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Diffstat (limited to 'vendor/golang.org/x/net/bpf/vm_instructions.go')
-rw-r--r--vendor/golang.org/x/net/bpf/vm_instructions.go174
1 files changed, 174 insertions, 0 deletions
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
+}