Bump dependency opencontainers/runc@v1.0.0-rc10

vendor/github.com/cilium/ebpf/asm/opcode.go

@@ -0,0 +1,237 @@
+package asm
+
+import (
+	"fmt"
+	"strings"
+)
+
+//go:generate stringer -output opcode_string.go -type=Class
+
+type encoding int
+
+const (
+	unknownEncoding encoding = iota
+	loadOrStore
+	jumpOrALU
+)
+
+// Class of operations
+//
+//    msb      lsb
+//    +---+--+---+
+//    |  ??  |CLS|
+//    +---+--+---+
+type Class uint8
+
+const classMask OpCode = 0x07
+
+const (
+	// LdClass load memory
+	LdClass Class = 0x00
+	// LdXClass load memory from constant
+	LdXClass Class = 0x01
+	// StClass load register from memory
+	StClass Class = 0x02
+	// StXClass load register from constant
+	StXClass Class = 0x03
+	// ALUClass arithmetic operators
+	ALUClass Class = 0x04
+	// JumpClass jump operators
+	JumpClass Class = 0x05
+	// ALU64Class arithmetic in 64 bit mode
+	ALU64Class Class = 0x07
+)
+
+func (cls Class) encoding() encoding {
+	switch cls {
+	case LdClass, LdXClass, StClass, StXClass:
+		return loadOrStore
+	case ALU64Class, ALUClass, JumpClass:
+		return jumpOrALU
+	default:
+		return unknownEncoding
+	}
+}
+
+// OpCode is a packed eBPF opcode.
+//
+// Its encoding is defined by a Class value:
+//
+//    msb      lsb
+//    +----+-+---+
+//    | ???? |CLS|
+//    +----+-+---+
+type OpCode uint8
+
+// InvalidOpCode is returned by setters on OpCode
+const InvalidOpCode OpCode = 0xff
+
+// marshalledInstructions returns the number of BPF instructions required
+// to encode this opcode.
+func (op OpCode) marshalledInstructions() int {
+	if op == LoadImmOp(DWord) {
+		return 2
+	}
+	return 1
+}
+
+func (op OpCode) isDWordLoad() bool {
+	return op == LoadImmOp(DWord)
+}
+
+// Class returns the class of operation.
+func (op OpCode) Class() Class {
+	return Class(op & classMask)
+}
+
+// Mode returns the mode for load and store operations.
+func (op OpCode) Mode() Mode {
+	if op.Class().encoding() != loadOrStore {
+		return InvalidMode
+	}
+	return Mode(op & modeMask)
+}
+
+// Size returns the size for load and store operations.
+func (op OpCode) Size() Size {
+	if op.Class().encoding() != loadOrStore {
+		return InvalidSize
+	}
+	return Size(op & sizeMask)
+}
+
+// Source returns the source for branch and ALU operations.
+func (op OpCode) Source() Source {
+	if op.Class().encoding() != jumpOrALU || op.ALUOp() == Swap {
+		return InvalidSource
+	}
+	return Source(op & sourceMask)
+}
+
+// ALUOp returns the ALUOp.
+func (op OpCode) ALUOp() ALUOp {
+	if op.Class().encoding() != jumpOrALU {
+		return InvalidALUOp
+	}
+	return ALUOp(op & aluMask)
+}
+
+// Endianness returns the Endianness for a byte swap instruction.
+func (op OpCode) Endianness() Endianness {
+	if op.ALUOp() != Swap {
+		return InvalidEndian
+	}
+	return Endianness(op & endianMask)
+}
+
+// JumpOp returns the JumpOp.
+func (op OpCode) JumpOp() JumpOp {
+	if op.Class().encoding() != jumpOrALU {
+		return InvalidJumpOp
+	}
+	return JumpOp(op & jumpMask)
+}
+
+// SetMode sets the mode on load and store operations.
+//
+// Returns InvalidOpCode if op is of the wrong class.
+func (op OpCode) SetMode(mode Mode) OpCode {
+	if op.Class().encoding() != loadOrStore || !valid(OpCode(mode), modeMask) {
+		return InvalidOpCode
+	}
+	return (op & ^modeMask) | OpCode(mode)
+}
+
+// SetSize sets the size on load and store operations.
+//
+// Returns InvalidOpCode if op is of the wrong class.
+func (op OpCode) SetSize(size Size) OpCode {
+	if op.Class().encoding() != loadOrStore || !valid(OpCode(size), sizeMask) {
+		return InvalidOpCode
+	}
+	return (op & ^sizeMask) | OpCode(size)
+}
+
+// SetSource sets the source on jump and ALU operations.
+//
+// Returns InvalidOpCode if op is of the wrong class.
+func (op OpCode) SetSource(source Source) OpCode {
+	if op.Class().encoding() != jumpOrALU || !valid(OpCode(source), sourceMask) {
+		return InvalidOpCode
+	}
+	return (op & ^sourceMask) | OpCode(source)
+}
+
+// SetALUOp sets the ALUOp on ALU operations.
+//
+// Returns InvalidOpCode if op is of the wrong class.
+func (op OpCode) SetALUOp(alu ALUOp) OpCode {
+	class := op.Class()
+	if (class != ALUClass && class != ALU64Class) || !valid(OpCode(alu), aluMask) {
+		return InvalidOpCode
+	}
+	return (op & ^aluMask) | OpCode(alu)
+}
+
+// SetJumpOp sets the JumpOp on jump operations.
+//
+// Returns InvalidOpCode if op is of the wrong class.
+func (op OpCode) SetJumpOp(jump JumpOp) OpCode {
+	if op.Class() != JumpClass || !valid(OpCode(jump), jumpMask) {
+		return InvalidOpCode
+	}
+	return (op & ^jumpMask) | OpCode(jump)
+}
+
+func (op OpCode) String() string {
+	var f strings.Builder
+
+	switch class := op.Class(); class {
+	case LdClass, LdXClass, StClass, StXClass:
+		f.WriteString(strings.TrimSuffix(class.String(), "Class"))
+
+		mode := op.Mode()
+		f.WriteString(strings.TrimSuffix(mode.String(), "Mode"))
+
+		switch op.Size() {
+		case DWord:
+			f.WriteString("DW")
+		case Word:
+			f.WriteString("W")
+		case Half:
+			f.WriteString("H")
+		case Byte:
+			f.WriteString("B")
+		}
+
+	case ALU64Class, ALUClass:
+		f.WriteString(op.ALUOp().String())
+
+		if op.ALUOp() == Swap {
+			// Width for Endian is controlled by Constant
+			f.WriteString(op.Endianness().String())
+		} else {
+			if class == ALUClass {
+				f.WriteString("32")
+			}
+
+			f.WriteString(strings.TrimSuffix(op.Source().String(), "Source"))
+		}
+
+	case JumpClass:
+		f.WriteString(op.JumpOp().String())
+		if jop := op.JumpOp(); jop != Exit && jop != Call {
+			f.WriteString(strings.TrimSuffix(op.Source().String(), "Source"))
+		}
+
+	default:
+		fmt.Fprintf(&f, "%#x", op)
+	}
+
+	return f.String()
+}
+
+// valid returns true if all bits in value are covered by mask.
+func valid(value, mask OpCode) bool {
+	return value & ^mask == 0
+}