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[PATCH 3/9] y2038: mips: extend sysvipc data structures

From: Arnd Bergmann <arnd at arndb dot de>
To: y2038 at lists dot linaro dot org
Cc: baolin dot wang at linaro dot org, albert dot aribaud at 3adev dot fr, john dot stultz at linaro dot org, bamvor dot zhangjian at linaro dot org, ruchandani dot tina at gmail dot com, linux-api at vger dot kernel dot org, linux-kernel at vger dot kernel dot org, libc-alpha at sourceware dot org, linux-arch at vger dot kernel dot org, Manfred Spraul <manfred at colorfullife dot com>, Michael Kerrisk <mtk dot manpages at gmail dot com>, Arnd Bergmann <arnd at arndb dot de>
Date: Wed, 20 May 2015 17:07:19 +0200
Subject: [PATCH 3/9] y2038: mips: extend sysvipc data structures
Authentication-results: sourceware.org; auth=none
References: <1432134445-804487-1-git-send-email-arnd at arndb dot de>

MIPS is the weirdest case for sysvipc, because each of the
three data structures is done differently:

* msqid64_ds has padding in the right place so we could in theory
  extend this one to just have 64-bit values instead of time_t.
  As this does not work for most of the other combinations,
  we just handle it in the common manner though.

* semid64_ds has no padding for 64-bit time_t, but has two reserved
  'long' fields, which are sufficient to extend the sem_otime
  and sem_ctime fields to 64 bit. In order to do this, the libc
  implementation will have to copy the data into another structure
  that has the fields in a different order. MIPS is the only
  architecture with this problem, so this is best done in MIPS
  specific libc code.

* shmid64_ds is slightly worse than that, because it has three
  time_t fields but only two unused 32-bit words. As a workaround,
  we extend each field only by 16 bits, ending up with 48-bit
  timestamps that user space again has to work around by itself.

The compat versions of the data structures are changed in the
same way.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/mips/include/asm/compat.h      | 38 +++++++++++++------------
 arch/mips/include/uapi/asm/msgbuf.h | 56 +++++++++++++++++++++++++------------
 arch/mips/include/uapi/asm/sembuf.h | 15 ++++++++--
 arch/mips/include/uapi/asm/shmbuf.h | 23 +++++++++++++--
 4 files changed, 92 insertions(+), 40 deletions(-)

diff --git a/arch/mips/include/asm/compat.h b/arch/mips/include/asm/compat.h
index 6495b37a6fbc..97e014aa2bf3 100644
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -225,35 +225,35 @@ struct compat_ipc64_perm {
 
 struct compat_semid64_ds {
 	struct compat_ipc64_perm sem_perm;
-	compat_time_t	sem_otime;
-	compat_time_t	sem_ctime;
+	compat_ulong_t	sem_otime;
+	compat_ulong_t	sem_ctime;
 	compat_ulong_t	sem_nsems;
-	compat_ulong_t	__unused1;
-	compat_ulong_t	__unused2;
+	compat_ulong_t	sem_otime_high;
+	compat_ulong_t	sem_ctime_high;
 };
 
 struct compat_msqid64_ds {
 	struct compat_ipc64_perm msg_perm;
 #ifndef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused1;
+	compat_ulong_t	msg_stime_high;
 #endif
-	compat_time_t	msg_stime;
+	compat_ulong_t	msg_stime;
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused1;
+	compat_ulong_t	msg_stime_high;
 #endif
 #ifndef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused2;
+	compat_ulong_t	msg_rtime_high;
 #endif
-	compat_time_t	msg_rtime;
+	compat_ulong_t	msg_rtime;
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused2;
+	compat_ulong_t	msg_rtime_high;
 #endif
 #ifndef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused3;
+	compat_ulong_t	msg_ctime_high;
 #endif
-	compat_time_t	msg_ctime;
+	compat_ulong_t	msg_ctime;
 #ifdef CONFIG_CPU_LITTLE_ENDIAN
-	compat_ulong_t	__unused3;
+	compat_ulong_t	msg_ctime_high;
 #endif
 	compat_ulong_t	msg_cbytes;
 	compat_ulong_t	msg_qnum;
@@ -267,14 +267,16 @@ 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_time_t	shm_dtime;
-	compat_time_t	shm_ctime;
+	compat_ulong_t	shm_atime;
+	compat_ulong_t	shm_dtime;
+	compat_ulong_t	shm_ctime;
 	compat_pid_t	shm_cpid;
 	compat_pid_t	shm_lpid;
 	compat_ulong_t	shm_nattch;
-	compat_ulong_t	__unused1;
-	compat_ulong_t	__unused2;
+	compat_ushort_t	shm_atime_high;
+	compat_ushort_t	shm_dtime_high;
+	compat_ushort_t	shm_ctime_high;
+	compat_ushort_t	__unused2;
 };
 
 /* MIPS has unusual order of fields in stack_t */
diff --git a/arch/mips/include/uapi/asm/msgbuf.h b/arch/mips/include/uapi/asm/msgbuf.h
index df849e87d9ae..460c3117912c 100644
--- a/arch/mips/include/uapi/asm/msgbuf.h
+++ b/arch/mips/include/uapi/asm/msgbuf.h
@@ -12,29 +12,12 @@
  * - 2 miscellaneous unsigned long values
  */
 
+#if defined(__mips64)
 struct msqid64_ds {
 	struct ipc64_perm msg_perm;
-#if !defined(__mips64) && defined(__MIPSEB__)
-	unsigned long	__unused1;
-#endif
 	__kernel_time_t msg_stime;	/* last msgsnd time */
-#if !defined(__mips64) && defined(__MIPSEL__)
-	unsigned long	__unused1;
-#endif
-#if !defined(__mips64) && defined(__MIPSEB__)
-	unsigned long	__unused2;
-#endif
 	__kernel_time_t msg_rtime;	/* last msgrcv time */
-#if !defined(__mips64) && defined(__MIPSEL__)
-	unsigned long	__unused2;
-#endif
-#if !defined(__mips64) && defined(__MIPSEB__)
-	unsigned long	__unused3;
-#endif
 	__kernel_time_t msg_ctime;	/* last change time */
-#if !defined(__mips64) && defined(__MIPSEL__)
-	unsigned long	__unused3;
-#endif
 	unsigned long  msg_cbytes;	/* current number of bytes on queue */
 	unsigned long  msg_qnum;	/* number of messages in queue */
 	unsigned long  msg_qbytes;	/* max number of bytes on queue */
@@ -43,5 +26,42 @@ struct msqid64_ds {
 	unsigned long  __unused4;
 	unsigned long  __unused5;
 };
+#elif defined (__MIPSEB__)
+struct msqid64_ds {
+	struct ipc64_perm msg_perm;
+	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 */
+	unsigned long  msg_cbytes;	/* current number of bytes on queue */
+	unsigned long  msg_qnum;	/* number of messages in queue */
+	unsigned long  msg_qbytes;	/* max number of bytes on queue */
+	__kernel_pid_t msg_lspid;	/* pid of last msgsnd */
+	__kernel_pid_t msg_lrpid;	/* last receive pid */
+	unsigned long  __unused4;
+	unsigned long  __unused5;
+};
+#elif defined (__MIPSEL__)
+struct msqid64_ds {
+	struct ipc64_perm msg_perm;
+	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;
+	unsigned long  msg_cbytes;	/* current number of bytes on queue */
+	unsigned long  msg_qnum;	/* number of messages in queue */
+	unsigned long  msg_qbytes;	/* max number of bytes on queue */
+	__kernel_pid_t msg_lspid;	/* pid of last msgsnd */
+	__kernel_pid_t msg_lrpid;	/* last receive pid */
+	unsigned long  __unused4;
+	unsigned long  __unused5;
+};
+#else
+#warning no endianess set
+#endif
 
 #endif /* _ASM_MSGBUF_H */
diff --git a/arch/mips/include/uapi/asm/sembuf.h b/arch/mips/include/uapi/asm/sembuf.h
index e1085ac880f2..055fddb4fdb0 100644
--- a/arch/mips/include/uapi/asm/sembuf.h
+++ b/arch/mips/include/uapi/asm/sembuf.h
@@ -6,10 +6,11 @@
  * Note extra padding because this structure is passed back and forth
  * between kernel and user space.
  *
- * Pad space is left for:
- * - 2 miscellaneous 64-bit values
+ * Pad space is left for 2 miscellaneous 64-bit values on mips64,
+ * but used for the upper 32 bit of the time values on mips32.
  */
 
+#ifdef __mips64
 struct semid64_ds {
 	struct ipc64_perm sem_perm;		/* permissions .. see ipc.h */
 	__kernel_time_t sem_otime;		/* last semop time */
@@ -18,5 +19,15 @@ struct semid64_ds {
 	unsigned long	__unused1;
 	unsigned long	__unused2;
 };
+#else
+struct semid64_ds {
+	struct ipc64_perm sem_perm;		/* permissions .. see ipc.h */
+	unsigned long   sem_otime;		/* last semop time */
+	unsigned long   sem_ctime;		/* last change time */
+	unsigned long	sem_nsems;		/* no. of semaphores in array */
+	unsigned long	sem_otime_high;
+	unsigned long	sem_otime_high;
+};
+#endif
 
 #endif /* _ASM_SEMBUF_H */
diff --git a/arch/mips/include/uapi/asm/shmbuf.h b/arch/mips/include/uapi/asm/shmbuf.h
index f994438277bf..3a1399f7dfdc 100644
--- a/arch/mips/include/uapi/asm/shmbuf.h
+++ b/arch/mips/include/uapi/asm/shmbuf.h
@@ -6,10 +6,13 @@
  * Note extra padding because this structure is passed back and forth
  * between kernel and user space.
  *
- * Pad space is left for:
- * - 2 miscellaneous 32-bit rsp. 64-bit values
+ * As MIPS was lacking proper padding after shm_?time, we use 48 bits
+ * of the padding at the end to store a few additional bits of the time.
+ * libc implementations need to take care to convert this into a proper
+ * data structure when moving to 64-bit time_t.
  */
 
+#ifdef __mips64
 struct shmid64_ds {
 	struct ipc64_perm	shm_perm;	/* operation perms */
 	size_t			shm_segsz;	/* size of segment (bytes) */
@@ -22,6 +25,22 @@ struct shmid64_ds {
 	unsigned long		__unused1;
 	unsigned long		__unused2;
 };
+#else
+struct shmid64_ds {
+	struct ipc64_perm	shm_perm;	/* operation perms */
+	size_t			shm_segsz;	/* size of segment (bytes) */
+	unsigned long		shm_atime;	/* last attach time */
+	unsigned long		shm_dtime;	/* last detach time */
+	unsigned long		shm_ctime;	/* last change time */
+	__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 short		shm_atime_high;
+	unsigned short		shm_dtime_high;
+	unsigned short		shm_ctime_high;
+	unsigned short		__unused1;
+};
+#endif
 
 struct shminfo64 {
 	unsigned long	shmmax;
-- 
2.1.0.rc2

References:
- [PATCH 0/9] converting system calls to 64-bit time_t, part 2
  - From: Arnd Bergmann

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