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, 10 insertions, 13 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 3f448c65511b..f7d5bc0a239f 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -141,26 +141,23 @@ struct compat_sigaction {
 };
 
 /*
- * These functions operate strictly on struct compat_time*
- */
-extern int get_compat_timespec(struct timespec *,
-			       const struct compat_timespec __user *);
-extern int put_compat_timespec(const struct timespec *,
-			       struct compat_timespec __user *);
-extern int get_compat_timeval(struct timeval *,
-			      const struct compat_timeval __user *);
-extern int put_compat_timeval(const struct timeval *,
-			      struct compat_timeval __user *);
-/*
  * These functions operate on 32- or 64-bit specs depending on
- * COMPAT_USE_64BIT_TIME, hence the void user pointer arguments and the
- * naming as compat_get/put_ rather than get/put_compat_.
+ * COMPAT_USE_64BIT_TIME, hence the void user pointer arguments.
  */
 extern int compat_get_timespec(struct timespec *, const void __user *);
 extern int compat_put_timespec(const struct timespec *, void __user *);
 extern int compat_get_timeval(struct timeval *, const void __user *);
 extern int compat_put_timeval(const struct timeval *, void __user *);
 
+/*
+ * This function convert a timespec if necessary and returns a *user
+ * space* pointer.  If no conversion is necessary, it returns the
+ * initial pointer.  NULL is a legitimate argument and will always
+ * output NULL.
+ */
+extern int compat_convert_timespec(struct timespec __user **,
+				   const void __user *);
+
 struct compat_iovec {
 	compat_uptr_t	iov_base;
 	compat_size_t	iov_len;