s390/mm,vmem: use 2GB frames for identity mapping

Use 2GB frames for indentity mapping if EDAT2 is
available to reduce TLB pressure.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/pgtable.h

@@ -345,6 +345,8 @@ extern unsigned long MODULES_END;
 #define _REGION3_ENTRY		(_REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_LENGTH)
 #define _REGION3_ENTRY_EMPTY	(_REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_INV)
 
+#define _REGION3_ENTRY_LARGE	0x400	/* RTTE-format control, large page  */
+
 /* Bits in the segment table entry */
 #define _SEGMENT_ENTRY_ORIGIN	~0x7ffUL/* segment table origin		    */
 #define _SEGMENT_ENTRY_RO	0x200	/* page protection bit		    */
@@ -444,6 +446,7 @@ static inline int pgd_bad(pgd_t pgd)     { return 0; }
 
 static inline int pud_present(pud_t pud) { return 1; }
 static inline int pud_none(pud_t pud)	 { return 0; }
+static inline int pud_large(pud_t pud)	 { return 0; }
 static inline int pud_bad(pud_t pud)	 { return 0; }
 
 #else /* CONFIG_64BIT */
@@ -489,6 +492,13 @@ static inline int pud_none(pud_t pud)
 	return (pud_val(pud) & _REGION_ENTRY_INV) != 0UL;
 }
 
+static inline int pud_large(pud_t pud)
+{
+	if ((pud_val(pud) & _REGION_ENTRY_TYPE_MASK) != _REGION_ENTRY_TYPE_R3)
+		return 0;
+	return !!(pud_val(pud) & _REGION3_ENTRY_LARGE);
+}
+
 static inline int pud_bad(pud_t pud)
 {
 	/*

arch/s390/mm/dump_pagetables.c

@@ -150,6 +150,7 @@ static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
 static void walk_pud_level(struct seq_file *m, struct pg_state *st,
 			   pgd_t *pgd, unsigned long addr)
 {
+	unsigned int prot;
 	pud_t *pud;
 	int i;
 
@@ -157,6 +158,10 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st,
 		st->current_address = addr;
 		pud = pud_offset(pgd, addr);
 		if (!pud_none(*pud))
+			if (pud_large(*pud)) {
+				prot = pud_val(*pud) & _PAGE_RO;
+				note_page(m, st, prot, 2);
+			} else
 				walk_pmd_level(m, st, pud, addr);
 		else
 			note_page(m, st, _PAGE_INVALID, 2);

arch/s390/mm/pageattr.c

@@ -19,7 +19,7 @@ static pte_t *walk_page_table(unsigned long addr)
 	if (pgd_none(*pgdp))
 		return NULL;
 	pudp = pud_offset(pgdp, addr);
-	if (pud_none(*pudp))
+	if (pud_none(*pudp) || pud_large(*pudp))
 		return NULL;
 	pmdp = pmd_offset(pudp, addr);
 	if (pmd_none(*pmdp) || pmd_large(*pmdp))

arch/s390/mm/vmem.c

@@ -89,6 +89,7 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
 	int ret = -ENOMEM;
 
 	while (address < end) {
+		pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
 		pg_dir = pgd_offset_k(address);
 		if (pgd_none(*pg_dir)) {
 			pu_dir = vmem_pud_alloc();
@@ -96,18 +97,24 @@ static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
 				goto out;
 			pgd_populate(&init_mm, pg_dir, pu_dir);
 		}
-
 		pu_dir = pud_offset(pg_dir, address);
+#if defined(CONFIG_64BIT) && !defined(CONFIG_DEBUG_PAGEALLOC)
+		if (MACHINE_HAS_EDAT2 && pud_none(*pu_dir) && address &&
+		    !(address & ~PUD_MASK) && (address + PUD_SIZE <= end)) {
+			pte_val(pte) |= _REGION3_ENTRY_LARGE;
+			pte_val(pte) |= _REGION_ENTRY_TYPE_R3;
+			pud_val(*pu_dir) = pte_val(pte);
+			address += PUD_SIZE;
+			continue;
+		}
+#endif
 		if (pud_none(*pu_dir)) {
 			pm_dir = vmem_pmd_alloc();
 			if (!pm_dir)
 				goto out;
 			pud_populate(&init_mm, pu_dir, pm_dir);
 		}
-
-		pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
 		pm_dir = pmd_offset(pu_dir, address);
-
 #if defined(CONFIG_64BIT) && !defined(CONFIG_DEBUG_PAGEALLOC)
 		if (MACHINE_HAS_EDAT1 && pmd_none(*pm_dir) && address &&
 		    !(address & ~PMD_MASK) && (address + PMD_SIZE <= end)) {
@@ -160,6 +167,11 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
 			address += PUD_SIZE;
 			continue;
 		}
+		if (pud_large(*pu_dir)) {
+			pud_clear(pu_dir);
+			address += PUD_SIZE;
+			continue;
+		}
 		pm_dir = pmd_offset(pu_dir, address);
 		if (pmd_none(*pm_dir)) {
 			address += PMD_SIZE;