Align GasWeightMapping with Substrate do_pre_dispatch logic

frame/ethereum/src/lib.rs

@@ -256,10 +256,13 @@ pub mod pallet {
 		OriginFor<T>: Into<Result<RawOrigin, OriginFor<T>>>,
 	{
 		/// Transact an Ethereum transaction.
-		#[pallet::weight(<T as pallet_evm::Config>::GasWeightMapping::gas_to_weight({
-			let transaction_data: TransactionData = transaction.into();
-			transaction_data.gas_limit.unique_saturated_into()
-		}))]
+		#[pallet::weight({
+			let without_base_extrinsic_weight = true;
+			<T as pallet_evm::Config>::GasWeightMapping::gas_to_weight({
+				let transaction_data: TransactionData = transaction.into();
+				transaction_data.gas_limit.unique_saturated_into()
+			}, without_base_extrinsic_weight)
+		})]
 		pub fn transact(
 			origin: OriginFor<T>,
 			transaction: Transaction,
@@ -604,6 +607,7 @@ impl<T: Config> Pallet<T> {
 		Ok(PostDispatchInfo {
 			actual_weight: Some(T::GasWeightMapping::gas_to_weight(
 				used_gas.unique_saturated_into(),
+				true,
 			)),
 			pays_fee: Pays::No,
 		})

frame/ethereum/src/mock.rs

@@ -138,6 +138,7 @@ parameter_types! {
 	pub const ChainId: u64 = 42;
 	pub const EVMModuleId: PalletId = PalletId(*b"py/evmpa");
 	pub const BlockGasLimit: U256 = U256::MAX;
+	pub const WeightPerGas: u64 = 20_000;
 }
 
 pub struct HashedAddressMapping;
@@ -152,7 +153,8 @@ impl AddressMapping<AccountId32> for HashedAddressMapping {
 
 impl pallet_evm::Config for Test {
 	type FeeCalculator = FixedGasPrice;
-	type GasWeightMapping = ();
+	type GasWeightMapping = pallet_evm::FixedGasWeightMapping<Self>;
+	type WeightPerGas = WeightPerGas;
 	type CallOrigin = EnsureAddressTruncated;
 	type WithdrawOrigin = EnsureAddressTruncated;
 	type AddressMapping = HashedAddressMapping;

frame/ethereum/src/tests/eip1559.rs

@@ -83,8 +83,10 @@ fn transaction_with_gas_limit_greater_than_max_extrinsic_should_fail_pre_dispatc
 	let limits: frame_system::limits::BlockWeights =
 		<Test as frame_system::Config>::BlockWeights::get();
 	let max_extrinsic = limits.get(DispatchClass::Normal).max_extrinsic.unwrap();
-	let max_extrinsic_gas =
-		<Test as pallet_evm::Config>::GasWeightMapping::weight_to_gas(max_extrinsic);
+	let base_extrinsic = limits.get(DispatchClass::Normal).base_extrinsic;
+	let max_extrinsic_gas = <Test as pallet_evm::Config>::GasWeightMapping::weight_to_gas(
+		max_extrinsic + base_extrinsic,
+	);
 
 	ext.execute_with(|| {
 		let transaction = EIP1559UnsignedTransaction {

frame/evm/precompile/dispatch/src/lib.rs

@@ -73,7 +73,7 @@ where
 		}
 
 		if let Some(gas) = target_gas {
-			let valid_weight = info.weight <= T::GasWeightMapping::gas_to_weight(gas);
+			let valid_weight = info.weight <= T::GasWeightMapping::gas_to_weight(gas, false);
 			if !valid_weight {
 				return Err(PrecompileFailure::Error {
 					exit_status: ExitError::OutOfGas,

frame/evm/precompile/dispatch/src/mock.rs

@@ -136,10 +136,12 @@ impl FindAuthor<H160> for FindAuthorTruncated {
 }
 parameter_types! {
 	pub BlockGasLimit: U256 = U256::max_value();
+	pub WeightPerGas: u64 = 20_000;
 }
 impl pallet_evm::Config for Test {
 	type FeeCalculator = FixedGasPrice;
-	type GasWeightMapping = ();
+	type GasWeightMapping = pallet_evm::FixedGasWeightMapping<Self>;
+	type WeightPerGas = WeightPerGas;
 
 	type CallOrigin = EnsureAddressRoot<Self::AccountId>;
 	type WithdrawOrigin = EnsureAddressNever<Self::AccountId>;

frame/evm/src/lib.rs

@@ -114,6 +114,9 @@ pub mod pallet {
 		/// Maps Ethereum gas to Substrate weight.
 		type GasWeightMapping: GasWeightMapping;
 
+		/// Weight corresponding to a gas unit.
+		type WeightPerGas: Get<u64>;
+
 		/// Block number to block hash.
 		type BlockHashMapping: BlockHashMapping;
 
@@ -176,7 +179,10 @@ pub mod pallet {
 		}
 
 		/// Issue an EVM call operation. This is similar to a message call transaction in Ethereum.
-		#[pallet::weight(T::GasWeightMapping::gas_to_weight(*gas_limit))]
+		#[pallet::weight({
+			let without_base_extrinsic_weight = true;
+			T::GasWeightMapping::gas_to_weight(*gas_limit, without_base_extrinsic_weight)
+		})]
 		pub fn call(
 			origin: OriginFor<T>,
 			source: H160,
@@ -231,14 +237,18 @@ pub mod pallet {
 			Ok(PostDispatchInfo {
 				actual_weight: Some(T::GasWeightMapping::gas_to_weight(
 					info.used_gas.unique_saturated_into(),
+					true,
 				)),
 				pays_fee: Pays::No,
 			})
 		}
 
 		/// Issue an EVM create operation. This is similar to a contract creation transaction in
 		/// Ethereum.
-		#[pallet::weight(T::GasWeightMapping::gas_to_weight(*gas_limit))]
+		#[pallet::weight({
+			let without_base_extrinsic_weight = true;
+			T::GasWeightMapping::gas_to_weight(*gas_limit, without_base_extrinsic_weight)
+		})]
 		pub fn create(
 			origin: OriginFor<T>,
 			source: H160,
@@ -303,13 +313,17 @@ pub mod pallet {
 			Ok(PostDispatchInfo {
 				actual_weight: Some(T::GasWeightMapping::gas_to_weight(
 					info.used_gas.unique_saturated_into(),
+					true,
 				)),
 				pays_fee: Pays::No,
 			})
 		}
 
 		/// Issue an EVM create2 operation.
-		#[pallet::weight(T::GasWeightMapping::gas_to_weight(*gas_limit))]
+		#[pallet::weight({
+			let without_base_extrinsic_weight = true;
+			T::GasWeightMapping::gas_to_weight(*gas_limit, without_base_extrinsic_weight)
+		})]
 		pub fn create2(
 			origin: OriginFor<T>,
 			source: H160,
@@ -376,6 +390,7 @@ pub mod pallet {
 			Ok(PostDispatchInfo {
 				actual_weight: Some(T::GasWeightMapping::gas_to_weight(
 					info.used_gas.unique_saturated_into(),
+					true,
 				)),
 				pays_fee: Pays::No,
 			})
@@ -618,16 +633,25 @@ impl<T: Config> BlockHashMapping for SubstrateBlockHashMapping<T> {
 
 /// A mapping function that converts Ethereum gas to Substrate weight
 pub trait GasWeightMapping {
-	fn gas_to_weight(gas: u64) -> Weight;
+	fn gas_to_weight(gas: u64, without_base_weight: bool) -> Weight;
 	fn weight_to_gas(weight: Weight) -> u64;
 }
 
-impl GasWeightMapping for () {
-	fn gas_to_weight(gas: u64) -> Weight {
-		gas as Weight
+pub struct FixedGasWeightMapping<T>(sp_std::marker::PhantomData<T>);
+impl<T: Config> GasWeightMapping for FixedGasWeightMapping<T> {
+	fn gas_to_weight(gas: u64, without_base_weight: bool) -> Weight {
+		let mut weight = gas.saturating_mul(T::WeightPerGas::get());
+		if without_base_weight {
+			weight = weight.saturating_sub(
+				T::BlockWeights::get()
+					.get(frame_support::weights::DispatchClass::Normal)
+					.base_extrinsic,
+			);
+		}
+		weight
 	}
 	fn weight_to_gas(weight: Weight) -> u64 {
-		weight as u64
+		weight.wrapping_div(T::WeightPerGas::get())
 	}
 }
 

frame/evm/src/mock.rs

@@ -124,10 +124,12 @@ impl FindAuthor<H160> for FindAuthorTruncated {
 }
 parameter_types! {
 	pub BlockGasLimit: U256 = U256::max_value();
+	pub WeightPerGas: u64 = 20_000;
 }
 impl crate::Config for Test {
 	type FeeCalculator = FixedGasPrice;
-	type GasWeightMapping = ();
+	type GasWeightMapping = crate::FixedGasWeightMapping<Self>;
+	type WeightPerGas = WeightPerGas;
 
 	type CallOrigin = EnsureAddressRoot<Self::AccountId>;
 	type WithdrawOrigin = EnsureAddressNever<Self::AccountId>;

template/runtime/src/lib.rs

@@ -40,8 +40,7 @@ use pallet_transaction_payment::CurrencyAdapter;
 use fp_rpc::TransactionStatus;
 use pallet_ethereum::{Call::transact, Transaction as EthereumTransaction};
 use pallet_evm::{
-	Account as EVMAccount, EnsureAddressTruncated, FeeCalculator, GasWeightMapping,
-	HashedAddressMapping, Runner,
+	Account as EVMAccount, EnsureAddressTruncated, FeeCalculator, HashedAddressMapping, Runner,
 };
 
 // A few exports that help ease life for downstream crates.
@@ -309,24 +308,16 @@ impl<F: FindAuthor<u32>> FindAuthor<H160> for FindAuthorTruncated<F> {
 	}
 }
 
-pub struct FixedGasWeightMapping;
-impl GasWeightMapping for FixedGasWeightMapping {
-	fn gas_to_weight(gas: u64) -> Weight {
-		gas.saturating_mul(WEIGHT_PER_GAS)
-	}
-	fn weight_to_gas(weight: Weight) -> u64 {
-		weight.wrapping_div(WEIGHT_PER_GAS)
-	}
-}
-
 parameter_types! {
 	pub BlockGasLimit: U256 = U256::from(NORMAL_DISPATCH_RATIO * MAXIMUM_BLOCK_WEIGHT / WEIGHT_PER_GAS);
 	pub PrecompilesValue: FrontierPrecompiles<Runtime> = FrontierPrecompiles::<_>::new();
+	pub WeightPerGas: u64 = 20_000;
 }
 
 impl pallet_evm::Config for Runtime {
 	type FeeCalculator = BaseFee;
-	type GasWeightMapping = FixedGasWeightMapping;
+	type GasWeightMapping = pallet_evm::FixedGasWeightMapping<Self>;
+	type WeightPerGas = WeightPerGas;
 	type BlockHashMapping = pallet_ethereum::EthereumBlockHashMapping<Self>;
 	type CallOrigin = EnsureAddressTruncated;
 	type WithdrawOrigin = EnsureAddressTruncated;
@@ -857,3 +848,16 @@ impl_runtime_apis! {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::{Runtime, WeightPerGas};
+	#[test]
+	fn configured_base_extrinsic_weight_is_evm_compatible() {
+		let min_ethereum_transaction_weight = WeightPerGas::get() * 21_000;
+		let base_extrinsic = <Runtime as frame_system::Config>::BlockWeights::get()
+			.get(frame_support::weights::DispatchClass::Normal)
+			.base_extrinsic;
+		assert!(base_extrinsic <= min_ethereum_transaction_weight);
+	}
+}

ts-tests/tests/test-gas.ts

@@ -40,8 +40,8 @@ describeWithFrontier("Frontier RPC (Gas)", (context) => {
 	// Those test are ordered. In general this should be avoided, but due to the time it takes
 	// to spin up a frontier node, it saves a lot of time.
 
-	// EXTRINSIC_GAS_LIMIT = [BLOCK_GAS_LIMIT - BLOCK_GAS_LIMIT * (NORMAL_DISPATCH_RATIO - AVERAGE_ON_INITIALIZE_RATIO) - EXTRINSIC_BASE_Weight] / WEIGHT_PER_GAS = (1_000_000_000_000 * 2 * (0.75-0.1) - 125_000_000) / 20000
-	const EXTRINSIC_GAS_LIMIT = 64995685;
+	// EXTRINSIC_GAS_LIMIT = [BLOCK_GAS_LIMIT - BLOCK_GAS_LIMIT * (NORMAL_DISPATCH_RATIO - AVERAGE_ON_INITIALIZE_RATIO)] / WEIGHT_PER_GAS = (1_000_000_000_000 * 2 * (0.75-0.1) - 125_000_000) / 20000
+	const EXTRINSIC_GAS_LIMIT = 65000000;
 
 	it("eth_estimateGas for contract creation", async function () {
 		// The value returned as an estimation by the evm with estimate mode ON.