tree de662b6e4d8303abae9062e45edb7a481cb6bfb9
parent ee477524b461324ed8fc950f451c3671dc79f12e
author Ravikiran G Thirumalai <kiran@scalex86.org> 1225400361 -0700
committer Ingo Molnar <mingo@elte.hu> 1225407281 +0100

x86: fix /dev/mem mmap breakage when PAT is disabled

Impact: allow /dev/mem mmaps on non-PAT CPUs/platforms

Fix mmap to /dev/mem when CONFIG_X86_PAT is off and CONFIG_STRICT_DEVMEM is
off

mmap to /dev/mem on kernel memory has been failing since the
introduction of PAT (CONFIG_STRICT_DEVMEM=n case).   Seems like
the check to avoid cache aliasing with PAT is kicking in even
when PAT is disabled. The bug seems to have crept in 2.6.26.

This patch makes sure that the mmap to regular
kernel memory succeeds if CONFIG_STRICT_DEVMEM=n and
PAT is disabled, and the checks to avoid cache aliasing
still happens if PAT is enabled.

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Tested-by: Tim Sirianni <tim@scalemp.com>
Cc: <stable@kernel.org>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>