s390/mm: cleanup page table definitions

Improve the encoding of the different pte types and the naming of the
page, segment table and region table bits. Due to the different pte
encoding the hugetlbfs primitives need to be adapted as well. To improve
compatability with common code make the huge ptes use the encoding of
normal ptes. The conversion between the pte and pmd encoding for a huge
pte is done with set_huge_pte_at and huge_ptep_get.
Overall the code is now easier to understand.

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

1 files changed, 95 insertions, 9 deletions

diff --git a/arch/s390/mm/hugetlbpage.c b/arch/s390/mm/hugetlbpage.c
index 121089d..b0bd0ae 100644
--- a/arch/s390/mm/hugetlbpage.c
+++ b/arch/s390/mm/hugetlbpage.c
@@ -8,21 +8,107 @@
 #include <linux/mm.h>
 #include <linux/hugetlb.h>
 
+static inline pmd_t __pte_to_pmd(pte_t pte)
+{
+	int none, prot;
+	pmd_t pmd;
+
+	/*
+	 * Convert encoding	  pte bits	  pmd bits
+	 *			.IR.....wdtp	..R...I.....
+	 * empty		.10.....0000 -> ..0...1.....
+	 * prot-none, clean	.11.....0001 -> ..1...1.....
+	 * prot-none, dirty	.10.....0101 -> ..1...1.....
+	 * read-only, clean	.01.....0001 -> ..1...0.....
+	 * read-only, dirty	.01.....0101 -> ..1...0.....
+	 * read-write, clean	.01.....1001 -> ..0...0.....
+	 * read-write, dirty	.00.....1101 -> ..0...0.....
+	 * Huge ptes are dirty by definition, a clean pte is made dirty
+	 * by the conversion.
+	 */
+	if (pte_present(pte)) {
+		pmd_val(pmd) = pte_val(pte) & PAGE_MASK;
+		if (pte_val(pte) & _PAGE_INVALID)
+			pmd_val(pmd) |= _SEGMENT_ENTRY_INVALID;
+		none = (pte_val(pte) & _PAGE_PRESENT) &&
+			(pte_val(pte) & _PAGE_INVALID);
+		prot = (pte_val(pte) & _PAGE_PROTECT);
+		if (prot || none)
+			pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;
+	} else
+		pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;
+	return pmd;
+}
+
+static inline pte_t __pmd_to_pte(pmd_t pmd)
+{
+	pte_t pte;
+
+	/*
+	 * Convert encoding	  pmd bits	  pte bits
+	 *			..R...I.....	.IR.....wdtp
+	 * empty		..0...1..... -> .10.....0000
+	 * prot-none, young	..1...1..... -> .10.....0101
+	 * read-only, young	..1...0..... -> .01.....0101
+	 * read-write, young	..0...0..... -> .00.....1101
+	 * Huge ptes are dirty by definition
+	 */
+	if (pmd_present(pmd)) {
+		pte_val(pte) = _PAGE_PRESENT | _PAGE_LARGE | _PAGE_DIRTY |
+			(pmd_val(pmd) & PAGE_MASK);
+		if (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID)
+			pte_val(pte) |= _PAGE_INVALID;
+		else {
+			if (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT)
+				pte_val(pte) |= _PAGE_PROTECT;
+			else
+				pte_val(pte) |= _PAGE_WRITE;
+		}
+	} else
+		pte_val(pte) = _PAGE_INVALID;
+	return pte;
+}
 
 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
-				   pte_t *pteptr, pte_t pteval)
+		     pte_t *ptep, pte_t pte)
 {
-	pmd_t *pmdp = (pmd_t *) pteptr;
-	unsigned long mask;
+	pmd_t pmd;
 
+	pmd = __pte_to_pmd(pte);
 	if (!MACHINE_HAS_HPAGE) {
-		pteptr = (pte_t *) pte_page(pteval)[1].index;
-		mask = pte_val(pteval) &
-				(_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
-		pte_val(pteval) = (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
+		pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;
+		pmd_val(pmd) |= pte_page(pte)[1].index;
+	} else
+		pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO;
+	*(pmd_t *) ptep = pmd;
+}
+
+pte_t huge_ptep_get(pte_t *ptep)
+{
+	unsigned long origin;
+	pmd_t pmd;
+
+	pmd = *(pmd_t *) ptep;
+	if (!MACHINE_HAS_HPAGE && pmd_present(pmd)) {
+		origin = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN;
+		pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;
+		pmd_val(pmd) |= *(unsigned long *) origin;
 	}
+	return __pmd_to_pte(pmd);
+}
 
-	pmd_val(*pmdp) = pte_val(pteval);
+pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
+			      unsigned long addr, pte_t *ptep)
+{
+	pmd_t *pmdp = (pmd_t *) ptep;
+	pte_t pte = huge_ptep_get(ptep);
+
+	if (MACHINE_HAS_IDTE)
+		__pmd_idte(addr, pmdp);
+	else
+		__pmd_csp(pmdp);
+	pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
+	return pte;
 }
 
 int arch_prepare_hugepage(struct page *page)
@@ -58,7 +144,7 @@ void arch_release_hugepage(struct page *page)
 	ptep = (pte_t *) page[1].index;
 	if (!ptep)
 		return;
-	clear_table((unsigned long *) ptep, _PAGE_TYPE_EMPTY,
+	clear_table((unsigned long *) ptep, _PAGE_INVALID,
 		    PTRS_PER_PTE * sizeof(pte_t));
 	page_table_free(&init_mm, (unsigned long *) ptep);
 	page[1].index = 0;