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llvm-project/lldb/source/Symbol/DWARFCallFrameInfo.cpp

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//===-- DWARFCallFrameInfo.cpp ----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// C Includes
// C++ Includes
#include <list>
#include "lldb/Core/Log.h"
#include "lldb/Core/Section.h"
#include "lldb/Core/ArchSpec.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/Section.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/DWARFCallFrameInfo.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Thread.h"
using namespace lldb;
using namespace lldb_private;
DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile& objfile, SectionSP& section_sp, lldb::RegisterKind reg_kind, bool is_eh_frame) :
m_objfile (objfile),
m_section_sp (section_sp),
m_reg_kind (reg_kind), // The flavor of registers that the CFI data uses (enum RegisterKind)
m_flags (),
m_cie_map (),
m_cfi_data (),
m_cfi_data_initialized (false),
m_fde_index (),
m_fde_index_initialized (false),
m_is_eh_frame (is_eh_frame)
{
}
DWARFCallFrameInfo::~DWARFCallFrameInfo()
{
}
bool
DWARFCallFrameInfo::GetAddressRange (Address addr, AddressRange &range)
{
FDEEntry fde_entry;
if (GetFDEEntryByAddress (addr, fde_entry) == false)
return false;
range = fde_entry.bounds;
return true;
}
bool
DWARFCallFrameInfo::GetUnwindPlan (Address addr, UnwindPlan& unwind_plan)
{
FDEEntry fde_entry;
if (GetFDEEntryByAddress (addr, fde_entry) == false)
return false;
return FDEToUnwindPlan (fde_entry.offset, addr, unwind_plan);
}
bool
DWARFCallFrameInfo::GetFDEEntryByAddress (Address addr, FDEEntry& fde_entry)
{
if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted())
return false;
GetFDEIndex();
struct FDEEntry searchfde;
searchfde.bounds = AddressRange (addr, 1);
std::vector<FDEEntry>::const_iterator idx;
if (m_fde_index.size() == 0)
return false;
idx = std::lower_bound (m_fde_index.begin(), m_fde_index.end(), searchfde);
if (idx == m_fde_index.end())
{
--idx;
}
if (idx != m_fde_index.begin() && idx->bounds.GetBaseAddress().GetOffset() != addr.GetOffset())
{
--idx;
}
if (idx->bounds.ContainsFileAddress (addr))
{
fde_entry = *idx;
return true;
}
return false;
}
const DWARFCallFrameInfo::CIE*
DWARFCallFrameInfo::GetCIE(dw_offset_t cie_offset)
{
cie_map_t::iterator pos = m_cie_map.find(cie_offset);
if (pos != m_cie_map.end())
{
// Parse and cache the CIE
if (pos->second.get() == NULL)
pos->second = ParseCIE (cie_offset);
return pos->second.get();
}
return NULL;
}
DWARFCallFrameInfo::CIESP
DWARFCallFrameInfo::ParseCIE (const dw_offset_t cie_offset)
{
CIESP cie_sp(new CIE(cie_offset));
dw_offset_t offset = cie_offset;
if (m_cfi_data_initialized == false)
GetCFIData();
const uint32_t length = m_cfi_data.GetU32(&offset);
const dw_offset_t cie_id = m_cfi_data.GetU32(&offset);
const dw_offset_t end_offset = cie_offset + length + 4;
if (length > 0 && ((!m_is_eh_frame && cie_id == 0xfffffffful) || (m_is_eh_frame && cie_id == 0ul)))
{
size_t i;
// cie.offset = cie_offset;
// cie.length = length;
// cie.cieID = cieID;
cie_sp->ptr_encoding = DW_EH_PE_absptr;
cie_sp->version = m_cfi_data.GetU8(&offset);
for (i=0; i<CFI_AUG_MAX_SIZE; ++i)
{
cie_sp->augmentation[i] = m_cfi_data.GetU8(&offset);
if (cie_sp->augmentation[i] == '\0')
{
// Zero out remaining bytes in augmentation string
for (size_t j = i+1; j<CFI_AUG_MAX_SIZE; ++j)
cie_sp->augmentation[j] = '\0';
break;
}
}
if (i == CFI_AUG_MAX_SIZE && cie_sp->augmentation[CFI_AUG_MAX_SIZE-1] != '\0')
{
Host::SystemLog (Host::eSystemLogError, "CIE parse error: CIE augmentation string was too large for the fixed sized buffer of %d bytes.\n", CFI_AUG_MAX_SIZE);
return cie_sp;
}
cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(&offset);
cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(&offset);
cie_sp->return_addr_reg_num = m_cfi_data.GetU8(&offset);
if (cie_sp->augmentation[0])
{
// Get the length of the eh_frame augmentation data
// which starts with a ULEB128 length in bytes
const size_t aug_data_len = (size_t)m_cfi_data.GetULEB128(&offset);
const size_t aug_data_end = offset + aug_data_len;
const size_t aug_str_len = strlen(cie_sp->augmentation);
// A 'z' may be present as the first character of the string.
// If present, the Augmentation Data field shall be present.
// The contents of the Augmentation Data shall be intepreted
// according to other characters in the Augmentation String.
if (cie_sp->augmentation[0] == 'z')
{
// Extract the Augmentation Data
size_t aug_str_idx = 0;
for (aug_str_idx = 1; aug_str_idx < aug_str_len; aug_str_idx++)
{
char aug = cie_sp->augmentation[aug_str_idx];
switch (aug)
{
case 'L':
// Indicates the presence of one argument in the
// Augmentation Data of the CIE, and a corresponding
// argument in the Augmentation Data of the FDE. The
// argument in the Augmentation Data of the CIE is
// 1-byte and represents the pointer encoding used
// for the argument in the Augmentation Data of the
// FDE, which is the address of a language-specific
// data area (LSDA). The size of the LSDA pointer is
// specified by the pointer encoding used.
m_cfi_data.GetU8(&offset);
break;
case 'P':
// Indicates the presence of two arguments in the
// Augmentation Data of the cie_sp-> The first argument
// is 1-byte and represents the pointer encoding
// used for the second argument, which is the
// address of a personality routine handler. The
// size of the personality routine pointer is
// specified by the pointer encoding used.
{
uint8_t arg_ptr_encoding = m_cfi_data.GetU8(&offset);
m_cfi_data.GetGNUEHPointer(&offset, arg_ptr_encoding, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS);
}
break;
case 'R':
// A 'R' may be present at any position after the
// first character of the string. The Augmentation
// Data shall include a 1 byte argument that
// represents the pointer encoding for the address
// pointers used in the FDE.
cie_sp->ptr_encoding = m_cfi_data.GetU8(&offset);
break;
}
}
}
else if (strcmp(cie_sp->augmentation, "eh") == 0)
{
// If the Augmentation string has the value "eh", then
// the EH Data field shall be present
}
// Set the offset to be the end of the augmentation data just in case
// we didn't understand any of the data.
offset = (uint32_t)aug_data_end;
}
if (end_offset > offset)
{
cie_sp->inst_offset = offset;
cie_sp->inst_length = end_offset - offset;
}
while (offset < end_offset)
{
uint8_t inst = m_cfi_data.GetU8(&offset);
uint8_t primary_opcode = inst & 0xC0;
uint8_t extended_opcode = inst & 0x3F;
if (extended_opcode == DW_CFA_def_cfa)
{
// Takes two unsigned LEB128 operands representing a register
// number and a (non-factored) offset. The required action
// is to define the current CFA rule to use the provided
// register and offset.
uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
cie_sp->initial_row.SetCFARegister (reg_num);
cie_sp->initial_row.SetCFAOffset (op_offset);
continue;
}
if (primary_opcode == DW_CFA_offset)
{
// 0x80 - high 2 bits are 0x2, lower 6 bits are register.
// Takes two arguments: an unsigned LEB128 constant representing a
// factored offset and a register number. The required action is to
// change the rule for the register indicated by the register number
// to be an offset(N) rule with a value of
// (N = factored offset * data_align).
uint32_t reg_num = extended_opcode;
int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * cie_sp->data_align;
UnwindPlan::Row::RegisterLocation reg_location;
reg_location.SetAtCFAPlusOffset(op_offset);
cie_sp->initial_row.SetRegisterInfo (reg_num, reg_location);
continue;
}
if (extended_opcode == DW_CFA_nop)
{
continue;
}
break; // Stop if we hit an unrecognized opcode
}
}
return cie_sp;
}
void
DWARFCallFrameInfo::GetCFIData()
{
if (m_cfi_data_initialized == false)
{
LogSP log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log)
m_objfile.GetModule()->LogMessage(log.get(), "Reading EH frame info");
m_objfile.ReadSectionData (m_section_sp.get(), m_cfi_data);
m_cfi_data_initialized = true;
}
}
// Scan through the eh_frame or debug_frame section looking for FDEs and noting the start/end addresses
// of the functions and a pointer back to the function's FDE for later expansion.
// Internalize CIEs as we come across them.
void
DWARFCallFrameInfo::GetFDEIndex ()
{
if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted())
return;
if (m_fde_index_initialized)
return;
Mutex::Locker locker(m_fde_index_mutex);
if (m_fde_index_initialized) // if two threads hit the locker
return;
dw_offset_t offset = 0;
if (m_cfi_data_initialized == false)
GetCFIData();
while (m_cfi_data.ValidOffsetForDataOfSize (offset, 8))
{
const dw_offset_t current_entry = offset;
uint32_t len = m_cfi_data.GetU32 (&offset);
dw_offset_t next_entry = current_entry + len + 4;
dw_offset_t cie_id = m_cfi_data.GetU32 (&offset);
if (cie_id == 0 || cie_id == UINT32_MAX)
{
m_cie_map[current_entry] = ParseCIE (current_entry);
offset = next_entry;
continue;
}
const dw_offset_t cie_offset = current_entry + 4 - cie_id;
const CIE *cie = GetCIE (cie_offset);
if (cie)
{
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t addr = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr);
lldb::addr_t length = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr);
FDEEntry fde;
fde.bounds = AddressRange (addr, length, m_objfile.GetSectionList());
fde.offset = current_entry;
m_fde_index.push_back(fde);
}
else
{
Host::SystemLog (Host::eSystemLogError,
"error: unable to find CIE at 0x%8.8x for cie_id = 0x%8.8x for entry at 0x%8.8x.\n",
cie_offset,
cie_id,
current_entry);
}
offset = next_entry;
}
std::sort (m_fde_index.begin(), m_fde_index.end());
m_fde_index_initialized = true;
}
bool
DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t offset, Address startaddr, UnwindPlan& unwind_plan)
{
dw_offset_t current_entry = offset;
if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted())
return false;
if (m_cfi_data_initialized == false)
GetCFIData();
uint32_t length = m_cfi_data.GetU32 (&offset);
dw_offset_t cie_offset = m_cfi_data.GetU32 (&offset);
assert (cie_offset != 0 && cie_offset != UINT32_MAX);
// Translate the CIE_id from the eh_frame format, which
// is relative to the FDE offset, into a __eh_frame section
// offset
if (m_is_eh_frame)
{
unwind_plan.SetSourceName ("eh_frame CFI");
cie_offset = current_entry + 4 - cie_offset;
}
else
{
unwind_plan.SetSourceName ("DWARF CFI");
}
const CIE *cie = GetCIE (cie_offset);
assert (cie != NULL);
const dw_offset_t end_offset = current_entry + length + 4;
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t range_base = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr);
lldb::addr_t range_len = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr);
AddressRange range (range_base, m_objfile.GetAddressByteSize(), m_objfile.GetSectionList());
range.SetByteSize (range_len);
if (cie->augmentation[0] == 'z')
{
uint32_t aug_data_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
offset += aug_data_len;
}
uint32_t reg_num = 0;
int32_t op_offset = 0;
uint32_t code_align = cie->code_align;
int32_t data_align = cie->data_align;
unwind_plan.SetPlanValidAddressRange (range);
UnwindPlan::Row *cie_initial_row = new UnwindPlan::Row;
*cie_initial_row = cie->initial_row;
UnwindPlan::RowSP row(cie_initial_row);
unwind_plan.SetRegisterKind (m_reg_kind);
unwind_plan.SetReturnAddressRegister (cie->return_addr_reg_num);
UnwindPlan::Row::RegisterLocation reg_location;
while (m_cfi_data.ValidOffset(offset) && offset < end_offset)
{
uint8_t inst = m_cfi_data.GetU8(&offset);
uint8_t primary_opcode = inst & 0xC0;
uint8_t extended_opcode = inst & 0x3F;
if (primary_opcode)
{
switch (primary_opcode)
{
case DW_CFA_advance_loc : // (Row Creation Instruction)
{ // 0x40 - high 2 bits are 0x1, lower 6 bits are delta
// takes a single argument that represents a constant delta. The
// required action is to create a new table row with a location
// value that is computed by taking the current entry's location
// value and adding (delta * code_align). All other
// values in the new row are initially identical to the current row.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset(extended_opcode * code_align);
}
break;
case DW_CFA_offset :
{ // 0x80 - high 2 bits are 0x2, lower 6 bits are register
// takes two arguments: an unsigned LEB128 constant representing a
// factored offset and a register number. The required action is to
// change the rule for the register indicated by the register number
// to be an offset(N) rule with a value of
// (N = factored offset * data_align).
reg_num = extended_opcode;
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_restore :
{ // 0xC0 - high 2 bits are 0x3, lower 6 bits are register
// takes a single argument that represents a register number. The
// required action is to change the rule for the indicated register
// to the rule assigned it by the initial_instructions in the CIE.
reg_num = extended_opcode;
// We only keep enough register locations around to
// unwind what is in our thread, and these are organized
// by the register index in that state, so we need to convert our
// GCC register number from the EH frame info, to a register index
if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location))
row->SetRegisterInfo (reg_num, reg_location);
}
break;
}
}
else
{
switch (extended_opcode)
{
case DW_CFA_nop : // 0x0
break;
case DW_CFA_set_loc : // 0x1 (Row Creation Instruction)
{
// DW_CFA_set_loc takes a single argument that represents an address.
// The required action is to create a new table row using the
// specified address as the location. All other values in the new row
// are initially identical to the current row. The new location value
// should always be greater than the current one.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SetOffset(m_cfi_data.GetPointer(&offset) - startaddr.GetFileAddress());
}
break;
case DW_CFA_advance_loc1 : // 0x2 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU8(&offset) * code_align);
}
break;
case DW_CFA_advance_loc2 : // 0x3 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU16(&offset) * code_align);
}
break;
case DW_CFA_advance_loc4 : // 0x4 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU32(&offset) * code_align);
}
break;
case DW_CFA_offset_extended : // 0x5
{
// takes two unsigned LEB128 arguments representing a register number
// and a factored offset. This instruction is identical to DW_CFA_offset
// except for the encoding and size of the register argument.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_restore_extended : // 0x6
{
// takes a single unsigned LEB128 argument that represents a register
// number. This instruction is identical to DW_CFA_restore except for
// the encoding and size of the register argument.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location))
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_undefined : // 0x7
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to undefined.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetUndefined();
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_same_value : // 0x8
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to same value.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetSame();
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_register : // 0x9
{
// takes two unsigned LEB128 arguments representing register numbers.
// The required action is to set the rule for the first register to be
// the second register.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetInRegister(other_reg_num);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_remember_state : // 0xA
{
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for every
// register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
unwind_plan.AppendRow (row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
}
break;
case DW_CFA_restore_state : // 0xB
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for every
// register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
{
row = unwind_plan.GetRowAtIndex(unwind_plan.GetRowCount() - 1);
}
break;
case DW_CFA_def_cfa : // 0xC (CFA Definition Instruction)
{
// Takes two unsigned LEB128 operands representing a register
// number and a (non-factored) offset. The required action
// is to define the current CFA rule to use the provided
// register and offset.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFARegister (reg_num);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_register : // 0xD (CFA Definition Instruction)
{
// takes a single unsigned LEB128 argument representing a register
// number. The required action is to define the current CFA rule to
// use the provided register (but to keep the old offset).
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFARegister (reg_num);
}
break;
case DW_CFA_def_cfa_offset : // 0xE (CFA Definition Instruction)
{
// Takes a single unsigned LEB128 operand representing a
// (non-factored) offset. The required action is to define
// the current CFA rule to use the provided offset (but
// to keep the old register).
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_expression : // 0xF (CFA Definition Instruction)
{
size_t block_len = (size_t)m_cfi_data.GetULEB128(&offset);
offset += (uint32_t)block_len;
}
break;
case DW_CFA_expression : // 0x10
{
// Takes two operands: an unsigned LEB128 value representing
// a register number, and a DW_FORM_block value representing a DWARF
// expression. The required action is to change the rule for the
// register indicated by the register number to be an expression(E)
// rule where E is the DWARF expression. That is, the DWARF
// expression computes the address. The value of the CFA is
// pushed on the DWARF evaluation stack prior to execution of
// the DWARF expression.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t *block_data = (uint8_t *)m_cfi_data.GetData(&offset, block_len);
reg_location.SetAtDWARFExpression(block_data, block_len);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_offset_extended_sf : // 0x11
{
// takes two operands: an unsigned LEB128 value representing a
// register number and a signed LEB128 factored offset. This
// instruction is identical to DW_CFA_offset_extended except
//that the second operand is signed and factored.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_def_cfa_sf : // 0x12 (CFA Definition Instruction)
{
// Takes two operands: an unsigned LEB128 value representing
// a register number and a signed LEB128 factored offset.
// This instruction is identical to DW_CFA_def_cfa except
// that the second operand is signed and factored.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
row->SetCFARegister (reg_num);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_offset_sf : // 0x13 (CFA Definition Instruction)
{
// takes a signed LEB128 operand representing a factored
// offset. This instruction is identical to DW_CFA_def_cfa_offset
// except that the operand is signed and factored.
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_val_expression : // 0x16
{
// takes two operands: an unsigned LEB128 value representing a register
// number, and a DW_FORM_block value representing a DWARF expression.
// The required action is to change the rule for the register indicated
// by the register number to be a val_expression(E) rule where E is the
// DWARF expression. That is, the DWARF expression computes the value of
// the given register. The value of the CFA is pushed on the DWARF
// evaluation stack prior to execution of the DWARF expression.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t* block_data = (uint8_t*)m_cfi_data.GetData(&offset, block_len);
//#if defined(__i386__) || defined(__x86_64__)
// // The EH frame info for EIP and RIP contains code that looks for traps to
// // be a specific type and increments the PC.
// // For i386:
// // DW_CFA_val_expression where:
// // eip = DW_OP_breg6(+28), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x34),
// // DW_OP_deref, DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref,
// // DW_OP_dup, DW_OP_lit3, DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne,
// // DW_OP_and, DW_OP_plus
// // This basically does a:
// // eip = ucontenxt.mcontext32->gpr.eip;
// // if (ucontenxt.mcontext32->exc.trapno != 3 && ucontenxt.mcontext32->exc.trapno != 4)
// // eip++;
// //
// // For x86_64:
// // DW_CFA_val_expression where:
// // rip = DW_OP_breg3(+48), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x90), DW_OP_deref,
// // DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref_size(4), DW_OP_dup, DW_OP_lit3,
// // DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, DW_OP_and, DW_OP_plus
// // This basically does a:
// // rip = ucontenxt.mcontext64->gpr.rip;
// // if (ucontenxt.mcontext64->exc.trapno != 3 && ucontenxt.mcontext64->exc.trapno != 4)
// // rip++;
// // The trap comparisons and increments are not needed as it hoses up the unwound PC which
// // is expected to point at least past the instruction that causes the fault/trap. So we
// // take it out by trimming the expression right at the first "DW_OP_swap" opcodes
// if (block_data != NULL && thread->GetPCRegNum(Thread::GCC) == reg_num)
// {
// if (thread->Is64Bit())
// {
// if (block_len > 9 && block_data[8] == DW_OP_swap && block_data[9] == DW_OP_plus_uconst)
// block_len = 8;
// }
// else
// {
// if (block_len > 8 && block_data[7] == DW_OP_swap && block_data[8] == DW_OP_plus_uconst)
// block_len = 7;
// }
// }
//#endif
reg_location.SetIsDWARFExpression(block_data, block_len);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_val_offset : // 0x14
case DW_CFA_val_offset_sf : // 0x15
default:
break;
}
}
}
unwind_plan.AppendRow(row);
return true;
}
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