Package ghidra.pcode.emu.jit.analysis

Class JitDataFlowState

java.lang.Object

ghidra.pcode.emu.jit.analysis.JitDataFlowState

All Implemented Interfaces:

PcodeExecutorState<JitVal>, PcodeExecutorStatePiece<JitVal,JitVal>

public class JitDataFlowState
extends Object
implements PcodeExecutorState<JitVal>

An implementation of PcodeExecutorState for per-block data flow interpretation

In p-code interpretation, this interface's purpose is to store the current value of varnodes in the emulation/interpretation state. Here we implement it using T:=JitVal, and track the latest variable definition of vanodes in the data flow interpretation. The adaptation is fairly straightforward, except when varnode accesses do not match their latest definitions exactly, e.g., an access of EAX when the latest definition is for RAX. Thus, this state object may synthesize subpiece and catenate ops to model the "off-cut" use of one or more such definitions. Additionally, in preparation for inter-block data flow analysis, when no definition is present for a varnode (or part of a varnode) access, this state will synthesize phi ops. See setVar and getVar for details.

This state only serves to analyze data flow through register and unique variables. Because we know these are only accessible to the thread, we stand to save much execution time by bypassing the JitBytesPcodeExecutorState at run time. We can accomplish this by mapping these variables to suitable JVM local variables. Thus, we have one map of entries for register space and another for unique space. Accesses to other spaces do not mutate or read from either of those maps, but this class may generate a suitable JitVal for the use-def graph.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	JitDataFlowState.MiniDFState	A minimal data flow machine state that can be captured by a JitCallOtherOpIf.

Nested classes/interfaces inherited from interface ghidra.pcode.exec.PcodeExecutorStatePiece

PcodeExecutorStatePiece.Reason

Method Summary

Modifier and Type	Method	Description
JitDataFlowState.MiniDFState	captureState()	Capture the current state of intra-block analysis.
void	clear()	Erase the entire state or piece
PcodeExecutorState<JitVal>	fork()	Create a deep copy of this state
JitDataFlowArithmetic	getArithmetic()	Get the arithmetic used to manipulate values of the type stored by this state
MemBuffer	getConcreteBuffer(Address address, PcodeArithmetic.Purpose purpose)	Bind a buffer of concrete bytes at the given start address
List<JitVal>	getDefinitions(Register register)	Get an ordered list of all values involved in the latest definition of the given varnode.
List<JitVal>	getDefinitions(Varnode varnode)	Get an ordered list of all values involved in the latest definition of the given varnode.
Language	getLanguage()	Get the language defining the address spaces of this state piece
Map<Register,JitVal>	getRegisterValues()	Get all register values known to this state
JitVal	getVar(AddressSpace space, JitVal offset, int size, boolean quantize, PcodeExecutorStatePiece.Reason reason)	Get the value of a variable
Set<Varnode>	getVarnodesRead()	Get a complete catalog of all varnodes read, including overlapping, subregs, etc.
Set<Varnode>	getVarnodesWritten()	Get a complete catalog of all varnodes written, including overlapping, subregs, etc.
void	setVar(AddressSpace space, JitVal offset, int size, boolean quantize, JitVal val)	Set the value of a variable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ghidra.pcode.exec.PcodeExecutorState

getAddressArithmetic, paired

Methods inherited from interface ghidra.pcode.exec.PcodeExecutorStatePiece

checkRange, getVar, getVar, getVar, getVar, quantizeOffset, setVar, setVar, setVar, setVar

Method Details

getLanguage

public Language getLanguage()

Description copied from interface: PcodeExecutorStatePiece

Get the language defining the address spaces of this state piece

Specified by:

getLanguage in interface PcodeExecutorStatePiece<JitVal,JitVal>

Returns:

the language

getArithmetic

public JitDataFlowArithmetic getArithmetic()

Description copied from interface: PcodeExecutorStatePiece

Get the arithmetic used to manipulate values of the type stored by this state

Specified by:

getArithmetic in interface PcodeExecutorStatePiece<JitVal,JitVal>

Returns:

the arithmetic

setVar

public void setVar(AddressSpace space,
 JitVal offset,
 int size,
 boolean quantize,
 JitVal val)

Set the value of a variable

This and getVar(AddressSpace, JitVal, int, boolean, Reason) are where we connect the interpretation to the maps of definitions we keep in this state. We examine the varnode's type first. We can't write to a constant, and that shouldn't be allowed anyway, so we warn if we observe that. We'll ignore any indirect writes, because those are denoted by store ops. We also don't do much here with direct writes. The writes to such variables are handled by JitMemoryOutVar. Such output variables are actually passed in as val here, but need only be stored in a map if they are register or unique variables.

Specified by:

setVar in interface PcodeExecutorStatePiece<JitVal,JitVal>

Parameters:

space - the address space

offset - the offset within the space

size - the size of the variable

quantize - true to quantize to the language's "addressable unit"

val - the value

getDefinitions

public List<JitVal> getDefinitions(Varnode varnode)

Get an ordered list of all values involved in the latest definition of the given varnode.

Parameters:

varnode - the varnode whose definitions to retrieve

Returns:

the list of values

See Also:

• JitDataFlowState.MiniDFState.getDefinitions(AddressSpace, long, int)

getDefinitions

public List<JitVal> getDefinitions(Register register)

Get an ordered list of all values involved in the latest definition of the given varnode.

Parameters:

register - the register whose definitions to retrieve

Returns:

the list of values

See Also:

• JitDataFlowState.MiniDFState.getDefinitions(AddressSpace, long, int)

getVar

public JitVal getVar(AddressSpace space,
 JitVal offset,
 int size,
 boolean quantize,
 PcodeExecutorStatePiece.Reason reason)

Get the value of a variable

This and setVar(AddressSpace, JitVal, int, boolean, JitVal) are where we connect the interpretation to the maps of definitions we keep in this state. We examine the varnode's type first. If it's a constant or memory variable, it just returns the appropriate JitConstVal, JitDirectMemoryVar, or JitIndirectMemoryVar. If it's a register or unique, then we retrieve the latest definition(s) as in JitDataFlowState.MiniDFState.getDefinitions(AddressSpace, long, int). In the simple case of an exact definition, we return it. Otherwise, this synthesizes the appropriate op(s), enters them into the use-def graph, and returns the final output.

Specified by:

getVar in interface PcodeExecutorStatePiece<JitVal,JitVal>

Parameters:

space - the address space

offset - the offset within the space

size - the size of the variable

quantize - true to quantize to the language's "addressable unit"

reason - the reason for reading the variable

Returns:

the value

getRegisterValues

public Map<Register,JitVal> getRegisterValues()

Description copied from interface: PcodeExecutorStatePiece

Get all register values known to this state

When the state acts as a cache, it should only return those cached.

Specified by:

getRegisterValues in interface PcodeExecutorStatePiece<JitVal,JitVal>

Returns:

a map of registers and their values

getConcreteBuffer

public MemBuffer getConcreteBuffer(Address address,
 PcodeArithmetic.Purpose purpose)

Description copied from interface: PcodeExecutorStatePiece

Bind a buffer of concrete bytes at the given start address

Specified by:

getConcreteBuffer in interface PcodeExecutorStatePiece<JitVal,JitVal>

Parameters:

address - the start address

purpose - the reason why the emulator needs a concrete value

Returns:

a buffer

clear

public void clear()

Description copied from interface: PcodeExecutorStatePiece

Erase the entire state or piece

This is generally only useful when the state is itself a cache to another object. This will ensure the state is reading from that object rather than a stale cache. If this is not a cache, this could in fact clear the whole state, and the machine using it will be left in the dark.

Specified by:

clear in interface PcodeExecutorStatePiece<JitVal,JitVal>

fork

public PcodeExecutorState<JitVal> fork()

Description copied from interface: PcodeExecutorStatePiece

Create a deep copy of this state

Specified by:

fork in interface PcodeExecutorState<JitVal>

Specified by:

fork in interface PcodeExecutorStatePiece<JitVal,JitVal>

Returns:

the copy

getVarnodesRead

public Set<Varnode> getVarnodesRead()

Get a complete catalog of all varnodes read, including overlapping, subregs, etc.

Returns:

the set of varnodes

getVarnodesWritten

public Set<Varnode> getVarnodesWritten()

Get a complete catalog of all varnodes written, including overlapping, subregs, etc.

Returns:

the set of varnodes

captureState

public JitDataFlowState.MiniDFState captureState()

Capture the current state of intra-block analysis.

This may be required for follow-up op-use analysis by a JitCallOtherOpIf invoked using the standard strategy. All live varnodes at the time of the call must be considered used.

Returns:

the captured state