linux/arch/parisc/mm
Helge Deller d19f5e41b3 parisc: Clean up fixup routines for get_user()/put_user()
Al Viro noticed that userspace accesses via get_user()/put_user() can be
simplified a lot with regard to usage of the exception handling.

This patch implements a fixup routine for get_user() and put_user() in such
that the exception handler will automatically load -EFAULT into the register
%r8 (the error value) in case on a fault on userspace.  Additionally the fixup
routine will zero the target register on fault in case of a get_user() call.
The target register is extracted out of the faulting assembly instruction.

This patch brings a few benefits over the old implementation:
1. Exception handling gets much cleaner, easier and smaller in size.
2. Helper functions like fixup_get_user_skip_1 (all of fixup.S) can be dropped.
3. No need to hardcode %r9 as target register for get_user() any longer. This
   helps the compiler register allocator and thus creates less assembler
   statements.
4. No dependency on the exception_data contents any longer.
5. Nested faults will be handled cleanly.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Cc: <stable@vger.kernel.org> # v4.9+
Signed-off-by: Helge Deller <deller@gmx.de>
2017-03-29 21:50:36 +02:00
..
fault.c parisc: Clean up fixup routines for get_user()/put_user() 2017-03-29 21:50:36 +02:00
hugetlbpage.c sched/headers: Prepare for new header dependencies before moving more code to <linux/sched/mm.h> 2017-03-02 08:42:30 +01:00
init.c arch, mm: remove arch specific show_mem 2017-02-22 16:41:30 -08:00
ioremap.c parisc: fix wrong page aligned size calculation in ioremapping code 2010-08-12 08:43:29 -07:00
Makefile parisc: Add Huge Page and HUGETLBFS support 2015-11-22 12:23:10 +01:00