From be12392fbad9f4a861130a347e6bcf07a5c34974 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@users.noreply.github.com>
Date: Tue, 28 Nov 2017 20:05:49 +0100
Subject: [PATCH] core/vm: track 63/64 call gas off stack (#15563)
* core/vm: track 63/64 call gas off stack
Gas calculations in gasCall* relayed the available gas for calls by
replacing it on the stack. This lead to inconsistent traces, which we
papered over by copying the pre-execution stack in trace mode.
This change relays available gas using a temporary variable, off the
stack, and allows removing the weird copy.
* core/vm: remove stackCopy
* core/vm: pop call gas into pool
* core/vm: to -> addr
---
core/vm/evm.go | 4 +++
core/vm/gas_table.go | 46 +++++--------------------
core/vm/instructions.go | 76 ++++++++++++++++++-----------------------
core/vm/interpreter.go | 28 ++++++---------
4 files changed, 55 insertions(+), 99 deletions(-)
diff --git a/core/vm/evm.go b/core/vm/evm.go
index 093c7d4c1..344435f73 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -104,6 +104,10 @@ type EVM struct {
// abort is used to abort the EVM calling operations
// NOTE: must be set atomically
abort int32
+ // callGasTemp holds the gas available for the current call. This is needed because the
+ // available gas is calculated in gasCall* according to the 63/64 rule and later
+ // applied in opCall*.
+ callGasTemp uint64
}
// NewEVM retutrns a new EVM . The returned EVM is not thread safe and should
diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go
index 0d8e295a5..ff109af57 100644
--- a/core/vm/gas_table.go
+++ b/core/vm/gas_table.go
@@ -342,19 +342,11 @@ func gasCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem
return 0, errGasUintOverflow
}
- cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+ evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
- // Replace the stack item with the new gas calculation. This means that
- // either the original item is left on the stack or the item is replaced by:
- // (availableGas - gas) * 63 / 64
- // We replace the stack item so that it's available when the opCall instruction is
- // called. This information is otherwise lost due to the dependency on *current*
- // available gas.
- stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
- if gas, overflow = math.SafeAdd(gas, cg); overflow {
+ if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
return 0, errGasUintOverflow
}
return gas, nil
@@ -374,19 +366,11 @@ func gasCallCode(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack,
return 0, errGasUintOverflow
}
- cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+ evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
- // Replace the stack item with the new gas calculation. This means that
- // either the original item is left on the stack or the item is replaced by:
- // (availableGas - gas) * 63 / 64
- // We replace the stack item so that it's available when the opCall instruction is
- // called. This information is otherwise lost due to the dependency on *current*
- // available gas.
- stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
- if gas, overflow = math.SafeAdd(gas, cg); overflow {
+ if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
return 0, errGasUintOverflow
}
return gas, nil
@@ -436,18 +420,11 @@ func gasDelegateCall(gt params.GasTable, evm *EVM, contract *Contract, stack *St
return 0, errGasUintOverflow
}
- cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+ evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
- // Replace the stack item with the new gas calculation. This means that
- // either the original item is left on the stack or the item is replaced by:
- // (availableGas - gas) * 63 / 64
- // We replace the stack item so that it's available when the opCall instruction is
- // called.
- stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
- if gas, overflow = math.SafeAdd(gas, cg); overflow {
+ if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
return 0, errGasUintOverflow
}
return gas, nil
@@ -463,18 +440,11 @@ func gasStaticCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stac
return 0, errGasUintOverflow
}
- cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+ evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
if err != nil {
return 0, err
}
- // Replace the stack item with the new gas calculation. This means that
- // either the original item is left on the stack or the item is replaced by:
- // (availableGas - gas) * 63 / 64
- // We replace the stack item so that it's available when the opCall instruction is
- // called.
- stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
- if gas, overflow = math.SafeAdd(gas, cg); overflow {
+ if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
return 0, errGasUintOverflow
}
return gas, nil
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index b6d6e22c4..1d1585fca 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -603,24 +603,20 @@ func opCreate(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *S
}
func opCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
- gas := stack.pop().Uint64()
- // pop gas and value of the stack.
- addr, value := stack.pop(), stack.pop()
+ // Pop gas. The actual gas in in evm.callGasTemp.
+ evm.interpreter.intPool.put(stack.pop())
+ gas := evm.callGasTemp
+ // Pop other call parameters.
+ addr, value, inOffset, inSize, retOffset, retSize := stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
+ toAddr := common.BigToAddress(addr)
value = math.U256(value)
- // pop input size and offset
- inOffset, inSize := stack.pop(), stack.pop()
- // pop return size and offset
- retOffset, retSize := stack.pop(), stack.pop()
-
- address := common.BigToAddress(addr)
-
- // Get the arguments from the memory
+ // Get the arguments from the memory.
args := memory.Get(inOffset.Int64(), inSize.Int64())
if value.Sign() != 0 {
gas += params.CallStipend
}
- ret, returnGas, err := evm.Call(contract, address, args, gas, value)
+ ret, returnGas, err := evm.Call(contract, toAddr, args, gas, value)
if err != nil {
stack.push(new(big.Int))
} else {
@@ -636,25 +632,20 @@ func opCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Sta
}
func opCallCode(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
- gas := stack.pop().Uint64()
- // pop gas and value of the stack.
- addr, value := stack.pop(), stack.pop()
+ // Pop gas. The actual gas is in evm.callGasTemp.
+ evm.interpreter.intPool.put(stack.pop())
+ gas := evm.callGasTemp
+ // Pop other call parameters.
+ addr, value, inOffset, inSize, retOffset, retSize := stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
+ toAddr := common.BigToAddress(addr)
value = math.U256(value)
- // pop input size and offset
- inOffset, inSize := stack.pop(), stack.pop()
- // pop return size and offset
- retOffset, retSize := stack.pop(), stack.pop()
-
- address := common.BigToAddress(addr)
-
- // Get the arguments from the memory
+ // Get arguments from the memory.
args := memory.Get(inOffset.Int64(), inSize.Int64())
if value.Sign() != 0 {
gas += params.CallStipend
}
-
- ret, returnGas, err := evm.CallCode(contract, address, args, gas, value)
+ ret, returnGas, err := evm.CallCode(contract, toAddr, args, gas, value)
if err != nil {
stack.push(new(big.Int))
} else {
@@ -670,9 +661,13 @@ func opCallCode(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack
}
func opDelegateCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
- gas, to, inOffset, inSize, outOffset, outSize := stack.pop().Uint64(), stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
-
- toAddr := common.BigToAddress(to)
+ // Pop gas. The actual gas is in evm.callGasTemp.
+ evm.interpreter.intPool.put(stack.pop())
+ gas := evm.callGasTemp
+ // Pop other call parameters.
+ addr, inOffset, inSize, retOffset, retSize := stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
+ toAddr := common.BigToAddress(addr)
+ // Get arguments from the memory.
args := memory.Get(inOffset.Int64(), inSize.Int64())
ret, returnGas, err := evm.DelegateCall(contract, toAddr, args, gas)
@@ -682,30 +677,25 @@ func opDelegateCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, st
stack.push(big.NewInt(1))
}
if err == nil || err == errExecutionReverted {
- memory.Set(outOffset.Uint64(), outSize.Uint64(), ret)
+ memory.Set(retOffset.Uint64(), retSize.Uint64(), ret)
}
contract.Gas += returnGas
- evm.interpreter.intPool.put(to, inOffset, inSize, outOffset, outSize)
+ evm.interpreter.intPool.put(addr, inOffset, inSize, retOffset, retSize)
return ret, nil
}
func opStaticCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
- // pop gas
- gas := stack.pop().Uint64()
- // pop address
- addr := stack.pop()
- // pop input size and offset
- inOffset, inSize := stack.pop(), stack.pop()
- // pop return size and offset
- retOffset, retSize := stack.pop(), stack.pop()
-
- address := common.BigToAddress(addr)
-
- // Get the arguments from the memory
+ // Pop gas. The actual gas is in evm.callGasTemp.
+ evm.interpreter.intPool.put(stack.pop())
+ gas := evm.callGasTemp
+ // Pop other call parameters.
+ addr, inOffset, inSize, retOffset, retSize := stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
+ toAddr := common.BigToAddress(addr)
+ // Get arguments from the memory.
args := memory.Get(inOffset.Int64(), inSize.Int64())
- ret, returnGas, err := evm.StaticCall(contract, address, args, gas)
+ ret, returnGas, err := evm.StaticCall(contract, toAddr, args, gas)
if err != nil {
stack.push(new(big.Int))
} else {
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index ea5468f90..ac6000f97 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -138,16 +138,15 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
pc = uint64(0) // program counter
cost uint64
// copies used by tracer
- stackCopy = newstack() // stackCopy needed for Tracer since stack is mutated by 63/64 gas rule
- pcCopy uint64 // needed for the deferred Tracer
- gasCopy uint64 // for Tracer to log gas remaining before execution
- logged bool // deferred Tracer should ignore already logged steps
+ pcCopy uint64 // needed for the deferred Tracer
+ gasCopy uint64 // for Tracer to log gas remaining before execution
+ logged bool // deferred Tracer should ignore already logged steps
)
contract.Input = input
defer func() {
if err != nil && !logged && in.cfg.Debug {
- in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stackCopy, contract, in.evm.depth, err)
+ in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
}
}()
@@ -156,21 +155,14 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
// the execution of one of the operations or until the done flag is set by the
// parent context.
for atomic.LoadInt32(&in.evm.abort) == 0 {
- // Get the memory location of pc
- op = contract.GetOp(pc)
-
if in.cfg.Debug {
- logged = false
- pcCopy = pc
- gasCopy = contract.Gas
- stackCopy = newstack()
- for _, val := range stack.data {
- stackCopy.push(val)
- }
+ // Capture pre-execution values for tracing.
+ logged, pcCopy, gasCopy = false, pc, contract.Gas
}
- // Get the operation from the jump table matching the opcode and validate the
- // stack and make sure there enough stack items available to perform the operation
+ // Get the operation from the jump table and validate the stack to ensure there are
+ // enough stack items available to perform the operation.
+ op = contract.GetOp(pc)
operation := in.cfg.JumpTable[op]
if !operation.valid {
return nil, fmt.Errorf("invalid opcode 0x%x", int(op))
@@ -211,7 +203,7 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
}
if in.cfg.Debug {
- in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stackCopy, contract, in.evm.depth, err)
+ in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
logged = true
}
--
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