futex: move user address verification up to common code

When debugging the read-only hugepage case, I was confused by the fact
that get_futex_key() did an access_ok() only for the non-shared futex
case, since the user address checking really isn't in any way specific
to the private key handling.

Now, it turns out that the shared key handling does effectively do the
equivalent checks inside get_user_pages_fast() (it doesn't actually
check the address range on x86, but does check the page protections for
being a user page).  So it wasn't actually a bug, but the fact that we
treat the address differently for private and shared futexes threw me
for a loop.

Just move the check up, so that it gets done for both cases.  Also, use
the 'rw' parameter for the type, even if it doesn't actually matter any
more (it's a historical artifact of the old racy i386 "page faults from
kernel space don't check write protections").

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
msm: kgsl: hold a process_private refcount in process_mem_print

There is a possible race condition where the process can be going
away while its debugfs 'mem' file is being read, which could cause
memory corruption.

Conflicts:

	drivers/gpu/msm/kgsl.c

CRs-Fixed: 627780
Change-Id: I697486faeb3f186fd1220d0acc1e449a4f7b77b0
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>
msm: kgsl: Look up the process struct in process_mem_open()

The pointer to an active process struct stands the risk of going stale
if process_mem_open() is called just before the debugfs dentry is
destroyed.  Instead of storing and using the pointer pass the process pid
to process_mem_open() and do a lookup to ensure that we always get active
processes.

Change-Id: Ic0dedbad3a3b54dc96251663fdf89c466fef3ca5
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Makefile: tweaks