arch/x86/mm/ioremap.c

   1 /*
   2  * Re-map IO memory to kernel address space so that we can access it.
   3  * This is needed for high PCI addresses that aren't mapped in the
   4  * 640k-1MB IO memory area on PC's
   5  *
   6  * (C) Copyright 1995 1996 Linus Torvalds
   7  */
   8
   9 #include <linux/bootmem.h>
  10 #include <linux/init.h>
  11 #include <linux/io.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/vmalloc.h>
  15
  16 #include <asm/cacheflush.h>
  17 #include <asm/e820.h>
  18 #include <asm/fixmap.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/tlbflush.h>
  21 #include <asm/pgalloc.h>
  22
  23 enum ioremap_mode {
  24         IOR_MODE_UNCACHED,
  25         IOR_MODE_CACHED,
  26 };
  27
  28 #ifdef CONFIG_X86_64
  29
  30 unsigned long __phys_addr(unsigned long x)
  31 {
  32         if (x >= __START_KERNEL_map)
  33                 return x - __START_KERNEL_map + phys_base;
  34         return x - PAGE_OFFSET;
  35 }
  36 EXPORT_SYMBOL(__phys_addr);
  37
  38 #endif
  39
  40 int page_is_ram(unsigned long pagenr)
  41 {
  42         unsigned long addr, end;
  43         int i;
  44
  45         for (i = 0; i < e820.nr_map; i++) {
  46                 /*
  47                  * Not usable memory:
  48                  */
  49                 if (e820.map[i].type != E820_RAM)
  50                         continue;
  51                 addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT;
  52                 end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT;
  53
  54                 /*
  55                  * Sanity check: Some BIOSen report areas as RAM that
  56                  * are not. Notably the 640->1Mb area, which is the
  57                  * PCI BIOS area.
  58                  */
  59                 if (addr >= (BIOS_BEGIN >> PAGE_SHIFT) &&
  60                     end < (BIOS_END >> PAGE_SHIFT))
  61                         continue;
  62
  63                 if ((pagenr >= addr) && (pagenr < end))
  64                         return 1;
  65         }
  66         return 0;
  67 }
  68
  69 /*
  70  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  71  * conflicts.
  72  */
  73 static int ioremap_change_attr(unsigned long vaddr, unsigned long size,
  74                                enum ioremap_mode mode)
  75 {
  76         unsigned long nrpages = size >> PAGE_SHIFT;
  77         int err;
  78
  79         switch (mode) {
  80         case IOR_MODE_UNCACHED:
  81         default:
  82                 err = set_memory_uc(vaddr, nrpages);
  83                 break;
  84         case IOR_MODE_CACHED:
  85                 err = set_memory_wb(vaddr, nrpages);
  86                 break;
  87         }
  88
  89         return err;
  90 }
  91
  92 /*
  93  * Remap an arbitrary physical address space into the kernel virtual
  94  * address space. Needed when the kernel wants to access high addresses
  95  * directly.
  96  *
  97  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  98  * have to convert them into an offset in a page-aligned mapping, but the
  99  * caller shouldn't need to know that small detail.
 100  */
 101 static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
 102                                enum ioremap_mode mode)
 103 {
 104         unsigned long pfn, offset, last_addr, vaddr;
 105         struct vm_struct *area;
 106         pgprot_t prot;
 107
 108         /* Don't allow wraparound or zero size */
 109         last_addr = phys_addr + size - 1;
 110         if (!size || last_addr < phys_addr)
 111                 return NULL;
 112
 113         /*
 114          * Don't remap the low PCI/ISA area, it's always mapped..
 115          */
 116         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 117                 return (__force void __iomem *)phys_to_virt(phys_addr);
 118
 119         /*
 120          * Don't allow anybody to remap normal RAM that we're using..
 121          */
 122         for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
 123              (pfn << PAGE_SHIFT) < last_addr; pfn++) {
 124                 if (page_is_ram(pfn) && pfn_valid(pfn) &&
 125                     !PageReserved(pfn_to_page(pfn)))
 126                         return NULL;
 127         }
 128
 129         switch (mode) {
 130         case IOR_MODE_UNCACHED:
 131         default:
 132                 prot = PAGE_KERNEL_NOCACHE;
 133                 break;
 134         case IOR_MODE_CACHED:
 135                 prot = PAGE_KERNEL;
 136                 break;
 137         }
 138
 139         /*
 140          * Mappings have to be page-aligned
 141          */
 142         offset = phys_addr & ~PAGE_MASK;
 143         phys_addr &= PAGE_MASK;
 144         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 145
 146         /*
 147          * Ok, go for it..
 148          */
 149         area = get_vm_area(size, VM_IOREMAP);
 150         if (!area)
 151                 return NULL;
 152         area->phys_addr = phys_addr;
 153         vaddr = (unsigned long) area->addr;
 154         if (ioremap_page_range(vaddr, vaddr + size, phys_addr, prot)) {
 155                 remove_vm_area((void *)(vaddr & PAGE_MASK));
 156                 return NULL;
 157         }
 158
 159         if (ioremap_change_attr(vaddr, size, mode) < 0) {
 160                 vunmap(area->addr);
 161                 return NULL;
 162         }
 163
 164         return (void __iomem *) (vaddr + offset);
 165 }
 166
 167 /**
 168  * ioremap_nocache     -   map bus memory into CPU space
 169  * @offset:    bus address of the memory
 170  * @size:      size of the resource to map
 171  *
 172  * ioremap_nocache performs a platform specific sequence of operations to
 173  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 174  * writew/writel functions and the other mmio helpers. The returned
 175  * address is not guaranteed to be usable directly as a virtual
 176  * address.
 177  *
 178  * This version of ioremap ensures that the memory is marked uncachable
 179  * on the CPU as well as honouring existing caching rules from things like
 180  * the PCI bus. Note that there are other caches and buffers on many
 181  * busses. In particular driver authors should read up on PCI writes
 182  *
 183  * It's useful if some control registers are in such an area and
 184  * write combining or read caching is not desirable:
 185  *
 186  * Must be freed with iounmap.
 187  */
 188 void __iomem *ioremap_nocache(unsigned long phys_addr, unsigned long size)
 189 {
 190         return __ioremap(phys_addr, size, IOR_MODE_UNCACHED);
 191 }
 192 EXPORT_SYMBOL(ioremap_nocache);
 193
 194 void __iomem *ioremap_cache(unsigned long phys_addr, unsigned long size)
 195 {
 196         return __ioremap(phys_addr, size, IOR_MODE_CACHED);
 197 }
 198 EXPORT_SYMBOL(ioremap_cache);
 199
 200 /**
 201  * iounmap - Free a IO remapping
 202  * @addr: virtual address from ioremap_*
 203  *
 204  * Caller must ensure there is only one unmapping for the same pointer.
 205  */
 206 void iounmap(volatile void __iomem *addr)
 207 {
 208         struct vm_struct *p, *o;
 209
 210         if ((void __force *)addr <= high_memory)
 211                 return;
 212
 213         /*
 214          * __ioremap special-cases the PCI/ISA range by not instantiating a
 215          * vm_area and by simply returning an address into the kernel mapping
 216          * of ISA space.   So handle that here.
 217          */
 218         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 219             addr < phys_to_virt(ISA_END_ADDRESS))
 220                 return;
 221
 222         addr = (volatile void __iomem *)
 223                 (PAGE_MASK & (unsigned long __force)addr);
 224
 225         /* Use the vm area unlocked, assuming the caller
 226            ensures there isn't another iounmap for the same address
 227            in parallel. Reuse of the virtual address is prevented by
 228            leaving it in the global lists until we're done with it.
 229            cpa takes care of the direct mappings. */
 230         read_lock(&vmlist_lock);
 231         for (p = vmlist; p; p = p->next) {
 232                 if (p->addr == addr)
 233                         break;
 234         }
 235         read_unlock(&vmlist_lock);
 236
 237         if (!p) {
 238                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 239                 dump_stack();
 240                 return;
 241         }
 242
 243         /* Finally remove it */
 244         o = remove_vm_area((void *)addr);
 245         BUG_ON(p != o || o == NULL);
 246         kfree(p);
 247 }
 248 EXPORT_SYMBOL(iounmap);
 249
 250 #ifdef CONFIG_X86_32
 251
 252 int __initdata early_ioremap_debug;
 253
 254 static int __init early_ioremap_debug_setup(char *str)
 255 {
 256         early_ioremap_debug = 1;
 257
 258         return 0;
 259 }
 260 early_param("early_ioremap_debug", early_ioremap_debug_setup);
 261
 262 static __initdata int after_paging_init;
 263 static __initdata pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)]
 264                                 __attribute__((aligned(PAGE_SIZE)));
 265
 266 static inline pmd_t * __init early_ioremap_pmd(unsigned long addr)
 267 {
 268         /* Don't assume we're using swapper_pg_dir at this point */
 269         pgd_t *base = __va(read_cr3());
 270         pgd_t *pgd = &base[pgd_index(addr)];
 271         pud_t *pud = pud_offset(pgd, addr);
 272         pmd_t *pmd = pmd_offset(pud, addr);
 273
 274         return pmd;
 275 }
 276
 277 static inline pte_t * __init early_ioremap_pte(unsigned long addr)
 278 {
 279         return &bm_pte[pte_index(addr)];
 280 }
 281
 282 void __init early_ioremap_init(void)
 283 {
 284         pmd_t *pmd;
 285
 286         if (early_ioremap_debug)
 287                 printk(KERN_INFO "early_ioremap_init()\n");
 288
 289         pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
 290         memset(bm_pte, 0, sizeof(bm_pte));
 291         pmd_populate_kernel(&init_mm, pmd, bm_pte);
 292
 293         /*
 294          * The boot-ioremap range spans multiple pmds, for which
 295          * we are not prepared:
 296          */
 297         if (pmd != early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END))) {
 298                 WARN_ON(1);
 299                 printk(KERN_WARNING "pmd %p != %p\n",
 300                        pmd, early_ioremap_pmd(fix_to_virt(FIX_BTMAP_END)));
 301                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n",
 302                         fix_to_virt(FIX_BTMAP_BEGIN));
 303                 printk(KERN_WARNING "fix_to_virt(FIX_BTMAP_END):   %08lx\n",
 304                         fix_to_virt(FIX_BTMAP_END));
 305
 306                 printk(KERN_WARNING "FIX_BTMAP_END:       %d\n", FIX_BTMAP_END);
 307                 printk(KERN_WARNING "FIX_BTMAP_BEGIN:     %d\n",
 308                        FIX_BTMAP_BEGIN);
 309         }
 310 }
 311
 312 void __init early_ioremap_clear(void)
 313 {
 314         pmd_t *pmd;
 315
 316         if (early_ioremap_debug)
 317                 printk(KERN_INFO "early_ioremap_clear()\n");
 318
 319         pmd = early_ioremap_pmd(fix_to_virt(FIX_BTMAP_BEGIN));
 320         pmd_clear(pmd);
 321         paravirt_release_pt(__pa(bm_pte) >> PAGE_SHIFT);
 322         __flush_tlb_all();
 323 }
 324
 325 void __init early_ioremap_reset(void)
 326 {
 327         enum fixed_addresses idx;
 328         unsigned long addr, phys;
 329         pte_t *pte;
 330
 331         after_paging_init = 1;
 332         for (idx = FIX_BTMAP_BEGIN; idx >= FIX_BTMAP_END; idx--) {
 333                 addr = fix_to_virt(idx);
 334                 pte = early_ioremap_pte(addr);
 335                 if (pte_present(*pte)) {
 336                         phys = pte_val(*pte) & PAGE_MASK;
 337                         set_fixmap(idx, phys);
 338                 }
 339         }
 340 }
 341
 342 static void __init __early_set_fixmap(enum fixed_addresses idx,
 343                                    unsigned long phys, pgprot_t flags)
 344 {
 345         unsigned long addr = __fix_to_virt(idx);
 346         pte_t *pte;
 347
 348         if (idx >= __end_of_fixed_addresses) {
 349                 BUG();
 350                 return;
 351         }
 352         pte = early_ioremap_pte(addr);
 353         if (pgprot_val(flags))
 354                 set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags));
 355         else
 356                 pte_clear(NULL, addr, pte);
 357         __flush_tlb_one(addr);
 358 }
 359
 360 static inline void __init early_set_fixmap(enum fixed_addresses idx,
 361                                         unsigned long phys)
 362 {
 363         if (after_paging_init)
 364                 set_fixmap(idx, phys);
 365         else
 366                 __early_set_fixmap(idx, phys, PAGE_KERNEL);
 367 }
 368
 369 static inline void __init early_clear_fixmap(enum fixed_addresses idx)
 370 {
 371         if (after_paging_init)
 372                 clear_fixmap(idx);
 373         else
 374                 __early_set_fixmap(idx, 0, __pgprot(0));
 375 }
 376
 377
 378 int __initdata early_ioremap_nested;
 379
 380 static int __init check_early_ioremap_leak(void)
 381 {
 382         if (!early_ioremap_nested)
 383                 return 0;
 384
 385         printk(KERN_WARNING
 386                "Debug warning: early ioremap leak of %d areas detected.\n",
 387                early_ioremap_nested);
 388         printk(KERN_WARNING
 389                "please boot with early_ioremap_debug and report the dmesg.\n");
 390         WARN_ON(1);
 391
 392         return 1;
 393 }
 394 late_initcall(check_early_ioremap_leak);
 395
 396 void __init *early_ioremap(unsigned long phys_addr, unsigned long size)
 397 {
 398         unsigned long offset, last_addr;
 399         unsigned int nrpages, nesting;
 400         enum fixed_addresses idx0, idx;
 401
 402         WARN_ON(system_state != SYSTEM_BOOTING);
 403
 404         nesting = early_ioremap_nested;
 405         if (early_ioremap_debug) {
 406                 printk(KERN_INFO "early_ioremap(%08lx, %08lx) [%d] => ",
 407                        phys_addr, size, nesting);
 408                 dump_stack();
 409         }
 410
 411         /* Don't allow wraparound or zero size */
 412         last_addr = phys_addr + size - 1;
 413         if (!size || last_addr < phys_addr) {
 414                 WARN_ON(1);
 415                 return NULL;
 416         }
 417
 418         if (nesting >= FIX_BTMAPS_NESTING) {
 419                 WARN_ON(1);
 420                 return NULL;
 421         }
 422         early_ioremap_nested++;
 423         /*
 424          * Mappings have to be page-aligned
 425          */
 426         offset = phys_addr & ~PAGE_MASK;
 427         phys_addr &= PAGE_MASK;
 428         size = PAGE_ALIGN(last_addr) - phys_addr;
 429
 430         /*
 431          * Mappings have to fit in the FIX_BTMAP area.
 432          */
 433         nrpages = size >> PAGE_SHIFT;
 434         if (nrpages > NR_FIX_BTMAPS) {
 435                 WARN_ON(1);
 436                 return NULL;
 437         }
 438
 439         /*
 440          * Ok, go for it..
 441          */
 442         idx0 = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 443         idx = idx0;
 444         while (nrpages > 0) {
 445                 early_set_fixmap(idx, phys_addr);
 446                 phys_addr += PAGE_SIZE;
 447                 --idx;
 448                 --nrpages;
 449         }
 450         if (early_ioremap_debug)
 451                 printk(KERN_CONT "%08lx + %08lx\n", offset, fix_to_virt(idx0));
 452
 453         return (void *) (offset + fix_to_virt(idx0));
 454 }
 455
 456 void __init early_iounmap(void *addr, unsigned long size)
 457 {
 458         unsigned long virt_addr;
 459         unsigned long offset;
 460         unsigned int nrpages;
 461         enum fixed_addresses idx;
 462         unsigned int nesting;
 463
 464         nesting = --early_ioremap_nested;
 465         WARN_ON(nesting < 0);
 466
 467         if (early_ioremap_debug) {
 468                 printk(KERN_INFO "early_iounmap(%p, %08lx) [%d]\n", addr,
 469                        size, nesting);
 470                 dump_stack();
 471         }
 472
 473         virt_addr = (unsigned long)addr;
 474         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)) {
 475                 WARN_ON(1);
 476                 return;
 477         }
 478         offset = virt_addr & ~PAGE_MASK;
 479         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 480
 481         idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*nesting;
 482         while (nrpages > 0) {
 483                 early_clear_fixmap(idx);
 484                 --idx;
 485                 --nrpages;
 486         }
 487 }
 488
 489 void __this_fixmap_does_not_exist(void)
 490 {
 491         WARN_ON(1);
 492 }
 493
 494 #endif /* CONFIG_X86_32 */