y2038: xtensa: Extend sysvipc data structures

xtensa, uses a nonstandard variation of the generic sysvipc
data structures, intended to have the padding moved around
so it can deal with big-endian 32-bit user space that has
64-bit time_t.

xtensa tries hard to define the structures so they work
in both big-endian and little-endian systems with padding
on the right side.
However, they only succeeded for for two of the three structures,
and their struct shmid64_ds ended up being defined in two
identical copies, and the big-endian one is wrong.

This takes just take the same approach here that we have for
the asm-generic headers and adds separate 32-bit fields for the
upper halves of the timestamps, to let libc deal with the mess
in user space.

Signed-off-by: Arnd Bergmann <[e-mail]>

arch/xtensa/include/uapi/asm/msgbuf.h

···
  * between kernel and user space.
  *
  * Pad space is left for:
- * - 64-bit time_t to solve y2038 problem
  * - 2 miscellaneous 32-bit values
  *
  * This file is subject to the terms and conditions of the GNU General
···
 struct msqid64_ds {
 	struct ipc64_perm msg_perm;
 #ifdef __XTENSA_EB__
-	unsigned int	__unused1;
-	__kernel_time_t msg_stime;	/* last msgsnd time */
-	unsigned int	__unused2;
-	__kernel_time_t msg_rtime;	/* last msgrcv time */
-	unsigned int	__unused3;
-	__kernel_time_t msg_ctime;	/* last change time */
+	unsigned long  msg_stime_high;
+	unsigned long  msg_stime;	/* last msgsnd time */
+	unsigned long  msg_rtime_high;
+	unsigned long  msg_rtime;	/* last msgrcv time */
+	unsigned long  msg_ctime_high;
+	unsigned long  msg_ctime;	/* last change time */
 #elif defined(__XTENSA_EL__)
-	__kernel_time_t msg_stime;	/* last msgsnd time */
-	unsigned int	__unused1;
-	__kernel_time_t msg_rtime;	/* last msgrcv time */
-	unsigned int	__unused2;
-	__kernel_time_t msg_ctime;	/* last change time */
-	unsigned int	__unused3;
+	unsigned long  msg_stime;	/* last msgsnd time */
+	unsigned long  msg_stime_high;
+	unsigned long  msg_rtime;	/* last msgrcv time */
+	unsigned long  msg_rtime_high;
+	unsigned long  msg_ctime;	/* last change time */
+	unsigned long  msg_ctime_high;
 #else
 # error processor byte order undefined!
 #endif

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

···
  * between kernel and user space.
  *
  * Pad space is left for:
- * - 64-bit time_t to solve y2038 problem
  * - 2 miscellaneous 32-bit values
  *
  */
···
 struct semid64_ds {
 	struct ipc64_perm sem_perm;		/* permissions .. see ipc.h */
 #ifdef __XTENSA_EL__
-	__kernel_time_t	sem_otime;		/* last semop time */
-	unsigned long	__unused1;
-	__kernel_time_t	sem_ctime;		/* last change time */
-	unsigned long	__unused2;
+	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
-	unsigned long	__unused1;
-	__kernel_time_t	sem_otime;		/* last semop time */
-	unsigned long	__unused2;
-	__kernel_time_t	sem_ctime;		/* last change time */
+	unsigned long	sem_otime_high;
+	unsigned long	sem_otime;		/* last semop time */
+	unsigned long	sem_ctime_high;
+	unsigned long	sem_ctime;		/* last change time */
 #endif
 	unsigned long	sem_nsems;		/* no. of semaphores in array */
 	unsigned long	__unused3;

arch/xtensa/include/uapi/asm/shmbuf.h

···
  *
  * The shmid64_ds structure for Xtensa architecture.
  * Note extra padding because this structure is passed back and forth
- * between kernel and user space.
+ * between kernel and user space, but the padding is on the wrong
+ * side for big-endian xtensa, for historic reasons.
  *
  * Pad space is left for:
- * - 64-bit time_t to solve y2038 problem
  * - 2 miscellaneous 32-bit values
  *
  * This file is subject to the terms and conditions of the GNU General Public
···
 #ifndef _XTENSA_SHMBUF_H
 #define _XTENSA_SHMBUF_H
 
-#if defined (__XTENSA_EL__)
 struct shmid64_ds {
 	struct ipc64_perm	shm_perm;	/* operation perms */
 	size_t			shm_segsz;	/* size of segment (bytes) */
-	__kernel_time_t		shm_atime;	/* last attach time */
-	unsigned long		__unused1;
-	__kernel_time_t		shm_dtime;	/* last detach time */
-	unsigned long		__unused2;
-	__kernel_time_t		shm_ctime;	/* last change time */
-	unsigned long		__unused3;
+	unsigned long		shm_atime;	/* last attach time */
+	unsigned long		shm_atime_high;
+	unsigned long		shm_dtime;	/* last detach time */
+	unsigned long		shm_dtime_high;
+	unsigned long		shm_ctime;	/* last change time */
+	unsigned long		shm_ctime_high;
 	__kernel_pid_t		shm_cpid;	/* pid of creator */
 	__kernel_pid_t		shm_lpid;	/* pid of last operator */
 	unsigned long		shm_nattch;	/* no. of current attaches */
 	unsigned long		__unused4;
 	unsigned long		__unused5;
 };
-#elif defined (__XTENSA_EB__)
-struct shmid64_ds {
-	struct ipc64_perm	shm_perm;	/* operation perms */
-	size_t			shm_segsz;	/* size of segment (bytes) */
-	__kernel_time_t		shm_atime;	/* last attach time */
-	unsigned long		__unused1;
-	__kernel_time_t		shm_dtime;	/* last detach time */
-	unsigned long		__unused2;
-	__kernel_time_t		shm_ctime;	/* last change time */
-	unsigned long		__unused3;
-	__kernel_pid_t		shm_cpid;	/* pid of creator */
-	__kernel_pid_t		shm_lpid;	/* pid of last operator */
-	unsigned long		shm_nattch;	/* no. of current attaches */
-	unsigned long		__unused4;
-	unsigned long		__unused5;
-};
-#else
-# error endian order not defined
-#endif
-
 
 struct shminfo64 {
 	unsigned long	shmmax;