holocene: operator fee

crates/optimism/src/handler_register.rs

@@ -47,6 +47,7 @@ where
         // Refund is calculated differently then mainnet.
         handler.execution.last_frame_return = Arc::new(last_frame_return::<EvmWiringT, SPEC>);
         handler.post_execution.refund = Arc::new(refund::<EvmWiringT, SPEC>);
+        handler.post_execution.reimburse_caller = Arc::new(reimburse_caller::<EvmWiringT, SPEC>);
         handler.post_execution.reward_beneficiary =
             Arc::new(reward_beneficiary::<EvmWiringT, SPEC>);
         // In case of halt of deposit transaction return Error.
@@ -177,6 +178,39 @@ pub fn refund<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
     }
 }
 
+/// Reimburse the transaction caller.
+#[inline]
+pub fn reimburse_caller<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
+    context: &mut Context<EvmWiringT>,
+    gas: &Gas,
+) -> EVMResultGeneric<(), EvmWiringT> {
+    mainnet::reimburse_caller::<EvmWiringT>(context, gas)?;
+    let caller = *context.evm.env.tx.caller();
+    let caller_account = context
+        .evm
+        .inner
+        .journaled_state
+        .load_account(caller, &mut context.evm.inner.db)
+        .map_err(EVMError::Database)?;
+    // In additional to the normal transaction fee, additionally refund the caller
+    // for the operator fee.
+    let operator_fee_refund = context
+        .evm
+        .inner
+        .chain
+        .l1_block_info()
+        .expect("L1BlockInfo should be loaded")
+        .operator_fee_refund(gas, SPEC::OPTIMISM_SPEC_ID);
+
+    caller_account.data.info.balance = caller_account
+        .data
+        .info
+        .balance
+        .saturating_add(operator_fee_refund);
+
+    Ok(())
+}
+
 /// Load precompiles for Optimism chain.
 #[inline]
 pub fn load_precompiles<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
@@ -248,6 +282,7 @@ pub fn deduct_caller<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
 
     // If the transaction is not a deposit transaction, subtract the L1 data fee from the
     // caller's balance directly after minting the requested amount of ETH.
+    // Additionally deduct the operator fee from the caller's account.
     if context.evm.inner.env.tx.source_hash().is_none() {
         // get envelope
         let Some(enveloped_tx) = &context.evm.inner.env.tx.enveloped_tx() else {
@@ -273,6 +308,22 @@ pub fn deduct_caller<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
             ));
         }
         caller_account.info.balance = caller_account.info.balance.saturating_sub(tx_l1_cost);
+
+        // Deduct the operator fee from the caller's account.
+        let gas_limit = U256::from(context.evm.inner.env.tx.gas_limit());
+
+        let operator_fee_charge = context
+            .evm
+            .inner
+            .chain
+            .l1_block_info()
+            .expect("L1BlockInfo should be loaded")
+            .operator_fee_charge(gas_limit, SPEC::OPTIMISM_SPEC_ID);
+
+        caller_account.info.balance = caller_account
+            .info
+            .balance
+            .saturating_sub(operator_fee_charge);
     }
     Ok(())
 }
@@ -306,6 +357,10 @@ pub fn reward_beneficiary<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
         };
 
         let l1_cost = l1_block_info.calculate_tx_l1_cost(enveloped_tx, SPEC::OPTIMISM_SPEC_ID);
+        let operator_fee_cost = l1_block_info.operator_fee_charge(
+            U256::from(gas.spent() - gas.refunded() as u64),
+            SPEC::OPTIMISM_SPEC_ID,
+        );
 
         // Send the L1 cost of the transaction to the L1 Fee Vault.
         let mut l1_fee_vault_account = context
@@ -332,6 +387,23 @@ pub fn reward_beneficiary<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
             .block
             .basefee()
             .mul(U256::from(gas.spent() - gas.refunded() as u64));
+
+        // Send the operator fee of the transaction to the coinbase.
+        let beneficiary = *context.evm.env.block.coinbase();
+
+        // Don't need to `mark_touch` as it's already been done in `reward_beneficiary`.
+        let coinbase_account = context
+            .evm
+            .inner
+            .journaled_state
+            .load_account(beneficiary, &mut context.evm.inner.db)
+            .map_err(EVMError::Database)?;
+
+        coinbase_account.data.info.balance = coinbase_account
+            .data
+            .info
+            .balance
+            .saturating_add(operator_fee_cost);
     }
     Ok(())
 }
@@ -428,7 +500,9 @@ pub fn end<EvmWiringT: OptimismWiring, SPEC: OptimismSpec>(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{BedrockSpec, L1BlockInfo, LatestSpec, OptimismEvmWiring, RegolithSpec};
+    use crate::{
+        BedrockSpec, HoloceneSpec, L1BlockInfo, LatestSpec, OptimismEvmWiring, RegolithSpec,
+    };
     use database::InMemoryDB;
     use revm::{
         database_interface::EmptyDB,
@@ -630,6 +704,40 @@ mod tests {
         assert_eq!(account.info.balance, U256::from(1));
     }
 
+    #[test]
+    fn test_remove_operator_cost() {
+        let caller = Address::ZERO;
+        let mut db = InMemoryDB::default();
+        db.insert_account_info(
+            caller,
+            AccountInfo {
+                balance: U256::from(151),
+                ..Default::default()
+            },
+        );
+        let mut context = Context::<TestMemOpWiring>::new_with_db(db);
+        *context.evm.chain.l1_block_info_mut() = Some(L1BlockInfo {
+            operator_fee_scalar: Some(U256::from(10_000_000)),
+            operator_fee_constant: Some(U256::from(50)),
+            ..Default::default()
+        });
+        context.evm.inner.env.tx.base.gas_limit = 10;
+
+        // operator fee cost is operator_fee_scalar * gas_limit / 1e6 + operator_fee_constant
+        // 10_000_000 * 10 / 1_000_000 + 50 = 150
+        context.evm.inner.env.tx.enveloped_tx = Some(bytes!("FACADE"));
+        deduct_caller::<TestMemOpWiring, HoloceneSpec>(&mut context).unwrap();
+
+        // Check the account balance is updated.
+        let account = context
+            .evm
+            .inner
+            .journaled_state
+            .load_account(caller, &mut context.evm.inner.db)
+            .unwrap();
+        assert_eq!(account.info.balance, U256::from(1));
+    }
+
     #[test]
     fn test_remove_l1_cost_lack_of_funds() {
         let caller = Address::ZERO;

crates/optimism/src/l1block.rs

@@ -2,6 +2,7 @@ use crate::fast_lz::flz_compress_len;
 use core::ops::Mul;
 use revm::{
     database_interface::Database,
+    interpreter::Gas,
     primitives::{address, Address, U256},
 };
 
@@ -16,6 +17,17 @@ const BASE_FEE_SCALAR_OFFSET: usize = 16;
 /// The two 4-byte Ecotone fee scalar values are packed into the same storage slot as the 8-byte sequence number.
 /// Byte offset within the storage slot of the 4-byte blobBaseFeeScalar attribute.
 const BLOB_BASE_FEE_SCALAR_OFFSET: usize = 20;
+/// The two 8-byte Holocene operator fee scalar values are similarly packed. Byte offset within
+/// the storage slot of the 8-byte operatorFeeScalar attribute.
+const OPERATOR_FEE_SCALAR_OFFSET: usize = 4;
+/// The two 8-byte Holocene operator fee scalar values are similarly packed. Byte offset within
+/// the storage slot of the 8-byte operatorFeeConstant attribute.
+const OPERATOR_FEE_CONSTANT_OFFSET: usize = 8;
+
+/// The fixed point decimal scaling factor associated with the operator fee scalar.
+///
+/// Allows users to use 6 decimal points of precision when specifying the operator_fee_scalar.
+const OPERATOR_FEE_SCALAR_DECIMAL: u64 = 1_000_000;
 
 const L1_BASE_FEE_SLOT: U256 = U256::from_limbs([1u64, 0, 0, 0]);
 const L1_OVERHEAD_SLOT: U256 = U256::from_limbs([5u64, 0, 0, 0]);
@@ -63,8 +75,12 @@ pub struct L1BlockInfo {
     pub l1_blob_base_fee: Option<U256>,
     /// The current L1 blob base fee scalar. None if Ecotone is not activated.
     pub l1_blob_base_fee_scalar: Option<U256>,
+    /// The current L1 blob base fee. None if Holocene is not activated, except if `empty_scalars` is `true`.
+    pub operator_fee_scalar: Option<U256>,
+    /// The current L1 blob base fee scalar. None if Holocene is not activated.
+    pub operator_fee_constant: Option<U256>,
     /// True if Ecotone is activated, but the L1 fee scalars have not yet been set.
-    pub(crate) empty_scalars: bool,
+    pub(crate) empty_ecotone_scalars: bool,
 }
 
 impl L1BlockInfo {
@@ -107,21 +123,50 @@ impl L1BlockInfo {
 
             // Check if the L1 fee scalars are empty. If so, we use the Bedrock cost function. The L1 fee overhead is
             // only necessary if `empty_scalars` is true, as it was deprecated in Ecotone.
-            let empty_scalars = l1_blob_base_fee.is_zero()
+            let empty_ecotone_scalars = l1_blob_base_fee.is_zero()
                 && l1_fee_scalars[BASE_FEE_SCALAR_OFFSET..BLOB_BASE_FEE_SCALAR_OFFSET + 4]
                     == EMPTY_SCALARS;
-            let l1_fee_overhead = empty_scalars
+
+            let l1_fee_overhead = empty_ecotone_scalars
                 .then(|| db.storage(L1_BLOCK_CONTRACT, L1_OVERHEAD_SLOT))
                 .transpose()?;
 
-            Ok(L1BlockInfo {
-                l1_base_fee,
-                l1_base_fee_scalar,
-                l1_blob_base_fee: Some(l1_blob_base_fee),
-                l1_blob_base_fee_scalar: Some(l1_blob_base_fee_scalar),
-                empty_scalars,
-                l1_fee_overhead,
-            })
+            // Pre-holocene L1 block info
+            if !spec_id.is_enabled_in(OptimismSpecId::HOLOCENE) {
+                Ok(L1BlockInfo {
+                    l1_base_fee,
+                    l1_base_fee_scalar,
+                    l1_blob_base_fee: Some(l1_blob_base_fee),
+                    l1_blob_base_fee_scalar: Some(l1_blob_base_fee_scalar),
+                    empty_ecotone_scalars,
+                    l1_fee_overhead,
+                    ..Default::default()
+                })
+            } else {
+                // Post-holocene L1 block info
+                // The `operator_fee_scalar` is stored as a big endian u32 at
+                // OPERATOR_FEE_SCALAR_OFFSET.
+                let operator_fee_scalar = U256::from_be_slice(
+                    l1_fee_scalars[OPERATOR_FEE_SCALAR_OFFSET..OPERATOR_FEE_SCALAR_OFFSET + 4]
+                        .as_ref(),
+                );
+                // The `operator_fee_constant` is stored as a big endian u64 at
+                // OPERATOR_FEE_CONSTANT_OFFSET.
+                let operator_fee_constant = U256::from_be_slice(
+                    l1_fee_scalars[OPERATOR_FEE_CONSTANT_OFFSET..OPERATOR_FEE_CONSTANT_OFFSET + 8]
+                        .as_ref(),
+                );
+                Ok(L1BlockInfo {
+                    l1_base_fee,
+                    l1_base_fee_scalar,
+                    l1_blob_base_fee: Some(l1_blob_base_fee),
+                    l1_blob_base_fee_scalar: Some(l1_blob_base_fee_scalar),
+                    empty_ecotone_scalars,
+                    l1_fee_overhead,
+                    operator_fee_scalar: Some(operator_fee_scalar),
+                    operator_fee_constant: Some(operator_fee_constant),
+                })
+            }
         }
     }
 
@@ -157,6 +202,44 @@ impl L1BlockInfo {
         rollup_data_gas_cost
     }
 
+    /// Calculate the operator fee for executing this transaction.
+    ///
+    /// Introduced in holocene. Prior to holocene, the operator fee is always zero.
+    pub fn operator_fee_charge(&self, gas_limit: U256, spec_id: OptimismSpecId) -> U256 {
+        if !spec_id.is_enabled_in(OptimismSpecId::HOLOCENE) {
+            return U256::ZERO;
+        }
+        let operator_fee_scalar = self
+            .operator_fee_scalar
+            .expect("Missing operator fee scalar for holocene L1 Block");
+        let operator_fee_constant = self
+            .operator_fee_constant
+            .expect("Missing operator fee constant for holocene L1 Block");
+
+        let product = gas_limit.saturating_mul(operator_fee_scalar)
+            / (U256::from(OPERATOR_FEE_SCALAR_DECIMAL));
+
+        product.saturating_add(operator_fee_constant)
+    }
+
+    /// Calculate the operator fee for executing this transaction.
+    ///
+    /// Introduced in holocene. Prior to holocene, the operator fee is always zero.
+    pub fn operator_fee_refund(&self, gas: &Gas, spec_id: OptimismSpecId) -> U256 {
+        if !spec_id.is_enabled_in(OptimismSpecId::HOLOCENE) {
+            return U256::ZERO;
+        }
+
+        let operator_fee_scalar = self
+            .operator_fee_scalar
+            .expect("Missing operator fee scalar for holocene L1 Block");
+
+        // We're computing the difference between two operator fees, so no need to include the
+        // constant.
+
+        operator_fee_scalar.saturating_mul(U256::from(gas.remaining() + gas.refunded() as u64))
+    }
+
     // Calculate the estimated compressed transaction size in bytes, scaled by 1e6.
     // This value is computed based on the following formula:
     // max(minTransactionSize, intercept + fastlzCoef*fastlzSize)
@@ -209,7 +292,7 @@ impl L1BlockInfo {
         // There is an edgecase where, for the very first Ecotone block (unless it is activated at Genesis), we must
         // use the Bedrock cost function. To determine if this is the case, we can check if the Ecotone parameters are
         // unset.
-        if self.empty_scalars {
+        if self.empty_ecotone_scalars {
             return self.calculate_tx_l1_cost_bedrock(input, spec_id);
         }
 
@@ -367,7 +450,7 @@ mod tests {
         assert_eq!(gas_cost, U256::ZERO);
 
         // If the scalars are empty, the bedrock cost function should be used.
-        l1_block_info.empty_scalars = true;
+        l1_block_info.empty_ecotone_scalars = true;
         let input = bytes!("FACADE");
         let gas_cost = l1_block_info.calculate_tx_l1_cost(&input, OptimismSpecId::ECOTONE);
         assert_eq!(gas_cost, U256::from(1048));

crates/optimism/src/lib.rs

@@ -15,7 +15,7 @@ mod spec;
 
 pub use handler_register::{
     deduct_caller, end, last_frame_return, load_accounts, load_precompiles,
-    optimism_handle_register, output, refund, reward_beneficiary, validate_env,
+    optimism_handle_register, output, refund, reimburse_caller, reward_beneficiary, validate_env,
     validate_tx_against_state,
 };
 pub use l1block::{L1BlockInfo, BASE_FEE_RECIPIENT, L1_BLOCK_CONTRACT, L1_FEE_RECIPIENT};