Switch from glide to dep. Check in vendor/

vendor/golang.org/x/net/bpf/instructions.go

@@ -0,0 +1,704 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bpf
+
+import "fmt"
+
+// An Instruction is one instruction executed by the BPF virtual
+// machine.
+type Instruction interface {
+	// Assemble assembles the Instruction into a RawInstruction.
+	Assemble() (RawInstruction, error)
+}
+
+// A RawInstruction is a raw BPF virtual machine instruction.
+type RawInstruction struct {
+	// Operation to execute.
+	Op uint16
+	// For conditional jump instructions, the number of instructions
+	// to skip if the condition is true/false.
+	Jt uint8
+	Jf uint8
+	// Constant parameter. The meaning depends on the Op.
+	K uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (ri RawInstruction) Assemble() (RawInstruction, error) { return ri, nil }
+
+// Disassemble parses ri into an Instruction and returns it. If ri is
+// not recognized by this package, ri itself is returned.
+func (ri RawInstruction) Disassemble() Instruction {
+	switch ri.Op & opMaskCls {
+	case opClsLoadA, opClsLoadX:
+		reg := Register(ri.Op & opMaskLoadDest)
+		sz := 0
+		switch ri.Op & opMaskLoadWidth {
+		case opLoadWidth4:
+			sz = 4
+		case opLoadWidth2:
+			sz = 2
+		case opLoadWidth1:
+			sz = 1
+		default:
+			return ri
+		}
+		switch ri.Op & opMaskLoadMode {
+		case opAddrModeImmediate:
+			if sz != 4 {
+				return ri
+			}
+			return LoadConstant{Dst: reg, Val: ri.K}
+		case opAddrModeScratch:
+			if sz != 4 || ri.K > 15 {
+				return ri
+			}
+			return LoadScratch{Dst: reg, N: int(ri.K)}
+		case opAddrModeAbsolute:
+			if ri.K > extOffset+0xffffffff {
+				return LoadExtension{Num: Extension(-extOffset + ri.K)}
+			}
+			return LoadAbsolute{Size: sz, Off: ri.K}
+		case opAddrModeIndirect:
+			return LoadIndirect{Size: sz, Off: ri.K}
+		case opAddrModePacketLen:
+			if sz != 4 {
+				return ri
+			}
+			return LoadExtension{Num: ExtLen}
+		case opAddrModeMemShift:
+			return LoadMemShift{Off: ri.K}
+		default:
+			return ri
+		}
+
+	case opClsStoreA:
+		if ri.Op != opClsStoreA || ri.K > 15 {
+			return ri
+		}
+		return StoreScratch{Src: RegA, N: int(ri.K)}
+
+	case opClsStoreX:
+		if ri.Op != opClsStoreX || ri.K > 15 {
+			return ri
+		}
+		return StoreScratch{Src: RegX, N: int(ri.K)}
+
+	case opClsALU:
+		switch op := ALUOp(ri.Op & opMaskOperator); op {
+		case ALUOpAdd, ALUOpSub, ALUOpMul, ALUOpDiv, ALUOpOr, ALUOpAnd, ALUOpShiftLeft, ALUOpShiftRight, ALUOpMod, ALUOpXor:
+			if ri.Op&opMaskOperandSrc != 0 {
+				return ALUOpX{Op: op}
+			}
+			return ALUOpConstant{Op: op, Val: ri.K}
+		case aluOpNeg:
+			return NegateA{}
+		default:
+			return ri
+		}
+
+	case opClsJump:
+		if ri.Op&opMaskJumpConst != opClsJump {
+			return ri
+		}
+		switch ri.Op & opMaskJumpCond {
+		case opJumpAlways:
+			return Jump{Skip: ri.K}
+		case opJumpEqual:
+			if ri.Jt == 0 {
+				return JumpIf{
+					Cond:      JumpNotEqual,
+					Val:       ri.K,
+					SkipTrue:  ri.Jf,
+					SkipFalse: 0,
+				}
+			}
+			return JumpIf{
+				Cond:      JumpEqual,
+				Val:       ri.K,
+				SkipTrue:  ri.Jt,
+				SkipFalse: ri.Jf,
+			}
+		case opJumpGT:
+			if ri.Jt == 0 {
+				return JumpIf{
+					Cond:      JumpLessOrEqual,
+					Val:       ri.K,
+					SkipTrue:  ri.Jf,
+					SkipFalse: 0,
+				}
+			}
+			return JumpIf{
+				Cond:      JumpGreaterThan,
+				Val:       ri.K,
+				SkipTrue:  ri.Jt,
+				SkipFalse: ri.Jf,
+			}
+		case opJumpGE:
+			if ri.Jt == 0 {
+				return JumpIf{
+					Cond:      JumpLessThan,
+					Val:       ri.K,
+					SkipTrue:  ri.Jf,
+					SkipFalse: 0,
+				}
+			}
+			return JumpIf{
+				Cond:      JumpGreaterOrEqual,
+				Val:       ri.K,
+				SkipTrue:  ri.Jt,
+				SkipFalse: ri.Jf,
+			}
+		case opJumpSet:
+			return JumpIf{
+				Cond:      JumpBitsSet,
+				Val:       ri.K,
+				SkipTrue:  ri.Jt,
+				SkipFalse: ri.Jf,
+			}
+		default:
+			return ri
+		}
+
+	case opClsReturn:
+		switch ri.Op {
+		case opClsReturn | opRetSrcA:
+			return RetA{}
+		case opClsReturn | opRetSrcConstant:
+			return RetConstant{Val: ri.K}
+		default:
+			return ri
+		}
+
+	case opClsMisc:
+		switch ri.Op {
+		case opClsMisc | opMiscTAX:
+			return TAX{}
+		case opClsMisc | opMiscTXA:
+			return TXA{}
+		default:
+			return ri
+		}
+
+	default:
+		panic("unreachable") // switch is exhaustive on the bit pattern
+	}
+}
+
+// LoadConstant loads Val into register Dst.
+type LoadConstant struct {
+	Dst Register
+	Val uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadConstant) Assemble() (RawInstruction, error) {
+	return assembleLoad(a.Dst, 4, opAddrModeImmediate, a.Val)
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadConstant) String() string {
+	switch a.Dst {
+	case RegA:
+		return fmt.Sprintf("ld #%d", a.Val)
+	case RegX:
+		return fmt.Sprintf("ldx #%d", a.Val)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// LoadScratch loads scratch[N] into register Dst.
+type LoadScratch struct {
+	Dst Register
+	N   int // 0-15
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadScratch) Assemble() (RawInstruction, error) {
+	if a.N < 0 || a.N > 15 {
+		return RawInstruction{}, fmt.Errorf("invalid scratch slot %d", a.N)
+	}
+	return assembleLoad(a.Dst, 4, opAddrModeScratch, uint32(a.N))
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadScratch) String() string {
+	switch a.Dst {
+	case RegA:
+		return fmt.Sprintf("ld M[%d]", a.N)
+	case RegX:
+		return fmt.Sprintf("ldx M[%d]", a.N)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// LoadAbsolute loads packet[Off:Off+Size] as an integer value into
+// register A.
+type LoadAbsolute struct {
+	Off  uint32
+	Size int // 1, 2 or 4
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadAbsolute) Assemble() (RawInstruction, error) {
+	return assembleLoad(RegA, a.Size, opAddrModeAbsolute, a.Off)
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadAbsolute) String() string {
+	switch a.Size {
+	case 1: // byte
+		return fmt.Sprintf("ldb [%d]", a.Off)
+	case 2: // half word
+		return fmt.Sprintf("ldh [%d]", a.Off)
+	case 4: // word
+		if a.Off > extOffset+0xffffffff {
+			return LoadExtension{Num: Extension(a.Off + 0x1000)}.String()
+		}
+		return fmt.Sprintf("ld [%d]", a.Off)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// LoadIndirect loads packet[X+Off:X+Off+Size] as an integer value
+// into register A.
+type LoadIndirect struct {
+	Off  uint32
+	Size int // 1, 2 or 4
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadIndirect) Assemble() (RawInstruction, error) {
+	return assembleLoad(RegA, a.Size, opAddrModeIndirect, a.Off)
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadIndirect) String() string {
+	switch a.Size {
+	case 1: // byte
+		return fmt.Sprintf("ldb [x + %d]", a.Off)
+	case 2: // half word
+		return fmt.Sprintf("ldh [x + %d]", a.Off)
+	case 4: // word
+		return fmt.Sprintf("ld [x + %d]", a.Off)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// LoadMemShift multiplies the first 4 bits of the byte at packet[Off]
+// by 4 and stores the result in register X.
+//
+// This instruction is mainly useful to load into X the length of an
+// IPv4 packet header in a single instruction, rather than have to do
+// the arithmetic on the header's first byte by hand.
+type LoadMemShift struct {
+	Off uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadMemShift) Assemble() (RawInstruction, error) {
+	return assembleLoad(RegX, 1, opAddrModeMemShift, a.Off)
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadMemShift) String() string {
+	return fmt.Sprintf("ldx 4*([%d]&0xf)", a.Off)
+}
+
+// LoadExtension invokes a linux-specific extension and stores the
+// result in register A.
+type LoadExtension struct {
+	Num Extension
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a LoadExtension) Assemble() (RawInstruction, error) {
+	if a.Num == ExtLen {
+		return assembleLoad(RegA, 4, opAddrModePacketLen, 0)
+	}
+	return assembleLoad(RegA, 4, opAddrModeAbsolute, uint32(extOffset+a.Num))
+}
+
+// String returns the the instruction in assembler notation.
+func (a LoadExtension) String() string {
+	switch a.Num {
+	case ExtLen:
+		return "ld #len"
+	case ExtProto:
+		return "ld #proto"
+	case ExtType:
+		return "ld #type"
+	case ExtPayloadOffset:
+		return "ld #poff"
+	case ExtInterfaceIndex:
+		return "ld #ifidx"
+	case ExtNetlinkAttr:
+		return "ld #nla"
+	case ExtNetlinkAttrNested:
+		return "ld #nlan"
+	case ExtMark:
+		return "ld #mark"
+	case ExtQueue:
+		return "ld #queue"
+	case ExtLinkLayerType:
+		return "ld #hatype"
+	case ExtRXHash:
+		return "ld #rxhash"
+	case ExtCPUID:
+		return "ld #cpu"
+	case ExtVLANTag:
+		return "ld #vlan_tci"
+	case ExtVLANTagPresent:
+		return "ld #vlan_avail"
+	case ExtVLANProto:
+		return "ld #vlan_tpid"
+	case ExtRand:
+		return "ld #rand"
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// StoreScratch stores register Src into scratch[N].
+type StoreScratch struct {
+	Src Register
+	N   int // 0-15
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a StoreScratch) Assemble() (RawInstruction, error) {
+	if a.N < 0 || a.N > 15 {
+		return RawInstruction{}, fmt.Errorf("invalid scratch slot %d", a.N)
+	}
+	var op uint16
+	switch a.Src {
+	case RegA:
+		op = opClsStoreA
+	case RegX:
+		op = opClsStoreX
+	default:
+		return RawInstruction{}, fmt.Errorf("invalid source register %v", a.Src)
+	}
+
+	return RawInstruction{
+		Op: op,
+		K:  uint32(a.N),
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a StoreScratch) String() string {
+	switch a.Src {
+	case RegA:
+		return fmt.Sprintf("st M[%d]", a.N)
+	case RegX:
+		return fmt.Sprintf("stx M[%d]", a.N)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// ALUOpConstant executes A = A <Op> Val.
+type ALUOpConstant struct {
+	Op  ALUOp
+	Val uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a ALUOpConstant) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsALU | opALUSrcConstant | uint16(a.Op),
+		K:  a.Val,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a ALUOpConstant) String() string {
+	switch a.Op {
+	case ALUOpAdd:
+		return fmt.Sprintf("add #%d", a.Val)
+	case ALUOpSub:
+		return fmt.Sprintf("sub #%d", a.Val)
+	case ALUOpMul:
+		return fmt.Sprintf("mul #%d", a.Val)
+	case ALUOpDiv:
+		return fmt.Sprintf("div #%d", a.Val)
+	case ALUOpMod:
+		return fmt.Sprintf("mod #%d", a.Val)
+	case ALUOpAnd:
+		return fmt.Sprintf("and #%d", a.Val)
+	case ALUOpOr:
+		return fmt.Sprintf("or #%d", a.Val)
+	case ALUOpXor:
+		return fmt.Sprintf("xor #%d", a.Val)
+	case ALUOpShiftLeft:
+		return fmt.Sprintf("lsh #%d", a.Val)
+	case ALUOpShiftRight:
+		return fmt.Sprintf("rsh #%d", a.Val)
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// ALUOpX executes A = A <Op> X
+type ALUOpX struct {
+	Op ALUOp
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a ALUOpX) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsALU | opALUSrcX | uint16(a.Op),
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a ALUOpX) String() string {
+	switch a.Op {
+	case ALUOpAdd:
+		return "add x"
+	case ALUOpSub:
+		return "sub x"
+	case ALUOpMul:
+		return "mul x"
+	case ALUOpDiv:
+		return "div x"
+	case ALUOpMod:
+		return "mod x"
+	case ALUOpAnd:
+		return "and x"
+	case ALUOpOr:
+		return "or x"
+	case ALUOpXor:
+		return "xor x"
+	case ALUOpShiftLeft:
+		return "lsh x"
+	case ALUOpShiftRight:
+		return "rsh x"
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+// NegateA executes A = -A.
+type NegateA struct{}
+
+// Assemble implements the Instruction Assemble method.
+func (a NegateA) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsALU | uint16(aluOpNeg),
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a NegateA) String() string {
+	return fmt.Sprintf("neg")
+}
+
+// Jump skips the following Skip instructions in the program.
+type Jump struct {
+	Skip uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a Jump) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsJump | opJumpAlways,
+		K:  a.Skip,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a Jump) String() string {
+	return fmt.Sprintf("ja %d", a.Skip)
+}
+
+// JumpIf skips the following Skip instructions in the program if A
+// <Cond> Val is true.
+type JumpIf struct {
+	Cond      JumpTest
+	Val       uint32
+	SkipTrue  uint8
+	SkipFalse uint8
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a JumpIf) Assemble() (RawInstruction, error) {
+	var (
+		cond uint16
+		flip bool
+	)
+	switch a.Cond {
+	case JumpEqual:
+		cond = opJumpEqual
+	case JumpNotEqual:
+		cond, flip = opJumpEqual, true
+	case JumpGreaterThan:
+		cond = opJumpGT
+	case JumpLessThan:
+		cond, flip = opJumpGE, true
+	case JumpGreaterOrEqual:
+		cond = opJumpGE
+	case JumpLessOrEqual:
+		cond, flip = opJumpGT, true
+	case JumpBitsSet:
+		cond = opJumpSet
+	case JumpBitsNotSet:
+		cond, flip = opJumpSet, true
+	default:
+		return RawInstruction{}, fmt.Errorf("unknown JumpTest %v", a.Cond)
+	}
+	jt, jf := a.SkipTrue, a.SkipFalse
+	if flip {
+		jt, jf = jf, jt
+	}
+	return RawInstruction{
+		Op: opClsJump | cond,
+		Jt: jt,
+		Jf: jf,
+		K:  a.Val,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a JumpIf) String() string {
+	switch a.Cond {
+	// K == A
+	case JumpEqual:
+		return conditionalJump(a, "jeq", "jneq")
+	// K != A
+	case JumpNotEqual:
+		return fmt.Sprintf("jneq #%d,%d", a.Val, a.SkipTrue)
+	// K > A
+	case JumpGreaterThan:
+		return conditionalJump(a, "jgt", "jle")
+	// K < A
+	case JumpLessThan:
+		return fmt.Sprintf("jlt #%d,%d", a.Val, a.SkipTrue)
+	// K >= A
+	case JumpGreaterOrEqual:
+		return conditionalJump(a, "jge", "jlt")
+	// K <= A
+	case JumpLessOrEqual:
+		return fmt.Sprintf("jle #%d,%d", a.Val, a.SkipTrue)
+	// K & A != 0
+	case JumpBitsSet:
+		if a.SkipFalse > 0 {
+			return fmt.Sprintf("jset #%d,%d,%d", a.Val, a.SkipTrue, a.SkipFalse)
+		}
+		return fmt.Sprintf("jset #%d,%d", a.Val, a.SkipTrue)
+	// K & A == 0, there is no assembler instruction for JumpBitNotSet, use JumpBitSet and invert skips
+	case JumpBitsNotSet:
+		return JumpIf{Cond: JumpBitsSet, SkipTrue: a.SkipFalse, SkipFalse: a.SkipTrue, Val: a.Val}.String()
+	default:
+		return fmt.Sprintf("unknown instruction: %#v", a)
+	}
+}
+
+func conditionalJump(inst JumpIf, positiveJump, negativeJump string) string {
+	if inst.SkipTrue > 0 {
+		if inst.SkipFalse > 0 {
+			return fmt.Sprintf("%s #%d,%d,%d", positiveJump, inst.Val, inst.SkipTrue, inst.SkipFalse)
+		}
+		return fmt.Sprintf("%s #%d,%d", positiveJump, inst.Val, inst.SkipTrue)
+	}
+	return fmt.Sprintf("%s #%d,%d", negativeJump, inst.Val, inst.SkipFalse)
+}
+
+// RetA exits the BPF program, returning the value of register A.
+type RetA struct{}
+
+// Assemble implements the Instruction Assemble method.
+func (a RetA) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsReturn | opRetSrcA,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a RetA) String() string {
+	return fmt.Sprintf("ret a")
+}
+
+// RetConstant exits the BPF program, returning a constant value.
+type RetConstant struct {
+	Val uint32
+}
+
+// Assemble implements the Instruction Assemble method.
+func (a RetConstant) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsReturn | opRetSrcConstant,
+		K:  a.Val,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a RetConstant) String() string {
+	return fmt.Sprintf("ret #%d", a.Val)
+}
+
+// TXA copies the value of register X to register A.
+type TXA struct{}
+
+// Assemble implements the Instruction Assemble method.
+func (a TXA) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsMisc | opMiscTXA,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a TXA) String() string {
+	return fmt.Sprintf("txa")
+}
+
+// TAX copies the value of register A to register X.
+type TAX struct{}
+
+// Assemble implements the Instruction Assemble method.
+func (a TAX) Assemble() (RawInstruction, error) {
+	return RawInstruction{
+		Op: opClsMisc | opMiscTAX,
+	}, nil
+}
+
+// String returns the the instruction in assembler notation.
+func (a TAX) String() string {
+	return fmt.Sprintf("tax")
+}
+
+func assembleLoad(dst Register, loadSize int, mode uint16, k uint32) (RawInstruction, error) {
+	var (
+		cls uint16
+		sz  uint16
+	)
+	switch dst {
+	case RegA:
+		cls = opClsLoadA
+	case RegX:
+		cls = opClsLoadX
+	default:
+		return RawInstruction{}, fmt.Errorf("invalid target register %v", dst)
+	}
+	switch loadSize {
+	case 1:
+		sz = opLoadWidth1
+	case 2:
+		sz = opLoadWidth2
+	case 4:
+		sz = opLoadWidth4
+	default:
+		return RawInstruction{}, fmt.Errorf("invalid load byte length %d", sz)
+	}
+	return RawInstruction{
+		Op: cls | sz | mode,
+		K:  k,
+	}, nil
+}