kernel - cpu_pause() needs to be memory-modifying

* __asm __volatile isn't enough, it also needs the "memory"
  attribute to prevent gcc from optimizing out memory loads around
  loops using cpu_pause().

diff --git a/sys/cpu/i386/include/cpufunc.h b/sys/cpu/i386/include/cpufunc.h
index 309d6ca..ee321ab 100644 (file)
--- a/sys/cpu/i386/include/cpufunc.h
+++ b/sys/cpu/i386/include/cpufunc.h
@@ -75,7 +75,7 @@ breakpoint(void)
 static __inline void
 cpu_pause(void)
 {
-       __asm __volatile("pause");
+       __asm __volatile("pause":::"memory");
 }
 
 /*

diff --git a/sys/cpu/x86_64/include/cpufunc.h b/sys/cpu/x86_64/include/cpufunc.h
index cd79b0d..8d04a76 100644 (file)
--- a/sys/cpu/x86_64/include/cpufunc.h
+++ b/sys/cpu/x86_64/include/cpufunc.h
@@ -76,7 +76,7 @@ breakpoint(void)
 static __inline void
 cpu_pause(void)
 {
-       __asm __volatile("pause");
+       __asm __volatile("pause":::"memory");
 }
 
 static __inline u_int