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/pgalloc.h>
  28 #include <asm/fixmap.h>
  29 #include <asm/setup.h>
  30 #include <asm/sections.h>
  31 #include <asm/early_ioremap.h>
  32
  33 #include <mm/mmu_decl.h>
  34
  35 extern char etext[], _stext[], _sinittext[], _einittext[];
  36
  37 static u8 early_fixmap_pagetable[FIXMAP_PTE_SIZE] __page_aligned_data;
  38
  39 notrace void __init early_ioremap_init(void)
  40 {
  41         unsigned long addr = ALIGN_DOWN(FIXADDR_START, PGDIR_SIZE);
  42         pte_t *ptep = (pte_t *)early_fixmap_pagetable;
  43         pmd_t *pmdp = pmd_off_k(addr);
  44
  45         for (; (s32)(FIXADDR_TOP - addr) > 0;
  46              addr += PGDIR_SIZE, ptep += PTRS_PER_PTE, pmdp++)
  47                 pmd_populate_kernel(&init_mm, pmdp, ptep);
  48
  49         early_ioremap_setup();
  50 }
  51
  52 static void __init *early_alloc_pgtable(unsigned long size)
  53 {
  54         void *ptr = memblock_alloc(size, size);
  55
  56         if (!ptr)
  57                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  58                       __func__, size, size);
  59
  60         return ptr;
  61 }
  62
  63 pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
  64 {
  65         if (pmd_none(*pmdp)) {
  66                 pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
  67
  68                 pmd_populate_kernel(&init_mm, pmdp, ptep);
  69         }
  70         return pte_offset_kernel(pmdp, va);
  71 }
  72
  73
  74 int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
  75 {
  76         pmd_t *pd;
  77         pte_t *pg;
  78         int err = -ENOMEM;
  79
  80         /* Use upper 10 bits of VA to index the first level map */
  81         pd = pmd_off_k(va);
  82         /* Use middle 10 bits of VA to index the second-level map */
  83         if (likely(slab_is_available()))
  84                 pg = pte_alloc_kernel(pd, va);
  85         else
  86                 pg = early_pte_alloc_kernel(pd, va);
  87         if (pg) {
  88                 err = 0;
  89                 /* The PTE should never be already set nor present in the
  90                  * hash table
  91                  */
  92                 BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
  93                 set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
  94         }
  95         smp_wmb();
  96         return err;
  97 }
  98
  99 /*
 100  * Map in a chunk of physical memory starting at start.
 101  */
 102 static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
 103 {
 104         unsigned long v, s;
 105         phys_addr_t p;
 106         int ktext;
 107
 108         s = offset;
 109         v = PAGE_OFFSET + s;
 110         p = memstart_addr + s;
 111         for (; s < top; s += PAGE_SIZE) {
 112                 ktext = ((char *)v >= _stext && (char *)v < etext) ||
 113                         ((char *)v >= _sinittext && (char *)v < _einittext);
 114                 map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
 115                 v += PAGE_SIZE;
 116                 p += PAGE_SIZE;
 117         }
 118 }
 119
 120 void __init mapin_ram(void)
 121 {
 122         phys_addr_t base, end;
 123         u64 i;
 124
 125         for_each_mem_range(i, &base, &end) {
 126                 phys_addr_t top = min(end, total_lowmem);
 127
 128                 if (base >= top)
 129                         continue;
 130                 base = mmu_mapin_ram(base, top);
 131                 __mapin_ram_chunk(base, top);
 132         }
 133 }
 134
 135 static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
 136 {
 137         pte_t *kpte;
 138         unsigned long address;
 139
 140         BUG_ON(PageHighMem(page));
 141         address = (unsigned long)page_address(page);
 142
 143         if (v_block_mapped(address))
 144                 return 0;
 145         kpte = virt_to_kpte(address);
 146         if (!kpte)
 147                 return -EINVAL;
 148         __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
 149
 150         return 0;
 151 }
 152
 153 /*
 154  * Change the page attributes of an page in the linear mapping.
 155  *
 156  * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
 157  */
 158 static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 159 {
 160         int i, err = 0;
 161         unsigned long flags;
 162         struct page *start = page;
 163
 164         local_irq_save(flags);
 165         for (i = 0; i < numpages; i++, page++) {
 166                 err = __change_page_attr_noflush(page, prot);
 167                 if (err)
 168                         break;
 169         }
 170         wmb();
 171         local_irq_restore(flags);
 172         flush_tlb_kernel_range((unsigned long)page_address(start),
 173                                (unsigned long)page_address(page));
 174         return err;
 175 }
 176
 177 void mark_initmem_nx(void)
 178 {
 179         struct page *page = virt_to_page(_sinittext);
 180         unsigned long numpages = PFN_UP((unsigned long)_einittext) -
 181                                  PFN_DOWN((unsigned long)_sinittext);
 182
 183         if (v_block_mapped((unsigned long)_sinittext))
 184                 mmu_mark_initmem_nx();
 185         else
 186                 change_page_attr(page, numpages, PAGE_KERNEL);
 187 }
 188
 189 #ifdef CONFIG_STRICT_KERNEL_RWX
 190 void mark_rodata_ro(void)
 191 {
 192         struct page *page;
 193         unsigned long numpages;
 194
 195         if (v_block_mapped((unsigned long)_stext + 1)) {
 196                 mmu_mark_rodata_ro();
 197                 ptdump_check_wx();
 198                 return;
 199         }
 200
 201         page = virt_to_page(_stext);
 202         numpages = PFN_UP((unsigned long)_etext) -
 203                    PFN_DOWN((unsigned long)_stext);
 204
 205         change_page_attr(page, numpages, PAGE_KERNEL_ROX);
 206         /*
 207          * mark .rodata as read only. Use __init_begin rather than __end_rodata
 208          * to cover NOTES and EXCEPTION_TABLE.
 209          */
 210         page = virt_to_page(__start_rodata);
 211         numpages = PFN_UP((unsigned long)__init_begin) -
 212                    PFN_DOWN((unsigned long)__start_rodata);
 213
 214         change_page_attr(page, numpages, PAGE_KERNEL_RO);
 215
 216         // mark_initmem_nx() should have already run by now
 217         ptdump_check_wx();
 218 }
 219 #endif
 220
 221 #ifdef CONFIG_DEBUG_PAGEALLOC
 222 void __kernel_map_pages(struct page *page, int numpages, int enable)
 223 {
 224         if (PageHighMem(page))
 225                 return;
 226
 227         change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 228 }
 229 #endif /* CONFIG_DEBUG_PAGEALLOC */