compat: Get rid of (get|put)_compat_time(val|spec)

We have two APIs for compatiblity timespec/val, with confusingly
similar names.  compat_(get|put)_time(val|spec) *do* handle the case
where COMPAT_USE_64BIT_TIME is set, whereas
(get|put)_compat_time(val|spec) do not.  This is an accident waiting
to happen.

Clean it up by favoring the full-service version; the limited version
is replaced with double-underscore versions static to kernel/compat.c.

A common pattern is to convert a struct timespec to kernel format in
an allocation on the user stack.  Unfortunately it is open-coded in
several places.  Since this allocation isn't actually needed if
COMPAT_USE_64BIT_TIME is true (since user format == kernel format)
encapsulate that whole pattern into the function
compat_convert_timespec().  An equivalent function should be written
for struct timeval if it is needed in the future.

Finally, get rid of compat_(get|put)_timeval_convert(): each was only
used once, and the latter was not even doing what the function said
(no conversion actually was being done.)  Moving the conversion into
compat_sys_settimeofday() itself makes the code much more similar to
sys_settimeofday() itself.

v3: Remove unused compat_convert_timeval().

v2: Drop bogus "const" in the destination argument for
    compat_convert_time*().

Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Tested-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 3 insertions, 16 deletions

diff --git a/ipc/compat_mq.c b/ipc/compat_mq.c
index 63d7c6de335b..a9cf16378d7a 100644
--- a/ipc/compat_mq.c
+++ b/ipc/compat_mq.c
@@ -64,20 +64,6 @@ asmlinkage long compat_sys_mq_open(const char __user *u_name,
         return sys_mq_open(u_name, oflag, mode, p);
 }
 
-static int compat_prepare_timeout(struct timespec __user **p,
-                                  const struct compat_timespec __user *u)
-{
-        struct timespec ts;
-        if (!u) {
-                *p = NULL;
-                return 0;
-        }
-        *p = compat_alloc_user_space(sizeof(ts));
-        if (get_compat_timespec(&ts, u) || copy_to_user(*p, &ts, sizeof(ts)))
-                return -EFAULT;
-        return 0;
-}
-
 asmlinkage long compat_sys_mq_timedsend(mqd_t mqdes,
                         const char __user *u_msg_ptr,
                         size_t msg_len, unsigned int msg_prio,
@@ -85,7 +71,7 @@ asmlinkage long compat_sys_mq_timedsend(mqd_t mqdes,
 {
         struct timespec __user *u_ts;
 
-        if (compat_prepare_timeout(&u_ts, u_abs_timeout))
+        if (compat_convert_timespec(&u_ts, u_abs_timeout))
                 return -EFAULT;
 
         return sys_mq_timedsend(mqdes, u_msg_ptr, msg_len,
@@ -98,7 +84,8 @@ asmlinkage ssize_t compat_sys_mq_timedreceive(mqd_t mqdes,
                         const struct compat_timespec __user *u_abs_timeout)
 {
         struct timespec __user *u_ts;
-        if (compat_prepare_timeout(&u_ts, u_abs_timeout))
+
+        if (compat_convert_timespec(&u_ts, u_abs_timeout))
                 return -EFAULT;
 
         return sys_mq_timedreceive(mqdes, u_msg_ptr, msg_len,