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// 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 compiler
import (
"fmt"
"strings"
"github.com/google/syzkaller/pkg/ast"
"github.com/google/syzkaller/prog"
"github.com/google/syzkaller/sys/targets"
)
type ConstInfo struct {
File string
Consts []string
Includes []string
Incdirs []string
Defines map[string]string
}
func ExtractConsts(desc *ast.Description, target *targets.Target, eh ast.ErrorHandler) map[string]*ConstInfo {
res := Compile(desc, nil, target, eh)
if res == nil {
return nil
}
return res.fileConsts
}
// FabricateSyscallConsts adds syscall number constants to consts map.
// Used for test OS to not bother specifying consts for all syscalls.
func FabricateSyscallConsts(target *targets.Target, constInfo map[string]*ConstInfo, consts map[string]uint64) {
if !target.SyscallNumbers {
return
}
for _, info := range constInfo {
for _, name := range info.Consts {
if strings.HasPrefix(name, target.SyscallPrefix) {
consts[name] = 0
}
}
}
}
// extractConsts returns list of literal constants and other info required for const value extraction.
func (comp *compiler) extractConsts() map[string]*ConstInfo {
infos := make(map[string]*constInfo)
for _, decl := range comp.desc.Nodes {
pos, _, _ := decl.Info()
info := getConstInfo(infos, pos)
switch n := decl.(type) {
case *ast.Include:
info.includeArray = append(info.includeArray, n.File.Value)
case *ast.Incdir:
info.incdirArray = append(info.incdirArray, n.Dir.Value)
case *ast.Define:
v := fmt.Sprint(n.Value.Value)
switch {
case n.Value.CExpr != "":
v = n.Value.CExpr
case n.Value.Ident != "":
v = n.Value.Ident
}
name := n.Name.Name
if _, builtin := comp.builtinConsts[name]; builtin {
comp.error(pos, "redefining builtin const %v", name)
}
info.defines[name] = v
comp.addConst(infos, pos, name)
case *ast.Call:
if comp.target.SyscallNumbers && !strings.HasPrefix(n.CallName, "syz_") {
comp.addConst(infos, pos, comp.target.SyscallPrefix+n.CallName)
}
for _, attr := range n.Attrs {
if callAttrs[attr.Ident].HasArg {
comp.addConst(infos, attr.Pos, attr.Args[0].Ident)
}
}
case *ast.Struct:
for _, attr := range n.Attrs {
if structOrUnionAttrs(n)[attr.Ident].HasArg {
comp.addConst(infos, attr.Pos, attr.Args[0].Ident)
}
}
}
switch decl.(type) {
case *ast.Call, *ast.Struct, *ast.Resource, *ast.TypeDef:
comp.extractTypeConsts(infos, decl)
}
}
comp.desc.Walk(ast.Recursive(func(n0 ast.Node) {
if n, ok := n0.(*ast.Int); ok {
comp.addConst(infos, n.Pos, n.Ident)
}
}))
return convertConstInfo(infos)
}
func (comp *compiler) extractTypeConsts(infos map[string]*constInfo, n ast.Node) {
comp.foreachType(n, func(t *ast.Type, desc *typeDesc, args []*ast.Type, _ prog.IntTypeCommon) {
for i, arg := range args {
if desc.Args[i].Type.Kind == kindInt {
if arg.Ident != "" {
comp.addConst(infos, arg.Pos, arg.Ident)
}
for _, col := range arg.Colon {
if col.Ident != "" {
comp.addConst(infos, col.Pos, col.Ident)
}
}
}
}
})
}
func (comp *compiler) addConst(infos map[string]*constInfo, pos ast.Pos, name string) {
if _, builtin := comp.builtinConsts[name]; builtin {
return
}
info := getConstInfo(infos, pos)
info.consts[name] = true
}
type constInfo struct {
consts map[string]bool
defines map[string]string
includeArray []string
incdirArray []string
}
func getConstInfo(infos map[string]*constInfo, pos ast.Pos) *constInfo {
info := infos[pos.File]
if info == nil {
info = &constInfo{
consts: make(map[string]bool),
defines: make(map[string]string),
}
infos[pos.File] = info
}
return info
}
func convertConstInfo(infos map[string]*constInfo) map[string]*ConstInfo {
res := make(map[string]*ConstInfo)
for file, info := range infos {
if file == ast.BuiltinFile {
continue
}
res[file] = &ConstInfo{
File: file,
Consts: toArray(info.consts),
Includes: info.includeArray,
Incdirs: info.incdirArray,
Defines: info.defines,
}
}
return res
}
// assignSyscallNumbers assigns syscall numbers, discards unsupported syscalls.
func (comp *compiler) assignSyscallNumbers(consts map[string]uint64) {
for _, decl := range comp.desc.Nodes {
c, ok := decl.(*ast.Call)
if !ok || strings.HasPrefix(c.CallName, "syz_") {
continue
}
str := comp.target.SyscallPrefix + c.CallName
nr, ok := consts[str]
if ok {
c.NR = nr
continue
}
c.NR = ^uint64(0) // mark as unused to not generate it
name := "syscall " + c.CallName
if !comp.unsupported[name] {
comp.unsupported[name] = true
comp.warning(c.Pos, "unsupported syscall: %v due to missing const %v",
c.CallName, str)
}
}
}
// patchConsts replaces all symbolic consts with their numeric values taken from consts map.
// Updates desc and returns set of unsupported syscalls and flags.
func (comp *compiler) patchConsts(consts0 map[string]uint64) {
consts := make(map[string]uint64)
for name, val := range consts0 {
consts[name] = val
}
for name, val := range comp.builtinConsts {
if _, ok := consts[name]; ok {
panic(fmt.Sprintf("builtin const %v already defined", name))
}
consts[name] = val
}
for _, decl := range comp.desc.Nodes {
switch n := decl.(type) {
case *ast.IntFlags:
// Unsupported flag values are dropped.
var values []*ast.Int
for _, v := range n.Values {
if comp.patchIntConst(v, consts, nil) {
values = append(values, v)
}
}
n.Values = values
case *ast.Resource, *ast.Struct, *ast.Call, *ast.TypeDef:
// Walk whole tree and replace consts in Type's and Int's.
missing := ""
comp.foreachType(decl, func(_ *ast.Type, desc *typeDesc,
args []*ast.Type, _ prog.IntTypeCommon) {
for i, arg := range args {
if desc.Args[i].Type.Kind == kindInt {
comp.patchTypeConst(arg, consts, &missing)
}
}
})
switch n := decl.(type) {
case *ast.Resource:
for _, v := range n.Values {
comp.patchIntConst(v, consts, &missing)
}
case *ast.Call:
for _, attr := range n.Attrs {
if callAttrs[attr.Ident].HasArg {
comp.patchTypeConst(attr.Args[0], consts, &missing)
}
}
case *ast.Struct:
for _, attr := range n.Attrs {
if structOrUnionAttrs(n)[attr.Ident].HasArg {
comp.patchTypeConst(attr.Args[0], consts, &missing)
}
}
}
if missing == "" {
continue
}
// Produce a warning about unsupported syscall/resource/struct.
// TODO(dvyukov): we should transitively remove everything that
// depends on unsupported things. Potentially we still can get,
// say, a bad int range error due to the wrong const value.
// However, if we have a union where one of the options is
// arch-specific and does not have a const value, it's probably
// better to remove just that option. But then if we get to 0
// options in the union, we still need to remove it entirely.
pos, typ, name := decl.Info()
if id := typ + " " + name; !comp.unsupported[id] {
comp.unsupported[id] = true
comp.warning(pos, "unsupported %v: %v due to missing const %v",
typ, name, missing)
}
if c, ok := decl.(*ast.Call); ok {
c.NR = ^uint64(0) // mark as unused to not generate it
}
}
}
}
func (comp *compiler) patchIntConst(n *ast.Int, consts map[string]uint64, missing *string) bool {
return comp.patchConst(&n.Value, &n.Ident, consts, missing, false)
}
func (comp *compiler) patchTypeConst(n *ast.Type, consts map[string]uint64, missing *string) {
comp.patchConst(&n.Value, &n.Ident, consts, missing, true)
for _, col := range n.Colon {
comp.patchConst(&col.Value, &col.Ident, consts, missing, true)
}
}
func (comp *compiler) patchConst(val *uint64, id *string, consts map[string]uint64, missing *string, reset bool) bool {
if *id == "" {
return true
}
if v, ok := consts[*id]; ok {
if reset {
*id = ""
}
*val = v
return true
}
if missing != nil && *missing == "" {
*missing = *id
}
// 1 is slightly safer than 0 and allows to work-around e.g. an array size
// that comes from a const missing on an arch. Also see the TODO in patchConsts.
*val = 1
return false
}
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