A jump-table model assisted by pseudo-op directives in the code. More...

#include <jumptable.hh>

Inheritance diagram for JumpAssisted:

Public Member Functions
	JumpAssisted (JumpTable *jt)
	Constructor.

virtual bool	isOverride (void) const
	Return true if this model was manually overridden.

virtual int4	getTableSize (void) const
	Return the number of entries in the address table.

virtual bool	recoverModel (Funcdata fd, PcodeOp indop, uint4 matchsize, uint4 maxtablesize)
	Attempt to recover details of the model, given a specific BRANCHIND. More...

virtual void	buildAddresses (Funcdata fd, PcodeOp indop, vector< Address > &addresstable, vector< LoadTable > *loadpoints) const
	Construct the explicit list of target addresses (the Address Table) from this model. More...

virtual void	findUnnormalized (uint4 maxaddsub, uint4 maxleftright, uint4 maxext)
	Recover the unnormalized switch variable. More...

virtual void	buildLabels (Funcdata fd, vector< Address > &addresstable, vector< uintb > &label, const JumpModel orig) const
	Recover case labels associated with the Address table. More...

virtual Varnode *	foldInNormalization (Funcdata fd, PcodeOp indop)
	Do normalization of the given switch specific to this model. More...

virtual bool	foldInGuards (Funcdata fd, JumpTable jump)
	Eliminate any guard code involved in computing the switch destination. More...

virtual bool	sanityCheck (Funcdata fd, PcodeOp indop, vector< Address > &addresstable)
	Perform a sanity check on recovered addresses. More...

virtual JumpModel *	clone (JumpTable *jt) const
	Clone this model.

virtual void	clear (void)
	Clear any non-permanent aspects of the model.

Public Member Functions inherited from JumpModel
	JumpModel (JumpTable *jt)
	Construct given a parent jump-table.

virtual	~JumpModel (void)
	Destructor.

virtual void	saveXml (ostream &s) const
	Save this model as an XML tag.

virtual void	restoreXml (const Element el, Architecture glb)
	Restore this model from an XML tag.

Private Attributes
PcodeOp *	assistOp
	The jumpassist PcodeOp.

JumpAssistOp *	userop
	The jumpassist p-code models.

int4	sizeIndices
	Total number of indices in the table (not including the defaultaddress)

Varnode *	switchvn
	The switch variable.

Additional Inherited Members
Protected Attributes inherited from JumpModel
JumpTable *	jumptable
	The jump-table that is building this model.

Detailed Description

A jump-table model assisted by pseudo-op directives in the code.

This model looks for a special jumpassist pseudo-op near the branch site, which contains p-code models describing how to parse a jump-table for case labels and addresses. It views the switch table calculation as a two-stage process:

case2index: convert the switchvar to an index into a table
index2address: convert the index to an address

The pseudo-op holds:

the table address, size (number of indices)
exemplar p-code for inverting the case2index part of the calculation
exemplar p-code for calculating index2address

Member Function Documentation

void JumpAssisted::buildAddresses	(	Funcdata *	fd,
		PcodeOp *	indop,
		vector< Address > &	addresstable,
		vector< LoadTable > *	loadpoints
	)		const

virtual

Construct the explicit list of target addresses (the Address Table) from this model.

The addresses produced all come from the BRANCHIND and may not be deduped. Alternate guard destinations are not yet included.

Parameters

fd	is the function containing the switch
indop	is the root BRANCHIND of the switch
addresstable	will hold the list of Addresses
loadpoints	if non-null will hold LOAD table information used by the model

Implements JumpModel.

References ExecutablePcode::evaluate(), PcodeOp::getAddr(), Funcdata::getArch(), PcodeInjectLibrary::getPayload(), Address::getSpace(), Architecture::pcodeinjectlib, and InjectPayload::sizeInput().

void JumpAssisted::buildLabels	(	Funcdata *	fd,
		vector< Address > &	addresstable,
		vector< uintb > &	label,
		const JumpModel *	orig
	)		const

virtual

Recover case labels associated with the Address table.

The unnormalized switch variable must already be recovered. Values that the normalized switch value can hold or walked back to obtain the value that the unnormalized switch variable would hold. Labels are returned in the order provided by normalized switch variable iterator JumpValues.

Parameters

fd	is the function containing the switch
addresstable	is the address table (used to label code blocks with bad or missing labels)
label	will hold recovered labels in JumpValues order
orig	is the JumpModel to use for the JumpValues iterator

Implements JumpModel.

References ExecutablePcode::evaluate(), Funcdata::getArch(), PcodeInjectLibrary::getPayload(), Architecture::pcodeinjectlib, and InjectPayload::sizeInput().

virtual void JumpAssisted::findUnnormalized	(	uint4	maxaddsub,
		uint4	maxleftright,
		uint4	maxext
	)

inlinevirtual

Recover the unnormalized switch variable.

The normalized switch variable must already be recovered. The amount of normalization between the two switch variables can be restricted.

Parameters

maxaddsub	is a restriction on arithmetic operations
maxleftright	is a restriction on shift operations
maxext	is a restriction on extension operations

Implements JumpModel.

bool JumpAssisted::foldInGuards	(	Funcdata *	fd,
		JumpTable *	jump
	)

virtual

Eliminate any guard code involved in computing the switch destination.

We now think of the BRANCHIND as encompassing any guard function.

Parameters

fd	is the function containing the switch
jump	is the JumpTable owning this model.

Implements JumpModel.

References JumpTable::getDefaultBlock(), and JumpTable::setLastAsMostCommon().

Varnode * JumpAssisted::foldInNormalization	(	Funcdata *	fd,
		PcodeOp *	indop
	)

virtual

Do normalization of the given switch specific to this model.

The PcodeOp machinery is removed so it looks like the CPUI_BRANCHIND simply takes the switch variable as an input Varnode and automatically interprets its values to reach the correct destination.

Parameters

fd	is the function containing the switch
indop	is the given switch as a CPUI_BRANCHIND

Returns: the Varnode holding the final unnormalized switch variable

Implements JumpModel.

References Varnode::beginDescend(), Varnode::endDescend(), Funcdata::opDestroy(), Funcdata::opSetInput(), and JumpBasic::switchvn.

bool JumpAssisted::recoverModel	(	Funcdata *	fd,
		PcodeOp *	indop,
		uint4	matchsize,
		uint4	maxtablesize
	)

virtual

Attempt to recover details of the model, given a specific BRANCHIND.

This generally recovers the normalized switch variable and any guards.

Parameters

fd	is the function containing the switch
indop	is the given BRANCHIND
matchsize	is the expected number of address table entries to recover, or 0 for no expectation
maxtablesize	is maximum number of address table entries to allow in the model

Returns: true if details of the model were successfully recovered

Implements JumpModel.

References CPUI_CALLOTHER, ExecutablePcode::evaluate(), Funcdata::getArch(), Varnode::getDef(), PcodeOp::getIn(), Varnode::getOffset(), UserOpManage::getOp(), PcodeInjectLibrary::getPayload(), Varnode::isWritten(), Architecture::pcodeinjectlib, InjectPayload::sizeInput(), JumpBasic::switchvn, and Architecture::userops.

virtual bool JumpAssisted::sanityCheck	(	Funcdata *	fd,
		PcodeOp *	indop,
		vector< Address > &	addresstable
	)

inlinevirtual

Perform a sanity check on recovered addresses.

Individual addresses are checked against the function or its program to determine if they are reasonable. This method can optionally remove addresses from the table. If it does so, the underlying model is changed to reflect the removal.

Parameters

fd	is the function containing the switch
indop	is the root BRANCHIND of the switch
addresstable	is the list of recovered Addresses, which may be modified

Returns: true if there are (at least some) reasonable addresses in the table

Implements JumpModel.

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

jumptable.hh
jumptable.cc

Public Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation