arch/powerpc/mm/pgtable-book3e.c

   1 /*
   2  * Copyright 2005, Paul Mackerras, IBM Corporation.
   3  * Copyright 2009, Benjamin Herrenschmidt, IBM Corporation.
   4  * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/memblock.h>
  14 #include <asm/pgalloc.h>
  15 #include <asm/tlb.h>
  16 #include <asm/dma.h>
  17
  18 #include "mmu_decl.h"
  19
  20 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  21 /*
  22  * On Book3E CPUs, the vmemmap is currently mapped in the top half of
  23  * the vmalloc space using normal page tables, though the size of
  24  * pages encoded in the PTEs can be different
  25  */
  26 int __meminit vmemmap_create_mapping(unsigned long start,
  27                                      unsigned long page_size,
  28                                      unsigned long phys)
  29 {
  30         /* Create a PTE encoding without page size */
  31         unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
  32                 _PAGE_KERNEL_RW;
  33
  34         /* PTEs only contain page size encodings up to 32M */
  35         BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);
  36
  37         /* Encode the size in the PTE */
  38         flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;
  39
  40         /* For each PTE for that area, map things. Note that we don't
  41          * increment phys because all PTEs are of the large size and
  42          * thus must have the low bits clear
  43          */
  44         for (i = 0; i < page_size; i += PAGE_SIZE)
  45                 BUG_ON(map_kernel_page(start + i, phys, flags));
  46
  47         return 0;
  48 }
  49
  50 #ifdef CONFIG_MEMORY_HOTPLUG
  51 void vmemmap_remove_mapping(unsigned long start,
  52                             unsigned long page_size)
  53 {
  54 }
  55 #endif
  56 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
  57
  58 static __ref void *early_alloc_pgtable(unsigned long size)
  59 {
  60         void *pt;
  61
  62         pt = __va(memblock_alloc_base(size, size, __pa(MAX_DMA_ADDRESS)));
  63         memset(pt, 0, size);
  64
  65         return pt;
  66 }
  67
  68 /*
  69  * map_kernel_page currently only called by __ioremap
  70  * map_kernel_page adds an entry to the ioremap page table
  71  * and adds an entry to the HPT, possibly bolting it
  72  */
  73 int map_kernel_page(unsigned long ea, unsigned long pa, unsigned long flags)
  74 {
  75         pgd_t *pgdp;
  76         pud_t *pudp;
  77         pmd_t *pmdp;
  78         pte_t *ptep;
  79
  80         BUILD_BUG_ON(TASK_SIZE_USER64 > PGTABLE_RANGE);
  81         if (slab_is_available()) {
  82                 pgdp = pgd_offset_k(ea);
  83                 pudp = pud_alloc(&init_mm, pgdp, ea);
  84                 if (!pudp)
  85                         return -ENOMEM;
  86                 pmdp = pmd_alloc(&init_mm, pudp, ea);
  87                 if (!pmdp)
  88                         return -ENOMEM;
  89                 ptep = pte_alloc_kernel(pmdp, ea);
  90                 if (!ptep)
  91                         return -ENOMEM;
  92                 set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
  93                                                           __pgprot(flags)));
  94         } else {
  95                 pgdp = pgd_offset_k(ea);
  96 #ifndef __PAGETABLE_PUD_FOLDED
  97                 if (pgd_none(*pgdp)) {
  98                         pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
  99                         BUG_ON(pudp == NULL);
 100                         pgd_populate(&init_mm, pgdp, pudp);
 101                 }
 102 #endif /* !__PAGETABLE_PUD_FOLDED */
 103                 pudp = pud_offset(pgdp, ea);
 104                 if (pud_none(*pudp)) {
 105                         pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
 106                         BUG_ON(pmdp == NULL);
 107                         pud_populate(&init_mm, pudp, pmdp);
 108                 }
 109                 pmdp = pmd_offset(pudp, ea);
 110                 if (!pmd_present(*pmdp)) {
 111                         ptep = early_alloc_pgtable(PAGE_SIZE);
 112                         BUG_ON(ptep == NULL);
 113                         pmd_populate_kernel(&init_mm, pmdp, ptep);
 114                 }
 115                 ptep = pte_offset_kernel(pmdp, ea);
 116                 set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
 117                                                           __pgprot(flags)));
 118         }
 119
 120         smp_wmb();
 121         return 0;
 122 }