[PATCH v2 06/13] y2038: mips: extend sysvipc data structures

From: Arnd Bergmann
Date: Thu Apr 12 2018 - 10:22:46 EST

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@xxxxxxxx>
---
arch/mips/include/asm/compat.h | 38 +++++++++++++------------
arch/mips/include/uapi/asm/msgbuf.h | 57 ++++++++++++++++++++++++-------------
arch/mips/include/uapi/asm/sembuf.h | 15 ++++++++--
arch/mips/include/uapi/asm/shmbuf.h | 23 +++++++++++++--
4 files changed, 92 insertions(+), 41 deletions(-)

diff --git a/arch/mips/include/asm/compat.h b/arch/mips/include/asm/compat.h
index 3e548ee99a2f..2e058c4d63a3 100644
--- a/arch/mips/include/asm/compat.h
+++ b/arch/mips/include/asm/compat.h
@@ -157,35 +157,35 @@ 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;
@@ -199,14 +199,16 @@ 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 eb4d0f9d7364..46aa15b13e4e 100644
--- a/arch/mips/include/uapi/asm/msgbuf.h
+++ b/arch/mips/include/uapi/asm/msgbuf.h
@@ -9,33 +9,15 @@
* between kernel and user space.
*
* Pad space is left for:
- * - extension of time_t to 64-bit on 32-bitsystem to solve the y2038 problem
* - 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 */
@@ -44,5 +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 2c0f507ab7d1..cbd19e0f0630 100644
--- a/arch/mips/include/uapi/asm/sembuf.h
+++ b/arch/mips/include/uapi/asm/sembuf.h
@@ -7,10 +7,11 @@
* 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 */
@@ -19,5 +20,15 @@ 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 379e6bca518b..9b9bba3401f2 100644
--- a/arch/mips/include/uapi/asm/shmbuf.h
+++ b/arch/mips/include/uapi/asm/shmbuf.h
@@ -7,10 +7,13 @@
* 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) */
@@ -23,6 +26,22 @@ 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;
--
2.9.0