1/*
  2 * Page table support for the Hexagon architecture
  3 *
  4 * Copyright (c) 2010-2011, The Linux Foundation. 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	if (!pte)
 69		return NULL;
 70	if (!pgtable_page_ctor(pte)) {
 71		__free_page(pte);
 72		return NULL;
 73	}
 74	return pte;
 75}
 76
 77/* _kernel variant gets to use a different allocator */
 78static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
 79					  unsigned long address)
 80{
 81	gfp_t flags =  GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO;
 82	return (pte_t *) __get_free_page(flags);
 83}
 84
 85static inline void pte_free(struct mm_struct *mm, struct page *pte)
 86{
 87	pgtable_page_dtor(pte);
 88	__free_page(pte);
 89}
 90
 91static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 92{
 93	free_page((unsigned long)pte);
 94}
 95
 96static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 97				pgtable_t pte)
 98{
 99	/*
100	 * Conveniently, zero in 3 LSB means indirect 4K page table.
101	 * Not so convenient when you're trying to vary the page size.
102	 */
103	set_pmd(pmd, __pmd(((unsigned long)page_to_pfn(pte) << PAGE_SHIFT) |
104		HEXAGON_L1_PTE_SIZE));
105}
106
107/*
108 * Other architectures seem to have ways of making all processes
109 * share the same pmd's for their kernel mappings, but the v0.3
110 * Hexagon VM spec has a "monolithic" L1 table for user and kernel
111 * segments.  We track "generations" of the kernel map to minimize
112 * overhead, and update the "slave" copies of the kernel mappings
113 * as part of switch_mm.  However, we still need to update the
114 * kernel map of the active thread who's calling pmd_populate_kernel...
115 */
116static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
117				       pte_t *pte)
118{
119	extern spinlock_t kmap_gen_lock;
120	pmd_t *ppmd;
121	int pmdindex;
122
123	spin_lock(&kmap_gen_lock);
124	kmap_generation++;
125	mm->context.generation = kmap_generation;
126	current->active_mm->context.generation = kmap_generation;
127	spin_unlock(&kmap_gen_lock);
128
129	set_pmd(pmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
130
131	/*
132	 * Now the "slave" copy of the current thread.
133	 * This is pointer arithmetic, not byte addresses!
134	 */
135	pmdindex = (pgd_t *)pmd - mm->pgd;
136	ppmd = (pmd_t *)current->active_mm->pgd + pmdindex;
137	set_pmd(ppmd, __pmd(((unsigned long)__pa(pte)) | HEXAGON_L1_PTE_SIZE));
138	if (pmdindex > max_kernel_seg)
139		max_kernel_seg = pmdindex;
140}
141
142#define __pte_free_tlb(tlb, pte, addr)		\
143do {						\
144	pgtable_page_dtor((pte));		\
145	tlb_remove_page((tlb), (pte));		\
146} while (0)
147
148#endif