arch/powerpc/mm/pgtable_32.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * This file contains the routines setting up the linux page tables.
   4  *  -- paulus
   5  *
   6  *  Derived from arch/ppc/mm/init.c:
   7  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   8  *
   9  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  10  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  11  *    Copyright (C) 1996 Paul Mackerras
  12  *
  13  *  Derived from "arch/i386/mm/init.c"
  14  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/types.h>
  20 #include <linux/mm.h>
  21 #include <linux/vmalloc.h>
  22 #include <linux/init.h>
  23 #include <linux/highmem.h>
  24 #include <linux/memblock.h>
  25 #include <linux/slab.h>
  26
  27 #include <asm/pgtable.h>
  28 #include <asm/pgalloc.h>
  29 #include <asm/fixmap.h>
  30 #include <asm/setup.h>
  31 #include <asm/sections.h>
  32
  33 #include <mm/mmu_decl.h>
  34
  35 extern char etext[], _stext[], _sinittext[], _einittext[];
  36
  37 static void __init *early_alloc_pgtable(unsigned long size)
  38 {
  39         void *ptr = memblock_alloc(size, size);
  40
  41         if (!ptr)
  42                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  43                       __func__, size, size);
  44
  45         return ptr;
  46 }
  47
  48 static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
  49 {
  50         if (pmd_none(*pmdp)) {
  51                 pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
  52
  53                 pmd_populate_kernel(&init_mm, pmdp, ptep);
  54         }
  55         return pte_offset_kernel(pmdp, va);
  56 }
  57
  58
  59 int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
  60 {
  61         pmd_t *pd;
  62         pte_t *pg;
  63         int err = -ENOMEM;
  64
  65         /* Use upper 10 bits of VA to index the first level map */
  66         pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
  67         /* Use middle 10 bits of VA to index the second-level map */
  68         if (likely(slab_is_available()))
  69                 pg = pte_alloc_kernel(pd, va);
  70         else
  71                 pg = early_pte_alloc_kernel(pd, va);
  72         if (pg != 0) {
  73                 err = 0;
  74                 /* The PTE should never be already set nor present in the
  75                  * hash table
  76                  */
  77                 BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
  78                 set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
  79         }
  80         smp_wmb();
  81         return err;
  82 }
  83
  84 /*
  85  * Map in a chunk of physical memory starting at start.
  86  */
  87 static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
  88 {
  89         unsigned long v, s;
  90         phys_addr_t p;
  91         int ktext;
  92
  93         s = offset;
  94         v = PAGE_OFFSET + s;
  95         p = memstart_addr + s;
  96         for (; s < top; s += PAGE_SIZE) {
  97                 ktext = ((char *)v >= _stext && (char *)v < etext) ||
  98                         ((char *)v >= _sinittext && (char *)v < _einittext);
  99                 map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
 100 #ifdef CONFIG_PPC_BOOK3S_32
 101                 if (ktext)
 102                         hash_preload(&init_mm, v);
 103 #endif
 104                 v += PAGE_SIZE;
 105                 p += PAGE_SIZE;
 106         }
 107 }
 108
 109 void __init mapin_ram(void)
 110 {
 111         struct memblock_region *reg;
 112
 113         for_each_memblock(memory, reg) {
 114                 phys_addr_t base = reg->base;
 115                 phys_addr_t top = min(base + reg->size, total_lowmem);
 116
 117                 if (base >= top)
 118                         continue;
 119                 base = mmu_mapin_ram(base, top);
 120                 __mapin_ram_chunk(base, top);
 121         }
 122 }
 123
 124 /* Scan the real Linux page tables and return a PTE pointer for
 125  * a virtual address in a context.
 126  * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 127  * the PTE pointer is unmodified if PTE is not found.
 128  */
 129 static int
 130 get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
 131 {
 132         pgd_t   *pgd;
 133         pud_t   *pud;
 134         pmd_t   *pmd;
 135         pte_t   *pte;
 136         int     retval = 0;
 137
 138         pgd = pgd_offset(mm, addr & PAGE_MASK);
 139         if (pgd) {
 140                 pud = pud_offset(pgd, addr & PAGE_MASK);
 141                 if (pud && pud_present(*pud)) {
 142                         pmd = pmd_offset(pud, addr & PAGE_MASK);
 143                         if (pmd_present(*pmd)) {
 144                                 pte = pte_offset_map(pmd, addr & PAGE_MASK);
 145                                 if (pte) {
 146                                         retval = 1;
 147                                         *ptep = pte;
 148                                         if (pmdp)
 149                                                 *pmdp = pmd;
 150                                         /* XXX caller needs to do pte_unmap, yuck */
 151                                 }
 152                         }
 153                 }
 154         }
 155         return(retval);
 156 }
 157
 158 static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
 159 {
 160         pte_t *kpte;
 161         pmd_t *kpmd;
 162         unsigned long address;
 163
 164         BUG_ON(PageHighMem(page));
 165         address = (unsigned long)page_address(page);
 166
 167         if (v_block_mapped(address))
 168                 return 0;
 169         if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
 170                 return -EINVAL;
 171         __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
 172         pte_unmap(kpte);
 173
 174         return 0;
 175 }
 176
 177 /*
 178  * Change the page attributes of an page in the linear mapping.
 179  *
 180  * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
 181  */
 182 static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 183 {
 184         int i, err = 0;
 185         unsigned long flags;
 186         struct page *start = page;
 187
 188         local_irq_save(flags);
 189         for (i = 0; i < numpages; i++, page++) {
 190                 err = __change_page_attr_noflush(page, prot);
 191                 if (err)
 192                         break;
 193         }
 194         wmb();
 195         local_irq_restore(flags);
 196         flush_tlb_kernel_range((unsigned long)page_address(start),
 197                                (unsigned long)page_address(page));
 198         return err;
 199 }
 200
 201 void mark_initmem_nx(void)
 202 {
 203         struct page *page = virt_to_page(_sinittext);
 204         unsigned long numpages = PFN_UP((unsigned long)_einittext) -
 205                                  PFN_DOWN((unsigned long)_sinittext);
 206
 207         if (v_block_mapped((unsigned long)_stext + 1))
 208                 mmu_mark_initmem_nx();
 209         else
 210                 change_page_attr(page, numpages, PAGE_KERNEL);
 211 }
 212
 213 #ifdef CONFIG_STRICT_KERNEL_RWX
 214 void mark_rodata_ro(void)
 215 {
 216         struct page *page;
 217         unsigned long numpages;
 218
 219         if (v_block_mapped((unsigned long)_sinittext)) {
 220                 mmu_mark_rodata_ro();
 221                 ptdump_check_wx();
 222                 return;
 223         }
 224
 225         page = virt_to_page(_stext);
 226         numpages = PFN_UP((unsigned long)_etext) -
 227                    PFN_DOWN((unsigned long)_stext);
 228
 229         change_page_attr(page, numpages, PAGE_KERNEL_ROX);
 230         /*
 231          * mark .rodata as read only. Use __init_begin rather than __end_rodata
 232          * to cover NOTES and EXCEPTION_TABLE.
 233          */
 234         page = virt_to_page(__start_rodata);
 235         numpages = PFN_UP((unsigned long)__init_begin) -
 236                    PFN_DOWN((unsigned long)__start_rodata);
 237
 238         change_page_attr(page, numpages, PAGE_KERNEL_RO);
 239
 240         // mark_initmem_nx() should have already run by now
 241         ptdump_check_wx();
 242 }
 243 #endif
 244
 245 #ifdef CONFIG_DEBUG_PAGEALLOC
 246 void __kernel_map_pages(struct page *page, int numpages, int enable)
 247 {
 248         if (PageHighMem(page))
 249                 return;
 250
 251         change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 252 }
 253 #endif /* CONFIG_DEBUG_PAGEALLOC */