wazevo: adds support for context cancelation (#1709)

Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>

internal/engine/wazevo/backend/backend_test.go

@@ -3100,7 +3100,7 @@ L9 (SSA Block: blk6):
 		t.Run(tc.name, func(t *testing.T) {
 			ssab := ssa.NewBuilder()
 			offset := wazevoapi.NewModuleContextOffsetData(tc.m)
-			fc := frontend.NewFrontendCompiler(tc.m, ssab, &offset)
+			fc := frontend.NewFrontendCompiler(tc.m, ssab, &offset, false)
 			machine := newMachine()
 			machine.DisableStackCheck()
 			be := backend.NewCompiler(context.Background(), machine, ssab)

internal/engine/wazevo/backend/isa/arm64/machine_pro_epi_logue.go

@@ -376,7 +376,7 @@ func (m *machine) insertStackBoundsCheck(requiredStackSize int64, cur *instructi
 	ldrAddress.asULoad(operandNR(tmpRegVReg), addressMode{
 		kind: addressModeKindRegUnsignedImm12,
 		rn:   x0VReg, // execution context is always the first argument
-		imm:  wazevoapi.ExecutionContextOffsets.StackGrowCallSequenceAddress.I64(),
+		imm:  wazevoapi.ExecutionContextOffsets.StackGrowCallTrampolineAddress.I64(),
 	}, 64)
 	cur = linkInstr(cur, ldrAddress)
 

internal/engine/wazevo/call_engine.go

@@ -63,11 +63,12 @@ type (
 		stackGrowRequiredSize uintptr
 		// memoryGrowTrampolineAddress holds the address of memory grow trampoline function.
 		memoryGrowTrampolineAddress *byte
-		// stackGrowCallSequenceAddress holds the address of stack grow call sequence function.
-		stackGrowCallSequenceAddress *byte
+		// stackGrowCallTrampolineAddress holds the address of stack grow trampoline function.
+		stackGrowCallTrampolineAddress *byte
+		// checkModuleExitCodeTrampolineAddress holds the address of check-module-exit-code function.
+		checkModuleExitCodeTrampolineAddress *byte
 		// savedRegisters is the opaque spaces for save/restore registers.
 		// We want to align 16 bytes for each register, so we use [64][2]uint64.
-		_              uint64
 		savedRegisters [64][2]uint64
 		// goFunctionCallCalleeModuleContextOpaque is the pointer to the target Go function's moduleContextOpaque.
 		goFunctionCallCalleeModuleContextOpaque uintptr
@@ -138,6 +139,19 @@ func (c *callEngine) CallWithStack(ctx context.Context, paramResultStack []uint6
 
 // CallWithStack implements api.Function.
 func (c *callEngine) callWithStack(ctx context.Context, paramResultStack []uint64) (err error) {
+	p := c.parent
+	ensureTermination := p.parent.ensureTermination
+	m := p.module
+	if ensureTermination {
+		select {
+		case <-ctx.Done():
+			// If the provided context is already done, close the module and return the error.
+			m.CloseWithCtxErr(ctx)
+			return m.FailIfClosed()
+		default:
+		}
+	}
+
 	var paramResultPtr *uint64
 	if len(paramResultStack) > 0 {
 		paramResultPtr = &paramResultStack[0]
@@ -165,6 +179,11 @@ func (c *callEngine) callWithStack(ctx context.Context, paramResultStack []uint6
 		}
 	}()
 
+	if ensureTermination {
+		done := m.CloseModuleOnCanceledOrTimeout(ctx)
+		defer done()
+	}
+
 	entrypoint(c.preambleExecutable, c.executable, c.execCtxPtr, c.parent.opaquePtr, paramResultPtr, c.stackTop)
 	for {
 		switch ec := c.execCtx.exitCode; ec & wazevoapi.ExitCodeMask {
@@ -210,6 +229,15 @@ func (c *callEngine) callWithStack(ctx context.Context, paramResultStack []uint6
 			f.Call(ctx, mod, c.execCtx.goFunctionCallStack[:])
 			c.execCtx.exitCode = wazevoapi.ExitCodeOK
 			afterGoFunctionCallEntrypoint(c.execCtx.goCallReturnAddress, c.execCtxPtr, c.execCtx.stackPointerBeforeGoCall)
+		case wazevoapi.ExitCodeCheckModuleExitCode:
+			// Note: this operation must be done in Go, not native code. The reason is that
+			// native code cannot be preempted and that means it can block forever if there are not
+			// enough OS threads (which we don't have control over).
+			if err := m.FailIfClosed(); err != nil {
+				panic(err)
+			}
+			c.execCtx.exitCode = wazevoapi.ExitCodeOK
+			afterGoFunctionCallEntrypoint(c.execCtx.goCallReturnAddress, c.execCtxPtr, c.execCtx.stackPointerBeforeGoCall)
 		case wazevoapi.ExitCodeUnreachable:
 			panic(wasmruntime.ErrRuntimeUnreachable)
 		case wazevoapi.ExitCodeMemoryOutOfBounds:

internal/engine/wazevo/engine.go

@@ -45,6 +45,9 @@ type (
 	sharedFunctions struct {
 		// memoryGrowExecutable is a compiled executable for memory.grow builtin function.
 		memoryGrowExecutable []byte
+		// checkModuleExitCode is a compiled executable for checking module instance exit code. This
+		// is used when ensureTermination is true.
+		checkModuleExitCode []byte
 		// stackGrowExecutable is a compiled executable for growing stack builtin function.
 		stackGrowExecutable []byte
 		entryPreambles      map[*wasm.FunctionType][]byte
@@ -54,10 +57,11 @@ type (
 	compiledModule struct {
 		executable []byte
 		// functionOffsets maps a local function index to the offset in the executable.
-		functionOffsets []int
-		parent          *engine
-		module          *wasm.Module
-		entryPreambles  []*byte // indexed-correlated with the type index.
+		functionOffsets   []int
+		parent            *engine
+		module            *wasm.Module
+		entryPreambles    []*byte // indexed-correlated with the type index.
+		ensureTermination bool
 
 		// The followings are only available for non host modules.
 
@@ -78,7 +82,7 @@ func NewEngine(ctx context.Context, _ api.CoreFeatures, _ filecache.Cache) wasm.
 		machine:      machine,
 		be:           be,
 	}
-	e.compileBuiltinFunctions()
+	e.compileSharedFunctions()
 	return e
 }
 
@@ -108,6 +112,7 @@ func (e *engine) compileModule(ctx context.Context, module *wasm.Module, listene
 	e.rels = e.rels[:0]
 	cm := &compiledModule{
 		offsets: wazevoapi.NewModuleContextOffsetData(module), parent: e, module: module,
+		ensureTermination: ensureTermination,
 	}
 
 	if module.IsHostModule {
@@ -131,7 +136,7 @@ func (e *engine) compileModule(ctx context.Context, module *wasm.Module, listene
 
 	// Creates new compiler instances which are reused for each function.
 	ssaBuilder := ssa.NewBuilder()
-	fe := frontend.NewFrontendCompiler(module, ssaBuilder, &cm.offsets)
+	fe := frontend.NewFrontendCompiler(module, ssaBuilder, &cm.offsets, ensureTermination)
 	machine := newMachine()
 	be := backend.NewCompiler(ctx, machine, ssaBuilder)
 
@@ -154,7 +159,7 @@ func (e *engine) compileModule(ctx context.Context, module *wasm.Module, listene
 			ctx = wazevoapi.SetCurrentFunctionName(ctx, fmt.Sprintf("[%d/%d] \"%s\"", i, len(module.CodeSection)-1, name))
 		}
 
-		body, rels, err := e.compileLocalWasmFunction(ctx, module, wasm.Index(i), fe, ssaBuilder, be, listeners, ensureTermination)
+		body, rels, err := e.compileLocalWasmFunction(ctx, module, wasm.Index(i), fe, ssaBuilder, be, listeners)
 		if err != nil {
 			return nil, fmt.Errorf("compile function %d/%d: %v", i, len(module.CodeSection)-1, err)
 		}
@@ -214,7 +219,7 @@ func (e *engine) compileLocalWasmFunction(
 	fe *frontend.Compiler,
 	ssaBuilder ssa.Builder,
 	be backend.Compiler,
-	_ []experimental.FunctionListener, _ bool,
+	_ []experimental.FunctionListener,
 ) (body []byte, rels []backend.RelocationInfo, err error) {
 	typ := &module.TypeSection[module.FunctionSection[localFunctionIndex]]
 	codeSeg := &module.CodeSection[localFunctionIndex]
@@ -468,7 +473,7 @@ func (e *engine) NewModuleEngine(m *wasm.Module, mi *wasm.ModuleInstance) (wasm.
 	return me, nil
 }
 
-func (e *engine) compileBuiltinFunctions() {
+func (e *engine) compileSharedFunctions() {
 	e.sharedFunctions = &sharedFunctions{entryPreambles: make(map[*wasm.FunctionType][]byte)}
 
 	e.be.Init()
@@ -480,6 +485,15 @@ func (e *engine) compileBuiltinFunctions() {
 		e.sharedFunctions.memoryGrowExecutable = mmapExecutable(src)
 	}
 
+	e.be.Init()
+	{
+		src := e.machine.CompileGoFunctionTrampoline(wazevoapi.ExitCodeCheckModuleExitCode, &ssa.Signature{
+			Params:  []ssa.Type{ssa.TypeI32 /* exec context */},
+			Results: []ssa.Type{ssa.TypeI32},
+		}, false)
+		e.sharedFunctions.checkModuleExitCode = mmapExecutable(src)
+	}
+
 	// TODO: table grow, etc.
 
 	e.be.Init()
@@ -491,21 +505,26 @@ func (e *engine) compileBuiltinFunctions() {
 	e.setFinalizer(e.sharedFunctions, sharedFunctionsFinalizer)
 }
 
-func sharedFunctionsFinalizer(bf *sharedFunctions) {
-	if err := platform.MunmapCodeSegment(bf.memoryGrowExecutable); err != nil {
+func sharedFunctionsFinalizer(sf *sharedFunctions) {
+	if err := platform.MunmapCodeSegment(sf.memoryGrowExecutable); err != nil {
+		panic(err)
+	}
+	if err := platform.MunmapCodeSegment(sf.checkModuleExitCode); err != nil {
 		panic(err)
 	}
-	if err := platform.MunmapCodeSegment(bf.stackGrowExecutable); err != nil {
+	if err := platform.MunmapCodeSegment(sf.stackGrowExecutable); err != nil {
 		panic(err)
 	}
-	for _, f := range bf.entryPreambles {
+	for _, f := range sf.entryPreambles {
 		if err := platform.MunmapCodeSegment(f); err != nil {
 			panic(err)
 		}
 	}
 
-	bf.memoryGrowExecutable = nil
-	bf.stackGrowExecutable = nil
+	sf.memoryGrowExecutable = nil
+	sf.checkModuleExitCode = nil
+	sf.stackGrowExecutable = nil
+	sf.entryPreambles = nil
 }
 
 func compiledModuleFinalizer(cm *compiledModule) {

internal/engine/wazevo/engine_test.go

@@ -13,19 +13,37 @@ import (
 )
 
 func Test_sharedFunctionsFinalizer(t *testing.T) {
-	bf := &sharedFunctions{}
+	sf := &sharedFunctions{}
 
 	b1, err := platform.MmapCodeSegment(100)
 	require.NoError(t, err)
 
 	b2, err := platform.MmapCodeSegment(100)
 	require.NoError(t, err)
-	bf.memoryGrowExecutable = b1
-	bf.stackGrowExecutable = b2
 
-	sharedFunctionsFinalizer(bf)
-	require.Nil(t, bf.memoryGrowExecutable)
-	require.Nil(t, bf.stackGrowExecutable)
+	b3, err := platform.MmapCodeSegment(100)
+	require.NoError(t, err)
+
+	b4, err := platform.MmapCodeSegment(100)
+	require.NoError(t, err)
+	b5, err := platform.MmapCodeSegment(100)
+	require.NoError(t, err)
+
+	preabmles := map[*wasm.FunctionType][]byte{
+		{Params: []wasm.ValueType{}}:                  b4,
+		{Params: []wasm.ValueType{wasm.ValueTypeI32}}: b5,
+	}
+
+	sf.memoryGrowExecutable = b1
+	sf.stackGrowExecutable = b2
+	sf.checkModuleExitCode = b3
+	sf.entryPreambles = preabmles
+
+	sharedFunctionsFinalizer(sf)
+	require.Nil(t, sf.memoryGrowExecutable)
+	require.Nil(t, sf.stackGrowExecutable)
+	require.Nil(t, sf.checkModuleExitCode)
+	require.Nil(t, sf.entryPreambles)
 }
 
 func Test_compiledModuleFinalizer(t *testing.T) {

internal/engine/wazevo/frontend/frontend.go

@@ -17,9 +17,12 @@ type Compiler struct {
 	m      *wasm.Module
 	offset *wazevoapi.ModuleContextOffsetData
 	// ssaBuilder is a ssa.Builder used by this frontend.
-	ssaBuilder    ssa.Builder
-	signatures    map[*wasm.FunctionType]*ssa.Signature
-	memoryGrowSig ssa.Signature
+	ssaBuilder             ssa.Builder
+	signatures             map[*wasm.FunctionType]*ssa.Signature
+	memoryGrowSig          ssa.Signature
+	checkModuleExitCodeSig ssa.Signature
+	checkModuleExitCodeArg [1]ssa.Value
+	ensureTermination      bool
 
 	// Followings are reset by per function.
 
@@ -43,13 +46,14 @@ type Compiler struct {
 }
 
 // NewFrontendCompiler returns a frontend Compiler.
-func NewFrontendCompiler(m *wasm.Module, ssaBuilder ssa.Builder, offset *wazevoapi.ModuleContextOffsetData) *Compiler {
+func NewFrontendCompiler(m *wasm.Module, ssaBuilder ssa.Builder, offset *wazevoapi.ModuleContextOffsetData, ensureTermination bool) *Compiler {
 	c := &Compiler{
 		m:                   m,
 		ssaBuilder:          ssaBuilder,
 		br:                  bytes.NewReader(nil),
 		wasmLocalToVariable: make(map[wasm.Index]ssa.Variable),
 		offset:              offset,
+		ensureTermination:   ensureTermination,
 	}
 
 	c.signatures = make(map[*wasm.FunctionType]*ssa.Signature, len(m.TypeSection)+1)
@@ -70,6 +74,12 @@ func NewFrontendCompiler(m *wasm.Module, ssaBuilder ssa.Builder, offset *wazevoa
 	}
 	c.ssaBuilder.DeclareSignature(&c.memoryGrowSig)
 
+	c.checkModuleExitCodeSig = ssa.Signature{
+		ID: c.memoryGrowSig.ID + 1,
+		// Only takes execution context.
+		Params: []ssa.Type{ssa.TypeI64},
+	}
+	c.ssaBuilder.DeclareSignature(&c.checkModuleExitCodeSig)
 	return c
 }
 

internal/engine/wazevo/frontend/frontend_test.go

@@ -17,7 +17,8 @@ func TestCompiler_LowerToSSA(t *testing.T) {
 	// what output should look like, you can run:
 	// `~/wasmtime/target/debug/clif-util wasm --target aarch64-apple-darwin testcase.wat -p -t`
 	for _, tc := range []struct {
-		name string
+		name              string
+		ensureTermination bool
 		// m is the *wasm.Module to be compiled in this test.
 		m *wasm.Module
 		// targetIndex is the index of a local function to be compiled in this test.
@@ -219,6 +220,36 @@ blk0: (exec_ctx:i64, module_ctx:i64)
 
 blk1: () <-- (blk0,blk1)
 	Jump blk1
+`,
+		},
+		{
+			name: "loop - br / ensure termination", m: testcases.LoopBr.Module,
+			ensureTermination: true,
+			exp: `
+signatures:
+	sig2: i64_v
+
+blk0: (exec_ctx:i64, module_ctx:i64)
+	Jump blk1
+
+blk1: () <-- (blk0,blk1)
+	v2:i64 = Load exec_ctx, 0x58
+	CallIndirect v2:sig2, exec_ctx
+	Jump blk1
+
+blk2: ()
+`,
+			expAfterOpt: `
+signatures:
+	sig2: i64_v
+
+blk0: (exec_ctx:i64, module_ctx:i64)
+	Jump blk1
+
+blk1: () <-- (blk0,blk1)
+	v2:i64 = Load exec_ctx, 0x58
+	CallIndirect v2:sig2, exec_ctx
+	Jump blk1
 `,
 		},
 		{
@@ -1736,7 +1767,7 @@ blk4: () <-- (blk2,blk3)
 			b := ssa.NewBuilder()
 
 			offset := wazevoapi.NewModuleContextOffsetData(tc.m)
-			fc := NewFrontendCompiler(tc.m, b, &offset)
+			fc := NewFrontendCompiler(tc.m, b, &offset, tc.ensureTermination)
 			typeIndex := tc.m.FunctionSection[tc.targetIndex]
 			code := &tc.m.CodeSection[tc.targetIndex]
 			fc.Init(tc.targetIndex, &tc.m.TypeSection[typeIndex], code.LocalTypes, code.Body)

internal/engine/wazevo/frontend/lower.go

@@ -1012,6 +1012,19 @@ func (c *Compiler) lowerCurrentOpcode() {
 
 		c.switchTo(originalLen, loopHeader)
 
+		if c.ensureTermination {
+			checkModuleExitCodePtr := builder.AllocateInstruction().
+				AsLoad(c.execCtxPtrValue,
+					wazevoapi.ExecutionContextOffsets.CheckModuleExitCodeTrampolineAddress.U32(),
+					ssa.TypeI64,
+				).Insert(builder).Return()
+
+			c.checkModuleExitCodeArg[0] = c.execCtxPtrValue
+
+			builder.AllocateInstruction().
+				AsCallIndirect(checkModuleExitCodePtr, &c.checkModuleExitCodeSig, c.checkModuleExitCodeArg[:]).
+				Insert(builder)
+		}
 	case wasm.OpcodeIf:
 		bt := c.readBlockType()
 

internal/engine/wazevo/module_engine.go

@@ -142,7 +142,8 @@ func (m *moduleEngine) NewFunction(index wasm.Index) api.Function {
 	}
 
 	ce.execCtx.memoryGrowTrampolineAddress = &m.parent.sharedFunctions.memoryGrowExecutable[0]
-	ce.execCtx.stackGrowCallSequenceAddress = &m.parent.sharedFunctions.stackGrowExecutable[0]
+	ce.execCtx.stackGrowCallTrampolineAddress = &m.parent.sharedFunctions.stackGrowExecutable[0]
+	ce.execCtx.checkModuleExitCodeTrampolineAddress = &m.parent.sharedFunctions.checkModuleExitCode[0]
 	ce.init()
 	return ce
 }

internal/engine/wazevo/wazevo_test.go

@@ -58,7 +58,8 @@ func Test_ExecutionContextOffsets(t *testing.T) {
 	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.stackPointerBeforeGoCall)), offsets.StackPointerBeforeGoCall)
 	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.stackGrowRequiredSize)), offsets.StackGrowRequiredSize)
 	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.memoryGrowTrampolineAddress)), offsets.MemoryGrowTrampolineAddress)
-	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.stackGrowCallSequenceAddress)), offsets.StackGrowCallSequenceAddress)
+	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.stackGrowCallTrampolineAddress)), offsets.StackGrowCallTrampolineAddress)
+	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.checkModuleExitCodeTrampolineAddress)), offsets.CheckModuleExitCodeTrampolineAddress)
 	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.savedRegisters))%16, wazevoapi.Offset(0),
 		"SavedRegistersBegin must be aligned to 16 bytes")
 	require.Equal(t, wazevoapi.Offset(unsafe.Offsetof(execCtx.savedRegisters)), offsets.SavedRegistersBegin)