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) */
  22 static 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
  47 static 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
  59 static 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
  65 static 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
  73 static 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
 103 static inline void
 104 pmd_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
 124 static inline pgtable_t
 125 pte_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
 137 static inline pte_t *
 138 pte_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
 144 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 145 {
 146         free_page((unsigned long)pte);
 147 }
 148
 149 static 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