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 #define __HAVE_ARCH_PMD_ALLOC_ONE
  14 #define __HAVE_ARCH_PMD_FREE
  15 #define __HAVE_ARCH_PGD_FREE
  16 #include <asm-generic/pgalloc.h>
  17
  18 /* Allocate the top level pgd (page directory)
  19  *
  20  * Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we
  21  * allocate the first pmd adjacent to the pgd.  This means that we can
  22  * subtract a constant offset to get to it.  The pmd and pgd sizes are
  23  * arranged so that a single pmd covers 4GB (giving a full 64-bit
  24  * process access to 8TB) so our lookups are effectively L2 for the
  25  * first 4GB of the kernel (i.e. for all ILP32 processes and all the
  26  * kernel for machines with under 4GB of memory) */
  27 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
  28 {
  29         pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL,
  30                                                PGD_ALLOC_ORDER);
  31         pgd_t *actual_pgd = pgd;
  32
  33         if (likely(pgd != NULL)) {
  34                 memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER);
  35 #if CONFIG_PGTABLE_LEVELS == 3
  36                 actual_pgd += PTRS_PER_PGD;
  37                 /* Populate first pmd with allocated memory.  We mark it
  38                  * with PxD_FLAG_ATTACHED as a signal to the system that this
  39                  * pmd entry may not be cleared. */
  40                 set_pgd(actual_pgd, __pgd((PxD_FLAG_PRESENT |
  41                                         PxD_FLAG_VALID |
  42                                         PxD_FLAG_ATTACHED)
  43                         + (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT)));
  44                 /* The first pmd entry also is marked with PxD_FLAG_ATTACHED as
  45                  * a signal that this pmd may not be freed */
  46                 set_pgd(pgd, __pgd(PxD_FLAG_ATTACHED));
  47 #endif
  48         }
  49         spin_lock_init(pgd_spinlock(actual_pgd));
  50         return actual_pgd;
  51 }
  52
  53 static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  54 {
  55 #if CONFIG_PGTABLE_LEVELS == 3
  56         pgd -= PTRS_PER_PGD;
  57 #endif
  58         free_pages((unsigned long)pgd, PGD_ALLOC_ORDER);
  59 }
  60
  61 #if CONFIG_PGTABLE_LEVELS == 3
  62
  63 /* Three Level Page Table Support for pmd's */
  64
  65 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
  66 {
  67         set_pud(pud, __pud((PxD_FLAG_PRESENT | PxD_FLAG_VALID) +
  68                         (__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT)));
  69 }
  70
  71 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
  72 {
  73         return (pmd_t *)__get_free_pages(GFP_PGTABLE_KERNEL, PMD_ORDER);
  74 }
  75
  76 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
  77 {
  78         if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) {
  79                 /*
  80                  * This is the permanent pmd attached to the pgd;
  81                  * cannot free it.
  82                  * Increment the counter to compensate for the decrement
  83                  * done by generic mm code.
  84                  */
  85                 mm_inc_nr_pmds(mm);
  86                 return;
  87         }
  88         free_pages((unsigned long)pmd, PMD_ORDER);
  89 }
  90
  91 #endif
  92
  93 static inline void
  94 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
  95 {
  96 #if CONFIG_PGTABLE_LEVELS == 3
  97         /* preserve the gateway marker if this is the beginning of
  98          * the permanent pmd */
  99         if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
 100                 set_pmd(pmd, __pmd((PxD_FLAG_PRESENT |
 101                                 PxD_FLAG_VALID |
 102                                 PxD_FLAG_ATTACHED)
 103                         + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)));
 104         else
 105 #endif
 106                 set_pmd(pmd, __pmd((PxD_FLAG_PRESENT | PxD_FLAG_VALID)
 107                         + (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT)));
 108 }
 109
 110 #define pmd_populate(mm, pmd, pte_page) \
 111         pmd_populate_kernel(mm, pmd, page_address(pte_page))
 112 #define pmd_pgtable(pmd) pmd_page(pmd)
 113
 114 #endif