[S390] refactor page table functions for better pgste support

Rework the architecture page table functions to access the bits in the
page table extension array (pgste). There are a number of changes:
1) Fix missing pgste update if the attach_count for the mm is <= 1.
2) For every operation that affects the invalid bit in the pte or the
   rcp byte in the pgste the pcl lock needs to be acquired. The function
   pgste_get_lock gets the pcl lock and returns the current pgste value
   for a pte pointer. The function pgste_set_unlock stores the pgste
   and releases the lock. Between these two calls the bits in the pgste
   can be shuffled.
3) Define two software bits in the pte _PAGE_SWR and _PAGE_SWC to avoid
   calling SetPageDirty and SetPageReferenced from pgtable.h. If the
   host reference backup bit or the host change backup bit has been
   set the dirty/referenced state is transfered to the pte. The common
   code will pick up the state from the pte.
4) Add ptep_modify_prot_start and ptep_modify_prot_commit for mprotect.
5) Remove pgd_populate_kernel, pud_populate_kernel, pmd_populate_kernel
   pgd_clear_kernel, pud_clear_kernel, pmd_clear_kernel and ptep_invalidate.
6) Rename kvm_s390_test_and_clear_page_dirty to
   ptep_test_and_clear_user_dirty and add ptep_test_and_clear_user_young.
7) Define mm_exclusive() and mm_has_pgste() helper to improve readability.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 81ee2776088..accb372ddc7 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -90,6 +90,7 @@ static inline void copy_page(void *to, void *from)
  */
 
 typedef struct { unsigned long pgprot; } pgprot_t;
+typedef struct { unsigned long pgste; } pgste_t;
 typedef struct { unsigned long pte; } pte_t;
 typedef struct { unsigned long pmd; } pmd_t;
 typedef struct { unsigned long pud; } pud_t;
@@ -97,13 +98,16 @@ typedef struct { unsigned long pgd; } pgd_t;
 typedef pte_t *pgtable_t;
 
 #define pgprot_val(x)	((x).pgprot)
+#define pgste_val(x)	((x).pgste)
 #define pte_val(x)	((x).pte)
 #define pmd_val(x)	((x).pmd)
 #define pud_val(x)	((x).pud)
 #define pgd_val(x)      ((x).pgd)
 
+#define __pgste(x)	((pgste_t) { (x) } )
 #define __pte(x)        ((pte_t) { (x) } )
 #define __pmd(x)        ((pmd_t) { (x) } )
+#define __pud(x)	((pud_t) { (x) } )
 #define __pgd(x)        ((pgd_t) { (x) } )
 #define __pgprot(x)     ((pgprot_t) { (x) } )