[RFC,14/20] timens: Add align for timens_offsets

Submitted by Dmitry Safonov on Sept. 19, 2018, 8:50 p.m.

Details

Message ID 20180919205037.9574-15-dima@arista.com
State New
Series "Series without cover letter"
Headers show

Commit Message

Dmitry Safonov Sept. 19, 2018, 8:50 p.m.
Align offsets so that Time Namespace will work for ia32 applications on
x86_64 host.

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 include/linux/timens_offsets.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

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diff --git a/include/linux/timens_offsets.h b/include/linux/timens_offsets.h
index 777530c46852..92a8ea5601eb 100644
--- a/include/linux/timens_offsets.h
+++ b/include/linux/timens_offsets.h
@@ -2,9 +2,16 @@ 
 #ifndef _LINUX_TIME_OFFSETS_H
 #define _LINUX_TIME_OFFSETS_H
 
+/*
+ * Time offsets need align as they're placed on vvar page,
+ * which should have tail paddings on ia32 vdso.
+ * Otherwise as u64 has align(4), vvar offsets will differ.
+ * On 64-bit big-endian systems vdso should convert to timespec64
+ * to timespec because of a padding occuring between the fields.
+ */
 struct timens_offsets {
-	struct timespec64  monotonic_time_offset;
-	struct timespec64  monotonic_boottime_offset;
+	struct timespec64  monotonic_time_offset __aligned(8);
+	struct timespec64  monotonic_boottime_offset __aligned(8);
 };
 
 #endif