A jump-table execution model. More...

#include <jumptable.hh>

Inheritance diagram for ghidra::JumpModel:

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

virtual	~JumpModel (void)
	Destructor.

virtual bool	isOverride (void) const =0
	Return true if this model was manually overridden.

virtual int4	getTableSize (void) const =0
	Return the number of entries in the address table.

virtual bool	recoverModel (Funcdata fd, PcodeOp indop, uint4 matchsize, uint4 maxtablesize)=0
	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 =0
	Construct the explicit list of target addresses (the Address Table) from this model. More...

virtual void	findUnnormalized (uint4 maxaddsub, uint4 maxleftright, uint4 maxext)=0
	Recover the unnormalized switch variable. More...

virtual void	buildLabels (Funcdata fd, vector< Address > &addresstable, vector< uintb > &label, const JumpModel orig) const =0
	Recover case labels associated with the Address table. More...

virtual Varnode *	foldInNormalization (Funcdata fd, PcodeOp indop)=0
	Do normalization of the given switch specific to this model. More...

virtual bool	foldInGuards (Funcdata fd, JumpTable jump)=0
	Eliminate any guard code involved in computing the switch destination. More...

virtual bool	sanityCheck (Funcdata fd, PcodeOp indop, vector< Address > &addresstable)=0
	Perform a sanity check on recovered addresses. More...

virtual JumpModel *	clone (JumpTable *jt) const =0
	Clone this model.

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

virtual void	encode (Encoder &encoder) const
	Encode this model to a stream.

virtual void	decode (Decoder &decoder)
	Decode this model from a stream.

Protected Attributes
JumpTable *	jumptable
	The jump-table that is building this model.

Detailed Description

A jump-table execution model.

This class holds details of the model and recovers these details in various stages. The model concepts include:

Address Table, the set of destination addresses the jump-table can produce.
Normalized Switch Variable, the Varnode with the most restricted set of values used by the model to produce the destination addresses.
Unnormalized Switch Variable, the Varnode being switched on, as seen in the decompiler output.
Case labels, switch variable values associated with specific destination addresses.
Guards, CBRANCH ops that enforce the normalized switch variable's value range.

Member Function Documentation

◆ buildAddresses()

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

pure 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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasicOverride, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::recoverAddresses(), and ghidra::JumpTable::recoverLabels().

◆ buildLabels()

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

pure 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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasicOverride, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::recoverLabels().

◆ findUnnormalized()

virtual void ghidra::JumpModel::findUnnormalized	(	uint4	maxaddsub,
		uint4	maxleftright,
		uint4	maxext
	)

pure virtual

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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasic2, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::recoverLabels().

◆ foldInGuards()

virtual bool ghidra::JumpModel::foldInGuards	(	Funcdata *	fd,
		JumpTable *	jump
	)

pure 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.

Implemented in ghidra::JumpAssisted, ghidra::JumpBasicOverride, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::foldInGuards().

◆ foldInNormalization()

virtual Varnode* ghidra::JumpModel::foldInNormalization	(	Funcdata *	fd,
		PcodeOp *	indop
	)

pure 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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::foldInNormalization().

◆ recoverModel()

virtual bool ghidra::JumpModel::recoverModel	(	Funcdata *	fd,
		PcodeOp *	indop,
		uint4	matchsize,
		uint4	maxtablesize
	)

pure 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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasicOverride, ghidra::JumpBasic2, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

Referenced by ghidra::JumpTable::recoverLabels().

◆ sanityCheck()

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

pure virtual

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

Implemented in ghidra::JumpAssisted, ghidra::JumpBasicOverride, ghidra::JumpBasic, and ghidra::JumpModelTrivial.

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

jumptable.hh

Public Member Functions

Protected Attributes

Detailed Description

Member Function Documentation

◆ buildAddresses()

◆ buildLabels()

◆ findUnnormalized()

◆ foldInGuards()

◆ foldInNormalization()

◆ recoverModel()

◆ sanityCheck()