On most powerpc CPUs, the dcache and icache are not coherent so
between writing and executing a page, the caches must be flushed.
Userspace programs assume pages given to them by the kernel are icache
clean, so we must do this flush between the kernel clearing a page and
it being mapped into userspace for execute.  We were not doing this
for hugepages, this patch corrects the situation.

We use the same lazy mechanism as we use for normal pages, delaying
the flush until userspace actually attempts to execute from the page
in question.

Tested on G5.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Blah.  The patch [0] I recently sent fixing errors with
in_hugepage_area() and prepare_hugepage_range() for powerpc itself has
an off-by-one bug.  Furthermore, the related functions
touches_hugepage_*_range() and within_hugepage_*_range() are also
buggy.  Some of the bugs, like those addressed in [0] originated with
commit 7d24f0b8a53261709938ffabe3e00f88f6498df9 where we tweaked the
semantics of where hugepages are allowed.  Other bugs have been there
essentially forever, and are due to the undefined behaviour of '<<'
with shift counts greater than the type width (LOW_ESID_MASK could
return non-zero for high ranges with the right congruences).

The good news is that I now have a testsuite which should pick up
things like this if they creep in again.

[0] "powerpc-fix-for-hugepage-areas-straddling-4gb-boundary"

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Commit 7d24f0b8a53261709938ffabe3e00f88f6498df9 fixed bugs in the ppc64 SLB
miss handler with respect to hugepage handling, and in the process tweaked
the semantics of the hugepage address masks in mm_context_t.

Unfortunately, it left out a couple of necessary changes to go with that
change.  First, the in_hugepage_area() macro was not updated to match,
second prepare_hugepage_range() was not updated to correctly handle
hugepages regions which straddled the 4GB point.

The latter appears only to cause process-hangs when attempting to map such
a region, but the former can cause oopses if a get_user_pages() is
triggered at the wrong point.  This patch addresses both bugs.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Email address update, changing old work address to personal (permanent)
one.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

The result is mostly similar to the original ppc64 version but with
some adaptations for 32-bit compilation.

include/asm-ppc64 is now empty!

Signed-off-by: Paul Mackerras <paulus@samba.org>

This involves some minor changes: a few unused functions that the
ppc32 pci.c provides are no longer declared here or exported;
pcibios_assign_all_busses now just refers to the pci_assign_all_buses
variable on both 32-bit and 64-bit; pcibios_scan_all_fns is now
just 0 instead of a function that always returns 0 on 64-bit.

Signed-off-by: Paul Mackerras <paulus@samba.org>

For these, I have just done the lame-o merge where the file ends up
looking like:

	#ifndef CONFIG_PPC64
	#include <asm-ppc/foo.h>
	#else
	... contents from asm-ppc64/foo.h
	#endif

so nothing has changed, really, except that we reduce include/asm-ppc64
a bit more.

Signed-off-by: Paul Mackerras <paulus@samba.org>

With the new powerpc architecture we don't seem to be able to disable huge
pages anymore.

    mm/built-in.o(.toc1+0xae0): undefined reference to `HPAGE_SHIFT'
    make: *** [.tmp_vmlinux1] Error 1

We seem to need to define HPAGE_SHIFT to something when HUGETLB_PAGE isn't
defined.  This patch defines it to PAGE_SHIFT when we have no support.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>