x86_64: Align uint64_t/int64_t structure member to 8 bytes
To make sure the stature which pass between 32/64bit process have
same memory layout for 32/64bit.
Signed-off-by: Fengwei Yin <fengwei.yin@intel.com>
Co-Authored-by: Narayan Kamath <narayan@google.com> (Unit test only.)
Change-Id: I1bc2d12cce41ec0bc484adcaf968f274bec75c12
diff --git a/include/input/Input.h b/include/input/Input.h
index e778076..7c662a7 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -170,7 +170,7 @@
enum { MAX_AXES = 14 }; // 14 so that sizeof(PointerCoords) == 64
// Bitfield of axes that are present in this structure.
- uint64_t bits;
+ uint64_t bits __attribute__((aligned(8)));
// Values of axes that are stored in this structure packed in order by axis id
// for each axis that is present in the structure according to 'bits'.
diff --git a/include/input/InputTransport.h b/include/input/InputTransport.h
index 8ffdfca..e7e383b 100644
--- a/include/input/InputTransport.h
+++ b/include/input/InputTransport.h
@@ -39,6 +39,9 @@
/*
* Intermediate representation used to send input events and related signals.
+ *
+ * Note that this structure is used for IPCs so its layout must be identical
+ * on 64 and 32 bit processes. This is tested in StructLayout_test.cpp.
*/
struct InputMessage {
enum {
@@ -49,13 +52,17 @@
struct Header {
uint32_t type;
- uint32_t padding; // 8 byte alignment for the body that follows
+ // We don't need this field in order to align the body below but we
+ // leave it here because InputMessage::size() and other functions
+ // compute the size of this structure as sizeof(Header) + sizeof(Body).
+ uint32_t padding;
} header;
+ // Body *must* be 8 byte aligned.
union Body {
struct Key {
uint32_t seq;
- nsecs_t eventTime;
+ nsecs_t eventTime __attribute__((aligned(8)));
int32_t deviceId;
int32_t source;
int32_t action;
@@ -64,7 +71,7 @@
int32_t scanCode;
int32_t metaState;
int32_t repeatCount;
- nsecs_t downTime;
+ nsecs_t downTime __attribute__((aligned(8)));
inline size_t size() const {
return sizeof(Key);
@@ -73,7 +80,7 @@
struct Motion {
uint32_t seq;
- nsecs_t eventTime;
+ nsecs_t eventTime __attribute__((aligned(8)));
int32_t deviceId;
int32_t source;
int32_t action;
@@ -81,13 +88,14 @@
int32_t metaState;
int32_t buttonState;
int32_t edgeFlags;
- nsecs_t downTime;
+ nsecs_t downTime __attribute__((aligned(8)));
float xOffset;
float yOffset;
float xPrecision;
float yPrecision;
uint32_t pointerCount;
- struct Pointer {
+ // Note that PointerCoords requires 8 byte alignment.
+ struct Pointer{
PointerProperties properties;
PointerCoords coords;
} pointers[MAX_POINTERS];
@@ -112,7 +120,7 @@
return sizeof(Finished);
}
} finished;
- } body;
+ } __attribute__((aligned(8))) body;
bool isValid(size_t actualSize) const;
size_t size() const;
diff --git a/libs/input/tests/Android.mk b/libs/input/tests/Android.mk
index c62dff1..9612a65 100644
--- a/libs/input/tests/Android.mk
+++ b/libs/input/tests/Android.mk
@@ -29,5 +29,16 @@
$(eval include $(BUILD_NATIVE_TEST)) \
)
+# NOTE: This is a compile time test, and does not need to be
+# run. All assertions are static_asserts and will fail during
+# buildtime if something's wrong.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := StructLayout_test.cpp
+LOCAL_MODULE := StructLayout_test
+LOCAL_CFLAGS := -std=c++11 -O0
+LOCAL_MULTILIB := both
+include $(BUILD_STATIC_LIBRARY)
+
+
# Build the manual test programs.
include $(call all-makefiles-under, $(LOCAL_PATH))
diff --git a/libs/input/tests/StructLayout_test.cpp b/libs/input/tests/StructLayout_test.cpp
new file mode 100644
index 0000000..83bc6ae
--- /dev/null
+++ b/libs/input/tests/StructLayout_test.cpp
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <input/InputTransport.h>
+#include <input/Input.h>
+
+namespace android {
+
+#define CHECK_OFFSET(type, member, expected_offset) \
+ static_assert((offsetof(type, member) == expected_offset), "")
+
+struct Foo {
+ uint32_t dummy;
+ PointerCoords coords;
+};
+
+void TestPointerCoordsAlignment() {
+ CHECK_OFFSET(Foo, coords, 8);
+}
+
+void TestInputMessageAlignment() {
+ CHECK_OFFSET(InputMessage, body, 8);
+
+ CHECK_OFFSET(InputMessage::Body::Key, seq, 0);
+ CHECK_OFFSET(InputMessage::Body::Key, eventTime, 8);
+ CHECK_OFFSET(InputMessage::Body::Key, deviceId, 16);
+ CHECK_OFFSET(InputMessage::Body::Key, source, 20);
+ CHECK_OFFSET(InputMessage::Body::Key, action, 24);
+ CHECK_OFFSET(InputMessage::Body::Key, flags, 28);
+ CHECK_OFFSET(InputMessage::Body::Key, keyCode, 32);
+ CHECK_OFFSET(InputMessage::Body::Key, scanCode, 36);
+ CHECK_OFFSET(InputMessage::Body::Key, metaState, 40);
+ CHECK_OFFSET(InputMessage::Body::Key, repeatCount, 44);
+ CHECK_OFFSET(InputMessage::Body::Key, downTime, 48);
+
+ CHECK_OFFSET(InputMessage::Body::Motion, seq, 0);
+ CHECK_OFFSET(InputMessage::Body::Motion, eventTime, 8);
+ CHECK_OFFSET(InputMessage::Body::Motion, deviceId, 16);
+ CHECK_OFFSET(InputMessage::Body::Motion, source, 20);
+ CHECK_OFFSET(InputMessage::Body::Motion, action, 24);
+ CHECK_OFFSET(InputMessage::Body::Motion, flags, 28);
+ CHECK_OFFSET(InputMessage::Body::Motion, metaState, 32);
+ CHECK_OFFSET(InputMessage::Body::Motion, buttonState, 36);
+ CHECK_OFFSET(InputMessage::Body::Motion, edgeFlags, 40);
+ CHECK_OFFSET(InputMessage::Body::Motion, downTime, 48);
+ CHECK_OFFSET(InputMessage::Body::Motion, xOffset, 56);
+ CHECK_OFFSET(InputMessage::Body::Motion, yOffset, 60);
+ CHECK_OFFSET(InputMessage::Body::Motion, xPrecision, 64);
+ CHECK_OFFSET(InputMessage::Body::Motion, yPrecision, 68);
+ CHECK_OFFSET(InputMessage::Body::Motion, pointerCount, 72);
+ CHECK_OFFSET(InputMessage::Body::Motion, pointers, 80);
+}
+
+} // namespace android