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Merge pull request #326 from dusk-network/single-instance-per-call
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One instance per contract function call
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Eduardo Leegwater Simões authored Feb 12, 2024
2 parents bb2f3fc + cfe6134 commit a3a669f
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Showing 4 changed files with 151 additions and 172 deletions.
3 changes: 3 additions & 0 deletions piecrust/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -13,10 +13,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

### Changed

- Change to have one instance per contract function call [#325]
- Upgrade `dusk-wasmtime` to version `17`

### Fixed

- Fix bad dereferences in caused by instance reclamation [#325]
- Fix overflow in gas limit calculation in inter-contract call

## [0.15.0] - 2024-01-24
Expand Down Expand Up @@ -357,6 +359,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
[#234]: https://github.com/dusk-network/piecrust/pull/234

<!-- ISSUES -->
[#325]: https://github.com/dusk-network/piecrust/issues/325
[#301]: https://github.com/dusk-network/piecrust/issues/313
[#301]: https://github.com/dusk-network/piecrust/issues/301
[#296]: https://github.com/dusk-network/piecrust/issues/296
Expand Down
42 changes: 19 additions & 23 deletions piecrust/src/imports.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -138,12 +138,12 @@ pub(crate) fn hq(
) -> WasmtimeResult<u32> {
let env = fenv.data_mut();

let instance = env.self_instance();
let mut instance = env.self_instance();

let name_len = name_len as usize;

check_ptr(instance, name_ofs, name_len)?;
check_arg(instance, arg_len)?;
check_ptr(&instance, name_ofs, name_len)?;
check_arg(&instance, arg_len)?;

let name = instance.with_memory(|buf| {
// performance: use a dedicated buffer here?
Expand All @@ -163,11 +163,11 @@ pub(crate) fn hd(
) -> WasmtimeResult<u32> {
let env = fenv.data_mut();

let instance = env.self_instance();
let mut instance = env.self_instance();

let name_len = name_len as usize;

check_ptr(instance, name_ofs, name_len)?;
check_ptr(&instance, name_ofs, name_len)?;

let name = instance.with_memory(|buf| {
// performance: use a dedicated buffer here?
Expand All @@ -194,13 +194,13 @@ pub(crate) fn c(
) -> WasmtimeResult<i32> {
let env = fenv.data_mut();

let instance = env.self_instance();
let mut instance = env.self_instance();

let name_len = name_len as usize;

check_ptr(instance, mod_id_ofs, CONTRACT_ID_BYTES)?;
check_ptr(instance, name_ofs, name_len)?;
check_arg(instance, arg_len)?;
check_ptr(&instance, mod_id_ofs, CONTRACT_ID_BYTES)?;
check_ptr(&instance, name_ofs, name_len)?;
check_arg(&instance, arg_len)?;

let argbuf_ofs = instance.arg_buffer_offset();

Expand All @@ -222,12 +222,8 @@ pub(crate) fn c(
&memory[mod_id_ofs..][..std::mem::size_of::<ContractId>()],
);

let callee_stack_element = env
.push_callstack(mod_id, callee_limit)
.expect("pushing to the callstack should succeed");
let callee = env
.instance(&callee_stack_element.contract_id)
.expect("callee instance should exist");
let mut callee = env.instance(mod_id)?;
env.push_callstack(mod_id, callee_limit, callee.mem_len());

callee.snap().map_err(|err| Error::MemorySnapshotFailure {
reason: None,
Expand All @@ -242,7 +238,7 @@ pub(crate) fn c(
let ret_len = callee
.call(name, arg.len() as u32, callee_limit)
.map_err(Error::normalize)?;
check_arg(callee, ret_len as u32)?;
check_arg(&callee, ret_len as u32)?;

// copy back result
callee.read_argument(&mut memory[argbuf_ofs..][..ret_len as usize]);
Expand Down Expand Up @@ -291,8 +287,8 @@ pub(crate) fn emit(

let topic_len = topic_len as usize;

check_ptr(instance, topic_ofs, topic_len)?;
check_arg(instance, arg_len)?;
check_ptr(&instance, topic_ofs, topic_len)?;
check_arg(&instance, arg_len)?;

let data = instance.with_arg_buf(|buf| {
let arg_len = arg_len as usize;
Expand Down Expand Up @@ -327,7 +323,7 @@ fn feed(mut fenv: Caller<Env>, arg_len: u32) -> WasmtimeResult<()> {
let env = fenv.data_mut();
let instance = env.self_instance();

check_arg(instance, arg_len)?;
check_arg(&instance, arg_len)?;

let data = instance.with_arg_buf(|buf| {
let arg_len = arg_len as usize;
Expand All @@ -342,7 +338,7 @@ fn hdebug(mut fenv: Caller<Env>, msg_len: u32) -> WasmtimeResult<()> {
let env = fenv.data_mut();
let instance = env.self_instance();

check_arg(instance, msg_len)?;
check_arg(&instance, msg_len)?;

Ok(instance.with_arg_buf(|buf| {
let slice = &buf[..msg_len as usize];
Expand All @@ -365,7 +361,7 @@ fn limit(fenv: Caller<Env>) -> u64 {

fn spent(fenv: Caller<Env>) -> u64 {
let env = fenv.data();
let instance = env.self_instance();
let mut instance = env.self_instance();

let limit = env.limit();
let remaining = instance.get_remaining_gas();
Expand All @@ -377,7 +373,7 @@ fn panic(fenv: Caller<Env>, arg_len: u32) -> WasmtimeResult<()> {
let env = fenv.data();
let instance = env.self_instance();

check_arg(instance, arg_len)?;
check_arg(&instance, arg_len)?;

Ok(instance.with_arg_buf(|buf| {
let slice = &buf[..arg_len as usize];
Expand All @@ -392,7 +388,7 @@ fn panic(fenv: Caller<Env>, arg_len: u32) -> WasmtimeResult<()> {
}

fn owner(fenv: Caller<Env>, mod_id_ofs: usize) -> WasmtimeResult<i32> {
check_ptr(fenv.data().self_instance(), mod_id_ofs, CONTRACT_ID_BYTES)?;
check_ptr(&fenv.data().self_instance(), mod_id_ofs, CONTRACT_ID_BYTES)?;

let env = fenv.data();

Expand Down
96 changes: 60 additions & 36 deletions piecrust/src/instance.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
// Copyright (c) DUSK NETWORK. All rights reserved.

use std::io;
use std::mem::MaybeUninit;
use std::ops::{Deref, DerefMut};

use dusk_wasmtime::{Instance, Module, Mutability, Store, ValType};
Expand All @@ -17,15 +18,47 @@ use crate::store::Memory;
use crate::Error;

pub struct WrappedInstance {
instance: Instance,
arg_buf_ofs: usize,
store: Store<Env>,
memory: Memory,
inner: *mut WrappedInstanceInner,
original: bool,
}

impl Clone for WrappedInstance {
fn clone(&self) -> Self {
Self {
inner: self.inner,
original: false,
}
}
}

impl Drop for WrappedInstance {
fn drop(&mut self) {
if self.original {
unsafe {
let _ = Box::from_raw(self.inner);
}
}
}
}

impl Deref for WrappedInstance {
type Target = WrappedInstanceInner;

fn deref(&self) -> &Self::Target {
unsafe { &*self.inner }
}
}

impl DerefMut for WrappedInstance {
fn deref_mut(&mut self) -> &mut Self::Target {
unsafe { &mut *self.inner }
}
}

pub(crate) struct Env {
self_id: ContractId,
session: Session,
instance: MaybeUninit<WrappedInstance>,
}

impl Deref for Env {
Expand All @@ -43,20 +76,8 @@ impl DerefMut for Env {
}

impl Env {
pub fn self_instance<'b>(&self) -> &'b mut WrappedInstance {
let stack_element = self
.session
.nth_from_top(0)
.expect("there should be at least one element in the call stack");
self.instance(&stack_element.contract_id)
.expect("instance should exist")
}

pub fn instance<'b>(
&self,
contract_id: &ContractId,
) -> Option<&'b mut WrappedInstance> {
self.session.instance(contract_id)
pub fn self_instance(&self) -> WrappedInstance {
unsafe { self.instance.assume_init_ref().clone() }
}

pub fn limit(&self) -> u64 {
Expand Down Expand Up @@ -94,6 +115,7 @@ impl WrappedInstance {
let env = Env {
self_id: contract_id,
session,
instance: MaybeUninit::uninit(),
};

let module =
Expand Down Expand Up @@ -177,28 +199,35 @@ impl WrappedInstance {
// A memory is no longer new after one instantiation
memory.is_new = false;

let wrapped = WrappedInstance {
let inner = WrappedInstanceInner {
store,
instance,
arg_buf_ofs,
memory,
};

Ok(wrapped)
}
let mut instance = WrappedInstance {
inner: Box::into_raw(Box::new(inner)),
original: true,
};
let instance_clone = instance.clone();

pub(crate) fn snap(&mut self) -> io::Result<()> {
self.memory.snap()?;
Ok(())
}
instance.store.data_mut().instance = MaybeUninit::new(instance_clone);

pub(crate) fn revert(&mut self) -> io::Result<()> {
self.memory.revert()?;
Ok(())
Ok(instance)
}
}

pub(crate) fn apply(&mut self) -> io::Result<()> {
self.memory.apply()?;
pub struct WrappedInstanceInner {
instance: Instance,
arg_buf_ofs: usize,
store: Store<Env>,
memory: Memory,
}

impl WrappedInstanceInner {
pub(crate) fn snap(&mut self) -> io::Result<()> {
self.memory.snap()?;
Ok(())
}

Expand Down Expand Up @@ -238,11 +267,6 @@ impl WrappedInstance {
self.memory.current_len
}

/// Sets the length of the memory.
pub(crate) fn set_len(&mut self, len: usize) {
self.memory.current_len = len;
}

pub(crate) fn with_arg_buf<F, R>(&self, f: F) -> R
where
F: FnOnce(&[u8]) -> R,
Expand Down Expand Up @@ -342,7 +366,7 @@ impl WrappedInstance {
}

fn map_call_err(
instance: &mut WrappedInstance,
instance: &mut WrappedInstanceInner,
err: dusk_wasmtime::Error,
) -> Error {
if instance.get_remaining_gas() == 0 {
Expand Down
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