LXR linux/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 */
  26int __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
  51void vmemmap_remove_mapping(unsigned long start,
  52                            unsigned long page_size)
  53{
  54}
  55#endif
  56#endif /* CONFIG_SPARSEMEM_VMEMMAP */
  57
  58static __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 */
  73int 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}
 123