// implements < , <= causes failures when used to sort Windows vectors
bool vectorSort(SliceNode::Ptr ptr1, SliceNode::Ptr ptr2) {
AssignmentPtr assign1 = ptr1->assign();
AssignmentPtr assign2 = ptr2->assign();
if (!assign2) return false;
else if (!assign1) return true;
Address addr1 = assign1->addr();
Address addr2 = assign2->addr();
if (addr1 == addr2) {
AbsRegion &out1 = assign1->out();
AbsRegion &out2 = assign2->out();
return out1 < out2;
} else {
return addr1 < addr2;
}
}
void BoundFactsCalculator::CalcTransferFunction(Node::Ptr curNode, BoundFact *newFact){
SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);
if (!node->assign()) return;
if (node->assign() && node->assign()->out().absloc().type() == Absloc::Register &&
(node->assign()->out().absloc().reg() == x86::zf || node->assign()->out().absloc().reg() == x86_64::zf)) {
// zf should be only predecessor of this node
parsing_printf("\t\tThe predecessor node is zf assignment!\n");
newFact->SetPredicate(node->assign(), ExpandAssignment(node->assign()) );
return;
}
entryID id = node->assign()->insn()->getOperation().getID();
// The predecessor is not a conditional jump,
// then we can determine buond fact based on the src assignment
parsing_printf("\t\tThe predecessor node is normal node\n");
parsing_printf("\t\t\tentry id %d\n", id);
AbsRegion &ar = node->assign()->out();
Instruction::Ptr insn = node->assign()->insn();
pair<AST::Ptr, bool> expandRet = ExpandAssignment(node->assign());
if (expandRet.first == NULL) {
parsing_printf("\t\t\t No semantic support for this instruction. Assume it does not affect jump target calculation. Ignore it (Treat as identity function) except for ptest. ptest should kill the current predicate\n");
if (id == e_ptest) {
parsing_printf("\t\t\t\tptest instruction, kill predciate.\n");
newFact->pred.valid = false;
}
return;
} else {
parsing_printf("\tAST: %s\n", expandRet.first->format().c_str());
}
AST::Ptr calculation = expandRet.first;
BoundCalcVisitor bcv(*newFact, node->block(), handleOneByteRead);
calculation->accept(&bcv);
AST::Ptr outAST;
// If the instruction writes memory,
// we need the AST that represents the memory access and the address.
// When the AbsRegion represents memory,
// the generator of the AbsRegion is set to be the AST that represents
// the memory address during symbolic expansion.
// In other cases, if the AbsRegion represents a register,
// the generator is not set.
if (ar.generator() != NULL)
outAST = SimplifyAnAST(RoseAST::create(ROSEOperation(ROSEOperation::derefOp, ar.size()), ar.generator()), node->assign()->insn()->size());
else
outAST = VariableAST::create(Variable(ar));
/*
* Naively, bsf and bsr produces a bound from 0 to the number of bits of the source operands.
* In pratice, especially in libc, the real bound is usually smaller than the size of the source operand.
* Ex 1: shl %cl,%edx
* bsf %rdx,%rcx
* Here rcx is in range [0,31] rather than [0,63] even though rdx has 64 bits.
*
* Ex 2: pmovmskb %xmm0,%edx
* bsf %rdx, %rdx
* Here rdx is in range[0,15] because pmovmskb only sets the least significat 16 bits
* In addition, overapproximation of the bound can lead to bogus control flow
* that causes overlapping blocks or function.
* It is important to further anaylze the operand in bsf rather than directly conclude the bound
if (id == e_bsf || id == e_bsr) {
int size = node->assign()->insn()->getOperand(0).getValue()->size();
newFact->GenFact(outAST, new BoundValue(StridedInterval(1,0, size * 8 - 1)), false);
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
return;
}
*/
if (id == e_xchg) {
newFact->SwapFact(calculation, outAST);
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
return;
}
if (id == e_push) {
if (calculation->getID() == AST::V_ConstantAST) {
ConstantAST::Ptr c = boost::static_pointer_cast<ConstantAST>(calculation);
newFact->PushAConst(c->val().val);
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
return;
}
}
if (id == e_pop) {
if (newFact->PopAConst(outAST)) {
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
return;
}
}
// Assume all SETxx entry ids are contiguous
if (id >= e_setb && id <= e_setz) {
newFact->GenFact(outAST, new BoundValue(StridedInterval(1,0,1)), false);
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
return;
}
if (bcv.IsResultBounded(calculation)) {
parsing_printf("\t\t\tGenerate bound fact for %s\n", outAST->format().c_str());
newFact->GenFact(outAST, new BoundValue(*bcv.GetResultBound(calculation)), false);
}
else {
parsing_printf("\t\t\tKill bound fact for %s\n", outAST->format().c_str());
newFact->KillFact(outAST, false);
}
if (calculation->getID() == AST::V_VariableAST) {
// We only track alising between registers
parsing_printf("\t\t\t%s and %s are equal\n", calculation->format().c_str(), outAST->format().c_str());
newFact->InsertRelation(calculation, outAST, BoundFact::Equal);
}
newFact->AdjustPredicate(outAST, calculation);
// Now try to track all aliasing.
// Currently, all variables in the slice are presented as an AST
// consists of input variables to the slice (the variables that
// we do not the sources of their values).
newFact->TrackAlias(DeepCopyAnAST(calculation), outAST);
// Apply tracking relations to the calculation to generate a
// potentially stricter bound
BoundValue *strictValue = newFact->ApplyRelations(outAST);
if (strictValue != NULL) {
parsing_printf("\t\t\tGenerate stricter bound fact for %s\n", outAST->format().c_str());
newFact->GenFact(outAST, strictValue, false);
}
parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
newFact->Print();
}
BoundFact* BoundFactsCalculator::Meet(Node::Ptr curNode) {
SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);
EdgeIterator gbegin, gend;
curNode->ins(gbegin, gend);
BoundFact* newFact = NULL;
bool first = true;
for (; gbegin != gend; ++gbegin) {
TypedSliceEdge::Ptr edge = boost::static_pointer_cast<TypedSliceEdge>(*gbegin);
SliceNode::Ptr srcNode = boost::static_pointer_cast<SliceNode>(edge->source());
BoundFact *prevFact = GetBoundFactOut(srcNode);
bool newCopy = false;
if (prevFact == NULL) {
parsing_printf("\t\tIncoming node %lx has not been calculated yet, ignore it\n", srcNode->addr());
continue;
} else {
// Otherwise, create a new copy.
// We do not want to overwrite the bound fact
// of the predecessor
prevFact = new BoundFact(*prevFact);
newCopy = true;
}
parsing_printf("\t\tMeet incoming edge from %lx\n", srcNode->addr());
parsing_printf("\t\tThe fact from %lx before applying transfer function\n", srcNode->addr());
prevFact->Print();
if (!srcNode->assign()) {
prevFact = new BoundFact(*prevFact);
newCopy = true;
parsing_printf("\t\tThe predecessor node is the virtual entry ndoe\n");
if (firstBlock) {
// If the indirect jump is in the entry block
// of the function, we assume that rax is in
// range [0,8] for analyzing the movaps table.
// NEED TO HAVE A SAFE WAY TO DO THIS!!
parsing_printf("\t\tApplying entry block rax assumption!\n");
AST::Ptr axAST;
if (func->entry()->obj()->cs()->getAddressWidth() == 8)
axAST = VariableAST::create(Variable(AbsRegion(Absloc(x86_64::rax))));
else
// DOES THIS REALLY SHOW UP IN 32-BIT CODE???
axAST = VariableAST::create(Variable(AbsRegion(Absloc(x86::eax))));
prevFact->GenFact(axAST, new BoundValue(StridedInterval(1,0,8)), false);
}
} else if (srcNode->assign() && IsConditionalJump(srcNode->assign()->insn())) {
prevFact = new BoundFact(*prevFact);
newCopy = true;
// If the predecessor is a conditional jump,
// we can determine bound fact based on the predicate and the edge type
parsing_printf("\t\tThe predecessor node is a conditional jump!\n");
if (!prevFact->ConditionalJumpBound(srcNode->assign()->insn(), edge->type())) {
fprintf(stderr, "From %lx to %lx\n", srcNode->addr(), node->addr());
assert(0);
}
}
ThunkBound(prevFact, srcNode, node, newCopy);
parsing_printf("\t\tFact from %lx after applying transfer function\n", srcNode->addr());
prevFact->Print();
if (first) {
// For the first incoming dataflow fact,
// we just copy it.
// We can do this because if an a-loc
// is missing in the fact map, we assume
// the a-loc is top.
first = false;
if (newCopy) newFact = prevFact; else newFact = new BoundFact(*prevFact);
} else {
newFact->Meet(*prevFact);
if (newCopy) delete prevFact;
}
}
return newFact;
}
bool BoundFactsCalculator::CalculateBoundedFacts() {
/* We use a dataflow analysis to calculate the value bound
* of each register and potentially some memory locations.
* The key steps of the dataflow analysis are
* 1. Determine the analysis order:
* First calculate all strongly connected components (SCC)
* of the graph. The flow analysis inside a SCC is
* iterative. The flow analysis between several SCCs
* is done topologically.
* 2. For each node, need to calculate the meet and
* calculate the transfer function.
* 1. The meet should be simply an intersection of all the bounded facts
* along all paths.
* 2. To calculate the transfer function, we first get the symbolic expression
* of the instrution for the node. Then depending on the instruction operation
* and the meet result, we know what are still bounded. For example, loading
* memory is always unbounded; doing and operation on a register with a constant
* makes the register bounded.
*/
DetermineAnalysisOrder();
queue<Node::Ptr> workingList;
unordered_set<Node::Ptr, Node::NodePtrHasher> inQueue;
unordered_map<Node::Ptr, int, Node::NodePtrHasher> inQueueLimit;
for (int curOrder = 0; curOrder <= orderStamp; ++curOrder) {
// We first determine which nodes are
// in this SCC
vector<Node::Ptr> curNodes;
NodeIterator nbegin, nend;
slice->allNodes(nbegin, nend);
for (; nbegin != nend; ++nbegin) {
if (analysisOrder[*nbegin] == curOrder) {
curNodes.push_back(*nbegin);
workingList.push(*nbegin);
inQueue.insert(*nbegin);
}
}
if (!HasIncomingEdgesFromLowerLevel(curOrder, curNodes)) {
// If this SCC is an entry SCC,
// we choose a node inside the SCC
// and let it be top.
// This should only contain the virtual entry node
parsing_printf("This SCC does not incoming edges from outside\n");
boundFactsIn[curNodes[0]] = new BoundFact();
boundFactsOut[curNodes[0]] = new BoundFact();
}
parsing_printf("Starting analysis inside SCC %d\n", curOrder);
// We now start iterative analysis inside the SCC
while (!workingList.empty()) {
// We get the current node
Node::Ptr curNode = workingList.front();
workingList.pop();
inQueue.erase(curNode);
SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);
++inQueueLimit[curNode];
if (inQueueLimit[curNode] > IN_QUEUE_LIMIT) continue;
BoundFact* oldFactIn = GetBoundFactIn(curNode);
parsing_printf("Calculate Meet for %lx", node->addr());
if (node->assign()) {
parsing_printf(", insn: %s\n", node->assign()->insn()->format().c_str());
}
else {
if (node->block() == NULL)
parsing_printf(", the VirtualExit node\n");
else
parsing_printf(", the VirtualEntry node\n");
}
parsing_printf("\tOld fact for %lx:\n", node->addr());
if (oldFactIn == NULL) parsing_printf("\t\t do not exist\n"); else oldFactIn->Print();
// We find all predecessors of the current node
// and calculates the union of the analysis results
// from the predecessors
BoundFact* newFactIn = Meet(curNode);
parsing_printf("\tNew fact at %lx\n", node->addr());
if (newFactIn != NULL) newFactIn->Print(); else parsing_printf("\t\tNot calculated\n");
// If the current node has not been calcualted yet,
// or the new meet results are different from the
// old ones, we keep the new results
if (newFactIn != NULL && (oldFactIn == NULL || *oldFactIn != *newFactIn)) {
parsing_printf("\tFacts change!\n");
if (oldFactIn != NULL) delete oldFactIn;
boundFactsIn[curNode] = newFactIn;
BoundFact* newFactOut = new BoundFact(*newFactIn);
// The current node has a transfer function
// that changes the analysis results
CalcTransferFunction(curNode, newFactOut);
if (boundFactsOut.find(curNode) != boundFactsOut.end() && boundFactsOut[curNode] != NULL)
delete boundFactsOut[curNode];
boundFactsOut[curNode] = newFactOut;
curNode->outs(nbegin, nend);
for (; nbegin != nend; ++nbegin)
// We only add node inside current SCC into the working list
if (inQueue.find(*nbegin) == inQueue.end() && analysisOrder[*nbegin] == curOrder) {
workingList.push(*nbegin);
inQueue.insert(*nbegin);
}
} else {
if (newFactIn != NULL) delete newFactIn;
parsing_printf("\tFacts do not change!\n");
}
}
}
return true;
}
SymEval::Retval_t SymEval::process(SliceNode::Ptr ptr,
Result_t &dbase,
std::set<Edge::Ptr> &skipEdges) {
bool failedTranslation;
bool skippedEdge = false;
bool skippedInput = false;
bool success = false;
std::map<const AbsRegion*, std::set<Assignment::Ptr> > inputMap;
expand_cerr << "Calling process on " << ptr->format() << endl;
// Don't try an expansion of a widen node...
if (!ptr->assign()) return WIDEN_NODE;
EdgeIterator begin, end;
ptr->ins(begin, end);
for (; begin != end; ++begin) {
SliceEdge::Ptr edge = boost::static_pointer_cast<SliceEdge>(*begin);
SliceNode::Ptr source = boost::static_pointer_cast<SliceNode>(edge->source());
// Skip this one to break a cycle.
if (skipEdges.find(edge) != skipEdges.end()) {
expand_cerr << "In process, skipping edge from "
<< source->format() << endl;
skippedEdge = true;
continue;
}
Assignment::Ptr assign = source->assign();
if (!assign) continue; // widen node
expand_cerr << "Assigning input " << edge->data().format()
<< " from assignment " << assign->format() << endl;
inputMap[&edge->data()].insert(assign);
}
expand_cerr << "\t Input map has size " << inputMap.size() << endl;
// All of the expanded inputs are in the parameter dbase
// If not (like this one), add it
AST::Ptr ast;
boost::tie(ast, failedTranslation) = SymEval::expand(ptr->assign());
// expand_cerr << "\t ... resulting in " << dbase.format() << endl;
// We have an AST. Now substitute in all of its predecessors.
for (std::map<const AbsRegion*, std::set<Assignment::Ptr> >::iterator iter = inputMap.begin();
iter != inputMap.end(); ++iter) {
// If we have multiple secondary definitions, we:
// if all definitions are equal, use the first
// otherwise, use nothing
AST::Ptr definition;
for (std::set<Assignment::Ptr>::iterator iter2 = iter->second.begin();
iter2 != iter->second.end(); ++iter2) {
AST::Ptr newDef = dbase[*iter2];
if (!definition) {
definition = newDef;
continue;
} else if (definition->equals(newDef)) {
continue;
} else {
// Not equal
definition = AST::Ptr();
skippedInput = true;
break;
}
}
// The region used by the current assignment...
const AbsRegion ® = *iter->first;
// Create an AST around this one
VariableAST::Ptr use = VariableAST::create(Variable(reg, ptr->addr()));
if (!definition) {
// Can happen if we're expanding out of order, and is generally harmless.
continue;
}
expand_cerr << "Before substitution: " << (ast ? ast->format() : "<NULL AST>") << endl;
if (!ast) {
expand_cerr << "Skipping substitution because of null AST" << endl;
} else {
ast = AST::substitute(ast, use, definition);
success = true;
}
expand_cerr << "\t result is " << (ast ? ast->format() : "<NULL AST>") << endl;
}
expand_cerr << "Result of substitution: " << ptr->assign()->format() << " == "
<< (ast ? ast->format() : "<NULL AST>") << endl;
// And attempt simplification again
ast = simplifyStack(ast, ptr->addr(), ptr->func(), ptr->block());
expand_cerr << "Result of post-substitution simplification: " << ptr->assign()->format() << " == "
<< (ast ? ast->format() : "<NULL AST>") << endl;
dbase[ptr->assign()] = ast;
if (failedTranslation) return FAILED_TRANSLATION;
else if (skippedEdge || skippedInput) return SKIPPED_INPUT;
else if (success) return SUCCESS;
else return FAILED;
}
// Do the previous, but use a Graph as a guide for
// performing forward substitution on the AST results
SymEval::Retval_t SymEval::expand(Dyninst::Graph::Ptr slice, DataflowAPI::Result_t &res) {
bool failedTranslation = false;
bool skippedInput = false;
//cout << "Calling expand" << endl;
// Other than the substitution this is pretty similar to the first example.
NodeIterator gbegin, gend;
slice->allNodes(gbegin, gend);
// First, we'll sort the nodes in some deterministic order so that the loop removal
// is deterministic
std::vector<SliceNode::Ptr> sortVector;
for ( ; gbegin != gend; ++gbegin) {
Node::Ptr ptr = *gbegin;
expand_cerr << "pushing " << (*gbegin)->format() << " to sortVector" << endl;
SliceNode::Ptr cur = boost::static_pointer_cast<SliceNode>(ptr);
sortVector.push_back(cur);
}
std::stable_sort(sortVector.begin(), sortVector.end(), vectorSort);
// Optimal ordering of search
ExpandOrder worklist;
std::queue<Node::Ptr> dfs_worklist;
std::vector<SliceNode::Ptr>::iterator vit = sortVector.begin();
for ( ; vit != sortVector.end(); ++vit) {
SliceNode::Ptr ptr = *vit;
Node::Ptr cur = boost::static_pointer_cast<Node>(ptr);
dfs_worklist.push(cur);
}
/* First, we'll do DFS to check for circularities in the graph;
* if so, mark them so we don't do infinite substitution */
std::map<Node::Ptr, int> state;
while (!dfs_worklist.empty()) {
Node::Ptr ptr = dfs_worklist.front();
dfs_worklist.pop();
dfs(ptr, state, worklist.skipEdges());
}
slice->allNodes(gbegin, gend);
for (; gbegin != gend; ++gbegin) {
expand_cerr << "adding " << (*gbegin)->format() << " to worklist" << endl;
Node::Ptr ptr = *gbegin;
SliceNode::Ptr sptr =
boost::static_pointer_cast<SliceNode>(ptr);
worklist.insert(sptr,false);
}
/* have a list
* for each node, process
* if processessing succeeded, remove the element
* if the size of the list has changed, continue */
while (1) {
SliceNode::Ptr aNode;
int order;
boost::tie(aNode,order) = worklist.pop_next();
if (order == -1) // empty
break;
if (!aNode->assign()) {
worklist.mark_done(aNode);
continue; // Could be a widen point
}
expand_cerr << "Visiting node " << aNode->assign()->format()
<< " order " << order << endl;
if (order != 0) {
cerr << "ERROR: order is non zero: " << order << endl;
}
assert(order == 0); // there are no loops
AST::Ptr prev = res[aNode->assign()];
Retval_t result = process(aNode, res, worklist.skipEdges());
AST::Ptr post = res[aNode->assign()];
switch (result) {
case FAILED:
return FAILED;
break;
case WIDEN_NODE:
// Okay...
break;
case FAILED_TRANSLATION:
failedTranslation = true;
break;
case SKIPPED_INPUT:
skippedInput = true;
break;
case SUCCESS:
break;
}
// We've visited this node, freeing its children
// to be visited in turn
worklist.mark_done(aNode);
if (post && !(post->equals(prev))) {
expand_cerr << "Adding successors to list, as new expansion " << endl
<< "\t" << post->format() << endl
<< " != " << endl
<< "\t" << (prev ? prev->format() : "<NULL>") << endl;
EdgeIterator oB, oE;
aNode->outs(oB, oE);
for (; oB != oE; ++oB) {
if(worklist.skipEdges().find(*oB) == worklist.skipEdges().end()) {
SliceNode::Ptr out =
boost::static_pointer_cast<SliceNode>(
(*oB)->target());
worklist.insert(out);
}
}
}
}
if (failedTranslation) return FAILED_TRANSLATION;
else if (skippedInput) return SKIPPED_INPUT;
else return SUCCESS;
}