github.com/wasilibs/wazerox@v0.0.0-20240124024944-4923be63ab5f/internal/engine/compiler/engine_test.go

package compiler

import (
	"context"
	"errors"
	"fmt"
	"runtime"
	"testing"
	"unsafe"

	"github.com/wasilibs/wazerox/api"
	"github.com/wasilibs/wazerox/experimental"
	"github.com/wasilibs/wazerox/internal/bitpack"
	"github.com/wasilibs/wazerox/internal/platform"
	"github.com/wasilibs/wazerox/internal/testing/require"
	"github.com/wasilibs/wazerox/internal/wasm"
)

// testCtx is an arbitrary, non-default context. Non-nil also prevents linter errors.
var testCtx = context.WithValue(context.Background(), struct{}{}, "arbitrary")

// requireSupportedOSArch is duplicated also in the platform package to ensure no cyclic dependency.
func requireSupportedOSArch(t *testing.T) {
	if !platform.CompilerSupported() {
		t.Skip()
	}
}

type fakeFinalizer map[*compiledModule]func(module *compiledModule)

func (f fakeFinalizer) setFinalizer(obj interface{}, finalizer interface{}) {
	cf := obj.(*compiledModule)
	if _, ok := f[cf]; ok { // easier than adding a field for testing.T
		panic(fmt.Sprintf("BUG: %v already had its finalizer set", cf))
	}
	f[cf] = finalizer.(func(*compiledModule))
}

func TestCompiler_CompileModule(t *testing.T) {
	t.Run("ok", func(t *testing.T) {
		e := NewEngine(testCtx, api.CoreFeaturesV1, nil).(*engine)
		ff := fakeFinalizer{}
		e.setFinalizer = ff.setFinalizer

		okModule := &wasm.Module{
			TypeSection:     []wasm.FunctionType{{}},
			FunctionSection: []wasm.Index{0, 0, 0, 0},
			CodeSection: []wasm.Code{
				{Body: []byte{wasm.OpcodeEnd}},
				{Body: []byte{wasm.OpcodeEnd}},
				{Body: []byte{wasm.OpcodeEnd}},
				{Body: []byte{wasm.OpcodeEnd}},
			},
			ID: wasm.ModuleID{},
		}

		err := e.CompileModule(testCtx, okModule, nil, false)
		require.NoError(t, err)

		// Compiling same module shouldn't be compiled again, but instead should be cached.
		err = e.CompileModule(testCtx, okModule, nil, false)
		require.NoError(t, err)

		compiled, ok := e.codes[okModule.ID]
		require.True(t, ok)
		require.Equal(t, len(okModule.FunctionSection), len(compiled.functions))

		// Pretend the finalizer executed, by invoking them one-by-one.
		for k, v := range ff {
			v(k)
		}
	})

	t.Run("fail", func(t *testing.T) {
		errModule := &wasm.Module{
			TypeSection:     []wasm.FunctionType{{}},
			FunctionSection: []wasm.Index{0, 0, 0},
			CodeSection: []wasm.Code{
				{Body: []byte{wasm.OpcodeEnd}},
				{Body: []byte{wasm.OpcodeEnd}},
				{Body: []byte{wasm.OpcodeCall}}, // Call instruction without immediate for call target index is invalid and should fail to compile.
			},
			ID: wasm.ModuleID{},
		}

		e := NewEngine(testCtx, api.CoreFeaturesV1, nil).(*engine)
		err := e.CompileModule(testCtx, errModule, nil, false)
		require.EqualError(t, err, "failed to lower func[2]: handling instruction: apply stack failed for call: reading immediates: EOF")

		// On the compilation failure, the compiled functions must not be cached.
		_, ok := e.codes[errModule.ID]
		require.False(t, ok)
	})
}

func TestCompiler_Releasecode_Panic(t *testing.T) {
	captured := require.CapturePanic(func() {
		releaseCompiledModule(&compiledModule{
			compiledCode: &compiledCode{
				executable: makeCodeSegment(1, 2),
			},
		})
	})
	require.Contains(t, captured.Error(), "compiler: failed to munmap code segment")
}

// Ensures that value stack and call-frame stack are allocated on heap which
// allows us to safely access to their data region from native code.
// See comments on initialStackSize and initialCallFrameStackSize.
func TestCompiler_SliceAllocatedOnHeap(t *testing.T) {
	enabledFeatures := api.CoreFeaturesV1
	e := newEngine(enabledFeatures, nil)
	s := wasm.NewStore(enabledFeatures, e)

	const hostModuleName = "env"
	const hostFnName = "grow_and_shrink_goroutine_stack"
	hostFn := func() {
		// This function aggressively grow the goroutine stack by recursively
		// calling the function many times.
		callNum := 1000
		var growGoroutineStack func()
		growGoroutineStack = func() {
			if callNum != 0 {
				callNum--
				growGoroutineStack()
			}
		}
		growGoroutineStack()

		// Trigger relocation of goroutine stack because at this point we have the majority of
		// goroutine stack unused after recursive call.
		runtime.GC()
	}
	hm, err := wasm.NewHostModule(
		hostModuleName,
		[]string{hostFnName},
		map[string]*wasm.HostFunc{hostFnName: {ExportName: hostFnName, Code: wasm.Code{GoFunc: hostFn}}},
		enabledFeatures,
	)
	require.NoError(t, err)

	err = s.Engine.CompileModule(testCtx, hm, nil, false)
	require.NoError(t, err)

	typeIDs, err := s.GetFunctionTypeIDs(hm.TypeSection)
	require.NoError(t, err)

	_, err = s.Instantiate(testCtx, hm, hostModuleName, nil, typeIDs)
	require.NoError(t, err)

	const stackCorruption = "value_stack_corruption"
	const callStackCorruption = "call_stack_corruption"
	const expectedReturnValue = 0x1
	m := &wasm.Module{
		ImportFunctionCount: 1,
		TypeSection: []wasm.FunctionType{
			{Params: []wasm.ValueType{}, Results: []wasm.ValueType{wasm.ValueTypeI32}, ResultNumInUint64: 1},
			{Params: []wasm.ValueType{}, Results: []wasm.ValueType{}},
		},
		FunctionSection: []wasm.Index{
			wasm.Index(0),
			wasm.Index(0),
			wasm.Index(0),
		},
		CodeSection: []wasm.Code{
			{
				// value_stack_corruption
				Body: []byte{
					wasm.OpcodeCall, 0, // Call host function to shrink Goroutine stack
					// We expect this value is returned, but if the stack is allocated on
					// goroutine stack, we write this expected value into the old-location of
					// stack.
					wasm.OpcodeI32Const, expectedReturnValue,
					wasm.OpcodeEnd,
				},
			},
			{
				// call_stack_corruption
				Body: []byte{
					wasm.OpcodeCall, 3, // Call the wasm function below.
					// At this point, call stack's memory looks like [call_stack_corruption, index3]
					// With this function call it should end up [call_stack_corruption, host func]
					// but if the call-frame stack is allocated on goroutine stack, we exit the native code
					// with  [call_stack_corruption, index3] (old call frame stack) with HostCall status code,
					// and end up trying to call index3 as a host function which results in nil pointer exception.
					wasm.OpcodeCall, 0,
					wasm.OpcodeI32Const, expectedReturnValue,
					wasm.OpcodeEnd,
				},
			},
			{Body: []byte{wasm.OpcodeCall, 0, wasm.OpcodeEnd}},
		},
		ImportSection: []wasm.Import{{Module: hostModuleName, Name: hostFnName, DescFunc: 1}},
		ImportPerModule: map[string][]*wasm.Import{
			hostModuleName: {{Module: hostModuleName, Name: hostFnName, DescFunc: 1}},
		},
		ExportSection: []wasm.Export{
			{Type: wasm.ExternTypeFunc, Index: 1, Name: stackCorruption},
			{Type: wasm.ExternTypeFunc, Index: 2, Name: callStackCorruption},
		},
		Exports: map[string]*wasm.Export{
			stackCorruption:     {Type: wasm.ExternTypeFunc, Index: 1, Name: stackCorruption},
			callStackCorruption: {Type: wasm.ExternTypeFunc, Index: 2, Name: callStackCorruption},
		},
		ID: wasm.ModuleID{1},
	}

	err = s.Engine.CompileModule(testCtx, m, nil, false)
	require.NoError(t, err)

	typeIDs, err = s.GetFunctionTypeIDs(m.TypeSection)
	require.NoError(t, err)

	mi, err := s.Instantiate(testCtx, m, t.Name(), nil, typeIDs)
	require.NoError(t, err)

	for _, fnName := range []string{stackCorruption, callStackCorruption} {
		fnName := fnName
		t.Run(fnName, func(t *testing.T) {
			ret, err := mi.ExportedFunction(fnName).Call(testCtx)
			require.NoError(t, err)

			require.Equal(t, uint32(expectedReturnValue), uint32(ret[0]))
		})
	}
}

func TestCallEngine_builtinFunctionTableGrow(t *testing.T) {
	ce := &callEngine{
		stack: []uint64{
			0xff, // pseudo-ref
			1,    // num
			// Table Index = 0 (lower 32-bits), but the higher bits (32-63) are all sets,
			// which happens if the previous value on that stack location was 64-bit wide.
			0xffffffff << 32,
		},
		stackContext: stackContext{stackPointer: 3},
	}

	table := &wasm.TableInstance{References: []wasm.Reference{}, Min: 10}
	ce.builtinFunctionTableGrow([]*wasm.TableInstance{table})

	require.Equal(t, 1, len(table.References))
	require.Equal(t, uintptr(0xff), table.References[0])
}

func ptrAsUint64(f *function) uint64 {
	return uint64(uintptr(unsafe.Pointer(f)))
}

func TestCallEngine_deferredOnCall(t *testing.T) {
	s := &wasm.Module{
		FunctionSection: []wasm.Index{0, 1, 2},
		CodeSection:     []wasm.Code{{}, {}, {}},
		TypeSection:     []wasm.FunctionType{{}, {}, {}},
	}
	f1 := &function{
		funcType: &wasm.FunctionType{ParamNumInUint64: 2},
		parent:   &compiledFunction{parent: &compiledCode{source: s}, index: 0},
	}
	f2 := &function{
		funcType: &wasm.FunctionType{ParamNumInUint64: 2, ResultNumInUint64: 3},
		parent:   &compiledFunction{parent: &compiledCode{source: s}, index: 1},
	}
	f3 := &function{
		funcType: &wasm.FunctionType{ResultNumInUint64: 1},
		parent:   &compiledFunction{parent: &compiledCode{source: s}, index: 2},
	}

	ce := &callEngine{
		stack: []uint64{
			0xff, 0xff, // dummy argument for f1
			0, 0, 0, 0,
			0xcc, 0xcc, // local variable for f1.
			// <----- stack base point of f2 (top) == index 8.
			0xaa, 0xaa, 0xdeadbeaf, // dummy argument for f2 (0xaa, 0xaa) and the reserved slot for result 0xdeadbeaf)
			0, 0, ptrAsUint64(f1), 0, // callFrame
			0xcc, 0xcc, 0xcc, // local variable for f2.
			// <----- stack base point of f3 (top) == index 18
			0xdeadbeaf,                    // the reserved slot for result 0xdeadbeaf) from f3.
			0, 8 << 3, ptrAsUint64(f2), 0, // callFrame
		},
		stackContext: stackContext{
			stackBasePointerInBytes: 18 << 3, // currently executed function (f3)'s base pointer.
			stackPointer:            0xff,    // dummy supposed to be reset to zero.
		},
		moduleContext: moduleContext{
			fn:             f3, // currently executed function (f3)!
			moduleInstance: nil,
		},
	}

	beforeRecoverStack := ce.stack

	err := ce.deferredOnCall(context.Background(), &wasm.ModuleInstance{}, errors.New("some error"))
	require.EqualError(t, err, `some error (recovered by wazero)
wasm stack trace:
	.$2()
	.$1()
	.$0()`)

	// After recover, the state of callEngine must be reset except that the underlying slices must be intact
	// for the subsequent calls to avoid additional allocations on each call.
	require.Equal(t, uint64(0), ce.stackBasePointerInBytes)
	require.Equal(t, uint64(0), ce.stackPointer)
	require.Equal(t, nil, ce.moduleInstance)
	require.Equal(t, beforeRecoverStack, ce.stack)

	// Keep f1, f2, and f3 alive until we reach here, as we access these functions from the uint64 raw pointers in the stack.
	// In practice, they are guaranteed to be alive as they are held by moduleContext.
	runtime.KeepAlive(f1)
	runtime.KeepAlive(f2)
	runtime.KeepAlive(f3)
}

func TestCallEngine_initializeStack(t *testing.T) {
	const i32 = wasm.ValueTypeI32
	const stackSize = 10
	const initialVal = ^uint64(0)
	tests := []struct {
		name            string
		funcType        *wasm.FunctionType
		args            []uint64
		expStackPointer uint64
		expStack        [stackSize]uint64
	}{
		{
			name:            "no param/result",
			funcType:        &wasm.FunctionType{},
			expStackPointer: callFrameDataSizeInUint64,
			expStack: [stackSize]uint64{
				0, 0, 0, // zeroed call frame
				initialVal, initialVal, initialVal, initialVal, initialVal, initialVal, initialVal,
			},
		},
		{
			name: "no result",
			funcType: &wasm.FunctionType{
				Params:           []wasm.ValueType{i32, i32},
				ParamNumInUint64: 2,
			},
			args:            []uint64{0xdeadbeaf, 0xdeadbeaf},
			expStackPointer: callFrameDataSizeInUint64 + 2,
			expStack: [stackSize]uint64{
				0xdeadbeaf, 0xdeadbeaf, // arguments
				0, 0, 0, // zeroed call frame
				initialVal, initialVal, initialVal, initialVal, initialVal,
			},
		},
		{
			name: "no param",
			funcType: &wasm.FunctionType{
				Results:           []wasm.ValueType{i32, i32, i32},
				ResultNumInUint64: 3,
			},
			expStackPointer: callFrameDataSizeInUint64 + 3,
			expStack: [stackSize]uint64{
				initialVal, initialVal, initialVal, // reserved slots for results
				0, 0, 0, // zeroed call frame
				initialVal, initialVal, initialVal, initialVal,
			},
		},
		{
			name: "params > results",
			funcType: &wasm.FunctionType{
				Params:            []wasm.ValueType{i32, i32, i32, i32, i32},
				ParamNumInUint64:  5,
				Results:           []wasm.ValueType{i32, i32, i32},
				ResultNumInUint64: 3,
			},
			args:            []uint64{0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf},
			expStackPointer: callFrameDataSizeInUint64 + 5,
			expStack: [stackSize]uint64{
				0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf,
				0, 0, 0, // zeroed call frame
				initialVal, initialVal,
			},
		},
		{
			name: "params == results",
			funcType: &wasm.FunctionType{
				Params:            []wasm.ValueType{i32, i32, i32, i32, i32},
				ParamNumInUint64:  5,
				Results:           []wasm.ValueType{i32, i32, i32, i32, i32},
				ResultNumInUint64: 5,
			},
			args:            []uint64{0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf},
			expStackPointer: callFrameDataSizeInUint64 + 5,
			expStack: [stackSize]uint64{
				0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf,
				0, 0, 0, // zeroed call frame
				initialVal, initialVal,
			},
		},
		{
			name: "params < results",
			funcType: &wasm.FunctionType{
				Params:            []wasm.ValueType{i32, i32, i32},
				ParamNumInUint64:  3,
				Results:           []wasm.ValueType{i32, i32, i32, i32, i32},
				ResultNumInUint64: 5,
			},
			args:            []uint64{0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf},
			expStackPointer: callFrameDataSizeInUint64 + 5,
			expStack: [stackSize]uint64{
				0xdeafbeaf, 0xdeafbeaf, 0xdeafbeaf,
				initialVal, initialVal, // reserved for results
				0, 0, 0, // zeroed call frame
				initialVal, initialVal,
			},
		},
	}

	for _, tc := range tests {
		tc := tc
		t.Run(tc.name, func(t *testing.T) {
			initialStack := make([]uint64, stackSize)
			for i := range initialStack {
				initialStack[i] = initialVal
			}
			ce := &callEngine{stack: initialStack}
			ce.initializeStack(tc.funcType, tc.args)
			require.Equal(t, tc.expStackPointer, ce.stackPointer)
			require.Equal(t, tc.expStack[:], ce.stack)
		})
	}
}

func Test_callFrameOffset(t *testing.T) {
	require.Equal(t, 1, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 0, ResultNumInUint64: 1}))
	require.Equal(t, 10, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 5, ResultNumInUint64: 10}))
	require.Equal(t, 100, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 50, ResultNumInUint64: 100}))
	require.Equal(t, 1, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 1, ResultNumInUint64: 0}))
	require.Equal(t, 10, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 10, ResultNumInUint64: 5}))
	require.Equal(t, 100, callFrameOffset(&wasm.FunctionType{ParamNumInUint64: 100, ResultNumInUint64: 50}))
}

type stackEntry struct {
	def api.FunctionDefinition
}

func assertStackIterator(t *testing.T, it experimental.StackIterator, expected []stackEntry) {
	var actual []stackEntry
	for it.Next() {
		actual = append(actual, stackEntry{def: it.Function().Definition()})
	}
	require.Equal(t, expected, actual)
}

func TestCallEngine_builtinFunctionFunctionListenerBefore(t *testing.T) {
	currentContext := context.Background()

	f := &function{
		funcType: &wasm.FunctionType{ParamNumInUint64: 3},
		parent: &compiledFunction{
			listener: mockListener{
				before: func(ctx context.Context, _ api.Module, def api.FunctionDefinition, params []uint64, stackIterator experimental.StackIterator) {
					require.Equal(t, currentContext, ctx)
					require.Equal(t, []uint64{2, 3, 4}, params)
					assertStackIterator(t, stackIterator, []stackEntry{{def: def}})
				},
			},
			index: 0,
			parent: &compiledCode{source: &wasm.Module{
				FunctionSection: []wasm.Index{0},
				CodeSection:     []wasm.Code{{}},
				TypeSection:     []wasm.FunctionType{{}},
			}},
		},
	}
	ce := &callEngine{
		stack:        []uint64{0, 1, 2, 3, 4, 0, 0, 0},
		stackContext: stackContext{stackBasePointerInBytes: 16},
	}
	ce.builtinFunctionFunctionListenerBefore(currentContext, &wasm.ModuleInstance{}, f)
}

func TestCallEngine_builtinFunctionFunctionListenerAfter(t *testing.T) {
	currentContext := context.Background()
	f := &function{
		funcType: &wasm.FunctionType{ResultNumInUint64: 1},
		parent: &compiledFunction{
			listener: mockListener{
				after: func(ctx context.Context, mod api.Module, def api.FunctionDefinition, results []uint64) {
					require.Equal(t, currentContext, ctx)
					require.Equal(t, []uint64{5}, results)
				},
			},
			index: 0,
			parent: &compiledCode{source: &wasm.Module{
				FunctionSection: []wasm.Index{0},
				CodeSection:     []wasm.Code{{}},
				TypeSection:     []wasm.FunctionType{{}},
			}},
		},
	}

	ce := &callEngine{
		stack:        []uint64{0, 1, 2, 3, 4, 5},
		stackContext: stackContext{stackBasePointerInBytes: 40},
	}
	ce.builtinFunctionFunctionListenerAfter(currentContext, &wasm.ModuleInstance{}, f)
}

type mockListener struct {
	before func(context.Context, api.Module, api.FunctionDefinition, []uint64, experimental.StackIterator)
	after  func(context.Context, api.Module, api.FunctionDefinition, []uint64)
	abort  func(context.Context, api.Module, api.FunctionDefinition, error)
}

func (m mockListener) Before(ctx context.Context, mod api.Module, def api.FunctionDefinition, params []uint64, stackIterator experimental.StackIterator) {
	if m.before != nil {
		m.before(ctx, mod, def, params, stackIterator)
	}
}

func (m mockListener) After(ctx context.Context, mod api.Module, def api.FunctionDefinition, results []uint64) {
	if m.after != nil {
		m.after(ctx, mod, def, results)
	}
}

func (m mockListener) Abort(ctx context.Context, mod api.Module, def api.FunctionDefinition, err error) {
	if m.abort != nil {
		m.abort(ctx, mod, def, err)
	}
}

func TestFunction_getSourceOffsetInWasmBinary(t *testing.T) {
	tests := []struct {
		name               string
		pc, exp            uint64
		codeInitialAddress uintptr
		srcMap             sourceOffsetMap
	}{
		{name: "not found", srcMap: sourceOffsetMap{}},
		{
			name:               "first IR",
			pc:                 4000,
			codeInitialAddress: 3999,
			srcMap: sourceOffsetMap{
				irOperationOffsetsInNativeBinary: bitpack.NewOffsetArray([]uint64{
					0 /*4000-3999=1 exists here*/, 5, 8, 15,
				}),
				irOperationSourceOffsetsInWasmBinary: bitpack.NewOffsetArray([]uint64{
					10, 100, 800, 12344,
				}),
			},
			exp: 10,
		},
		{
			name:               "middle",
			pc:                 100,
			codeInitialAddress: 90,
			srcMap: sourceOffsetMap{
				irOperationOffsetsInNativeBinary: bitpack.NewOffsetArray([]uint64{
					0, 5, 8 /*100-90=10 exists here*/, 15,
				}),
				irOperationSourceOffsetsInWasmBinary: bitpack.NewOffsetArray([]uint64{
					10, 100, 800, 12344,
				}),
			},
			exp: 800,
		},
		{
			name:               "last",
			pc:                 9999,
			codeInitialAddress: 8999,
			srcMap: sourceOffsetMap{
				irOperationOffsetsInNativeBinary: bitpack.NewOffsetArray([]uint64{
					0, 5, 8, 15, /*9999-8999=1000 exists here*/
				}),
				irOperationSourceOffsetsInWasmBinary: bitpack.NewOffsetArray([]uint64{
					10, 100, 800, 12344,
				}),
			},
			exp: 12344,
		},
	}

	for _, tc := range tests {
		tc := tc
		t.Run(tc.name, func(t *testing.T) {
			f := function{
				parent:             &compiledFunction{sourceOffsetMap: tc.srcMap},
				codeInitialAddress: tc.codeInitialAddress,
			}

			actual := f.getSourceOffsetInWasmBinary(tc.pc)
			require.Equal(t, tc.exp, actual)
		})
	}
}