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/io.h>
  31 #include <asm/setup.h>
  32 #include <asm/sections.h>
  33
  34 #include <mm/mmu_decl.h>
  35
  36 unsigned long ioremap_bot;
  37 EXPORT_SYMBOL(ioremap_bot);     /* aka VMALLOC_END */
  38
  39 extern char etext[], _stext[], _sinittext[], _einittext[];
  40
  41 void __iomem *
  42 ioremap(phys_addr_t addr, unsigned long size)
  43 {
  44         pgprot_t prot = pgprot_noncached(PAGE_KERNEL);
  45
  46         return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
  47 }
  48 EXPORT_SYMBOL(ioremap);
  49
  50 void __iomem *
  51 ioremap_wc(phys_addr_t addr, unsigned long size)
  52 {
  53         pgprot_t prot = pgprot_noncached_wc(PAGE_KERNEL);
  54
  55         return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
  56 }
  57 EXPORT_SYMBOL(ioremap_wc);
  58
  59 void __iomem *
  60 ioremap_wt(phys_addr_t addr, unsigned long size)
  61 {
  62         pgprot_t prot = pgprot_cached_wthru(PAGE_KERNEL);
  63
  64         return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
  65 }
  66 EXPORT_SYMBOL(ioremap_wt);
  67
  68 void __iomem *
  69 ioremap_coherent(phys_addr_t addr, unsigned long size)
  70 {
  71         pgprot_t prot = pgprot_cached(PAGE_KERNEL);
  72
  73         return __ioremap_caller(addr, size, prot, __builtin_return_address(0));
  74 }
  75 EXPORT_SYMBOL(ioremap_coherent);
  76
  77 void __iomem *
  78 ioremap_prot(phys_addr_t addr, unsigned long size, unsigned long flags)
  79 {
  80         pte_t pte = __pte(flags);
  81
  82         /* writeable implies dirty for kernel addresses */
  83         if (pte_write(pte))
  84                 pte = pte_mkdirty(pte);
  85
  86         /* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
  87         pte = pte_exprotect(pte);
  88         pte = pte_mkprivileged(pte);
  89
  90         return __ioremap_caller(addr, size, pte_pgprot(pte), __builtin_return_address(0));
  91 }
  92 EXPORT_SYMBOL(ioremap_prot);
  93
  94 void __iomem *
  95 __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
  96 {
  97         return __ioremap_caller(addr, size, __pgprot(flags), __builtin_return_address(0));
  98 }
  99
 100 void __iomem *
 101 __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *caller)
 102 {
 103         unsigned long v, i;
 104         phys_addr_t p;
 105         int err;
 106
 107         /*
 108          * Choose an address to map it to.
 109          * Once the vmalloc system is running, we use it.
 110          * Before then, we use space going down from IOREMAP_TOP
 111          * (ioremap_bot records where we're up to).
 112          */
 113         p = addr & PAGE_MASK;
 114         size = PAGE_ALIGN(addr + size) - p;
 115
 116         /*
 117          * If the address lies within the first 16 MB, assume it's in ISA
 118          * memory space
 119          */
 120         if (p < 16*1024*1024)
 121                 p += _ISA_MEM_BASE;
 122
 123 #ifndef CONFIG_CRASH_DUMP
 124         /*
 125          * Don't allow anybody to remap normal RAM that we're using.
 126          * mem_init() sets high_memory so only do the check after that.
 127          */
 128         if (slab_is_available() && p <= virt_to_phys(high_memory - 1) &&
 129             page_is_ram(__phys_to_pfn(p))) {
 130                 printk("__ioremap(): phys addr 0x%llx is RAM lr %ps\n",
 131                        (unsigned long long)p, __builtin_return_address(0));
 132                 return NULL;
 133         }
 134 #endif
 135
 136         if (size == 0)
 137                 return NULL;
 138
 139         /*
 140          * Is it already mapped?  Perhaps overlapped by a previous
 141          * mapping.
 142          */
 143         v = p_block_mapped(p);
 144         if (v)
 145                 goto out;
 146
 147         if (slab_is_available()) {
 148                 struct vm_struct *area;
 149                 area = get_vm_area_caller(size, VM_IOREMAP, caller);
 150                 if (area == 0)
 151                         return NULL;
 152                 area->phys_addr = p;
 153                 v = (unsigned long) area->addr;
 154         } else {
 155                 v = (ioremap_bot -= size);
 156         }
 157
 158         /*
 159          * Should check if it is a candidate for a BAT mapping
 160          */
 161
 162         err = 0;
 163         for (i = 0; i < size && err == 0; i += PAGE_SIZE)
 164                 err = map_kernel_page(v + i, p + i, prot);
 165         if (err) {
 166                 if (slab_is_available())
 167                         vunmap((void *)v);
 168                 return NULL;
 169         }
 170
 171 out:
 172         return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
 173 }
 174 EXPORT_SYMBOL(__ioremap);
 175
 176 void iounmap(volatile void __iomem *addr)
 177 {
 178         /*
 179          * If mapped by BATs then there is nothing to do.
 180          * Calling vfree() generates a benign warning.
 181          */
 182         if (v_block_mapped((unsigned long)addr))
 183                 return;
 184
 185         if (addr > high_memory && (unsigned long) addr < ioremap_bot)
 186                 vunmap((void *) (PAGE_MASK & (unsigned long)addr));
 187 }
 188 EXPORT_SYMBOL(iounmap);
 189
 190 static void __init *early_alloc_pgtable(unsigned long size)
 191 {
 192         void *ptr = memblock_alloc(size, size);
 193
 194         if (!ptr)
 195                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
 196                       __func__, size, size);
 197
 198         return ptr;
 199 }
 200
 201 static pte_t __init *early_pte_alloc_kernel(pmd_t *pmdp, unsigned long va)
 202 {
 203         if (pmd_none(*pmdp)) {
 204                 pte_t *ptep = early_alloc_pgtable(PTE_FRAG_SIZE);
 205
 206                 pmd_populate_kernel(&init_mm, pmdp, ptep);
 207         }
 208         return pte_offset_kernel(pmdp, va);
 209 }
 210
 211
 212 int __ref map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot)
 213 {
 214         pmd_t *pd;
 215         pte_t *pg;
 216         int err = -ENOMEM;
 217
 218         /* Use upper 10 bits of VA to index the first level map */
 219         pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
 220         /* Use middle 10 bits of VA to index the second-level map */
 221         if (likely(slab_is_available()))
 222                 pg = pte_alloc_kernel(pd, va);
 223         else
 224                 pg = early_pte_alloc_kernel(pd, va);
 225         if (pg != 0) {
 226                 err = 0;
 227                 /* The PTE should never be already set nor present in the
 228                  * hash table
 229                  */
 230                 BUG_ON((pte_present(*pg) | pte_hashpte(*pg)) && pgprot_val(prot));
 231                 set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT, prot));
 232         }
 233         smp_wmb();
 234         return err;
 235 }
 236
 237 /*
 238  * Map in a chunk of physical memory starting at start.
 239  */
 240 static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
 241 {
 242         unsigned long v, s;
 243         phys_addr_t p;
 244         int ktext;
 245
 246         s = offset;
 247         v = PAGE_OFFSET + s;
 248         p = memstart_addr + s;
 249         for (; s < top; s += PAGE_SIZE) {
 250                 ktext = ((char *)v >= _stext && (char *)v < etext) ||
 251                         ((char *)v >= _sinittext && (char *)v < _einittext);
 252                 map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
 253 #ifdef CONFIG_PPC_BOOK3S_32
 254                 if (ktext)
 255                         hash_preload(&init_mm, v, false, 0x300);
 256 #endif
 257                 v += PAGE_SIZE;
 258                 p += PAGE_SIZE;
 259         }
 260 }
 261
 262 void __init mapin_ram(void)
 263 {
 264         struct memblock_region *reg;
 265
 266         for_each_memblock(memory, reg) {
 267                 phys_addr_t base = reg->base;
 268                 phys_addr_t top = min(base + reg->size, total_lowmem);
 269
 270                 if (base >= top)
 271                         continue;
 272                 base = mmu_mapin_ram(base, top);
 273                 if (IS_ENABLED(CONFIG_BDI_SWITCH))
 274                         __mapin_ram_chunk(reg->base, top);
 275                 else
 276                         __mapin_ram_chunk(base, top);
 277         }
 278 }
 279
 280 /* Scan the real Linux page tables and return a PTE pointer for
 281  * a virtual address in a context.
 282  * Returns true (1) if PTE was found, zero otherwise.  The pointer to
 283  * the PTE pointer is unmodified if PTE is not found.
 284  */
 285 static int
 286 get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
 287 {
 288         pgd_t   *pgd;
 289         pud_t   *pud;
 290         pmd_t   *pmd;
 291         pte_t   *pte;
 292         int     retval = 0;
 293
 294         pgd = pgd_offset(mm, addr & PAGE_MASK);
 295         if (pgd) {
 296                 pud = pud_offset(pgd, addr & PAGE_MASK);
 297                 if (pud && pud_present(*pud)) {
 298                         pmd = pmd_offset(pud, addr & PAGE_MASK);
 299                         if (pmd_present(*pmd)) {
 300                                 pte = pte_offset_map(pmd, addr & PAGE_MASK);
 301                                 if (pte) {
 302                                         retval = 1;
 303                                         *ptep = pte;
 304                                         if (pmdp)
 305                                                 *pmdp = pmd;
 306                                         /* XXX caller needs to do pte_unmap, yuck */
 307                                 }
 308                         }
 309                 }
 310         }
 311         return(retval);
 312 }
 313
 314 static int __change_page_attr_noflush(struct page *page, pgprot_t prot)
 315 {
 316         pte_t *kpte;
 317         pmd_t *kpmd;
 318         unsigned long address;
 319
 320         BUG_ON(PageHighMem(page));
 321         address = (unsigned long)page_address(page);
 322
 323         if (v_block_mapped(address))
 324                 return 0;
 325         if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
 326                 return -EINVAL;
 327         __set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
 328         pte_unmap(kpte);
 329
 330         return 0;
 331 }
 332
 333 /*
 334  * Change the page attributes of an page in the linear mapping.
 335  *
 336  * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
 337  */
 338 static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 339 {
 340         int i, err = 0;
 341         unsigned long flags;
 342         struct page *start = page;
 343
 344         local_irq_save(flags);
 345         for (i = 0; i < numpages; i++, page++) {
 346                 err = __change_page_attr_noflush(page, prot);
 347                 if (err)
 348                         break;
 349         }
 350         wmb();
 351         local_irq_restore(flags);
 352         flush_tlb_kernel_range((unsigned long)page_address(start),
 353                                (unsigned long)page_address(page));
 354         return err;
 355 }
 356
 357 void mark_initmem_nx(void)
 358 {
 359         struct page *page = virt_to_page(_sinittext);
 360         unsigned long numpages = PFN_UP((unsigned long)_einittext) -
 361                                  PFN_DOWN((unsigned long)_sinittext);
 362
 363         if (v_block_mapped((unsigned long)_stext) + 1)
 364                 mmu_mark_initmem_nx();
 365         else
 366                 change_page_attr(page, numpages, PAGE_KERNEL);
 367 }
 368
 369 #ifdef CONFIG_STRICT_KERNEL_RWX
 370 void mark_rodata_ro(void)
 371 {
 372         struct page *page;
 373         unsigned long numpages;
 374
 375         if (v_block_mapped((unsigned long)_sinittext)) {
 376                 mmu_mark_rodata_ro();
 377                 return;
 378         }
 379
 380         page = virt_to_page(_stext);
 381         numpages = PFN_UP((unsigned long)_etext) -
 382                    PFN_DOWN((unsigned long)_stext);
 383
 384         change_page_attr(page, numpages, PAGE_KERNEL_ROX);
 385         /*
 386          * mark .rodata as read only. Use __init_begin rather than __end_rodata
 387          * to cover NOTES and EXCEPTION_TABLE.
 388          */
 389         page = virt_to_page(__start_rodata);
 390         numpages = PFN_UP((unsigned long)__init_begin) -
 391                    PFN_DOWN((unsigned long)__start_rodata);
 392
 393         change_page_attr(page, numpages, PAGE_KERNEL_RO);
 394
 395         // mark_initmem_nx() should have already run by now
 396         ptdump_check_wx();
 397 }
 398 #endif
 399
 400 #ifdef CONFIG_DEBUG_PAGEALLOC
 401 void __kernel_map_pages(struct page *page, int numpages, int enable)
 402 {
 403         if (PageHighMem(page))
 404                 return;
 405
 406         change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 407 }
 408 #endif /* CONFIG_DEBUG_PAGEALLOC */