Tweak some comments

crates/runtime/src/traphandlers.rs

@@ -486,10 +486,13 @@ impl CallThreadState {
     ///
     /// For more information about interrupts and stack limits see
     /// `crates/environ/src/cranelift.rs`.
+    ///
+    /// Note that this function must be called with `self` on the stack, not the
+    /// heap/etc.
     fn update_stack_limit(&self, max_wasm_stack: usize) -> Result<impl Drop + '_, Trap> {
         // Make an "educated guess" to figure out where the wasm sp value should
         // start trapping if it drops below.
-        let wasm_stack_limit = &self as *const _ as usize - max_wasm_stack;
+        let wasm_stack_limit = self as *const _ as usize - max_wasm_stack;
 
         let interrupts = unsafe { &**(&*self.vmctx).instance().interrupts() };
         let reset_stack_limit = match interrupts.stack_limit.compare_exchange(
@@ -499,8 +502,8 @@ impl CallThreadState {
             SeqCst,
         ) {
             Ok(_) => {
-                // We're the first wasm on the stack so we've now reserved
-                // the `WASM_STACK` bytes of native stack space for wasm.
+                // We're the first wasm on the stack so we've now reserved the
+                // `max_wasm_stack` bytes of native stack space for wasm.
                 // Nothing left to do here now except reset back when we're
                 // done.
                 true