core/vm: report gas used warming 7702 delegation targets correctly in tracer

Author: lightclient

core/vm/operations_acl.go

@@ -253,55 +253,61 @@ var (
 
 func makeCallVariantGasCallEIP7702(oldCalculator gasFunc) gasFunc {
 	return func(evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
-		addr := common.Address(stack.Back(1).Bytes20())
+		var (
+			total uint64 // total dynamic gas used
+			addr  = common.Address(stack.Back(1).Bytes20())
+		)
+
 		// Check slot presence in the access list
-		warmAccess := evm.StateDB.AddressInAccessList(addr)
-		// The WarmStorageReadCostEIP2929 (100) is already deducted in the form of a constant cost, so
-		// the cost to charge for cold access, if any, is Cold - Warm
-		coldCost := params.ColdAccountAccessCostEIP2929 - params.WarmStorageReadCostEIP2929
-		if !warmAccess {
+		if !evm.StateDB.AddressInAccessList(addr) {
 			evm.StateDB.AddAddressToAccessList(addr)
+			// The WarmStorageReadCostEIP2929 (100) is already deducted in the form of a constant cost, so
+			// the cost to charge for cold access, if any, is Cold - Warm
+			coldCost := params.ColdAccountAccessCostEIP2929 - params.WarmStorageReadCostEIP2929
 			// Charge the remaining difference here already, to correctly calculate available
 			// gas for call
 			if !contract.UseGas(coldCost, evm.Config.Tracer, tracing.GasChangeCallStorageColdAccess) {
 				return 0, ErrOutOfGas
 			}
+			total += coldCost
 		}
 
 		// Check if code is a delegation and if so, charge for resolution.
-		if addr, ok := types.ParseDelegation(evm.StateDB.GetCode(addr)); ok {
+		if target, ok := types.ParseDelegation(evm.StateDB.GetCode(addr)); ok {
 			var cost uint64
-			if evm.StateDB.AddressInAccessList(addr) {
-				cost += params.WarmStorageReadCostEIP2929
+			if evm.StateDB.AddressInAccessList(target) {
+				cost = params.WarmStorageReadCostEIP2929
 			} else {
-				evm.StateDB.AddAddressToAccessList(addr)
-				cost += params.ColdAccountAccessCostEIP2929
+				evm.StateDB.AddAddressToAccessList(target)
+				cost = params.ColdAccountAccessCostEIP2929
 			}
 			if !contract.UseGas(cost, evm.Config.Tracer, tracing.GasChangeCallStorageColdAccess) {
 				return 0, ErrOutOfGas
 			}
-			coldCost += cost
+			total += cost
 		}
+
 		// Now call the old calculator, which takes into account
 		// - create new account
 		// - transfer value
 		// - memory expansion
 		// - 63/64ths rule
-		gas, err := oldCalculator(evm, contract, stack, mem, memorySize)
-		if warmAccess || err != nil {
-			return gas, err
+		old, err := oldCalculator(evm, contract, stack, mem, memorySize)
+		if err != nil {
+			return old, err
 		}
-		// In case of a cold access, we temporarily add the cold charge back, and also
-		// add it to the returned gas. By adding it to the return, it will be charged
-		// outside of this function, as part of the dynamic gas, and that will make it
-		// also become correctly reported to tracers.
-		contract.Gas += coldCost
+
+		// Temporarily add the gas charge back to the contract and return value. By
+		// adding it to the return, it will be charged outside of this function, as
+		// part of the dynamic gas. This will ensure it is correctly reported to
+		// tracers.
+		contract.Gas += total
 
 		var overflow bool
-		if gas, overflow = math.SafeAdd(gas, coldCost); overflow {
+		if total, overflow = math.SafeAdd(old, total); overflow {
 			return 0, ErrGasUintOverflow
 		}
-		return gas, nil
+		return total, nil
 	}
 }
 

core/vm/runtime/runtime_test.go

@@ -866,3 +866,83 @@ func BenchmarkTracerStepVsCallFrame(b *testing.B) {
 	benchmarkNonModifyingCode(10000000, code, "tracer-step-10M", stepTracer, b)
 	benchmarkNonModifyingCode(10000000, code, "tracer-call-frame-10M", callFrameTracer, b)
 }
+
+// TestDelegatedAccountAccessCost tests that calling an account with an EIP-7702
+// delegation designator incurs the correct amount of gas based on the tracer.
+func TestDelegatedAccountAccessCost(t *testing.T) {
+	statedb, _ := state.New(types.EmptyRootHash, state.NewDatabaseForTesting())
+	statedb.SetCode(common.HexToAddress("0xff"), types.AddressToDelegation(common.HexToAddress("0xaa")))
+	statedb.SetCode(common.HexToAddress("0xaa"), program.New().Return(0, 0).Bytes())
+
+	for i, tc := range []struct {
+		code []byte
+		step int
+		want uint64
+	}{
+		{ // CALL(0xff)
+			code: []byte{
+				byte(vm.PUSH1), 0x0,
+				byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1),
+				byte(vm.PUSH1), 0xff, byte(vm.DUP1), byte(vm.CALL), byte(vm.POP),
+			},
+			step: 7,
+			want: 5455,
+		},
+		{ // CALLCODE(0xff)
+			code: []byte{
+				byte(vm.PUSH1), 0x0,
+				byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1),
+				byte(vm.PUSH1), 0xff, byte(vm.DUP1), byte(vm.CALLCODE), byte(vm.POP),
+			},
+			step: 7,
+			want: 5455,
+		},
+		{ // DELEGATECALL(0xff)
+			code: []byte{
+				byte(vm.PUSH1), 0x0,
+				byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1),
+				byte(vm.PUSH1), 0xff, byte(vm.DUP1), byte(vm.DELEGATECALL), byte(vm.POP),
+			},
+			step: 6,
+			want: 5455,
+		},
+		{ // STATICCALL(0xff)
+			code: []byte{
+				byte(vm.PUSH1), 0x0,
+				byte(vm.DUP1), byte(vm.DUP1), byte(vm.DUP1),
+				byte(vm.PUSH1), 0xff, byte(vm.DUP1), byte(vm.STATICCALL), byte(vm.POP),
+			},
+			step: 6,
+			want: 5455,
+		},
+		{ // SELFDESTRUCT(0xff): should not be affected by resolution
+			code: []byte{
+				byte(vm.PUSH1), 0xff, byte(vm.SELFDESTRUCT),
+			},
+			step: 1,
+			want: 7600,
+		},
+	} {
+		var step = 0
+		var have = uint64(0)
+		Execute(tc.code, nil, &Config{
+			ChainConfig: params.MergedTestChainConfig,
+			State:       statedb,
+			EVMConfig: vm.Config{
+				Tracer: &tracing.Hooks{
+					OnOpcode: func(pc uint64, op byte, gas, cost uint64, scope tracing.OpContext, rData []byte, depth int, err error) {
+						// Uncomment to investigate failures:
+						t.Logf("%d: %v %d", step, vm.OpCode(op).String(), cost)
+						if step == tc.step {
+							have = cost
+						}
+						step++
+					},
+				},
+			},
+		})
+		if want := tc.want; have != want {
+			t.Fatalf("testcase %d, gas report wrong, step %d, have %d want %d", i, tc.step, have, want)
+		}
+	}
+}