From dcded84feb79c38a69ff63c65e86862194323f51 Mon Sep 17 00:00:00 2001
From: Johnathan Sharratt <johnathan.sharratt@gmail.com>
Date: Sun, 26 May 2024 11:09:23 +1000
Subject: [PATCH] Only warn on stack pointers if needed

---
 lib/wasix/src/state/env.rs      | 15 +++++++++++++++
 lib/wasix/src/state/func_env.rs | 15 ++++++++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/wasix/src/state/env.rs b/lib/wasix/src/state/env.rs
index a626aa09236..e69df00ece6 100644
--- a/lib/wasix/src/state/env.rs
+++ b/lib/wasix/src/state/env.rs
@@ -95,6 +95,10 @@ pub struct WasiInstanceHandles {
     /// when a CTRL-C is pressed.
     pub(crate) signal_set: bool,
 
+    /// Flag that indicates if the stack capture exports are being used by
+    /// this WASM process which means that it will be using asyncify
+    pub(crate) has_stack_checkpoint: bool,
+
     /// asyncify_start_unwind(data : i32): call this to start unwinding the
     /// stack from the current location. "data" must point to a data
     /// structure as described above (with fields containing valid data).
@@ -143,6 +147,10 @@ pub struct WasiInstanceHandles {
 
 impl WasiInstanceHandles {
     pub fn new(memory: Memory, store: &impl AsStoreRef, instance: Instance) -> Self {
+        let has_stack_checkpoint = instance
+            .module()
+            .imports()
+            .any(|f| f.name() == "stack_checkpoint");
         WasiInstanceHandles {
             memory,
             stack_pointer: instance
@@ -178,6 +186,7 @@ impl WasiInstanceHandles {
                 .exports
                 .get_typed_function(&store, "__wasm_signal")
                 .ok(),
+            has_stack_checkpoint,
             signal_set: false,
             asyncify_start_unwind: instance
                 .exports
@@ -439,6 +448,12 @@ impl WasiEnv {
         self.thread.tid()
     }
 
+    /// Returns true if this WASM process will need and try to use
+    /// asyncify while its running which normally means.
+    pub fn will_use_asyncify(&self) -> bool {
+        self.enable_deep_sleep || unsafe { self.inner().has_stack_checkpoint }
+    }
+
     /// Re-initializes this environment so that it can be executed again
     pub fn reinit(&mut self) -> Result<(), WasiStateCreationError> {
         // If the cleanup logic is enabled then we need to rebuild the
diff --git a/lib/wasix/src/state/func_env.rs b/lib/wasix/src/state/func_env.rs
index 0934c95ec41..29f1c6d5464 100644
--- a/lib/wasix/src/state/func_env.rs
+++ b/lib/wasix/src/state/func_env.rs
@@ -148,6 +148,7 @@ impl WasiFunctionEnv {
         )?;
 
         let new_inner = WasiInstanceHandles::new(memory, store, instance);
+
         let stack_pointer = new_inner.stack_pointer.clone();
         let data_end = new_inner.data_end.clone();
         let stack_low = new_inner.stack_low.clone();
@@ -199,15 +200,19 @@ impl WasiFunctionEnv {
                 // clang-16 and higher generate the `__stack_low` global, and it can be exported with
                 // `-Wl,--export=__stack_low`. clang-15 generates `__data_end`, which should be identical
                 // and can be exported if `__stack_low` is not available.
-                tracing::warn!("Missing both __stack_low and __data_end exports, unwinding may cause memory corruption");
+                if self.data(store).will_use_asyncify() {
+                    tracing::warn!("Missing both __stack_low and __data_end exports, unwinding may cause memory corruption");
+                }
                 0
             };
 
             if stack_lower >= stack_base {
-                tracing::warn!(
-                    "Detected lower end of stack to be above higher end, ignoring stack_lower; \
-                    unwinding may cause memory corruption"
-                );
+                if self.data(store).will_use_asyncify() {
+                    tracing::warn!(
+                        "Detected lower end of stack to be above higher end, ignoring stack_lower; \
+                        unwinding may cause memory corruption"
+                    );
+                }
                 stack_lower = 0;
             }