nimbus-eth1/nimbus/vm2/precompiles.nim

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# Nimbus
# Copyright (c) 2018 Status Research & Development GmbH
# Licensed under either of
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
# http://www.apache.org/licenses/LICENSE-2.0)
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
# http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed except
# according to those terms.
import
./types,
./interpreter/[gas_meter, gas_costs, utils/utils_numeric, forks_list],
../errors, stint, eth/[keys, common], chronicles, tables, macros,
math, nimcrypto, bncurve/[fields, groups], ./blake2b_f, ./blscurve
type
PrecompileAddresses* = enum
# Frontier to Spurious Dragron
paEcRecover = 1
paSha256
paRipeMd160
paIdentity
# Byzantium and Constantinople
paModExp
paEcAdd
paEcMul
paPairing
# Istanbul
paBlake2bf
# Berlin
# EIP-2537: disabled
# reason: not included in berlin
# paBlsG1Add
# paBlsG1Mul
# paBlsG1MultiExp
# paBlsG2Add
# paBlsG2Mul
# paBlsG2MultiExp
# paBlsPairing
# paBlsMapG1
# paBlsMapG2
iterator activePrecompiles*(): EthAddress =
var res: EthAddress
for c in PrecompileAddresses.low..PrecompileAddresses.high:
res[^1] = c.byte
yield res
proc getSignature(computation: Computation): (array[32, byte], Signature) =
# input is Hash, V, R, S
template data: untyped = computation.msg.data
var bytes: array[65, byte] # will hold R[32], S[32], V[1], in that order
let maxPos = min(data.high, 127)
# if we don't have at minimum 64 bytes, there can be no valid V
if maxPos >= 63:
let v = data[63]
# check if V[32] is 27 or 28
if not (v.int in 27..28):
raise newException(ValidationError, "Invalid V in getSignature")
for x in 32..<63:
if data[x] != 0:
raise newException(ValidationError, "Invalid V in getSignature")
bytes[64] = v - 27
# if there is more data for R and S, copy it. Else, defaulted zeroes are
# used for R and S
if maxPos >= 64:
# Copy message data to buffer
bytes[0..(maxPos-64)] = data[64..maxPos]
let sig = Signature.fromRaw(bytes)
if sig.isErr:
raise newException(ValidationError, "Could not recover signature computation")
result[1] = sig[]
# extract message hash, only need to copy when there is a valid signature
result[0][0..31] = data[0..31]
else:
raise newException(ValidationError, "Invalid V in getSignature")
proc simpleDecode*(dst: var FQ2, src: openarray[byte]): bool {.noinit.} =
# bypassing FQ2.fromBytes
# because we want to check `value > modulus`
result = false
if dst.c1.fromBytes(src.toOpenArray(0, 31)) and
dst.c0.fromBytes(src.toOpenArray(32, 63)):
result = true
template simpleDecode*(dst: var FQ, src: openarray[byte]): bool =
fromBytes(dst, src)
proc getPoint[T: G1|G2](t: typedesc[T], data: openarray[byte]): Point[T] =
when T is G1:
const nextOffset = 32
var px, py: FQ
else:
const nextOffset = 64
var px, py: FQ2
if not px.simpleDecode(data.toOpenArray(0, nextOffset - 1)):
raise newException(ValidationError, "Could not get point value")
if not py.simpleDecode(data.toOpenArray(nextOffset, nextOffset * 2 - 1)):
raise newException(ValidationError, "Could not get point value")
if px.isZero() and py.isZero():
result = T.zero()
else:
var ap: AffinePoint[T]
if not ap.init(px, py):
raise newException(ValidationError, "Point is not on curve")
result = ap.toJacobian()
proc getFR(data: openarray[byte]): FR =
if not result.fromBytes2(data):
raise newException(ValidationError, "Could not get FR value")
proc ecRecover*(computation: Computation) =
computation.gasMeter.consumeGas(
GasECRecover,
reason="ECRecover Precompile")
var
(msgHash, sig) = computation.getSignature()
var pubkey = recover(sig, SkMessage(msgHash))
if pubkey.isErr:
raise newException(ValidationError, "Could not derive public key from computation")
computation.output.setLen(32)
computation.output[12..31] = pubkey[].toCanonicalAddress()
trace "ECRecover precompile", derivedKey = pubkey[].toCanonicalAddress()
proc sha256*(computation: Computation) =
let
wordCount = wordCount(computation.msg.data.len)
gasFee = GasSHA256 + wordCount * GasSHA256Word
computation.gasMeter.consumeGas(gasFee, reason="SHA256 Precompile")
computation.output = @(nimcrypto.sha_256.digest(computation.msg.data).data)
trace "SHA256 precompile", output = computation.output.toHex
proc ripemd160*(computation: Computation) =
let
wordCount = wordCount(computation.msg.data.len)
gasFee = GasRIPEMD160 + wordCount * GasRIPEMD160Word
computation.gasMeter.consumeGas(gasFee, reason="RIPEMD160 Precompile")
computation.output.setLen(32)
computation.output[12..31] = @(nimcrypto.ripemd160.digest(computation.msg.data).data)
trace "RIPEMD160 precompile", output = computation.output.toHex
proc identity*(computation: Computation) =
let
wordCount = wordCount(computation.msg.data.len)
gasFee = GasIdentity + wordCount * GasIdentityWord
computation.gasMeter.consumeGas(gasFee, reason="Identity Precompile")
computation.output = computation.msg.data
trace "Identity precompile", output = computation.output.toHex
proc modExpInternal(computation: Computation, baseLen, expLen, modLen: int, T: type StUint) =
template data: untyped {.dirty.} =
computation.msg.data
let
base = data.rangeToPadded[:T](96, 95 + baseLen, baseLen)
exp = data.rangeToPadded[:T](96 + baseLen, 95 + baseLen + expLen, expLen)
modulo = data.rangeToPadded[:T](96 + baseLen + expLen, 95 + baseLen + expLen + modLen, modLen)
# TODO: specs mentions that we should return in "M" format
# i.e. if Base and exp are uint512 and Modulo an uint256
# we should return a 256-bit big-endian byte array
# Force static evaluation
func zero(): array[T.bits div 8, byte] {.compileTime.} = discard
func one(): array[T.bits div 8, byte] {.compileTime.} =
when cpuEndian == bigEndian:
result[0] = 1
else:
result[^1] = 1
# Start with EVM special cases
let output = if modulo <= 1:
# If m == 0: EVM returns 0.
# If m == 1: we can shortcut that to 0 as well
zero()
elif exp.isZero():
# If 0^0: EVM returns 1
# For all x != 0, x^0 == 1 as well
one()
else:
powmod(base, exp, modulo).toByteArrayBE
# maximum output len is the same as modLen
# if it less than modLen, it will be zero padded at left
if output.len >= modLen:
computation.output = @(output[^modLen..^1])
else:
computation.output = newSeq[byte](modLen)
computation.output[^output.len..^1] = output[0..^1]
proc modExpFee(c: Computation, baseLen, expLen, modLen: Uint256, fork: Fork): GasInt =
template data: untyped {.dirty.} =
c.msg.data
func mulComplexity(x: Uint256): Uint256 =
## Estimates the difficulty of Karatsuba multiplication
if x <= 64.u256: x * x
elif x <= 1024.u256: x * x div 4.u256 + 96.u256 * x - 3072.u256
else: x * x div 16.u256 + 480.u256 * x - 199680.u256
func mulComplexityEIP2565(x: Uint256): Uint256 =
# gas = ceil(x div 8) ^ 2
result = x + 7
result = result div 8
result = result * result
let adjExpLen = block:
let
baseL = baseLen.safeInt
expL = expLen.safeInt
first32 = if baseL.uint64 + expL.uint64 < high(int32).uint64 and baseL < data.len:
data.rangeToPadded2[:Uint256](96 + baseL, 95 + baseL + expL, min(expL, 32))
else:
0.u256
if expLen <= 32:
if first32.isZero(): 0.u256
else: first32.log2.u256 # highest-bit in exponent
else:
if not first32.isZero:
8.u256 * (expLen - 32.u256) + first32.log2.u256
else:
8.u256 * (expLen - 32.u256)
template gasCalc(comp, divisor: untyped): untyped =
(
max(modLen, baseLen).comp *
max(adjExpLen, 1.u256)
) div divisor
# EIP2565: modExp gas cost
let gasFee = if fork >= FkBerlin: gasCalc(mulComplexityEIP2565, GasQuadDivisorEIP2565)
else: gasCalc(mulComplexity, GasQuadDivisor)
# let gasFee = gasCalc(mulComplexity, GasQuadDivisor)
if gasFee > high(GasInt).u256:
raise newException(OutOfGas, "modExp gas overflow")
result = gasFee.truncate(GasInt)
# EIP2565: modExp gas cost
if fork >= FkBerlin and result < 200.GasInt:
result = 200.GasInt
proc modExp*(c: Computation, fork: Fork = FkByzantium) =
## Modular exponentiation precompiled contract
## Yellow Paper Appendix E
## EIP-198 - https://github.com/ethereum/EIPs/blob/master/EIPS/eip-198.md
# Parsing the data
template data: untyped {.dirty.} =
c.msg.data
let # lengths Base, Exponent, Modulus
baseL = data.rangeToPadded[:Uint256](0, 31)
expL = data.rangeToPadded[:Uint256](32, 63)
modL = data.rangeToPadded[:Uint256](64, 95)
baseLen = baseL.safeInt
expLen = expL.safeInt
modLen = modL.safeInt
let gasFee = modExpFee(c, baseL, expL, modL, fork)
c.gasMeter.consumeGas(gasFee, reason="ModExp Precompile")
if baseLen == 0 and modLen == 0:
# This is a special case where expLength can be very big.
c.output = @[]
return
let maxBytes = max(baseLen, max(expLen, modLen))
if maxBytes <= 32:
c.modExpInternal(baseLen, expLen, modLen, UInt256)
elif maxBytes <= 64:
c.modExpInternal(baseLen, expLen, modLen, StUint[512])
elif maxBytes <= 128:
c.modExpInternal(baseLen, expLen, modLen, StUint[1024])
elif maxBytes <= 256:
c.modExpInternal(baseLen, expLen, modLen, StUint[2048])
elif maxBytes <= 512:
c.modExpInternal(baseLen, expLen, modLen, StUint[4096])
elif maxBytes <= 1024:
c.modExpInternal(baseLen, expLen, modLen, StUint[8192])
else:
raise newException(EVMError, "The Nimbus VM doesn't support modular exponentiation with numbers larger than uint8192")
proc bn256ecAdd*(computation: Computation, fork: Fork = FkByzantium) =
let gasFee = if fork < FkIstanbul: GasECAdd else: GasECAddIstanbul
computation.gasMeter.consumeGas(gasFee, reason = "ecAdd Precompile")
var
input: array[128, byte]
output: array[64, byte]
# Padding data
let len = min(computation.msg.data.len, 128) - 1
input[0..len] = computation.msg.data[0..len]
var p1 = G1.getPoint(input.toOpenArray(0, 63))
var p2 = G1.getPoint(input.toOpenArray(64, 127))
var apo = (p1 + p2).toAffine()
if isSome(apo):
# we can discard here because we supply proper buffer
discard apo.get().toBytes(output)
computation.output = @output
proc bn256ecMul*(computation: Computation, fork: Fork = FkByzantium) =
let gasFee = if fork < FkIstanbul: GasECMul else: GasECMulIstanbul
computation.gasMeter.consumeGas(gasFee, reason="ecMul Precompile")
var
input: array[96, byte]
output: array[64, byte]
# Padding data
let len = min(computation.msg.data.len, 96) - 1
input[0..len] = computation.msg.data[0..len]
var p1 = G1.getPoint(input.toOpenArray(0, 63))
var fr = getFR(input.toOpenArray(64, 95))
var apo = (p1 * fr).toAffine()
if isSome(apo):
# we can discard here because we supply buffer of proper size
discard apo.get().toBytes(output)
computation.output = @output
proc bn256ecPairing*(computation: Computation, fork: Fork = FkByzantium) =
let msglen = len(computation.msg.data)
if msglen mod 192 != 0:
raise newException(ValidationError, "Invalid input length")
let numPoints = msglen div 192
let gasFee = if fork < FkIstanbul:
GasECPairingBase + numPoints * GasECPairingPerPoint
else:
GasECPairingBaseIstanbul + numPoints * GasECPairingPerPointIstanbul
computation.gasMeter.consumeGas(gasFee, reason="ecPairing Precompile")
var output: array[32, byte]
if msglen == 0:
# we can discard here because we supply buffer of proper size
discard BNU256.one().toBytes(output)
else:
# Calculate number of pairing pairs
let count = msglen div 192
# Pairing accumulator
var acc = FQ12.one()
for i in 0..<count:
let s = i * 192
# Loading AffinePoint[G1], bytes from [0..63]
var p1 = G1.getPoint(computation.msg.data.toOpenArray(s, s + 63))
# Loading AffinePoint[G2], bytes from [64..191]
var p2 = G2.getPoint(computation.msg.data.toOpenArray(s + 64, s + 191))
# Accumulate pairing result
acc = acc * pairing(p1, p2)
if acc == FQ12.one():
# we can discard here because we supply buffer of proper size
discard BNU256.one().toBytes(output)
computation.output = @output
proc blake2bf*(c: Computation) =
template input: untyped =
c.msg.data
if len(input) == blake2FInputLength:
let gasFee = GasInt(beLoad32(input, 0))
c.gasMeter.consumeGas(gasFee, reason="blake2bf Precompile")
var output: array[64, byte]
if not blake2b_F(input, output):
raise newException(ValidationError, "Blake2b F function invalid input")
else:
c.output = @output
proc blsG1Add*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 256:
raise newException(ValidationError, "blsG1Add invalid input len")
c.gasMeter.consumeGas(Bls12381G1AddGas, reason="blsG1Add Precompile")
var a, b: BLS_G1
if not a.decodePoint(input.toOpenArray(0, 127)):
raise newException(ValidationError, "blsG1Add invalid input A")
if not b.decodePoint(input.toOpenArray(128, 255)):
raise newException(ValidationError, "blsG1Add invalid input B")
a.add b
c.output = newSeq[byte](128)
if not encodePoint(a, c.output):
raise newException(ValidationError, "blsG1Add encodePoint error")
proc blsG1Mul*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 160:
raise newException(ValidationError, "blsG1Mul invalid input len")
c.gasMeter.consumeGas(Bls12381G1MulGas, reason="blsG1Mul Precompile")
var a: BLS_G1
if not a.decodePoint(input.toOpenArray(0, 127)):
raise newException(ValidationError, "blsG1Mul invalid input A")
var scalar: BLS_SCALAR
if not scalar.fromBytes(input.toOpenArray(128, 159)):
raise newException(ValidationError, "blsG1Mul invalid scalar")
a.mul(scalar)
c.output = newSeq[byte](128)
if not encodePoint(a, c.output):
raise newException(ValidationError, "blsG1Mul encodePoint error")
const
Bls12381MultiExpDiscountTable = [
1200, 888, 764, 641, 594, 547, 500, 453, 438, 423,
408, 394, 379, 364, 349, 334, 330, 326, 322, 318,
314, 310, 306, 302, 298, 294, 289, 285, 281, 277,
273, 269, 268, 266, 265, 263, 262, 260, 259, 257,
256, 254, 253, 251, 250, 248, 247, 245, 244, 242,
241, 239, 238, 236, 235, 233, 232, 231, 229, 228,
226, 225, 223, 222, 221, 220, 219, 219, 218, 217,
216, 216, 215, 214, 213, 213, 212, 211, 211, 210,
209, 208, 208, 207, 206, 205, 205, 204, 203, 202,
202, 201, 200, 199, 199, 198, 197, 196, 196, 195,
194, 193, 193, 192, 191, 191, 190, 189, 188, 188,
187, 186, 185, 185, 184, 183, 182, 182, 181, 180,
179, 179, 178, 177, 176, 176, 175, 174
]
func calcBlsMultiExpGas(K: int, gasCost: GasInt): GasInt =
# Calculate G1 point, scalar value pair length
if K == 0:
# Return 0 gas for small input length
return 0.GasInt
const dLen = Bls12381MultiExpDiscountTable.len
# Lookup discount value for G1 point, scalar value pair length
let discount = if K < dLen: Bls12381MultiExpDiscountTable[K-1]
else: Bls12381MultiExpDiscountTable[dLen-1]
# Calculate gas and return the result
result = (K * gasCost * discount) div 1000
proc blsG1MultiExp*(c: Computation) =
template input: untyped =
c.msg.data
const L = 160
if (input.len == 0) or ((input.len mod L) != 0):
raise newException(ValidationError, "blsG1MultiExp invalid input len")
let
K = input.len div L
gas = K.calcBlsMultiExpGas(Bls12381G1MulGas)
c.gasMeter.consumeGas(gas, reason="blsG1MultiExp Precompile")
var
p: BLS_G1
s: BLS_SCALAR
acc: BLS_G1
# Decode point scalar pairs
for i in 0..<K:
let off = L * i
# Decode G1 point
if not p.decodePoint(input.toOpenArray(off, off+127)):
raise newException(ValidationError, "blsG1MultiExp invalid input P")
# Decode scalar value
if not s.fromBytes(input.toOpenArray(off+128, off+159)):
raise newException(ValidationError, "blsG1MultiExp invalid scalar")
p.mul(s)
if i == 0:
acc = p
else:
acc.add(p)
c.output = newSeq[byte](128)
if not encodePoint(acc, c.output):
raise newException(ValidationError, "blsG1MuliExp encodePoint error")
proc blsG2Add*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 512:
raise newException(ValidationError, "blsG2Add invalid input len")
c.gasMeter.consumeGas(Bls12381G2AddGas, reason="blsG2Add Precompile")
var a, b: BLS_G2
if not a.decodePoint(input.toOpenArray(0, 255)):
raise newException(ValidationError, "blsG2Add invalid input A")
if not b.decodePoint(input.toOpenArray(256, 511)):
raise newException(ValidationError, "blsG2Add invalid input B")
a.add b
c.output = newSeq[byte](256)
if not encodePoint(a, c.output):
raise newException(ValidationError, "blsG2Add encodePoint error")
proc blsG2Mul*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 288:
raise newException(ValidationError, "blsG2Mul invalid input len")
c.gasMeter.consumeGas(Bls12381G2MulGas, reason="blsG2Mul Precompile")
var a: BLS_G2
if not a.decodePoint(input.toOpenArray(0, 255)):
raise newException(ValidationError, "blsG2Mul invalid input A")
var scalar: BLS_SCALAR
if not scalar.fromBytes(input.toOpenArray(256, 287)):
raise newException(ValidationError, "blsG2Mul invalid scalar")
a.mul(scalar)
c.output = newSeq[byte](256)
if not encodePoint(a, c.output):
raise newException(ValidationError, "blsG2Mul encodePoint error")
proc blsG2MultiExp*(c: Computation) =
template input: untyped =
c.msg.data
const L = 288
if (input.len == 0) or ((input.len mod L) != 0):
raise newException(ValidationError, "blsG2MultiExp invalid input len")
let
K = input.len div L
gas = K.calcBlsMultiExpGas(Bls12381G2MulGas)
c.gasMeter.consumeGas(gas, reason="blsG2MultiExp Precompile")
var
p: BLS_G2
s: BLS_SCALAR
acc: BLS_G2
# Decode point scalar pairs
for i in 0..<K:
let off = L * i
# Decode G1 point
if not p.decodePoint(input.toOpenArray(off, off+255)):
raise newException(ValidationError, "blsG2MultiExp invalid input P")
# Decode scalar value
if not s.fromBytes(input.toOpenArray(off+256, off+287)):
raise newException(ValidationError, "blsG2MultiExp invalid scalar")
p.mul(s)
if i == 0:
acc = p
else:
acc.add(p)
c.output = newSeq[byte](256)
if not encodePoint(acc, c.output):
raise newException(ValidationError, "blsG2MuliExp encodePoint error")
proc blsPairing*(c: Computation) =
template input: untyped =
c.msg.data
const L = 384
if (input.len == 0) or ((input.len mod L) != 0):
raise newException(ValidationError, "blsG2Pairing invalid input len")
let
K = input.len div L
gas = Bls12381PairingBaseGas + K.GasInt * Bls12381PairingPerPairGas
c.gasMeter.consumeGas(gas, reason="blsG2Pairing Precompile")
var
g1: BLS_G1P
g2: BLS_G2P
acc: BLS_ACC
# Decode pairs
for i in 0..<K:
let off = L * i
# Decode G1 point
if not g1.decodePoint(input.toOpenArray(off, off+127)):
raise newException(ValidationError, "blsG2Pairing invalid G1")
# Decode G2 point
if not g2.decodePoint(input.toOpenArray(off+128, off+383)):
raise newException(ValidationError, "blsG2Pairing invalid G2")
# 'point is on curve' check already done,
# Here we need to apply subgroup checks.
if not g1.subgroupCheck:
raise newException(ValidationError, "blsG2Pairing invalid G1 subgroup")
if not g2.subgroupCheck:
raise newException(ValidationError, "blsG2Pairing invalid G2 subgroup")
# Update pairing engine with G1 and G2 points
if i == 0:
acc = millerLoop(g1, g2)
else:
acc.mul(millerLoop(g1, g2))
c.output = newSeq[byte](32)
if acc.check():
c.output[^1] = 1.byte
proc blsMapG1*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 64:
raise newException(ValidationError, "blsMapG1 invalid input len")
c.gasMeter.consumeGas(Bls12381MapG1Gas, reason="blsMapG1 Precompile")
var fe: BLS_FE
if not fe.decodeFE(input):
raise newException(ValidationError, "blsMapG1 invalid field element")
let p = fe.mapFPToG1()
c.output = newSeq[byte](128)
if not encodePoint(p, c.output):
raise newException(ValidationError, "blsMapG1 encodePoint error")
proc blsMapG2*(c: Computation) =
template input: untyped =
c.msg.data
if input.len != 128:
raise newException(ValidationError, "blsMapG2 invalid input len")
c.gasMeter.consumeGas(Bls12381MapG2Gas, reason="blsMapG2 Precompile")
var fe: BLS_FE2
if not fe.decodeFE(input):
raise newException(ValidationError, "blsMapG2 invalid field element")
let p = fe.mapFPToG2()
c.output = newSeq[byte](256)
if not encodePoint(p, c.output):
raise newException(ValidationError, "blsMapG2 encodePoint error")
proc getMaxPrecompileAddr(fork: Fork): PrecompileAddresses =
if fork < FkByzantium: paIdentity
elif fork < FkIstanbul: paPairing
# EIP 2537: disabled
# reason: not included in berlin
# elif fork < FkBerlin: paBlake2bf
else: PrecompileAddresses.high
proc execPrecompiles*(computation: Computation, fork: Fork): bool {.inline.} =
for i in 0..18:
if computation.msg.codeAddress[i] != 0: return
let lb = computation.msg.codeAddress[19]
let maxPrecompileAddr = getMaxPrecompileAddr(fork)
if lb in PrecompileAddresses.low.byte .. maxPrecompileAddr.byte:
result = true
let precompile = PrecompileAddresses(lb)
trace "Call precompile", precompile = precompile, codeAddr = computation.msg.codeAddress
try:
case precompile
of paEcRecover: ecRecover(computation)
of paSha256: sha256(computation)
of paRipeMd160: ripeMd160(computation)
of paIdentity: identity(computation)
of paModExp: modExp(computation, fork)
of paEcAdd: bn256ecAdd(computation, fork)
of paEcMul: bn256ecMul(computation, fork)
of paPairing: bn256ecPairing(computation, fork)
of paBlake2bf: blake2bf(computation)
# EIP 2537: disabled
# reason: not included in berlin
# of paBlsG1Add: blsG1Add(computation)
# of paBlsG1Mul: blsG1Mul(computation)
# of paBlsG1MultiExp: blsG1MultiExp(computation)
# of paBlsG2Add: blsG2Add(computation)
# of paBlsG2Mul: blsG2Mul(computation)
# of paBlsG2MultiExp: blsG2MultiExp(computation)
# of paBlsPairing: blsPairing(computation)
# of paBlsMapG1: blsMapG1(computation)
# of paBlsMapG2: blsMapG2(computation)
except OutOfGas as e:
# cannot use setError here, cyclic dependency
computation.error = Error(info: e.msg, burnsGas: true)
except CatchableError as e:
if fork >= FKByzantium and precompile > paIdentity:
computation.error = Error(info: e.msg, burnsGas: true)
else:
# swallow any other precompiles errors
debug "execPrecompiles validation error", msg=e.msg