From e1e8d058a33f7566f9c565d04b0d8b56f9645c35 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Wed, 25 Apr 2018 09:28:54 +0200 Subject: add vendor --- vendor/golang.org/x/net/bpf/vm_instructions.go | 174 +++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 vendor/golang.org/x/net/bpf/vm_instructions.go (limited to 'vendor/golang.org/x/net/bpf/vm_instructions.go') diff --git a/vendor/golang.org/x/net/bpf/vm_instructions.go b/vendor/golang.org/x/net/bpf/vm_instructions.go new file mode 100644 index 0000000..516f946 --- /dev/null +++ b/vendor/golang.org/x/net/bpf/vm_instructions.go @@ -0,0 +1,174 @@ +// 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 ( + "encoding/binary" + "fmt" +) + +func aluOpConstant(ins ALUOpConstant, regA uint32) uint32 { + return aluOpCommon(ins.Op, regA, ins.Val) +} + +func aluOpX(ins ALUOpX, regA uint32, regX uint32) (uint32, bool) { + // Guard against division or modulus by zero by terminating + // the program, as the OS BPF VM does + if regX == 0 { + switch ins.Op { + case ALUOpDiv, ALUOpMod: + return 0, false + } + } + + return aluOpCommon(ins.Op, regA, regX), true +} + +func aluOpCommon(op ALUOp, regA uint32, value uint32) uint32 { + switch op { + case ALUOpAdd: + return regA + value + case ALUOpSub: + return regA - value + case ALUOpMul: + return regA * value + case ALUOpDiv: + // Division by zero not permitted by NewVM and aluOpX checks + return regA / value + case ALUOpOr: + return regA | value + case ALUOpAnd: + return regA & value + case ALUOpShiftLeft: + return regA << value + case ALUOpShiftRight: + return regA >> value + case ALUOpMod: + // Modulus by zero not permitted by NewVM and aluOpX checks + return regA % value + case ALUOpXor: + return regA ^ value + default: + return regA + } +} + +func jumpIf(ins JumpIf, value uint32) int { + var ok bool + inV := uint32(ins.Val) + + switch ins.Cond { + case JumpEqual: + ok = value == inV + case JumpNotEqual: + ok = value != inV + case JumpGreaterThan: + ok = value > inV + case JumpLessThan: + ok = value < inV + case JumpGreaterOrEqual: + ok = value >= inV + case JumpLessOrEqual: + ok = value <= inV + case JumpBitsSet: + ok = (value & inV) != 0 + case JumpBitsNotSet: + ok = (value & inV) == 0 + } + + if ok { + return int(ins.SkipTrue) + } + + return int(ins.SkipFalse) +} + +func loadAbsolute(ins LoadAbsolute, in []byte) (uint32, bool) { + offset := int(ins.Off) + size := int(ins.Size) + + return loadCommon(in, offset, size) +} + +func loadConstant(ins LoadConstant, regA uint32, regX uint32) (uint32, uint32) { + switch ins.Dst { + case RegA: + regA = ins.Val + case RegX: + regX = ins.Val + } + + return regA, regX +} + +func loadExtension(ins LoadExtension, in []byte) uint32 { + switch ins.Num { + case ExtLen: + return uint32(len(in)) + default: + panic(fmt.Sprintf("unimplemented extension: %d", ins.Num)) + } +} + +func loadIndirect(ins LoadIndirect, in []byte, regX uint32) (uint32, bool) { + offset := int(ins.Off) + int(regX) + size := int(ins.Size) + + return loadCommon(in, offset, size) +} + +func loadMemShift(ins LoadMemShift, in []byte) (uint32, bool) { + offset := int(ins.Off) + + if !inBounds(len(in), offset, 0) { + return 0, false + } + + // Mask off high 4 bits and multiply low 4 bits by 4 + return uint32(in[offset]&0x0f) * 4, true +} + +func inBounds(inLen int, offset int, size int) bool { + return offset+size <= inLen +} + +func loadCommon(in []byte, offset int, size int) (uint32, bool) { + if !inBounds(len(in), offset, size) { + return 0, false + } + + switch size { + case 1: + return uint32(in[offset]), true + case 2: + return uint32(binary.BigEndian.Uint16(in[offset : offset+size])), true + case 4: + return uint32(binary.BigEndian.Uint32(in[offset : offset+size])), true + default: + panic(fmt.Sprintf("invalid load size: %d", size)) + } +} + +func loadScratch(ins LoadScratch, regScratch [16]uint32, regA uint32, regX uint32) (uint32, uint32) { + switch ins.Dst { + case RegA: + regA = regScratch[ins.N] + case RegX: + regX = regScratch[ins.N] + } + + return regA, regX +} + +func storeScratch(ins StoreScratch, regScratch [16]uint32, regA uint32, regX uint32) [16]uint32 { + switch ins.Src { + case RegA: + regScratch[ins.N] = regA + case RegX: + regScratch[ins.N] = regX + } + + return regScratch +} -- cgit v1.2.3