Ejemplo n.º 1
0
        /// <summary>
        /// Processes procedures individually, building complex expression
        /// trees out of the simple, close-to-the-machine code generated by
        /// the disassembly.
        /// </summary>
        /// <param name="rl"></param>
        public void BuildExpressionTrees()
        {
            eventListener.ShowProgress("Building expressions.", 0, program.Procedures.Count);
            foreach (var sst in this.ssts)
            {
                var ssa = sst.SsaState;
                try
                {
                    DumpWatchedProcedure("Before expression coalescing", ssa.Procedure);

                    // Procedures should be untangled from each other. Now process
                    // each one separately.
                    DeadCode.Eliminate(ssa);

                    // Build expressions. A definition with a single use can be subsumed
                    // into the using expression.
                    var coa = new Coalescer(ssa);
                    coa.Transform();
                    DeadCode.Eliminate(ssa);

                    var vp = new ValuePropagator(program.SegmentMap, ssa, program.CallGraph, dynamicLinker, eventListener);
                    vp.Transform();

                    DumpWatchedProcedure("After expression coalescing", ssa.Procedure);

                    var liv = new LinearInductionVariableFinder(
                        ssa,
                        new BlockDominatorGraph(
                            ssa.Procedure.ControlGraph,
                            ssa.Procedure.EntryBlock));
                    liv.Find();

                    foreach (var de in liv.Contexts)
                    {
                        var str = new StrengthReduction(ssa, de.Key, de.Value);
                        str.ClassifyUses();
                        str.ModifyUses();
                    }
                    DeadCode.Eliminate(ssa);
                    DumpWatchedProcedure("After strength reduction", ssa.Procedure);

                    // Definitions with multiple uses and variables joined by PHI functions become webs.
                    var web = new WebBuilder(program, ssa, program.InductionVariables, eventListener);
                    web.Transform();
                    ssa.ConvertBack(false);

                    DumpWatchedProcedure("After data flow analysis", ssa.Procedure);
                }
                catch (Exception ex)
                {
                    eventListener.Error(
                        eventListener.CreateProcedureNavigator(program, ssa.Procedure),
                        ex,
                        "An internal error occurred while building the expressions of {0}",
                        ssa.Procedure.Name);
                }
                eventListener.Advance(1);
            }
        }
Ejemplo n.º 2
0
        /// <summary>
        /// This callback is called from the SccFinder, which passes it a list
        /// of Procedures that form a SCC.
        /// </summary>
        /// <param name="procs"></param>
        private void UntangleProcedureScc(IList <Procedure> procs)
        {
            this.sccProcs = procs.ToHashSet();
            flow.CreateFlowsFor(procs);

            // Convert all procedures in the SCC to SSA form and perform
            // value propagation.
            var ssts = procs.Select(ConvertToSsa).ToArray();

            this.ssts.AddRange(ssts);
            DumpWatchedProcedure("After extra stack vars", ssts);

            // At this point, the computation of ProcedureFlow is possible.
            var trf = new TrashedRegisterFinder(program, flow, ssts, this.eventListener);

            trf.Compute();

            // New stack based variables may be available now.
            foreach (var sst in ssts)
            {
                var vp = new ValuePropagator(program.SegmentMap, sst.SsaState, program.CallGraph, dynamicLinker, this.eventListener);
                vp.Transform();
                sst.RenameFrameAccesses = true;
                sst.Transform();
                DumpWatchedProcedure("After extra stack vars", sst.SsaState.Procedure);
            }

            foreach (var ssa in ssts.Select(sst => sst.SsaState))
            {
                RemoveImplicitRegistersFromHellNodes(ssa);
                var sac = new SegmentedAccessClassifier(ssa);
                sac.Classify();
                var prj = new ProjectionPropagator(ssa, sac);
                prj.Transform();
                DumpWatchedProcedure("After projection propagation", ssa.Procedure);
            }

            var uid = new UsedRegisterFinder(flow, procs, this.eventListener);

            foreach (var sst in ssts)
            {
                var ssa = sst.SsaState;
                RemovePreservedUseInstructions(ssa);
                DeadCode.Eliminate(ssa);
                uid.ComputeLiveIn(ssa, true);
                var procFlow = flow[ssa.Procedure];
                RemoveDeadArgumentsFromCalls(ssa.Procedure, procFlow, ssts);
                DumpWatchedProcedure("After dead call argument removal", ssa.Procedure);
            }
            eventListener.Advance(procs.Count);
        }
Ejemplo n.º 3
0
        public void Transform()
        {
            CollectLiveOutStorages();
            DumpLiveOut();
            bool change;

            do
            {
                if (eventListener.IsCanceled())
                {
                    return;
                }
                change = false;
                this.wl.AddRange(ssaStates);
                while (wl.TryGetWorkItem(out SsaState ssa))
                {
                    if (this.eventListener.IsCanceled())
                    {
                        return;
                    }
                    var vp = new ValuePropagator(program.SegmentMap, ssa, program.CallGraph, dynamicLinker, eventListener);
                    vp.Transform();
                    change |= RemoveUnusedDefinedValues(ssa, wl);
                    //DataFlowAnalysis.DumpWatchedProcedure("After RemoveUnusedDefinedValues", ssa.Procedure);
                    change |= RemoveLiveInStorages(ssa.Procedure, dataFlow[ssa.Procedure], wl);
                    //DataFlowAnalysis.DumpWatchedProcedure("After RemoveLiveInStorages", ssa.Procedure);
                }
            } while (change);
            foreach (var proc in procToSsa.Keys)
            {
                var liveOut = CollectLiveOutStorages(proc);
                var flow    = this.dataFlow[proc];
                flow.BitsLiveOut = SummarizeStorageBitranges(flow.BitsLiveOut.Concat(liveOut));
                flow.grfLiveOut  = SummarizeFlagGroups(liveOut);
            }
        }
Ejemplo n.º 4
0
        /// <summary>
        /// Processes procedures individually, building complex expression trees out
        /// of the simple, close-to-the-machine code generated by the disassembly.
        /// </summary>
        /// <param name="rl"></param>
        public void BuildExpressionTrees()
        {
            int i = 0;

            foreach (Procedure proc in program.Procedures.Values)
            {
                eventListener.ShowProgress("Building complex expressions.", i, program.Procedures.Values.Count);
                ++i;

                try
                {
                    var larw = new LongAddRewriter(proc, program.Architecture);
                    larw.Transform();

                    Aliases alias = new Aliases(proc, program.Architecture, flow);
                    alias.Transform();

                    var doms = new DominatorGraph <Block>(proc.ControlGraph, proc.EntryBlock);
                    var sst  = new SsaTransform(flow, proc, importResolver, doms);
                    var ssa  = sst.SsaState;

                    var cce = new ConditionCodeEliminator(ssa.Identifiers, program.Platform);
                    cce.Transform();
                    //var cd = new ConstDivisionImplementedByMultiplication(ssa);
                    //cd.Transform();

                    DeadCode.Eliminate(proc, ssa);

                    var vp = new ValuePropagator(program.Architecture, ssa.Identifiers, proc);
                    vp.Transform();
                    DeadCode.Eliminate(proc, ssa);


                    // Build expressions. A definition with a single use can be subsumed
                    // into the using expression.

                    var coa = new Coalescer(proc, ssa);
                    coa.Transform();
                    DeadCode.Eliminate(proc, ssa);

                    var liv = new LinearInductionVariableFinder(
                        proc,
                        ssa.Identifiers,
                        new BlockDominatorGraph(proc.ControlGraph, proc.EntryBlock));
                    liv.Find();

                    foreach (KeyValuePair <LinearInductionVariable, LinearInductionVariableContext> de in liv.Contexts)
                    {
                        var str = new StrengthReduction(ssa, de.Key, de.Value);
                        str.ClassifyUses();
                        str.ModifyUses();
                    }
                    var opt = new OutParameterTransformer(proc, ssa.Identifiers);
                    opt.Transform();
                    DeadCode.Eliminate(proc, ssa);

                    // Definitions with multiple uses and variables joined by PHI functions become webs.
                    var web = new WebBuilder(proc, ssa.Identifiers, program.InductionVariables);
                    web.Transform();
                    ssa.ConvertBack(false);
                }
                catch (StatementCorrelatedException stex)
                {
                    eventListener.Error(
                        eventListener.CreateBlockNavigator(program, stex.Statement.Block),
                        stex,
                        "An error occurred during data flow analysis.");
                }
                catch (Exception ex)
                {
                    eventListener.Error(
                        new NullCodeLocation(proc.Name),
                        ex,
                        "An error occurred during data flow analysis.");
                }
            }
        }
Ejemplo n.º 5
0
        private void UntangleProcedureScc(IList <Procedure> procs)
        {
            if (procs.Count == 1)
            {
                var proc = procs[0];

                Aliases alias = new Aliases(proc, program.Architecture, flow);
                alias.Transform();

                // Transform the procedure to SSA state. When encountering 'call' instructions,
                // they can be to functions already visited. If so, they have a "ProcedureFlow"
                // associated with them. If they have not been visited, or are computed destinations
                // (e.g. vtables) they will have no "ProcedureFlow" associated with them yet, in
                // which case the the SSA treats the call as a "hell node".
                var doms = proc.CreateBlockDominatorGraph();
                var sst  = new SsaTransform(flow, proc, importResolver, doms);
                var ssa  = sst.SsaState;

                // Propagate condition codes and registers. At the end, the hope is that
                // all statements like (x86) mem[esp_42+4] will have been converted to
                // mem[fp - 30]. We also hope that procedure constants kept in registers
                // are propagated to the corresponding call sites.
                var cce = new ConditionCodeEliminator(ssa.Identifiers, program.Platform);
                cce.Transform();
                var vp = new ValuePropagator(program.Architecture, ssa.Identifiers, proc);
                vp.Transform();

                // Now compute SSA for the stack-based variables as well. That is:
                // mem[fp - 30] becomes wLoc30, while
                // mem[fp + 30] becomes wArg30.
                // This allows us to compute the dataflow of this procedure.
                sst.RenameFrameAccesses = true;
                sst.AddUseInstructions  = true;
                sst.Transform();

                // Propagate those newly discovered identifiers.
                vp.Transform();

                // At this point, the computation of _actual_ ProcedureFlow should be possible.
                var tid = new TrashedRegisterFinder2(program.Architecture, flow, proc, ssa.Identifiers, this.eventListener);
                tid.Compute();
                DeadCode.Eliminate(proc, ssa);

                // Build expressions. A definition with a single use can be subsumed
                // into the using expression.

                var coa = new Coalescer(proc, ssa);
                coa.Transform();
                DeadCode.Eliminate(proc, ssa);

                var liv = new LinearInductionVariableFinder(
                    proc,
                    ssa.Identifiers,
                    new BlockDominatorGraph(proc.ControlGraph, proc.EntryBlock));
                liv.Find();

                foreach (var de in liv.Contexts)
                {
                    var str = new StrengthReduction(ssa, de.Key, de.Value);
                    str.ClassifyUses();
                    str.ModifyUses();
                }

                //var opt = new OutParameterTransformer(proc, ssa.Identifiers);
                //opt.Transform();
                DeadCode.Eliminate(proc, ssa);

                // Definitions with multiple uses and variables joined by PHI functions become webs.
                var web = new WebBuilder(proc, ssa.Identifiers, program.InductionVariables);
                web.Transform();
                ssa.ConvertBack(false);
            }
            else
            {
                throw new NotImplementedException();
            }
        }
Ejemplo n.º 6
0
        /// <summary>
        /// Converts all registers and stack accesses to SSA variables.
        /// </summary>
        /// <param name="proc"></param>
        /// <returns>The SsaTransform for the procedure.</returns>
        public SsaTransform ConvertToSsa(Procedure proc)
        {
            if (program.NeedsSsaTransform)
            {
                // Transform the procedure to SSA state. When encountering 'call'
                // instructions, they can be to functions already visited. If so,
                // they have a "ProcedureFlow" associated with them. If they have
                // not been visited, or are computed destinations  (e.g. vtables)
                // they will have no "ProcedureFlow" associated with them yet, in
                // which case the the SSA treats the call as a "hell node".
                var sst = new SsaTransform(program, proc, sccProcs, dynamicLinker, this.ProgramDataFlow);
                var ssa = sst.Transform();
                DumpWatchedProcedure("After SSA", ssa.Procedure);

                // Merge unaligned memory accesses.
                var fuser = new UnalignedMemoryAccessFuser(ssa);
                fuser.Transform();

                // After value propagation expressions like (x86)
                // mem[esp_42+4] will have been converted to mem[fp - 30].
                // We also hope that procedure constants
                // kept in registers are propagated to the corresponding call
                // sites.
                var vp = new ValuePropagator(program.SegmentMap, ssa, program.CallGraph, dynamicLinker, eventListener);
                vp.Transform();
                DumpWatchedProcedure("After first VP", ssa.Procedure);

                // Fuse additions and subtractions that are linked by the carry flag.
                var larw = new LongAddRewriter(ssa);
                larw.Transform();

                // Propagate condition codes and registers.
                var cce = new ConditionCodeEliminator(ssa, program.Platform);
                cce.Transform();

                vp.Transform();
                DumpWatchedProcedure("After CCE", ssa.Procedure);

                // Now compute SSA for the stack-based variables as well. That is:
                // mem[fp - 30] becomes wLoc30, while
                // mem[fp + 30] becomes wArg30.
                // This allows us to compute the dataflow of this procedure.
                sst.RenameFrameAccesses = true;
                sst.Transform();
                DumpWatchedProcedure("After SSA frame accesses", ssa.Procedure);

                var icrw = new IndirectCallRewriter(program, ssa, eventListener);
                while (!eventListener.IsCanceled() && icrw.Rewrite())
                {
                    vp.Transform();
                    sst.RenameFrameAccesses = true;
                    sst.Transform();
                }

                var fpuGuesser = new FpuStackReturnGuesser(ssa);
                fpuGuesser.Rewrite();

                // By placing use statements in the exit block, we will collect
                // reaching definitions in the use statements.
                sst.AddUsesToExitBlock();
                sst.RemoveDeadSsaIdentifiers();

                // Backpropagate stack pointer from procedure return.
                var spBackpropagator = new StackPointerBackpropagator(ssa);
                spBackpropagator.BackpropagateStackPointer();
                DumpWatchedProcedure("After SP BP", ssa.Procedure);

                // Propagate those newly created stack-based identifiers.
                vp.Transform();
                DumpWatchedProcedure("After VP2", ssa.Procedure);

                return(sst);
            }
            else
            {
                // We are assuming phi functions are already generated.
                var sst = new SsaTransform(program, proc, sccProcs, dynamicLinker, this.ProgramDataFlow);
                return(sst);
            }
        }
Ejemplo n.º 7
0
        /// <summary>
        /// Processes procedures individually, building complex expression trees out
        /// of the simple, close-to-the-machine code generated by the disassembly.
        /// </summary>
        /// <param name="rl"></param>
        public void BuildExpressionTrees()
        {
            int i = 0;

            foreach (Procedure proc in program.Procedures.Values)
            {
                if (eventListener.IsCanceled())
                {
                    break;
                }
                eventListener.ShowProgress("Building complex expressions.", i, program.Procedures.Values.Count);
                ++i;

                try
                {
                    var sst = BuildSsaTransform(proc);
                    var ssa = sst.SsaState;

                    var fuser = new UnalignedMemoryAccessFuser(ssa);
                    fuser.Transform();

                    var vp = new ValuePropagator(program.SegmentMap, ssa, importResolver, eventListener);

                    sst.RenameFrameAccesses = true;
                    var icrw = new IndirectCallRewriter(program, ssa, eventListener);
                    while (!eventListener.IsCanceled() && icrw.Rewrite())
                    {
                        vp.Transform();
                        sst.Transform();
                    }
                    var cce = new ConditionCodeEliminator(ssa, program.Platform);
                    cce.Transform();
                    //var cd = new ConstDivisionImplementedByMultiplication(ssa);
                    //cd.Transform();

                    DeadCode.Eliminate(proc, ssa);

                    vp.Transform();
                    DeadCode.Eliminate(proc, ssa);

                    // Build expressions. A definition with a single use can be subsumed
                    // into the using expression.

                    var coa = new Coalescer(proc, ssa);
                    coa.Transform();
                    DeadCode.Eliminate(proc, ssa);

                    vp.Transform();

                    var liv = new LinearInductionVariableFinder(
                        proc,
                        ssa.Identifiers,
                        new BlockDominatorGraph(proc.ControlGraph, proc.EntryBlock));
                    liv.Find();

                    foreach (KeyValuePair <LinearInductionVariable, LinearInductionVariableContext> de in liv.Contexts)
                    {
                        var str = new StrengthReduction(ssa, de.Key, de.Value);
                        str.ClassifyUses();
                        str.ModifyUses();
                    }
                    var opt = new OutParameterTransformer(proc, ssa.Identifiers);
                    opt.Transform();
                    DeadCode.Eliminate(proc, ssa);

                    // Definitions with multiple uses and variables joined by PHI functions become webs.
                    var web = new WebBuilder(proc, ssa.Identifiers, program.InductionVariables);
                    web.Transform();
                    ssa.ConvertBack(false);
                }
                catch (StatementCorrelatedException stex)
                {
                    eventListener.Error(
                        eventListener.CreateStatementNavigator(program, stex.Statement),
                        stex,
                        "An error occurred during data flow analysis.");
                }
                catch (Exception ex)
                {
                    eventListener.Error(
                        new NullCodeLocation(proc.Name),
                        ex,
                        "An error occurred during data flow analysis.");
                }
            }
        }
Ejemplo n.º 8
0
        /// <summary>
        /// Processes procedures individually, building complex expression
        /// trees out of the simple, close-to-the-machine code generated by
        /// the disassembly.
        /// </summary>
        /// <param name="rl"></param>
        public void BuildExpressionTrees()
        {
            eventListener.ShowProgress("Building expressions.", 0, program.Procedures.Count);
            foreach (var sst in this.ssts !)
            {
                var ssa = sst.SsaState;
                try
                {
                    if (program.User.AggressiveBranchRemoval)
                    {
                        // This ends up being very aggressive and doesn't replicate the original
                        // binary code. See discussion on https://github.com/uxmal/reko/issues/932
                        DumpWatchedProcedure("urb", "Before unreachable block removal", ssa.Procedure);
                        var urb = new UnreachableBlockRemover(ssa, eventListener);
                        urb.Transform();
                    }

                    DumpWatchedProcedure("precoa", "Before expression coalescing", ssa.Procedure);

                    // Procedures should be untangled from each other. Now process
                    // each one separately.
                    DeadCode.Eliminate(ssa);

                    // Build expressions. A definition with a single use can be subsumed
                    // into the using expression.
                    var coa = new Coalescer(ssa);
                    coa.Transform();
                    DeadCode.Eliminate(ssa);

                    var vp = new ValuePropagator(program.SegmentMap, ssa, program.CallGraph, dynamicLinker, eventListener);
                    vp.Transform();

                    DumpWatchedProcedure("postcoa", "After expression coalescing", ssa.Procedure);

                    var liv = new LinearInductionVariableFinder(
                        ssa,
                        new BlockDominatorGraph(
                            ssa.Procedure.ControlGraph,
                            ssa.Procedure.EntryBlock));
                    liv.Find();

                    foreach (var de in liv.Contexts)
                    {
                        var str = new StrengthReduction(ssa, de.Key, de.Value);
                        str.ClassifyUses();
                        str.ModifyUses();
                    }
                    DeadCode.Eliminate(ssa);
                    DumpWatchedProcedure("sr", "After strength reduction", ssa.Procedure);

                    // Definitions with multiple uses and variables joined by PHI functions become webs.
                    var web = new WebBuilder(program, ssa, program.InductionVariables, eventListener);
                    web.Transform();
                    ssa.ConvertBack(false);

                    DumpWatchedProcedure("dfa", "After data flow analysis", ssa.Procedure);
                }
                catch (Exception ex)
                {
                    eventListener.Error(
                        eventListener.CreateProcedureNavigator(program, ssa.Procedure),
                        ex,
                        "An internal error occurred while building the expressions of {0}",
                        ssa.Procedure.Name);
                }
                eventListener.Advance(1);
            }
        }
Ejemplo n.º 9
0
        /// <summary>
        /// Converts all registers and stack accesses to SSA variables.
        /// </summary>
        /// <param name="proc"></param>
        /// <returns>The SsaTransform for the procedure.</returns>
        public SsaTransform ConvertToSsa(Procedure proc)
        {
            if (!program.NeedsSsaTransform)
            {
                // Some formats, like LLVM, already have phi functions.
                var sst = new SsaTransform(program, proc, sccProcs !, dynamicLinker, this.ProgramDataFlow);
                return(sst);
            }

            try
            {
                // Transform the procedure to SSA state. When encountering 'call'
                // instructions, they can be to functions already visited. If so,
                // they have a "ProcedureFlow" associated with them. If they have
                // not been visited, or are computed destinations  (e.g. vtables)
                // they will have no "ProcedureFlow" associated with them yet, in
                // which case the the SSA treats the call as a "hell node".
                var sst = new SsaTransform(program, proc, sccProcs !, dynamicLinker, this.ProgramDataFlow);
                var ssa = sst.Transform();
                DumpWatchedProcedure("ssa", "After SSA", ssa);
                // Merge unaligned memory accesses.
                var fuser = new UnalignedMemoryAccessFuser(ssa);
                fuser.Transform();

                // Fuse additions and subtractions that are linked by the carry flag.
                var larw = new LongAddRewriter(ssa, eventListener);
                larw.Transform();
                DumpWatchedProcedure("larw", "After long add rewriter", ssa);

                // After value propagation expressions like (x86)
                // mem[esp_42+4] will have been converted to mem[fp - 30].
                // We also hope that procedure constants
                // kept in registers are propagated to the corresponding call
                // sites.
                var vp = new ValuePropagator(program.SegmentMap, ssa, program.CallGraph, dynamicLinker, eventListener);
                vp.Transform();
                DumpWatchedProcedure("vp", "After first VP", ssa);

                // Value propagation may uncover more opportunities.
                larw = new LongAddRewriter(ssa, eventListener);
                larw.Transform();
                DumpWatchedProcedure("larw2", "After second long add rewriter", ssa);

                // Eliminate condition codes by discovering uses of ccodes
                // and replacing them with higher-level constructs.
                var cce = new ConditionCodeEliminator(program, ssa, eventListener);
                cce.Transform();
                vp.Transform();
                DumpWatchedProcedure("cce", "After CCE", ssa);

                // Now compute SSA for the stack-based variables as well. That is:
                // mem[fp - 30] becomes wLoc30, while
                // mem[fp + 30] becomes wArg30.
                // This allows us to compute the dataflow of this procedure.
                sst.RenameFrameAccesses = true;
                sst.Transform();
                DumpWatchedProcedure("ssaframe", "After SSA frame accesses", ssa);

                var icrw = new IndirectCallRewriter(program, ssa, eventListener);
                while (!eventListener.IsCanceled() && icrw.Rewrite())
                {
                    vp.Transform();
                    sst.RenameFrameAccesses = true;
                    sst.Transform();
                }

                var fpuGuesser = new FpuStackReturnGuesser(ssa, eventListener);
                fpuGuesser.Transform();
                DumpWatchedProcedure("fpug", "After FPU stack guesser", ssa);

                // By placing use statements in the exit block, we will collect
                // reaching definitions in the use statements.
                sst.AddUsesToExitBlock();
                sst.RemoveDeadSsaIdentifiers();

                // Backpropagate stack pointer from procedure return.
                var spBackpropagator = new StackPointerBackpropagator(ssa, eventListener);
                spBackpropagator.BackpropagateStackPointer();
                DumpWatchedProcedure("spbp", "After SP BP", ssa);

                // Propagate those newly created stack-based identifiers.
                vp.Transform();
                DumpWatchedProcedure("vp2", "After VP2", ssa);

                return(sst);
            }
            catch (Exception ex)
            {
                var nl     = Environment.NewLine;
                var banner = $"// {proc.Name} ==========={nl}{ex.Message}{nl}{ex.StackTrace}{nl}{nl}";
                services.GetService <ITestGenerationService>()?
                .ReportProcedure($"analysis_{99:00}_crash.txt", banner, proc);
                throw;
            }
        }