LXR linux/arch/parisc/include/asm/pgalloc.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_PGALLOC_H
   3#define _ASM_PGALLOC_H
   4
   5#include <linux/gfp.h>
   6#include <linux/mm.h>
   7#include <linux/threads.h>
   8#include <asm/processor.h>
   9#include <asm/fixmap.h>
  10
  11#include <asm/cache.h>
  12
  13/* Allocate the top level pgd (page directory)
  14 *
  15 * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we
  16 * allocate the first pmd adjacent to the pgd.  This means that we can
  17 * subtract a constant offset to get to it.  The pmd and pgd sizes are
  18 * arranged so that a single pmd covers 4GB (giving a full 64-bit
  19 * process access to 8TB) so our lookups are effectively L2 for the
  20 * first 4GB of the kernel (i.e. for all ILP32 processes and all the
  21 * kernel for machines with under 4GB of memory) */
  22static inline pgd_t *pgd_alloc(struct mm_struct *mm)
  23{
  24        pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL,
  25                                               PGD_ALLOC_ORDER);
  26        pgd_t *actual_pgd = pgd;
  27
  28        if (likely(pgd != NULL)) {
  29                memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER);
  30#if CONFIG_PGTABLE_LEVELS == 3
  31                actual_pgd += PTRS_PER_PGD;
  32                /* Populate first pmd with allocated memory.  We mark it
  33                 * with PxD_FLAG_ATTACHED as a signal to the system that this
  34                 * pmd entry may not be cleared. */
  35                __pgd_val_set(*actual_pgd, (PxD_FLAG_PRESENT | 
  36                                        PxD_FLAG_VALID | 
  37                                        PxD_FLAG_ATTACHED) 
  38                        + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT));
  39                /* The first pmd entry also is marked with PxD_FLAG_ATTACHED as
  40                 * a signal that this pmd may not be freed */
  41                __pgd_val_set(*pgd, PxD_FLAG_ATTACHED);
  42#endif
  43        }
  44        return actual_pgd;
  45}
  46
  47static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  48{
  49#if CONFIG_PGTABLE_LEVELS == 3
  50        pgd -= PTRS_PER_PGD;
  51#endif
  52        free_pages((unsigned long)pgd, PGD_ALLOC_ORDER);
  53}
  54
  55#if CONFIG_PGTABLE_LEVELS == 3
  56
  57/* Three Level Page Table Support for pmd's */
  58
  59static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
  60{
  61        __pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) +
  62                        (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT));
  63}
  64
  65static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
  66{
  67        pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER);
  68        if (pmd)
  69                memset(pmd, 0, PAGE_SIZE<<PMD_ORDER);
  70        return pmd;
  71}
  72
  73static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
  74{
  75        if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) {
  76                /*
  77                 * This is the permanent pmd attached to the pgd;
  78                 * cannot free it.
  79                 * Increment the counter to compensate for the decrement
  80                 * done by generic mm code.
  81                 */
  82                mm_inc_nr_pmds(mm);
  83                return;
  84        }
  85        free_pages((unsigned long)pmd, PMD_ORDER);
  86}
  87
  88#else
  89
  90/* Two Level Page Table Support for pmd's */
  91
  92/*
  93 * allocating and freeing a pmd is trivial: the 1-entry pmd is
  94 * inside the pgd, so has no extra memory associated with it.
  95 */
  96
  97#define pmd_alloc_one(mm, addr)         ({ BUG(); ((pmd_t *)2); })
  98#define pmd_free(mm, x)                 do { } while (0)
  99#define pgd_populate(mm, pmd, pte)      BUG()
 100
 101#endif
 102
 103static inline void
 104pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
 105{
 106#if CONFIG_PGTABLE_LEVELS == 3
 107        /* preserve the gateway marker if this is the beginning of
 108         * the permanent pmd */
 109        if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
 110                __pmd_val_set(*pmd, (PxD_FLAG_PRESENT |
 111                                 PxD_FLAG_VALID |
 112                                 PxD_FLAG_ATTACHED) 
 113                        + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
 114        else
 115#endif
 116                __pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) 
 117                        + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
 118}
 119
 120#define pmd_populate(mm, pmd, pte_page) \
 121        pmd_populate_kernel(mm, pmd, page_address(pte_page))
 122#define pmd_pgtable(pmd) pmd_page(pmd)
 123
 124static inline pgtable_t
 125pte_alloc_one(struct mm_struct *mm, unsigned long address)
 126{
 127        struct page *page = alloc_page(GFP_KERNEL|__GFP_ZERO);
 128        if (!page)
 129                return NULL;
 130        if (!pgtable_page_ctor(page)) {
 131                __free_page(page);
 132                return NULL;
 133        }
 134        return page;
 135}
 136
 137static inline pte_t *
 138pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
 139{
 140        pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
 141        return pte;
 142}
 143
 144static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 145{
 146        free_page((unsigned long)pte);
 147}
 148
 149static inline void pte_free(struct mm_struct *mm, struct page *pte)
 150{
 151        pgtable_page_dtor(pte);
 152        pte_free_kernel(mm, page_address(pte));
 153}
 154
 155#define check_pgt_cache()       do { } while (0)
 156
 157#endif
 158