prog: support disabled attribute

Update #477
Update #502

24 files changed, 187 insertions, 170 deletions

diff --git a/pkg/csource/csource_test.go b/pkg/csource/csource_test.go
index 78145c8fa..32ff9da28 100644
--- a/pkg/csource/csource_test.go
+++ b/pkg/csource/csource_test.go
@@ -62,7 +62,7 @@ func testTarget(t *testing.T, target *prog.Target, full bool) {
 	}
 	rs := rand.NewSource(seed)
 	t.Logf("seed=%v", seed)
-	p := target.Generate(rs, 10, nil)
+	p := target.Generate(rs, 10, target.DefaultChoiceTable())
 	// Turns out that fully minimized program can trigger new interesting warnings,
 	// e.g. about NULL arguments for functions that require non-NULL arguments in syz_ functions.
 	// We could append both AllSyzProg as-is and a minimized version of it,
@@ -166,7 +166,7 @@ func TestSysTests(t *testing.T) {
 func TestExecutorMacros(t *testing.T) {
 	// Ensure that executor does not mis-spell any of the SYZ_* macros.
 	target, _ := prog.GetTarget("test", "64")
-	p := target.Generate(rand.NewSource(0), 1, nil)
+	p := target.Generate(rand.NewSource(0), 1, target.DefaultChoiceTable())
 	expected := commonDefines(p, Options{})
 	expected["SYZ_EXECUTOR"] = true
 	expected["SYZ_HAVE_SETUP_LOOP"] = true
diff --git a/pkg/host/syscalls.go b/pkg/host/syscalls.go
index 17ec0f25a..d63c7ceef 100644
--- a/pkg/host/syscalls.go
+++ b/pkg/host/syscalls.go
@@ -21,38 +21,44 @@ func DetectSupportedSyscalls(target *prog.Target, sandbox string) (
 		for _, c := range target.Syscalls {
 			supported[c] = true
 		}
-		return supported, unsupported, nil
-	}
-	for _, c := range target.Syscalls {
-		ok, reason := false, ""
-		switch c.CallName {
-		case "syz_execute_func":
-			// syz_execute_func caused multiple problems:
-			// 1. First it lead to corpus exploision. The program used existing values in registers
-			// to pollute output area. We tried to zero registers (though, not reliably).
-			// 2. It lead to explosion again. The exact mechanics are unknown, here is one sample:
-			// syz_execute_func(&(0x7f0000000440)="f2af91930f0124eda133fa20430fbafce842f66188d0d4
-			//	430fc7f314c1ab5bf9e2f9660f3a0fae5e090000ba023c1fb63ac4817d73d74ec482310d46f44
-			//	9f216c863fa438036a91bdbae95aaaa420f383c02c401405c6bfd49d768d768f833fefbab6464
-			//	660f38323c8f26dbc1a1fe5ff6f6df0804f4c4efa59c0f01c4288ba6452e000054c4431d5cc100")
-			// 3. The code can also execute syscalls (and it is know to), but it's not subject to
-			// target.SanitizeCall. As the result it can do things that programs are not supposed to do.
-			// 4. Besides linux, corpus explosion also happens on freebsd and is clearly attributable
-			// to syz_execute_func based on corpus contents. Mechanics are also not known.
-			// It also did not cause finding of any new bugs (at least not that I know of).
-			// Let's disable it for now until we figure out how to resolve all these problems.
-			ok = false
-			reason = "always disabled for now"
-		default:
-			ok, reason = isSupported(c, target, sandbox)
-		}
-		if ok {
-			supported[c] = true
-		} else {
-			if reason == "" {
-				reason = "unknown"
+	} else {
+		for _, c := range target.Syscalls {
+			ok, reason := false, ""
+			switch c.CallName {
+			case "syz_execute_func":
+				// syz_execute_func caused multiple problems:
+				// 1. First it lead to corpus exploision. The program used existing values in registers
+				// to pollute output area. We tried to zero registers (though, not reliably).
+				// 2. It lead to explosion again. The exact mechanics are unknown, here is one sample:
+				// syz_execute_func(&(0x7f0000000440)="f2af91930f0124eda133fa20430fbafce842f66188d0d4
+				//	430fc7f314c1ab5bf9e2f9660f3a0fae5e090000ba023c1fb63ac4817d73d74ec482310d46f44
+				//	9f216c863fa438036a91bdbae95aaaa420f383c02c401405c6bfd49d768d768f833fefbab6464
+				//	660f38323c8f26dbc1a1fe5ff6f6df0804f4c4efa59c0f01c4288ba6452e000054c4431d5cc100")
+				// 3. The code can also execute syscalls (and it is know to), but it's not subject to
+				// target.SanitizeCall. As the result it can do things that programs are not supposed to do.
+				// 4. Besides linux, corpus explosion also happens on freebsd and is clearly attributable
+				// to syz_execute_func based on corpus contents. Mechanics are also not known.
+				// It also did not cause finding of any new bugs (at least not that I know of).
+				// Let's disable it for now until we figure out how to resolve all these problems.
+				ok = false
+				reason = "always disabled for now"
+			default:
+				ok, reason = isSupported(c, target, sandbox)
 			}
-			unsupported[c] = reason
+			if ok {
+				supported[c] = true
+			} else {
+				if reason == "" {
+					reason = "unknown"
+				}
+				unsupported[c] = reason
+			}
+		}
+	}
+	for c := range supported {
+		if c.Attrs.Disabled {
+			delete(supported, c)
+			unsupported[c] = "has disabled attribute in descriptions"
 		}
 	}
 	return supported, unsupported, nil
diff --git a/pkg/mgrconfig/load.go b/pkg/mgrconfig/load.go
index 4e4136362..c17f7cd15 100644
--- a/pkg/mgrconfig/load.go
+++ b/pkg/mgrconfig/load.go
@@ -216,6 +216,11 @@ func ParseEnabledSyscalls(target *prog.Target, enabled, disabled []string) ([]in
 			syscalls[call.ID] = true
 		}
 	}
+	for call := range syscalls {
+		if target.Syscalls[call].Attrs.Disabled {
+			delete(syscalls, call)
+		}
+	}
 	for _, c := range disabled {
 		n := 0
 		for _, call := range target.Syscalls {
diff --git a/prog/any_test.go b/prog/any_test.go
index e481ef1c1..f021eeda7 100644
--- a/prog/any_test.go
+++ b/prog/any_test.go
@@ -12,6 +12,7 @@ import (
 
 func TestIsComplexPtr(t *testing.T) {
 	target, rs, _ := initRandomTargetTest(t, "linux", "amd64")
+	ct := target.DefaultChoiceTable()
 	iters := 10
 	if testing.Short() {
 		iters = 1
@@ -19,8 +20,11 @@ func TestIsComplexPtr(t *testing.T) {
 	r := newRand(target, rs)
 	compl := make(map[string]bool)
 	for _, meta := range target.Syscalls {
+		if meta.Attrs.Disabled {
+			continue
+		}
 		for i := 0; i < iters; i++ {
-			s := newState(target, nil, nil)
+			s := newState(target, ct, nil)
 			calls := r.generateParticularCall(s, meta)
 			p := &Prog{Target: target, Calls: calls}
 			for _, arg := range p.complexPtrs() {
diff --git a/prog/checksum_test.go b/prog/checksum_test.go
index 75e18ab70..d8fb849bb 100644
--- a/prog/checksum_test.go
+++ b/prog/checksum_test.go
@@ -12,13 +12,14 @@ import (
 
 func TestChecksumCalcRandom(t *testing.T) {
 	target, rs, iters := InitTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		for _, call := range p.Calls {
 			CalcChecksumsCall(call)
 		}
 		for try := 0; try <= 10; try++ {
-			p.Mutate(rs, 10, nil, nil)
+			p.Mutate(rs, 10, ct, nil)
 			for _, call := range p.Calls {
 				CalcChecksumsCall(call)
 			}
diff --git a/prog/encoding_test.go b/prog/encoding_test.go
index 2464f35da..a38e9deab 100644
--- a/prog/encoding_test.go
+++ b/prog/encoding_test.go
@@ -114,9 +114,10 @@ func TestCallSet(t *testing.T) {
 
 func TestCallSetRandom(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
 		const ncalls = 10
-		p := target.Generate(rs, ncalls, nil)
+		p := target.Generate(rs, ncalls, ct)
 		calls0 := make(map[string]struct{})
 		for _, c := range p.Calls {
 			calls0[c.Meta.Name] = struct{}{}
@@ -328,10 +329,11 @@ func TestSerializeDeserialize(t *testing.T) {
 
 func TestSerializeDeserializeRandom(t *testing.T) {
 	testEachTargetRandom(t, func(t *testing.T, target *Target, rs rand.Source, iters int) {
+		ct := target.DefaultChoiceTable()
 		data0 := make([]byte, ExecBufferSize)
 		data1 := make([]byte, ExecBufferSize)
 		for i := 0; i < iters; i++ {
-			p0 := target.Generate(rs, 10, nil)
+			p0 := target.Generate(rs, 10, ct)
 			if ok, _, _ := testSerializeDeserialize(t, p0, data0, data1); ok {
 				continue
 			}
diff --git a/prog/encodingexec_test.go b/prog/encodingexec_test.go
index 6e2e5f61f..7114ab30f 100644
--- a/prog/encodingexec_test.go
+++ b/prog/encodingexec_test.go
@@ -13,9 +13,10 @@ import (
 
 func TestSerializeForExecRandom(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	buf := make([]byte, ExecBufferSize)
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		n, err := p.SerializeForExec(buf)
 		if err != nil {
 			t.Fatalf("failed to serialize: %v", err)
diff --git a/prog/hints_test.go b/prog/hints_test.go
index 852f7bd86..54b6569a2 100644
--- a/prog/hints_test.go
+++ b/prog/hints_test.go
@@ -478,10 +478,11 @@ func TestHintsShrinkExpand(t *testing.T) {
 
 func TestHintsRandom(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	iters /= 10 // the test takes long
 	r := newRand(target, rs)
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 5, nil)
+		p := target.Generate(rs, 5, ct)
 		for i, c := range p.Calls {
 			vals := extractValues(c)
 			for j := 0; j < 5; j++ {
@@ -570,7 +571,8 @@ func BenchmarkHints(b *testing.B) {
 	defer cleanup()
 	rs := rand.NewSource(0)
 	r := newRand(target, rs)
-	p := target.Generate(rs, 30, nil)
+	ct := target.DefaultChoiceTable()
+	p := target.Generate(rs, 30, ct)
 	comps := make([]CompMap, len(p.Calls))
 	for i, c := range p.Calls {
 		vals := extractValues(c)
diff --git a/prog/minimization_test.go b/prog/minimization_test.go
index 3fde47c77..36b65763d 100644
--- a/prog/minimization_test.go
+++ b/prog/minimization_test.go
@@ -176,10 +176,11 @@ func TestMinimize(t *testing.T) {
 func TestMinimizeRandom(t *testing.T) {
 	target, rs, iters := initTest(t)
 	iters /= 10 // Long test.
+	ct := target.DefaultChoiceTable()
 	r := rand.New(rs)
 	for i := 0; i < iters; i++ {
 		for _, crash := range []bool{false, true} {
-			p := target.Generate(rs, 5, nil)
+			p := target.Generate(rs, 5, ct)
 			copyP := p.Clone()
 			minP, _ := Minimize(p, len(p.Calls)-1, crash, func(p1 *Prog, callIndex int) bool {
 				if r.Intn(2) == 0 {
@@ -199,9 +200,10 @@ func TestMinimizeRandom(t *testing.T) {
 
 func TestMinimizeCallIndex(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	r := rand.New(rs)
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 5, nil)
+		p := target.Generate(rs, 5, ct)
 		ci := r.Intn(len(p.Calls))
 		p1, ci1 := Minimize(p, ci, r.Intn(2) == 0, func(p1 *Prog, callIndex int) bool {
 			return r.Intn(2) == 0
diff --git a/prog/mutation_test.go b/prog/mutation_test.go
index 7708a286f..a64cc6010 100644
--- a/prog/mutation_test.go
+++ b/prog/mutation_test.go
@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"math"
 	"math/rand"
-	"sync"
 	"testing"
 )
 
@@ -155,9 +154,9 @@ func TestMutateArgument(t *testing.T) {
 func TestSizeMutateArg(t *testing.T) {
 	target, rs, iters := initRandomTargetTest(t, "test", "64")
 	r := newRand(target, rs)
-	ct := target.BuildChoiceTable(nil, nil)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < 100; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		for it := 0; it < iters; it++ {
 			p1 := p.Clone()
 			ctx := &mutator{
@@ -217,8 +216,9 @@ func TestRandomChoice(t *testing.T) {
 
 func TestClone(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		p1 := p.Clone()
 		data := p.Serialize()
 		data1 := p1.Serialize()
@@ -230,15 +230,16 @@ func TestClone(t *testing.T) {
 
 func TestMutateRandom(t *testing.T) {
 	testEachTargetRandom(t, func(t *testing.T, target *Target, rs rand.Source, iters int) {
+		ct := target.DefaultChoiceTable()
 	next:
 		for i := 0; i < iters; i++ {
-			p := target.Generate(rs, 10, nil)
+			p := target.Generate(rs, 10, ct)
 			data0 := p.Serialize()
 			p1 := p.Clone()
 			// There is a chance that mutation will produce the same program.
 			// So we check that at least 1 out of 20 mutations actually change the program.
 			for try := 0; try < 20; try++ {
-				p1.Mutate(rs, 10, nil, nil)
+				p1.Mutate(rs, 10, ct, nil)
 				data := p.Serialize()
 				if !bytes.Equal(data0, data) {
 					t.Fatalf("program changed after mutate\noriginal:\n%s\n\nnew:\n%s\n",
@@ -260,14 +261,15 @@ func TestMutateRandom(t *testing.T) {
 
 func TestMutateCorpus(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	var corpus []*Prog
 	for i := 0; i < 100; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		corpus = append(corpus, p)
 	}
 	for i := 0; i < iters; i++ {
-		p1 := target.Generate(rs, 10, nil)
-		p1.Mutate(rs, 10, nil, corpus)
+		p1 := target.Generate(rs, 10, ct)
+		p1.Mutate(rs, 10, ct, corpus)
 	}
 }
 
@@ -402,9 +404,9 @@ mutate_rangedbuffer(&(0x7f00000000c0)=""/11)
 func BenchmarkMutate(b *testing.B) {
 	target, cleanup := initBench(b)
 	defer cleanup()
-	ct := linuxAmd64ChoiceTable(target)
+	ct := target.DefaultChoiceTable()
 	const progLen = 30
-	p := target.Generate(rand.NewSource(0), progLen, nil)
+	p := target.Generate(rand.NewSource(0), progLen, ct)
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
 		rs := rand.NewSource(0)
@@ -417,7 +419,7 @@ func BenchmarkMutate(b *testing.B) {
 func BenchmarkGenerate(b *testing.B) {
 	target, cleanup := initBench(b)
 	defer cleanup()
-	ct := linuxAmd64ChoiceTable(target)
+	ct := target.DefaultChoiceTable()
 	const progLen = 30
 	b.ResetTimer()
 	b.RunParallel(func(pb *testing.PB) {
@@ -428,18 +430,6 @@ func BenchmarkGenerate(b *testing.B) {
 	})
 }
 
-var (
-	linuxCTOnce sync.Once
-	linuxCT     *ChoiceTable
-)
-
-func linuxAmd64ChoiceTable(target *Target) *ChoiceTable {
-	linuxCTOnce.Do(func() {
-		linuxCT = target.BuildChoiceTable(target.CalculatePriorities(nil), nil)
-	})
-	return linuxCT
-}
-
 func runMutationTests(t *testing.T, tests [][2]string, valid bool) {
 	target := initTargetTest(t, "test", "64")
 	for ti, test := range tests {
diff --git a/prog/prio.go b/prog/prio.go
index 648af0422..ccdab7bda 100644
--- a/prog/prio.go
+++ b/prog/prio.go
@@ -26,13 +26,15 @@ import (
 
 func (target *Target) CalculatePriorities(corpus []*Prog) [][]float32 {
 	static := target.calcStaticPriorities()
-	dynamic := target.calcDynamicPrio(corpus)
-	for i, prios := range static {
-		for j, p := range prios {
-			dynamic[i][j] *= p
+	if len(corpus) != 0 {
+		dynamic := target.calcDynamicPrio(corpus)
+		for i, prios := range dynamic {
+			for j, p := range prios {
+				static[i][j] *= p
+			}
 		}
 	}
-	return dynamic
+	return static
 }
 
 func (target *Target) calcStaticPriorities() [][]float32 {
@@ -200,29 +202,41 @@ func normalizePrio(prios [][]float32) {
 // ChooseTable allows to do a weighted choice of a syscall for a given syscall
 // based on call-to-call priorities and a set of enabled syscalls.
 type ChoiceTable struct {
-	target       *Target
-	run          [][]int
-	enabledCalls []*Syscall
-	enabled      map[*Syscall]bool
+	target *Target
+	runs   [][]int
+	calls  []*Syscall
 }
 
-func (target *Target) BuildChoiceTable(prios [][]float32, enabled map[*Syscall]bool) *ChoiceTable {
+func (target *Target) BuildChoiceTable(corpus []*Prog, enabled map[*Syscall]bool) *ChoiceTable {
 	if enabled == nil {
 		enabled = make(map[*Syscall]bool)
 		for _, c := range target.Syscalls {
 			enabled[c] = true
 		}
 	}
+	for call := range enabled {
+		if call.Attrs.Disabled {
+			delete(enabled, call)
+		}
+	}
 	var enabledCalls []*Syscall
 	for c := range enabled {
 		enabledCalls = append(enabledCalls, c)
 	}
 	if len(enabledCalls) == 0 {
-		panic(fmt.Sprintf("empty enabledCalls, len(target.Syscalls)=%v", len(target.Syscalls)))
+		panic("no syscalls enabled")
 	}
 	sort.Slice(enabledCalls, func(i, j int) bool {
 		return enabledCalls[i].ID < enabledCalls[j].ID
 	})
+	for _, p := range corpus {
+		for _, call := range p.Calls {
+			if !enabled[call.Meta] {
+				panic(fmt.Sprintf("corpus contains disabled syscall %v", call.Meta.Name))
+			}
+		}
+	}
+	prios := target.CalculatePriorities(corpus)
 	run := make([][]int, len(target.Syscalls))
 	for i := range run {
 		if !enabled[target.Syscalls[i]] {
@@ -232,31 +246,30 @@ func (target *Target) BuildChoiceTable(prios [][]float32, enabled map[*Syscall]b
 		sum := 0
 		for j := range run[i] {
 			if enabled[target.Syscalls[j]] {
-				w := 1
-				if prios != nil {
-					w = int(prios[i][j] * 1000)
-				}
-				sum += w
+				sum += int(prios[i][j] * 1000)
 			}
 			run[i][j] = sum
 		}
 	}
-	return &ChoiceTable{target, run, enabledCalls, enabled}
+	return &ChoiceTable{target, run, enabledCalls}
 }
 
-func (ct *ChoiceTable) Choose(r *rand.Rand, call int) int {
-	if call < 0 {
-		return ct.enabledCalls[r.Intn(len(ct.enabledCalls))].ID
+func (ct *ChoiceTable) enabled(call int) bool {
+	return ct.runs[call] != nil
+}
+
+func (ct *ChoiceTable) choose(r *rand.Rand, bias int) int {
+	if bias < 0 {
+		bias = ct.calls[r.Intn(len(ct.calls))].ID
 	}
-	run := ct.run[call]
-	if run == nil {
-		return ct.enabledCalls[r.Intn(len(ct.enabledCalls))].ID
+	if !ct.enabled(bias) {
+		panic("bias to disabled syscall")
 	}
-	for {
-		x := r.Intn(run[len(run)-1]) + 1
-		i := sort.SearchInts(run, x)
-		if ct.enabled[ct.target.Syscalls[i]] {
-			return i
-		}
+	run := ct.runs[bias]
+	x := r.Intn(run[len(run)-1]) + 1
+	res := sort.SearchInts(run, x)
+	if !ct.enabled(res) {
+		panic("selected disabled syscall")
 	}
+	return res
 }
diff --git a/prog/prio_test.go b/prog/prio_test.go
index 2fd059910..29ffa26d7 100644
--- a/prog/prio_test.go
+++ b/prog/prio_test.go
@@ -7,8 +7,6 @@ import (
 	"math/rand"
 	"reflect"
 	"testing"
-
-	"github.com/google/go-cmp/cmp"
 )
 
 func TestNormalizePrio(t *testing.T) {
@@ -30,36 +28,6 @@ func TestNormalizePrio(t *testing.T) {
 	}
 }
 
-// TestPrioChoice tests that we select all syscalls with equal probability.
-func TestPrioChoice(t *testing.T) {
-	t.Parallel()
-	target := &Target{
-		Syscalls: []*Syscall{
-			{ID: 0},
-			{ID: 1},
-			{ID: 2},
-			{ID: 3},
-		},
-	}
-	prios := [][]float32{
-		{1, 1, 1, 1},
-		{1, 1, 1, 1},
-		{1, 1, 1, 1},
-		{1, 1, 1, 1},
-	}
-	ct := target.BuildChoiceTable(prios, nil)
-	r := rand.New(rand.NewSource(0))
-	var res [4]int
-	for i := 0; i < 10000; i++ {
-		res[ct.Choose(r, 0)]++
-	}
-	// If this fails too frequently we can do some ranges, but for now it's just hardcoded.
-	want := [4]int{2552, 2459, 2491, 2498}
-	if diff := cmp.Diff(res, want); diff != "" {
-		t.Fatal(diff)
-	}
-}
-
 // Test static priorities assigned based on argument direction.
 func TestStaticPriorities(t *testing.T) {
 	target, rs, iters := initTest(t)
@@ -73,7 +41,7 @@ func TestStaticPriorities(t *testing.T) {
 		{"open", "read", "write", "mmap"},
 		{"socket", "listen", "setsockopt"},
 	}
-	ct := target.BuildChoiceTable(target.CalculatePriorities(nil), nil)
+	ct := target.DefaultChoiceTable()
 	r := rand.New(rs)
 	for _, syscalls := range tests {
 		// Counts the number of times a call is chosen after a call that creates a resource (referenceCall).
@@ -82,7 +50,7 @@ func TestStaticPriorities(t *testing.T) {
 		for _, call := range syscalls {
 			count := 0
 			for it := 0; it < iters*10000; it++ {
-				chosenCall := target.Syscalls[ct.Choose(r, target.SyscallMap[call].ID)].Name
+				chosenCall := target.Syscalls[ct.choose(r, target.SyscallMap[call].ID)].Name
 				if call == referenceCall {
 					counter[chosenCall]++
 				} else if chosenCall == referenceCall {
diff --git a/prog/prog_test.go b/prog/prog_test.go
index 6374b6d25..d04b08e17 100644
--- a/prog/prog_test.go
+++ b/prog/prog_test.go
@@ -13,8 +13,9 @@ import (
 
 func TestGeneration(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
-		target.Generate(rs, 20, nil)
+		target.Generate(rs, 20, ct)
 	}
 }
 
@@ -32,6 +33,9 @@ func TestDefault(t *testing.T) {
 func TestDefaultCallArgs(t *testing.T) {
 	target, _, _ := initTest(t)
 	for _, meta := range target.SyscallMap {
+		if meta.Attrs.Disabled {
+			continue
+		}
 		// Ensure that we can restore all arguments of all calls.
 		prog := fmt.Sprintf("%v()", meta.Name)
 		p, err := target.Deserialize([]byte(prog), NonStrict)
@@ -46,8 +50,9 @@ func TestDefaultCallArgs(t *testing.T) {
 
 func testSerialize(t *testing.T, verbose bool) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		var data []byte
 		mode := NonStrict
 		if verbose {
@@ -88,11 +93,12 @@ func TestSerializeVerbose(t *testing.T) {
 
 func TestVmaType(t *testing.T) {
 	target, rs, iters := initRandomTargetTest(t, "test", "64")
+	ct := target.DefaultChoiceTable()
 	meta := target.SyscallMap["test$vma0"]
 	r := newRand(target, rs)
 	pageSize := target.PageSize
 	for i := 0; i < iters; i++ {
-		s := newState(target, nil, nil)
+		s := newState(target, ct, nil)
 		calls := r.generateParticularCall(s, meta)
 		c := calls[len(calls)-1]
 		if c.Meta.Name != "test$vma0" {
@@ -161,20 +167,21 @@ func TestCrossTarget(t *testing.T) {
 }
 
 func testCrossTarget(t *testing.T, target *Target, crossTargets []*Target) {
+	ct := target.DefaultChoiceTable()
 	rs := randSource(t)
 	iters := 100
 	if testing.Short() {
 		iters /= 10
 	}
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 20, nil)
+		p := target.Generate(rs, 20, ct)
 		testCrossArchProg(t, p, crossTargets)
 		p, err := target.Deserialize(p.Serialize(), NonStrict)
 		if err != nil {
 			t.Fatal(err)
 		}
 		testCrossArchProg(t, p, crossTargets)
-		p.Mutate(rs, 20, nil, nil)
+		p.Mutate(rs, 20, ct, nil)
 		testCrossArchProg(t, p, crossTargets)
 		p, _ = Minimize(p, -1, false, func(*Prog, int) bool {
 			return rs.Int63()%2 == 0
@@ -197,6 +204,8 @@ func testCrossArchProg(t *testing.T, p *Prog, crossTargets []*Target) {
 
 func TestSpecialStructs(t *testing.T) {
 	testEachTargetRandom(t, func(t *testing.T, target *Target, rs rand.Source, iters int) {
+		_ = target.GenerateAllSyzProg(rs)
+		ct := target.DefaultChoiceTable()
 		for special, gen := range target.SpecialTypes {
 			t.Run(special, func(t *testing.T) {
 				var typ Type
@@ -216,7 +225,7 @@ func TestSpecialStructs(t *testing.T) {
 				if typ == nil {
 					t.Fatal("can't find struct description")
 				}
-				g := &Gen{newRand(target, rs), newState(target, nil, nil)}
+				g := &Gen{newRand(target, rs), newState(target, ct, nil)}
 				for i := 0; i < iters/len(target.SpecialTypes); i++ {
 					var arg Arg
 					for i := 0; i < 2; i++ {
@@ -441,8 +450,9 @@ fallback$0()
 
 func TestSanitizeRandom(t *testing.T) {
 	testEachTargetRandom(t, func(t *testing.T, target *Target, rs rand.Source, iters int) {
+		ct := target.DefaultChoiceTable()
 		for i := 0; i < iters; i++ {
-			p := target.Generate(rs, 10, nil)
+			p := target.Generate(rs, 10, ct)
 			s0 := string(p.Serialize())
 			p.sanitizeFix()
 			s1 := string(p.Serialize())
diff --git a/prog/rand.go b/prog/rand.go
index 135469fe7..150f4b266 100644
--- a/prog/rand.go
+++ b/prog/rand.go
@@ -379,10 +379,9 @@ func (r *randGen) createResource(s *state, res *ResourceType, dir Dir) (arg Arg,
 	// TODO: reduce priority of less specialized ctors.
 	var metas []*Syscall
 	for _, meta := range metas0 {
-		if s.ct == nil || s.ct.run[meta.ID] == nil {
-			continue
+		if s.ct.enabled(meta.ID) {
+			metas = append(metas, meta)
 		}
-		metas = append(metas, meta)
 	}
 	if len(metas) == 0 {
 		return res.DefaultArg(dir), nil
@@ -537,19 +536,12 @@ func (r *randGen) nOutOf(n, outOf int) bool {
 }
 
 func (r *randGen) generateCall(s *state, p *Prog, insertionPoint int) []*Call {
-	idx := 0
-	if s.ct == nil {
-		idx = r.Intn(len(r.target.Syscalls))
-	} else if insertionPoint <= 0 {
-		idx = s.ct.enabledCalls[r.Intn(len(s.ct.enabledCalls))].ID
-	} else {
-		call := -1
-		if len(p.Calls) != 0 {
-			// Choosing the base call is based on the insertion point of the new calls sequence.
-			call = p.Calls[r.Intn(insertionPoint)].Meta.ID
-		}
-		idx = s.ct.Choose(r.Rand, call)
+	biasCall := -1
+	if insertionPoint > 0 {
+		// Choosing the base call is based on the insertion point of the new calls sequence.
+		biasCall = p.Calls[r.Intn(insertionPoint)].Meta.ID
 	}
+	idx := s.ct.choose(r.Rand, biasCall)
 	meta := r.target.Syscalls[idx]
 	return r.generateParticularCall(s, meta)
 }
@@ -573,7 +565,7 @@ func (target *Target) GenerateAllSyzProg(rs rand.Source) *Prog {
 		Target: target,
 	}
 	r := newRand(target, rs)
-	s := newState(target, nil, nil)
+	s := newState(target, target.DefaultChoiceTable(), nil)
 	handled := make(map[string]bool)
 	for _, meta := range target.Syscalls {
 		if !strings.HasPrefix(meta.CallName, "syz_") || handled[meta.CallName] {
diff --git a/prog/rand_test.go b/prog/rand_test.go
index da0871505..960f9735f 100644
--- a/prog/rand_test.go
+++ b/prog/rand_test.go
@@ -31,13 +31,14 @@ func TestNotEscaping(t *testing.T) {
 func TestDeterminism(t *testing.T) {
 	target, rs, iters := initTest(t)
 	iters /= 10 // takes too long
+	ct := target.DefaultChoiceTable()
 	var corpus []*Prog
 	for i := 0; i < iters; i++ {
 		seed := rs.Int63()
 		rs1 := rand.NewSource(seed)
-		p1 := generateProg(t, target, rs1, corpus)
+		p1 := generateProg(t, target, rs1, ct, corpus)
 		rs2 := rand.NewSource(seed)
-		p2 := generateProg(t, target, rs2, corpus)
+		p2 := generateProg(t, target, rs2, ct, corpus)
 		ps1 := string(p1.Serialize())
 		ps2 := string(p2.Serialize())
 		r1 := rs1.Int63()
@@ -49,9 +50,9 @@ func TestDeterminism(t *testing.T) {
 	}
 }
 
-func generateProg(t *testing.T, target *Target, rs rand.Source, corpus []*Prog) *Prog {
-	p := target.Generate(rs, 5, nil)
-	p.Mutate(rs, 10, nil, corpus)
+func generateProg(t *testing.T, target *Target, rs rand.Source, ct *ChoiceTable, corpus []*Prog) *Prog {
+	p := target.Generate(rs, 5, ct)
+	p.Mutate(rs, 10, ct, corpus)
 	for i, c := range p.Calls {
 		comps := make(CompMap)
 		for v := range extractValues(c) {
diff --git a/prog/size_test.go b/prog/size_test.go
index 49945273b..6e8a28c4d 100644
--- a/prog/size_test.go
+++ b/prog/size_test.go
@@ -10,8 +10,9 @@ import (
 
 func TestAssignSizeRandom(t *testing.T) {
 	target, rs, iters := initTest(t)
+	ct := target.DefaultChoiceTable()
 	for i := 0; i < iters; i++ {
-		p := target.Generate(rs, 10, nil)
+		p := target.Generate(rs, 10, ct)
 		data0 := p.Serialize()
 		for _, call := range p.Calls {
 			target.assignSizesCall(call)
@@ -19,7 +20,7 @@ func TestAssignSizeRandom(t *testing.T) {
 		if data1 := p.Serialize(); !bytes.Equal(data0, data1) {
 			t.Fatalf("different lens assigned, initial:\n%s\nnew:\n%s\n", data0, data1)
 		}
-		p.Mutate(rs, 10, nil, nil)
+		p.Mutate(rs, 10, ct, nil)
 		p.Serialize()
 		for _, call := range p.Calls {
 			target.assignSizesCall(call)
diff --git a/prog/target.go b/prog/target.go
index 8999f25ac..af03dc47f 100644
--- a/prog/target.go
+++ b/prog/target.go
@@ -65,6 +65,10 @@ type Target struct {
 	// Maps resource name to a list of calls that can create the resource.
 	resourceCtors map[string][]*Syscall
 	any           anyTypes
+
+	// The default ChoiceTable is used only by tests and utilities, so we initialize it lazily.
+	defaultOnce        sync.Once
+	defaultChoiceTable *ChoiceTable
 }
 
 const maxSpecialPointers = 16
@@ -195,6 +199,13 @@ func restoreLinks(syscalls []*Syscall, resources []*ResourceDesc, types []Type)
 	return resourceMap
 }
 
+func (target *Target) DefaultChoiceTable() *ChoiceTable {
+	target.defaultOnce.Do(func() {
+		target.defaultChoiceTable = target.BuildChoiceTable(nil, nil)
+	})
+	return target.defaultChoiceTable
+}
+
 type Gen struct {
 	r *randGen
 	s *state
diff --git a/prog/test/fuzz.go b/prog/test/fuzz.go
index e86509237..f3742f6c3 100644
--- a/prog/test/fuzz.go
+++ b/prog/test/fuzz.go
@@ -52,7 +52,7 @@ func FuzzDeserialize(data []byte) int {
 			panic(err)
 		}
 	}
-	p3.Mutate(rand.NewSource(0), 3, nil, nil)
+	p3.Mutate(rand.NewSource(0), 3, fuzzChoiceTable, nil)
 	return 0
 }
 
@@ -64,11 +64,11 @@ func FuzzParseLog(data []byte) int {
 }
 
 var fuzzBuffer = make([]byte, prog.ExecBufferSize)
-var fuzzTarget = func() *prog.Target {
+var fuzzTarget, fuzzChoiceTable = func() (*prog.Target, *prog.ChoiceTable) {
 	prog.Debug()
 	target, err := prog.GetTarget("test", "64")
 	if err != nil {
 		panic(err)
 	}
-	return target
+	return target, target.DefaultChoiceTable()
 }()
diff --git a/prog/validation.go b/prog/validation.go
index e4613600c..e0e2eaaf7 100644
--- a/prog/validation.go
+++ b/prog/validation.go
@@ -50,6 +50,9 @@ func (p *Prog) validate() error {
 }
 
 func (ctx *validCtx) validateCall(c *Call) error {
+	if c.Meta.Attrs.Disabled {
+		return fmt.Errorf("use of a disabled call")
+	}
 	if len(c.Args) != len(c.Meta.Args) {
 		return fmt.Errorf("wrong number of arguments, want %v, got %v",
 			len(c.Meta.Args), len(c.Args))
diff --git a/sys/test/test.txt b/sys/test/test.txt
index 1fa8406d1..68eb4f8df 100644
--- a/sys/test/test.txt
+++ b/sys/test/test.txt
@@ -797,3 +797,11 @@ auto_struct0 {
 	f1	const[0x43, int32]
 	f2	int32
 }
+
+# Attributes
+
+resource disabled_resource[int32]
+
+disabled0() (disabled)
+disabled1() disabled_resource (disabled)
+disabled2(a disabled_resource) (disabled)
diff --git a/syz-fuzzer/fuzzer.go b/syz-fuzzer/fuzzer.go
index b6e8be4b4..3694190a1 100644
--- a/syz-fuzzer/fuzzer.go
+++ b/syz-fuzzer/fuzzer.go
@@ -247,8 +247,7 @@ func main() {
 	for _, id := range r.CheckResult.EnabledCalls[sandbox] {
 		calls[target.Syscalls[id]] = true
 	}
-	prios := target.CalculatePriorities(fuzzer.corpus)
-	fuzzer.choiceTable = target.BuildChoiceTable(prios, calls)
+	fuzzer.choiceTable = target.BuildChoiceTable(fuzzer.corpus, calls)
 
 	for pid := 0; pid < *flagProcs; pid++ {
 		proc, err := newProc(fuzzer, pid)
diff --git a/syz-fuzzer/fuzzer_test.go b/syz-fuzzer/fuzzer_test.go
index 41887896a..916e75ef5 100644
--- a/syz-fuzzer/fuzzer_test.go
+++ b/syz-fuzzer/fuzzer_test.go
@@ -79,7 +79,7 @@ func TestAddInputConcurrency(t *testing.T) {
 }
 
 func generateInput(target *prog.Target, rs rand.Source, ncalls int, sizeSig int) (inp InputTest) {
-	inp.p = target.Generate(rs, ncalls, nil)
+	inp.p = target.Generate(rs, ncalls, target.DefaultChoiceTable())
 	var raw []uint32
 	for i := 1; i <= sizeSig; i++ {
 		raw = append(raw, uint32(i))
diff --git a/tools/syz-mutate/mutate.go b/tools/syz-mutate/mutate.go
index 3dcc446c6..af92e14a1 100644
--- a/tools/syz-mutate/mutate.go
+++ b/tools/syz-mutate/mutate.go
@@ -64,8 +64,7 @@ func main() {
 		os.Exit(1)
 	}
 	rs := rand.NewSource(seed)
-	prios := target.CalculatePriorities(corpus)
-	ct := target.BuildChoiceTable(prios, syscalls)
+	ct := target.BuildChoiceTable(corpus, syscalls)
 	var p *prog.Prog
 	if flag.NArg() == 0 {
 		p = target.Generate(rs, *flagLen, ct)
diff --git a/tools/syz-stress/stress.go b/tools/syz-stress/stress.go
index 18d4fa872..b2fa4cb8e 100644
--- a/tools/syz-stress/stress.go
+++ b/tools/syz-stress/stress.go
@@ -74,8 +74,7 @@ func main() {
 		syscalls = strings.Split(*flagSyscalls, ",")
 	}
 	calls := buildCallList(target, syscalls)
-	prios := target.CalculatePriorities(corpus)
-	ct := target.BuildChoiceTable(prios, calls)
+	ct := target.BuildChoiceTable(corpus, calls)
 
 	config, execOpts, err := createIPCConfig(target, features, featuresFlags)
 	if err != nil {