pkg/ifuzz: invert ifuzz and ifuzzimpl

ifuzzimpl imports the public interface package ifuzz
and prog package needs to import ifuzzimpl (implementation guts that
nobody outside of ifuzz should care about). This is not right.

Invert everything so that prog package only needs to import ifuzz
and ifuzz imports ifuzzimpl.

10 files changed, 321 insertions, 313 deletions

diff --git a/pkg/ifuzz/ifuzz.go b/pkg/ifuzz/ifuzz.go
index 4b51b30f3..45082834d 100644
--- a/pkg/ifuzz/ifuzz.go
+++ b/pkg/ifuzz/ifuzz.go
@@ -5,56 +5,134 @@ package ifuzz
 
 import (
 	"math/rand"
-)
 
-const (
-	ModeLong64 = iota
-	ModeProt32
-	ModeProt16
-	ModeReal16
-	ModeLast
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
+	_ "github.com/google/syzkaller/pkg/ifuzz/powerpc/generated" // pull in generated instruction descriptions
+	_ "github.com/google/syzkaller/pkg/ifuzz/x86/generated"     // pull in generated instruction descriptions
 )
 
-type Config struct {
-	Arch       string
-	Len        int         // number of instructions to generate
-	Mode       int         // one of ModeXXX
-	Priv       bool        // generate CPL=0 instructions (x86), HV/!PR mode (PPC)
-	Exec       bool        // generate instructions sequences interesting for execution
-	MemRegions []MemRegion // generated instructions will reference these regions
-}
-
-type MemRegion struct {
-	Start uint64
-	Size  uint64
-}
+type (
+	Config    = ifuzzimpl.Config
+	MemRegion = ifuzzimpl.MemRegion
+	Mode      = ifuzzimpl.Mode
+)
 
 const (
-	TypeExec = iota
-	TypePriv
-	TypeUser
-	TypeAll
-	TypeLast
+	ArchX86     = ifuzzimpl.ArchX86
+	ArchPowerPC = ifuzzimpl.ArchPowerPC
+	ModeLong64  = ifuzzimpl.ModeLong64
+	ModeProt32  = ifuzzimpl.ModeProt32
+	ModeProt16  = ifuzzimpl.ModeProt16
+	ModeReal16  = ifuzzimpl.ModeReal16
 )
 
-type Insn interface {
-	GetName() string
-	GetMode() int
-	GetPseudo() bool
-	GetPriv() bool
-	IsCompatible(cfg *Config) bool
-	Encode(cfg *Config, r *rand.Rand) []byte
+func Generate(cfg *Config, r *rand.Rand) []byte {
+	var text []byte
+	for i := 0; i < cfg.Len; i++ {
+		insn := randInsn(cfg, r)
+		text = append(text, insn.Encode(cfg, r)...)
+	}
+	return text
 }
 
-type InsnSet interface {
-	GetInsns(mode, insntype int) []Insn
-	Decode(mode int, text []byte) (int, error)
-	DecodeExt(mode int, text []byte) (int, error) // XED, to keep ifuzz_test happy
+func Mutate(cfg *Config, r *rand.Rand, text []byte) []byte {
+	insns := split(cfg, text)
+	retry := false
+	for stop := false; !stop || retry || len(insns) == 0; stop = r.Intn(2) == 0 {
+		retry = false
+		switch x := r.Intn(100); {
+		case x < 10 && len(insns) != 0:
+			// Delete instruction.
+			i := r.Intn(len(insns))
+			copy(insns[i:], insns[i+1:])
+			insns = insns[:len(insns)-1]
+		case x < 40 && len(insns) != 0:
+			// Replace instruction with another.
+			insn := randInsn(cfg, r)
+			text1 := insn.Encode(cfg, r)
+			i := r.Intn(len(insns))
+			insns[i] = text1
+		case x < 70 && len(insns) != 0:
+			// Mutate instruction.
+			i := r.Intn(len(insns))
+			text1 := insns[i]
+			for stop := false; !stop || len(text1) == 0; stop = r.Intn(2) == 0 {
+				switch x := r.Intn(100); {
+				case x < 5 && len(text1) != 0:
+					// Delete byte.
+					pos := r.Intn(len(text1))
+					copy(text1[pos:], text1[pos+1:])
+					text1 = text1[:len(text1)-1]
+				case x < 40 && len(text1) != 0:
+					// Replace a byte.
+					pos := r.Intn(len(text1))
+					text1[pos] = byte(r.Intn(256))
+				case x < 70 && len(text1) != 0:
+					// Flip a bit.
+					pos := r.Intn(len(text1))
+					text1[pos] ^= 1 << byte(r.Intn(8))
+				default:
+					// Insert a byte.
+					pos := r.Intn(len(text1) + 1)
+					text1 = append(text1, 0)
+					copy(text1[pos+1:], text1[pos:])
+					text1[pos] = byte(r.Intn(256))
+				}
+			}
+			insns[i] = text1
+		case len(insns) < cfg.Len:
+			// Insert a new instruction.
+			insn := randInsn(cfg, r)
+			text1 := insn.Encode(cfg, r)
+			i := r.Intn(len(insns) + 1)
+			insns = append(insns, nil)
+			copy(insns[i+1:], insns[i:])
+			insns[i] = text1
+		default:
+			retry = true
+		}
+	}
+	text = nil
+	for _, insn := range insns {
+		text = append(text, insn...)
+	}
+	return text
 }
 
-const (
-	ArchX86     = "x86"
-	ArchPowerPC = "powerpc"
-)
+func randInsn(cfg *Config, r *rand.Rand) ifuzzimpl.Insn {
+	insnset := ifuzzimpl.Arches[cfg.Arch]
+	var insns []ifuzzimpl.Insn
+	if cfg.Priv && cfg.Exec {
+		insns = insnset.GetInsns(cfg.Mode, ifuzzimpl.Type(r.Intn(3)))
+	} else if cfg.Priv {
+		insns = insnset.GetInsns(cfg.Mode, ifuzzimpl.Type(r.Intn(2)))
+	} else {
+		insns = insnset.GetInsns(cfg.Mode, ifuzzimpl.TypeUser)
+	}
+	return insns[r.Intn(len(insns))]
+}
 
-var SpecialNumbers = [...]uint64{0, 1 << 15, 1 << 16, 1 << 31, 1 << 32, 1 << 47, 1 << 47, 1 << 63}
+func split(cfg *Config, text []byte) [][]byte {
+	insnset := ifuzzimpl.Arches[cfg.Arch]
+	text = append([]byte{}, text...)
+	var insns [][]byte
+	var bad []byte
+	for len(text) != 0 {
+		n, err := insnset.Decode(cfg.Mode, text)
+		if err != nil || n == 0 {
+			bad = append(bad, text[0])
+			text = text[1:]
+			continue
+		}
+		if bad != nil {
+			insns = append(insns, bad)
+			bad = nil
+		}
+		insns = append(insns, text[:n])
+		text = text[n:]
+	}
+	if bad != nil {
+		insns = append(insns, bad)
+	}
+	return insns
+}
diff --git a/pkg/ifuzz/ifuzz_test.go b/pkg/ifuzz/ifuzz_test.go
index 5d02f8d1e..70177b5ef 100644
--- a/pkg/ifuzz/ifuzz_test.go
+++ b/pkg/ifuzz/ifuzz_test.go
@@ -1,7 +1,7 @@
 // Copyright 2017 syzkaller project authors. All rights reserved.
 // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
 
-package ifuzz_test
+package ifuzz
 
 import (
 	"encoding/hex"
@@ -10,13 +10,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/google/syzkaller/pkg/ifuzz"
 	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
-	_ "github.com/google/syzkaller/pkg/ifuzz/powerpc/generated"
-	_ "github.com/google/syzkaller/pkg/ifuzz/x86/generated"
 )
 
-var allArches = []string{ifuzz.ArchX86, ifuzz.ArchPowerPC}
+var allArches = []string{ArchX86, ArchPowerPC}
 
 func TestMode(t *testing.T) {
 	for _, arch := range allArches {
@@ -27,11 +24,11 @@ func TestMode(t *testing.T) {
 }
 
 func testMode(t *testing.T, arch string) {
-	all := make(map[ifuzz.Insn]bool)
-	for mode := 0; mode < ifuzz.ModeLast; mode++ {
+	all := make(map[ifuzzimpl.Insn]bool)
+	for mode := ifuzzimpl.Mode(0); mode < ifuzzimpl.ModeLast; mode++ {
 		for priv := 0; priv < 2; priv++ {
 			for exec := 0; exec < 2; exec++ {
-				cfg := &ifuzz.Config{
+				cfg := &Config{
 					Arch: arch,
 					Mode: mode,
 					Priv: priv != 0,
@@ -57,7 +54,7 @@ func TestDecode(t *testing.T) {
 }
 
 func testDecode(t *testing.T, arch string) {
-	insnset := ifuzzimpl.Types[arch]
+	insnset := ifuzzimpl.Arches[arch]
 	xedEnabled := false
 	if _, err := insnset.DecodeExt(0, nil); err == nil {
 		xedEnabled = true
@@ -70,8 +67,8 @@ func testDecode(t *testing.T, arch string) {
 	r := rand.New(rand.NewSource(seed))
 
 	for repeat := 0; repeat < 10; repeat++ {
-		for mode := 0; mode < ifuzz.ModeLast; mode++ {
-			cfg := &ifuzz.Config{
+		for mode := ifuzzimpl.Mode(0); mode < ifuzzimpl.ModeLast; mode++ {
+			cfg := &Config{
 				Arch: arch,
 				Mode: mode,
 				Priv: true,
diff --git a/pkg/ifuzz/ifuzzimpl/ifuzzimpl.go b/pkg/ifuzz/ifuzzimpl/ifuzzimpl.go
index f1ea64f37..71485172c 100644
--- a/pkg/ifuzz/ifuzzimpl/ifuzzimpl.go
+++ b/pkg/ifuzz/ifuzzimpl/ifuzzimpl.go
@@ -4,142 +4,80 @@
 package ifuzzimpl
 
 import (
-	"github.com/google/syzkaller/pkg/ifuzz"
 	"math/rand"
 )
 
-var (
-	Types = make(map[string]ifuzz.InsnSet)
+const (
+	ArchX86     = "x86"
+	ArchPowerPC = "powerpc"
 )
 
-func Register(arch string, insns ifuzz.InsnSet) {
-	Types[arch] = insns
-}
+var Arches = make(map[string]InsnSet)
 
-// ModeInsns returns list of all instructions for the given mode.
-func ModeInsns(cfg *ifuzz.Config) []ifuzz.Insn {
-	insnset := Types[cfg.Arch]
-	if cfg.Mode < 0 || cfg.Mode >= ifuzz.ModeLast {
-		panic("bad mode")
-	}
-	var insns []ifuzz.Insn
-	insns = append(insns, insnset.GetInsns(cfg.Mode, ifuzz.TypeUser)...)
-	if cfg.Priv {
-		insns = append(insns, insnset.GetInsns(cfg.Mode, ifuzz.TypePriv)...)
-		if cfg.Exec {
-			insns = append(insns, insnset.GetInsns(cfg.Mode, ifuzz.TypeExec)...)
-		}
-	}
-	return insns
+type (
+	Mode int
+	Type int
+)
+
+type Insn interface {
+	GetName() string
+	GetMode() int
+	GetPseudo() bool
+	GetPriv() bool
+	IsCompatible(cfg *Config) bool
+	Encode(cfg *Config, r *rand.Rand) []byte
 }
 
-func Generate(cfg *ifuzz.Config, r *rand.Rand) []byte {
-	var text []byte
-	for i := 0; i < cfg.Len; i++ {
-		insn := randInsn(cfg, r)
-		text = append(text, insn.Encode(cfg, r)...)
-	}
-	return text
+type InsnSet interface {
+	GetInsns(mode Mode, typ Type) []Insn
+	Decode(mode Mode, text []byte) (int, error)
+	DecodeExt(mode Mode, text []byte) (int, error) // XED, to keep ifuzz_test happy
 }
 
-func Mutate(cfg *ifuzz.Config, r *rand.Rand, text []byte) []byte {
-	insns := split(cfg, text)
-	retry := false
-	for stop := false; !stop || retry || len(insns) == 0; stop = r.Intn(2) == 0 {
-		retry = false
-		switch x := r.Intn(100); {
-		case x < 10 && len(insns) != 0:
-			// Delete instruction.
-			i := r.Intn(len(insns))
-			copy(insns[i:], insns[i+1:])
-			insns = insns[:len(insns)-1]
-		case x < 40 && len(insns) != 0:
-			// Replace instruction with another.
-			insn := randInsn(cfg, r)
-			text1 := insn.Encode(cfg, r)
-			i := r.Intn(len(insns))
-			insns[i] = text1
-		case x < 70 && len(insns) != 0:
-			// Mutate instruction.
-			i := r.Intn(len(insns))
-			text1 := insns[i]
-			for stop := false; !stop || len(text1) == 0; stop = r.Intn(2) == 0 {
-				switch x := r.Intn(100); {
-				case x < 5 && len(text1) != 0:
-					// Delete byte.
-					pos := r.Intn(len(text1))
-					copy(text1[pos:], text1[pos+1:])
-					text1 = text1[:len(text1)-1]
-				case x < 40 && len(text1) != 0:
-					// Replace a byte.
-					pos := r.Intn(len(text1))
-					text1[pos] = byte(r.Intn(256))
-				case x < 70 && len(text1) != 0:
-					// Flip a bit.
-					pos := r.Intn(len(text1))
-					text1[pos] ^= 1 << byte(r.Intn(8))
-				default:
-					// Insert a byte.
-					pos := r.Intn(len(text1) + 1)
-					text1 = append(text1, 0)
-					copy(text1[pos+1:], text1[pos:])
-					text1[pos] = byte(r.Intn(256))
-				}
-			}
-			insns[i] = text1
-		case len(insns) < cfg.Len:
-			// Insert a new instruction.
-			insn := randInsn(cfg, r)
-			text1 := insn.Encode(cfg, r)
-			i := r.Intn(len(insns) + 1)
-			insns = append(insns, nil)
-			copy(insns[i+1:], insns[i:])
-			insns[i] = text1
-		default:
-			retry = true
-		}
-	}
-	text = nil
-	for _, insn := range insns {
-		text = append(text, insn...)
-	}
-	return text
+type Config struct {
+	Arch       string
+	Len        int         // number of instructions to generate
+	Mode       Mode        // one of ModeXXX
+	Priv       bool        // generate CPL=0 instructions (x86), HV/!PR mode (PPC)
+	Exec       bool        // generate instructions sequences interesting for execution
+	MemRegions []MemRegion // generated instructions will reference these regions
 }
 
-func randInsn(cfg *ifuzz.Config, r *rand.Rand) ifuzz.Insn {
-	insnset := Types[cfg.Arch]
-	var insns []ifuzz.Insn
-	if cfg.Priv && cfg.Exec {
-		insns = insnset.GetInsns(cfg.Mode, r.Intn(3))
-	} else if cfg.Priv {
-		insns = insnset.GetInsns(cfg.Mode, r.Intn(2))
-	} else {
-		insns = insnset.GetInsns(cfg.Mode, ifuzz.TypeUser)
-	}
-	return insns[r.Intn(len(insns))]
+type MemRegion struct {
+	Start uint64
+	Size  uint64
 }
 
-func split(cfg *ifuzz.Config, text []byte) [][]byte {
-	insnset := Types[cfg.Arch]
-	text = append([]byte{}, text...)
-	var insns [][]byte
-	var bad []byte
-	for len(text) != 0 {
-		n, err := insnset.Decode(cfg.Mode, text)
-		if err != nil || n == 0 {
-			bad = append(bad, text[0])
-			text = text[1:]
-			continue
-		}
-		if bad != nil {
-			insns = append(insns, bad)
-			bad = nil
-		}
-		insns = append(insns, text[:n])
-		text = text[n:]
+const (
+	ModeLong64 Mode = iota
+	ModeProt32
+	ModeProt16
+	ModeReal16
+	ModeLast
+)
+
+const (
+	TypeExec Type = iota
+	TypePriv
+	TypeUser
+	TypeAll
+	TypeLast
+)
+
+// ModeInsns returns list of all instructions for the given mode.
+func ModeInsns(cfg *Config) []Insn {
+	insnset := Arches[cfg.Arch]
+	if cfg.Mode < 0 || cfg.Mode >= ModeLast {
+		panic("bad mode")
 	}
-	if bad != nil {
-		insns = append(insns, bad)
+	insns := insnset.GetInsns(cfg.Mode, TypeUser)
+	if cfg.Priv {
+		insns = append(insns, insnset.GetInsns(cfg.Mode, TypePriv)...)
+		if cfg.Exec {
+			insns = append(insns, insnset.GetInsns(cfg.Mode, TypeExec)...)
+		}
 	}
 	return insns
 }
+
+var SpecialNumbers = [...]uint64{0, 1 << 15, 1 << 16, 1 << 31, 1 << 32, 1 << 47, 1 << 47, 1 << 63}
diff --git a/pkg/ifuzz/powerpc/powerpc.go b/pkg/ifuzz/powerpc/powerpc.go
index 0dd3a57d6..5559c491c 100644
--- a/pkg/ifuzz/powerpc/powerpc.go
+++ b/pkg/ifuzz/powerpc/powerpc.go
@@ -16,9 +16,9 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
-	"github.com/google/syzkaller/pkg/ifuzz"
-	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 	"math/rand"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 type InsnBits struct {
@@ -35,20 +35,20 @@ type Insn struct {
 	Opcode uint32
 	Mask   uint32
 
-	generator func(cfg *ifuzz.Config, r *rand.Rand) []byte
+	generator func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte
 }
 
 type InsnSetPowerPC struct {
 	Insns     []*Insn
-	modeInsns [ifuzz.ModeLast][ifuzz.TypeLast][]ifuzz.Insn
+	modeInsns [ifuzzimpl.ModeLast][ifuzzimpl.TypeLast][]ifuzzimpl.Insn
 	insnMap   map[string]*Insn
 }
 
-func (insnset *InsnSetPowerPC) GetInsns(mode, insntype int) []ifuzz.Insn {
-	return insnset.modeInsns[mode][insntype]
+func (insnset *InsnSetPowerPC) GetInsns(mode ifuzzimpl.Mode, typ ifuzzimpl.Type) []ifuzzimpl.Insn {
+	return insnset.modeInsns[mode][typ]
 }
 
-func (insnset *InsnSetPowerPC) Decode(mode int, text []byte) (int, error) {
+func (insnset *InsnSetPowerPC) Decode(mode ifuzzimpl.Mode, text []byte) (int, error) {
 	if len(text) < 4 {
 		return 0, errors.New("must be at least 4 bytes")
 	}
@@ -61,7 +61,7 @@ func (insnset *InsnSetPowerPC) Decode(mode int, text []byte) (int, error) {
 	return 0, fmt.Errorf("unrecognised instruction %08x", insn32)
 }
 
-func (insnset *InsnSetPowerPC) DecodeExt(mode int, text []byte) (int, error) {
+func (insnset *InsnSetPowerPC) DecodeExt(mode ifuzzimpl.Mode, text []byte) (int, error) {
 	return 0, fmt.Errorf("no external decoder")
 }
 
@@ -85,7 +85,7 @@ func (insn *Insn) EncodeParam(v map[string]uint, r *rand.Rand) []byte {
 	return ret
 }
 
-func (insn Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
+func (insn Insn) Encode(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 	if insn.Pseudo {
 		return insn.generator(cfg, r)
 	}
@@ -94,39 +94,39 @@ func (insn Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 }
 
 func Register(insns []*Insn) {
-	var insnset InsnSetPowerPC
-
-	insnset.Insns = insns
-	if len(insnset.Insns) == 0 {
+	if len(insns) == 0 {
 		panic("no instructions")
 	}
-	insnset.insnMap = make(map[string]*Insn)
+	insnset := &InsnSetPowerPC{
+		Insns:   insns,
+		insnMap: make(map[string]*Insn),
+	}
 	for _, insn := range insnset.Insns {
 		insnset.insnMap[insn.GetName()] = insn
 	}
 	insnset.initPseudo()
-	for mode := 0; mode < ifuzz.ModeLast; mode++ {
+	for mode := ifuzzimpl.Mode(0); mode < ifuzzimpl.ModeLast; mode++ {
 		for _, insn := range insnset.Insns {
 			if insn.GetMode()&(1<<uint(mode)) == 0 {
 				continue
 			}
 			if insn.GetPseudo() {
-				insnset.modeInsns[mode][ifuzz.TypeExec] =
-					append(insnset.modeInsns[mode][ifuzz.TypeExec], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypeExec] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeExec], insn)
 			} else if insn.GetPriv() {
-				insnset.modeInsns[mode][ifuzz.TypePriv] =
-					append(insnset.modeInsns[mode][ifuzz.TypePriv], ifuzz.Insn(insn))
-				insnset.modeInsns[mode][ifuzz.TypeAll] =
-					append(insnset.modeInsns[mode][ifuzz.TypeAll], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypePriv] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypePriv], insn)
+				insnset.modeInsns[mode][ifuzzimpl.TypeAll] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeAll], insn)
 			} else {
-				insnset.modeInsns[mode][ifuzz.TypeUser] =
-					append(insnset.modeInsns[mode][ifuzz.TypeUser], ifuzz.Insn(insn))
-				insnset.modeInsns[mode][ifuzz.TypeAll] =
-					append(insnset.modeInsns[mode][ifuzz.TypeAll], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypeUser] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeUser], insn)
+				insnset.modeInsns[mode][ifuzzimpl.TypeAll] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeAll], insn)
 			}
 		}
 	}
-	ifuzzimpl.Register(ifuzz.ArchPowerPC, ifuzz.InsnSet(&insnset))
+	ifuzzimpl.Arches[ifuzzimpl.ArchPowerPC] = insnset
 }
 
 func (insn Insn) GetName() string {
@@ -135,9 +135,9 @@ func (insn Insn) GetName() string {
 
 func (insn Insn) GetMode() int {
 	if insn.M64 {
-		return (1 << ifuzz.ModeLong64)
+		return (1 << ifuzzimpl.ModeLong64)
 	}
-	return (1 << ifuzz.ModeLong64) | (1 << ifuzz.ModeProt32)
+	return (1 << ifuzzimpl.ModeLong64) | (1 << ifuzzimpl.ModeProt32)
 }
 
 func (insn Insn) GetPriv() bool {
@@ -148,8 +148,8 @@ func (insn Insn) GetPseudo() bool {
 	return insn.Pseudo
 }
 
-func (insn Insn) IsCompatible(cfg *ifuzz.Config) bool {
-	if cfg.Mode < 0 || cfg.Mode >= ifuzz.ModeLast {
+func (insn Insn) IsCompatible(cfg *ifuzzimpl.Config) bool {
+	if cfg.Mode < 0 || cfg.Mode >= ifuzzimpl.ModeLast {
 		panic("bad mode")
 	}
 	if insn.Priv && !cfg.Priv {
@@ -158,7 +158,7 @@ func (insn Insn) IsCompatible(cfg *ifuzz.Config) bool {
 	if insn.Pseudo && !cfg.Exec {
 		return false
 	}
-	if insn.M64 && ((1 << uint(cfg.Mode)) != ifuzz.ModeLong64) {
+	if insn.M64 && ((1 << uint(cfg.Mode)) != ifuzzimpl.ModeLong64) {
 		return false
 	}
 	return true
diff --git a/pkg/ifuzz/powerpc/pseudo.go b/pkg/ifuzz/powerpc/pseudo.go
index e39863b32..d9d1a0039 100644
--- a/pkg/ifuzz/powerpc/pseudo.go
+++ b/pkg/ifuzz/powerpc/pseudo.go
@@ -4,8 +4,9 @@
 package powerpc
 
 import (
-	"github.com/google/syzkaller/pkg/ifuzz"
 	"math/rand"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 // nolint:dupl
@@ -14,7 +15,7 @@ func (insnset *InsnSetPowerPC) initPseudo() {
 		Name:   "PSEUDO_hypercall",
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(insnset, cfg, r)
 			gen.sc(1)
 			return gen.text
@@ -24,7 +25,7 @@ func (insnset *InsnSetPowerPC) initPseudo() {
 		Name:   "PSEUDO_syscall",
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(insnset, cfg, r)
 			gen.sc(0)
 			return gen.text
@@ -34,7 +35,7 @@ func (insnset *InsnSetPowerPC) initPseudo() {
 		Name:   "PSEUDO_ultracall",
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(insnset, cfg, r)
 			gen.sc(2)
 			return gen.text
@@ -44,12 +45,12 @@ func (insnset *InsnSetPowerPC) initPseudo() {
 
 type generator struct {
 	imap map[string]*Insn
-	mode int
+	mode ifuzzimpl.Mode
 	r    *rand.Rand
 	text []byte
 }
 
-func makeGen(insnset *InsnSetPowerPC, cfg *ifuzz.Config, r *rand.Rand) *generator {
+func makeGen(insnset *InsnSetPowerPC, cfg *ifuzzimpl.Config, r *rand.Rand) *generator {
 	return &generator{
 		imap: insnset.insnMap,
 		mode: cfg.Mode,
diff --git a/pkg/ifuzz/x86/decode.go b/pkg/ifuzz/x86/decode.go
index ca611ac69..e02a3a63f 100644
--- a/pkg/ifuzz/x86/decode.go
+++ b/pkg/ifuzz/x86/decode.go
@@ -5,26 +5,27 @@ package x86
 
 import (
 	"fmt"
-	"github.com/google/syzkaller/pkg/ifuzz"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 // Decode decodes instruction length for the given mode.
 // It can have falsely decode incorrect instructions,
 // but should not fail to decode correct instructions.
 // nolint: gocyclo, nestif, gocognit, funlen
-func (insnset *InsnSetX86) Decode(mode int, text []byte) (int, error) {
+func (insnset *InsnSetX86) Decode(mode ifuzzimpl.Mode, text []byte) (int, error) {
 	if len(text) == 0 {
 		return 0, fmt.Errorf("zero-length instruction")
 	}
 	prefixes := prefixes32
 	var operSize, immSize, dispSize, addrSize int
 	switch mode {
-	case ifuzz.ModeLong64:
+	case ifuzzimpl.ModeLong64:
 		operSize, immSize, dispSize, addrSize = 4, 4, 4, 8
 		prefixes = prefixes64
-	case ifuzz.ModeProt32:
+	case ifuzzimpl.ModeProt32:
 		operSize, immSize, dispSize, addrSize = 4, 4, 4, 4
-	case ifuzz.ModeProt16, ifuzz.ModeReal16:
+	case ifuzzimpl.ModeProt16, ifuzzimpl.ModeReal16:
 		operSize, immSize, dispSize, addrSize = 2, 2, 2, 2
 	default:
 		panic("bad mode")
@@ -35,7 +36,7 @@ func (insnset *InsnSetX86) Decode(mode int, text []byte) (int, error) {
 	if len(text) > 1 {
 		// There are only 2 32-bit instructions that look like VEX-prefixed but are actually not: LDS, LES.
 		// They always reference memory (mod!=3), but all VEX instructions have "mod=3" where LDS/LES would have mod.
-		if (text[0] == 0xc4 || text[0] == 0xc5) && (mode == ifuzz.ModeLong64 || text[1]&0xc0 == 0xc0) {
+		if (text[0] == 0xc4 || text[0] == 0xc5) && (mode == ifuzzimpl.ModeLong64 || text[1]&0xc0 == 0xc0) {
 			vex = true
 		}
 		// There is only one instruction that looks like XOP-prefixed but is actually not: POP.
@@ -207,7 +208,7 @@ nextInsn:
 	return 0, fmt.Errorf("unknown instruction")
 }
 
-var XedDecode func(mode int, text []byte) (int, error)
+var XedDecode func(mode ifuzzimpl.Mode, text []byte) (int, error)
 
 var (
 	prefixes32 = map[byte]bool{
@@ -225,7 +226,7 @@ var (
 	}
 )
 
-func (insnset *InsnSetX86) DecodeExt(mode int, text []byte) (int, error) {
+func (insnset *InsnSetX86) DecodeExt(mode ifuzzimpl.Mode, text []byte) (int, error) {
 	if XedDecode != nil && text != nil && len(text) > 0 {
 		return XedDecode(mode, text)
 	}
diff --git a/pkg/ifuzz/x86/encode.go b/pkg/ifuzz/x86/encode.go
index b73a22c14..9258bc41c 100644
--- a/pkg/ifuzz/x86/encode.go
+++ b/pkg/ifuzz/x86/encode.go
@@ -8,12 +8,13 @@
 package x86
 
 import (
-	"github.com/google/syzkaller/pkg/ifuzz"
 	"math/rand"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 // nolint: gocyclo, nestif, gocognit, funlen
-func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
+func (insn *Insn) Encode(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 	if !insn.IsCompatible(cfg) {
 		panic("instruction is not suitable for this mode")
 	}
@@ -23,11 +24,11 @@ func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 
 	var operSize, immSize, dispSize, addrSize int
 	switch cfg.Mode {
-	case ifuzz.ModeLong64:
+	case ifuzzimpl.ModeLong64:
 		operSize, immSize, dispSize, addrSize = 4, 4, 4, 8
-	case ifuzz.ModeProt32:
+	case ifuzzimpl.ModeProt32:
 		operSize, immSize, dispSize, addrSize = 4, 4, 4, 4
-	case ifuzz.ModeProt16, ifuzz.ModeReal16:
+	case ifuzzimpl.ModeProt16, ifuzzimpl.ModeReal16:
 		operSize, immSize, dispSize, addrSize = 2, 2, 2, 2
 	default:
 		panic("bad mode")
@@ -53,7 +54,7 @@ func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 			if !insn.No66Prefix {
 				prefixes = append(prefixes, 0x66) // operand size
 			}
-			if cfg.Mode == ifuzz.ModeLong64 || !insn.Mem32 {
+			if cfg.Mode == ifuzzimpl.ModeLong64 || !insn.Mem32 {
 				prefixes = append(prefixes, 0x67) // address size
 			}
 			if !insn.NoRepPrefix {
@@ -70,7 +71,7 @@ func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 
 		// REX
 		var rex byte
-		if cfg.Mode == ifuzz.ModeLong64 && r.Intn(2) == 0 {
+		if cfg.Mode == ifuzzimpl.ModeLong64 && r.Intn(2) == 0 {
 			// bit 0 - B
 			// bit 1 - X
 			// bit 2 - R
@@ -118,7 +119,7 @@ func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 		code = append(code, insn.Vex)
 		vexR = byte(1)
 		vexX = byte(1)
-		if cfg.Mode == ifuzz.ModeLong64 {
+		if cfg.Mode == ifuzzimpl.ModeLong64 {
 			vexR = byte(r.Intn(2))
 			vexX = byte(r.Intn(2))
 		}
@@ -146,7 +147,7 @@ func (insn *Insn) Encode(cfg *ifuzz.Config, r *rand.Rand) []byte {
 		code = append(code, vexR<<7|vexX<<6|vexB<<5|insn.VexMap)
 		code = append(code, W<<7|vvvv<<3|L<<2|pp)
 		// TODO: short encoding
-		if cfg.Mode != ifuzz.ModeLong64 {
+		if cfg.Mode != ifuzzimpl.ModeLong64 {
 			vvvv |= 8
 		}
 	}
diff --git a/pkg/ifuzz/x86/gen/gen.go b/pkg/ifuzz/x86/gen/gen.go
index d1a490625..3622ba248 100644
--- a/pkg/ifuzz/x86/gen/gen.go
+++ b/pkg/ifuzz/x86/gen/gen.go
@@ -13,7 +13,7 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/google/syzkaller/pkg/ifuzz"
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 	"github.com/google/syzkaller/pkg/ifuzz/x86"
 	"github.com/google/syzkaller/pkg/serializer"
 )
@@ -102,7 +102,7 @@ func main() {
 			insn.Extension = vals[0]
 			switch insn.Extension {
 			case "FMA", "AVX2", "AVX", "F16C", "BMI2", "BMI", "XOP", "FMA4", "AVXAES", "BMI1", "AVX2GATHER":
-				insn.Mode = 1<<ifuzz.ModeLong64 | 1<<ifuzz.ModeProt32
+				insn.Mode = 1<<ifuzzimpl.ModeLong64 | 1<<ifuzzimpl.ModeProt32
 			}
 			insn.Avx2Gather = insn.Extension == "AVX2GATHER"
 		case "PATTERN":
@@ -201,7 +201,7 @@ func parsePattern(insn *x86.Insn, vals []string) error {
 		return errSkip("")
 	}
 	if insn.Mode == 0 {
-		insn.Mode = 1<<ifuzz.ModeLast - 1
+		insn.Mode = 1<<ifuzzimpl.ModeLast - 1
 	}
 	insn.Mod = -100
 	insn.Reg = -100
@@ -314,7 +314,7 @@ func parsePattern(insn *x86.Insn, vals []string) error {
 		// VOP/VEX
 		case v == "XOPV":
 			insn.Vex = 0x8f
-			insn.Mode &^= 1 << ifuzz.ModeReal16
+			insn.Mode &^= 1 << ifuzzimpl.ModeReal16
 		case v == "EVV":
 			insn.Vex = 0xc4
 		case v == "VV1":
@@ -355,13 +355,13 @@ func parsePattern(insn *x86.Insn, vals []string) error {
 
 		// Modes.
 		case v == "mode64":
-			insn.Mode &= 1 << ifuzz.ModeLong64
+			insn.Mode &= 1 << ifuzzimpl.ModeLong64
 		case v == "not64":
-			insn.Mode &^= 1 << ifuzz.ModeLong64
+			insn.Mode &^= 1 << ifuzzimpl.ModeLong64
 		case v == "mode32":
-			insn.Mode &= 1 << ifuzz.ModeProt32
+			insn.Mode &= 1 << ifuzzimpl.ModeProt32
 		case v == "mode16":
-			insn.Mode &= 1<<ifuzz.ModeProt16 | 1<<ifuzz.ModeReal16
+			insn.Mode &= 1<<ifuzzimpl.ModeProt16 | 1<<ifuzzimpl.ModeReal16
 		case v == "eamode64",
 			v == "eamode32",
 			v == "eamode16",
diff --git a/pkg/ifuzz/x86/pseudo.go b/pkg/ifuzz/x86/pseudo.go
index 1efbcfbcc..412b5813f 100644
--- a/pkg/ifuzz/x86/pseudo.go
+++ b/pkg/ifuzz/x86/pseudo.go
@@ -4,18 +4,19 @@
 package x86
 
 import (
-	"github.com/google/syzkaller/pkg/ifuzz"
 	"math/rand"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 // nolint: funlen
 func (insnset *InsnSetX86) initPseudo() {
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_RDMSR",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			msr := msrs[r.Intn(len(msrs))]
 			gen.mov32(regECX, msr)
@@ -25,10 +26,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_WRMSR",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			msr := msrs[r.Intn(len(msrs))]
 			v := generateInt(cfg, r, 8)
@@ -41,10 +42,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_PCI_READ",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			addr, port, size := pciAddrPort(r)
 			gen.out32(0xcf8, addr)
@@ -54,10 +55,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_PCI_WRITE",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			addr, port, size := pciAddrPort(r)
 			val := generateInt(cfg, r, 4)
@@ -68,10 +69,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_PORT_READ",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			port := ports[r.Intn(len(ports))]
 			gen.in(port, r.Intn(3))
@@ -80,10 +81,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_PORT_WRITE",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			port := ports[r.Intn(len(ports))]
 			val := generateInt(cfg, r, 4)
@@ -93,10 +94,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_XOR_CR",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			cr := controlRegisters[r.Intn(len(controlRegisters))]
 			var v uint32
@@ -114,10 +115,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_XOR_EFER",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			gen.mov32(regECX, eferMSR)
 			gen.byte(0x0f, 0x32) // rdmsr
@@ -129,16 +130,16 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_SET_BREAK",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			br := uint8(r.Intn(4))
 			loc := uint32(r.Intn(4))
 			typ := uint32(r.Intn(16))
 			addr := generateInt(cfg, r, 8)
-			if cfg.Mode == ifuzz.ModeLong64 {
+			if cfg.Mode == ifuzzimpl.ModeLong64 {
 				gen.mov64(regRAX, addr)
 			} else {
 				gen.mov32(regEAX, uint32(addr))
@@ -152,13 +153,13 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_LOAD_SEG",
-		Mode:   1<<ifuzz.ModeLast - 1,
+		Mode:   1<<ifuzzimpl.ModeLast - 1,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			sel := randSelector(r)
-			if cfg.Mode == ifuzz.ModeReal16 {
+			if cfg.Mode == ifuzzimpl.ModeReal16 {
 				sel = uint16(generateInt(cfg, r, 8)) >> 4
 			}
 			reg := uint8(r.Intn(6))
@@ -169,14 +170,14 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_FAR_JMP",
-		Mode:   1<<ifuzz.ModeLong64 | 1<<ifuzz.ModeProt32 | 1<<ifuzz.ModeProt16,
+		Mode:   1<<ifuzzimpl.ModeLong64 | 1<<ifuzzimpl.ModeProt32 | 1<<ifuzzimpl.ModeProt16,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			sel := randSelector(r)
 			off := generateInt(cfg, r, 4)
-			if cfg.Mode == ifuzz.ModeLong64 {
+			if cfg.Mode == ifuzzimpl.ModeLong64 {
 				gen.mov32toSPaddr(uint32(sel), 0)
 				gen.mov32toSPaddr(uint32(off), 2)
 				if r.Intn(2) == 0 {
@@ -190,7 +191,7 @@ func (insnset *InsnSetX86) initPseudo() {
 				} else {
 					gen.byte(0x9a) // lcall $imm16, $imm16/32
 				}
-				if cfg.Mode == ifuzz.ModeProt16 {
+				if cfg.Mode == ifuzzimpl.ModeProt16 {
 					gen.imm16(uint16(off))
 				} else {
 					gen.imm32(uint32(off))
@@ -202,10 +203,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_LTR_LLDT",
-		Mode:   1<<ifuzz.ModeLong64 | 1<<ifuzz.ModeProt32 | 1<<ifuzz.ModeProt16,
+		Mode:   1<<ifuzzimpl.ModeLong64 | 1<<ifuzzimpl.ModeProt32 | 1<<ifuzzimpl.ModeProt16,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			sel := randSelector(r)
 			gen.mov16(regAX, sel)
@@ -219,10 +220,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_LGIDT",
-		Mode:   1<<ifuzz.ModeLong64 | 1<<ifuzz.ModeProt32 | 1<<ifuzz.ModeProt16,
+		Mode:   1<<ifuzzimpl.ModeLong64 | 1<<ifuzzimpl.ModeProt32 | 1<<ifuzzimpl.ModeProt16,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			limit := uint32(generateInt(cfg, r, 2))
 			base := uint32(generateInt(cfg, r, 4))
@@ -240,10 +241,10 @@ func (insnset *InsnSetX86) initPseudo() {
 	})
 	insnset.Insns = append(insnset.Insns, &Insn{
 		Name:   "PSEUDO_HYPERCALL",
-		Mode:   1<<ifuzz.ModeLong64 | 1<<ifuzz.ModeProt32 | 1<<ifuzz.ModeProt16,
+		Mode:   1<<ifuzzimpl.ModeLong64 | 1<<ifuzzimpl.ModeProt32 | 1<<ifuzzimpl.ModeProt16,
 		Priv:   true,
 		Pseudo: true,
-		generator: func(cfg *ifuzz.Config, r *rand.Rand) []byte {
+		generator: func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte {
 			gen := makeGen(cfg, r)
 			switch r.Intn(2) {
 			case 0:
@@ -280,12 +281,12 @@ const (
 )
 
 type generator struct {
-	mode int
+	mode ifuzzimpl.Mode
 	r    *rand.Rand
 	text []byte
 }
 
-func makeGen(cfg *ifuzz.Config, r *rand.Rand) *generator {
+func makeGen(cfg *ifuzzimpl.Config, r *rand.Rand) *generator {
 	return &generator{
 		mode: cfg.Mode,
 		r:    r,
@@ -311,9 +312,9 @@ func (gen *generator) imm64(v uint64) {
 
 func (gen *generator) operand16() {
 	switch gen.mode {
-	case ifuzz.ModeLong64, ifuzz.ModeProt32:
+	case ifuzzimpl.ModeLong64, ifuzzimpl.ModeProt32:
 		gen.byte(0x66)
-	case ifuzz.ModeProt16, ifuzz.ModeReal16:
+	case ifuzzimpl.ModeProt16, ifuzzimpl.ModeReal16:
 	default:
 		panic("bad mode")
 	}
@@ -321,8 +322,8 @@ func (gen *generator) operand16() {
 
 func (gen *generator) operand32() {
 	switch gen.mode {
-	case ifuzz.ModeLong64, ifuzz.ModeProt32:
-	case ifuzz.ModeProt16, ifuzz.ModeReal16:
+	case ifuzzimpl.ModeLong64, ifuzzimpl.ModeProt32:
+	case ifuzzimpl.ModeProt16, ifuzzimpl.ModeReal16:
 		gen.byte(0x66)
 	default:
 		panic("bad mode")
@@ -331,8 +332,8 @@ func (gen *generator) operand32() {
 
 func (gen *generator) addr32() {
 	switch gen.mode {
-	case ifuzz.ModeLong64, ifuzz.ModeProt32:
-	case ifuzz.ModeProt16, ifuzz.ModeReal16:
+	case ifuzzimpl.ModeLong64, ifuzzimpl.ModeProt32:
+	case ifuzzimpl.ModeProt16, ifuzzimpl.ModeReal16:
 		gen.byte(0x67)
 	default:
 		panic("bad mode")
@@ -384,7 +385,7 @@ func (gen *generator) mov32(reg int, v uint32) {
 }
 
 func (gen *generator) mov64(reg int, v uint64) {
-	if gen.mode != ifuzz.ModeLong64 {
+	if gen.mode != ifuzzimpl.ModeLong64 {
 		panic("bad mode")
 	}
 	gen.byte(0x48)
diff --git a/pkg/ifuzz/x86/x86.go b/pkg/ifuzz/x86/x86.go
index 1583040ad..3e3ae845d 100644
--- a/pkg/ifuzz/x86/x86.go
+++ b/pkg/ifuzz/x86/x86.go
@@ -7,9 +7,9 @@
 package x86
 
 import (
-	"github.com/google/syzkaller/pkg/ifuzz"
-	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 	"math/rand"
+
+	"github.com/google/syzkaller/pkg/ifuzz/ifuzzimpl"
 )
 
 type Insn struct {
@@ -44,57 +44,48 @@ type Insn struct {
 	VexP       int8
 	Avx2Gather bool
 
-	generator func(cfg *ifuzz.Config, r *rand.Rand) []byte // for pseudo instructions
+	generator func(cfg *ifuzzimpl.Config, r *rand.Rand) []byte // for pseudo instructions
 }
 
-const (
-	typeExec = iota
-	typePriv
-	typeUser
-	typeAll
-	typeLast
-)
-
 type InsnSetX86 struct {
-	modeInsns [ifuzz.ModeLast][typeLast][]ifuzz.Insn
+	modeInsns [ifuzzimpl.ModeLast][ifuzzimpl.TypeLast][]ifuzzimpl.Insn
 	Insns     []*Insn
 }
 
 func Register(insns []*Insn) {
-	var insnset InsnSetX86
-
-	insnset.Insns = insns
-	if len(insnset.Insns) == 0 {
+	if len(insns) == 0 {
 		panic("no instructions")
 	}
+	insnset := &InsnSetX86{
+		Insns: insns,
+	}
 	insnset.initPseudo()
-	for mode := 0; mode < ifuzz.ModeLast; mode++ {
+	for mode := ifuzzimpl.Mode(0); mode < ifuzzimpl.ModeLast; mode++ {
 		for _, insn := range insnset.Insns {
 			if insn.Mode&(1<<uint(mode)) == 0 {
 				continue
 			}
 			if insn.Pseudo {
-				insnset.modeInsns[mode][typeExec] =
-					append(insnset.modeInsns[mode][typeExec], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypeExec] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeExec], insn)
 			} else if insn.Priv {
-				insnset.modeInsns[mode][typePriv] =
-					append(insnset.modeInsns[mode][typePriv], ifuzz.Insn(insn))
-				insnset.modeInsns[mode][typeAll] =
-					append(insnset.modeInsns[mode][typeAll], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypePriv] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypePriv], insn)
+				insnset.modeInsns[mode][ifuzzimpl.TypeAll] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeAll], insn)
 			} else {
-				insnset.modeInsns[mode][typeUser] =
-					append(insnset.modeInsns[mode][typeUser], ifuzz.Insn(insn))
-				insnset.modeInsns[mode][typeAll] =
-					append(insnset.modeInsns[mode][typeAll], ifuzz.Insn(insn))
+				insnset.modeInsns[mode][ifuzzimpl.TypeUser] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeUser], insn)
+				insnset.modeInsns[mode][ifuzzimpl.TypeAll] =
+					append(insnset.modeInsns[mode][ifuzzimpl.TypeAll], insn)
 			}
 		}
 	}
-
-	ifuzzimpl.Register(ifuzz.ArchX86, ifuzz.InsnSet(&insnset))
+	ifuzzimpl.Arches[ifuzzimpl.ArchX86] = insnset
 }
 
-func (insnset *InsnSetX86) GetInsns(mode, insntype int) []ifuzz.Insn {
-	return insnset.modeInsns[mode][insntype]
+func (insnset *InsnSetX86) GetInsns(mode ifuzzimpl.Mode, typ ifuzzimpl.Type) []ifuzzimpl.Insn {
+	return insnset.modeInsns[mode][typ]
 }
 
 func (insn Insn) GetName() string {
@@ -113,7 +104,7 @@ func (insn Insn) GetPseudo() bool {
 	return insn.Pseudo
 }
 
-func generateArg(cfg *ifuzz.Config, r *rand.Rand, size int) []byte {
+func generateArg(cfg *ifuzzimpl.Config, r *rand.Rand, size int) []byte {
 	v := generateInt(cfg, r, size)
 	arg := make([]byte, size)
 	for i := 0; i < size; i++ {
@@ -123,8 +114,8 @@ func generateArg(cfg *ifuzz.Config, r *rand.Rand, size int) []byte {
 	return arg
 }
 
-func (insn Insn) IsCompatible(cfg *ifuzz.Config) bool {
-	if cfg.Mode < 0 || cfg.Mode >= ifuzz.ModeLast {
+func (insn Insn) IsCompatible(cfg *ifuzzimpl.Config) bool {
+	if cfg.Mode < 0 || cfg.Mode >= ifuzzimpl.ModeLast {
 		panic("bad mode")
 	}
 	if insn.Priv && !cfg.Priv {
@@ -139,7 +130,7 @@ func (insn Insn) IsCompatible(cfg *ifuzz.Config) bool {
 	return true
 }
 
-func generateInt(cfg *ifuzz.Config, r *rand.Rand, size int) uint64 {
+func generateInt(cfg *ifuzzimpl.Config, r *rand.Rand, size int) uint64 {
 	if size != 1 && size != 2 && size != 4 && size != 8 {
 		panic("bad arg size")
 	}
@@ -154,7 +145,7 @@ func generateInt(cfg *ifuzz.Config, r *rand.Rand, size int) uint64 {
 	case x < 30:
 		v = uint64(r.Int63())
 	case x < 40:
-		v = ifuzz.SpecialNumbers[r.Intn(len(ifuzz.SpecialNumbers))]
+		v = ifuzzimpl.SpecialNumbers[r.Intn(len(ifuzzimpl.SpecialNumbers))]
 		if r.Intn(5) == 0 {
 			v += uint64(r.Intn(33)) - 16
 		}