StackSolver Class Reference

A class that solves for stack-pointer changes across unknown sub-functions. More...

Public Member Functions
void	solve (void)
	Solve the system of equations.
void	build (const Funcdata &data, AddrSpace *id, int4 spcbase)
	Build the system of equations. More...
int4	getNumVariables (void) const
	Get the number of variables in the system.
Varnode *	getVariable (int4 i) const
	Get the i-th Varnode variable.
int4	getCompanion (int4 i) const
	Get the i-th variable's companion index.
int4	getSolution (int4 i) const
	Get the i-th variable's solution.

Private Member Functions
void	duplicate (void)
	Duplicate each equation, multiplying by -1.
void	propagate (int4 varnum, int4 val)
	Propagate solution for one variable to other variables. More...

Private Attributes
vector< StackEqn >	eqs
	Known equations based on operations that explicitly change the stack-pointer.
vector< StackEqn >	guess
	Guessed equations for underdetermined systems.
vector< Varnode * >	vnlist
	The indexed set of variables, one for each reference to the stack-pointer.
vector< int4 >	companion
	Index of companion input for variable produced by CPUI_INDIRECT.
Address	spacebase
	Starting address of the stack-pointer.
vector< int4 >	soln
	Collected solutions (corresponding to array of variables)
int4	missedvariables
	Number of variables for which we are missing an equation.

Detailed Description

A class that solves for stack-pointer changes across unknown sub-functions.

Member Function Documentation

build()

void StackSolver::build	(	const Funcdata &	data,
		AddrSpace *	id,
		int4	spcbase
	)

Build the system of equations.

Collect references to the stack-pointer as variables, and examine their defining PcodeOps to determine equations and coefficient.

Parameters

data	is the function being analyzed
id	is the stack address space
spcbase	is the index, relative to the stack space, of the stack pointer

References Funcdata::beginLoc(), PcodeOp::code(), companion, Varnode::comparePointers(), CPUI_COPY, CPUI_INDIRECT, CPUI_INT_ADD, CPUI_INT_AND, CPUI_MULTIEQUAL, Funcdata::endLoc(), eqs, ProtoModel::extrapop_unknown, Varnode::getAddr(), Funcdata::getCallSpecs(), Varnode::getDef(), PcodeOp::getIn(), Varnode::getOffset(), PcodeOp::getOpFromConst(), Varnode::getSpace(), AddrSpace::getSpacebase(), AddrSpace::getType(), guess, IPTR_IOP, Varnode::isConstant(), missedvariables, PcodeOp::numInput(), StackEqn::rhs, spacebase, StackEqn::var1, StackEqn::var2, and vnlist.

Referenced by ActionStackPtrFlow::analyzeExtraPop().

propagate()

void StackSolver::propagate ( int4  varnum, int4  val  )

private

Propagate solution for one variable to other variables.

Given a solution for one variable, look for equations containing the variable and attempt to solve for the other variable. Continue propagating new solutions to other equations to find even more solutions. Populate the soln array with the solutions.

Parameters

varnum	is the index of the initial variable
val	is the solution for the variable

References StackEqn::compare(), eqs, soln, and StackEqn::var1.

Referenced by solve().

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

• coreaction.cc