SMPFunction.cpp

//
// SMPFunction.cpp
//
// This module performs the fundamental data flow analyses needed for the
//   SMP project (Software Memory Protection) at the function level.
//

#include <utility>
#include <list>
#include <set>
#include <vector>
#include <algorithm>

#include <cstring>
#include <cstdlib>

#include <pro.h>
#include <assert.h>
#include <ida.hpp>
#include <idp.hpp>
#include <auto.hpp>
#include <bytes.hpp>
#include <funcs.hpp>
#include <allins.hpp>
#include <intel.hpp>
#include <name.hpp>

#include "SMPDataFlowAnalysis.h"
#include "SMPStaticAnalyzer.h"
#include "SMPFunction.h"
#include "SMPBasicBlock.h"
#include "SMPInstr.h"

// Set to 1 for debugging output
#define SMP_DEBUG 1
#define SMP_DEBUG2 0   // verbose
#define SMP_DEBUG3 0   // verbose
#define SMP_DEBUG_CONTROLFLOW 0  // tells what processing stage is entered
#define SMP_DEBUG_XOR 0
#define SMP_DEBUG_CHUNKS 1  // tracking down tail chunks for functions
#define SMP_DEBUG_FRAMEFIXUP 0
#define SMP_DEBUG_DATAFLOW 0
#define SMP_DEBUG_TYPE_INFERENCE 0
#define SMP_DEBUG_STACK_GRANULARITY 0
#define SMP_DEBUG_FUNC 0
#define SMP_VERBOSE_DEBUG_FUNC 0
#define SMP_DEBUG_BUILD_RTL 1   // leave this on; serious errors reported
#define SMP_DEBUG_UNINITIALIZED_SSA_NAMES 1

// Compute LVA/SSA or not? Turn it off for NICECAP demo on 31-JAN-2008
#define SMP_COMPUTE_LVA_SSA 1

// Compute fine-grained stack boundaries?
#define SMP_COMPUTE_STACK_GRANULARITY 1

// Insert a floating no-op instruction at top of each function to hold SSA DEFs
//  of LiveIn names?
#define SMP_USE_SSA_FNOP_MARKER 1

// Use conditional type propagation on phi functions
#define SMP_CONDITIONAL_TYPE_PROPAGATION 0

// Basic block number 0 is the top of the CFG lattice.
#define SMP_TOP_BLOCK 0 

// Set SharedTailChunks to TRUE for entire printf family
//  After we restructure the parent/tail structure of the database, this
//  will go away.
#define KLUDGE_VFPRINTF_FAMILY 1

// Used for binary search by function number in SMPStaticAnalyzer.cpp
//  to trigger debugging output and find which instruction in which
//  function is causing a crash.
bool SMPBinaryDebug = false;


// *****************************************************************
// Class SMPFunction
// *****************************************************************

// Constructor
SMPFunction::SMPFunction(func_t *Info) {
	this->FuncInfo = *Info;
	this->IndirectCalls = false;
	this->IndirectJumps = false;
	this->UnresolvedIndirectJumps = false;
	this->SharedChunks = false;
	this->CallsAlloca = false;
	this->BuiltRTLs = false;
	this->OutgoingArgsSize = 0;
	this->BlockCount = 0;
	this->LocalVarTable.clear();
	this->StackFrameMap.clear();
	this->DirectCallTargets.clear();
	this->ReturnAddrStatus = FUNC_UNKNOWN;
	this->Blocks.clear();
	this->Instrs.clear();
	this->GlobalNames.clear();
	return;
}

// Reset the Processed flags in all blocks to false.
void SMPFunction::ResetProcessedBlocks(void) {
	list<SMPBasicBlock>::iterator CurrBlock;
	for (CurrBlock = this->Blocks.begin(); CurrBlock != this->Blocks.end(); ++CurrBlock) {
		CurrBlock->SetProcessed(false);
	}
	return;
} // end of SMPFunction::ResetProcessedBlocks()

// Figure out the different regions of the stack frame, and find the
//  instructions that allocate and deallocate the local variables space
//  on the stack frame.
// The stack frame info will be used to emit stack
//  annotations when Analyze() reaches the stack allocation
//  instruction that sets aside space for local vars.
// Set the address of the instruction at which these
//  annotations should be emitted. This should normally
//  be an instruction such as:  sub esp,48
//  However, for a function with no local variables at all,
//  we will need to determine which instruction should be
//  considered to be the final instruction of the function
//  prologue and return its address.
// Likewise, we find the stack deallocating instruction in
//  the function epilogue.
void SMPFunction::SetStackFrameInfo(void) {
	bool FoundAllocInstr = false;
	bool FoundDeallocInstr = false;
	bool DebugFlag = false;
#if SMP_DEBUG_FRAMEFIXUP
	DebugFlag |= (0 == strcmp(".init_proc", this->GetFuncName()));
#endif

	// The sizes of the three regions of the stack frame other than the
	//  return address are stored in the function structure.
	this->LocalVarsSize = this->FuncInfo.frsize;
	this->CalleeSavedRegsSize = this->FuncInfo.frregs;
	this->IncomingArgsSize = this->FuncInfo.argsize;

	// The return address size can be obtained in a machine independent
	//  way by calling get_frame_retsize(). 
	this->RetAddrSize = get_frame_retsize(&(this->FuncInfo));

	// IDA Pro has trouble with functions that do not have any local
	//  variables. Unfortunately, the C library has plenty of these
	//  functions. IDA usually claims that frregs is zero and frsize
	//  is N, when the values should have been reversed. We can attempt
	//  to detect this and fix it.
	bool FrameInfoFixed = this->MDFixFrameInfo();
#if SMP_DEBUG_CONTROLFLOW
	msg("Returned from MDFixFrameInfo()\n");
#endif
#if SMP_DEBUG_FRAMEFIXUP
	if (FrameInfoFixed) {
		msg("Fixed stack frame size info: %s\n", this->FuncName);
		SMPBasicBlock CurrBlock = this->Blocks.front();
		msg("First basic block:\n");
		for (list<list<SMPInstr>::iterator>::iterator CurrInstr = CurrBlock.GetFirstInstr();
			CurrInstr != CurrBlock.GetLastInstr();
			++CurrInstr) {
			msg("%s\n", (*CurrInstr)->GetDisasm());
		}
	}
#endif

	// Now, if LocalVarsSize is not zero, we need to find the instruction
	//  in the function prologue that allocates space on the stack for
	//  local vars. This code could be made more robust in the future
	//  by matching LocalVarsSize to the immediate value in the allocation
	//  instruction. However, IDA Pro is sometimes a little off on this
	//  number. **!!**
	if (0 < this->LocalVarsSize) {
		if (DebugFlag) msg("Searching for alloc and dealloc\n");
		for (list<SMPInstr>::iterator CurrInstr = this->Instrs.begin();
			CurrInstr != this->Instrs.end();
			++CurrInstr) {

#if SMP_USE_SSA_FNOP_MARKER
			if (this->Instrs.begin() == CurrInstr)
				continue;  // skip marker instruction
#endif

			ea_t addr = CurrInstr->GetAddr();

			// Keep the most recent instruction in the DeallocInstr
			//  in case we reach the return without seeing a dealloc.
			if (!FoundDeallocInstr) {
				this->LocalVarsDeallocInstr = addr;
			}

			if (!FoundAllocInstr
				&& CurrInstr->MDIsFrameAllocInstr()) {
#if SMP_DEBUG_CONTROLFLOW
				msg("Returned from MDIsFrameAllocInstr()\n");
#endif
				this->LocalVarsAllocInstr = addr;
				FoundAllocInstr = true;
				if (DebugFlag) msg("Found alloc: %s\n", CurrInstr->GetDisasm());
				// As soon as we have found the local vars allocation,
				//  we can try to fix incorrect sets of UseFP by IDA.
				// NOTE: We might want to extend this in the future to
				//  handle functions that have no locals.  **!!**
				bool FixedUseFP = MDFixUseFP();
#if SMP_DEBUG_CONTROLFLOW
				msg("Returned from MDFixUseFP()\n");
#endif
#if SMP_DEBUG_FRAMEFIXUP
				if (FixedUseFP) {
					msg("Fixed UseFP in %s\n", this->FuncName);
				}
#endif
			}
			else if (FoundAllocInstr) {
				// We can now start searching for the DeallocInstr.
				if (CurrInstr->MDIsFrameDeallocInstr(UseFP, this->LocalVarsSize)) {
					// Keep saving the most recent addr that looks
					//  like the DeallocInstr until we reach the
					//  end of the function. Last one to look like
					//  it is used as the DeallocInstr.
#if SMP_DEBUG_CONTROLFLOW
					msg("Returned from MDIsFrameDeallocInstr()\n");
#endif
					this->LocalVarsDeallocInstr = addr;
					FoundDeallocInstr = true;
				}
				else {
					if (DebugFlag) msg("Not dealloc: %s\n", CurrInstr->GetDisasm());
				}
			}
		} // end for (list<SMPInstr>::iterator CurrInstr ... )
		if (!FoundAllocInstr) {
			// Could not find the frame allocating instruction.  Bad.
			// See if we can find the point at which the stack allocation reaches
			//  a total of FuncInfo.frsize+frregs, regardless of whether it happened by push
			//  instructions or some other means.
			this->LocalVarsAllocInstr = this->FindAllocPoint(this->FuncInfo.frsize + this->FuncInfo.frregs);
#if SMP_DEBUG_CONTROLFLOW
			msg("Returned from FindAllocPoint()\n");
#endif
#if SMP_DEBUG_FRAMEFIXUP
			if (BADADDR == this->LocalVarsAllocInstr) {
				msg("ERROR: Could not find stack frame allocation in %s\n",
					FuncName);
				msg("LocalVarsSize: %d  SavedRegsSize: %d ArgsSize: %d\n",
					LocalVarsSize, CalleeSavedRegsSize, IncomingArgsSize);
			}
			else {
				msg("FindAllocPoint found %x for function %s\n",
					this->LocalVarsAllocInstr, this->GetFuncName());
			}
#endif
		}
#if SMP_DEBUG_FRAMEFIXUP
		if (!FoundDeallocInstr) {
			// Could not find the frame deallocating instruction.  Bad.
			// Emit diagnostic and use the last instruction in the
			// function.
			msg("ERROR: Could not find stack frame deallocation in %s\n",
				FuncName);
		}
#endif
	}
	// else LocalVarsSize was zero, meaning that we need to search 
	//  for the end of the function prologue code and emit stack frame
	//  annotations from that address (i.e. this method returns that
	//  address). We will approximate this by finding the end of the
	//  sequence of PUSH instructions at the beginning of the function.
	//  The last PUSH instruction should be the last callee-save-reg
	//  instruction. We can make this more robust in the future by
	//  making sure that we do not count a PUSH of anything other than
	//  a register. **!!**
	// NOTE: 2nd prologue instr is usually mov ebp,esp
	// THE ASSUMPTION THAT WE HAVE ONLY PUSH INSTRUCTIONS BEFORE
	// THE ALLOCATING INSTR IS ONLY TRUE WHEN LOCALVARSSIZE == 0;
	else {
		ea_t SaveAddr = this->FuncInfo.startEA;
		for (list<SMPInstr>::iterator CurrInstr = this->Instrs.begin();
			CurrInstr != this->Instrs.end();
			++CurrInstr) {
#if SMP_USE_SSA_FNOP_MARKER
			if (this->Instrs.begin() == CurrInstr)
				continue;  // skip marker instruction
#endif

			insn_t CurrCmd = CurrInstr->GetCmd();
			ea_t addr = CurrInstr->GetAddr();
			if (CurrCmd.itype == NN_push)
				SaveAddr = addr;
			else
				break;
		}
		this->LocalVarsAllocInstr = SaveAddr;
		this->LocalVarsDeallocInstr = 0;
	} // end if (LocalVarsSize > 0) ... else ...

#if 0
	// Now we need to do the corresponding operations from the
	//  end of the function to find the DeallocInstr in the
	//  function epilogue. Because there is no addition to the
	//  stack pointer to deallocate the local vars region, the
	//  function epilogue will consist of (optional) pops of
	//  callee-saved regs, followed by the return instruction.
	//  Working backwards, we should find a return and then 
	//  stop when we do not find any more pops.
	if (0 >= LocalVarsSize) {
		this->LocalVarsDeallocInstr = NULL;
	}
	else {
		SaveAddr = this->FuncInfo.endEA - 1;
		bool FoundRet = false;
		do {
			ea_t addr = get_item_head(SaveAddr);
			flags_t InstrFlags = getFlags(addr);
			if (isCode(addr) && isHead(addr)) {
				ua_ana0(addr);
				if (!FoundRet) { // Just starting out.
					if (MDIsReturnInstr(cmd)) {
						FoundRet = true;
						SaveAddr = addr - 1;
					}
					else {
						msg("ERROR: Last instruction not a return.\n");
					}
				}
				else { // Should be 0 or more POPs before the return.
					if (MDIsPopInstr(cmd)) {
						SaveAddr = addr - 1;
					}
					else if (FrameAllocInstr(cmd, this->LocalVarsSize)) {
						this->LocalVarsDeallocInstr = addr;
					}
					else {
						msg("ERROR: Frame deallocation not prior to POPs.\n");
						this->LocalVarsDeallocInstr = SaveAddr + 1;
					}
				} // end if (!FoundRet) ... else ...
			}
			else {
				--SaveAddr;
			} // end if (isCode(addr) && isHead(addr))
		} while (NULL == this->LocalVarsDeallocInstr);
	} // end if (0 >= this->LocalVarsSize)
#endif // 0

	this->CallsAlloca = this->FindAlloca();

#if SMP_COMPUTE_STACK_GRANULARITY
	// Now, find the boundaries between local variables.
	this->BuildLocalVarTable();
#endif

	return;
} // end of SMPFunction::SetStackFrameInfo()

// IDA Pro defines the sizes of regions in the stack frame in a way
//  that suits its purposes but not ours. The frsize field of the func_info_t
//  structure measures the distance between the stack pointer and the
//  frame pointer (ESP and EBP in the x86). This region includes some
//  of the callee-saved registers. So, the frregs field only includes
//  the callee-saved registers that are above the frame pointer.
//  x86 standard prologue on gcc/linux:
//    push ebp      ; save old frame pointer
//    mov ebp,esp   ; new frame pointer = current stack pointer
//    push esi      ; callee save reg
//    push edi      ; callee save reg
//    sub esp,34h   ; allocate 52 bytes for local variables
//
//  Notice that EBP acquires its final frame pointer value AFTER the
//  old EBP has been pushed. This means that, of the three callee saved
//  registers, one is above where EBP points and two are below.
//  IDA Pro is concerned with generating readable addressing expressions
//  for items on the stack. None of the callee-saved regs will ever
//  be addressed in the function; they will be dormant until they are popped
//  off the stack in the function epilogue. In order to create readable
//  disassembled code, IDA defines named constant offsets for locals. These
//  offsets are negative values (x86 stack grows downward from EBP toward
//  ESP). When ESP_relative addressing occurs, IDA converts a statement:
//    mov eax,[esp+12]
//  into the statement:
//    mov eax,[esp+3Ch+var_30]
//  Here, 3Ch == 60 decimal is the distance between ESP and EBP, and
//  var_30 is defined to ahve the value -30h == -48 decimal. So, the
//  "frame size" in IDA Pro is 60 bytes, and a certain local can be
//  addressed in ESP-relative manner as shown, or as [ebp+var_30] for
//  EBP-relative addressing. The interactive IDA user can then edit
//  the name var_30 to something mnemonic, such as "virus_size", and IDA
//  will replace all occurrences with the new name, so that code references
//  automatically become [ebp+virus_size]. As the user proceeds
//  interactively, he eventually produces very understandable code.
// This all makes sense for producing readable assembly text. However,
//  our analyses have a compiler perspective as well as a memory access
//  defense perspective. SMP distinguishes between callee saved regs,
//  which should not be overwritten in the function body, and local
//  variables, which can be written. We view the stack frame in logical
//  pieces: here are the saved regs, here are the locals, here is the
//  return address, etc. We don't care which direction from EBP the
//  callee-saved registers lie; we don't want to lump them in with the
//  local variables. We also don't like the fact that IDA Pro will take
//  the function prologue code shown above and declare frregs=4 and
//  frsize=60, because frsize no longer matches the stack allocation
//  statement sub esp,34h == sub esp,52. We prefer frsize=52 and frregs=12.
// So, the task of this function is to fix these stack sizes in our
//  private data members for the function, while leaving the IDA database
//  alone because IDA needs to maintain its own definitions of these
//  variables.
// Fixing means we will update the data members LocalVarsSize and
//  CalleeSavedRegsSize.
// NOTE: This function is both machine dependent and platform dependent.
//  The prologue and epilogue code generated by gcc-linux is as discussed
//  above, while on Visual Studio and other Windows x86 compilers, the
//  saving of registers other than EBP happens AFTER local stack allocation.
//  A Windows version of the function would expect to see the pushing
//  of ESI and EDI AFTER the sub esp,34h statement.
bool SMPFunction::MDFixFrameInfo(void) {
	int SavedRegsSize = 0;
	int OtherPushesSize = 0;  // besides callee-saved regs
	int NewLocalsSize = 0;
	int OldFrameTotal = this->CalleeSavedRegsSize + this->LocalVarsSize;
	bool Changed = false;
	bool DebugFlag = (0 == strcmp("__libc_csu_init", this->GetFuncName()));

	// Iterate through the first basic block in the function. If we find
	//  a frame allocating Instr in it, then we have local vars. If not,
	//  we don't, and LocalVarsSize should have been zero. Count the callee
	//  register saves leading up to the local allocation. Set data members
	//  according to what we found if the values of the data members would
	//  change.
	SMPBasicBlock CurrBlock = this->Blocks.front();
	for (list<list<SMPInstr>::iterator>::iterator CurrIter = CurrBlock.GetFirstInstr();
		CurrIter != CurrBlock.GetLastInstr();
		++CurrIter) {
#if SMP_USE_SSA_FNOP_MARKER
		if (CurrBlock.GetFirstInstr() == CurrIter)
			continue;  // skip marker instruction
#endif

		list<SMPInstr>::iterator CurrInstr = *CurrIter;
		if (CurrInstr->MDIsPushInstr()) {
			// We will make the gcc-linux assumption that a PUSH in
			//  the first basic block, prior to the stack allocating
			//  instruction, is a callee register save. To make this
			//  more robust, we ensure that the register is from
			//  the callee saved group of registers, and that it has
			//  not been defined thus far in the function (else it might
			//  be a push of an outgoing argument to a call that happens
			//  in the first block when there are no locals). **!!!!**
			if (CurrInstr->MDUsesCalleeSavedReg()
				&& !CurrInstr->HasSourceMemoryOperand()) {
				SavedRegsSize += 4; // **!!** should check the size
				if (DebugFlag) msg("libc_csu_init SavedRegsSize: %d  %s\n", SavedRegsSize,
					CurrInstr->GetDisasm());
			}
			else {
				// Pushes of outgoing args can be scheduled so that
				//  they are mixed with the pushes of callee saved regs.
				OtherPushesSize += 4;
				if (DebugFlag) msg("libc_csu_init OtherPushesSize: %d  %s\n", OtherPushesSize,
					CurrInstr->GetDisasm());
			}
		}
		else if (CurrInstr->MDIsFrameAllocInstr()) {
			if (DebugFlag) msg("libc_csu_init allocinstr: %s\n", CurrInstr->GetDisasm());
			SavedRegsSize += OtherPushesSize;
			// Get the size being allocated.
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInstr->GetFirstUse(); CurrUse != CurrInstr->GetLastUse(); ++CurrUse) {
				// Find the immediate operand.
				if (o_imm == CurrUse->GetOp().type) {
					// Get its value into LocalVarsSize.
					long AllocValue = (signed long) CurrUse->GetOp().value;
					// One compiler might have sub esp,24 and another
					//  might have add esp,-24. Take the absolute value.
					if (0 > AllocValue)
						AllocValue = -AllocValue;
					if (AllocValue != (long) this->LocalVarsSize) {
						Changed = true;
#if SMP_DEBUG_FRAMEFIXUP
						if (AllocValue + SavedRegsSize != OldFrameTotal)
							msg("Total frame size changed: %s\n", this->FuncName);
#endif
						this->LocalVarsSize = (asize_t) AllocValue;
						this->CalleeSavedRegsSize = (ushort) SavedRegsSize;
						NewLocalsSize = this->LocalVarsSize;
					}
					else { // Old value was correct; no change.
						NewLocalsSize = this->LocalVarsSize;
						if (SavedRegsSize != this->CalleeSavedRegsSize) {
							this->CalleeSavedRegsSize = (ushort) SavedRegsSize;
							Changed = true;
#if SMP_DEBUG_FRAMEFIXUP
							msg("Only callee regs size changed: %s\n", this->FuncName);
#endif
						}
					}
				} // end if (o_imm == ...)
			} // end for all uses
			break; // After frame allocation instr, we are done
		} // end if (push) .. elsif frame allocating instr
	} // end for all instructions in the first basic block

	// If we did not find an allocating instruction, see if it would keep
	//  the total size the same to set LocalVarsSize to 0 and to set
	//  CalleeSavedRegsSize to SavedRegsSize. If so, do it. If not, we
	//  might be better off to leave the numbers alone.
	if (!Changed && (NewLocalsSize == 0)) {
		if (DebugFlag) msg("libc_csu_init OldFrameTotal: %d  %s\n", OldFrameTotal);
		if (OldFrameTotal == SavedRegsSize) {
			this->CalleeSavedRegsSize = SavedRegsSize;
			this->LocalVarsSize = 0;
			Changed = true;
		}
#if SMP_DEBUG_FRAMEFIXUP
		else {
			msg("Could not update frame sizes: %s\n", this->FuncName);
		}
#endif
	}

#if SMP_DEBUG_FRAMEFIXUP
	if ((0 < OtherPushesSize) && (0 < NewLocalsSize))
		msg("Extra pushes found of size %d in %s\n", OtherPushesSize,
			this->FuncName);
#endif

	return Changed;
} // end of SMPFunction::MDFixFrameInfo()

// Some functions have difficult to find stack allocations. For example, in some
//  version of glibc, strpbrk() zeroes out register ECX and then pushes it more than
//  100 times in order to allocate zero-ed out local vars space for a character translation
//  table. We will use the stack pointer analysis of IDA to find out if there is a point
//  in the first basic block at which the stack pointer reaches the allocation total
//  that IDA is expecting for the local vars region.
// If so, we return the address of the instruction at which ESP reaches its value, else
//  we return BADADDR.
ea_t SMPFunction::FindAllocPoint(asize_t OriginalLocSize) {
	bool DebugFlag = (0 == strcmp("_dl_runtime_resolve", this->GetFuncName()));
	sval_t TargetSize = - ((sval_t) OriginalLocSize);  // negate; stack grows down 

#if SMP_DEBUG_FRAMEFIXUP
	if (DebugFlag)
		msg("%s OriginalLocSize: %d\n", this->GetFuncName(), OriginalLocSize);
#endif

	if (this->AnalyzedSP) {
		// Limit our analysis to the first basic block in the function.
		list<SMPInstr>::iterator CurrInstr;
		for (CurrInstr = this->Instrs.begin(); CurrInstr != this->Instrs.end();	++CurrInstr) {
#if SMP_USE_SSA_FNOP_MARKER
			if (this->Instrs.begin() == CurrInstr)
				continue;  // skip marker instruction
#endif

			ea_t addr = CurrInstr->GetAddr();
			// get_spd() returns a cumulative delta of ESP
			sval_t sp_delta = get_spd(&(this->FuncInfo), addr);
#if SMP_DEBUG_FRAMEFIXUP
			if (DebugFlag)
				msg("%s delta: %d at %x\n", this->GetFuncName(), sp_delta, addr);
#endif
			if (sp_delta == TargetSize) { // <= instead of == here?  **!!**
				// Previous instruction hit the frame size.
				if (CurrInstr == this->Instrs.begin()) {
					return BADADDR;  // cannot back up from first instruction
				}
				else {
					ea_t PrevAddr = (--CurrInstr)->GetAddr();
#if SMP_USE_SSA_FNOP_MARKER
					if (this->Instrs.begin()->GetAddr() == PrevAddr)
						return BADADDR;  // don't return marker instruction
					else
						return PrevAddr;
#else
					return PrevAddr;
#endif
				}
			}
			if (CurrInstr->IsLastInBlock()) {
				// It could be that the current instruction will cause the stack pointer
				//  delta to reach the TargetSize. sp_delta is not updated until after the
				//  current instruction, so we need to look ahead one instruction if the
				//  current block falls through. On the other hand, if the current block
				//  ends with a jump or return, we cannot hit TargetSize.
				if (CurrInstr->IsBasicBlockTerminator())
					return BADADDR;
				list<SMPInstr>::iterator NextInstr = CurrInstr;
				++NextInstr;
				if (NextInstr == this->Instrs.end())
					return BADADDR;
				sp_delta = get_spd(&(this->FuncInfo), NextInstr->GetAddr());
				if (sp_delta == TargetSize) {
					// CurrInstr will cause stack pointer delta to hit TargetSize.
					return addr;
				}
				else {
					return BADADDR;
				}
			} // end if LastInBlock
		} // end for all instructions
	} // end if (this->AnalyzedSP)
#if SMP_DEBUG_FRAMEFIXUP
	else {
		msg("AnalyzedSP is false for %s\n", this->GetFuncName());
	}
#endif
	return BADADDR;
} // end of SMPFunction::FindAllocPoint()

// IDA Pro is sometimes confused by a function that uses the frame pointer
//  register for other purposes. For the x86, a function that uses EBP
//  as a frame pointer would begin with: push ebp; mov ebp,esp to save
//  the old value of EBP and give it a new value as a frame pointer. The
//  allocation of local variable space would have to come AFTER the move
//  instruction. A function that begins: push ebp; push esi; sub esp,24
//  is obviously not using EBP as a frame pointer. IDA is apparently
//  confused by the push ebp instruction being the first instruction
//  in the function. We will reset UseFP to false in this case.
// The inverse problem happens with a function that begins with instructions
//  other than push ebp; mov ebp,esp; ... etc. but eventually has those
//  instructions in the first basic block. For example, a C compiler generates
//  for the first block of main():
//    lea ecx,[esp+arg0]
//    and esp, 0xfffffff0
//    push dword ptr [ecx-4]
//    push ebp
//    mov ebp,esp
//    push ecx
//    sub esp,<framesize>
//
//  This function is obviously using EBP as a frame pointer, but IDA Pro marks
//  the function as not using a frame pointer. We will reset UseFP to true in
//  this case.
// NOTE: This logic should work for both Linux and Windows x86 prologues.
bool SMPFunction::MDFixUseFP(void) {
	list<SMPInstr>::iterator CurrInstr = this->Instrs.begin();
	ea_t addr = CurrInstr->GetAddr();

#if SMP_USE_SSA_FNOP_MARKER
	if (this->Instrs.begin() == CurrInstr)
		++CurrInstr;  // skip marker instruction
#endif

	if (!(this->UseFP)) {
		// See if we can detect the instruction "push ebp" followed by the instruction
		//  "mov ebp,esp" in the first basic block. The instructions do not have to be
		//  consecutive. If we find them, we will reset UseFP to true.
		bool FirstBlockProcessed = false;
		bool EBPSaved = false;
		bool ESPintoEBP = false;
		do {
			FirstBlockProcessed = CurrInstr->IsLastInBlock();
			if (!EBPSaved) { // still looking for "push ebp"
				if (CurrInstr->MDIsPushInstr() && CurrInstr->GetCmd().Operands[0].is_reg(R_bp)) {
					EBPSaved = true;
				}
			}
			else if (!ESPintoEBP) { // found "push ebp", looking for "mov ebp,esp"
				insn_t CurrCmd = CurrInstr->GetCmd();
				if ((CurrCmd.itype == NN_mov) 
					&& (CurrInstr->GetFirstDef()->GetOp().is_reg(R_bp))
					&& (CurrInstr->GetFirstUse()->GetOp().is_reg(R_sp))) {
					ESPintoEBP = true;
					FirstBlockProcessed = true; // exit loop
				}
			}
			++CurrInstr;
			addr = CurrInstr->GetAddr();
			// We must get EBP set to its frame pointer value before we reach the
			//  local frame allocation instruction (i.e. the subtraction of locals space
			//   from the stack pointer).
			FirstBlockProcessed |= (addr >= this->LocalVarsAllocInstr);
		} while (!FirstBlockProcessed);
		// If we found ESPintoEBP, we also found EBPSaved first, and we need to change
		//  this->UseFP to true and return true. Otherwise, return false.
		this->UseFP = ESPintoEBP;
		return ESPintoEBP;
	} // end if (!(this->UseFP))

	// At this point, this->UseFP must have been true on entry to this method and we will
	//  check whether it should be reset to false.
	while (addr < this->LocalVarsAllocInstr) {
		set<DefOrUse, LessDefUse>::iterator CurrDef = CurrInstr->GetFirstDef();
		while (CurrDef != CurrInstr->GetLastDef()) {
			if (CurrDef->GetOp().is_reg(R_bp))
				return false; // EBP got set before locals were allocated
			++CurrDef;
		}
		++CurrInstr;
		addr = CurrInstr->GetAddr();
	}
	// If we found no defs of the frame pointer before the local vars
	//  allocation, then the frame pointer register is not being used
	//  as a frame pointer, just as a general callee-saved register.
	this->UseFP = false;
	return true;
} // end of SMPFunction::MDFixUseFP()

// Determine local variable boundaries in the stack frame.
void SMPFunction::BuildLocalVarTable(void) {
	// Currently we just use the info that IDA Pro has inferred from the direct
	//  addressing of stack locations.
	this->SemiNaiveLocalVarID();
	return;
} // end of SMPFunction::BuildLocalVarTable()

// Use the local variable offset list from IDA's stack frame structure to compute
//  the table of local variable boundaries.
void SMPFunction::SemiNaiveLocalVarID(void) {
	// NOTE: We use IDA Pro's offsets from this->FuncInfo (e.g. frsize) and NOT
	//  our own corrected values in our private data members. The offsets we
	//  read from the stack frame structure returned by get_frame() are consistent
	//  with other IDA Pro values, not with our corrected values.
	bool DebugFlag = false;
#if SMP_DEBUG_STACK_GRANULARITY
	DebugFlag |= (0 == strcmp("qSort3", this->GetFuncName()));
#endif
	func_t *FuncPtr = get_func(this->FuncInfo.startEA);
	if (NULL == FuncPtr) {
		msg("ERROR in SMPFunction::SemiNaiveLocalVarID; no func ptr\n");
	}
	assert(NULL != FuncPtr);
	struc_t *StackFrame = get_frame(FuncPtr);

	if (NULL == StackFrame) {
		msg("WARNING: No stack frame info from get_frame for %s\n", this->GetFuncName());
		return;
	}

	member_t *Member = StackFrame->members;
	for (size_t i = 0; i < StackFrame->memqty; ++i, ++Member) {
		long offset;
		char MemberName[MAXSTR] = {'\0'};
		if (NULL == Member) {
			msg("NULL stack frame member pointer in %s\n", this->GetFuncName());
			break;
		}
		get_member_name(Member->id, MemberName, MAXSTR - 1);
		if (MemberName == NULL) {
#if SMP_DEBUG_STACK_GRANULARITY
			msg("NULL stack frame member in %s\n", this->GetFuncName());
#endif
			continue;
		}
		offset = Member->soff;
		if (MemberName[0] == ' ') {
#if SMP_DEBUG_STACK_GRANULARITY
			msg("NULL stack frame name at offset %d in %s\n", offset, this->GetFuncName());
#endif
			MemberName[1] = '\0';
		}
		if (DebugFlag) {
			msg("%s local var %s at offset %d\n", this->GetFuncName(), MemberName, offset);
		}
		if (offset >= (long) this->LocalVarsSize)
			break;  // Stop after processing locals and outgoing args
#if 0
		// We want the offset from the stack pointer after local frame allocation.
		//  This subtraction would make it relative to the original stack pointer.
		offset -= this->FuncInfo.frsize;
#endif
		struct LocalVar TempLocal;
		TempLocal.offset = offset;
		TempLocal.size = -1; // compute later
		qstrncpy(TempLocal.VarName, MemberName, MAXSTR - 1);
		this->LocalVarTable.push_back(TempLocal);
	} // end for all stack frame members

	if (this->LocalVarTable.empty())
		return;

#if SMP_DEBUG_STACK_GRANULARITY
	msg("Computing %d local var sizes\n", this->LocalVarTable.size());
#endif
	// Now we want to fill in the size field for each local
	for (size_t VarIndex = 0; VarIndex < (this->LocalVarTable.size() - 1); ++VarIndex) {
		this->LocalVarTable[VarIndex].size = this->LocalVarTable[VarIndex + 1].offset
			- this->LocalVarTable[VarIndex].offset;
	}
#if SMP_DEBUG_STACK_GRANULARITY
	msg("Computing last local var size for frsize %d\n", this->FuncInfo.frsize);
#endif
	// Size of last local is total frsize minus savedregs in frame minus offset of last local
	if (this->LocalVarTable.size() > 0) {
		size_t SavedRegsSpace = 0; // portion of frsize that is saved regs, not locals.
		if (this->CalleeSavedRegsSize > this->FuncInfo.frregs) {
			// IDA Pro counts the save of EBP in frregs, but then EBP gets its new
			//  value and callee saved regs other than the old EBP push get counted
			//  in frsize rather than frregs. CalleeSavedRegsSize includes all saved
			//  regs on the stack, both above and below the current EBP offset.
			// NOTE: For windows, this has to be done differently, as callee saved regs
			//  happen at the bottom of the local frame, not the top.
#if 0
			SavedRegsSpace = this->CalleeSavedRegsSize - this->FuncInfo.frregs;
#else
			SavedRegsSpace = this->FuncInfo.frsize - this->LocalVarsSize;
#endif
		}
		this->LocalVarTable[this->LocalVarTable.size() - 1].size = this->FuncInfo.frsize
			- SavedRegsSpace - this->LocalVarTable[this->LocalVarTable.size() - 1].offset;
	}
	this->LocalVarOffsetLimit = this->LocalVarTable.back().offset 
		+ (adiff_t) this->LocalVarTable.back().size;
	assert(this->LocalVarOffsetLimit <= (adiff_t) this->FuncInfo.frsize);
	// Find out how many of the locals are really outgoing args.
	if (this->AnalyzedSP && !this->CallsAlloca && (BADADDR != this->LocalVarsAllocInstr)) {
		this->FindOutgoingArgsSize();
	}
	else {
		msg("FindOutgoingArgsSize not called for %s ", this->GetFuncName());
		msg("AnalyzedSP: %d CallsAlloca: %d LocalVarsAllocInstr: %x \n",
			this->AnalyzedSP, this->CallsAlloca, this->LocalVarsAllocInstr);
	}
	return;
} // end of SMPFunction::SemiNaiveLocalVarID()

// Determine how many bytes at the bottom of the stack frame (i.e. at bottom of
//  this->LocalVarsSize) are used for outgoing args. This is the case when the cdecl
//  calling convention is used, e.g. gcc/linux allocates local var space + out args space
//  in a single allocation and then writes outarg values directly to ESP+0, ESP+4, etc.
void SMPFunction::FindOutgoingArgsSize(void) {
	// Compute the lowest value reached by the stack pointer.
	list<SMPInstr>::iterator CurrInst;
	this->MinStackDelta = 20000; // Final value should be negative
	bool DebugFlag = false;
#if SMP_DEBUG_STACK_GRANULARITY
	DebugFlag = (0 == strcmp("simtest", this->GetFuncName()));
#endif
	for (CurrInst = this->Instrs.begin(); CurrInst != this->Instrs.end(); ++CurrInst) {
#if SMP_USE_SSA_FNOP_MARKER
		if (this->Instrs.begin() == CurrInst)
			continue;  // skip marker instruction
#endif

		ea_t addr = CurrInst->GetAddr();
		sval_t sp_delta = get_spd(&(this->FuncInfo), addr);
		if (sp_delta < this->MinStackDelta)
			this->MinStackDelta = sp_delta;
		if (addr == this->LocalVarsAllocInstr) {
			// Total stack pointer delta is sp_delta for the next instruction,
			//  because IDA updates the sp delta AFTER each instruction.
			list<SMPInstr>::iterator NextInst = CurrInst;
			++NextInst;
			sp_delta = get_spd(&(this->FuncInfo), NextInst->GetAddr());
			this->AllocPointDelta = sp_delta;
		}
	}
#if SMP_DEBUG_STACK_GRANULARITY
	msg("AllocPointDelta: %d MinStackDelta: %d\n", this->AllocPointDelta, this->MinStackDelta);
#endif
	assert(0 > this->MinStackDelta);

	// Allocate a vector of stack frame entries, one for each byte of the stack frame.
	//  This will be our memory map for analyzing stack usage.
	int limit = 0;
#if 1
	if (this->LocalVarOffsetLimit > 0)
		limit = this->LocalVarOffsetLimit;
#endif
	for (int i = this->MinStackDelta; i < limit; ++i) {
		struct StackFrameEntry TempEntry;
		TempEntry.VarPtr = NULL;
		TempEntry.offset = (long) i;
		TempEntry.Read = false;
		TempEntry.Written = false;
		TempEntry.AddressTaken = false;
		TempEntry.ESPRelativeAccess = false;
		TempEntry.EBPRelativeAccess = false;
		this->StackFrameMap.push_back(TempEntry);
	}

	// Fill in the VarPtr fields for each StackFrameMap entry.
	if (0 <= this->AllocPointDelta) {
		msg("FATAL ERROR: AllocPointDelta = %d in %s\n", this->AllocPointDelta, this->GetFuncName());
	}
	assert(0 > this->AllocPointDelta);
	for (size_t i = 0; i < this->LocalVarTable.size(); ++i) {
		assert(this->LocalVarTable.at(i).offset >= 0);
		// Picture that AllocPointDelta is -200, MinStackDelta is -210, and
		//  the LocalVarTable[i].offset is +8 (i.e. 8 bytes above alloc point).
		//  Then base = 8 + (-200 - -210) = 8 + 10 = 18, the proper offset into
		//  the StackFrameMap.
		size_t base = (size_t) (this->LocalVarTable.at(i).offset
			+ (this->AllocPointDelta - this->MinStackDelta));
		size_t limit = base + this->LocalVarTable.at(i).size;
		if (limit > this->StackFrameMap.size()) {
			msg("ERROR: base = %d limit = %d StackFrameMap size = %d\n", base, limit,
				this->StackFrameMap.size());
		}
		assert(limit <= this->StackFrameMap.size());
		for (size_t MapIndex = base; MapIndex < limit; ++MapIndex) {
			this->StackFrameMap[MapIndex].VarPtr = &(this->LocalVarTable.at(i));
		}
	}

	// Iterate through all instructions and record stack frame accesses in the StackFrameMap.
	for (CurrInst = this->Instrs.begin(); CurrInst != this->Instrs.end(); ++CurrInst) {
#if SMP_USE_SSA_FNOP_MARKER
		if (this->Instrs.begin() == CurrInst)
			continue;  // skip marker instruction
#endif

		sval_t sp_delta = get_spd(&(this->FuncInfo), CurrInst->GetAddr());
		if (0 < sp_delta) {
			// Stack underflow; about to assert
			msg("Stack underflow at %x %s sp_delta: %d\n", CurrInst->GetAddr(),
				CurrInst->GetDisasm(), sp_delta);
		}
		assert(0 >= sp_delta);
		ea_t offset;
		size_t DataSize;
		bool UsedFramePointer;
		if (CurrInst->HasDestMemoryOperand()) {
			set<DefOrUse, LessDefUse>::iterator CurrDef;
			for (CurrDef = CurrInst->GetFirstDef(); CurrDef != CurrInst->GetLastDef(); ++CurrDef) {
				op_t TempOp = CurrDef->GetOp();
				if (TempOp.type != o_phrase && TempOp.type != o_displ)
					continue;
				if (this->MDGetStackOffsetAndSize(TempOp, sp_delta, offset, DataSize, UsedFramePointer)) {
					assert(0 <= offset);
					if (offset >= this->FuncInfo.frsize)
						continue;  // limit processing to outgoing args and locals
					if ((offset + DataSize) > this->StackFrameMap.size()) {
						msg("ERROR: offset = %d DataSize = %d FrameMapSize = %d\n",
							offset, DataSize, this->StackFrameMap.size());
					}
					assert((offset + DataSize) <= this->StackFrameMap.size());
					for (int j = 0; j < (int) DataSize; ++j) {
						this->StackFrameMap[offset + j].Written = true;
						if (!UsedFramePointer)
							this->StackFrameMap[offset + j].ESPRelativeAccess = true;
						else
							this->StackFrameMap[offset + j].EBPRelativeAccess = true;
					}
				}
			} // end for all DEFs
		} // end if DestMemoryOperand

		if (CurrInst->HasSourceMemoryOperand()) {
			set<DefOrUse, LessDefUse>::iterator CurrUse;
			for (CurrUse = CurrInst->GetFirstUse(); CurrUse != CurrInst->GetLastUse(); ++CurrUse) {
				op_t TempOp = CurrUse->GetOp();
				if (TempOp.type != o_phrase && TempOp.type != o_displ)
					continue;
				if (this->MDGetStackOffsetAndSize(TempOp, sp_delta, offset, DataSize, UsedFramePointer)) {
					assert(0 <= offset);
					if (offset >= this->FuncInfo.frsize)
						continue;  // limit processing to outgoing args and locals
					if ((offset + DataSize) > this->StackFrameMap.size()) {
						msg("ERROR: offset = %d DataSize = %d FrameMapSize = %d\n",
							offset, DataSize, this->StackFrameMap.size());
					}
					assert((offset + DataSize) <= this->StackFrameMap.size());
					for (int j = 0; j < (int) DataSize; ++j) {
						this->StackFrameMap[offset + j].Read = true;
						if (!UsedFramePointer)
							this->StackFrameMap[offset + j].ESPRelativeAccess = true;
						else
							this->StackFrameMap[offset + j].EBPRelativeAccess = true;
					}
				}
			} // end for all USEs
		} // end if SourceMemoryOperand
		// NOTE: Detect taking the address of stack locations. **!!**
	} // end for all instructions

	// If function is a leaf function, set OutgoingArgsSize to zero and return.
	if (this->IsLeaf()) {
		this->OutgoingArgsSize = 0;
		return;
	}

	// For non-leaf functions, set the OutgoingArgsSize to the write-only, ESP-relative
	//  region of the bottom of the StackFrameMap.
	for (size_t MapIndex = 0; MapIndex < this->StackFrameMap.size(); ++MapIndex) {
		// Some of the bottom of the stack frame might be below the local frame allocation.
		//  These are pushes that happened after allocation, etc. We skip over these
		//  locations and define the outgoing args region to start strictly at the bottom
		//  of the local frame allocation.
		struct StackFrameEntry TempEntry = this->StackFrameMap.at(MapIndex);
		if (DebugFlag) {
			msg("StackFrameMap entry %d: offset: %d Read: %d Written: %d ESP: %d EBP: %d\n",
				MapIndex, TempEntry.offset, TempEntry.Read, TempEntry.Written,
				TempEntry.ESPRelativeAccess, TempEntry.EBPRelativeAccess);
		}
		if (TempEntry.offset < this->AllocPointDelta)
			continue;
		if (TempEntry.Read || TempEntry.EBPRelativeAccess || !TempEntry.Written
			|| !TempEntry.ESPRelativeAccess)
			break;
		this->OutgoingArgsSize++;
	}
	// Sometimes we encounter unused stack space above the outgoing args. Lump this space
	//  in with the outgoing args. We detect this by noting when the outgoing args space
	//  has only partially used the space assigned to a local var.
	if ((0 < this->OutgoingArgsSize) && (this->OutgoingArgsSize < this->FuncInfo.frsize)) {
		long MapIndex = (this->AllocPointDelta - this->MinStackDelta);
		assert(0 <= MapIndex);
		MapIndex += (((long) this->OutgoingArgsSize) - 1);
		struct StackFrameEntry TempEntry = this->StackFrameMap.at((size_t) MapIndex);
		if (this->OutgoingArgsSize < (TempEntry.VarPtr->offset + TempEntry.VarPtr->size)) {