From bee530b7b140b509ed0f6eee6dd7611a8460f83e Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Fri, 4 Mar 2022 14:46:14 +0000
Subject: [PATCH] Don't try generating a backtrace on stack overflow

---
 lib/vm/src/trap/traphandlers.rs | 18 +++++++++++++++---
 tests/compilers/traps.rs        | 10 +++-------
 tests/ignores.txt               |  6 ------
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/lib/vm/src/trap/traphandlers.rs b/lib/vm/src/trap/traphandlers.rs
index 58736a94de7..7fd6db45182 100644
--- a/lib/vm/src/trap/traphandlers.rs
+++ b/lib/vm/src/trap/traphandlers.rs
@@ -715,9 +715,6 @@ impl<T> TrapHandlerContextInner<T> {
             return false;
         }
 
-        // Set up the register state for exception return to force the
-        // coroutine to return to its caller with UnwindReason::WasmTrap.
-        let backtrace = Backtrace::new_unresolved();
         let signal_trap = maybe_fault_address.map(|addr| {
             if self.coro_trap_handler.stack_ptr_in_bounds(addr) {
                 TrapCode::StackOverflow
@@ -725,6 +722,21 @@ impl<T> TrapHandlerContextInner<T> {
                 TrapCode::HeapAccessOutOfBounds
             }
         });
+
+        // Don't try to generate a backtrace for stack overflows: unwinding
+        // information is often not precise enough to properly describe what is
+        // happenning during a function prologue, which can lead the unwinder to
+        // read invalid memory addresses.
+        //
+        // See: https://github.com/rust-lang/backtrace-rs/pull/357
+        let backtrace = if signal_trap == Some(TrapCode::StackOverflow) {
+            Backtrace::from(vec![])
+        } else {
+            Backtrace::new_unresolved()
+        };
+
+        // Set up the register state for exception return to force the
+        // coroutine to return to its caller with UnwindReason::WasmTrap.
         let unwind = UnwindReason::WasmTrap {
             backtrace,
             signal_trap,
diff --git a/tests/compilers/traps.rs b/tests/compilers/traps.rs
index 493090c7e9a..77b5d6e8560 100644
--- a/tests/compilers/traps.rs
+++ b/tests/compilers/traps.rs
@@ -135,13 +135,9 @@ fn test_trap_stack_overflow(config: crate::Config) -> Result<()> {
 
     let e = run_func.call(&[]).err().expect("error calling function");
 
-    let trace = e.trace();
-    assert!(trace.len() >= 32);
-    for i in 0..trace.len() {
-        assert_eq!(trace[i].module_name(), "rec_mod");
-        assert_eq!(trace[i].func_index(), 0);
-        assert_eq!(trace[i].function_name(), Some("run"));
-    }
+    // We specifically don't check the stack trace here: stack traces after
+    // stack overflows are not generally possible due to unreliable unwinding
+    // information.
     assert!(e.message().contains("call stack exhausted"));
 
     Ok(())
diff --git a/tests/ignores.txt b/tests/ignores.txt
index ba4976b9a03..a7b67a9a6d3 100644
--- a/tests/ignores.txt
+++ b/tests/ignores.txt
@@ -36,16 +36,10 @@ aarch64    traps::start_trap_pretty
 singlepass multi_value_imports::dylib # Singlepass doesn't support multivalue
 singlepass multi_value_imports::dynamic # Singlepass doesn't support multivalue
 
-# TODO: We need to fix this in ARM. The issue is caused by libunwind overflowing
-# the stack while creating the stacktrace.
-# https://github.com/rust-lang/backtrace-rs/issues/356
 # Also neither LLVM nor Cranelift currently implement stack probing on AArch64.
 # https://github.com/wasmerio/wasmer/issues/2808
 cranelift+aarch64 spec::skip_stack_guard_page
 llvm+aarch64      spec::skip_stack_guard_page
-# TODO: Needs more investigation
-cranelift+macos spec::skip_stack_guard_page
-llvm+macos spec::skip_stack_guard_page
 
 # Some SIMD opperations are not yet supported by Cranelift
 # Cranelift just added support for most of those recently, it might be easy to update