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// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package vm
import (
"errors"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/params"
)
const (
ColdAccountAccessCostEIP2929 = uint64(2600) // COLD_ACCOUNT_ACCESS_COST
ColdSloadCostEIP2929 = uint64(2100) // COLD_SLOAD_COST
WarmStorageReadCostEIP2929 = uint64(100) // WARM_STORAGE_READ_COST
)
// gasSStoreEIP2929 implements gas cost for SSTORE according to EIP-2929"
//
// When calling SSTORE, check if the (address, storage_key) pair is in accessed_storage_keys.
// If it is not, charge an additional COLD_SLOAD_COST gas, and add the pair to accessed_storage_keys.
// Additionally, modify the parameters defined in EIP 2200 as follows:
//
// Parameter Old value New value
// SLOAD_GAS 800 = WARM_STORAGE_READ_COST
// SSTORE_RESET_GAS 5000 5000 - COLD_SLOAD_COST
//
//The other parameters defined in EIP 2200 are unchanged.
// see gasSStoreEIP2200(...) in core/vm/gas_table.go for more info about how EIP 2200 is specified
func gasSStoreEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
// If we fail the minimum gas availability invariant, fail (0)
if contract.Gas <= params.SstoreSentryGasEIP2200 {
return 0, errors.New("not enough gas for reentrancy sentry")
}
// Gas sentry honoured, do the actual gas calculation based on the stored value
var (
y, x = stack.Back(1), stack.peek()
slot = common.Hash(x.Bytes32())
current = evm.StateDB.GetState(contract.Address(), slot)
cost = uint64(0)
)
// Check slot presence in the access list
if addrPresent, slotPresent := evm.StateDB.SlotInAccessList(contract.Address(), slot); !slotPresent {
cost = ColdSloadCostEIP2929
// If the caller cannot afford the cost, this change will be rolled back
evm.StateDB.AddSlotToAccessList(contract.Address(), slot)
if !addrPresent {
// Once we're done with YOLOv2 and schedule this for mainnet, might
// be good to remove this panic here, which is just really a
// canary to have during testing
panic("impossible case: address was not present in access list during sstore op")
}
}
value := common.Hash(y.Bytes32())
if current == value { // noop (1)
// EIP 2200 original clause:
// return params.SloadGasEIP2200, nil
return cost + WarmStorageReadCostEIP2929, nil // SLOAD_GAS
}
original := evm.StateDB.GetCommittedState(contract.Address(), x.Bytes32())
if original == current {
if original == (common.Hash{}) { // create slot (2.1.1)
return cost + params.SstoreSetGasEIP2200, nil
}
if value == (common.Hash{}) { // delete slot (2.1.2b)
evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
}
// EIP-2200 original clause:
// return params.SstoreResetGasEIP2200, nil // write existing slot (2.1.2)
return cost + (params.SstoreResetGasEIP2200 - ColdSloadCostEIP2929), nil // write existing slot (2.1.2)
}
if original != (common.Hash{}) {
if current == (common.Hash{}) { // recreate slot (2.2.1.1)
evm.StateDB.SubRefund(params.SstoreClearsScheduleRefundEIP2200)
} else if value == (common.Hash{}) { // delete slot (2.2.1.2)
evm.StateDB.AddRefund(params.SstoreClearsScheduleRefundEIP2200)
}
}
if original == value {
if original == (common.Hash{}) { // reset to original inexistent slot (2.2.2.1)
// EIP 2200 Original clause:
//evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - params.SloadGasEIP2200)
evm.StateDB.AddRefund(params.SstoreSetGasEIP2200 - WarmStorageReadCostEIP2929)
} else { // reset to original existing slot (2.2.2.2)
// EIP 2200 Original clause:
// evm.StateDB.AddRefund(params.SstoreResetGasEIP2200 - params.SloadGasEIP2200)
// - SSTORE_RESET_GAS redefined as (5000 - COLD_SLOAD_COST)
// - SLOAD_GAS redefined as WARM_STORAGE_READ_COST
// Final: (5000 - COLD_SLOAD_COST) - WARM_STORAGE_READ_COST
evm.StateDB.AddRefund((params.SstoreResetGasEIP2200 - ColdSloadCostEIP2929) - WarmStorageReadCostEIP2929)
}
}
// EIP-2200 original clause:
//return params.SloadGasEIP2200, nil // dirty update (2.2)
return cost + WarmStorageReadCostEIP2929, nil // dirty update (2.2)
}
// gasSLoadEIP2929 calculates dynamic gas for SLOAD according to EIP-2929
// For SLOAD, if the (address, storage_key) pair (where address is the address of the contract
// whose storage is being read) is not yet in accessed_storage_keys,
// charge 2100 gas and add the pair to accessed_storage_keys.
// If the pair is already in accessed_storage_keys, charge 100 gas.
func gasSLoadEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
loc := stack.peek()
slot := common.Hash(loc.Bytes32())
// Check slot presence in the access list
if _, slotPresent := evm.StateDB.SlotInAccessList(contract.Address(), slot); !slotPresent {
// If the caller cannot afford the cost, this change will be rolled back
// If he does afford it, we can skip checking the same thing later on, during execution
evm.StateDB.AddSlotToAccessList(contract.Address(), slot)
return ColdSloadCostEIP2929, nil
}
return WarmStorageReadCostEIP2929, nil
}
// gasExtCodeCopyEIP2929 implements extcodecopy according to EIP-2929
// EIP spec:
// > If the target is not in accessed_addresses,
// > charge COLD_ACCOUNT_ACCESS_COST gas, and add the address to accessed_addresses.
// > Otherwise, charge WARM_STORAGE_READ_COST gas.
func gasExtCodeCopyEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
// memory expansion first (dynamic part of pre-2929 implementation)
gas, err := gasExtCodeCopy(evm, contract, stack, mem, memorySize)
if err != nil {
return 0, err
}
addr := common.Address(stack.peek().Bytes20())
// Check slot presence in the access list
if !evm.StateDB.AddressInAccessList(addr) {
evm.StateDB.AddAddressToAccessList(addr)
var overflow bool
// We charge (cold-warm), since 'warm' is already charged as constantGas
if gas, overflow = math.SafeAdd(gas, ColdAccountAccessCostEIP2929-WarmStorageReadCostEIP2929); overflow {
return 0, ErrGasUintOverflow
}
return gas, nil
}
return gas, nil
}
// gasEip2929AccountCheck checks whether the first stack item (as address) is present in the access list.
// If it is, this method returns '0', otherwise 'cold-warm' gas, presuming that the opcode using it
// is also using 'warm' as constant factor.
// This method is used by:
// - extcodehash,
// - extcodesize,
// - (ext) balance
func gasEip2929AccountCheck(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
addr := common.Address(stack.peek().Bytes20())
// Check slot presence in the access list
if !evm.StateDB.AddressInAccessList(addr) {
// If the caller cannot afford the cost, this change will be rolled back
evm.StateDB.AddAddressToAccessList(addr)
// The warm storage read cost is already charged as constantGas
return ColdAccountAccessCostEIP2929 - WarmStorageReadCostEIP2929, nil
}
return 0, nil
}
func makeCallVariantGasCallEIP2929(oldCalculator gasFunc) gasFunc {
return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
addr := common.Address(stack.Back(1).Bytes20())
// Check slot presence in the access list
if !evm.StateDB.AddressInAccessList(addr) {
evm.StateDB.AddAddressToAccessList(addr)
// The WarmStorageReadCostEIP2929 (100) is already deducted in the form of a constant cost
if !contract.UseGas(ColdAccountAccessCostEIP2929 - WarmStorageReadCostEIP2929) {
return 0, ErrOutOfGas
}
}
// Now call the old calculator, which takes into account
// - create new account
// - transfer value
// - memory expansion
// - 63/64ths rule
return oldCalculator(evm, contract, stack, mem, memorySize)
}
}
var (
gasCallEIP2929 = makeCallVariantGasCallEIP2929(gasCall)
gasDelegateCallEIP2929 = makeCallVariantGasCallEIP2929(gasDelegateCall)
gasStaticCallEIP2929 = makeCallVariantGasCallEIP2929(gasStaticCall)
gasCallCodeEIP2929 = makeCallVariantGasCallEIP2929(gasCallCode)
)
func gasSelfdestructEIP2929(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
var (
gas uint64
address = common.Address(stack.peek().Bytes20())
)
if !evm.StateDB.AddressInAccessList(address) {
// If the caller cannot afford the cost, this change will be rolled back
evm.StateDB.AddAddressToAccessList(address)
gas = ColdAccountAccessCostEIP2929
}
// if empty and transfers value
if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).Sign() != 0 {
gas += params.CreateBySelfdestructGas
}
if !evm.StateDB.HasSuicided(contract.Address()) {
evm.StateDB.AddRefund(params.SelfdestructRefundGas)
}
return gas, nil
}