1/*
  2 *  IBM System z Huge TLB Page Support for Kernel.
  3 *
  4 *    Copyright 2007 IBM Corp.
  5 *    Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
  6 */
  7
  8#include <linux/mm.h>
  9#include <linux/hugetlb.h>
 10
 11
 12void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 13				   pte_t *pteptr, pte_t pteval)
 14{
 15	pmd_t *pmdp = (pmd_t *) pteptr;
 16	unsigned long mask;
 17
 18	if (!MACHINE_HAS_HPAGE) {
 19		pteptr = (pte_t *) pte_page(pteval)[1].index;
 20		mask = pte_val(pteval) &
 21				(_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
 22		pte_val(pteval) = (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
 23	}
 24
 25	pmd_val(*pmdp) = pte_val(pteval);
 26}
 27
 28int arch_prepare_hugepage(struct page *page)
 29{
 30	unsigned long addr = page_to_phys(page);
 31	pte_t pte;
 32	pte_t *ptep;
 33	int i;
 34
 35	if (MACHINE_HAS_HPAGE)
 36		return 0;
 37
 38	ptep = (pte_t *) pte_alloc_one(&init_mm, addr);
 39	if (!ptep)
 40		return -ENOMEM;
 41
 42	pte = mk_pte(page, PAGE_RW);
 43	for (i = 0; i < PTRS_PER_PTE; i++) {
 44		set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
 45		pte_val(pte) += PAGE_SIZE;
 46	}
 47	page[1].index = (unsigned long) ptep;
 48	return 0;
 49}
 50
 51void arch_release_hugepage(struct page *page)
 52{
 53	pte_t *ptep;
 54
 55	if (MACHINE_HAS_HPAGE)
 56		return;
 57
 58	ptep = (pte_t *) page[1].index;
 59	if (!ptep)
 60		return;
 61	clear_table((unsigned long *) ptep, _PAGE_TYPE_EMPTY,
 62		    PTRS_PER_PTE * sizeof(pte_t));
 63	page_table_free(&init_mm, (unsigned long *) ptep);
 64	page[1].index = 0;
 65}
 66
 67pte_t *huge_pte_alloc(struct mm_struct *mm,
 68			unsigned long addr, unsigned long sz)
 69{
 70	pgd_t *pgdp;
 71	pud_t *pudp;
 72	pmd_t *pmdp = NULL;
 73
 74	pgdp = pgd_offset(mm, addr);
 75	pudp = pud_alloc(mm, pgdp, addr);
 76	if (pudp)
 77		pmdp = pmd_alloc(mm, pudp, addr);
 78	return (pte_t *) pmdp;
 79}
 80
 81pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 82{
 83	pgd_t *pgdp;
 84	pud_t *pudp;
 85	pmd_t *pmdp = NULL;
 86
 87	pgdp = pgd_offset(mm, addr);
 88	if (pgd_present(*pgdp)) {
 89		pudp = pud_offset(pgdp, addr);
 90		if (pud_present(*pudp))
 91			pmdp = pmd_offset(pudp, addr);
 92	}
 93	return (pte_t *) pmdp;
 94}
 95
 96int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 97{
 98	return 0;
 99}
100
101struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
102			      int write)
103{
104	return ERR_PTR(-EINVAL);
105}
106
107int pmd_huge(pmd_t pmd)
108{
109	if (!MACHINE_HAS_HPAGE)
110		return 0;
111
112	return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
113}
114
115int pud_huge(pud_t pud)
116{
117	return 0;
118}
119
120struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
121			     pmd_t *pmdp, int write)
122{
123	struct page *page;
124
125	if (!MACHINE_HAS_HPAGE)
126		return NULL;
127
128	page = pmd_page(*pmdp);
129	if (page)
130		page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
131	return page;
132}