linux/arch/powerpc/mm/pgtable_32.c
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   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
  35extern char etext[], _stext[], _sinittext[], _einittext[];
  36
  37static 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
  48static 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
  59int __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 */
  87static 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
 109void __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                if (IS_ENABLED(CONFIG_BDI_SWITCH))
 121                        __mapin_ram_chunk(reg->base, top);
 122                else
 123                        __mapin_ram_chunk(base, top);
 124        }
 125}
 126
 127/* Scan the real Linux page tables and return a PTE pointer for
 128 * a virtual address in a context.
 129 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 130 * the PTE pointer is unmodified if PTE is not found.
 131 */
 132static int
 133get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
 134{
 135        pgd_t   *pgd;
 136        pud_t   *pud;
 137        pmd_t   *pmd;
 138        pte_t   *pte;
 139        int     retval = 0;
 140
 141        pgd = pgd_offset(mm, addr & PAGE_MASK);
 142        if (pgd) {
 143                pud = pud_offset(pgd, addr & PAGE_MASK);
 144                if (pud && pud_present(*pud)) {
 145                        pmd = pmd_offset(pud, addr & PAGE_MASK);
 146                        if (pmd_present(*pmd)) {
 147                                pte = pte_offset_map(pmd, addr & PAGE_MASK);
 148                                if (pte) {
 149                                        retval = 1;
 150                                        *ptep = pte;
 151                                        if (pmdp)
 152                                                *pmdp = pmd;
 153                                        /* XXX caller needs to do pte_unmap, yuck */
 154                                }
 155                        }
 156                }
 157        }
 158        return(retval);
 159}
 160
 161static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
 162{
 163        pte_t *kpte;
 164        pmd_t *kpmd;
 165        unsigned long address;
 166
 167        BUG_ON(PageHighMem(page));
 168        address = (unsigned long)page_address(page);
 169
 170        if (v_block_mapped(address))
 171                return 0;
 172        if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
 173                return -EINVAL;
 174        __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
 175        pte_unmap(kpte);
 176
 177        return 0;
 178}
 179
 180/*
 181 * Change the page attributes of an page in the linear mapping.
 182 *
 183 * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
 184 */
 185static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 186{
 187        int i, err = 0;
 188        unsigned long flags;
 189        struct page *start = page;
 190
 191        local_irq_save(flags);
 192        for (i = 0; i < numpages; i++, page++) {
 193                err = __change_page_attr_noflush(page, prot);
 194                if (err)
 195                        break;
 196        }
 197        wmb();
 198        local_irq_restore(flags);
 199        flush_tlb_kernel_range((unsigned long)page_address(start),
 200                               (unsigned long)page_address(page));
 201        return err;
 202}
 203
 204void mark_initmem_nx(void)
 205{
 206        struct page *page = virt_to_page(_sinittext);
 207        unsigned long numpages = PFN_UP((unsigned long)_einittext) -
 208                                 PFN_DOWN((unsigned long)_sinittext);
 209
 210        if (v_block_mapped((unsigned long)_stext + 1))
 211                mmu_mark_initmem_nx();
 212        else
 213                change_page_attr(page, numpages, PAGE_KERNEL);
 214}
 215
 216#ifdef CONFIG_STRICT_KERNEL_RWX
 217void mark_rodata_ro(void)
 218{
 219        struct page *page;
 220        unsigned long numpages;
 221
 222        if (v_block_mapped((unsigned long)_sinittext)) {
 223                mmu_mark_rodata_ro();
 224                return;
 225        }
 226
 227        page = virt_to_page(_stext);
 228        numpages = PFN_UP((unsigned long)_etext) -
 229                   PFN_DOWN((unsigned long)_stext);
 230
 231        change_page_attr(page, numpages, PAGE_KERNEL_ROX);
 232        /*
 233         * mark .rodata as read only. Use __init_begin rather than __end_rodata
 234         * to cover NOTES and EXCEPTION_TABLE.
 235         */
 236        page = virt_to_page(__start_rodata);
 237        numpages = PFN_UP((unsigned long)__init_begin) -
 238                   PFN_DOWN((unsigned long)__start_rodata);
 239
 240        change_page_attr(page, numpages, PAGE_KERNEL_RO);
 241
 242        // mark_initmem_nx() should have already run by now
 243        ptdump_check_wx();
 244}
 245#endif
 246
 247#ifdef CONFIG_DEBUG_PAGEALLOC
 248void __kernel_map_pages(struct page *page, int numpages, int enable)
 249{
 250        if (PageHighMem(page))
 251                return;
 252
 253        change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 254}
 255#endif /* CONFIG_DEBUG_PAGEALLOC */
 256