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llvm-project/lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp

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//===-- UnwindAssembly-x86.cpp ----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "UnwindAssembly-x86.h"
#include "llvm-c/Disassembler.h"
#include "llvm/Support/TargetSelect.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/ArchSpec.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/UnwindAssembly.h"
using namespace lldb;
using namespace lldb_private;
enum CPU
{
k_i386,
k_x86_64
};
enum i386_register_numbers
{
k_machine_eax = 0,
k_machine_ecx = 1,
k_machine_edx = 2,
k_machine_ebx = 3,
k_machine_esp = 4,
k_machine_ebp = 5,
k_machine_esi = 6,
k_machine_edi = 7,
k_machine_eip = 8
};
enum x86_64_register_numbers
{
k_machine_rax = 0,
k_machine_rcx = 1,
k_machine_rdx = 2,
k_machine_rbx = 3,
k_machine_rsp = 4,
k_machine_rbp = 5,
k_machine_rsi = 6,
k_machine_rdi = 7,
k_machine_r8 = 8,
k_machine_r9 = 9,
k_machine_r10 = 10,
k_machine_r11 = 11,
k_machine_r12 = 12,
k_machine_r13 = 13,
k_machine_r14 = 14,
k_machine_r15 = 15,
k_machine_rip = 16
};
struct regmap_ent
{
const char *name;
int machine_regno;
int lldb_regno;
};
static struct regmap_ent i386_register_map[] =
{
{"eax", k_machine_eax, -1},
{"ecx", k_machine_ecx, -1},
{"edx", k_machine_edx, -1},
{"ebx", k_machine_ebx, -1},
{"esp", k_machine_esp, -1},
{"ebp", k_machine_ebp, -1},
{"esi", k_machine_esi, -1},
{"edi", k_machine_edi, -1},
{"eip", k_machine_eip, -1}
};
const int size_of_i386_register_map = llvm::array_lengthof (i386_register_map);
static int i386_register_map_initialized = 0;
static struct regmap_ent x86_64_register_map[] =
{
{"rax", k_machine_rax, -1},
{"rcx", k_machine_rcx, -1},
{"rdx", k_machine_rdx, -1},
{"rbx", k_machine_rbx, -1},
{"rsp", k_machine_rsp, -1},
{"rbp", k_machine_rbp, -1},
{"rsi", k_machine_rsi, -1},
{"rdi", k_machine_rdi, -1},
{"r8", k_machine_r8, -1},
{"r9", k_machine_r9, -1},
{"r10", k_machine_r10, -1},
{"r11", k_machine_r11, -1},
{"r12", k_machine_r12, -1},
{"r13", k_machine_r13, -1},
{"r14", k_machine_r14, -1},
{"r15", k_machine_r15, -1},
{"rip", k_machine_rip, -1}
};
const int size_of_x86_64_register_map = llvm::array_lengthof (x86_64_register_map);
static int x86_64_register_map_initialized = 0;
//-----------------------------------------------------------------------------------------------
// AssemblyParse_x86 local-file class definition & implementation functions
//-----------------------------------------------------------------------------------------------
class AssemblyParse_x86
{
public:
AssemblyParse_x86 (const ExecutionContext &exe_ctx, int cpu, ArchSpec &arch, AddressRange func);
~AssemblyParse_x86 ();
bool get_non_call_site_unwind_plan (UnwindPlan &unwind_plan);
bool augment_unwind_plan_from_call_site (AddressRange& func, UnwindPlan &unwind_plan);
bool get_fast_unwind_plan (AddressRange& func, UnwindPlan &unwind_plan);
bool find_first_non_prologue_insn (Address &address);
private:
enum { kMaxInstructionByteSize = 32 };
bool nonvolatile_reg_p (int machine_regno);
bool push_rbp_pattern_p ();
bool push_0_pattern_p ();
bool mov_rsp_rbp_pattern_p ();
bool sub_rsp_pattern_p (int& amount);
bool add_rsp_pattern_p (int& amount);
bool push_reg_p (int& regno);
bool pop_reg_p (int& regno);
bool push_imm_pattern_p ();
bool mov_reg_to_local_stack_frame_p (int& regno, int& fp_offset);
bool ret_pattern_p ();
bool pop_rbp_pattern_p ();
bool call_next_insn_pattern_p();
uint32_t extract_4 (uint8_t *b);
bool machine_regno_to_lldb_regno (int machine_regno, uint32_t& lldb_regno);
bool instruction_length (Address addr, int &length);
const ExecutionContext m_exe_ctx;
AddressRange m_func_bounds;
Address m_cur_insn;
uint8_t m_cur_insn_bytes[kMaxInstructionByteSize];
uint32_t m_machine_ip_regnum;
uint32_t m_machine_sp_regnum;
uint32_t m_machine_fp_regnum;
uint32_t m_lldb_ip_regnum;
uint32_t m_lldb_sp_regnum;
uint32_t m_lldb_fp_regnum;
int m_wordsize;
int m_cpu;
ArchSpec m_arch;
::LLVMDisasmContextRef m_disasm_context;
DISALLOW_COPY_AND_ASSIGN (AssemblyParse_x86);
};
AssemblyParse_x86::AssemblyParse_x86 (const ExecutionContext &exe_ctx, int cpu, ArchSpec &arch, AddressRange func) :
m_exe_ctx (exe_ctx),
m_func_bounds(func),
m_cur_insn (),
m_machine_ip_regnum (LLDB_INVALID_REGNUM),
m_machine_sp_regnum (LLDB_INVALID_REGNUM),
m_machine_fp_regnum (LLDB_INVALID_REGNUM),
m_lldb_ip_regnum (LLDB_INVALID_REGNUM),
m_lldb_sp_regnum (LLDB_INVALID_REGNUM),
m_lldb_fp_regnum (LLDB_INVALID_REGNUM),
m_wordsize (-1),
m_cpu(cpu),
m_arch(arch)
{
int *initialized_flag = NULL;
if (cpu == k_i386)
{
m_machine_ip_regnum = k_machine_eip;
m_machine_sp_regnum = k_machine_esp;
m_machine_fp_regnum = k_machine_ebp;
m_wordsize = 4;
initialized_flag = &i386_register_map_initialized;
}
else
{
m_machine_ip_regnum = k_machine_rip;
m_machine_sp_regnum = k_machine_rsp;
m_machine_fp_regnum = k_machine_rbp;
m_wordsize = 8;
initialized_flag = &x86_64_register_map_initialized;
}
// we only look at prologue - it will be complete earlier than 512 bytes into func
if (m_func_bounds.GetByteSize() == 0)
m_func_bounds.SetByteSize(512);
Thread *thread = m_exe_ctx.GetThreadPtr();
if (thread && *initialized_flag == 0)
{
RegisterContext *reg_ctx = thread->GetRegisterContext().get();
if (reg_ctx)
{
struct regmap_ent *ent;
int count, i;
if (cpu == k_i386)
{
ent = i386_register_map;
count = size_of_i386_register_map;
}
else
{
ent = x86_64_register_map;
count = size_of_x86_64_register_map;
}
for (i = 0; i < count; i++, ent++)
{
const RegisterInfo *ri = reg_ctx->GetRegisterInfoByName (ent->name);
if (ri)
ent->lldb_regno = ri->kinds[eRegisterKindLLDB];
}
*initialized_flag = 1;
}
}
// on initial construction we may not have a Thread so these have to remain
// uninitialized until we can get a RegisterContext to set up the register map table
if (*initialized_flag == 1)
{
uint32_t lldb_regno;
if (machine_regno_to_lldb_regno (m_machine_sp_regnum, lldb_regno))
m_lldb_sp_regnum = lldb_regno;
if (machine_regno_to_lldb_regno (m_machine_fp_regnum, lldb_regno))
m_lldb_fp_regnum = lldb_regno;
if (machine_regno_to_lldb_regno (m_machine_ip_regnum, lldb_regno))
m_lldb_ip_regnum = lldb_regno;
}
m_disasm_context = ::LLVMCreateDisasm(m_arch.GetTriple().getTriple().c_str(),
(void*)this,
/*TagType=*/1,
NULL,
NULL);
}
AssemblyParse_x86::~AssemblyParse_x86 ()
{
::LLVMDisasmDispose(m_disasm_context);
}
// This function expects an x86 native register number (i.e. the bits stripped out of the
// actual instruction), not an lldb register number.
bool
AssemblyParse_x86::nonvolatile_reg_p (int machine_regno)
{
if (m_cpu == k_i386)
{
switch (machine_regno)
{
case k_machine_ebx:
case k_machine_ebp: // not actually a nonvolatile but often treated as such by convention
case k_machine_esi:
case k_machine_edi:
case k_machine_esp:
return true;
default:
return false;
}
}
if (m_cpu == k_x86_64)
{
switch (machine_regno)
{
case k_machine_rbx:
case k_machine_rsp:
case k_machine_rbp: // not actually a nonvolatile but often treated as such by convention
case k_machine_r12:
case k_machine_r13:
case k_machine_r14:
case k_machine_r15:
return true;
default:
return false;
}
}
return false;
}
// Macro to detect if this is a REX mode prefix byte.
#define REX_W_PREFIX_P(opcode) (((opcode) & (~0x5)) == 0x48)
// The high bit which should be added to the source register number (the "R" bit)
#define REX_W_SRCREG(opcode) (((opcode) & 0x4) >> 2)
// The high bit which should be added to the destination register number (the "B" bit)
#define REX_W_DSTREG(opcode) ((opcode) & 0x1)
// pushq %rbp [0x55]
bool AssemblyParse_x86::push_rbp_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
if (*p == 0x55)
return true;
return false;
}
// pushq $0 ; the first instruction in start() [0x6a 0x00]
bool AssemblyParse_x86::push_0_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
if (*p == 0x6a && *(p + 1) == 0x0)
return true;
return false;
}
// pushq $0
// pushl $0
bool AssemblyParse_x86::push_imm_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
if (*p == 0x68 || *p == 0x6a)
return true;
return false;
}
// movq %rsp, %rbp [0x48 0x8b 0xec] or [0x48 0x89 0xe5]
// movl %esp, %ebp [0x8b 0xec] or [0x89 0xe5]
bool AssemblyParse_x86::mov_rsp_rbp_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
if (m_wordsize == 8 && *p == 0x48)
p++;
if (*(p) == 0x8b && *(p + 1) == 0xec)
return true;
if (*(p) == 0x89 && *(p + 1) == 0xe5)
return true;
return false;
}
// subq $0x20, %rsp
bool AssemblyParse_x86::sub_rsp_pattern_p (int& amount)
{
uint8_t *p = m_cur_insn_bytes;
if (m_wordsize == 8 && *p == 0x48)
p++;
// 8-bit immediate operand
if (*p == 0x83 && *(p + 1) == 0xec)
{
amount = (int8_t) *(p + 2);
return true;
}
// 32-bit immediate operand
if (*p == 0x81 && *(p + 1) == 0xec)
{
amount = (int32_t) extract_4 (p + 2);
return true;
}
return false;
}
// addq $0x20, %rsp
bool AssemblyParse_x86::add_rsp_pattern_p (int& amount)
{
uint8_t *p = m_cur_insn_bytes;
if (m_wordsize == 8 && *p == 0x48)
p++;
// 8-bit immediate operand
if (*p == 0x83 && *(p + 1) == 0xc4)
{
amount = (int8_t) *(p + 2);
return true;
}
// 32-bit immediate operand
if (*p == 0x81 && *(p + 1) == 0xc4)
{
amount = (int32_t) extract_4 (p + 2);
return true;
}
return false;
}
// pushq %rbx
// pushl %ebx
bool AssemblyParse_x86::push_reg_p (int& regno)
{
uint8_t *p = m_cur_insn_bytes;
int regno_prefix_bit = 0;
// If we have a rex prefix byte, check to see if a B bit is set
if (m_wordsize == 8 && *p == 0x41)
{
regno_prefix_bit = 1 << 3;
p++;
}
if (*p >= 0x50 && *p <= 0x57)
{
regno = (*p - 0x50) | regno_prefix_bit;
return true;
}
return false;
}
// popq %rbx
// popl %ebx
bool AssemblyParse_x86::pop_reg_p (int& regno)
{
uint8_t *p = m_cur_insn_bytes;
int regno_prefix_bit = 0;
// If we have a rex prefix byte, check to see if a B bit is set
if (m_wordsize == 8 && *p == 0x41)
{
regno_prefix_bit = 1 << 3;
p++;
}
if (*p >= 0x58 && *p <= 0x5f)
{
regno = (*p - 0x58) | regno_prefix_bit;
return true;
}
return false;
}
// popq %rbp [0x5d]
// popl %ebp [0x5d]
bool AssemblyParse_x86::pop_rbp_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
return (*p == 0x5d);
}
// call $0 [0xe8 0x0 0x0 0x0 0x0]
bool AssemblyParse_x86::call_next_insn_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
return (*p == 0xe8) && (*(p+1) == 0x0) && (*(p+2) == 0x0)
&& (*(p+3) == 0x0) && (*(p+4) == 0x0);
}
// Look for an instruction sequence storing a nonvolatile register
// on to the stack frame.
// movq %rax, -0x10(%rbp) [0x48 0x89 0x45 0xf0]
// movl %eax, -0xc(%ebp) [0x89 0x45 0xf4]
// The offset value returned in rbp_offset will be positive --
// but it must be subtraced from the frame base register to get
// the actual location. The positive value returned for the offset
// is a convention used elsewhere for CFA offsets et al.
bool AssemblyParse_x86::mov_reg_to_local_stack_frame_p (int& regno, int& rbp_offset)
{
uint8_t *p = m_cur_insn_bytes;
int src_reg_prefix_bit = 0;
int target_reg_prefix_bit = 0;
if (m_wordsize == 8 && REX_W_PREFIX_P (*p))
{
src_reg_prefix_bit = REX_W_SRCREG (*p) << 3;
target_reg_prefix_bit = REX_W_DSTREG (*p) << 3;
if (target_reg_prefix_bit == 1)
{
// rbp/ebp don't need a prefix bit - we know this isn't the
// reg we care about.
return false;
}
p++;
}
if (*p == 0x89)
{
/* Mask off the 3-5 bits which indicate the destination register
if this is a ModR/M byte. */
int opcode_destreg_masked_out = *(p + 1) & (~0x38);
/* Is this a ModR/M byte with Mod bits 01 and R/M bits 101
and three bits between them, e.g. 01nnn101
We're looking for a destination of ebp-disp8 or ebp-disp32. */
int immsize;
if (opcode_destreg_masked_out == 0x45)
immsize = 2;
else if (opcode_destreg_masked_out == 0x85)
immsize = 4;
else
return false;
int offset = 0;
if (immsize == 2)
offset = (int8_t) *(p + 2);
if (immsize == 4)
offset = (uint32_t) extract_4 (p + 2);
if (offset > 0)
return false;
regno = ((*(p + 1) >> 3) & 0x7) | src_reg_prefix_bit;
rbp_offset = offset > 0 ? offset : -offset;
return true;
}
return false;
}
// ret [0xc9] or [0xc2 imm8] or [0xca imm8]
bool
AssemblyParse_x86::ret_pattern_p ()
{
uint8_t *p = m_cur_insn_bytes;
if (*p == 0xc9 || *p == 0xc2 || *p == 0xca || *p == 0xc3)
return true;
return false;
}
uint32_t
AssemblyParse_x86::extract_4 (uint8_t *b)
{
uint32_t v = 0;
for (int i = 3; i >= 0; i--)
v = (v << 8) | b[i];
return v;
}
bool
AssemblyParse_x86::machine_regno_to_lldb_regno (int machine_regno, uint32_t &lldb_regno)
{
struct regmap_ent *ent;
int count, i;
if (m_cpu == k_i386)
{
ent = i386_register_map;
count = size_of_i386_register_map;
}
else
{
ent = x86_64_register_map;
count = size_of_x86_64_register_map;
}
for (i = 0; i < count; i++, ent++)
{
if (ent->machine_regno == machine_regno)
if (ent->lldb_regno != -1)
{
lldb_regno = ent->lldb_regno;
return true;
}
}
return false;
}
bool
AssemblyParse_x86::instruction_length (Address addr, int &length)
{
const uint32_t max_op_byte_size = m_arch.GetMaximumOpcodeByteSize();
llvm::SmallVector <uint8_t, 32> opcode_data;
opcode_data.resize (max_op_byte_size);
if (!addr.IsValid())
return false;
const bool prefer_file_cache = true;
Error error;
Target *target = m_exe_ctx.GetTargetPtr();
if (target->ReadMemory (addr, prefer_file_cache, opcode_data.data(),
max_op_byte_size, error) == static_cast<size_t>(-1))
{
return false;
}
char out_string[512];
const addr_t pc = addr.GetFileAddress();
const size_t inst_size = ::LLVMDisasmInstruction (m_disasm_context,
opcode_data.data(),
max_op_byte_size,
pc, // PC value
out_string,
sizeof(out_string));
length = inst_size;
return true;
}
bool
AssemblyParse_x86::get_non_call_site_unwind_plan (UnwindPlan &unwind_plan)
{
UnwindPlan::RowSP row(new UnwindPlan::Row);
int non_prologue_insn_count = 0;
m_cur_insn = m_func_bounds.GetBaseAddress ();
int current_func_text_offset = 0;
int current_sp_bytes_offset_from_cfa = 0;
UnwindPlan::Row::RegisterLocation initial_regloc;
Error error;
if (!m_cur_insn.IsValid())
{
return false;
}
unwind_plan.SetPlanValidAddressRange (m_func_bounds);
unwind_plan.SetRegisterKind (eRegisterKindLLDB);
// At the start of the function, find the CFA by adding wordsize to the SP register
row->SetOffset (current_func_text_offset);
row->SetCFARegister (m_lldb_sp_regnum);
row->SetCFAOffset (m_wordsize);
// caller's stack pointer value before the call insn is the CFA address
initial_regloc.SetIsCFAPlusOffset (0);
row->SetRegisterInfo (m_lldb_sp_regnum, initial_regloc);
// saved instruction pointer can be found at CFA - wordsize.
current_sp_bytes_offset_from_cfa = m_wordsize;
initial_regloc.SetAtCFAPlusOffset (-current_sp_bytes_offset_from_cfa);
row->SetRegisterInfo (m_lldb_ip_regnum, initial_regloc);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
const bool prefer_file_cache = true;
Target *target = m_exe_ctx.GetTargetPtr();
while (m_func_bounds.ContainsFileAddress (m_cur_insn) && non_prologue_insn_count < 10)
{
int stack_offset, insn_len;
int machine_regno; // register numbers masked directly out of instructions
uint32_t lldb_regno; // register numbers in lldb's eRegisterKindLLDB numbering scheme
if (!instruction_length (m_cur_insn, insn_len) || insn_len == 0 || insn_len > kMaxInstructionByteSize)
{
// An unrecognized/junk instruction
break;
}
if (target->ReadMemory (m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
insn_len, error) == static_cast<size_t>(-1))
{
// Error reading the instruction out of the file, stop scanning
break;
}
if (push_rbp_pattern_p ())
{
row->SetOffset (current_func_text_offset + insn_len);
current_sp_bytes_offset_from_cfa += m_wordsize;
row->SetCFAOffset (current_sp_bytes_offset_from_cfa);
UnwindPlan::Row::RegisterLocation regloc;
regloc.SetAtCFAPlusOffset (-row->GetCFAOffset());
row->SetRegisterInfo (m_lldb_fp_regnum, regloc);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
goto loopnext;
}
if (mov_rsp_rbp_pattern_p ())
{
row->SetOffset (current_func_text_offset + insn_len);
row->SetCFARegister (m_lldb_fp_regnum);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
goto loopnext;
}
// This is the start() function (or a pthread equivalent), it starts with a pushl $0x0 which puts the
// saved pc value of 0 on the stack. In this case we want to pretend we didn't see a stack movement at all --
// normally the saved pc value is already on the stack by the time the function starts executing.
if (push_0_pattern_p ())
{
goto loopnext;
}
if (push_reg_p (machine_regno))
{
current_sp_bytes_offset_from_cfa += m_wordsize;
bool need_to_push_row = false;
// the PUSH instruction has moved the stack pointer - if the CFA is set in terms of the stack pointer,
// we need to add a new row of instructions.
if (row->GetCFARegister() == m_lldb_sp_regnum)
{
need_to_push_row = true;
row->SetCFAOffset (current_sp_bytes_offset_from_cfa);
}
// record where non-volatile (callee-saved, spilled) registers are saved on the stack
if (nonvolatile_reg_p (machine_regno) && machine_regno_to_lldb_regno (machine_regno, lldb_regno))
{
need_to_push_row = true;
UnwindPlan::Row::RegisterLocation regloc;
regloc.SetAtCFAPlusOffset (-current_sp_bytes_offset_from_cfa);
row->SetRegisterInfo (lldb_regno, regloc);
}
if (need_to_push_row)
{
row->SetOffset (current_func_text_offset + insn_len);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
}
goto loopnext;
}
if (mov_reg_to_local_stack_frame_p (machine_regno, stack_offset) && nonvolatile_reg_p (machine_regno))
{
if (machine_regno_to_lldb_regno (machine_regno, lldb_regno))
{
row->SetOffset (current_func_text_offset + insn_len);
UnwindPlan::Row::RegisterLocation regloc;
// stack_offset for 'movq %r15, -80(%rbp)' will be 80.
// In the Row, we want to express this as the offset from the CFA. If the frame base
// is rbp (like the above instruction), the CFA offset for rbp is probably 16. So we
// want to say that the value is stored at the CFA address - 96.
regloc.SetAtCFAPlusOffset (-(stack_offset + row->GetCFAOffset()));
row->SetRegisterInfo (lldb_regno, regloc);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
goto loopnext;
}
}
if (sub_rsp_pattern_p (stack_offset))
{
current_sp_bytes_offset_from_cfa += stack_offset;
if (row->GetCFARegister() == m_lldb_sp_regnum)
{
row->SetOffset (current_func_text_offset + insn_len);
row->SetCFAOffset (current_sp_bytes_offset_from_cfa);
unwind_plan.AppendRow (row);
// Allocate a new Row, populate it with the existing Row contents.
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
}
goto loopnext;
}
if (ret_pattern_p ())
{
// we know where the end of the function is; set the limit on the PlanValidAddressRange
// in case our initial "high pc" value was overly large
// int original_size = m_func_bounds.GetByteSize();
// int calculated_size = m_cur_insn.GetOffset() - m_func_bounds.GetBaseAddress().GetOffset() + insn_len + 1;
// m_func_bounds.SetByteSize (calculated_size);
// unwind_plan.SetPlanValidAddressRange (m_func_bounds);
break;
}
// FIXME recognize the i386 picbase setup instruction sequence,
// 0x1f16: call 0x1f1b ; main + 11 at /private/tmp/a.c:3
// 0x1f1b: popl %eax
// and record the temporary stack movements if the CFA is not expressed in terms of ebp.
non_prologue_insn_count++;
loopnext:
m_cur_insn.SetOffset (m_cur_insn.GetOffset() + insn_len);
current_func_text_offset += insn_len;
}
// Now look at the byte at the end of the AddressRange for a limited attempt at describing the
// epilogue. We're looking for the sequence
// [ 0x5d ] mov %rbp, %rsp (aka pop %rbp)
// [ 0xc3 ] ret
// or
// [ 0x5d ] mov %rbp, %rsp (aka pop %rbp)
// [ 0xe9 xx xx xx xx ] jmp objc_retainAutoreleaseReturnValue (this is sometimes the final insn in the function)
// or
// [ 0x5d ] mov %rbp, %rsp (aka pop %rbp)
// [ 0xc3 ] ret
// [ 0xe8 xx xx xx xx ] call __stack_chk_fail (this is sometimes the final insn in the function)
// We want to add a Row describing how to unwind when we're stopped on the 'ret' instruction where the
// CFA is no longer defined in terms of rbp, but is now defined in terms of rsp like on function entry.
// (or the 'jmp' instruction in the second case)
uint64_t ret_insn_offset = LLDB_INVALID_ADDRESS;
Address end_of_fun(m_func_bounds.GetBaseAddress());
end_of_fun.SetOffset (end_of_fun.GetOffset() + m_func_bounds.GetByteSize());
if (m_func_bounds.GetByteSize() > 7)
{
uint8_t bytebuf[7];
Address last_seven_bytes(end_of_fun);
last_seven_bytes.SetOffset (last_seven_bytes.GetOffset() - 7);
if (target->ReadMemory (last_seven_bytes, prefer_file_cache, bytebuf, 7,
error) != static_cast<size_t>(-1))
{
if (bytebuf[5] == 0x5d && bytebuf[6] == 0xc3) // mov & ret
{
ret_insn_offset = m_func_bounds.GetByteSize() - 1;
}
else if (bytebuf[1] == 0x5d && bytebuf[2] == 0xe9) // mov & jmp
{
// When the pc is sitting on the 'jmp' instruction, we have the same
// unwind state as if it was sitting on a 'ret' instruction.
ret_insn_offset = m_func_bounds.GetByteSize() - 5;
}
else if (bytebuf[0] == 0x5d && bytebuf[1] == 0xc3 && bytebuf[2] == 0xe8) // mov & ret & call
{
ret_insn_offset = m_func_bounds.GetByteSize() - 6;
}
}
}
else if (m_func_bounds.GetByteSize() > 2)
{
uint8_t bytebuf[2];
Address last_two_bytes(end_of_fun);
last_two_bytes.SetOffset (last_two_bytes.GetOffset() - 2);
if (target->ReadMemory (last_two_bytes, prefer_file_cache, bytebuf, 2,
error) != static_cast<size_t>(-1))
{
if (bytebuf[0] == 0x5d && bytebuf[1] == 0xc3) // mov & ret
{
ret_insn_offset = m_func_bounds.GetByteSize() - 1;
}
}
}
if (ret_insn_offset != LLDB_INVALID_ADDRESS)
{
// Create a fresh, empty Row and RegisterLocation - don't mention any other registers
UnwindPlan::RowSP epi_row(new UnwindPlan::Row);
UnwindPlan::Row::RegisterLocation epi_regloc;
// When the ret instruction is about to be executed, here's our state
epi_row->SetOffset (ret_insn_offset);
epi_row->SetCFARegister (m_lldb_sp_regnum);
epi_row->SetCFAOffset (m_wordsize);
// caller's stack pointer value before the call insn is the CFA address
epi_regloc.SetIsCFAPlusOffset (0);
epi_row->SetRegisterInfo (m_lldb_sp_regnum, epi_regloc);
// saved instruction pointer can be found at CFA - wordsize
epi_regloc.SetAtCFAPlusOffset (-m_wordsize);
epi_row->SetRegisterInfo (m_lldb_ip_regnum, epi_regloc);
unwind_plan.AppendRow (epi_row);
}
unwind_plan.SetSourceName ("assembly insn profiling");
unwind_plan.SetSourcedFromCompiler (eLazyBoolNo);
unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolYes);
return true;
}
bool
AssemblyParse_x86::augment_unwind_plan_from_call_site (AddressRange& func, UnwindPlan &unwind_plan)
{
// Is func address valid?
Address addr_start = func.GetBaseAddress();
if (!addr_start.IsValid())
return false;
// Is original unwind_plan valid?
// unwind_plan should have at least one row which is ABI-default (CFA register is sp),
// and another row in mid-function.
if (unwind_plan.GetRowCount() < 2)
return false;
UnwindPlan::RowSP first_row = unwind_plan.GetRowAtIndex (0);
if (first_row->GetOffset() != 0)
return false;
uint32_t cfa_reg = m_exe_ctx.GetThreadPtr()->GetRegisterContext()
->ConvertRegisterKindToRegisterNumber (unwind_plan.GetRegisterKind(),
first_row->GetCFARegister());
if (cfa_reg != m_lldb_sp_regnum || first_row->GetCFAOffset() != m_wordsize)
return false;
Target *target = m_exe_ctx.GetTargetPtr();
m_cur_insn = func.GetBaseAddress();
uint64_t offset = 0;
int row_id = 1;
bool unwind_plan_updated = false;
UnwindPlan::RowSP row(new UnwindPlan::Row(*first_row));
while (func.ContainsFileAddress (m_cur_insn))
{
int insn_len;
if (!instruction_length (m_cur_insn, insn_len)
|| insn_len == 0 || insn_len > kMaxInstructionByteSize)
{
// An unrecognized/junk instruction.
break;
}
const bool prefer_file_cache = true;
Error error;
if (target->ReadMemory (m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
insn_len, error) == static_cast<size_t>(-1))
{
// Error reading the instruction out of the file, stop scanning.
break;
}
// Advance offsets.
offset += insn_len;
m_cur_insn.SetOffset(m_cur_insn.GetOffset() + insn_len);
// If we already have one row for this instruction, we can continue.
while (row_id < unwind_plan.GetRowCount()
&& unwind_plan.GetRowAtIndex (row_id)->GetOffset() <= offset)
row_id++;
UnwindPlan::RowSP original_row = unwind_plan.GetRowAtIndex (row_id - 1);
if (original_row->GetOffset() == offset)
{
*row = *original_row;
continue;
}
if (row_id == 0)
{
// If we are here, compiler didn't generate CFI for prologue.
// This won't happen to GCC or clang.
// In this case, bail out directly.
return false;
}
// Inspect the instruction to check if we need a new row for it.
cfa_reg = m_exe_ctx.GetThreadPtr()->GetRegisterContext()
->ConvertRegisterKindToRegisterNumber (unwind_plan.GetRegisterKind(),
row->GetCFARegister());
if (cfa_reg == m_lldb_sp_regnum)
{
// CFA register is sp.
// call next instruction
// call 0
// => pop %ebx
if (call_next_insn_pattern_p ())
{
row->SetOffset (offset);
row->SetCFAOffset (m_wordsize + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
// push/pop register
int regno;
if (push_reg_p (regno))
{
row->SetOffset (offset);
row->SetCFAOffset (m_wordsize + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
if (pop_reg_p (regno))
{
// Technically, this might be a nonvolatile register recover in epilogue.
// We should reset RegisterInfo for the register.
// But in practice, previous rule for the register is still valid...
// So we ignore this case.
row->SetOffset (offset);
row->SetCFAOffset (-m_wordsize + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
// push imm
if (push_imm_pattern_p ())
{
row->SetOffset (offset);
row->SetCFAOffset (m_wordsize + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
// add/sub %rsp/%esp
int amount;
if (add_rsp_pattern_p (amount))
{
row->SetOffset (offset);
row->SetCFAOffset (-amount + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
if (sub_rsp_pattern_p (amount))
{
row->SetOffset (offset);
row->SetCFAOffset (amount + row->GetCFAOffset());
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
}
else if (cfa_reg == m_lldb_fp_regnum)
{
// CFA register is fp.
// The only case we care about is epilogue:
// [0x5d] pop %rbp/%ebp
// => [0xc3] ret
if (pop_rbp_pattern_p ())
{
if (target->ReadMemory (m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
1, error) != static_cast<size_t>(-1)
&& ret_pattern_p ())
{
row->SetOffset (offset);
row->SetCFARegister (first_row->GetCFARegister());
row->SetCFAOffset (m_wordsize);
UnwindPlan::RowSP new_row(new UnwindPlan::Row(*row));
unwind_plan.InsertRow (new_row);
unwind_plan_updated = true;
continue;
}
}
}
else
{
// CFA register is not sp or fp.
// This must be hand-written assembly.
// Just trust eh_frame and assume we have finished.
break;
}
}
unwind_plan.SetPlanValidAddressRange (func);
if (unwind_plan_updated)
{
std::string unwind_plan_source (unwind_plan.GetSourceName().AsCString());
unwind_plan_source += " plus augmentation from assembly parsing";
unwind_plan.SetSourceName (unwind_plan_source.c_str());
unwind_plan.SetSourcedFromCompiler (eLazyBoolNo);
}
return true;
}
/* The "fast unwind plan" is valid for functions that follow the usual convention of
using the frame pointer register (ebp, rbp), i.e. the function prologue looks like
push %rbp [0x55]
mov %rsp,%rbp [0x48 0x89 0xe5] (this is a 2-byte insn seq on i386)
*/
bool
AssemblyParse_x86::get_fast_unwind_plan (AddressRange& func, UnwindPlan &unwind_plan)
{
UnwindPlan::RowSP row(new UnwindPlan::Row);
UnwindPlan::Row::RegisterLocation pc_reginfo;
UnwindPlan::Row::RegisterLocation sp_reginfo;
UnwindPlan::Row::RegisterLocation fp_reginfo;
unwind_plan.SetRegisterKind (eRegisterKindLLDB);
if (!func.GetBaseAddress().IsValid())
return false;
Target *target = m_exe_ctx.GetTargetPtr();
uint8_t bytebuf[4];
Error error;
const bool prefer_file_cache = true;
if (target->ReadMemory (func.GetBaseAddress(), prefer_file_cache, bytebuf,
sizeof (bytebuf), error) == static_cast<size_t>(-1))
return false;
uint8_t i386_prologue[] = {0x55, 0x89, 0xe5};
uint8_t x86_64_prologue[] = {0x55, 0x48, 0x89, 0xe5};
int prologue_size;
if (memcmp (bytebuf, i386_prologue, sizeof (i386_prologue)) == 0)
{
prologue_size = sizeof (i386_prologue);
}
else if (memcmp (bytebuf, x86_64_prologue, sizeof (x86_64_prologue)) == 0)
{
prologue_size = sizeof (x86_64_prologue);
}
else
{
return false;
}
pc_reginfo.SetAtCFAPlusOffset (-m_wordsize);
row->SetRegisterInfo (m_lldb_ip_regnum, pc_reginfo);
sp_reginfo.SetIsCFAPlusOffset (0);
row->SetRegisterInfo (m_lldb_sp_regnum, sp_reginfo);
// Zero instructions into the function
row->SetCFARegister (m_lldb_sp_regnum);
row->SetCFAOffset (m_wordsize);
row->SetOffset (0);
unwind_plan.AppendRow (row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
// push %rbp has executed - stack moved, rbp now saved
row->SetCFAOffset (2 * m_wordsize);
fp_reginfo.SetAtCFAPlusOffset (2 * -m_wordsize);
row->SetRegisterInfo (m_lldb_fp_regnum, fp_reginfo);
row->SetOffset (1);
unwind_plan.AppendRow (row);
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
// mov %rsp, %rbp has executed
row->SetCFARegister (m_lldb_fp_regnum);
row->SetCFAOffset (2 * m_wordsize);
row->SetOffset (prologue_size); /// 3 or 4 bytes depending on arch
unwind_plan.AppendRow (row);
newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset(newrow);
unwind_plan.SetPlanValidAddressRange (func);
unwind_plan.SetSourceName ("fast unwind assembly profiling");
unwind_plan.SetSourcedFromCompiler (eLazyBoolNo);
unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
return true;
}
bool
AssemblyParse_x86::find_first_non_prologue_insn (Address &address)
{
m_cur_insn = m_func_bounds.GetBaseAddress ();
if (!m_cur_insn.IsValid())
{
return false;
}
const bool prefer_file_cache = true;
Target *target = m_exe_ctx.GetTargetPtr();
while (m_func_bounds.ContainsFileAddress (m_cur_insn))
{
Error error;
int insn_len, offset, regno;
if (!instruction_length (m_cur_insn, insn_len) || insn_len > kMaxInstructionByteSize || insn_len == 0)
{
// An error parsing the instruction, i.e. probably data/garbage - stop scanning
break;
}
if (target->ReadMemory (m_cur_insn, prefer_file_cache, m_cur_insn_bytes,
insn_len, error) == static_cast<size_t>(-1))
{
// Error reading the instruction out of the file, stop scanning
break;
}
if (push_rbp_pattern_p () || mov_rsp_rbp_pattern_p () || sub_rsp_pattern_p (offset)
|| push_reg_p (regno) || mov_reg_to_local_stack_frame_p (regno, offset))
{
m_cur_insn.SetOffset (m_cur_insn.GetOffset() + insn_len);
continue;
}
// Unknown non-prologue instruction - stop scanning
break;
}
address = m_cur_insn;
return true;
}
//-----------------------------------------------------------------------------------------------
// UnwindAssemblyParser_x86 method definitions
//-----------------------------------------------------------------------------------------------
UnwindAssembly_x86::UnwindAssembly_x86 (const ArchSpec &arch, int cpu) :
lldb_private::UnwindAssembly(arch),
m_cpu(cpu),
m_arch(arch)
{
}
UnwindAssembly_x86::~UnwindAssembly_x86 ()
{
}
bool
UnwindAssembly_x86::GetNonCallSiteUnwindPlanFromAssembly (AddressRange& func, Thread& thread, UnwindPlan& unwind_plan)
{
ExecutionContext exe_ctx (thread.shared_from_this());
AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
return asm_parse.get_non_call_site_unwind_plan (unwind_plan);
}
bool
UnwindAssembly_x86::AugmentUnwindPlanFromCallSite (AddressRange& func, Thread& thread, UnwindPlan& unwind_plan)
{
ExecutionContext exe_ctx (thread.shared_from_this());
AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
return asm_parse.augment_unwind_plan_from_call_site (func, unwind_plan);
}
bool
UnwindAssembly_x86::GetFastUnwindPlan (AddressRange& func, Thread& thread, UnwindPlan &unwind_plan)
{
ExecutionContext exe_ctx (thread.shared_from_this());
AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
return asm_parse.get_fast_unwind_plan (func, unwind_plan);
}
bool
UnwindAssembly_x86::FirstNonPrologueInsn (AddressRange& func, const ExecutionContext &exe_ctx, Address& first_non_prologue_insn)
{
AssemblyParse_x86 asm_parse(exe_ctx, m_cpu, m_arch, func);
return asm_parse.find_first_non_prologue_insn (first_non_prologue_insn);
}
UnwindAssembly *
UnwindAssembly_x86::CreateInstance (const ArchSpec &arch)
{
const llvm::Triple::ArchType cpu = arch.GetMachine ();
if (cpu == llvm::Triple::x86)
return new UnwindAssembly_x86 (arch, k_i386);
else if (cpu == llvm::Triple::x86_64)
return new UnwindAssembly_x86 (arch, k_x86_64);
return NULL;
}
//------------------------------------------------------------------
// PluginInterface protocol in UnwindAssemblyParser_x86
//------------------------------------------------------------------
ConstString
UnwindAssembly_x86::GetPluginName()
{
return GetPluginNameStatic();
}
uint32_t
UnwindAssembly_x86::GetPluginVersion()
{
return 1;
}
void
UnwindAssembly_x86::Initialize()
{
PluginManager::RegisterPlugin (GetPluginNameStatic(),
GetPluginDescriptionStatic(),
CreateInstance);
}
void
UnwindAssembly_x86::Terminate()
{
PluginManager::UnregisterPlugin (CreateInstance);
}
lldb_private::ConstString
UnwindAssembly_x86::GetPluginNameStatic()
{
static ConstString g_name("x86");
return g_name;
}
const char *
UnwindAssembly_x86::GetPluginDescriptionStatic()
{
return "i386 and x86_64 assembly language profiler plugin.";
}
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