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evm.dfy
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/*
* Copyright 2022 ConsenSys Software Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License. You may obtain
* a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software dis-
* tributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
include "../../libs/DafnyCrypto/src/dafny/util/option.dfy"
include "bytecode.dfy"
include "core/fork.dfy"
include "state.dfy"
include "opcodes.dfy"
include "gas.dfy"
/**
* Top-level definition of an Ethereum Virtual Machine.
*/
module EVM {
import opened EvmState
import opened Gas
import opened Int
import opened EvmFork
import opened Opcode
import opened Optional
import Bytecode
/** An empty VM, with some initial gas and initial stack.
*
* @param gas The gas loaded in this EVM.
* @returns An ready-to-use EVM.
*/
function Init(gas: nat, fork : Fork := BERLIN, stk: seq<u256> := [], code: seq<u8> := []) : (st:ExecutingState)
requires |code| <= Code.MAX_CODE_SIZE
requires |stk| <= 1024
{
var tx := Context.Create(0,0,0,0,[],true,0,Context.Block.Info(0,0,0,0,0,0,0));
Create(fork, tx, map[0:=WorldState.DefaultAccount()], gas, code, Precompiled.DEFAULT, stk)
}
/**
* Create a fresh EVM to execute a given sequence of bytecode instructions.
* The EVM is initialised with an empty stack and empty local memory.
*/
function Create(fork: Fork, context: Context.T, world: map<u160,WorldState.Account>, gas: nat, code: seq<u8>, precompiled: Precompiled.T := Precompiled.DEFAULT, st: seq<u256> := []) : ExecutingState
// Code to executed cannot exceed maximum limit.
requires |code| <= Code.MAX_CODE_SIZE
requires |st| <= Stack.CAPACITY
// Account under which EVM is executing must exist!
requires context.address in world {
var stck := Stack.Make(st);
var mem := Memory.Create();
var tstore := TransientStorage.Create();
var wld := WorldState.Create(world);
var cod := Code.Create(code);
var sub := SubState.Create();
var evm := EVM(fork,stack:=stck,memory:=mem,transient:=tstore,world:=wld,context:=context,precompiled:=precompiled,code:=cod,substate:=sub,gas:=gas,pc:=0);
// Off we go!
EXECUTING(evm)
}
/**
* Execute the next bytecode as determined by the current machine's state.
* This requires decoding the bytecode at the current PC location.
*/
function Execute(st: ExecutingState): State {
// Read opcode byte from memory. If the read is out-of-bounds, then
// STOP is returned by default.
var opcode := Code.DecodeUint8(st.evm.code,st.evm.pc as nat);
// Check fork supports given bytecode
if st.evm.fork.IsBytecode(opcode)
then
// Deduct gas for the given bytecode.
match DeductGas(opcode,st)
// Not out of gas
case EXECUTING(vm) => ExecuteBytecode(opcode,EXECUTING(vm))
// Out of gas (or invalid opcode)
case s => s
else
ERROR(INVALID_OPCODE)
}
/**
* Execute the next instruction
* return
* @note If the opcode semantics/gas is not implemented, the next
* state is INVALID.
*/
function {:tailrecursion true} ExecuteN(st:ExecutingState, steps: nat := 1): State
decreases steps
requires steps > 0
{
// Execute next instruction
var nst := Execute(st);
// Recurse as necessary
if steps == 1 || !nst.EXECUTING? then nst else ExecuteN(nst,steps-1)
}
/**
* Deduct gas for the given opcode from the executing state. This may or
* may not result in an executing state. For example, if the executing
* state does not have enough gas.
*/
function DeductGas(op: u8, s: ExecutingState): State
{
match op
case STOP => s.UseGas(G_ZERO)
case ADD => s.UseGas(G_VERYLOW)
case MUL => s.UseGas(G_LOW)
case SUB => s.UseGas(G_VERYLOW)
case DIV => s.UseGas(G_LOW)
case SDIV => s.UseGas(G_LOW)
case MOD => s.UseGas(G_LOW)
case SMOD => s.UseGas(G_LOW)
case ADDMOD => s.UseGas(G_MID)
case MULMOD => s.UseGas(G_MID)
case EXP => s.UseGas(CostExp(s))
case SIGNEXTEND => s.UseGas(G_LOW)
// 0x10s: Comparison & Bitwise Logic
case LT => s.UseGas(G_VERYLOW)
case GT => s.UseGas(G_VERYLOW)
case SLT => s.UseGas(G_VERYLOW)
case SGT => s.UseGas(G_VERYLOW)
case EQ => s.UseGas(G_VERYLOW)
case ISZERO => s.UseGas(G_VERYLOW)
case AND => s.UseGas(G_VERYLOW)
case OR => s.UseGas(G_VERYLOW)
case XOR => s.UseGas(G_VERYLOW)
case NOT => s.UseGas(G_VERYLOW)
case BYTE => s.UseGas(G_VERYLOW)
case SHL => s.UseGas(G_VERYLOW)
case SHR => s.UseGas(G_VERYLOW)
case SAR => s.UseGas(G_VERYLOW)
// 0x20s
case KECCAK256 => s.UseGas(CostExpandRange(s,2,0,1) + CostKeccak256(s))
// 0x30s: Environment Information
case ADDRESS => s.UseGas(G_BASE)
case BALANCE => s.UseGas(CostExtAccount(s))
case ORIGIN => s.UseGas(G_BASE)
case CALLER => s.UseGas(G_BASE)
case CALLVALUE => s.UseGas(G_BASE)
case CALLDATALOAD => s.UseGas(G_VERYLOW)
case CALLDATASIZE => s.UseGas(G_BASE)
case CALLDATACOPY => s.UseGas(CostExpandRange(s,3,0,2) + G_VERYLOW + CostCopy(s,2))
case CODESIZE => s.UseGas(G_BASE)
case CODECOPY => s.UseGas(CostExpandRange(s,3,0,2) + G_VERYLOW + CostCopy(s,2))
case GASPRICE => s.UseGas(G_BASE)
case EXTCODESIZE => s.UseGas(CostExtAccount(s))
case EXTCODECOPY => s.UseGas(CostExpandRange(s,4,1,3) + CostExtAccount(s) + CostCopy(s,3))
case RETURNDATASIZE => s.UseGas(G_BASE)
case RETURNDATACOPY => s.UseGas(CostExpandRange(s,3,0,2) + G_VERYLOW + CostCopy(s,2))
case EXTCODEHASH => s.UseGas(CostExtAccount(s))
// 0x40s: Block Information
case BLOCKHASH => s.UseGas(G_BLOCKHASH)
case COINBASE => s.UseGas(G_BASE)
case TIMESTAMP => s.UseGas(G_BASE)
case NUMBER => s.UseGas(G_BASE)
case DIFFICULTY => s.UseGas(G_BASE)
case GASLIMIT => s.UseGas(G_BASE)
case CHAINID => s.UseGas(G_BASE)
case SELFBALANCE => s.UseGas(G_LOW)
case BASEFEE => s.UseGas(G_BASE)
// 0x50s: Stack, Memory, Storage and Flow
case POP => s.UseGas(G_BASE)
case MLOAD => s.UseGas(CostExpandBytes(s,1,0,32) + G_VERYLOW)
case MSTORE => s.UseGas(CostExpandBytes(s,2,0,32) + G_VERYLOW)
case MSTORE8 => s.UseGas(CostExpandBytes(s,2,0,1) + G_VERYLOW)
case SLOAD => s.UseGas(CostSLoad(s))
case SSTORE => s.UseGas(CostSStore(s)) // for now
case JUMP => s.UseGas(G_MID)
case JUMPI => s.UseGas(G_HIGH) // for now
case PC => s.UseGas(G_BASE)
case MSIZE => s.UseGas(G_BASE)
case GAS => s.UseGas(G_BASE)
case JUMPDEST => s.UseGas(G_JUMPDEST)
case TLOAD => s.UseGas(G_WARMACCESS)
case TSTORE => s.UseGas(G_WARMACCESS)
case MCOPY => s.UseGas(CostExpandDoubleRange(s,3,0,2,1,2) + G_VERYLOW + CostCopy(s,2))
case PUSH0 => s.UseGas(G_BASE)
// 0x60s & 0x70s: Push operations
case PUSH1 => s.UseGas(G_VERYLOW)
case PUSH2 => s.UseGas(G_VERYLOW)
case PUSH3 => s.UseGas(G_VERYLOW)
case PUSH4 => s.UseGas(G_VERYLOW)
case PUSH5 => s.UseGas(G_VERYLOW)
case PUSH6 => s.UseGas(G_VERYLOW)
case PUSH7 => s.UseGas(G_VERYLOW)
case PUSH8 => s.UseGas(G_VERYLOW)
case PUSH9 => s.UseGas(G_VERYLOW)
case PUSH10 => s.UseGas(G_VERYLOW)
case PUSH11 => s.UseGas(G_VERYLOW)
case PUSH12 => s.UseGas(G_VERYLOW)
case PUSH13 => s.UseGas(G_VERYLOW)
case PUSH14 => s.UseGas(G_VERYLOW)
case PUSH15 => s.UseGas(G_VERYLOW)
case PUSH16 => s.UseGas(G_VERYLOW)
case PUSH17 => s.UseGas(G_VERYLOW)
case PUSH18 => s.UseGas(G_VERYLOW)
case PUSH19 => s.UseGas(G_VERYLOW)
case PUSH20 => s.UseGas(G_VERYLOW)
case PUSH21 => s.UseGas(G_VERYLOW)
case PUSH22 => s.UseGas(G_VERYLOW)
case PUSH23 => s.UseGas(G_VERYLOW)
case PUSH24 => s.UseGas(G_VERYLOW)
case PUSH25 => s.UseGas(G_VERYLOW)
case PUSH26 => s.UseGas(G_VERYLOW)
case PUSH27 => s.UseGas(G_VERYLOW)
case PUSH28 => s.UseGas(G_VERYLOW)
case PUSH29 => s.UseGas(G_VERYLOW)
case PUSH30 => s.UseGas(G_VERYLOW)
case PUSH31 => s.UseGas(G_VERYLOW)
case PUSH32 => s.UseGas(G_VERYLOW)
// 0x80s: Duplicate operations
case DUP1 => s.UseGas(G_VERYLOW)
case DUP2 => s.UseGas(G_VERYLOW)
case DUP3 => s.UseGas(G_VERYLOW)
case DUP4 => s.UseGas(G_VERYLOW)
case DUP5 => s.UseGas(G_VERYLOW)
case DUP6 => s.UseGas(G_VERYLOW)
case DUP7 => s.UseGas(G_VERYLOW)
case DUP8 => s.UseGas(G_VERYLOW)
case DUP9 => s.UseGas(G_VERYLOW)
case DUP10 => s.UseGas(G_VERYLOW)
case DUP11 => s.UseGas(G_VERYLOW)
case DUP12 => s.UseGas(G_VERYLOW)
case DUP13 => s.UseGas(G_VERYLOW)
case DUP14 => s.UseGas(G_VERYLOW)
case DUP15 => s.UseGas(G_VERYLOW)
case DUP16 => s.UseGas(G_VERYLOW)
// 0x90s: Exchange operations
case SWAP1 => s.UseGas(G_VERYLOW)
case SWAP2 => s.UseGas(G_VERYLOW)
case SWAP3 => s.UseGas(G_VERYLOW)
case SWAP4 => s.UseGas(G_VERYLOW)
case SWAP5 => s.UseGas(G_VERYLOW)
case SWAP6 => s.UseGas(G_VERYLOW)
case SWAP7 => s.UseGas(G_VERYLOW)
case SWAP8 => s.UseGas(G_VERYLOW)
case SWAP9 => s.UseGas(G_VERYLOW)
case SWAP10 => s.UseGas(G_VERYLOW)
case SWAP11 => s.UseGas(G_VERYLOW)
case SWAP12 => s.UseGas(G_VERYLOW)
case SWAP13 => s.UseGas(G_VERYLOW)
case SWAP14 => s.UseGas(G_VERYLOW)
case SWAP15 => s.UseGas(G_VERYLOW)
case SWAP16 => s.UseGas(G_VERYLOW)
// 0xA0s: Log operations
case LOG0 => s.UseGas(CostExpandRange(s,2,0,1) + CostLog(s,0))
case LOG1 => s.UseGas(CostExpandRange(s,3,0,1) + CostLog(s,1))
case LOG2 => s.UseGas(CostExpandRange(s,4,0,1) + CostLog(s,2))
case LOG3 => s.UseGas(CostExpandRange(s,5,0,1) + CostLog(s,3))
case LOG4 => s.UseGas(CostExpandRange(s,6,0,1) + CostLog(s,4))
// 0xf0
case CREATE => s.UseGas(CostExpandRange(s,3,1,2) + CostCreate(s))
case CALL => s.UseGas(CostExpandDoubleRange(s,7,3,4,5,6) + CallCost(s))
case CALLCODE => s.UseGas(CostExpandDoubleRange(s,7,3,4,5,6) + CallCodeCost(s))
case RETURN => s.UseGas(CostExpandRange(s,2,0,1) + G_ZERO)
case DELEGATECALL => s.UseGas(CostExpandDoubleRange(s,6,2,3,4,5) + DelegateCallCost(s))
case CREATE2 => s.UseGas(CostExpandRange(s,4,1,2) + CostCreate2(s))
case STATICCALL => s.UseGas(CostExpandDoubleRange(s,6,2,3,4,5) + StaticCallCost(s))
case REVERT => s.UseGas(CostExpandRange(s,2,0,1) + G_ZERO)
case SELFDESTRUCT => s.UseGas(CostSelfDestruct(s))
case _ => ERROR(INVALID_OPCODE)
}
/**
* Execute a given bytecode from the executing state. This assumes gas has
* already been deducted. Again, this may or may not result in an executing
* state, depending on whether the necessary conditions for execution were
* met. For example, executing an instruction (e.g. ADD) which requires
* operands on the stack when there are no operands on the stack will result
* in an error state.
*/
function ExecuteBytecode(op: u8, st: ExecutingState): State {
match op
case STOP => Bytecode.Stop(st)
case ADD => Bytecode.Add(st)
case MUL => Bytecode.Mul(st)
case SUB => Bytecode.Sub(st)
case DIV => Bytecode.Div(st)
case SDIV => Bytecode.SDiv(st)
case MOD => Bytecode.Mod(st)
case SMOD => Bytecode.SMod(st)
case ADDMOD => Bytecode.AddMod(st)
case MULMOD => Bytecode.MulMod(st)
case EXP => Bytecode.Exp(st)
case SIGNEXTEND => Bytecode.SignExtend(st)
// 0x10s: Comparison & Bitwise Logic
case LT => Bytecode.Lt(st)
case GT => Bytecode.Gt(st)
case SLT => Bytecode.SLt(st)
case SGT => Bytecode.SGt(st)
case EQ => Bytecode.Eq(st)
case ISZERO => Bytecode.IsZero(st)
case AND => Bytecode.And(st)
case OR => Bytecode.Or(st)
case XOR => Bytecode.Xor(st)
case NOT => Bytecode.Not(st)
case BYTE => Bytecode.Byte(st)
case SHL => Bytecode.Shl(st)
case SHR => Bytecode.Shr(st)
case SAR => Bytecode.Sar(st)
// 0x20s
case KECCAK256 => Bytecode.Keccak256(st)
// 0x30s: Environment Information
case ADDRESS => Bytecode.Address(st)
case BALANCE => Bytecode.Balance(st)
case ORIGIN => Bytecode.Origin(st)
case CALLER => Bytecode.Caller(st)
case CALLVALUE => Bytecode.CallValue(st)
case CALLDATALOAD => Bytecode.CallDataLoad(st)
case CALLDATASIZE => Bytecode.CallDataSize(st)
case CALLDATACOPY => Bytecode.CallDataCopy(st)
case CODESIZE => Bytecode.CodeSize(st)
case CODECOPY => Bytecode.CodeCopy(st)
case GASPRICE => Bytecode.GasPrice(st)
case EXTCODESIZE => Bytecode.ExtCodeSize(st)
case EXTCODECOPY => Bytecode.ExtCodeCopy(st)
case RETURNDATASIZE => Bytecode.ReturnDataSize(st)
case RETURNDATACOPY => Bytecode.ReturnDataCopy(st)
case EXTCODEHASH => Bytecode.ExtCodeHash(st)
// 0x40s: Block Information
case BLOCKHASH => Bytecode.BlockHash(st)
case COINBASE => Bytecode.CoinBase(st)
case TIMESTAMP => Bytecode.TimeStamp(st)
case NUMBER => Bytecode.Number(st)
case DIFFICULTY => Bytecode.Difficulty(st)
case GASLIMIT => Bytecode.GasLimit(st)
case CHAINID => Bytecode.ChainID(st)
case SELFBALANCE => Bytecode.SelfBalance(st)
case BASEFEE => Bytecode.BaseFee(st)
// 0x50s: Stack, Memory, Storage and Flow
case POP => Bytecode.Pop(st)
case MLOAD => Bytecode.MLoad(st)
case MSTORE => Bytecode.MStore(st)
case MSTORE8 => Bytecode.MStore8(st)
case SLOAD => Bytecode.SLoad(st)
case SSTORE => Bytecode.SStore(st)
case JUMP => Bytecode.Jump(st)
case JUMPI => Bytecode.JumpI(st)
case PC => Bytecode.Pc(st)
case MSIZE => Bytecode.MSize(st)
case GAS => Bytecode.Gas(st)
case JUMPDEST => Bytecode.JumpDest(st)
case TLOAD => Bytecode.TLoad(st)
case TSTORE => Bytecode.TStore(st)
case MCOPY => Bytecode.MCopy(st)
case PUSH0 => Bytecode.Push0(st)
// 0x60s & 0x70s: Push operations
case PUSH1 => Bytecode.Push(st,1)
case PUSH2 => Bytecode.Push(st,2)
case PUSH3 => Bytecode.Push(st,3)
case PUSH4 => Bytecode.Push(st,4)
case PUSH5 => Bytecode.Push(st,5)
case PUSH6 => Bytecode.Push(st,6)
case PUSH7 => Bytecode.Push(st,7)
case PUSH8 => Bytecode.Push(st,8)
case PUSH9 => Bytecode.Push(st,9)
case PUSH10 => Bytecode.Push(st,10)
case PUSH11 => Bytecode.Push(st,11)
case PUSH12 => Bytecode.Push(st,12)
case PUSH13 => Bytecode.Push(st,13)
case PUSH14 => Bytecode.Push(st,14)
case PUSH15 => Bytecode.Push(st,15)
case PUSH16 => Bytecode.Push(st,16)
case PUSH17 => Bytecode.Push(st,17)
case PUSH18 => Bytecode.Push(st,18)
case PUSH19 => Bytecode.Push(st,19)
case PUSH20 => Bytecode.Push(st,20)
case PUSH21 => Bytecode.Push(st,21)
case PUSH22 => Bytecode.Push(st,22)
case PUSH23 => Bytecode.Push(st,23)
case PUSH24 => Bytecode.Push(st,24)
case PUSH25 => Bytecode.Push(st,25)
case PUSH26 => Bytecode.Push(st,26)
case PUSH27 => Bytecode.Push(st,27)
case PUSH28 => Bytecode.Push(st,28)
case PUSH29 => Bytecode.Push(st,29)
case PUSH30 => Bytecode.Push(st,30)
case PUSH31 => Bytecode.Push(st,31)
case PUSH32 => Bytecode.Push(st,32)
// 0x80s: Duplicate operations
case DUP1 => Bytecode.Dup(st, 1)
case DUP2 => Bytecode.Dup(st, 2)
case DUP3 => Bytecode.Dup(st, 3)
case DUP4 => Bytecode.Dup(st, 4)
case DUP5 => Bytecode.Dup(st, 5)
case DUP6 => Bytecode.Dup(st, 6)
case DUP7 => Bytecode.Dup(st, 7)
case DUP8 => Bytecode.Dup(st, 8)
case DUP9 => Bytecode.Dup(st, 9)
case DUP10 => Bytecode.Dup(st, 10)
case DUP11 => Bytecode.Dup(st, 11)
case DUP12 => Bytecode.Dup(st, 12)
case DUP13 => Bytecode.Dup(st, 13)
case DUP14 => Bytecode.Dup(st, 14)
case DUP15 => Bytecode.Dup(st, 15)
case DUP16 => Bytecode.Dup(st, 16)
// 0x90s: Exchange operations
case SWAP1 => Bytecode.Swap(st, 1)
case SWAP2 => Bytecode.Swap(st, 2)
case SWAP3 => Bytecode.Swap(st, 3)
case SWAP4 => Bytecode.Swap(st, 4)
case SWAP5 => Bytecode.Swap(st, 5)
case SWAP6 => Bytecode.Swap(st, 6)
case SWAP7 => Bytecode.Swap(st, 7)
case SWAP8 => Bytecode.Swap(st, 8)
case SWAP9 => Bytecode.Swap(st, 9)
case SWAP10 => Bytecode.Swap(st, 10)
case SWAP11 => Bytecode.Swap(st, 11)
case SWAP12 => Bytecode.Swap(st, 12)
case SWAP13 => Bytecode.Swap(st, 13)
case SWAP14 => Bytecode.Swap(st, 14)
case SWAP15 => Bytecode.Swap(st, 15)
case SWAP16 => Bytecode.Swap(st, 16)
// 0xA0s: Log operations
case LOG0 => Bytecode.LogN(st,0)
case LOG1 => Bytecode.LogN(st,1)
case LOG2 => Bytecode.LogN(st,2)
case LOG3 => Bytecode.LogN(st,3)
case LOG4 => Bytecode.LogN(st,4)
// 0xf0
case CREATE => Bytecode.Create(st)
case CALL => Bytecode.Call(st)
case CALLCODE => Bytecode.CallCode(st)
case RETURN => Bytecode.Return(st)
case DELEGATECALL => Bytecode.DelegateCall(st)
case CREATE2 => Bytecode.Create2(st)
case STATICCALL => Bytecode.StaticCall(st)
case REVERT => Bytecode.Revert(st)
case SELFDESTRUCT => Bytecode.SelfDestruct(st)
case _ => ERROR(INVALID_OPCODE)
}
}