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GP-4967: Corrected issues related to emulator cached block instruction

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re-use.
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Dan 2024-09-25 09:57:49 -04:00 committed by ghidra1
parent 025cc9f702
commit e8c28c2a84
2 changed files with 31 additions and 14 deletions
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39
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/emu/SleighInstructionDecoder.java
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@ -15,6 +15,8 @@
*/ */
package ghidra.pcode.emu; package ghidra.pcode.emu;
import java.util.Objects;
import ghidra.app.util.PseudoInstruction; import ghidra.app.util.PseudoInstruction;
import ghidra.pcode.emulate.InstructionDecodeException; import ghidra.pcode.emulate.InstructionDecodeException;
import ghidra.pcode.exec.DecodePcodeExecutionException; import ghidra.pcode.exec.DecodePcodeExecutionException;
@ -73,14 +75,18 @@ public class SleighInstructionDecoder implements InstructionDecoder {
Disassembler.getDisassembler(language, addrFactory, TaskMonitor.DUMMY, listener); Disassembler.getDisassembler(language, addrFactory, TaskMonitor.DUMMY, listener);
} }
@Override protected boolean useCachedInstruction(Address address, RegisterValue context) {
public Instruction decodeInstruction(Address address, RegisterValue context) { if (block == null) {
lastMsg = DEFAULT_ERROR; return false;
if (block != null &&
(instruction = (PseudoInstruction) block.getInstructionAt(address)) != null) {
return instruction;
} }
/* // Always use instruction within last block decoded assuming we flowed from another
// instruction within the same block. The block should be null is starting a new flow.
instruction = (PseudoInstruction) block.getInstructionAt(address);
return instruction != null;
}
protected void parseNewBlock(Address address, RegisterValue context) {
/**
* Parse as few instructions as possible. If more are returned, it's because they form a * Parse as few instructions as possible. If more are returned, it's because they form a
* parallel instruction group. In that case, I should not have to worry self-modifying code * parallel instruction group. In that case, I should not have to worry self-modifying code
* within that group, so no need to re-disassemble after each is executed. * within that group, so no need to re-disassemble after each is executed.
@ -91,17 +97,28 @@ public class SleighInstructionDecoder implements InstructionDecoder {
throw new DecodePcodeExecutionException(lastMsg, address); throw new DecodePcodeExecutionException(lastMsg, address);
} }
instruction = (PseudoInstruction) block.getInstructionAt(address); instruction = (PseudoInstruction) block.getInstructionAt(address);
}
@Override
public Instruction decodeInstruction(Address address, RegisterValue context) {
lastMsg = DEFAULT_ERROR;
if (!useCachedInstruction(address, context)) {
parseNewBlock(address, context);
}
lengthWithDelays = computeLength(); lengthWithDelays = computeLength();
return instruction; return instruction;
} }
@Override @Override
public void branched(Address address) { public void branched(Address address) {
/* /**
* This shouldn't happen in the middle of a parallel instruction group, but in case the * There may be internal branching within a decoded block. Those shouldn't clear the block.
* group modifies itself and jumps back to itself, this will ensure it is re-disassembled. * However, if the cached instruction's context does not match the desired one, assume we're
* starting a new block. That check will have to wait for the decode call, though.
*/ */
block = null; if (block.getInstructionAt(address) == null) {
block = null;
}
} }
/** /**

6
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/AbstractBytesPcodeExecutorStatePiece.java
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@ -4,9 +4,9 @@
* Licensed under the Apache License, Version 2.0 (the "License"); * Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License. * you may not use this file except in compliance with the License.
* You may obtain a copy of the License at * You may obtain a copy of the License at
* *
* http://www.apache.org/licenses/LICENSE-2.0 * http://www.apache.org/licenses/LICENSE-2.0
* *
* Unless required by applicable law or agreed to in writing, software * Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, * distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@ -66,7 +66,7 @@ public abstract class AbstractBytesPcodeExecutorStatePiece<S extends BytesPcodeE
@Override @Override
public Memory getMemory() { public Memory getMemory() {
throw new UnsupportedOperationException(); return null;
} }
@Override @Override