/// <summary>
/// Split a block at address <paramref name="addr" />.
/// </summary>
/// <param name="block"></param>
/// <param name="addr"></param>
/// <returns></returns>
private RtlBlock SplitBlock(RtlBlock block, Address addr)
{
var newBlock = new RtlBlock(addr, string.Format("l{0:X}", addr))
{
IsValid = block.IsValid
};
sr.ICFG.Nodes.Add(newBlock);
newBlock.Instructions.AddRange(
block.Instructions.Where(r => r.Address >= addr).OrderBy(r => r.Address));
foreach (var de in blockMap.Where(d => d.Key >= addr && d.Value == block).ToList())
{
blockMap[de.Key] = newBlock;
}
block.Instructions.RemoveAll(r => r.Address >= addr);
var succs = sr.ICFG.Successors(block).ToArray();
foreach (var s in succs)
{
AddEdge(newBlock, s);
RemoveEdge(block, s);
}
AddEdge(block, newBlock);
return(newBlock);
}
/// <summary>
/// Build the weakly connected component for a cluster by following
/// both predecessors and successors in the graph. However, we never
/// follow the predecessors of nodes that are marked directly called,
/// and we never follow successors that are marked directly called
/// (tail calls).
/// </summary>
/// <param name="node"></param>
/// <param name="cluster"></param>
/// <param name="nodesLeft"></param>
private void BuildWCC(
RtlBlock node,
Cluster cluster,
HashSet <RtlBlock> nodesLeft)
{
nodesLeft.Remove(node);
cluster.Blocks.Add(node);
foreach (var s in sr.ICFG.Successors(node))
{
if (nodesLeft.Contains(s))
{
// Only add if successor is not CALLed.
if (!procedures.Contains(s.Address))
{
BuildWCC(s, cluster, nodesLeft);
}
}
}
if (!procedures.Contains(node.Address))
{
// Only backtrack through predecessors if the node
// is not CALLed.
foreach (var p in sr.ICFG.Predecessors(node))
{
if (nodesLeft.Contains(p))
{
BuildWCC(p, cluster, nodesLeft);
}
}
}
}
private void RemoveInvalidBlocks(ScanResults sr)
{
var revGraph = new DiGraph <RtlBlock>();
var invalid = new RtlBlock(null, "<invalid>");
revGraph.AddNode(invalid);
foreach (var b in sr.ICFG.Nodes)
{
revGraph.AddNode(b);
}
foreach (var b in sr.ICFG.Nodes)
{
foreach (var s in sr.ICFG.Successors(b))
{
revGraph.AddEdge(s, b);
}
if (!b.IsValid)
{
revGraph.AddEdge(invalid, b);
}
}
// Find the transitive closure of invalid nodes.
var invalidNodes = new DfsIterator <RtlBlock>(revGraph)
.PreOrder(invalid)
.ToList();
foreach (var n in invalidNodes.Where(nn => nn != invalid))
{
sr.ICFG.RemoveNode(n);
sr.DirectlyCalledAddresses.Remove(n.Address);
// Debug.Print("Removed invalid node {0}", n.Address); // commented out as this becomes very verbose.
}
}
private void AddNode(RtlBlock block)
{
if (!sr.ICFG.Nodes.Contains(block))
{
sr.ICFG.Nodes.Add(block);
}
}
public SliceState(BackwardSlicer slicer, RtlBlock block, int iInstr)
{
this.slicer = slicer;
this.block = block;
this.instrs = slicer.host.GetBlockInstructions(block).ToArray();
this.iInstr = iInstr;
DumpBlock(BackwardSlicer.trace.TraceVerbose);
}
private void RemoveBlockFromGraph(RtlBlock n)
{
//Debug.Print("Removing block: {0}", n.Address);
blocks.Nodes.Remove(n);
foreach (var i in n.Instructions)
{
RemoveDirectlyCalledAddress(i);
}
}
public BackwardSlicer(IBackWalkHost <RtlBlock, RtlInstruction> host, RtlBlock rtlBlock, ProcessorState state)
{
this.host = host;
this.rtlBlock = rtlBlock;
this.processorState = state;
this.worklist = new WorkList <SliceState>();
this.visited = new HashSet <RtlBlock>();
this.cmp = new ExpressionValueComparer();
this.simp = new ExpressionSimplifier(host.SegmentMap, new EvalCtx(), null);
}
public ISet <RtlBlock> GetAncestors(RtlBlock n)
{
var anc = new HashSet <RtlBlock>();
foreach (var p in blocks.Predecessors(n))
{
GetAncestorsAux(p, n, anc);
}
return(anc);
}
public HeuristicScanner(
IServiceProvider services,
Program program,
IRewriterHost host,
DecompilerEventListener eventListener)
{
this.Services = services;
this.program = program;
this.host = host;
this.storageBinder = program.Architecture.CreateFrame();
this.eventListener = eventListener;
this.invalidBlock = new RtlBlock(null !, "<invalid>");
this.binder = program.Architecture.CreateFrame();
}
/// <summary>
/// Start a slice by examining any variables in the indirect jump
/// <paramref name="indirectJump"/>, then start tracing instructions
/// backwards beginning at instruction <paramref name="iInstr"/> in <paramref name="block"/>.
/// </summary>
/// <remarks>
/// Any expressions discovered in this step become the "roots"
/// of the backward slice. These roots are kept in the `Live` collection.
/// </remarks>
/// <param name="block">Basic block of instructions.</param>
/// <param name="iInstr">Index into the instructions in <paramref name="block"/>.</param>
/// <param name="indirectJump">Expression containing the target of the indirect call or jump.</param>
/// <returns>If backward slicing should continue.</returns>
public bool Start(RtlBlock block, int iInstr, Expression indirectJump)
{
this.state = new SliceState(this, block, iInstr);
visited.Add(block);
if (state.Start(indirectJump))
{
worklist.Add(state);
return(true);
}
else
{
return(false);
}
}
private ISet <RtlBlock> GetAncestorsAux(
RtlBlock n,
RtlBlock orig,
ISet <RtlBlock> ancestors)
{
if (ancestors.Contains(n) || n == orig)
{
return(ancestors);
}
ancestors.Add(n);
foreach (var p in blocks.Predecessors(n))
{
GetAncestorsAux(p, orig, ancestors);
}
return(ancestors);
}
public SliceState CreateNew(RtlBlock block, Address addrSucc)
{
var state = new SliceState(this.slicer, block, 0)
{
JumpTableFormat = this.JumpTableFormat,
JumpTableIndex = this.JumpTableIndex,
JumpTableIndexInterval = this.JumpTableIndexInterval,
Live = new Dictionary <Expression, BackwardSlicerContext>(this.Live, this.Live.Comparer),
ccNext = this.ccNext,
invertCondition = this.invertCondition,
addrSucc = addrSucc,
blockCount = blockCount + 1
};
state.iInstr = state.instrs.Length - 1;
return(state);
}
/// <summary>
/// Build Shingle blocks from the graph. An instruction can only be
/// in one block at a time, so at each point in the graph where the
/// successors > 1 or the predecessors > 1, we create a new node.
/// </summary>
/// <param name="instructions"></param>
/// <returns></returns>
public IcfgBuilder BuildBlocks(DiGraph <Address> graph)
{
// Remember, the graph is backwards!
var activeBlocks = new List <RtlBlock>();
var allBlocks = new DiGraph <RtlBlock>();
var edges = new List <Tuple <RtlBlock, Address> >();
var mpBlocks = new Dictionary <Address, RtlBlock>();
var wl = sr.Instructions.Keys.ToSortedSet();
while (wl.Count > 0)
{
var addr = wl.First();
wl.Remove(addr);
var instr = sr.Instructions[addr];
var label = program.NamingPolicy.BlockName(addr);
var block = new RtlBlock(addr, label);
block.Instructions.Add(instr);
allBlocks.AddNode(block);
mpBlocks.Add(addr, block);
bool endBlockNow = false;
bool terminateDeferred = false;
bool addFallthroughEdge = false;
bool addFallthroughEdgeDeferred = false;
for (;;)
{
var addrInstrEnd = instr.Address + instr.Length;
if ((instr.Class & DT) != 0)
{
if (MayFallThrough(instr))
{
addFallthroughEdge = (instr.Class & DT) == T;
addFallthroughEdgeDeferred = (instr.Class & DT) == DT;
}
var addrDst = DestinationAddress(instr);
if (addrDst != null && (instr.Class & InstrClass.Call) == 0)
{
edges.Add(Tuple.Create(block, addrDst));
}
if ((instr.Class & DT) == DT)
{
terminateDeferred = true;
}
else
{
endBlockNow = true;
}
}
else if (instr.Class == InstrClass.Terminates)
{
endBlockNow = true;
addFallthroughEdge = false;
addFallthroughEdge = false;
}
else
{
endBlockNow = terminateDeferred;
addFallthroughEdge = addFallthroughEdgeDeferred;
addFallthroughEdgeDeferred = false;
}
if (sr.DirectlyCalledAddresses.Keys.Contains(addrInstrEnd) ||
sr.KnownProcedures.Contains(addrInstrEnd))
{
// If control falls into what looks like a procedure, don't
// add an edge.
addFallthroughEdge = false;
endBlockNow = true;
}
if (addFallthroughEdge)
{
edges.Add(Tuple.Create(block, addrInstrEnd));
}
if (endBlockNow ||
!wl.Contains(addrInstrEnd) ||
!graph.Nodes.Contains(addrInstrEnd) ||
graph.Successors(addrInstrEnd).Count != 1)
{
//Debug.Print("addr: {0}, end {1}, term: {2}, wl: {3}, nodes: {4}, succ: {5}",
// addr,
// addrInstrEnd,
// endBlockNow,
// !wl.Contains(addrInstrEnd),
// !graph.Nodes.Contains(addrInstrEnd),
// graph.Nodes.Contains(addrInstrEnd)
// ? graph.Successors(addrInstrEnd).Count
// : 0);
if (!endBlockNow && !addFallthroughEdge)
{
edges.Add(Tuple.Create(block, addrInstrEnd));
}
break;
}
wl.Remove(addrInstrEnd);
instr = sr.Instructions[addrInstrEnd];
block.Instructions.Add(instr);
endBlockNow = terminateDeferred;
}
}
return(new IcfgBuilder
{
Edges = edges,
AddrToBlock = mpBlocks,
Blocks = allBlocks,
});
}
/// <summary>
/// Recursively disassembles the range of addresses.
/// <paramref name="proc"/>.
/// </summary>
/// <param name="addr"></param>
/// <param name="proc"></param>
/// <returns></returns>
public RtlBlock Disassemble(Address addr)
{
var current = new RtlBlock(addr, string.Format("l{0:X}", addr));
var dasm = program.Architecture.CreateRewriter(
program.CreateImageReader(addr),
program.Architecture.CreateProcessorState(), //$TODO: use state from user.
binder,
host);
foreach (var instr in dasm.TakeWhile(i => isAddrValid(i.Address)))
{
RtlBlock block;
if (blockMap.TryGetValue(instr.Address, out block))
{
// This instruction was already disassembled before.
if (instr.Address.ToLinear() != block.Address.ToLinear())
{
block = SplitBlock(block, instr.Address);
}
if (current.Instructions.Count == 0)
{
// Coincides exactly, return the old block.
return(block);
}
else
{
// Fell into 'block' while disassembling
// 'current'. Create a fall-though edge
if (!sr.ICFG.Nodes.Contains(current))
{
AddNode(current);
}
AddEdge(current, block);
return(current);
}
}
else
{
// Fresh instruction
AddNode(current);
current.Instructions.Add(instr);
blockMap.Add(instr.Address, current);
Address addrOp;
switch (instr.Class)
{
case RtlClass.Invalid:
case RtlClass.None:
current.IsValid = false;
return(current);
case RtlClass.Linear:
case RtlClass.Linear | RtlClass.Conditional:
if (FallthroughToInvalid(instr))
{
current.IsValid = false;
return(current);
}
break;
case RtlClass.Transfer | RtlClass.Call:
addrOp = DestinationAddress(instr);
if (addrOp != null)
{
if (program.SegmentMap.IsValidAddress(addrOp))
{
int c;
if (!sr.DirectlyCalledAddresses.TryGetValue(addrOp, out c))
{
c = 0;
}
sr.DirectlyCalledAddresses[addrOp] = c + 1;
}
else
{
current.IsValid = false;
}
}
if (FallthroughToInvalid(instr))
{
current.IsValid = false;
return(current);
}
// If assume calls terminate, stop scanning.
if (assumeCallsDiverge)
{
return(current);
}
block = Disassemble(instr.Address + instr.Length);
AddEdge(current, block);
return(current);
case RtlClass.Transfer:
addrOp = DestinationAddress(instr);
if (addrOp != null)
{
if (isAddrValid(addrOp))
{
block = Disassemble(addrOp);
AddEdge(current, block);
return(current);
}
else
{
// Very verbose debugging statement disabled to speed up Reko.
//Debug.Print("{0} jumps to invalid address", instr.Address);
current.IsValid = false;
}
return(current);
}
return(current);
case RtlClass.Transfer | RtlClass.Conditional:
FallthroughToInvalid(instr);
addrOp = DestinationAddress(instr);
if (addrOp != null && program.SegmentMap.IsValidAddress(addrOp))
{
block = Disassemble(addrOp);
Debug.Assert(sr.ICFG.Nodes.Contains(block));
AddEdge(current, block);
}
block = Disassemble(instr.Address + instr.Length);
AddEdge(current, block);
return(current);
default:
throw new NotImplementedException(
string.Format(
"RTL class {0}.",
instr.Class));
}
}
}
AddNode(current);
return(current);
}
private void RemoveEdge(RtlBlock from, RtlBlock to)
{
sr.ICFG.RemoveEdge(from, to);
}
private void AddEdge(RtlBlock from, RtlBlock to)
{
sr.ICFG.AddEdge(from, to);
}
public RtlProcedure(RtlBlock entry, ISet <RtlBlock> blocks)
{
this.Entry = entry;
this.Blocks = blocks;
}
/// <summary>
/// Splits a multiple entry cluster into separate sub-clusters by
/// partitioning all the blocks into subsets where each subset is
/// dominated by one of the original entries.
/// </summary>
/// <remarks>
/// Many binaries contain cross-procedure jumps. If the target of
/// those jumps is a single block with no successors, it is very
/// likely an instance of a "shared exit node" pattern that many
/// compilers+linkers emit. We handle that case separately.
/// </remarks>
/// <param name="cluster"></param>
/// <returns></returns>
public List <RtlProcedure> PartitionIntoSubclusters(Cluster cluster)
{
// Create a fake node that will serve as the parent of all the
// existing entries. That node will be used to compute all
// immediate dominators of all reachable blocks.
var auxNode = new RtlBlock(null, "<root>");
sr.ICFG.AddNode(auxNode);
var allEntries =
cluster.Entries.Concat(
cluster.Blocks
.Where(b => sr.ICFG.Predecessors(b).Count == 0))
.Distinct()
.OrderBy(b => b.Address)
.ToList();
foreach (var entry in allEntries)
{
sr.ICFG.AddEdge(auxNode, entry);
}
var idoms = LTDominatorGraph <RtlBlock> .Create(sr.ICFG, auxNode);
// DumpDominatorTrees(idoms);
// Find all nodes whose immediate dominator is "<root>".
// Those are the entries to new clusters and may contain blocks
// that are shared between procedures in the source program.
var newEntries = cluster.Blocks.Where(b => idoms[b] == auxNode).ToList();
var dominatedEntries = newEntries.ToDictionary(k => k, v => new HashSet <RtlBlock> {
v
});
// Partition the nodes in the cluster into categories depending on which
// one of the newEntries they are dominated by.
foreach (var b in cluster.Blocks)
{
if (dominatedEntries.ContainsKey(b))
{
continue; // already there.
}
var n = b;
for (;;)
{
var i = idoms[n];
if (i == null)
{
break;
}
if (dominatedEntries.ContainsKey(i))
{
// If my idom is already in the set, add me too.
dominatedEntries[i].Add(b);
break;
}
n = i;
}
}
// Now remove the fake node
sr.ICFG.RemoveNode(auxNode);
// Handle the special case with new entries that weren't there before,
// and only consist of a linear sequence of blocks. Mark such nodes as "shared".
// Later stages will copy these nodes into their respective procedures.
foreach (var newEntry in dominatedEntries.Keys
.Where(e => !cluster.Entries.Contains(e)).ToList())
{
if (sr.ICFG.Successors(newEntry).Count == 0)
{
newEntry.IsSharedExitBlock = true;
dominatedEntries.Remove(newEntry);
}
}
return(dominatedEntries
.OrderBy(e => e.Key.Address)
.Select(e => new RtlProcedure(e.Key, e.Value))
.ToList());
}
/// <summary>
/// Starting at <paramref name="start"/>
/// </summary>
/// <param name="start"></param>
/// <returns></returns>
public List <RtlBlock> LinearSequence(RtlBlock start)
{
return(new List <RtlBlock>());
}
private void RemoveBlockFromGraph(RtlBlock n)
{
//Debug.Print("Removing block: {0}", n.Address);
blocks.Nodes.Remove(n);
}
