1/*
  2 * Page table support for the Hexagon architecture
  3 *
  4 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 and
  8 * only version 2 as published by the Free Software Foundation.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 * GNU General Public License for more details.
 14 *
 15 * You should have received a copy of the GNU General Public License
 16 * along with this program; if not, write to the Free Software
 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 18 * 02110-1301, USA.
 19 */
 20
 21#ifndef _ASM_PGALLOC_H
 22#define _ASM_PGALLOC_H
 23
 24#include <asm/mem-layout.h>
 25#include <asm/atomic.h>
 26
 27#define check_pgt_cache() do {} while (0)
 28
 29extern unsigned long long kmap_generation;
 30
 31/*
 32 * Page table creation interface
 33 */
 34static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 35{
 36	pgd_t *pgd;
 37
 38	pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 39
 40	/*
 41	 * There may be better ways to do this, but to ensure
 42	 * that new address spaces always contain the kernel
 43	 * base mapping, and to ensure that the user area is
 44	 * initially marked invalid, initialize the new map
 45	 * map with a copy of the kernel's persistent map.
 46	 */
 47
 48	memcpy(pgd, swapper_pg_dir, PTRS_PER_PGD*sizeof(pgd_t *));
 49	mm->context.generation = kmap_generation;
 50
 51	/* Physical version is what is passed to virtual machine on switch */
 52	mm->context.ptbase = __pa(pgd);
 53
 54	return pgd;
 55}
 56
 57static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 58{
 59	free_page((unsigned long) pgd);
 60}
 61
 62static inline struct page *pte_alloc_one(struct mm_struct *mm,
 63					 unsigned long address)
 64{
 65	struct page *pte;
 66
 67	pte = alloc_page(GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO);
 68
 69	if (pte)
 70		pgtable_page_ctor(pte);
 71
 72	return pte;
 73}
 74
 75/* _kernel variant gets to use a different allocator */
 76static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
 77					  unsigned long address)
 78{
 79	gfp_t flags =  GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO;
 80	return (pte_t *) __get_free_page(flags);
 81}
 82
 83static inline void pte_free(struct mm_struct *mm, struct page *pte)
 84{
 85	pgtable_page_dtor(pte);
 86	__free_page(pte);
 87}
 88
 89static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 90{
 91	free_page((unsigned long)pte);
 92}
 93
 94static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 95				pgtable_t pte)
 96{
 97	/*
 98	 * Conveniently, zero in 3 LSB means indirect 4K page table.
 99	 * Not so convenient when you're trying to vary the page size.
100	 */
101	set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) |
102		HEXAGON_L1_PTE_SIZE));
103}
104
105/*
106 * Other architectures seem to have ways of making all processes
107 * share the same pmd's for their kernel mappings, but the v0.3
108 * Hexagon VM spec has a "monolithic" L1 table for user and kernel
109 * segments.  We track "generations" of the kernel map to minimize
110 * overhead, and update the "slave" copies of the kernel mappings
111 * as part of switch_mm.  However, we still need to update the
112 * kernel map of the active thread who's calling pmd_populate_kernel...
113 */
114static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
115				       pte_t *pte)
116{
117	extern spinlock_t kmap_gen_lock;
118	pmd_t *ppmd;
119	int pmdindex;
120
121	spin_lock(&kmap_gen_lock);
122	kmap_generation++;
123	mm->context.generation = kmap_generation;
124	current->active_mm->context.generation = kmap_generation;
125	spin_unlock(&kmap_gen_lock);
126
127	set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
128
129	/*
130	 * Now the "slave" copy of the current thread.
131	 * This is pointer arithmetic, not byte addresses!
132	 */
133	pmdindex = (pgd_t *)pmd - mm->pgd;
134	ppmd = (pmd_t *)current->active_mm->pgd + pmdindex;
135	set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
136	if (pmdindex > max_kernel_seg)
137		max_kernel_seg = pmdindex;
138}
139
140#define __pte_free_tlb(tlb, pte, addr)		\
141do {						\
142	pgtable_page_dtor((pte));		\
143	tlb_remove_page((tlb), (pte));		\
144} while (0)
145
146#endif