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Code Issues Releases Wiki Activity

Roughed in alias block option

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This commit is contained in:
caheckman 2020-02-24 09:23:05 -05:00
parent e4084b40ee
commit 04b4011166
5 changed files with 51 additions and 2 deletions
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1
Ghidra/Features/Decompiler/src/decompile/cpp/architecture.cc
View file

@ -96,6 +96,7 @@ Architecture::Architecture(void)
infer_pointers = true;
funcptr_align = 0;
flowoptions = 0;
alias_block_level = 2; // Block structs and arrays by default
defaultfp = (ProtoModel *)0;
defaultReturnAddr.space = (AddrSpace *)0;
evalfp_current = (ProtoModel *)0;

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

@ -130,6 +130,7 @@ public:
vector<AddrSpace *> inferPtrSpaces; ///< Set of address spaces in which a pointer constant is inferable
int4 funcptr_align; ///< How many bits of alignment a function ptr has
uint4 flowoptions; ///< options passed to flow following engine
int4 alias_block_level; ///< Aliases blocked by 0=none, 1=struct, 2=array, 3=all
vector<Rule *> extra_pool_rules; ///< Extra rules that go in the main pool (cpu specific, experimental)
Database *symboltab; ///< Memory map of global variables and functions

31
Ghidra/Features/Decompiler/src/decompile/cpp/options.cc
View file

@ -784,3 +784,34 @@ string OptionToggleRule::apply(Architecture *glb,const string &p1,const string &
}
return res;
}
/// \class OptionAliasBlock
/// \brief Set how locked data-types on the stack affect alias heuristics
///
/// Stack analysis uses the following simple heuristic: a pointer is unlikely to reference (alias)
/// a stack location if there is a locked data-type between the pointer base and the location.
/// This option determines what kind of locked data-types \b block aliases in this way.
/// - none - no data-types will block an alias
/// - struct - only structure data-types will block an alias
/// - array - array data-types (and structure data-types) will block an alias
/// - all - all locked data-types will block an alias
string OptionAliasBlock::apply(Architecture *glb,const string &p1,const string &p2,const string &p3) const
{
if (p1.size() == 0)
throw ParseError("Must specify alias block level");
int4 oldVal = glb->alias_block_level;
if (p1 == "none")
glb->alias_block_level = 0;
else if (p1 == "struct")
glb->alias_block_level = 1;
else if (p1 == "array")
glb->alias_block_level = 2; // The default. Let structs and arrays block aliases
else if (p1 == "all")
glb->alias_block_level = 3;
else
throw ParseError("Unknown alias block level: "+p1);
if (oldVal == glb->alias_block_level)
return "Alias block level unchanged";
return "Alias block level set to " + p1;
}

6
Ghidra/Features/Decompiler/src/decompile/cpp/options.hh
View file

@ -258,4 +258,10 @@ public:
virtual string apply(Architecture *glb,const string &p1,const string &p2,const string &p3) const;
};
class OptionAliasBlock : public ArchOption {
public:
OptionAliasBlock(void) { name = "aliasblock"; } ///< Constructor
virtual string apply(Architecture *glb,const string &p1,const string &p2,const string &p3) const;
};
#endif

14
Ghidra/Features/Decompiler/src/decompile/cpp/varmap.cc
View file

@ -1084,6 +1084,7 @@ void ScopeLocal::markUnaliased(const vector<uintb> &alias)
if (rangemap == (EntryMap *)0) return;
list<SymbolEntry>::iterator iter,enditer;
int4 alias_block_level = glb->alias_block_level;
bool aliason = false;
uintb curalias=0;
int4 i=0;
@ -1107,8 +1108,17 @@ void ScopeLocal::markUnaliased(const vector<uintb> &alias)
aliason = false;
if (!aliason)
symbol->getScope()->setAttribute(symbol,Varnode::nolocalalias);
if (symbol->isTypeLocked())
aliason = false;
if (symbol->isTypeLocked() && alias_block_level != 0) {
if (alias_block_level == 3)
aliason = false; // For this level, all locked data-types block aliases
else {
type_metatype meta = symbol->getType()->getMetatype();
if (meta == TYPE_STRUCT)
aliason = false; // Only structures block aliases
else if (meta == TYPE_ARRAY && alias_block_level > 1)
aliason = false; // Only arrays (and structures) block aliases
}
}
}
}
}