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* Add assert to `StackPool::deallocate` to ensure the fiber stack given to it
  comes from the pool.
* Remove outdated comment about windows and stacks as the allocator now returns
  fiber stacks.
* Remove conditional compilation around `stack_size` in the allocators as it
  was just clutter.
This commit is contained in:
Peter Huene
2021-03-20 00:05:08 -07:00
parent f556bd18a7
commit e6dda413a4
4 changed files with 38 additions and 38 deletions
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8
crates/runtime/src/instance/allocator.rs
View File

@@ -536,19 +536,14 @@ unsafe fn initialize_vmcontext_globals(instance: &Instance) {
#[derive(Clone)]
pub struct OnDemandInstanceAllocator {
mem_creator: Option<Arc<dyn RuntimeMemoryCreator>>,
#[cfg(feature = "async")]
stack_size: usize,
}
impl OnDemandInstanceAllocator {
/// Creates a new on-demand instance allocator.
pub fn new(
mem_creator: Option<Arc<dyn RuntimeMemoryCreator>>,
#[cfg(feature = "async")] stack_size: usize,
) -> Self {
pub fn new(mem_creator: Option<Arc<dyn RuntimeMemoryCreator>>, stack_size: usize) -> Self {
Self {
mem_creator,
#[cfg(feature = "async")]
stack_size,
}
}
@@ -586,7 +581,6 @@ impl Default for OnDemandInstanceAllocator {
fn default() -> Self {
Self {
mem_creator: None,
#[cfg(feature = "async")]
stack_size: 0,
}
}

25
crates/runtime/src/instance/allocator/pooling.rs
View File

@@ -723,7 +723,6 @@ impl StackPool {
fn new(instance_limits: &InstanceLimits, stack_size: usize) -> Result<Self> {
let page_size = region::page::size();
// On Windows, don't allocate any fiber stacks as native fibers are always used
// Add a page to the stack size for the guard page when using fiber stacks
let stack_size = if stack_size == 0 {
0
@@ -800,20 +799,28 @@ impl StackPool {
}
fn deallocate(&self, stack: &wasmtime_fiber::FiberStack) {
// Remove the guard page from the size
let stack_size = self.stack_size - self.page_size;
let bottom_of_stack = unsafe { stack.top().unwrap().sub(stack_size) };
let top = stack
.top()
.expect("fiber stack not allocated from the pool") as usize;
let base = self.mapping.as_ptr() as usize;
let start_of_stack = (bottom_of_stack as usize) - self.page_size;
let len = self.mapping.len();
assert!(
top > base && top <= (base + len),
"fiber stack top pointer not in range"
);
debug_assert!(start_of_stack >= base && start_of_stack < (base + self.mapping.len()));
// Remove the guard page from the size
let stack_size = self.stack_size - self.page_size;
let bottom_of_stack = top - stack_size;
let start_of_stack = bottom_of_stack - self.page_size;
debug_assert!(start_of_stack >= base && start_of_stack < (base + len));
debug_assert!((start_of_stack - base) % self.stack_size == 0);
let index = (start_of_stack - base) / self.stack_size;
debug_assert!(index < self.max_instances);
decommit_stack_pages(bottom_of_stack, stack_size).unwrap();
decommit_stack_pages(bottom_of_stack as _, stack_size).unwrap();
self.free_list.lock().unwrap().push(index);
}
@@ -833,7 +840,6 @@ pub struct PoolingInstanceAllocator {
instances: mem::ManuallyDrop<InstancePool>,
#[cfg(all(feature = "async", unix))]
stacks: StackPool,
#[cfg(all(feature = "async", windows))]
stack_size: usize,
#[cfg(all(feature = "uffd", target_os = "linux"))]
_fault_handler: imp::PageFaultHandler,
@@ -845,7 +851,7 @@ impl PoolingInstanceAllocator {
strategy: PoolingAllocationStrategy,
module_limits: ModuleLimits,
mut instance_limits: InstanceLimits,
#[cfg(feature = "async")] stack_size: usize,
stack_size: usize,
) -> Result<Self> {
if instance_limits.count == 0 {
bail!("the instance count limit cannot be zero");
@@ -874,7 +880,6 @@ impl PoolingInstanceAllocator {
instances: mem::ManuallyDrop::new(instances),
#[cfg(all(feature = "async", unix))]
stacks: StackPool::new(&instance_limits, stack_size)?,
#[cfg(all(feature = "async", windows))]
stack_size,
#[cfg(all(feature = "uffd", target_os = "linux"))]
_fault_handler,