diff options
Diffstat (limited to 'vendor/github.com/cilium/ebpf/asm/opcode.go')
| -rw-r--r-- | vendor/github.com/cilium/ebpf/asm/opcode.go | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/vendor/github.com/cilium/ebpf/asm/opcode.go b/vendor/github.com/cilium/ebpf/asm/opcode.go new file mode 100644 index 000000000..dc4564a98 --- /dev/null +++ b/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 + +// rawInstructions returns the number of BPF instructions required +// to encode this opcode. +func (op OpCode) rawInstructions() int { + if op.isDWordLoad() { + 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, "OpCode(%#x)", uint8(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 +} |