From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 8 Jun 2011 21:33:14 +0000 (-0400)
Subject: Add field alignment support
X-Git-Tag: v2.0-pre1~58
X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=6c29ebe78ae39a3eaf707aec5ad0988df0e13ca4

Add field alignment support

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/lib/align.h b/lib/align.h
new file mode 100644
index 00000000..0b861000
--- /dev/null
+++ b/lib/align.h
@@ -0,0 +1,61 @@
+#ifndef _LTTNG_ALIGN_H
+#define _LTTNG_ALIGN_H
+
+/*
+ * lib/align.h
+ *
+ * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include "bug.h"
+
+#define ALIGN_FLOOR(x, a)	__ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
+#define __ALIGN_FLOOR_MASK(x, mask)	((x) & ~(mask))
+#define PTR_ALIGN_FLOOR(p, a) \
+			((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
+
+/*
+ * Align pointer on natural object alignment.
+ */
+#define object_align(obj)	PTR_ALIGN(obj, __alignof__(*(obj)))
+#define object_align_floor(obj)	PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
+
+/**
+ * offset_align - Calculate the offset needed to align an object on its natural
+ *                alignment towards higher addresses.
+ * @align_drift:  object offset from an "alignment"-aligned address.
+ * @alignment:    natural object alignment. Must be non-zero, power of 2.
+ *
+ * Returns the offset that must be added to align towards higher
+ * addresses.
+ */
+#define offset_align(align_drift, alignment)				       \
+	({								       \
+		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \
+				   || ((alignment) & ((alignment) - 1)));      \
+		(((alignment) - (align_drift)) & ((alignment) - 1));	       \
+	})
+
+/**
+ * offset_align_floor - Calculate the offset needed to align an object
+ *                      on its natural alignment towards lower addresses.
+ * @align_drift:  object offset from an "alignment"-aligned address.
+ * @alignment:    natural object alignment. Must be non-zero, power of 2.
+ *
+ * Returns the offset that must be substracted to align towards lower addresses.
+ */
+#define offset_align_floor(align_drift, alignment)			       \
+	({								       \
+		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \
+				   || ((alignment) & ((alignment) - 1)));      \
+		(((align_drift) - (alignment)) & ((alignment) - 1);	       \
+	})
+
+#endif /* __KERNEL__ */
+
+#endif
diff --git a/lib/ringbuffer/config.h b/lib/ringbuffer/config.h
index 770f692c..fd73d551 100644
--- a/lib/ringbuffer/config.h
+++ b/lib/ringbuffer/config.h
@@ -14,6 +14,7 @@
 
 #include <linux/types.h>
 #include <linux/percpu.h>
+#include "../align.h"
 
 struct lib_ring_buffer;
 struct channel;
diff --git a/ltt-tracer-core.h b/ltt-tracer-core.h
index d464877d..4357cec3 100644
--- a/ltt-tracer-core.h
+++ b/ltt-tracer-core.h
@@ -14,7 +14,7 @@
 #include <linux/list.h>
 #include <linux/percpu.h>
 
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+#if 1 //ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 /* Align data on its natural alignment */
 #define RING_BUFFER_ALIGN
 #endif