y2038: x86: Extend sysvipc data structures

This extends the x86 copy of the sysvipc data structures to deal with
32-bit user space that has 64-bit time_t and wants to see timestamps
beyond 2038.

Fortunately, x86 has padding for this purpose in all the data structures,
so we can just add extra fields. With msgid64_ds and shmid64_ds, the
data structure is identical to the asm-generic version, which we have
already extended.

For some reason however, the 64-bit version of semid64_ds ended up with
extra padding, so I'm implementing the same approach as the asm-generic
version here, by using separate fields for the upper and lower halves
of the two timestamps.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/x86/include/asm/compat.h

@@ -134,10 +134,10 @@ struct compat_ipc64_perm {
 
 struct compat_semid64_ds {
 	struct compat_ipc64_perm sem_perm;
-	compat_time_t  sem_otime;
-	compat_ulong_t __unused1;
-	compat_time_t  sem_ctime;
-	compat_ulong_t __unused2;
+	compat_ulong_t sem_otime;
+	compat_ulong_t sem_otime_high;
+	compat_ulong_t sem_ctime;
+	compat_ulong_t sem_ctime_high;
 	compat_ulong_t sem_nsems;
 	compat_ulong_t __unused3;
 	compat_ulong_t __unused4;
@@ -145,12 +145,12 @@ struct compat_semid64_ds {
 
 struct compat_msqid64_ds {
 	struct compat_ipc64_perm msg_perm;
-	compat_time_t  msg_stime;
-	compat_ulong_t __unused1;
-	compat_time_t  msg_rtime;
-	compat_ulong_t __unused2;
-	compat_time_t  msg_ctime;
-	compat_ulong_t __unused3;
+	compat_ulong_t msg_stime;
+	compat_ulong_t msg_stime_high;
+	compat_ulong_t msg_rtime;
+	compat_ulong_t msg_rtime_high;
+	compat_ulong_t msg_ctime;
+	compat_ulong_t msg_ctime_high;
 	compat_ulong_t msg_cbytes;
 	compat_ulong_t msg_qnum;
 	compat_ulong_t msg_qbytes;
@@ -163,12 +163,12 @@ struct compat_msqid64_ds {
 struct compat_shmid64_ds {
 	struct compat_ipc64_perm shm_perm;
 	compat_size_t  shm_segsz;
-	compat_time_t  shm_atime;
-	compat_ulong_t __unused1;
-	compat_time_t  shm_dtime;
-	compat_ulong_t __unused2;
-	compat_time_t  shm_ctime;
-	compat_ulong_t __unused3;
+	compat_ulong_t shm_atime;
+	compat_ulong_t shm_atime_high;
+	compat_ulong_t shm_dtime;
+	compat_ulong_t shm_dtime_high;
+	compat_ulong_t shm_ctime;
+	compat_ulong_t shm_ctime_high;
 	compat_pid_t   shm_cpid;
 	compat_pid_t   shm_lpid;
 	compat_ulong_t shm_nattch;

arch/x86/include/uapi/asm/sembuf.h

@@ -8,15 +8,24 @@
  * between kernel and user space.
  *
  * Pad space is left for:
- * - 64-bit time_t to solve y2038 problem
  * - 2 miscellaneous 32-bit values
+ *
+ * x86_64 and x32 incorrectly added padding here, so the structures
+ * are still incompatible with the padding on x86.
  */
 struct semid64_ds {
 	struct ipc64_perm sem_perm;	/* permissions .. see ipc.h */
+#ifdef __i386__
+	unsigned long	sem_otime;	/* last semop time */
+	unsigned long	sem_otime_high;
+	unsigned long	sem_ctime;	/* last change time */
+	unsigned long	sem_ctime_high;
+#else
 	__kernel_time_t	sem_otime;	/* last semop time */
 	__kernel_ulong_t __unused1;
 	__kernel_time_t	sem_ctime;	/* last change time */
 	__kernel_ulong_t __unused2;
+#endif
 	__kernel_ulong_t sem_nsems;	/* no. of semaphores in array */
 	__kernel_ulong_t __unused3;
 	__kernel_ulong_t __unused4;