1 files changed, 49 insertions, 0 deletions
diff --git a/debian/patches/try-fence0002-kern-fix-loop-reading-the-time-value.patch b/debian/patches/try-fence0002-kern-fix-loop-reading-the-time-value.patch
new file mode 100644
index 0000000..4305819
--- /dev/null
+++ b/debian/patches/try-fence0002-kern-fix-loop-reading-the-time-value.patch
@@ -0,0 +1,49 @@
+From 5b02c9e8a6f5e41ed4da7f79ddee60a0d0941201 Mon Sep 17 00:00:00 2001
+From: Justus Winter <4winter@informatik.uni-hamburg.de>
+Date: Mon, 7 Sep 2015 14:37:40 +0200
+Subject: [PATCH gnumach 2/2] kern: fix loop reading the time value
+
+Previously, recent versions of gcc would hoist the loads out of the
+loop reading the time value.
+
+* kern/macros.h (access_once): New macro.
+* kern/mach_clock.c (host_get_time): Use the new macro to prevent the
+loads from being hoisted out of the loop.
+---
+ kern/mach_clock.c | 6 +++---
+ kern/macros.h     | 2 ++
+ 2 files changed, 5 insertions(+), 3 deletions(-)
+
+diff --git a/kern/mach_clock.c b/kern/mach_clock.c
+index aab7010..0757f6c 100644
+--- a/kern/mach_clock.c
++++ b/kern/mach_clock.c
+@@ -428,9 +428,9 @@ host_get_time(host, current_time)
+ 		return(KERN_INVALID_HOST);
+ 
+ 	do {
+-		current_time->seconds = mtime->seconds;
+-		current_time->microseconds = mtime->microseconds;
+-	} while (current_time->seconds != mtime->check_seconds);
++		current_time->seconds = access_once(mtime->seconds);
++		current_time->microseconds = access_once(mtime->microseconds);
++	} while (current_time->seconds != access_once(mtime->check_seconds));
+ 
+ 	return (KERN_SUCCESS);
+ }
+diff --git a/kern/macros.h b/kern/macros.h
+index 7cc579d..c2e8545 100644
+--- a/kern/macros.h
++++ b/kern/macros.h
+@@ -52,6 +52,8 @@
+ #define structof(ptr, type, member) \
+     ((type *)((char *)(ptr) - offsetof(type, member)))
+ 
++#define access_once(x)      (*(volatile typeof(x) *)&(x))
++
+ #define alignof(x)          __alignof__(x)
+ 
+ #ifndef likely
+-- 
+2.1.4
+