[S390] System z large page support.

This adds hugetlbfs support on System z, using both hardware large page
support if available and software large page emulation on older hardware.
Shared (large) page tables are implemented in software emulation mode,
by using page->index of the first tail page from a compound large page
to store page table information.

Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/asm-s390/pgtable.h b/include/asm-s390/pgtable.h
index f8347ce9c5a1..fd336f2e2a7a 100644
--- a/include/asm-s390/pgtable.h
+++ b/include/asm-s390/pgtable.h
@@ -234,6 +234,15 @@ extern char empty_zero_page[PAGE_SIZE];
 #define _PAGE_TYPE_EX_RW        0x002
 
 /*
+ * Only four types for huge pages, using the invalid bit and protection bit
+ * of a segment table entry.
+ */
+#define _HPAGE_TYPE_EMPTY       0x020   /* _SEGMENT_ENTRY_INV */
+#define _HPAGE_TYPE_NONE        0x220
+#define _HPAGE_TYPE_RO          0x200   /* _SEGMENT_ENTRY_RO  */
+#define _HPAGE_TYPE_RW          0x000
+
+/*
  * PTE type bits are rather complicated. handle_pte_fault uses pte_present,
  * pte_none and pte_file to find out the pte type WITHOUT holding the page
  * table lock. ptep_clear_flush on the other hand uses ptep_clear_flush to
@@ -325,6 +334,9 @@ extern char empty_zero_page[PAGE_SIZE];
 #define _SEGMENT_ENTRY          (0)
 #define _SEGMENT_ENTRY_EMPTY    (_SEGMENT_ENTRY_INV)
 
+#define _SEGMENT_ENTRY_LARGE    0x400   /* STE-format control, large page   */
+#define _SEGMENT_ENTRY_CO       0x100   /* change-recording override   */
+
 #endif /* __s390x__ */
 
 /*