[PATCH] powerpc: fix for hugepage areas straddling 4GB boundary

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>

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 9250f14be8efcc9e8c1001f63208b90e9707ecc0..f867bba893caf86a8fdaa48019b1d86782f06c66 100644 (file)
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -287,15 +287,15 @@ static int open_high_hpage_areas(struct mm_struct *mm, u16 newareas)
 
 int prepare_hugepage_range(unsigned long addr, unsigned long len)
 {
-       int err;
+       int err = 0;
 
        if ( (addr+len) < addr )
                return -EINVAL;
 
-       if ((addr + len) < 0x100000000UL)
+       if (addr < 0x100000000UL)
                err = open_low_hpage_areas(current->mm,
                                          LOW_ESID_MASK(addr, len));
-       else
+       if ((addr + len) >= 0x100000000UL)
                err = open_high_hpage_areas(current->mm,
                                            HTLB_AREA_MASK(addr, len));
        if (err) {

diff --git a/include/asm-powerpc/page_64.h b/include/asm-powerpc/page_64.h
index 1e6e7846824fca9f0d23fe7f6384a9072f38faaf..58a3dd9a79ec3f957f46ed5e84b768c65d44ecef 100644 (file)
--- a/include/asm-powerpc/page_64.h
+++ b/include/asm-powerpc/page_64.h
@@ -135,9 +135,9 @@ extern unsigned int HPAGE_SHIFT;
 
 #define in_hugepage_area(context, addr) \
        (cpu_has_feature(CPU_FTR_16M_PAGE) && \
-        ( ((1 << GET_HTLB_AREA(addr)) & (context).high_htlb_areas) || \
-          ( ((addr) < 0x100000000L) && \
-            ((1 << GET_ESID(addr)) & (context).low_htlb_areas) ) ) )
+        ( ( (addr) >= 0x100000000UL) \
+          ? ((1 << GET_HTLB_AREA(addr)) & (context).high_htlb_areas) \
+          : ((1 << GET_ESID(addr)) & (context).low_htlb_areas) ) )
 
 #else /* !CONFIG_HUGETLB_PAGE */