s390/mm: fix pmd_huge() usage for kernel mapping

pmd_huge() will always return 0 on !HUGETLBFS, however we use that helper
function when walking the kernel page tables to decide if we have a
1MB page frame or not.
Since we create 1MB frames for the kernel 1:1 mapping independently of
HUGETLBFS this can lead to incorrect storage accesses since the code
can assume that we have a pointer to a page table instead of a pointer
to a 1MB frame.

Fix this by adding a pmd_large() primitive like other architectures have
it already and remove all references to HUGETLBFS/HUGETLBPAGE from the
code that walks kernel page tables.

Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 979fe3dc0788..75b91bb772bd 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -507,6 +507,15 @@ static inline int pmd_none(pmd_t pmd)
 	return (pmd_val(pmd) & _SEGMENT_ENTRY_INV) != 0UL;
 }
 
+static inline int pmd_large(pmd_t pmd)
+{
+#ifdef CONFIG_64BIT
+	return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
+#else
+	return 0;
+#endif
+}
+
 static inline int pmd_bad(pmd_t pmd)
 {
 	unsigned long mask = ~_SEGMENT_ENTRY_ORIGIN & ~_SEGMENT_ENTRY_INV;