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VM Storage Cache #209

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1 change: 1 addition & 0 deletions .dockerignore
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ arbitrator/wasm-testsuite/target/
arbitrator/wasm-libraries/target/
arbitrator/tools/wasmer/target/
arbitrator/tools/wasm-tools/
arbitrator/tools/pricers/
arbitrator/tools/module_roots/
arbitrator/langs/rust/target/
arbitrator/langs/bf/target/
Expand Down
1 change: 1 addition & 0 deletions arbitrator/Cargo.lock

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1 change: 1 addition & 0 deletions arbitrator/Cargo.toml
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
[workspace]
members = [
"arbutil",
"caller-env",
"prover",
"stylus",
"jit",
Expand Down
1 change: 1 addition & 0 deletions arbitrator/arbutil/Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ edition = "2021"
[dependencies]
digest = "0.9.0"
eyre = "0.6.5"
fnv = "1.0.7"
hex = "0.4.3"
num-traits = "0.2.17"
siphasher = "0.3.10"
Expand Down
31 changes: 15 additions & 16 deletions arbitrator/arbutil/src/evm/api.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,28 +3,24 @@

use crate::{evm::user::UserOutcomeKind, Bytes20, Bytes32};
use eyre::Result;
use num_enum::IntoPrimitive;
use std::sync::Arc;

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[derive(Clone, Copy, Debug, PartialEq, Eq, IntoPrimitive)]
#[repr(u8)]
pub enum EvmApiStatus {
Success,
Failure,
}

impl From<EvmApiStatus> for UserOutcomeKind {
fn from(value: EvmApiStatus) -> Self {
match value {
EvmApiStatus::Success => UserOutcomeKind::Success,
EvmApiStatus::Failure => UserOutcomeKind::Revert,
}
}
OutOfGas,
WriteProtection,
}

impl From<u8> for EvmApiStatus {
fn from(value: u8) -> Self {
match value {
0 => Self::Success,
2 => Self::OutOfGas,
3 => Self::WriteProtection,
_ => Self::Failure,
}
}
Expand All @@ -34,7 +30,7 @@ impl From<u8> for EvmApiStatus {
#[repr(u32)]
pub enum EvmApiMethod {
GetBytes32,
SetBytes32,
SetTrieSlots,
ContractCall,
DelegateCall,
StaticCall,
Expand Down Expand Up @@ -81,10 +77,13 @@ pub trait EvmApi<D: DataReader>: Send + 'static {
/// Analogous to `vm.SLOAD`.
fn get_bytes32(&mut self, key: Bytes32) -> (Bytes32, u64);

/// Stores the given value at the given key in the EVM state trie.
/// Returns the access cost on success.
/// Analogous to `vm.SSTORE`.
fn set_bytes32(&mut self, key: Bytes32, value: Bytes32) -> Result<u64>;
/// Stores the given value at the given key in Stylus VM's cache of the EVM state trie.
/// Note that the actual values only get written after calls to `set_trie_slots`.
fn cache_bytes32(&mut self, key: Bytes32, value: Bytes32) -> u64;

/// Persists any dirty values in the storage cache to the EVM state trie, dropping the cache entirely if requested.
/// Analogous to repeated invocations of `vm.SSTORE`.
fn flush_storage_cache(&mut self, clear: bool, gas_left: u64) -> Result<u64>;

/// Calls the contract at the given address.
/// Returns the EVM return data's length, the gas cost, and whether the call succeeded.
Expand Down Expand Up @@ -141,7 +140,7 @@ pub trait EvmApi<D: DataReader>: Send + 'static {
) -> (eyre::Result<Bytes20>, u32, u64);

/// Returns the EVM return data.
/// Analogous to `vm.RETURNDATASIZE`.
/// Analogous to `vm.RETURNDATA`.
fn get_return_data(&self) -> D;

/// Emits an EVM log with the given number of topics and data, the first bytes of which should be the topic data.
Expand Down
6 changes: 5 additions & 1 deletion arbitrator/arbutil/src/evm/mod.rs
Original file line number Diff line number Diff line change
@@ -1,10 +1,11 @@
// Copyright 2023, Offchain Labs, Inc.
// Copyright 2023-2024, Offchain Labs, Inc.
// For license information, see https://github.com/OffchainLabs/nitro/blob/master/LICENSE

use crate::{Bytes20, Bytes32};

pub mod api;
pub mod req;
pub mod storage;
pub mod user;

// params.SstoreSentryGasEIP2200
Expand All @@ -16,6 +17,9 @@ pub const COLD_ACCOUNT_GAS: u64 = 2600;
// params.ColdSloadCostEIP2929
pub const COLD_SLOAD_GAS: u64 = 2100;

// params.WarmStorageReadCostEIP2929
pub const WARM_SLOAD_GAS: u64 = 100;

// params.LogGas and params.LogDataGas
pub const LOG_TOPIC_GAS: u64 = 375;
pub const LOG_DATA_GAS: u64 = 8;
Expand Down
81 changes: 57 additions & 24 deletions arbitrator/arbutil/src/evm/req.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,21 +3,26 @@

use crate::{
evm::{
api::{DataReader, EvmApi, EvmApiMethod},
api::{DataReader, EvmApi, EvmApiMethod, EvmApiStatus},
storage::{StorageCache, StorageWord},
user::UserOutcomeKind,
},
format::Utf8OrHex,
pricing::EVM_API_INK,
Bytes20, Bytes32,
};
use eyre::{bail, eyre, Result};
use std::collections::hash_map::Entry;

pub trait RequestHandler<D: DataReader>: Send + 'static {
fn handle_request(&mut self, req_type: EvmApiMethod, req_data: &[u8]) -> (Vec<u8>, D, u64);
fn request(&mut self, req_type: EvmApiMethod, req_data: impl AsRef<[u8]>) -> (Vec<u8>, D, u64);
}

pub struct EvmApiRequestor<D: DataReader, H: RequestHandler<D>> {
handler: H,
last_code: Option<(Bytes20, D)>,
last_return_data: Option<D>,
storage_cache: StorageCache,
}

impl<D: DataReader, H: RequestHandler<D>> EvmApiRequestor<D, H> {
Expand All @@ -26,11 +31,12 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApiRequestor<D, H> {
handler,
last_code: None,
last_return_data: None,
storage_cache: StorageCache::default(),
}
}

fn handle_request(&mut self, req_type: EvmApiMethod, req_data: &[u8]) -> (Vec<u8>, D, u64) {
self.handler.handle_request(req_type, req_data)
fn request(&mut self, req_type: EvmApiMethod, req_data: impl AsRef<[u8]>) -> (Vec<u8>, D, u64) {
self.handler.request(req_type, req_data)
}

/// Call out to a contract.
Expand All @@ -48,7 +54,7 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApiRequestor<D, H> {
request.extend(gas.to_be_bytes());
request.extend(input);

let (res, data, cost) = self.handle_request(call_type, &request);
let (res, data, cost) = self.request(call_type, &request);
let status: UserOutcomeKind = res[0].try_into().expect("unknown outcome");
let data_len = data.slice().len() as u32;
self.last_return_data = Some(data);
Expand All @@ -75,7 +81,7 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApiRequestor<D, H> {
}
request.extend(code);

let (mut res, data, cost) = self.handle_request(create_type, &request);
let (mut res, data, cost) = self.request(create_type, request);
if res.len() != 21 || res[0] == 0 {
if !res.is_empty() {
res.remove(0);
Expand All @@ -93,20 +99,47 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApiRequestor<D, H> {

impl<D: DataReader, H: RequestHandler<D>> EvmApi<D> for EvmApiRequestor<D, H> {
fn get_bytes32(&mut self, key: Bytes32) -> (Bytes32, u64) {
let (res, _, cost) = self.handle_request(EvmApiMethod::GetBytes32, key.as_slice());
(res.try_into().unwrap(), cost)
let cache = &mut self.storage_cache;
let mut cost = cache.read_gas();

let value = cache.entry(key).or_insert_with(|| {
let (res, _, gas) = self.handler.request(EvmApiMethod::GetBytes32, key);
cost = cost.saturating_add(gas).saturating_add(EVM_API_INK);
StorageWord::known(res.try_into().unwrap())
});
(value.value, cost)
}

fn set_bytes32(&mut self, key: Bytes32, value: Bytes32) -> Result<u64> {
let mut request = Vec::with_capacity(64);
request.extend(key);
request.extend(value);
let (res, _, cost) = self.handle_request(EvmApiMethod::SetBytes32, &request);
if res.len() != 1 {
bail!("bad response from set_bytes32")
fn cache_bytes32(&mut self, key: Bytes32, value: Bytes32) -> u64 {
let cost = self.storage_cache.write_gas();
match self.storage_cache.entry(key) {
Entry::Occupied(mut key) => key.get_mut().value = value,
Entry::Vacant(slot) => drop(slot.insert(StorageWord::unknown(value))),
};
cost
}

fn flush_storage_cache(&mut self, clear: bool, gas_left: u64) -> Result<u64> {
let mut data = Vec::with_capacity(64 * self.storage_cache.len() + 8);
data.extend(gas_left.to_be_bytes());

for (key, value) in &mut self.storage_cache.slots {
if value.dirty() {
data.extend(*key);
data.extend(*value.value);
value.known = Some(value.value);
}
}
if clear {
self.storage_cache.clear();
}
if res[0] != 1 {
bail!("write protected")
if data.len() == 8 {
return Ok(0); // no need to make request
}

let (res, _, cost) = self.request(EvmApiMethod::SetTrieSlots, data);
if res[0] != EvmApiStatus::Success.into() {
bail!("{}", String::from_utf8_or_hex(res));
}
Ok(cost)
}
Expand Down Expand Up @@ -175,19 +208,20 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApi<D> for EvmApiRequestor<D, H> {
}

fn emit_log(&mut self, data: Vec<u8>, topics: u32) -> Result<()> {
// TODO: remove copy
let mut request = Vec::with_capacity(4 + data.len());
request.extend(topics.to_be_bytes());
request.extend(data);

let (res, _, _) = self.handle_request(EvmApiMethod::EmitLog, &request);
let (res, _, _) = self.request(EvmApiMethod::EmitLog, request);
if !res.is_empty() {
bail!(String::from_utf8(res).unwrap_or("malformed emit-log response".into()))
}
Ok(())
}

fn account_balance(&mut self, address: Bytes20) -> (Bytes32, u64) {
let (res, _, cost) = self.handle_request(EvmApiMethod::AccountBalance, address.as_slice());
let (res, _, cost) = self.request(EvmApiMethod::AccountBalance, address);
(res.try_into().unwrap(), cost)
}

Expand All @@ -201,19 +235,18 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApi<D> for EvmApiRequestor<D, H> {
req.extend(address);
req.extend(gas_left.to_be_bytes());

let (_, data, cost) = self.handle_request(EvmApiMethod::AccountCode, &req);
let (_, data, cost) = self.request(EvmApiMethod::AccountCode, req);
self.last_code = Some((address, data.clone()));
(data, cost)
}

fn account_codehash(&mut self, address: Bytes20) -> (Bytes32, u64) {
let (res, _, cost) = self.handle_request(EvmApiMethod::AccountCodeHash, address.as_slice());
let (res, _, cost) = self.request(EvmApiMethod::AccountCodeHash, address);
(res.try_into().unwrap(), cost)
}

fn add_pages(&mut self, pages: u16) -> u64 {
self.handle_request(EvmApiMethod::AddPages, &pages.to_be_bytes())
.2
self.request(EvmApiMethod::AddPages, pages.to_be_bytes()).2
}

fn capture_hostio(
Expand All @@ -233,6 +266,6 @@ impl<D: DataReader, H: RequestHandler<D>> EvmApi<D> for EvmApiRequestor<D, H> {
request.extend(name.as_bytes());
request.extend(args);
request.extend(outs);
self.handle_request(EvmApiMethod::CaptureHostIO, &request);
self.request(EvmApiMethod::CaptureHostIO, request);
}
}
73 changes: 73 additions & 0 deletions arbitrator/arbutil/src/evm/storage.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,73 @@
// Copyright 2022-2024, Offchain Labs, Inc.
// For license information, see https://github.com/nitro/blob/master/LICENSE

use crate::Bytes32;
use fnv::FnvHashMap as HashMap;
use std::ops::{Deref, DerefMut};

/// Represents the EVM word at a given key.
#[derive(Debug)]
pub struct StorageWord {
/// The current value of the slot.
pub value: Bytes32,
/// The value in Geth, if known.
pub known: Option<Bytes32>,
}

impl StorageWord {
pub fn known(value: Bytes32) -> Self {
let known = Some(value);
Self { value, known }
}

pub fn unknown(value: Bytes32) -> Self {
Self { value, known: None }
}

pub fn dirty(&self) -> bool {
Some(self.value) != self.known
}
}

#[derive(Default)]
pub struct StorageCache {
pub(crate) slots: HashMap<Bytes32, StorageWord>,
reads: usize,
writes: usize,
}

impl StorageCache {
pub const REQUIRED_ACCESS_GAS: u64 = 10;

pub fn read_gas(&mut self) -> u64 {
self.reads += 1;
match self.reads {
0..=32 => 0,
33..=128 => 2,
_ => 10,
}
}

pub fn write_gas(&mut self) -> u64 {
self.writes += 1;
match self.writes {
0..=8 => 0,
9..=64 => 7,
_ => 10,
}
}
}

impl Deref for StorageCache {
type Target = HashMap<Bytes32, StorageWord>;

fn deref(&self) -> &Self::Target {
&self.slots
}
}

impl DerefMut for StorageCache {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.slots
}
}
13 changes: 13 additions & 0 deletions arbitrator/arbutil/src/format.rs
Original file line number Diff line number Diff line change
Expand Up @@ -50,3 +50,16 @@ impl<T: Debug> DebugBytes for T {
format!("{:?}", self).as_bytes().to_vec()
}
}

pub trait Utf8OrHex {
fn from_utf8_or_hex(data: impl Into<Vec<u8>>) -> String;
}

impl Utf8OrHex for String {
fn from_utf8_or_hex(data: impl Into<Vec<u8>>) -> String {
match String::from_utf8(data.into()) {
Ok(string) => string,
Err(error) => hex::encode(error.as_bytes()),
}
}
}
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