
// If we're in _sigtramp(), unwinding past this frame requires special knowledge. On Mac OS X this knowledge
// is properly encoded in the eh_frame section, so prefer that if available.
// On other platforms we may need to provide a platform-specific UnwindPlan which encodes the details of
// how to unwind out of sigtramp.
if (m_frame_type == eTrapHandlerFrame && process)
{
m_fast_unwind_plan_sp.reset();
unwind_plan_sp = func_unwinders_sp->GetEHFrameUnwindPlan (process->GetTarget(), m_current_offset_backed_up_one);
if (unwind_plan_sp && unwind_plan_sp->PlanValidAtAddress (m_current_pc) && unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolYes)
{
return unwind_plan_sp;
}
}
// Ask the DynamicLoader if the eh_frame CFI should be trusted in this frame even when it's frame zero
// This comes up if we have hand-written functions in a Module and hand-written eh_frame. The assembly
// instruction inspection may fail and the eh_frame CFI were probably written with some care to do the
// right thing. It'd be nice if there was a way to ask the eh_frame directly if it is asynchronous
// (can be trusted at every instruction point) or synchronous (the normal case - only at call sites).
// But there is not.
if (process && process->GetDynamicLoader() && process->GetDynamicLoader()->AlwaysRelyOnEHUnwindInfo (m_sym_ctx))
{
// We must specifically call the GetEHFrameUnwindPlan() method here -- normally we would
// call GetUnwindPlanAtCallSite() -- because CallSite may return an unwind plan sourced from
// either eh_frame (that's what we intend) or compact unwind (this won't work)
unwind_plan_sp = func_unwinders_sp->GetEHFrameUnwindPlan (process->GetTarget(), m_current_offset_backed_up_one);
if (unwind_plan_sp && unwind_plan_sp->PlanValidAtAddress (m_current_pc))
{
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan because the DynamicLoader suggested we prefer it",
unwind_plan_sp->GetSourceName().GetCString());
return unwind_plan_sp;
}
}
// Typically the NonCallSite UnwindPlan is the unwind created by inspecting the assembly language instructions
if (behaves_like_zeroth_frame && process)
{
unwind_plan_sp = func_unwinders_sp->GetUnwindPlanAtNonCallSite (process->GetTarget(), m_thread, m_current_offset_backed_up_one);
if (unwind_plan_sp && unwind_plan_sp->PlanValidAtAddress (m_current_pc))
{
if (unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolNo)
{
// We probably have an UnwindPlan created by inspecting assembly instructions. The
// assembly profilers work really well with compiler-generated functions but hand-
// written assembly can be problematic. We set the eh_frame based unwind plan as our
// fallback unwind plan if instruction emulation doesn't work out even for non call
// sites if it is available and use the architecture default unwind plan if it is
// not available. The eh_frame unwind plan is more reliable even on non call sites
// then the architecture default plan and for hand written assembly code it is often
// written in a way that it valid at all location what helps in the most common
// cases when the instruction emulation fails.
UnwindPlanSP call_site_unwind_plan = func_unwinders_sp->GetUnwindPlanAtCallSite(process->GetTarget(), m_current_offset_backed_up_one);
if (call_site_unwind_plan &&
call_site_unwind_plan.get() != unwind_plan_sp.get() &&
call_site_unwind_plan->GetSourceName() != unwind_plan_sp->GetSourceName())
{
m_fallback_unwind_plan_sp = call_site_unwind_plan;
}
else
{
m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp;
}
}
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", unwind_plan_sp->GetSourceName().GetCString());
return unwind_plan_sp;
}
}
// Typically this is unwind info from an eh_frame section intended for exception handling; only valid at call sites
if (process)
{
unwind_plan_sp = func_unwinders_sp->GetUnwindPlanAtCallSite (process->GetTarget(), m_current_offset_backed_up_one);
}
int valid_offset = -1;
if (IsUnwindPlanValidForCurrentPC(unwind_plan_sp, valid_offset))
{
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", unwind_plan_sp->GetSourceName().GetCString());
return unwind_plan_sp;
}
// We'd prefer to use an UnwindPlan intended for call sites when we're at a call site but if we've
// struck out on that, fall back to using the non-call-site assembly inspection UnwindPlan if possible.
if (process)
{
unwind_plan_sp = func_unwinders_sp->GetUnwindPlanAtNonCallSite (process->GetTarget(), m_thread, m_current_offset_backed_up_one);
}
if (unwind_plan_sp && unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolNo)
{
// We probably have an UnwindPlan created by inspecting assembly instructions. The assembly
// profilers work really well with compiler-generated functions but hand- written assembly
// can be problematic. We set the eh_frame based unwind plan as our fallback unwind plan if
// instruction emulation doesn't work out even for non call sites if it is available and use
// the architecture default unwind plan if it is not available. The eh_frame unwind plan is
// more reliable even on non call sites then the architecture default plan and for hand
// written assembly code it is often written in a way that it valid at all location what
// helps in the most common cases when the instruction emulation fails.
UnwindPlanSP call_site_unwind_plan = func_unwinders_sp->GetUnwindPlanAtCallSite(process->GetTarget(), m_current_offset_backed_up_one);
if (call_site_unwind_plan &&
call_site_unwind_plan.get() != unwind_plan_sp.get() &&
call_site_unwind_plan->GetSourceName() != unwind_plan_sp->GetSourceName())
{
m_fallback_unwind_plan_sp = call_site_unwind_plan;
}
else
{
m_fallback_unwind_plan_sp = arch_default_unwind_plan_sp;
}
}
if (IsUnwindPlanValidForCurrentPC(unwind_plan_sp, valid_offset))
{
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", unwind_plan_sp->GetSourceName().GetCString());
return unwind_plan_sp;
}
// If we're on the first instruction of a function, and we have an architectural default UnwindPlan
// for the initial instruction of a function, use that.
if (m_current_offset_backed_up_one == 0)
{
unwind_plan_sp = func_unwinders_sp->GetUnwindPlanArchitectureDefaultAtFunctionEntry (m_thread);
if (unwind_plan_sp)
{
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", unwind_plan_sp->GetSourceName().GetCString());
return unwind_plan_sp;
}
}
// If nothing else, use the architectural default UnwindPlan and hope that does the job.
if (arch_default_unwind_plan_sp)
UnwindLogMsgVerbose ("frame uses %s for full UnwindPlan", arch_default_unwind_plan_sp->GetSourceName().GetCString());
else
UnwindLogMsg ("Unable to find any UnwindPlan for full unwind of this frame.");
return arch_default_unwind_plan_sp;
}
void
RegisterContextLLDB::InvalidateAllRegisters ()
{
m_frame_type = eNotAValidFrame;
}
size_t
RegisterContextLLDB::GetRegisterCount ()
{
return m_thread.GetRegisterContext()->GetRegisterCount();
}
const RegisterInfo *
RegisterContextLLDB::GetRegisterInfoAtIndex (size_t reg)
{
return m_thread.GetRegisterContext()->GetRegisterInfoAtIndex (reg);
}
size_t
RegisterContextLLDB::GetRegisterSetCount ()
{
return m_thread.GetRegisterContext()->GetRegisterSetCount ();
}
const RegisterSet *
RegisterContextLLDB::GetRegisterSet (size_t reg_set)
{
return m_thread.GetRegisterContext()->GetRegisterSet (reg_set);
}
uint32_t
RegisterContextLLDB::ConvertRegisterKindToRegisterNumber (lldb::RegisterKind kind, uint32_t num)
{
return m_thread.GetRegisterContext()->ConvertRegisterKindToRegisterNumber (kind, num);
}
bool
RegisterContextLLDB::ReadRegisterValueFromRegisterLocation (lldb_private::UnwindLLDB::RegisterLocation regloc,
const RegisterInfo *reg_info,
RegisterValue &value)
{
if (!IsValid())
return false;
bool success = false;
switch (regloc.type)
{
case UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
if (!other_reg_info)
return false;
success = m_thread.GetRegisterContext()->ReadRegister (other_reg_info, value);
}
break;
case UnwindLLDB::RegisterLocation::eRegisterInRegister:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
if (!other_reg_info)
return false;
if (IsFrameZero ())
{
success = m_thread.GetRegisterContext()->ReadRegister (other_reg_info, value);
}
else
{
success = GetNextFrame()->ReadRegister (other_reg_info, value);
}
}
break;
case UnwindLLDB::RegisterLocation::eRegisterValueInferred:
success = value.SetUInt (regloc.location.inferred_value, reg_info->byte_size);
break;
case UnwindLLDB::RegisterLocation::eRegisterNotSaved:
break;
case UnwindLLDB::RegisterLocation::eRegisterSavedAtHostMemoryLocation:
assert ("FIXME debugger inferior function call unwind");
break;
case UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation:
{
Error error (ReadRegisterValueFromMemory(reg_info,
regloc.location.target_memory_location,
reg_info->byte_size,
value));
success = error.Success();
}
break;
default:
assert ("Unknown RegisterLocation type.");
break;
}
return success;
}
bool
RegisterContextLLDB::WriteRegisterValueToRegisterLocation (lldb_private::UnwindLLDB::RegisterLocation regloc,
const RegisterInfo *reg_info,
const RegisterValue &value)
{
if (!IsValid())
return false;
bool success = false;
switch (regloc.type)
{
case UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
success = m_thread.GetRegisterContext()->WriteRegister (other_reg_info, value);
}
break;
case UnwindLLDB::RegisterLocation::eRegisterInRegister:
{
const RegisterInfo *other_reg_info = GetRegisterInfoAtIndex(regloc.location.register_number);
if (IsFrameZero ())
{
success = m_thread.GetRegisterContext()->WriteRegister (other_reg_info, value);
}
else
{
success = GetNextFrame()->WriteRegister (other_reg_info, value);
}
}
break;
case UnwindLLDB::RegisterLocation::eRegisterValueInferred:
case UnwindLLDB::RegisterLocation::eRegisterNotSaved:
break;
case UnwindLLDB::RegisterLocation::eRegisterSavedAtHostMemoryLocation:
assert ("FIXME debugger inferior function call unwind");
break;
case UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation:
{
Error error (WriteRegisterValueToMemory (reg_info,
regloc.location.target_memory_location,
reg_info->byte_size,
value));
success = error.Success();
}
break;
default:
assert ("Unknown RegisterLocation type.");
break;
}
return success;
}
bool
RegisterContextLLDB::IsValid () const
{
return m_frame_type != eNotAValidFrame;
}
// After the final stack frame in a stack walk we'll get one invalid (eNotAValidFrame) stack frame --
// one past the end of the stack walk. But higher-level code will need to tell the differnece between
// "the unwind plan below this frame failed" versus "we successfully completed the stack walk" so
// this method helps to disambiguate that.
bool
RegisterContextLLDB::IsTrapHandlerFrame () const
{
return m_frame_type == eTrapHandlerFrame;
}
// A skip frame is a bogus frame on the stack -- but one where we're likely to find a real frame farther
// up the stack if we keep looking. It's always the second frame in an unwind (i.e. the first frame after
// frame zero) where unwinding can be the trickiest. Ideally we'll mark up this frame in some way so the
// user knows we're displaying bad data and we may have skipped one frame of their real program in the
// process of getting back on track.
bool
RegisterContextLLDB::IsSkipFrame () const
{
return m_frame_type == eSkipFrame;
}
bool
RegisterContextLLDB::IsTrapHandlerSymbol (lldb_private::Process *process, const lldb_private::SymbolContext &m_sym_ctx) const
{
PlatformSP platform_sp (process->GetTarget().GetPlatform());
if (platform_sp)
{
const std::vector<ConstString> trap_handler_names (platform_sp->GetTrapHandlerSymbolNames());
for (ConstString name : trap_handler_names)
{
if ((m_sym_ctx.function && m_sym_ctx.function->GetName() == name) ||
(m_sym_ctx.symbol && m_sym_ctx.symbol->GetName() == name))
{
return true;
}
}
}
const std::vector<ConstString> user_specified_trap_handler_names (m_parent_unwind.GetUserSpecifiedTrapHandlerFunctionNames());
for (ConstString name : user_specified_trap_handler_names)
{
if ((m_sym_ctx.function && m_sym_ctx.function->GetName() == name) ||
(m_sym_ctx.symbol && m_sym_ctx.symbol->GetName() == name))
{
return true;
}
}
return false;
}
// Answer the question: Where did THIS frame save the CALLER frame ("previous" frame)'s register value?
enum UnwindLLDB::RegisterSearchResult
RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc)
{
RegisterNumber regnum (m_thread, eRegisterKindLLDB, lldb_regnum);
// Have we already found this register location?
if (!m_registers.empty())
{
std::map<uint32_t, lldb_private::UnwindLLDB::RegisterLocation>::const_iterator iterator;
iterator = m_registers.find (regnum.GetAsKind (eRegisterKindLLDB));
if (iterator != m_registers.end())
{
regloc = iterator->second;
UnwindLogMsg ("supplying caller's saved %s (%d)'s location, cached",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
// Look through the available UnwindPlans for the register location.
UnwindPlan::Row::RegisterLocation unwindplan_regloc;
bool have_unwindplan_regloc = false;
RegisterKind unwindplan_registerkind = kNumRegisterKinds;
if (m_fast_unwind_plan_sp)
{
UnwindPlan::RowSP active_row = m_fast_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
unwindplan_registerkind = m_fast_unwind_plan_sp->GetRegisterKind ();
if (regnum.GetAsKind (unwindplan_registerkind) == LLDB_INVALID_REGNUM)
{
UnwindLogMsg ("could not convert lldb regnum %s (%d) into %d RegisterKind reg numbering scheme",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB), (int) unwindplan_registerkind);
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
if (active_row->GetRegisterInfo (regnum.GetAsKind (unwindplan_registerkind), unwindplan_regloc))
{
UnwindLogMsg ("supplying caller's saved %s (%d)'s location using FastUnwindPlan",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
have_unwindplan_regloc = true;
}
}
if (!have_unwindplan_regloc)
{
// m_full_unwind_plan_sp being NULL means that we haven't tried to find a full UnwindPlan yet
if (!m_full_unwind_plan_sp)
m_full_unwind_plan_sp = GetFullUnwindPlanForFrame ();
if (m_full_unwind_plan_sp)
{
RegisterNumber pc_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
UnwindPlan::RowSP active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
unwindplan_registerkind = m_full_unwind_plan_sp->GetRegisterKind ();
RegisterNumber return_address_reg;
// If we're fetching the saved pc and this UnwindPlan defines a ReturnAddress register (e.g. lr on arm),
// look for the return address register number in the UnwindPlan's row.
if (pc_regnum.IsValid()
&& pc_regnum == regnum
&& m_full_unwind_plan_sp->GetReturnAddressRegister() != LLDB_INVALID_REGNUM)
{
return_address_reg.init (m_thread, m_full_unwind_plan_sp->GetRegisterKind(), m_full_unwind_plan_sp->GetReturnAddressRegister());
regnum = return_address_reg;
UnwindLogMsg ("requested caller's saved PC but this UnwindPlan uses a RA reg; getting %s (%d) instead",
return_address_reg.GetName(), return_address_reg.GetAsKind (eRegisterKindLLDB));
}
else
{
if (regnum.GetAsKind (unwindplan_registerkind) == LLDB_INVALID_REGNUM)
{
if (unwindplan_registerkind == eRegisterKindGeneric)
{
UnwindLogMsg ("could not convert lldb regnum %s (%d) into eRegisterKindGeneric reg numbering scheme",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
}
else
{
UnwindLogMsg ("could not convert lldb regnum %s (%d) into %d RegisterKind reg numbering scheme",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB), (int) unwindplan_registerkind);
}
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
}
if (regnum.IsValid()
&& active_row->GetRegisterInfo (regnum.GetAsKind (unwindplan_registerkind), unwindplan_regloc))
{
have_unwindplan_regloc = true;
UnwindLogMsg ("supplying caller's saved %s (%d)'s location using %s UnwindPlan",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
m_full_unwind_plan_sp->GetSourceName().GetCString());
}
// This is frame 0 and we're retrieving the PC and it's saved in a Return Address register and
// it hasn't been saved anywhere yet -- that is, it's still live in the actual register.
// Handle this specially.
if (have_unwindplan_regloc == false
&& return_address_reg.IsValid()
&& IsFrameZero())
{
if (return_address_reg.GetAsKind (eRegisterKindLLDB) != LLDB_INVALID_REGNUM)
{
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext;
new_regloc.location.register_number = return_address_reg.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
regloc = new_regloc;
UnwindLogMsg ("supplying caller's register %s (%d) from the live RegisterContext at frame 0, saved in %d",
return_address_reg.GetName(), return_address_reg.GetAsKind (eRegisterKindLLDB),
return_address_reg.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
// If this architecture stores the return address in a register (it defines a Return Address register)
// and we're on a non-zero stack frame and the Full UnwindPlan says that the pc is stored in the
// RA registers (e.g. lr on arm), then we know that the full unwindplan is not trustworthy -- this
// is an impossible situation and the instruction emulation code has likely been misled.
// If this stack frame meets those criteria, we need to throw away the Full UnwindPlan that the
// instruction emulation came up with and fall back to the architecture's Default UnwindPlan so
// the stack walk can get past this point.
// Special note: If the Full UnwindPlan was generated from the compiler, don't second-guess it
// when we're at a call site location.
// arch_default_ra_regnum is the return address register # in the Full UnwindPlan register numbering
RegisterNumber arch_default_ra_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA);
if (arch_default_ra_regnum.GetAsKind (unwindplan_registerkind) != LLDB_INVALID_REGNUM
&& pc_regnum == regnum
&& unwindplan_regloc.IsInOtherRegister()
&& unwindplan_regloc.GetRegisterNumber() == arch_default_ra_regnum.GetAsKind (unwindplan_registerkind)
&& m_full_unwind_plan_sp->GetSourcedFromCompiler() != eLazyBoolYes
&& !m_all_registers_available)
{
UnwindLogMsg ("%s UnwindPlan tried to restore the pc from the link register but this is a non-zero frame",
m_full_unwind_plan_sp->GetSourceName().GetCString());
// Throw away the full unwindplan; install the arch default unwindplan
if (ForceSwitchToFallbackUnwindPlan())
{
// Update for the possibly new unwind plan
unwindplan_registerkind = m_full_unwind_plan_sp->GetRegisterKind ();
UnwindPlan::RowSP active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
// Sanity check: Verify that we can fetch a pc value and CFA value with this unwind plan
RegisterNumber arch_default_pc_reg (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
bool can_fetch_pc_value = false;
bool can_fetch_cfa = false;
addr_t cfa_value;
if (active_row)
{
if (arch_default_pc_reg.GetAsKind (unwindplan_registerkind) != LLDB_INVALID_REGNUM
&& active_row->GetRegisterInfo (arch_default_pc_reg.GetAsKind (unwindplan_registerkind), unwindplan_regloc))
{
can_fetch_pc_value = true;
}
if (ReadCFAValueForRow (unwindplan_registerkind, active_row, cfa_value))
{
can_fetch_cfa = true;
}
}
if (can_fetch_pc_value && can_fetch_cfa)
{
have_unwindplan_regloc = true;
}
else
{
have_unwindplan_regloc = false;
}
}
else
{
// We were unable to fall back to another unwind plan
have_unwindplan_regloc = false;
}
}
}
}
ExecutionContext exe_ctx(m_thread.shared_from_this());
Process *process = exe_ctx.GetProcessPtr();
if (have_unwindplan_regloc == false)
{
// If the UnwindPlan failed to give us an unwind location for this register, we may be able to fall back
// to some ABI-defined default. For example, some ABIs allow to determine the caller's SP via the CFA.
// Also, the ABI may set volatile registers to the undefined state.
ABI *abi = process ? process->GetABI().get() : NULL;
if (abi)
{
const RegisterInfo *reg_info = GetRegisterInfoAtIndex(regnum.GetAsKind (eRegisterKindLLDB));
if (reg_info && abi->GetFallbackRegisterLocation (reg_info, unwindplan_regloc))
{
UnwindLogMsg ("supplying caller's saved %s (%d)'s location using ABI default",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
have_unwindplan_regloc = true;
}
}
}
if (have_unwindplan_regloc == false)
{
if (IsFrameZero ())
{
// This is frame 0 - we should return the actual live register context value
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext;
new_regloc.location.register_number = regnum.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
regloc = new_regloc;
UnwindLogMsg ("supplying caller's register %s (%d) from the live RegisterContext at frame 0",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
else
{
std::string unwindplan_name ("");
if (m_full_unwind_plan_sp)
{
unwindplan_name += "via '";
unwindplan_name += m_full_unwind_plan_sp->GetSourceName().AsCString();
unwindplan_name += "'";
}
UnwindLogMsg ("no save location for %s (%d) %s",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
unwindplan_name.c_str());
}
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
// unwindplan_regloc has valid contents about where to retrieve the register
if (unwindplan_regloc.IsUnspecified())
{
lldb_private::UnwindLLDB::RegisterLocation new_regloc;
new_regloc.type = UnwindLLDB::RegisterLocation::eRegisterNotSaved;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = new_regloc;
UnwindLogMsg ("save location for %s (%d) is unspecified, continue searching",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
if (unwindplan_regloc.IsUndefined())
{
UnwindLogMsg ("did not supply reg location for %s (%d) because it is volatile",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterIsVolatile;
}
if (unwindplan_regloc.IsSame())
{
if (IsFrameZero() == false
&& (regnum.GetAsKind (eRegisterKindGeneric) == LLDB_REGNUM_GENERIC_PC
|| regnum.GetAsKind (eRegisterKindGeneric) == LLDB_REGNUM_GENERIC_RA))
{
UnwindLogMsg ("register %s (%d) is marked as 'IsSame' - it is a pc or return address reg on a non-zero frame -- treat as if we have no information",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
else
{
regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
regloc.location.register_number = regnum.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d), saved in register %s (%d)",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
if (unwindplan_regloc.IsCFAPlusOffset())
{
int offset = unwindplan_regloc.GetOffset();
regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
regloc.location.inferred_value = m_cfa + offset;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d), value is CFA plus offset %d [value is 0x%" PRIx64 "]",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
offset, regloc.location.inferred_value);
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsAtCFAPlusOffset())
{
int offset = unwindplan_regloc.GetOffset();
regloc.type = UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation;
regloc.location.target_memory_location = m_cfa + offset;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d) from the stack, saved at CFA plus offset %d [saved at 0x%" PRIx64 "]",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
offset, regloc.location.target_memory_location);
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsInOtherRegister())
{
uint32_t unwindplan_regnum = unwindplan_regloc.GetRegisterNumber();
RegisterNumber row_regnum (m_thread, unwindplan_registerkind, unwindplan_regnum);
if (row_regnum.GetAsKind (eRegisterKindLLDB) == LLDB_INVALID_REGNUM)
{
UnwindLogMsg ("could not supply caller's %s (%d) location - was saved in another reg but couldn't convert that regnum",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
regloc.type = UnwindLLDB::RegisterLocation::eRegisterInRegister;
regloc.location.register_number = row_regnum.GetAsKind (eRegisterKindLLDB);
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d), saved in register %s (%d)",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB),
row_regnum.GetName(), row_regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
if (unwindplan_regloc.IsDWARFExpression() || unwindplan_regloc.IsAtDWARFExpression())
{
DataExtractor dwarfdata (unwindplan_regloc.GetDWARFExpressionBytes(),
unwindplan_regloc.GetDWARFExpressionLength(),
process->GetByteOrder(), process->GetAddressByteSize());
ModuleSP opcode_ctx;
DWARFExpression dwarfexpr (opcode_ctx,
dwarfdata,
nullptr,
0,
unwindplan_regloc.GetDWARFExpressionLength());
dwarfexpr.SetRegisterKind (unwindplan_registerkind);
Value result;
Error error;
if (dwarfexpr.Evaluate (&exe_ctx, nullptr, nullptr, this, 0, nullptr, nullptr, result, &error))
{
addr_t val;
val = result.GetScalar().ULongLong();
if (unwindplan_regloc.IsDWARFExpression())
{
regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
regloc.location.inferred_value = val;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d) via DWARF expression (IsDWARFExpression)",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
else
{
regloc.type = UnwindLLDB::RegisterLocation::eRegisterSavedAtMemoryLocation;
regloc.location.target_memory_location = val;
m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
UnwindLogMsg ("supplying caller's register %s (%d) via DWARF expression (IsAtDWARFExpression)",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterFound;
}
}
UnwindLogMsg ("tried to use IsDWARFExpression or IsAtDWARFExpression for %s (%d) but failed",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
UnwindLogMsg ("no save location for %s (%d) in this stack frame",
regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
// FIXME UnwindPlan::Row types atDWARFExpression and isDWARFExpression are unsupported.
return UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
}
// TryFallbackUnwindPlan() -- this method is a little tricky.
//
// When this is called, the frame above -- the caller frame, the "previous" frame --
// is invalid or bad.
//
// Instead of stopping the stack walk here, we'll try a different UnwindPlan and see
// if we can get a valid frame above us.
//
// This most often happens when an unwind plan based on assembly instruction inspection
// is not correct -- mostly with hand-written assembly functions or functions where the
// stack frame is set up "out of band", e.g. the kernel saved the register context and
// then called an asynchronous trap handler like _sigtramp.
//
// Often in these cases, if we just do a dumb stack walk we'll get past this tricky
// frame and our usual techniques can continue to be used.
bool
RegisterContextLLDB::TryFallbackUnwindPlan ()
{
if (m_fallback_unwind_plan_sp.get() == nullptr)
return false;
if (m_full_unwind_plan_sp.get() == nullptr)
return false;
if (m_full_unwind_plan_sp.get() == m_fallback_unwind_plan_sp.get()
|| m_full_unwind_plan_sp->GetSourceName() == m_fallback_unwind_plan_sp->GetSourceName())
{
return false;
}
// If a compiler generated unwind plan failed, trying the arch default unwindplan
// isn't going to do any better.
if (m_full_unwind_plan_sp->GetSourcedFromCompiler() == eLazyBoolYes)
return false;
// Get the caller's pc value and our own CFA value.
// Swap in the fallback unwind plan, re-fetch the caller's pc value and CFA value.
// If they're the same, then the fallback unwind plan provides no benefit.
RegisterNumber pc_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
addr_t old_caller_pc_value = LLDB_INVALID_ADDRESS;
addr_t new_caller_pc_value = LLDB_INVALID_ADDRESS;
addr_t old_this_frame_cfa_value = m_cfa;
UnwindLLDB::RegisterLocation regloc;
if (SavedLocationForRegister (pc_regnum.GetAsKind (eRegisterKindLLDB), regloc) == UnwindLLDB::RegisterSearchResult::eRegisterFound)
{
const RegisterInfo *reg_info = GetRegisterInfoAtIndex(pc_regnum.GetAsKind (eRegisterKindLLDB));
if (reg_info)
{
RegisterValue reg_value;
if (ReadRegisterValueFromRegisterLocation (regloc, reg_info, reg_value))
{
old_caller_pc_value = reg_value.GetAsUInt64();
}
}
}
// This is a tricky wrinkle! If SavedLocationForRegister() detects a really impossible
// register location for the full unwind plan, it may call ForceSwitchToFallbackUnwindPlan()
// which in turn replaces the full unwindplan with the fallback... in short, we're done,
// we're using the fallback UnwindPlan.
// We checked if m_fallback_unwind_plan_sp was nullptr at the top -- the only way it
// became nullptr since then is via SavedLocationForRegister().
if (m_fallback_unwind_plan_sp.get() == nullptr)
return true;
// Switch the full UnwindPlan to be the fallback UnwindPlan. If we decide this isn't
// working, we need to restore.
// We'll also need to save & restore the value of the m_cfa ivar. Save is down below a bit in 'old_cfa'.
UnwindPlanSP original_full_unwind_plan_sp = m_full_unwind_plan_sp;
addr_t old_cfa = m_cfa;
m_registers.clear();
m_full_unwind_plan_sp = m_fallback_unwind_plan_sp;
UnwindPlan::RowSP active_row = m_fallback_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
if (active_row && active_row->GetCFAValue().GetValueType() != UnwindPlan::Row::CFAValue::unspecified)
{
addr_t new_cfa;
if (!ReadCFAValueForRow (m_fallback_unwind_plan_sp->GetRegisterKind(), active_row, new_cfa)
|| new_cfa == 0 || new_cfa == 1 || new_cfa == LLDB_INVALID_ADDRESS)
{
UnwindLogMsg ("failed to get cfa with fallback unwindplan");
m_fallback_unwind_plan_sp.reset();
m_full_unwind_plan_sp = original_full_unwind_plan_sp;
m_cfa = old_cfa;
return false;
}
m_cfa = new_cfa;
if (SavedLocationForRegister (pc_regnum.GetAsKind (eRegisterKindLLDB), regloc) == UnwindLLDB::RegisterSearchResult::eRegisterFound)
{
const RegisterInfo *reg_info = GetRegisterInfoAtIndex(pc_regnum.GetAsKind (eRegisterKindLLDB));
if (reg_info)
{
RegisterValue reg_value;
if (ReadRegisterValueFromRegisterLocation (regloc, reg_info, reg_value))
{
new_caller_pc_value = reg_value.GetAsUInt64();
}
}
}
if (new_caller_pc_value == LLDB_INVALID_ADDRESS)
{
UnwindLogMsg ("failed to get a pc value for the caller frame with the fallback unwind plan");
m_fallback_unwind_plan_sp.reset();
m_full_unwind_plan_sp = original_full_unwind_plan_sp;
m_cfa = old_cfa;
return false;
}
if (old_caller_pc_value != LLDB_INVALID_ADDRESS)
{
if (old_caller_pc_value == new_caller_pc_value && new_cfa == old_this_frame_cfa_value)
{
UnwindLogMsg ("fallback unwind plan got the same values for this frame CFA and caller frame pc, not using");
m_fallback_unwind_plan_sp.reset();
m_full_unwind_plan_sp = original_full_unwind_plan_sp;
m_cfa = old_cfa;
return false;
}
}
UnwindLogMsg ("trying to unwind from this function with the UnwindPlan '%s' because UnwindPlan '%s' failed.",
m_fallback_unwind_plan_sp->GetSourceName().GetCString(),
original_full_unwind_plan_sp->GetSourceName().GetCString());
// We've copied the fallback unwind plan into the full - now clear the fallback.
m_fallback_unwind_plan_sp.reset();
}
return true;
}
bool
RegisterContextLLDB::ForceSwitchToFallbackUnwindPlan ()
{
if (m_fallback_unwind_plan_sp.get() == NULL)
return false;
if (m_full_unwind_plan_sp.get() == NULL)
return false;
if (m_full_unwind_plan_sp.get() == m_fallback_unwind_plan_sp.get()
|| m_full_unwind_plan_sp->GetSourceName() == m_fallback_unwind_plan_sp->GetSourceName())
{
return false;
}
UnwindPlan::RowSP active_row = m_fallback_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
if (active_row && active_row->GetCFAValue().GetValueType() != UnwindPlan::Row::CFAValue::unspecified)
{
addr_t new_cfa;
if (!ReadCFAValueForRow (m_fallback_unwind_plan_sp->GetRegisterKind(), active_row, new_cfa)
|| new_cfa == 0 || new_cfa == 1 || new_cfa == LLDB_INVALID_ADDRESS)
{
UnwindLogMsg ("failed to get cfa with fallback unwindplan");
m_fallback_unwind_plan_sp.reset();
return false;
}
m_full_unwind_plan_sp = m_fallback_unwind_plan_sp;
m_fallback_unwind_plan_sp.reset();
m_registers.clear();
m_cfa = new_cfa;
UnwindLogMsg ("switched unconditionally to the fallback unwindplan %s", m_full_unwind_plan_sp->GetSourceName().GetCString());
return true;
}
return false;
}
bool
RegisterContextLLDB::ReadCFAValueForRow (lldb::RegisterKind row_register_kind,
const UnwindPlan::RowSP &row,
addr_t &cfa_value)
{
RegisterValue reg_value;
cfa_value = LLDB_INVALID_ADDRESS;
addr_t cfa_reg_contents;
switch (row->GetCFAValue().GetValueType())
{
case UnwindPlan::Row::CFAValue::isRegisterDereferenced:
{
RegisterNumber cfa_reg (m_thread, row_register_kind, row->GetCFAValue().GetRegisterNumber());
if (ReadGPRValue (cfa_reg, cfa_reg_contents))
{
const RegisterInfo *reg_info = GetRegisterInfoAtIndex (cfa_reg.GetAsKind (eRegisterKindLLDB));
RegisterValue reg_value;
if (reg_info)
{
Error error = ReadRegisterValueFromMemory(reg_info,
cfa_reg_contents,
reg_info->byte_size,
reg_value);
if (error.Success ())
{
cfa_value = reg_value.GetAsUInt64();
UnwindLogMsg ("CFA value via dereferencing reg %s (%d): reg has val 0x%" PRIx64 ", CFA value is 0x%" PRIx64,
cfa_reg.GetName(), cfa_reg.GetAsKind (eRegisterKindLLDB),
cfa_reg_contents, cfa_value);
return true;
}
else
{
UnwindLogMsg ("Tried to deref reg %s (%d) [0x%" PRIx64 "] but memory read failed.",
cfa_reg.GetName(), cfa_reg.GetAsKind (eRegisterKindLLDB),
cfa_reg_contents);
}
}
}
break;
}
case UnwindPlan::Row::CFAValue::isRegisterPlusOffset:
{
RegisterNumber cfa_reg (m_thread, row_register_kind, row->GetCFAValue().GetRegisterNumber());
if (ReadGPRValue (cfa_reg, cfa_reg_contents))
{
if (cfa_reg_contents == LLDB_INVALID_ADDRESS || cfa_reg_contents == 0 || cfa_reg_contents == 1)
{
UnwindLogMsg ("Got an invalid CFA register value - reg %s (%d), value 0x%" PRIx64,
cfa_reg.GetName(), cfa_reg.GetAsKind (eRegisterKindLLDB),
cfa_reg_contents);
cfa_reg_contents = LLDB_INVALID_ADDRESS;
return false;
}
cfa_value = cfa_reg_contents + row->GetCFAValue().GetOffset();
UnwindLogMsg ("CFA is 0x%" PRIx64 ": Register %s (%d) contents are 0x%" PRIx64 ", offset is %d",
cfa_value,
cfa_reg.GetName(), cfa_reg.GetAsKind (eRegisterKindLLDB),
cfa_reg_contents, row->GetCFAValue().GetOffset());
return true;
}
break;
}
case UnwindPlan::Row::CFAValue::isDWARFExpression:
{
ExecutionContext exe_ctx(m_thread.shared_from_this());
Process *process = exe_ctx.GetProcessPtr();
DataExtractor dwarfdata (row->GetCFAValue().GetDWARFExpressionBytes(),
row->GetCFAValue().GetDWARFExpressionLength(),
process->GetByteOrder(), process->GetAddressByteSize());
ModuleSP opcode_ctx;
DWARFExpression dwarfexpr (opcode_ctx,
dwarfdata,
nullptr,
0,
row->GetCFAValue().GetDWARFExpressionLength());
dwarfexpr.SetRegisterKind (row_register_kind);
Value result;
Error error;
if (dwarfexpr.Evaluate (&exe_ctx, nullptr, nullptr, this, 0, nullptr, nullptr, result, &error))
{
cfa_value = result.GetScalar().ULongLong();
UnwindLogMsg ("CFA value set by DWARF expression is 0x%" PRIx64, cfa_value);
return true;
}
UnwindLogMsg ("Failed to set CFA value via DWARF expression: %s", error.AsCString());
break;
}
default:
return false;
}
return false;
}
// Retrieve a general purpose register value for THIS frame, as saved by the NEXT frame, i.e. the frame that
// this frame called. e.g.
//
// foo () { }
// bar () { foo (); }
// main () { bar (); }
//
// stopped in foo() so
// frame 0 - foo
// frame 1 - bar
// frame 2 - main
// and this RegisterContext is for frame 1 (bar) - if we want to get the pc value for frame 1, we need to ask
// where frame 0 (the "next" frame) saved that and retrieve the value.
bool
RegisterContextLLDB::ReadGPRValue (lldb::RegisterKind register_kind, uint32_t regnum, addr_t &value)
{
if (!IsValid())
return false;
uint32_t lldb_regnum;
if (register_kind == eRegisterKindLLDB)
{
lldb_regnum = regnum;
}
else if (!m_thread.GetRegisterContext()->ConvertBetweenRegisterKinds (register_kind, regnum, eRegisterKindLLDB, lldb_regnum))
{
return false;
}
const RegisterInfo *reg_info = GetRegisterInfoAtIndex(lldb_regnum);
RegisterValue reg_value;
// if this is frame 0 (currently executing frame), get the requested reg contents from the actual thread registers
if (IsFrameZero ())
{
if (m_thread.GetRegisterContext()->ReadRegister (reg_info, reg_value))
{
value = reg_value.GetAsUInt64();
return true;
}
return false;
}
bool pc_register = false;
uint32_t generic_regnum;
if (register_kind == eRegisterKindGeneric
&& (regnum == LLDB_REGNUM_GENERIC_PC || regnum == LLDB_REGNUM_GENERIC_RA))
{
pc_register = true;
}
else if (m_thread.GetRegisterContext()->ConvertBetweenRegisterKinds (register_kind, regnum, eRegisterKindGeneric, generic_regnum)
&& (generic_regnum == LLDB_REGNUM_GENERIC_PC || generic_regnum == LLDB_REGNUM_GENERIC_RA))
{
pc_register = true;
}
lldb_private::UnwindLLDB::RegisterLocation regloc;
if (!m_parent_unwind.SearchForSavedLocationForRegister (lldb_regnum, regloc, m_frame_number - 1, pc_register))
{
return false;
}
if (ReadRegisterValueFromRegisterLocation (regloc, reg_info, reg_value))
{
value = reg_value.GetAsUInt64();
return true;
}
return false;
}
bool
RegisterContextLLDB::ReadGPRValue (const RegisterNumber &regnum, addr_t &value)
{
return ReadGPRValue (regnum.GetRegisterKind(), regnum.GetRegisterNumber(), value);
}
// Find the value of a register in THIS frame
bool
RegisterContextLLDB::ReadRegister (const RegisterInfo *reg_info, RegisterValue &value)
{
if (!IsValid())
return false;
const uint32_t lldb_regnum = reg_info->kinds[eRegisterKindLLDB];
UnwindLogMsgVerbose ("looking for register saved location for reg %d", lldb_regnum);
// If this is the 0th frame, hand this over to the live register context
if (IsFrameZero ())
{
UnwindLogMsgVerbose ("passing along to the live register context for reg %d", lldb_regnum);
return m_thread.GetRegisterContext()->ReadRegister (reg_info, value);
}
bool is_pc_regnum = false;
if (reg_info->kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_PC
|| reg_info->kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_RA)
{
is_pc_regnum = true;
}
lldb_private::UnwindLLDB::RegisterLocation regloc;
// Find out where the NEXT frame saved THIS frame's register contents
if (!m_parent_unwind.SearchForSavedLocationForRegister (lldb_regnum, regloc, m_frame_number - 1, is_pc_regnum))
return false;
return ReadRegisterValueFromRegisterLocation (regloc, reg_info, value);
}
bool
RegisterContextLLDB::WriteRegister (const RegisterInfo *reg_info, const RegisterValue &value)
{
if (!IsValid())
return false;
const uint32_t lldb_regnum = reg_info->kinds[eRegisterKindLLDB];
UnwindLogMsgVerbose ("looking for register saved location for reg %d", lldb_regnum);
// If this is the 0th frame, hand this over to the live register context
if (IsFrameZero ())
{
UnwindLogMsgVerbose ("passing along to the live register context for reg %d", lldb_regnum);
return m_thread.GetRegisterContext()->WriteRegister (reg_info, value);
}
lldb_private::UnwindLLDB::RegisterLocation regloc;
// Find out where the NEXT frame saved THIS frame's register contents
if (!m_parent_unwind.SearchForSavedLocationForRegister (lldb_regnum, regloc, m_frame_number - 1, false))
return false;
return WriteRegisterValueToRegisterLocation (regloc, reg_info, value);
}
// Don't need to implement this one
bool
RegisterContextLLDB::ReadAllRegisterValues (lldb::DataBufferSP &data_sp)
{
return false;
}
// Don't need to implement this one
bool
RegisterContextLLDB::WriteAllRegisterValues (const lldb::DataBufferSP& data_sp)
{
return false;
}
// Retrieve the pc value for THIS from
bool
RegisterContextLLDB::GetCFA (addr_t& cfa)
{
if (!IsValid())
{
return false;
}
if (m_cfa == LLDB_INVALID_ADDRESS)
{
return false;
}
cfa = m_cfa;
return true;
}
RegisterContextLLDB::SharedPtr
RegisterContextLLDB::GetNextFrame () const
{
RegisterContextLLDB::SharedPtr regctx;
if (m_frame_number == 0)
return regctx;
return m_parent_unwind.GetRegisterContextForFrameNum (m_frame_number - 1);
}
RegisterContextLLDB::SharedPtr
RegisterContextLLDB::GetPrevFrame () const
{
RegisterContextLLDB::SharedPtr regctx;
return m_parent_unwind.GetRegisterContextForFrameNum (m_frame_number + 1);
}
// Retrieve the address of the start of the function of THIS frame
bool
RegisterContextLLDB::GetStartPC (addr_t& start_pc)
{
if (!IsValid())
return false;
if (!m_start_pc.IsValid())
{
return ReadPC (start_pc);
}
start_pc = m_start_pc.GetLoadAddress (CalculateTarget().get());
return true;
}
// Retrieve the current pc value for THIS frame, as saved by the NEXT frame.
bool
RegisterContextLLDB::ReadPC (addr_t& pc)
{
if (!IsValid())
return false;
bool above_trap_handler = false;
if (GetNextFrame().get() && GetNextFrame()->IsValid() && GetNextFrame()->IsTrapHandlerFrame())
above_trap_handler = true;
if (ReadGPRValue (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc))
{
// A pc value of 0 or 1 is impossible in the middle of the stack -- it indicates the end of a stack walk.
// On the currently executing frame (or such a frame interrupted asynchronously by sigtramp et al) this may
// occur if code has jumped through a NULL pointer -- we want to be able to unwind past that frame to help
// find the bug.
if (m_all_registers_available == false
&& above_trap_handler == false
&& (pc == 0 || pc == 1))
{
return false;
}
else
{
return true;
}
}
else
{
return false;
}
}
void
RegisterContextLLDB::UnwindLogMsg (const char *fmt, ...)
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log)
{
va_list args;
va_start (args, fmt);
char *logmsg;
if (vasprintf (&logmsg, fmt, args) == -1 || logmsg == NULL)
{
if (logmsg)
free (logmsg);
va_end (args);
return;
}
va_end (args);
log->Printf ("%*sth%d/fr%u %s",
m_frame_number < 100 ? m_frame_number : 100, "", m_thread.GetIndexID(), m_frame_number,
logmsg);
free (logmsg);
}
}
void
RegisterContextLLDB::UnwindLogMsgVerbose (const char *fmt, ...)
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log && log->GetVerbose())
{
va_list args;
va_start (args, fmt);
char *logmsg;
if (vasprintf (&logmsg, fmt, args) == -1 || logmsg == NULL)
{
if (logmsg)
free (logmsg);
va_end (args);
return;
}
va_end (args);
log->Printf ("%*sth%d/fr%u %s",
m_frame_number < 100 ? m_frame_number : 100, "", m_thread.GetIndexID(), m_frame_number,
logmsg);
free (logmsg);
}
}