arch/powerpc/mm/nohash/book3e_pgtable.c

   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 #include <asm/code-patching.h>
  14
  15 #include <mm/mmu_decl.h>
  16
  17 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  18 /*
  19  * On Book3E CPUs, the vmemmap is currently mapped in the top half of
  20  * the vmalloc space using normal page tables, though the size of
  21  * pages encoded in the PTEs can be different
  22  */
  23 int __meminit vmemmap_create_mapping(unsigned long start,
  24                                      unsigned long page_size,
  25                                      unsigned long phys)
  26 {
  27         /* Create a PTE encoding without page size */
  28         unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
  29                 _PAGE_KERNEL_RW;
  30
  31         /* PTEs only contain page size encodings up to 32M */
  32         BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);
  33
  34         /* Encode the size in the PTE */
  35         flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;
  36
  37         /* For each PTE for that area, map things. Note that we don't
  38          * increment phys because all PTEs are of the large size and
  39          * thus must have the low bits clear
  40          */
  41         for (i = 0; i < page_size; i += PAGE_SIZE)
  42                 BUG_ON(map_kernel_page(start + i, phys, __pgprot(flags)));
  43
  44         return 0;
  45 }
  46
  47 #ifdef CONFIG_MEMORY_HOTPLUG
  48 void vmemmap_remove_mapping(unsigned long start,
  49                             unsigned long page_size)
  50 {
  51 }
  52 #endif
  53 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
  54
  55 static void __init *early_alloc_pgtable(unsigned long size)
  56 {
  57         void *ptr;
  58
  59         ptr = memblock_alloc_try_nid(size, size, MEMBLOCK_LOW_LIMIT,
  60                                      __pa(MAX_DMA_ADDRESS), NUMA_NO_NODE);
  61
  62         if (!ptr)
  63                 panic("%s: Failed to allocate %lu bytes align=0x%lx max_addr=%lx\n",
  64                       __func__, size, size, __pa(MAX_DMA_ADDRESS));
  65
  66         return ptr;
  67 }
  68
  69 /*
  70  * map_kernel_page currently only called by __ioremap
  71  * map_kernel_page adds an entry to the ioremap page table
  72  * and adds an entry to the HPT, possibly bolting it
  73  */
  74 int __ref map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot)
  75 {
  76         pgd_t *pgdp;
  77         p4d_t *p4dp;
  78         pud_t *pudp;
  79         pmd_t *pmdp;
  80         pte_t *ptep;
  81
  82         BUILD_BUG_ON(TASK_SIZE_USER64 > PGTABLE_RANGE);
  83         if (slab_is_available()) {
  84                 pgdp = pgd_offset_k(ea);
  85                 p4dp = p4d_offset(pgdp, ea);
  86                 pudp = pud_alloc(&init_mm, p4dp, ea);
  87                 if (!pudp)
  88                         return -ENOMEM;
  89                 pmdp = pmd_alloc(&init_mm, pudp, ea);
  90                 if (!pmdp)
  91                         return -ENOMEM;
  92                 ptep = pte_alloc_kernel(pmdp, ea);
  93                 if (!ptep)
  94                         return -ENOMEM;
  95         } else {
  96                 pgdp = pgd_offset_k(ea);
  97                 p4dp = p4d_offset(pgdp, ea);
  98                 if (p4d_none(*p4dp)) {
  99                         pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
 100                         p4d_populate(&init_mm, p4dp, pudp);
 101                 }
 102                 pudp = pud_offset(p4dp, ea);
 103                 if (pud_none(*pudp)) {
 104                         pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
 105                         pud_populate(&init_mm, pudp, pmdp);
 106                 }
 107                 pmdp = pmd_offset(pudp, ea);
 108                 if (!pmd_present(*pmdp)) {
 109                         ptep = early_alloc_pgtable(PTE_TABLE_SIZE);
 110                         pmd_populate_kernel(&init_mm, pmdp, ptep);
 111                 }
 112                 ptep = pte_offset_kernel(pmdp, ea);
 113         }
 114         set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot));
 115
 116         smp_wmb();
 117         return 0;
 118 }
 119
 120 void __patch_exception(int exc, unsigned long addr)
 121 {
 122         unsigned int *ibase = &interrupt_base_book3e;
 123
 124         /*
 125          * Our exceptions vectors start with a NOP and -then- a branch
 126          * to deal with single stepping from userspace which stops on
 127          * the second instruction. Thus we need to patch the second
 128          * instruction of the exception, not the first one.
 129          */
 130
 131         patch_branch(ibase + (exc / 4) + 1, addr, 0);
 132 }