Unwind mutex workaround

include/ccf/pal/locking.h

@@ -11,62 +11,17 @@
 
 namespace ccf::pal
 {
-#if !defined(INSIDE_ENCLAVE) || defined(VIRTUAL_ENCLAVE)
-
   /**
    * Virtual enclaves and the host code share the same PAL.
-   * This PAL takes no dependence on OpenEnclave, but also does not apply
-   * security hardening.
    */
   using Mutex = std::mutex;
 
+#if !defined(INSIDE_ENCLAVE) || defined(VIRTUAL_ENCLAVE)
   static inline void speculation_barrier() {}
-
 #else
-
-  /**
-   * Temporary workaround until the fix for
-   * https://github.com/openenclave/openenclave/issues/4555 is available in a
-   * release.
-   */
-  class MutexImpl
-  {
-  private:
-    pthread_spinlock_t sl;
-
-  public:
-    MutexImpl()
-    {
-      pthread_spin_init(&sl, PTHREAD_PROCESS_PRIVATE);
-    }
-
-    ~MutexImpl()
-    {
-      pthread_spin_destroy(&sl);
-    }
-
-    void lock()
-    {
-      pthread_spin_lock(&sl);
-    }
-
-    bool try_lock()
-    {
-      return pthread_spin_trylock(&sl) == 0;
-    }
-
-    void unlock()
-    {
-      pthread_spin_unlock(&sl);
-    }
-  };
-
-  using Mutex = MutexImpl;
-
   static inline void speculation_barrier()
   {
     oe_lfence();
   }
-
 #endif
 }