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Refactor shared memory internals, expose embedder methods #5311

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merged 1 commit into from
Nov 22, 2022
Merged

Refactor shared memory internals, expose embedder methods #5311

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4 changes: 2 additions & 2 deletions crates/runtime/src/instance.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -966,8 +966,8 @@ impl Instance {
let def_ptr = self.memories[defined_memory_index]
.as_shared_memory()
.unwrap()
.vmmemory_ptr_mut();
ptr::write(ptr, def_ptr);
.vmmemory_ptr();
ptr::write(ptr, def_ptr.cast_mut());
} else {
ptr::write(owned_ptr, self.memories[defined_memory_index].vmmemory());
ptr::write(ptr, owned_ptr);
Expand Down
14 changes: 14 additions & 0 deletions crates/runtime/src/lib.rs
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Expand Up @@ -231,3 +231,17 @@ pub fn page_size() -> usize {
unsafe { libc::sysconf(libc::_SC_PAGESIZE) as usize }
}
}

/// Result of [`Memory::atomic_wait32`] and [`Memory::atomic_wait64`]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum WaitResult {
/// Indicates that a `wait` completed by being awoken by a different thread.
/// This means the thread went to sleep and didn't time out.
Ok = 0,
/// Indicates that `wait` did not complete and instead returned due to the
/// value in memory not matching the expected value.
Mismatch = 1,
/// Indicates that `wait` completed with a timeout, meaning that the
/// original value matched as expected but nothing ever called `notify`.
TimedOut = 2,
}
53 changes: 10 additions & 43 deletions crates/runtime/src/libcalls.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@
use crate::externref::VMExternRef;
use crate::table::{Table, TableElementType};
use crate::vmcontext::{VMCallerCheckedAnyfunc, VMContext};
use crate::{SharedMemory, TrapReason};
use crate::TrapReason;
use anyhow::Result;
use std::mem;
use std::ptr::{self, NonNull};
Expand Down Expand Up @@ -436,25 +436,12 @@ unsafe fn memory_atomic_notify(
memory_index: u32,
addr_index: u64,
count: u32,
) -> Result<u32, TrapReason> {
) -> Result<u32, Trap> {
let memory = MemoryIndex::from_u32(memory_index);
let instance = (*vmctx).instance_mut();
instance
.get_memory(memory)
.validate_addr(addr_index, 4, 4)?;

let shared_mem = instance.get_runtime_memory(memory).as_shared_memory();

if count == 0 {
return Ok(0);
}

let unparked_threads = shared_mem.map_or(0, |shared_mem| {
// SAFETY: checked `addr_index` above
unsafe { shared_mem.unchecked_atomic_notify(addr_index, count) }
});

Ok(unparked_threads)
.get_runtime_memory(memory)
.atomic_notify(addr_index, count)
}

// Implementation of `memory.atomic.wait32` for locally defined memories.
Expand All @@ -464,24 +451,14 @@ unsafe fn memory_atomic_wait32(
addr_index: u64,
expected: u32,
timeout: u64,
) -> Result<u32, TrapReason> {
) -> Result<u32, Trap> {
// convert timeout to Instant, before any wait happens on locking
let timeout = (timeout as i64 >= 0).then(|| Instant::now() + Duration::from_nanos(timeout));

let memory = MemoryIndex::from_u32(memory_index);
let instance = (*vmctx).instance_mut();
let addr = instance
.get_memory(memory)
.validate_addr(addr_index, 4, 4)?;

let shared_mem: SharedMemory = instance
Ok(instance
.get_runtime_memory(memory)
.as_shared_memory()
.ok_or(Trap::AtomicWaitNonSharedMemory)?;

// SAFETY: checked `addr_index` above
let res = unsafe { shared_mem.unchecked_atomic_wait32(addr_index, addr, expected, timeout) };
Ok(res)
.atomic_wait32(addr_index, expected, timeout)? as u32)
}

// Implementation of `memory.atomic.wait64` for locally defined memories.
Expand All @@ -491,24 +468,14 @@ unsafe fn memory_atomic_wait64(
addr_index: u64,
expected: u64,
timeout: u64,
) -> Result<u32, TrapReason> {
) -> Result<u32, Trap> {
// convert timeout to Instant, before any wait happens on locking
let timeout = (timeout as i64 >= 0).then(|| Instant::now() + Duration::from_nanos(timeout));

let memory = MemoryIndex::from_u32(memory_index);
let instance = (*vmctx).instance_mut();
let addr = instance
.get_memory(memory)
.validate_addr(addr_index, 8, 8)?;

let shared_mem: SharedMemory = instance
Ok(instance
.get_runtime_memory(memory)
.as_shared_memory()
.ok_or(Trap::AtomicWaitNonSharedMemory)?;

// SAFETY: checked `addr_index` above
let res = unsafe { shared_mem.unchecked_atomic_wait64(addr_index, addr, expected, timeout) };
Ok(res)
.atomic_wait64(addr_index, expected, timeout)? as u32)
}

// Hook for when an instance runs out of fuel.
Expand Down
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