arch/hexagon/include/asm/pgalloc.h

   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
  29 extern unsigned long long kmap_generation;
  30
  31 /*
  32  * Page table creation interface
  33  */
  34 static 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
  57 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  58 {
  59         free_page((unsigned long) pgd);
  60 }
  61
  62 static 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_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 */
  78 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
  79                                           unsigned long address)
  80 {
  81         gfp_t flags =  GFP_KERNEL | __GFP_ZERO;
  82         return (pte_t *) __get_free_page(flags);
  83 }
  84
  85 static inline void pte_free(struct mm_struct *mm, struct page *pte)
  86 {
  87         pgtable_page_dtor(pte);
  88         __free_page(pte);
  89 }
  90
  91 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
  92 {
  93         free_page((unsigned long)pte);
  94 }
  95
  96 static 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  */
 116 static 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)          \
 143 do {                                            \
 144         pgtable_page_dtor((pte));               \
 145         tlb_remove_page((tlb), (pte));          \
 146 } while (0)
 147
 148 #endif