tree 7ade7d69461250a39fabcd8a79d885253c6fd299
parent 7e27d6e778cd87b6f2415515d7127eba53fe5d02
author Russell King <rmk+kernel@arm.linux.org.uk> 1277150598 +0100
committer Russell King <rmk+kernel@arm.linux.org.uk> 1277150598 +0100

ARM: Prohibit ioremap() on kernel managed RAM

ARMv6 and above have a restriction whereby aliasing virtual:physical
mappings must not have differing memory type and sharability
attributes.  Strictly, this covers the memory type (strongly ordered,
device, memory), cache attributes (uncached, write combine, write
through, write back read alloc, write back write alloc) and the
shared bit.

However, using ioremap() and its variants on system RAM results in
mappings which differ in these attributes from the main system RAM
mapping.  Other architectures which similar restrictions approch this
problem in the same way - they do not permit ioremap on main system
RAM.

Make ARM behave in the same way, with a WARN_ON() such that users can
be traced and an alternative approach found.

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