tokio: limit taskdumps to specific, blessed platforms

Taskdumps depend on backtrace-rs, whose unwinding behavior is
platform-dependent. Taskdumps should not be enabled on a platform
without first assessing and mitigating platform-dependent behavior.

ref: https://github.com/tokio-rs/tokio/pull/5608/files#r1162746834

Author: jswrenn

examples/dump.rs

@@ -1,6 +1,10 @@
 //! This example demonstrates tokio's experimental taskdumping functionality.
 
-#[cfg(all(tokio_unstable, target_os = "linux"))]
+#[cfg(all(
+    tokio_unstable,
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+))]
 #[tokio::main(flavor = "current_thread")]
 async fn main() {
     use std::hint::black_box;
@@ -34,7 +38,11 @@ async fn main() {
     }
 }
 
-#[cfg(not(all(tokio_unstable, target_os = "linux")))]
+#[cfg(not(all(
+    tokio_unstable,
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+)))]
 fn main() {
     println!("task dumps are not available")
 }

tokio/src/macros/cfg.rs

@@ -376,8 +376,26 @@ macro_rules! cfg_not_rt_multi_thread {
 macro_rules! cfg_taskdump {
     ($($item:item)*) => {
         $(
-            #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
-            #[cfg_attr(docsrs, doc(cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))))]
+            #[cfg(all(
+                tokio_unstable,
+                feature = "taskdump",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "i686",
+                    target_arch = "x86_64"
+                )
+            ))]
+            #[cfg_attr(docsrs, doc(cfg(all(
+                tokio_unstable,
+                feature = "taskdump",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "i686",
+                    target_arch = "x86_64"
+                )
+            ))))]
             $item
         )*
     };

tokio/src/runtime/context.rs

@@ -50,7 +50,12 @@ struct Context {
     /// the sheduler
     budget: Cell<coop::Budget>,
 
-    #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+    #[cfg(all(
+        tokio_unstable,
+        feature = "taskdump",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+    ))]
     trace: trace::Context,
 }
 
@@ -83,7 +88,16 @@ tokio_thread_local! {
 
             budget: Cell::new(coop::Budget::unconstrained()),
 
-            #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+            #[cfg(all(
+                tokio_unstable,
+                feature = "taskdump",
+                target_os = "linux",
+                any(
+                    target_arch = "aarch64",
+                    target_arch = "i686",
+                    target_arch = "x86_64"
+                )
+            ))]
             trace: trace::Context::new(),
         }
     }

tokio/src/runtime/handle.rs

@@ -252,7 +252,12 @@ impl Handle {
     /// [`tokio::time`]: crate::time
     #[track_caller]
     pub fn block_on<F: Future>(&self, future: F) -> F::Output {
-        #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+        #[cfg(all(
+            tokio_unstable,
+            feature = "taskdump",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+        ))]
         let future = super::task::trace::Trace::root(future);
 
         #[cfg(all(tokio_unstable, feature = "tracing"))]
@@ -277,7 +282,12 @@ impl Handle {
         F::Output: Send + 'static,
     {
         let id = crate::runtime::task::Id::next();
-        #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+        #[cfg(all(
+            tokio_unstable,
+            feature = "taskdump",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+        ))]
         let future = super::task::trace::Trace::root(future);
         #[cfg(all(tokio_unstable, feature = "tracing"))]
         let future = crate::util::trace::task(future, "task", _name, id.as_u64());

tokio/src/runtime/runtime.rs

@@ -288,7 +288,12 @@ impl Runtime {
     /// [handle]: fn@Handle::block_on
     #[track_caller]
     pub fn block_on<F: Future>(&self, future: F) -> F::Output {
-        #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+        #[cfg(all(
+            tokio_unstable,
+            feature = "taskdump",
+            target_os = "linux",
+            any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+        ))]
         let future = super::task::trace::Trace::root(future);
 
         #[cfg(all(tokio_unstable, feature = "tracing"))]

tokio/src/runtime/scheduler/current_thread.rs

@@ -378,7 +378,12 @@ impl Handle {
     }
 
     /// Capture a snapshot of this runtime's state.
-    #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+    #[cfg(all(
+        tokio_unstable,
+        feature = "taskdump",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+    ))]
     pub(crate) fn dump(&self) -> crate::runtime::Dump {
         use crate::runtime::dump;
         use task::trace::trace_current_thread;

tokio/src/runtime/task/mod.rs

@@ -344,7 +344,12 @@ impl<S: 'static> Task<S> {
         }
     }
 
-    #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+    #[cfg(all(
+        tokio_unstable,
+        feature = "taskdump",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+    ))]
     pub(crate) fn as_raw(&self) -> RawTask {
         self.raw
     }

tokio/src/runtime/task/state.rs

@@ -271,7 +271,12 @@ impl State {
     }
 
     /// Transitions the state to `NOTIFIED`, unconditionally increasing the ref count.
-    #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+    #[cfg(all(
+        tokio_unstable,
+        feature = "taskdump",
+        target_os = "linux",
+        any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+    ))]
     pub(super) fn transition_to_notified_for_tracing(&self) {
         self.fetch_update_action(|mut snapshot| {
             snapshot.set_notified();

tokio/src/task/spawn.rs

@@ -179,7 +179,16 @@ cfg_rt! {
         T::Output: Send + 'static,
     {
         use crate::runtime::task;
-        #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+        #[cfg(all(
+            tokio_unstable,
+            feature = "taskdump",
+            target_os = "linux",
+            any(
+                target_arch = "aarch64",
+                target_arch = "i686",
+                target_arch = "x86_64"
+            )
+        ))]
         let future = task::trace::Trace::root(future);
         let id = task::Id::next();
         let task = crate::util::trace::task(future, "task", name, id.as_u64());

tokio/src/task/yield_now.rs

@@ -46,7 +46,12 @@ pub async fn yield_now() {
         type Output = ();
 
         fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
-            #[cfg(all(tokio_unstable, feature = "taskdump", target_os = "linux"))]
+            #[cfg(all(
+                tokio_unstable,
+                feature = "taskdump",
+                target_os = "linux",
+                any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+            ))]
             crate::runtime::task::trace::Trace::leaf();
 
             if self.yielded {

tokio/tests/dump_current_thread.rs

@@ -1,4 +1,9 @@
-#![cfg(all(feature = "taskdump", tokio_unstable, target_os = "linux"))]
+#![cfg(all(
+    tokio_unstable,
+    feature = "taskdump",
+    target_os = "linux",
+    any(target_arch = "aarch64", target_arch = "i686", target_arch = "x86_64")
+))]
 
 use std::hint::black_box;
 use tokio::runtime;