ghidra::EmulateFunction Class Reference

A light-weight emulator to calculate switch targets from switch variables. More...

#include <jumptable.hh>

Inheritance diagram for ghidra::EmulateFunction:

Public Member Functions
	EmulateFunction (Funcdata *f)
	Constructor. More...
void	setLoadCollect (bool val)
	Set whether we collect LOAD information.
virtual void	setExecuteAddress (const Address &addr)
	Set the address of the next instruction to emulate.
virtual uintb	getVarnodeValue (Varnode *vn) const
	Given a specific Varnode, retrieve the current value for it from the machine state. More...
virtual void	setVarnodeValue (Varnode *vn, uintb val)
	Given a specific Varnode, set the given value for it in the current machine state. More...
uintb	emulatePath (uintb val, const PathMeld &pathMeld, PcodeOp *startop, Varnode *startvn)
	Execute from a given starting point and value to the common end-point of the path set. More...
void	collectLoadPoints (vector< LoadTable > &res) const
	Recover any LOAD table descriptions. More...
Public Member Functions inherited from ghidra::EmulatePcodeOp
	EmulatePcodeOp (Architecture *g)
	Constructor. More...
void	setCurrentOp (PcodeOp *op)
	Establish the current PcodeOp being emulated. More...
virtual Address	getExecuteAddress (void) const
	Get the address of the current instruction being executed.
Public Member Functions inherited from ghidra::Emulate
	Emulate (void)
	generic emulator constructor
void	setHalt (bool val)
	Set the halt state of the emulator. More...
bool	getHalt (void) const
	Get the halt state of the emulator. More...
void	executeCurrentOp (void)
	Do a single pcode op step. More...

Private Member Functions
virtual void	executeLoad (void)
	Standard behavior for a p-code LOAD.
virtual void	executeBranch (void)
	Standard behavior for a BRANCH. More...
virtual void	executeBranchind (void)
	Standard behavior for a BRANCHIND.
virtual void	executeCall (void)
	Standard behavior for a p-code CALL.
virtual void	executeCallind (void)
	Standard behavior for a CALLIND.
virtual void	executeCallother (void)
	Standard behavior for a user-defined p-code op.
virtual void	fallthruOp (void)
	Standard p-code fall-thru semantics.

Private Attributes
Funcdata *	fd
	The function being emulated.
map< Varnode *, uintb >	varnodeMap
	Light-weight memory state based on Varnodes.
bool	collectloads
	Set to true if the emulator collects individual LOAD addresses.
vector< LoadTable >	loadpoints
	The set of collected LOAD records.

Additional Inherited Members
Protected Member Functions inherited from ghidra::EmulatePcodeOp
virtual uintb	getLoadImageValue (AddrSpace *spc, uintb offset, int4 sz) const
	Pull a value from the load-image given a specific address. More...
virtual void	executeUnary (void)
	Execute a unary arithmetic/logical operation.
virtual void	executeBinary (void)
	Execute a binary arithmetic/logical operation.
virtual void	executeStore (void)
	Standard behavior for a p-code STORE.
virtual bool	executeCbranch (void)
	Check if the conditional of a CBRANCH is true. More...
virtual void	executeMultiequal (void)
	Standard behavior for a MULTIEQUAL (phi-node)
virtual void	executeIndirect (void)
	Standard behavior for an INDIRECT op.
virtual void	executeSegmentOp (void)
	Behavior for a SEGMENTOP.
virtual void	executeCpoolRef (void)
	Standard behavior for a CPOOLREF (constant pool reference) op.
virtual void	executeNew (void)
	Standard behavior for (low-level) NEW op.
Protected Attributes inherited from ghidra::EmulatePcodeOp
Architecture *	glb
	The underlying Architecture for the program being emulated.
PcodeOp *	currentOp
	Current PcodeOp being executed.
PcodeOp *	lastOp
	Last PcodeOp that was executed.
Protected Attributes inherited from ghidra::Emulate
bool	emu_halted
	Set to true if the emulator is halted.
OpBehavior *	currentBehave
	Behavior of the next op to execute.

Detailed Description

A light-weight emulator to calculate switch targets from switch variables.

We assume we only have to store memory state for individual Varnodes and that dynamic LOADs are resolved from the LoadImage. BRANCH and CBRANCH emulation will fail, there can only be one execution path, although there can be multiple data-flow paths.

Constructor & Destructor Documentation

EmulateFunction()

ghidra::EmulateFunction::EmulateFunction

(

Funcdata *

f

)

Constructor.

Parameters

f	is the function to emulate within

References collectloads, and fd.

Member Function Documentation

collectLoadPoints()

void ghidra::EmulateFunction::collectLoadPoints

(

vector< LoadTable > &

res

)

const

Recover any LOAD table descriptions.

Pass back any LOAD records collected during emulation. The individual records are sorted and collapsed into concise table descriptions.

Parameters

res	will hold any resulting table descriptions

References ghidra::LoadTable::collapseTable(), and loadpoints.

Referenced by ghidra::JumpBasic::buildAddresses().

emulatePath()

uintb ghidra::EmulateFunction::emulatePath	(	uintb	val,
		const PathMeld &	pathMeld,
		PcodeOp *	startop,
		Varnode *	startvn
	)

Execute from a given starting point and value to the common end-point of the path set.

Flow the given value through all paths in the path container to produce the single output value.

Parameters

val	is the starting value
pathMeld	is the set of paths to execute
startop	is the starting PcodeOp within the path set
startvn	is the Varnode holding the starting value

Returns

the calculated value at the common end-point

References ghidra::PcodeOp::code(), ghidra::CPUI_MULTIEQUAL, ghidra::Emulate::executeCurrentOp(), ghidra::PcodeOp::getAddr(), ghidra::PcodeOp::getIn(), ghidra::PathMeld::getOp(), ghidra::PcodeOp::getOut(), getVarnodeValue(), ghidra::Varnode::isConstant(), ghidra::PcodeOp::numInput(), ghidra::PathMeld::numOps(), ghidra::EmulatePcodeOp::setCurrentOp(), and setVarnodeValue().

Referenced by ghidra::JumpBasic::buildAddresses(), and ghidra::JumpBasicOverride::trialNorm().

executeBranch()

void ghidra::EmulateFunction::executeBranch ( void  )

privatevirtual

Standard behavior for a BRANCH.

This routine performs a standard p-code BRANCH operation on the memory state. This same routine is used for CBRANCH operations if the condition has evaluated to true.

Implements ghidra::Emulate.

getVarnodeValue()

uintb ghidra::EmulateFunction::getVarnodeValue ( Varnode *  vn ) const

virtual

Given a specific Varnode, retrieve the current value for it from the machine state.

This is the placeholder internal operation for obtaining a Varnode value during emulation. The value is loaded using the Varnode as the address and storage size.

Parameters

vn	is the specific Varnode

Returns

the corresponding value from the machine state

Implements ghidra::EmulatePcodeOp.

References ghidra::EmulatePcodeOp::getLoadImageValue(), ghidra::Varnode::getOffset(), ghidra::Varnode::getSize(), ghidra::Varnode::getSpace(), ghidra::Varnode::isConstant(), and varnodeMap.

Referenced by emulatePath().

setVarnodeValue()

void ghidra::EmulateFunction::setVarnodeValue ( Varnode *  vn, uintb  val  )

virtual

Given a specific Varnode, set the given value for it in the current machine state.

This is the placeholder internal operation for setting a Varnode value during emulation. The value is stored using the Varnode as the address and storage size.

Parameters

vn	is the specific Varnode
val	is the constant value to store

Implements ghidra::EmulatePcodeOp.

References varnodeMap.

Referenced by emulatePath().

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The documentation for this class was generated from the following files:

• jumptable.hh
• jumptable.cc