This patch removes the domain switching functionality via the set_fs and
__switch_to functions on cores that have a TLS register.

Currently, the ioremap and vmalloc areas share the same level 1 page
tables and therefore have the same domain (DOMAIN_KERNEL). When the
kernel domain is modified from Client to Manager (via the __set_fs or in
the __switch_to function), the XN (eXecute Never) bit is overridden and
newer CPUs can speculatively prefetch the ioremap'ed memory.

Linux performs the kernel domain switching to allow user-specific
functions (copy_to/from_user, get/put_user etc.) to access kernel
memory. In order for these functions to work with the kernel domain set
to Client, the patch modifies the LDRT/STRT and related instructions to
the LDR/STR ones.

The user pages access rights are also modified for kernel read-only
access rather than read/write so that the copy-on-write mechanism still
works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
(CPU_32v6K is defined) since writing the TLS value to the high vectors page
isn't possible.

The user addresses passed to the kernel are checked by the access_ok()
function so that they do not point to the kernel space.
Tested-by: NAnton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

These old symbols are meaningless now that we have memory type
support implemented.  The entire memory type field needs to be
modified rather than just a few bits twiddled.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

As of the previous commit, MT_DEVICE_IXP2000 encodes to the same
PTE bit encoding as MT_DEVICE, so it's now redundant.  Convert
MT_DEVICE_IXP2000 to use MT_DEVICE instead, and remove its aliases.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

There are actually only four separate implementations of set_pte_ext.
Use assembler macros to insert code for these into the proc-*.S files.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch adds support for the ARMv7 cores.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Most MMU-based CPUs have a restriction on the setting of the data cache
enable and mmu enable bits in the control register, whereby if the data
cache is enabled, the MMU must also be enabled.  Enabling the data
cache without the MMU is an invalid combination.

However, there are CPUs where the data cache can be enabled without the
MMU.

In order to allow these CPUs to take advantage of that, provide a
method whereby each proc-*.S file defines the control regsiter value
for use with nommu (with the MMU disabled.)  Later on, when we add
support for enabling the MMU on these devices, we can adjust the
"crval" macro to also enable the data cache for nommu.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Delete obsoleted stuff from arch Makefile and rename
constants.h to asm-offsets.h
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!