tree d4831170cd6c5373f0daab7589e70a4821c9099d
parent 01227a889ed56ae53aeebb9f93be9d54dd8b2de8
author Anton Blanchard <anton@samba.org> 1367438793 +0000
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> 1367796335 +1000

powerpc: Emulate non privileged DSCR read and write

POWER8 allows read and write of the DSCR in userspace. We added
kernel emulation so applications could always use the instructions
regardless of the CPU type.

Unfortunately there are two SPRs for the DSCR and we only added
emulation for the privileged one. Add code to match the non
privileged one.

A simple test was created to verify the fix:

http://ozlabs.org/~anton/junkcode/user_dscr_test.c

Without the patch we get a SIGILL and it passes with the patch.

Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>