syzkaller/prog/size.go
Andrey Konovalov cfc46d9d0b prog: split Arg into smaller structs
Right now Arg is a huge struct (160 bytes), which has many different fields
used for different arg kinds. Since most of the args we see in a typical
corpus are ArgConst, this results in a significant memory overuse.

This change:
- makes Arg an interface instead of a struct
- adds a SomethingArg struct for each arg kind we have
- converts all *Arg pointers into just Arg, since interface variable by
  itself contains a pointer to the actual data
- removes ArgPageSize, now ConstArg is used instead
- consolidates correspondence between arg kinds and types, see comments
  before each SomethingArg struct definition
- now LenType args that denote the length of VmaType args are serialized as
  "0x1000" instead of "(0x1000)"; to preserve backwards compatibility
  syzkaller is able to parse the old format for now
- multiple small changes all over to make the above work

After this change syzkaller uses twice less memory after deserializing a
typical corpus.
2017-07-17 14:34:09 +02:00

111 lines
2.6 KiB
Go

// 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 prog
import (
"fmt"
"github.com/google/syzkaller/sys"
)
func generateSize(arg Arg, lenType *sys.LenType) Arg {
if arg == nil {
// Arg is an optional pointer, set size to 0.
return constArg(lenType, 0)
}
switch arg.Type().(type) {
case *sys.VmaType:
a := arg.(*PointerArg)
return constArg(lenType, a.PagesNum*pageSize)
case *sys.ArrayType:
a := arg.(*GroupArg)
if lenType.ByteSize != 0 {
return constArg(lenType, a.Size()/lenType.ByteSize)
} else {
return constArg(lenType, uintptr(len(a.Inner)))
}
default:
if lenType.ByteSize != 0 {
return constArg(lenType, arg.Size()/lenType.ByteSize)
} else {
return constArg(lenType, arg.Size())
}
}
}
func assignSizes(args []Arg, parentsMap map[Arg]Arg) {
// Create a map from field names to args.
argsMap := make(map[string]Arg)
for _, arg := range args {
if sys.IsPad(arg.Type()) {
continue
}
argsMap[arg.Type().FieldName()] = arg
}
// Fill in size arguments.
for _, arg := range args {
if arg = InnerArg(arg); arg == nil {
continue // Pointer to optional len field, no need to fill in value.
}
if typ, ok := arg.Type().(*sys.LenType); ok {
a := arg.(*ConstArg)
buf, ok := argsMap[typ.Buf]
if ok {
*a = *generateSize(InnerArg(buf), typ).(*ConstArg)
continue
}
if typ.Buf == "parent" {
a.Val = parentsMap[arg].Size()
if typ.ByteSize != 0 {
a.Val /= typ.ByteSize
}
continue
}
sizeAssigned := false
for parent := parentsMap[arg]; parent != nil; parent = parentsMap[parent] {
if typ.Buf == parent.Type().Name() {
a.Val = parent.Size()
if typ.ByteSize != 0 {
a.Val /= typ.ByteSize
}
sizeAssigned = true
break
}
}
if sizeAssigned {
continue
}
panic(fmt.Sprintf("len field '%v' references non existent field '%v', argsMap: %+v",
typ.FieldName(), typ.Buf, argsMap))
}
}
}
func assignSizesArray(args []Arg) {
parentsMap := make(map[Arg]Arg)
foreachArgArray(&args, nil, func(arg, base Arg, _ *[]Arg) {
if _, ok := arg.Type().(*sys.StructType); ok {
for _, field := range arg.(*GroupArg).Inner {
parentsMap[InnerArg(field)] = arg
}
}
})
assignSizes(args, parentsMap)
foreachArgArray(&args, nil, func(arg, base Arg, _ *[]Arg) {
if _, ok := arg.Type().(*sys.StructType); ok {
assignSizes(arg.(*GroupArg).Inner, parentsMap)
}
})
}
func assignSizesCall(c *Call) {
assignSizesArray(c.Args)
}