99 lines
2.6 KiB
Go
99 lines
2.6 KiB
Go
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// Copyright 2024 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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// eofCodeBitmap collects data locations in code.
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func eofCodeBitmap(code []byte) bitvec {
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// The bitmap is 4 bytes longer than necessary, in case the code
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// ends with a PUSH32, the algorithm will push zeroes onto the
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// bitvector outside the bounds of the actual code.
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bits := make(bitvec, len(code)/8+1+4)
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return eofCodeBitmapInternal(code, bits)
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}
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// eofCodeBitmapInternal is the internal implementation of codeBitmap for EOF
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// code validation.
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func eofCodeBitmapInternal(code, bits bitvec) bitvec {
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for pc := uint64(0); pc < uint64(len(code)); {
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var (
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op = OpCode(code[pc])
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numbits uint16
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)
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pc++
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if op == RJUMPV {
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// RJUMPV is unique as it has a variable sized operand.
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// The total size is determined by the count byte which
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// immediate follows RJUMPV. Truncation will be caught
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// in other validation steps -- for now, just return a
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// valid bitmap for as much of the code as is
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// available.
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end := uint64(len(code))
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if pc >= end {
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// Count missing, no more bits to mark.
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return bits
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}
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numbits = uint16(code[pc])*2 + 3
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if pc+uint64(numbits) > end {
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// Jump table is truncated, mark as many bits
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// as possible.
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numbits = uint16(end - pc)
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}
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} else {
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numbits = uint16(Immediates(op))
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if numbits == 0 {
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continue
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}
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}
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if numbits >= 8 {
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for ; numbits >= 16; numbits -= 16 {
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bits.set16(pc)
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pc += 16
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}
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for ; numbits >= 8; numbits -= 8 {
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bits.set8(pc)
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pc += 8
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}
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}
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switch numbits {
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case 1:
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bits.set1(pc)
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pc += 1
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case 2:
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bits.setN(set2BitsMask, pc)
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pc += 2
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case 3:
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bits.setN(set3BitsMask, pc)
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pc += 3
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case 4:
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bits.setN(set4BitsMask, pc)
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pc += 4
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case 5:
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bits.setN(set5BitsMask, pc)
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pc += 5
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case 6:
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bits.setN(set6BitsMask, pc)
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pc += 6
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case 7:
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bits.setN(set7BitsMask, pc)
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pc += 7
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}
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}
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return bits
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}
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