[PATCH] powerpc: More hugepage boundary case fixes

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 7d24f0b8a5 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>

arch/powerpc/mm/hugetlbpage.c

@@ -295,7 +295,7 @@ int prepare_hugepage_range(unsigned long addr, unsigned long len)
 	if (addr < 0x100000000UL)
 		err = open_low_hpage_areas(current->mm,
 					  LOW_ESID_MASK(addr, len));
-	if ((addr + len) >= 0x100000000UL)
+	if ((addr + len) > 0x100000000UL)
 		err = open_high_hpage_areas(current->mm,
 					    HTLB_AREA_MASK(addr, len));
 	if (err) {