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https://github.com/NationalSecurityAgency/ghidra.git
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GP-4782 Refactor RulePtrsubUndo
This commit is contained in:
caheckman
parent
be305db930
commit
34adcff830
7 changed files with 355 additions and 80 deletions
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@ -4,9 +4,9 @@
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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@ -5920,30 +5920,30 @@ bool AddTreeState::spanAddTree(PcodeOp *op,uint8 treeCoeff)
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void AddTreeState::calcSubtype(void)
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{
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if (size == 0 || nonmultsum < size)
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offset = nonmultsum;
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uint8 tmpoff = (multsum + nonmultsum) & ptrmask;
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if (size == 0 || tmpoff < size)
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offset = tmpoff;
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else {
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// For a sum that falls completely outside the data-type, there is presumably some
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// type of constant term added to an array index either at the current level or lower.
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// If we knew here whether an array of the baseType was possible we could make a slightly
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// better decision.
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intb snonmult = sign_extend(nonmultsum,ptrsize*8-1);
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snonmult = snonmult % size;
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if (snonmult >= 0)
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intb stmpoff = sign_extend(tmpoff,ptrsize*8-1);
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stmpoff = stmpoff % size;
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if (stmpoff >= 0)
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// We assume the sum is big enough it represents an array index at this level
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offset = (uint8)snonmult;
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offset = (uint8)stmpoff;
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else {
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// For a negative sum, if the baseType is a structure and there is array hints,
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// we assume the sum is an array index at a lower level
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if (baseType->getMetatype() == TYPE_STRUCT && biggestNonMultCoeff != 0)
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offset = nonmultsum;
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if (baseType->getMetatype() == TYPE_STRUCT && biggestNonMultCoeff != 0 && multsum == 0)
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offset = tmpoff;
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else
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offset = (uint8)(snonmult + size);
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offset = (uint8)(stmpoff + size);
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}
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}
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correct = nonmultsum - offset;
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nonmultsum = offset;
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multsum = (multsum + correct) & ptrmask; // Some extra multiples of size
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correct = nonmultsum; // Non-multiple constants are double counted, correct in final sum
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multsum = (tmpoff - offset) & ptrmask; // Some extra multiples of size
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if (nonmult.empty()) {
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if ((multsum == 0) && multiple.empty()) { // Is there anything at all
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valid = false;
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@ -5952,31 +5952,33 @@ void AddTreeState::calcSubtype(void)
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isSubtype = false; // There are no offsets INTO the pointer
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}
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else if (baseType->getMetatype() == TYPE_SPACEBASE) {
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int8 nonmultbytes = AddrSpace::addressToByteInt(nonmultsum,ct->getWordSize()); // Convert to bytes
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int8 offsetbytes = AddrSpace::addressToByteInt(offset,ct->getWordSize()); // Convert to bytes
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int8 extra;
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// Get offset into mapped variable
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if (!hasMatchingSubType(nonmultbytes, biggestNonMultCoeff, &extra)) {
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if (!hasMatchingSubType(offsetbytes, biggestNonMultCoeff, &extra)) {
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valid = false; // Cannot find mapped variable but nonmult is non-empty
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return;
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}
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extra = AddrSpace::byteToAddress(extra, ct->getWordSize()); // Convert back to address units
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offset = (nonmultsum - extra) & ptrmask;
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offset = (offset - extra) & ptrmask;
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correct = (correct - extra) & ptrmask;
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isSubtype = true;
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}
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else if (baseType->getMetatype() == TYPE_STRUCT) {
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intb snonmult = sign_extend(nonmultsum,ptrsize*8-1);
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int8 nonmultbytes = AddrSpace::addressToByteInt(snonmult,ct->getWordSize()); // Convert to bytes
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intb soffset = sign_extend(offset,ptrsize*8-1);
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int8 offsetbytes = AddrSpace::addressToByteInt(soffset,ct->getWordSize()); // Convert to bytes
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int8 extra;
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// Get offset into field in structure
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if (!hasMatchingSubType(nonmultbytes, biggestNonMultCoeff, &extra)) {
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if (nonmultbytes < 0 || nonmultbytes >= baseType->getSize()) { // Compare as bytes! not address units
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if (!hasMatchingSubType(offsetbytes, biggestNonMultCoeff, &extra)) {
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if (offsetbytes < 0 || offsetbytes >= baseType->getSize()) { // Compare as bytes! not address units
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valid = false; // Out of structure's bounds
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return;
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}
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extra = 0; // No field, but pretend there is something there
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}
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extra = AddrSpace::byteToAddressInt(extra, ct->getWordSize()); // Convert back to address units
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offset = (nonmultsum - extra) & ptrmask;
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offset = (offset - extra) & ptrmask;
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correct = (correct - extra) & ptrmask;
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if (pRelType != (TypePointerRel *)0 && offset == pRelType->getPointerOffset()) {
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// offset falls within basic ptrto
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if (!pRelType->evaluateThruParent(0)) { // If we are not representing offset 0 through parent
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@ -5988,12 +5990,31 @@ void AddTreeState::calcSubtype(void)
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}
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else if (baseType->getMetatype() == TYPE_ARRAY) {
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isSubtype = true;
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correct = (correct - offset) & ptrmask;
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offset = 0;
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}
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else {
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// No struct or array, but nonmult is non-empty
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valid = false; // There is substructure we don't know about
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}
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if (pRelType != (const TypePointerRel *)0) {
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int4 ptrOff = ((TypePointerRel *)ct)->getPointerOffset();
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offset = (offset - ptrOff) & ptrmask;
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correct = (correct - ptrOff) & ptrmask;
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}
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}
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/// The data-type from the pointer input (of either a PTRSUB or PTRADD) is propagated to the
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/// output of the PcodeOp.
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/// \param op is the given PcodeOp
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void AddTreeState::assignPropagatedType(PcodeOp *op)
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{
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Varnode *vn = op->getIn(0);
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Datatype *inType = vn->getTypeReadFacing(op);
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Datatype *newType = op->getOpcode()->propagateType(inType, op, vn, op->getOut(), 0, -1);
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if (newType != (Datatype *)0)
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op->getOut()->updateType(newType, false, false);
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}
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/// Construct part of the tree that sums to a multiple of the base data-type size.
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@ -6037,7 +6058,6 @@ Varnode *AddTreeState::buildMultiples(void)
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Varnode *AddTreeState::buildExtra(void)
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{
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correct = correct+offset; // Total correction that needs to be made
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Varnode *resNode = (Varnode *)0;
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for(int4 i=0;i<nonmult.size();++i) {
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Varnode *vn = nonmult[i];
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@ -6138,11 +6158,6 @@ bool AddTreeState::apply(void)
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void AddTreeState::buildTree(void)
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{
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if (pRelType != (const TypePointerRel *)0) {
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int4 ptrOff = ((TypePointerRel *)ct)->getPointerOffset();
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offset -= ptrOff;
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offset &= ptrmask;
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}
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Varnode *multNode = buildMultiples();
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Varnode *extraNode = buildExtra();
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PcodeOp *newop = (PcodeOp *)0;
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@ -6152,6 +6167,8 @@ void AddTreeState::buildTree(void)
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newop = data.newOpBefore(baseOp,CPUI_PTRADD,ptr,multNode,data.newConstant(ptrsize,size));
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if (ptr->getType()->needsResolution())
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data.inheritResolution(ptr->getType(),newop, 0, baseOp, baseSlot);
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if (data.isTypeRecoveryExceeded())
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assignPropagatedType(newop);
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multNode = newop->getOut();
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}
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else
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@ -6162,6 +6179,8 @@ void AddTreeState::buildTree(void)
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newop = data.newOpBefore(baseOp,CPUI_PTRSUB,multNode,data.newConstant(ptrsize,offset));
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if (multNode->getType()->needsResolution())
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data.inheritResolution(multNode->getType(),newop, 0, baseOp, baseSlot);
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if (data.isTypeRecoveryExceeded())
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assignPropagatedType(newop);
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if (size != 0)
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newop->setStopTypePropagation();
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multNode = newop->getOut();
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@ -6555,6 +6574,8 @@ int4 RulePtraddUndo::applyOp(PcodeOp *op,Funcdata &data)
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return 1;
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}
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const int4 RulePtrsubUndo::DEPTH_LIMIT = 8;
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/// \class RulePtrsubUndo
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/// \brief Remove PTRSUB operations with mismatched data-type information
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///
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@ -6567,17 +6588,204 @@ void RulePtrsubUndo::getOpList(vector<uint4> &oplist) const
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oplist.push_back(CPUI_PTRSUB);
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}
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/// \brief Recursively search for additive constants and multiplicative constants
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///
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/// Walking backward from the given Varnode, search for constants being added in and return
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/// the sum of all the constants. Additionally pass back the biggest constant coefficient, for any term
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/// formed with INT_MULT.
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/// \param vn is the given root Varnode of the additive tree
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/// \param multiplier will hold the biggest constant coefficient
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/// \param maxLevel is the maximum depth to search in the tree
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/// \return the sum of all constants in the additive expression
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int8 RulePtrsubUndo::getConstOffsetBack(Varnode *vn,int8 &multiplier,int4 maxLevel)
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{
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multiplier = 1;
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int8 submultiplier;
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if (vn->isConstant())
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return vn->getOffset();
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if (!vn->isWritten())
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return 0;
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maxLevel -= 1;
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if (maxLevel < 0)
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return 0;
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PcodeOp *op = vn->getDef();
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OpCode opc = op->code();
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int8 retval = 0;
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if (opc == CPUI_INT_ADD) {
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retval += getConstOffsetBack(op->getIn(0),submultiplier,maxLevel);
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if (submultiplier > multiplier)
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multiplier = submultiplier;
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retval += getConstOffsetBack(op->getIn(1), submultiplier, maxLevel);
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if (submultiplier > multiplier)
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multiplier = submultiplier;
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}
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else if (opc == CPUI_INT_MULT) {
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Varnode *cvn = op->getIn(1);
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if (!cvn->isConstant()) return 0;
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multiplier = cvn->getOffset();
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getConstOffsetBack(op->getIn(0), submultiplier, maxLevel);
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multiplier *= submultiplier; // Only contribute to the multiplier
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}
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return retval;
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}
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/// \brief Collect constants and the biggest multiplier in the given PTRSUB expression.
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///
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/// Walking the additive expression (INT_ADD, PTRADD, and other PTRSUBs) and calculate any additional
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/// constant value being added to the PTRSUB. Additionally pass back the biggest constant coefficient of any
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/// multiplicative term in the expression.
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/// \param op is the given PTRSUB
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/// \param multiplier will hold the biggest multiplicative coefficient
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int8 RulePtrsubUndo::getExtraOffset(PcodeOp *op,int8 &multiplier)
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{
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int8 extra = 0;
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multiplier = 1;
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int8 submultiplier;
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Varnode *outvn = op->getOut();
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op = outvn->loneDescend();
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while(op != (PcodeOp *)0) {
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OpCode opc = op->code();
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if (opc == CPUI_INT_ADD) {
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int4 slot = op->getSlot(outvn);
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extra += getConstOffsetBack(op->getIn(1-slot),submultiplier,DEPTH_LIMIT); // Get any constants from other input
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if (submultiplier > multiplier)
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multiplier = submultiplier;
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}
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else if (opc == CPUI_PTRSUB) {
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extra += op->getIn(1)->getOffset();
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}
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else if (opc == CPUI_PTRADD) {
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if (op->getIn(0) != outvn) break;
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int8 ptraddmult = op->getIn(2)->getOffset();
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Varnode *invn = op->getIn(1);
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if (invn->isConstant()) // Only contribute to the extra
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extra += ptraddmult * (int8)invn->getOffset(); // if the index is constant
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getConstOffsetBack(invn,submultiplier,DEPTH_LIMIT); // otherwise just contribute to multiplier
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submultiplier *= ptraddmult;
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if (submultiplier > multiplier)
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multiplier = submultiplier;
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}
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else {
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break;
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}
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outvn = op->getOut();
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op = outvn->loneDescend();
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}
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extra = sign_extend(extra, 8*outvn->getSize()-1);
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extra &= calc_mask(outvn->getSize());
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return extra;
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}
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/// \brief Remove any constants in the additive expression rooted at the given PcodeOp
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///
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/// Walking recursively through the expression, any INT_ADD with a constant input is converted to
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/// a COPY. The INT_ADD must only contribute to the root expression.
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/// \param op is the given root PcodeOp
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/// \param slot is the input slot to walk back from
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/// \param maxLevel is the maximum depth to recurse
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/// \param data is the function containing the expression
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/// \return the sum of all constants that are removed
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int8 RulePtrsubUndo::removeLocalAddRecurse(PcodeOp *op,int4 slot,int4 maxLevel,Funcdata &data)
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{
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Varnode *vn = op->getIn(slot);
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if (!vn->isWritten())
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return 0;
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if (vn->loneDescend() != op)
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return 0; // Varnode must not be used anywhere else
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maxLevel -= 1;
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if (maxLevel < 0)
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return 0;
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op = vn->getDef();
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int8 retval = 0;
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if (op->code() == CPUI_INT_ADD) {
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if (op->getIn(1)->isConstant()) {
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retval += (int8)op->getIn(1)->getOffset();
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data.opRemoveInput(op, 1);
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data.opSetOpcode(op, CPUI_COPY);
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}
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else {
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retval += removeLocalAddRecurse(op, 0, maxLevel, data);
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retval += removeLocalAddRecurse(op, 1, maxLevel, data);
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}
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}
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return retval;
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}
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/// \brief Remove constants in the additive expression involving the given Varnode
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///
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/// Any additional PTRADD, PTRSUB, or INT_ADD that uses the Varnode and adds a constant is converted
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/// to a COPY. Additionally any other INT_ADD involved in the expression that adds a constant is
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/// also converted to COPY.
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/// \param vn is the given Varnode
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/// \param data is the function containing the expression
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/// \return the sum of all constants that are removed
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int8 RulePtrsubUndo::removeLocalAdds(Varnode *vn,Funcdata &data)
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{
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int8 extra = 0;
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PcodeOp *op = vn->loneDescend();
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while(op != (PcodeOp *)0) {
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OpCode opc = op->code();
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if (opc == CPUI_INT_ADD) {
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int4 slot = op->getSlot(vn);
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if (slot == 0 && op->getIn(1)->isConstant()) {
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extra += (int8)op->getIn(1)->getOffset();
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data.opRemoveInput(op, 1);
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data.opSetOpcode(op, CPUI_COPY);
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}
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else {
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extra += removeLocalAddRecurse(op,1-slot,DEPTH_LIMIT, data); // Get any constants from other input
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}
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}
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else if (opc == CPUI_PTRSUB) {
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extra += op->getIn(1)->getOffset();
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op->clearStopTypePropagation();
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data.opRemoveInput(op, 1);
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data.opSetOpcode(op, CPUI_COPY);
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}
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else if (opc == CPUI_PTRADD) {
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if (op->getIn(0) != vn) break;
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int8 ptraddmult = op->getIn(2)->getOffset();
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Varnode *invn = op->getIn(1);
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if (invn->isConstant()) {
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extra += ptraddmult * (int8)invn->getOffset();
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data.opRemoveInput(op,2);
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data.opRemoveInput(op,1);
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data.opSetOpcode(op, CPUI_COPY);
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}
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}
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else {
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break;
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}
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vn = op->getOut();
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op = vn->loneDescend();
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}
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return extra;
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}
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int4 RulePtrsubUndo::applyOp(PcodeOp *op,Funcdata &data)
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{
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if (!data.hasTypeRecoveryStarted()) return 0;
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Varnode *basevn = op->getIn(0);
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if (basevn->getTypeReadFacing(op)->isPtrsubMatching(op->getIn(1)->getOffset()))
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Varnode *cvn = op->getIn(1);
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int8 val = cvn->getOffset();
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int8 multiplier;
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int8 extra = getExtraOffset(op,multiplier);
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if (basevn->getTypeReadFacing(op)->isPtrsubMatching(val,extra,multiplier))
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return 0;
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data.opSetOpcode(op,CPUI_INT_ADD);
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op->clearStopTypePropagation();
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extra = removeLocalAdds(op->getOut(),data);
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if (extra != 0) {
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val = val + extra; // Lump extra into additive offset
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data.opSetInput(op,data.newConstant(cvn->getSize(), val & calc_mask(cvn->getSize())),1);
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}
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return 1;
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}
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