implement precompile override and moveTo feature

core/vm/contracts.go

@@ -138,7 +138,21 @@ func (p PrecompiledContracts) Copy() PrecompiledContracts {
 	return c
 }
 
-// ActivePrecompiles returns the precompiles enabled with the current configuration.
+// ActivePrecompiledContracts returns precompiled contracts enabled with the current configuration.
+func ActivePrecompiledContracts(rules params.Rules) PrecompiledContracts {
+	switch {
+	case rules.IsBerlin:
+		return PrecompiledContractsBerlin
+	case rules.IsIstanbul:
+		return PrecompiledContractsIstanbul
+	case rules.IsByzantium:
+		return PrecompiledContractsByzantium
+	default:
+		return PrecompiledContractsHomestead
+	}
+}
+
+// ActivePrecompiles returns the precompile addresses enabled with the current configuration.
 func ActivePrecompiles(rules params.Rules) []common.Address {
 	switch {
 	case rules.IsBerlin:

core/vm/evm.go

@@ -123,24 +123,18 @@ func NewEVM(blockCtx BlockContext, txCtx TxContext, statedb StateDB, chainConfig
 		chainConfig: chainConfig,
 		chainRules:  chainConfig.Rules(blockCtx.BlockNumber, blockCtx.Random != nil, blockCtx.Time),
 	}
-	switch {
-	case evm.chainRules.IsBerlin:
-		evm.precompiles = PrecompiledContractsBerlin.Copy()
-	case evm.chainRules.IsIstanbul:
-		evm.precompiles = PrecompiledContractsIstanbul.Copy()
-	case evm.chainRules.IsByzantium:
-		evm.precompiles = PrecompiledContractsByzantium.Copy()
-	default:
-		evm.precompiles = PrecompiledContractsHomestead.Copy()
-	}
-	// ECRecoverCode can be set only through RPC calls
-	if config.DisableECRecover {
-		delete(evm.precompiles, common.BytesToAddress([]byte{1}))
-	}
+	evm.precompiles = ActivePrecompiledContracts(evm.chainRules)
 	evm.interpreter = NewEVMInterpreter(evm)
 	return evm
 }
 
+// SetPrecompiles sets the precompiled contracts for the EVM.
+// This method is only used through RPC calls.
+// It is not thread-safe.
+func (evm *EVM) SetPrecompiles(precompiles PrecompiledContracts) {
+	evm.precompiles = precompiles
+}
+
 // Reset resets the EVM with a new transaction context.Reset
 // This is not threadsafe and should only be done very cautiously.
 func (evm *EVM) Reset(txCtx TxContext, statedb StateDB) {

internal/ethapi/api.go

@@ -873,6 +873,7 @@ type OverrideAccount struct {
 	Balance   **hexutil.Big                `json:"balance"`
 	State     *map[common.Hash]common.Hash `json:"state"`
 	StateDiff *map[common.Hash]common.Hash `json:"stateDiff"`
+	MoveTo    *common.Address              `json:"moveTo"`
 }
 
 // StateOverride is the collection of overridden accounts.
@@ -917,6 +918,80 @@ func (diff *StateOverride) Apply(state *state.StateDB) error {
 	return nil
 }
 
+// ApplyMulticall overrides the fields of specified accounts into the given state.
+func (diff *StateOverride) ApplyMulticall(state *state.StateDB, precompiles vm.PrecompiledContracts) error {
+	if diff == nil {
+		return nil
+	}
+	for addr, account := range *diff {
+		p, isPrecompile := precompiles[addr]
+		// The MoveTo feature makes it possible to replace precompiles and EVM
+		// contracts in all the following configurations:
+		// 1. Precompile -> Precompile
+		// 2. Precompile -> EVM contract
+		// 3. EVM contract -> Precompile
+		// 4. EVM contract -> EVM contract
+		if account.MoveTo != nil {
+			if isPrecompile {
+				// Clear destination account which may be an EVM contract.
+				if !state.Empty(*account.MoveTo) {
+					state.SetCode(*account.MoveTo, nil)
+					state.SetNonce(*account.MoveTo, 0)
+					state.SetBalance(*account.MoveTo, big.NewInt(0))
+					state.SetStorage(*account.MoveTo, map[common.Hash]common.Hash{})
+				}
+				// If destination is a precompile, it will be simply replaced.
+				precompiles[*account.MoveTo] = p
+			} else {
+				state.SetBalance(*account.MoveTo, state.GetBalance(addr))
+				state.SetNonce(*account.MoveTo, state.GetNonce(addr))
+				state.SetCode(*account.MoveTo, state.GetCode(addr))
+				// TODO: copy storage over
+				//state.SetState(*account.MoveTo, state.GetState(addr))
+				// Clear source storage
+				state.SetStorage(addr, map[common.Hash]common.Hash{})
+				if precompiles[*account.MoveTo] != nil {
+					delete(precompiles, *account.MoveTo)
+				}
+			}
+		}
+		if isPrecompile {
+			// Now that the contract is moved it can be deleted.
+			delete(precompiles, addr)
+		}
+		// Override account nonce.
+		if account.Nonce != nil {
+			state.SetNonce(addr, uint64(*account.Nonce))
+		}
+		// Override account(contract) code.
+		if account.Code != nil {
+			state.SetCode(addr, *account.Code)
+		}
+		// Override account balance.
+		if account.Balance != nil {
+			state.SetBalance(addr, (*big.Int)(*account.Balance))
+		}
+		if account.State != nil && account.StateDiff != nil {
+			return fmt.Errorf("account %s has both 'state' and 'stateDiff'", addr.Hex())
+		}
+		// Replace entire state if caller requires.
+		if account.State != nil {
+			state.SetStorage(addr, *account.State)
+		}
+		// Apply state diff into specified accounts.
+		if account.StateDiff != nil {
+			for key, value := range *account.StateDiff {
+				state.SetState(addr, key, value)
+			}
+		}
+	}
+	// Now finalize the changes. Finalize is normally performed between transactions.
+	// By using finalize, the overrides are semantically behaving as
+	// if they were created in a transaction just before the tracing occur.
+	state.Finalise(false)
+	return nil
+}
+
 // BlockOverrides is a set of header fields to override.
 type BlockOverrides struct {
 	Number     *hexutil.Big
@@ -1013,16 +1088,19 @@ func DoCall(ctx context.Context, b Backend, args TransactionArgs, blockNrOrHash
 	// Make sure the context is cancelled when the call has completed
 	// this makes sure resources are cleaned up.
 	defer cancel()
-	return doCall(ctx, b, args, state, header, timeout, new(core.GasPool).AddGas(globalGasCap), &blockCtx, &vm.Config{NoBaseFee: true})
+	return doCall(ctx, b, args, state, header, timeout, new(core.GasPool).AddGas(globalGasCap), &blockCtx, &vm.Config{NoBaseFee: true}, nil)
 }
 
-func doCall(ctx context.Context, b Backend, args TransactionArgs, state *state.StateDB, header *types.Header, timeout time.Duration, gp *core.GasPool, blockContext *vm.BlockContext, vmConfig *vm.Config) (*core.ExecutionResult, error) {
+func doCall(ctx context.Context, b Backend, args TransactionArgs, state *state.StateDB, header *types.Header, timeout time.Duration, gp *core.GasPool, blockContext *vm.BlockContext, vmConfig *vm.Config, precompiles vm.PrecompiledContracts) (*core.ExecutionResult, error) {
 	// Get a new instance of the EVM.
 	msg, err := args.ToMessage(gp.Gas(), header.BaseFee)
 	if err != nil {
 		return nil, err
 	}
 	evm, vmError := b.GetEVM(ctx, msg, state, header, vmConfig, blockContext)
+	if precompiles != nil {
+		evm.SetPrecompiles(precompiles)
+	}
 
 	// Wait for the context to be done and cancel the evm. Even if the
 	// EVM has finished, cancelling may be done (repeatedly)
@@ -1170,9 +1248,12 @@ func (s *BlockChainAPI) MulticallV1(ctx context.Context, opts multicallOpts, blo
 		globalGasCap = s.b.RPCGasCap()
 		gp           = new(core.GasPool).AddGas(globalGasCap)
 		prevNumber   = header.Number.Uint64()
+		blockContext = core.NewEVMBlockContext(header, NewChainContext(ctx, s.b), nil)
+		rules        = s.b.ChainConfig().Rules(blockContext.BlockNumber, blockContext.Random != nil, blockContext.Time)
+		precompiles  = vm.ActivePrecompiledContracts(rules).Copy()
 	)
 	for bi, block := range blocks {
-		blockContext := core.NewEVMBlockContext(header, NewChainContext(ctx, s.b), nil)
+		blockContext = core.NewEVMBlockContext(header, NewChainContext(ctx, s.b), nil)
 		if block.BlockOverrides != nil {
 			block.BlockOverrides.Apply(&blockContext)
 		}
@@ -1182,7 +1263,7 @@ func (s *BlockChainAPI) MulticallV1(ctx context.Context, opts multicallOpts, blo
 		}
 		prevNumber = blockContext.BlockNumber.Uint64()
 		// State overrides are applied prior to execution of a block
-		if err := block.StateOverrides.Apply(state); err != nil {
+		if err := block.StateOverrides.ApplyMulticall(state, precompiles); err != nil {
 			return nil, err
 		}
 		// ECRecover replacement code will be fetched from statedb and executed as a normal EVM bytecode.
@@ -1211,7 +1292,7 @@ func (s *BlockChainAPI) MulticallV1(ctx context.Context, opts multicallOpts, blo
 			if opts.TraceTransfers {
 				vmConfig.Tracer = newTracer()
 			}
-			result, err := doCall(ctx, s.b, call, state, header, timeout, gp, &blockContext, vmConfig)
+			result, err := doCall(ctx, s.b, call, state, header, timeout, gp, &blockContext, vmConfig, precompiles)
 			if err != nil {
 				results[bi].Calls[i] = callResult{Error: err.Error(), Status: hexutil.Uint64(types.ReceiptStatusFailed)}
 				continue

internal/ethapi/api_test.go

@@ -1018,17 +1018,19 @@ func TestMulticallV1(t *testing.T) {
 						// }
 						Code: hex2Bytes("6040516000815260006020820152600060408201526000606082015260208160808360015afa60008103603157600080fd5b601482f3"),
 					},
+					common.BytesToAddress([]byte{0x01}): OverrideAccount{
+						// Yul code that returns the address of the caller.
+						// object "Test" {
+						//    code {
+						//        let c := caller()
+						//        mstore(0, c)
+						//        return(0xc, 0x14)
+						//    }
+						// }
+						Code: hex2Bytes("33806000526014600cf3"),
+					},
 				},
 				BlockOverrides: &BlockOverrides{},
-				// Yul code that returns the address of the caller.
-				// object "Test" {
-				//    code {
-				//        let c := caller()
-				//        mstore(0, c)
-				//        return(0xc, 0x14)
-				//    }
-				// }
-				ECRecoverOverride: hex2Bytes("33806000526014600cf3"),
 				Calls: []TransactionArgs{{
 					From: &randomAccounts[0].addr,
 					To:   &randomAccounts[2].addr,