root/arch/powerpc/mm/nohash/book3e_pgtable.c

DEFINITIONS

1. vmemmap_create_mapping
2. vmemmap_remove_mapping
3. early_alloc_pgtable
4. map_kernel_page

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2005, Paul Mackerras, IBM Corporation.
   4  * Copyright 2009, Benjamin Herrenschmidt, IBM Corporation.
   5  * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
   6  */
   7 
   8 #include <linux/sched.h>
   9 #include <linux/memblock.h>
  10 #include <asm/pgalloc.h>
  11 #include <asm/tlb.h>
  12 #include <asm/dma.h>
  13 
  14 #include <mm/mmu_decl.h>
  15 
  16 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  17 /*
  18  * On Book3E CPUs, the vmemmap is currently mapped in the top half of
  19  * the vmalloc space using normal page tables, though the size of
  20  * pages encoded in the PTEs can be different
  21  */
  22 int __meminit vmemmap_create_mapping(unsigned long start,
  23                                      unsigned long page_size,
  24                                      unsigned long phys)
  25 {
  26         /* Create a PTE encoding without page size */
  27         unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
  28                 _PAGE_KERNEL_RW;
  29 
  30         /* PTEs only contain page size encodings up to 32M */
  31         BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);
  32 
  33         /* Encode the size in the PTE */
  34         flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;
  35 
  36         /* For each PTE for that area, map things. Note that we don't
  37          * increment phys because all PTEs are of the large size and
  38          * thus must have the low bits clear
  39          */
  40         for (i = 0; i < page_size; i += PAGE_SIZE)
  41                 BUG_ON(map_kernel_page(start + i, phys, __pgprot(flags)));
  42 
  43         return 0;
  44 }
  45 
  46 #ifdef CONFIG_MEMORY_HOTPLUG
  47 void vmemmap_remove_mapping(unsigned long start,
  48                             unsigned long page_size)
  49 {
  50 }
  51 #endif
  52 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
  53 
  54 static void __init *early_alloc_pgtable(unsigned long size)
  55 {
  56         void *ptr;
  57 
  58         ptr = memblock_alloc_try_nid(size, size, MEMBLOCK_LOW_LIMIT,
  59                                      __pa(MAX_DMA_ADDRESS), NUMA_NO_NODE);
  60 
  61         if (!ptr)
  62                 panic("%s: Failed to allocate %lu bytes align=0x%lx max_addr=%lx\n",
  63                       __func__, size, size, __pa(MAX_DMA_ADDRESS));
  64 
  65         return ptr;
  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 __ref map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
  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         } else {
  93                 pgdp = pgd_offset_k(ea);
  94 #ifndef __PAGETABLE_PUD_FOLDED
  95                 if (pgd_none(*pgdp)) {
  96                         pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
  97                         pgd_populate(&init_mm, pgdp, pudp);
  98                 }
  99 #endif /* !__PAGETABLE_PUD_FOLDED */
 100                 pudp = pud_offset(pgdp, ea);
 101                 if (pud_none(*pudp)) {
 102                         pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
 103                         pud_populate(&init_mm, pudp, pmdp);
 104                 }
 105                 pmdp = pmd_offset(pudp, ea);
 106                 if (!pmd_present(*pmdp)) {
 107                         ptep = early_alloc_pgtable(PAGE_SIZE);
 108                         pmd_populate_kernel(&init_mm, pmdp, ptep);
 109                 }
 110                 ptep = pte_offset_kernel(pmdp, ea);
 111         }
 112         set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
 113 
 114         smp_wmb();
 115         return 0;
 116 }