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GP-2018 Label zero offset stack pointer references

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This commit is contained in:
caheckman 2022-05-13 14:26:12 -04:00
parent e3a751ca46
commit 96b92e2c12
3 changed files with 34 additions and 2 deletions
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6
Ghidra/Features/Decompiler/src/decompile/cpp/ruleaction.cc
View file

@ -4181,9 +4181,11 @@ int4 RuleSubCommute::applyOp(PcodeOp *op,Funcdata &data)
break;
}
case CPUI_INT_ADD:
if (offset != 0) return 0; // Only commutes with least significant SUBPIECE
if (longform->getIn(0)->isSpacebase()) return 0; // Deconflict with RulePtrArith
break;
case CPUI_INT_MULT:
// These only commute with least significant SUBPIECE
if (offset != 0) return 0;
if (offset != 0) return 0; // Only commutes with least significant SUBPIECE
break;
// Bitwise ops, type of subpiece doesnt matter
case CPUI_INT_NEGATE:

29
Ghidra/Features/Decompiler/src/decompile/cpp/varmap.cc
View file

@ -306,6 +306,33 @@ void ScopeLocal::collectNameRecs(void)
}
}
/// For any read of the input stack pointer by a non-additive p-code op, assume this constitutes a
/// a zero offset reference into the stack frame. Replace the raw Varnode with the standard
/// spacebase placeholder, PTRSUB(sp,#0), so that the data-type system can treat it as a reference.
void ScopeLocal::annotateRawStackPtr(void)
{
if (!fd->isTypeRecoveryOn()) return;
Varnode *spVn = fd->findSpacebaseInput(space);
if (spVn == (Varnode *)0) return;
list<PcodeOp *>::const_iterator iter;
vector<PcodeOp *> refOps;
for(iter=spVn->beginDescend();iter!=spVn->endDescend();++iter) {
PcodeOp *op = *iter;
if (op->getEvalType() == PcodeOp::special && !op->isCall()) continue;
OpCode opc = op->code();
if (opc == CPUI_INT_ADD || opc == CPUI_PTRSUB || opc == CPUI_PTRADD)
continue;
refOps.push_back(op);
}
for(int4 i=0;i<refOps.size();++i) {
PcodeOp *op = refOps[i];
int4 slot = op->getSlot(spVn);
PcodeOp *ptrsub = fd->newOpBefore(op,CPUI_PTRSUB,spVn,fd->newConstant(spVn->getSize(),0));
fd->opSetInput(op, ptrsub->getOut(), slot);
}
}
/// This resets the discovery process for new local variables mapped to the scope's address space.
/// Any analysis removing specific ranges from the mapped set (via markNotMapped()) is cleared.
void ScopeLocal::resetLocalWindow(void)
@ -1024,6 +1051,8 @@ void ScopeLocal::restructureVarnode(bool aliasyes)
state.sortAlias();
if (aliasyes)
markUnaliased(state.getAlias());
if (!state.getAlias().empty() && state.getAlias()[0] == 0) // If a zero offset use of the stack pointer exists
annotateRawStackPtr(); // Add a special placeholder PTRSUB
}
/// Define stack Symbols based on HighVariables.

1
Ghidra/Features/Decompiler/src/decompile/cpp/varmap.hh
View file

@ -208,6 +208,7 @@ class ScopeLocal : public ScopeInternal {
void fakeInputSymbols(void); ///< Make sure all stack inputs have an associated Symbol
void addRecommendName(Symbol *sym); ///< Convert the given symbol to a name recommendation
void collectNameRecs(void); ///< Collect names of unlocked Symbols on the stack
void annotateRawStackPtr(void); ///< Generate placeholder PTRSUB off of stack pointer
public:
ScopeLocal(uint8 id,AddrSpace *spc,Funcdata *fd,Architecture *g); ///< Constructor
virtual ~ScopeLocal(void) {} ///< Destructor