linux/arch/powerpc/include/asm/book3s/32/pgtable.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_POWERPC_BOOK3S_32_PGTABLE_H
   3#define _ASM_POWERPC_BOOK3S_32_PGTABLE_H
   4
   5#include <asm-generic/pgtable-nopmd.h>
   6
   7/*
   8 * The "classic" 32-bit implementation of the PowerPC MMU uses a hash
   9 * table containing PTEs, together with a set of 16 segment registers,
  10 * to define the virtual to physical address mapping.
  11 *
  12 * We use the hash table as an extended TLB, i.e. a cache of currently
  13 * active mappings.  We maintain a two-level page table tree, much
  14 * like that used by the i386, for the sake of the Linux memory
  15 * management code.  Low-level assembler code in hash_low_32.S
  16 * (procedure hash_page) is responsible for extracting ptes from the
  17 * tree and putting them into the hash table when necessary, and
  18 * updating the accessed and modified bits in the page table tree.
  19 */
  20
  21#define _PAGE_PRESENT   0x001   /* software: pte contains a translation */
  22#define _PAGE_HASHPTE   0x002   /* hash_page has made an HPTE for this pte */
  23#define _PAGE_USER      0x004   /* usermode access allowed */
  24#define _PAGE_GUARDED   0x008   /* G: prohibit speculative access */
  25#define _PAGE_COHERENT  0x010   /* M: enforce memory coherence (SMP systems) */
  26#define _PAGE_NO_CACHE  0x020   /* I: cache inhibit */
  27#define _PAGE_WRITETHRU 0x040   /* W: cache write-through */
  28#define _PAGE_DIRTY     0x080   /* C: page changed */
  29#define _PAGE_ACCESSED  0x100   /* R: page referenced */
  30#define _PAGE_EXEC      0x200   /* software: exec allowed */
  31#define _PAGE_RW        0x400   /* software: user write access allowed */
  32#define _PAGE_SPECIAL   0x800   /* software: Special page */
  33
  34#ifdef CONFIG_PTE_64BIT
  35/* We never clear the high word of the pte */
  36#define _PTE_NONE_MASK  (0xffffffff00000000ULL | _PAGE_HASHPTE)
  37#else
  38#define _PTE_NONE_MASK  _PAGE_HASHPTE
  39#endif
  40
  41#define _PMD_PRESENT    0
  42#define _PMD_PRESENT_MASK (PAGE_MASK)
  43#define _PMD_BAD        (~PAGE_MASK)
  44
  45/* And here we include common definitions */
  46
  47#define _PAGE_KERNEL_RO         0
  48#define _PAGE_KERNEL_ROX        (_PAGE_EXEC)
  49#define _PAGE_KERNEL_RW         (_PAGE_DIRTY | _PAGE_RW)
  50#define _PAGE_KERNEL_RWX        (_PAGE_DIRTY | _PAGE_RW | _PAGE_EXEC)
  51
  52#define _PAGE_HPTEFLAGS _PAGE_HASHPTE
  53
  54#ifndef __ASSEMBLY__
  55
  56static inline bool pte_user(pte_t pte)
  57{
  58        return pte_val(pte) & _PAGE_USER;
  59}
  60#endif /* __ASSEMBLY__ */
  61
  62/*
  63 * Location of the PFN in the PTE. Most 32-bit platforms use the same
  64 * as _PAGE_SHIFT here (ie, naturally aligned).
  65 * Platform who don't just pre-define the value so we don't override it here.
  66 */
  67#define PTE_RPN_SHIFT   (PAGE_SHIFT)
  68
  69/*
  70 * The mask covered by the RPN must be a ULL on 32-bit platforms with
  71 * 64-bit PTEs.
  72 */
  73#ifdef CONFIG_PTE_64BIT
  74#define PTE_RPN_MASK    (~((1ULL << PTE_RPN_SHIFT) - 1))
  75#define MAX_POSSIBLE_PHYSMEM_BITS 36
  76#else
  77#define PTE_RPN_MASK    (~((1UL << PTE_RPN_SHIFT) - 1))
  78#define MAX_POSSIBLE_PHYSMEM_BITS 32
  79#endif
  80
  81/*
  82 * _PAGE_CHG_MASK masks of bits that are to be preserved across
  83 * pgprot changes.
  84 */
  85#define _PAGE_CHG_MASK  (PTE_RPN_MASK | _PAGE_HASHPTE | _PAGE_DIRTY | \
  86                         _PAGE_ACCESSED | _PAGE_SPECIAL)
  87
  88/*
  89 * We define 2 sets of base prot bits, one for basic pages (ie,
  90 * cacheable kernel and user pages) and one for non cacheable
  91 * pages. We always set _PAGE_COHERENT when SMP is enabled or
  92 * the processor might need it for DMA coherency.
  93 */
  94#define _PAGE_BASE_NC   (_PAGE_PRESENT | _PAGE_ACCESSED)
  95#define _PAGE_BASE      (_PAGE_BASE_NC | _PAGE_COHERENT)
  96
  97/*
  98 * Permission masks used to generate the __P and __S table.
  99 *
 100 * Note:__pgprot is defined in arch/powerpc/include/asm/page.h
 101 *
 102 * Write permissions imply read permissions for now.
 103 */
 104#define PAGE_NONE       __pgprot(_PAGE_BASE)
 105#define PAGE_SHARED     __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
 106#define PAGE_SHARED_X   __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC)
 107#define PAGE_COPY       __pgprot(_PAGE_BASE | _PAGE_USER)
 108#define PAGE_COPY_X     __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 109#define PAGE_READONLY   __pgprot(_PAGE_BASE | _PAGE_USER)
 110#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 111
 112/* Permission masks used for kernel mappings */
 113#define PAGE_KERNEL     __pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
 114#define PAGE_KERNEL_NC  __pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | _PAGE_NO_CACHE)
 115#define PAGE_KERNEL_NCG __pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
 116                                 _PAGE_NO_CACHE | _PAGE_GUARDED)
 117#define PAGE_KERNEL_X   __pgprot(_PAGE_BASE | _PAGE_KERNEL_RWX)
 118#define PAGE_KERNEL_RO  __pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
 119#define PAGE_KERNEL_ROX __pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)
 120
 121/*
 122 * Protection used for kernel text. We want the debuggers to be able to
 123 * set breakpoints anywhere, so don't write protect the kernel text
 124 * on platforms where such control is possible.
 125 */
 126#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\
 127        defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE)
 128#define PAGE_KERNEL_TEXT        PAGE_KERNEL_X
 129#else
 130#define PAGE_KERNEL_TEXT        PAGE_KERNEL_ROX
 131#endif
 132
 133/* Make modules code happy. We don't set RO yet */
 134#define PAGE_KERNEL_EXEC        PAGE_KERNEL_X
 135
 136/* Advertise special mapping type for AGP */
 137#define PAGE_AGP                (PAGE_KERNEL_NC)
 138#define HAVE_PAGE_AGP
 139
 140#define PTE_INDEX_SIZE  PTE_SHIFT
 141#define PMD_INDEX_SIZE  0
 142#define PUD_INDEX_SIZE  0
 143#define PGD_INDEX_SIZE  (32 - PGDIR_SHIFT)
 144
 145#define PMD_CACHE_INDEX PMD_INDEX_SIZE
 146#define PUD_CACHE_INDEX PUD_INDEX_SIZE
 147
 148#ifndef __ASSEMBLY__
 149#define PTE_TABLE_SIZE  (sizeof(pte_t) << PTE_INDEX_SIZE)
 150#define PMD_TABLE_SIZE  0
 151#define PUD_TABLE_SIZE  0
 152#define PGD_TABLE_SIZE  (sizeof(pgd_t) << PGD_INDEX_SIZE)
 153
 154/* Bits to mask out from a PMD to get to the PTE page */
 155#define PMD_MASKED_BITS         (PTE_TABLE_SIZE - 1)
 156#endif  /* __ASSEMBLY__ */
 157
 158#define PTRS_PER_PTE    (1 << PTE_INDEX_SIZE)
 159#define PTRS_PER_PGD    (1 << PGD_INDEX_SIZE)
 160
 161/*
 162 * The normal case is that PTEs are 32-bits and we have a 1-page
 163 * 1024-entry pgdir pointing to 1-page 1024-entry PTE pages.  -- paulus
 164 *
 165 * For any >32-bit physical address platform, we can use the following
 166 * two level page table layout where the pgdir is 8KB and the MS 13 bits
 167 * are an index to the second level table.  The combined pgdir/pmd first
 168 * level has 2048 entries and the second level has 512 64-bit PTE entries.
 169 * -Matt
 170 */
 171/* PGDIR_SHIFT determines what a top-level page table entry can map */
 172#define PGDIR_SHIFT     (PAGE_SHIFT + PTE_INDEX_SIZE)
 173#define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
 174#define PGDIR_MASK      (~(PGDIR_SIZE-1))
 175
 176#define USER_PTRS_PER_PGD       (TASK_SIZE / PGDIR_SIZE)
 177
 178#ifndef __ASSEMBLY__
 179
 180int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
 181
 182#endif /* !__ASSEMBLY__ */
 183
 184/*
 185 * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
 186 * value (for now) on others, from where we can start layout kernel
 187 * virtual space that goes below PKMAP and FIXMAP
 188 */
 189#include <asm/fixmap.h>
 190
 191/*
 192 * ioremap_bot starts at that address. Early ioremaps move down from there,
 193 * until mem_init() at which point this becomes the top of the vmalloc
 194 * and ioremap space
 195 */
 196#ifdef CONFIG_HIGHMEM
 197#define IOREMAP_TOP     PKMAP_BASE
 198#else
 199#define IOREMAP_TOP     FIXADDR_START
 200#endif
 201
 202/* PPC32 shares vmalloc area with ioremap */
 203#define IOREMAP_START   VMALLOC_START
 204#define IOREMAP_END     VMALLOC_END
 205
 206/*
 207 * Just any arbitrary offset to the start of the vmalloc VM area: the
 208 * current 16MB value just means that there will be a 64MB "hole" after the
 209 * physical memory until the kernel virtual memory starts.  That means that
 210 * any out-of-bounds memory accesses will hopefully be caught.
 211 * The vmalloc() routines leaves a hole of 4kB between each vmalloced
 212 * area for the same reason. ;)
 213 *
 214 * We no longer map larger than phys RAM with the BATs so we don't have
 215 * to worry about the VMALLOC_OFFSET causing problems.  We do have to worry
 216 * about clashes between our early calls to ioremap() that start growing down
 217 * from ioremap_base being run into the VM area allocations (growing upwards
 218 * from VMALLOC_START).  For this reason we have ioremap_bot to check when
 219 * we actually run into our mappings setup in the early boot with the VM
 220 * system.  This really does become a problem for machines with good amounts
 221 * of RAM.  -- Cort
 222 */
 223#define VMALLOC_OFFSET (0x1000000) /* 16M */
 224
 225#define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
 226
 227#ifdef CONFIG_KASAN_VMALLOC
 228#define VMALLOC_END     ALIGN_DOWN(ioremap_bot, PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
 229#else
 230#define VMALLOC_END     ioremap_bot
 231#endif
 232
 233#define MODULES_END     ALIGN_DOWN(PAGE_OFFSET, SZ_256M)
 234#define MODULES_VADDR   (MODULES_END - SZ_256M)
 235
 236#ifndef __ASSEMBLY__
 237#include <linux/sched.h>
 238#include <linux/threads.h>
 239
 240/* Bits to mask out from a PGD to get to the PUD page */
 241#define PGD_MASKED_BITS         0
 242
 243#define pte_ERROR(e) \
 244        pr_err("%s:%d: bad pte %llx.\n", __FILE__, __LINE__, \
 245                (unsigned long long)pte_val(e))
 246#define pgd_ERROR(e) \
 247        pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 248/*
 249 * Bits in a linux-style PTE.  These match the bits in the
 250 * (hardware-defined) PowerPC PTE as closely as possible.
 251 */
 252
 253#define pte_clear(mm, addr, ptep) \
 254        do { pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0); } while (0)
 255
 256#define pmd_none(pmd)           (!pmd_val(pmd))
 257#define pmd_bad(pmd)            (pmd_val(pmd) & _PMD_BAD)
 258#define pmd_present(pmd)        (pmd_val(pmd) & _PMD_PRESENT_MASK)
 259static inline void pmd_clear(pmd_t *pmdp)
 260{
 261        *pmdp = __pmd(0);
 262}
 263
 264
 265/*
 266 * When flushing the tlb entry for a page, we also need to flush the hash
 267 * table entry.  flush_hash_pages is assembler (for speed) in hashtable.S.
 268 */
 269extern int flush_hash_pages(unsigned context, unsigned long va,
 270                            unsigned long pmdval, int count);
 271
 272/* Add an HPTE to the hash table */
 273extern void add_hash_page(unsigned context, unsigned long va,
 274                          unsigned long pmdval);
 275
 276/* Flush an entry from the TLB/hash table */
 277static inline void flush_hash_entry(struct mm_struct *mm, pte_t *ptep, unsigned long addr)
 278{
 279        if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
 280                unsigned long ptephys = __pa(ptep) & PAGE_MASK;
 281
 282                flush_hash_pages(mm->context.id, addr, ptephys, 1);
 283        }
 284}
 285
 286/*
 287 * PTE updates. This function is called whenever an existing
 288 * valid PTE is updated. This does -not- include set_pte_at()
 289 * which nowadays only sets a new PTE.
 290 *
 291 * Depending on the type of MMU, we may need to use atomic updates
 292 * and the PTE may be either 32 or 64 bit wide. In the later case,
 293 * when using atomic updates, only the low part of the PTE is
 294 * accessed atomically.
 295 */
 296static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
 297                                     unsigned long clr, unsigned long set, int huge)
 298{
 299        pte_basic_t old;
 300        unsigned long tmp;
 301
 302        __asm__ __volatile__(
 303#ifndef CONFIG_PTE_64BIT
 304"1:     lwarx   %0, 0, %3\n"
 305"       andc    %1, %0, %4\n"
 306#else
 307"1:     lwarx   %L0, 0, %3\n"
 308"       lwz     %0, -4(%3)\n"
 309"       andc    %1, %L0, %4\n"
 310#endif
 311"       or      %1, %1, %5\n"
 312"       stwcx.  %1, 0, %3\n"
 313"       bne-    1b"
 314        : "=&r" (old), "=&r" (tmp), "=m" (*p)
 315#ifndef CONFIG_PTE_64BIT
 316        : "r" (p),
 317#else
 318        : "b" ((unsigned long)(p) + 4),
 319#endif
 320          "r" (clr), "r" (set), "m" (*p)
 321        : "cc" );
 322
 323        return old;
 324}
 325
 326/*
 327 * 2.6 calls this without flushing the TLB entry; this is wrong
 328 * for our hash-based implementation, we fix that up here.
 329 */
 330#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 331static inline int __ptep_test_and_clear_young(struct mm_struct *mm,
 332                                              unsigned long addr, pte_t *ptep)
 333{
 334        unsigned long old;
 335        old = pte_update(mm, addr, ptep, _PAGE_ACCESSED, 0, 0);
 336        if (old & _PAGE_HASHPTE)
 337                flush_hash_entry(mm, ptep, addr);
 338
 339        return (old & _PAGE_ACCESSED) != 0;
 340}
 341#define ptep_test_and_clear_young(__vma, __addr, __ptep) \
 342        __ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep)
 343
 344#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
 345static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 346                                       pte_t *ptep)
 347{
 348        return __pte(pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0));
 349}
 350
 351#define __HAVE_ARCH_PTEP_SET_WRPROTECT
 352static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
 353                                      pte_t *ptep)
 354{
 355        pte_update(mm, addr, ptep, _PAGE_RW, 0, 0);
 356}
 357
 358static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 359                                           pte_t *ptep, pte_t entry,
 360                                           unsigned long address,
 361                                           int psize)
 362{
 363        unsigned long set = pte_val(entry) &
 364                (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 365
 366        pte_update(vma->vm_mm, address, ptep, 0, set, 0);
 367
 368        flush_tlb_page(vma, address);
 369}
 370
 371#define __HAVE_ARCH_PTE_SAME
 372#define pte_same(A,B)   (((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)
 373
 374#define pmd_page(pmd)           \
 375        pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
 376
 377/*
 378 * Encode and decode a swap entry.
 379 * Note that the bits we use in a PTE for representing a swap entry
 380 * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used).
 381 *   -- paulus
 382 */
 383#define __swp_type(entry)               ((entry).val & 0x1f)
 384#define __swp_offset(entry)             ((entry).val >> 5)
 385#define __swp_entry(type, offset)       ((swp_entry_t) { (type) | ((offset) << 5) })
 386#define __pte_to_swp_entry(pte)         ((swp_entry_t) { pte_val(pte) >> 3 })
 387#define __swp_entry_to_pte(x)           ((pte_t) { (x).val << 3 })
 388
 389/* Generic accessors to PTE bits */
 390static inline int pte_write(pte_t pte)          { return !!(pte_val(pte) & _PAGE_RW);}
 391static inline int pte_read(pte_t pte)           { return 1; }
 392static inline int pte_dirty(pte_t pte)          { return !!(pte_val(pte) & _PAGE_DIRTY); }
 393static inline int pte_young(pte_t pte)          { return !!(pte_val(pte) & _PAGE_ACCESSED); }
 394static inline int pte_special(pte_t pte)        { return !!(pte_val(pte) & _PAGE_SPECIAL); }
 395static inline int pte_none(pte_t pte)           { return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
 396static inline bool pte_exec(pte_t pte)          { return pte_val(pte) & _PAGE_EXEC; }
 397
 398static inline int pte_present(pte_t pte)
 399{
 400        return pte_val(pte) & _PAGE_PRESENT;
 401}
 402
 403static inline bool pte_hw_valid(pte_t pte)
 404{
 405        return pte_val(pte) & _PAGE_PRESENT;
 406}
 407
 408static inline bool pte_hashpte(pte_t pte)
 409{
 410        return !!(pte_val(pte) & _PAGE_HASHPTE);
 411}
 412
 413static inline bool pte_ci(pte_t pte)
 414{
 415        return !!(pte_val(pte) & _PAGE_NO_CACHE);
 416}
 417
 418/*
 419 * We only find page table entry in the last level
 420 * Hence no need for other accessors
 421 */
 422#define pte_access_permitted pte_access_permitted
 423static inline bool pte_access_permitted(pte_t pte, bool write)
 424{
 425        /*
 426         * A read-only access is controlled by _PAGE_USER bit.
 427         * We have _PAGE_READ set for WRITE and EXECUTE
 428         */
 429        if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte))
 430                return false;
 431
 432        if (write && !pte_write(pte))
 433                return false;
 434
 435        return true;
 436}
 437
 438/* Conversion functions: convert a page and protection to a page entry,
 439 * and a page entry and page directory to the page they refer to.
 440 *
 441 * Even if PTEs can be unsigned long long, a PFN is always an unsigned
 442 * long for now.
 443 */
 444static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
 445{
 446        return __pte(((pte_basic_t)(pfn) << PTE_RPN_SHIFT) |
 447                     pgprot_val(pgprot));
 448}
 449
 450static inline unsigned long pte_pfn(pte_t pte)
 451{
 452        return pte_val(pte) >> PTE_RPN_SHIFT;
 453}
 454
 455/* Generic modifiers for PTE bits */
 456static inline pte_t pte_wrprotect(pte_t pte)
 457{
 458        return __pte(pte_val(pte) & ~_PAGE_RW);
 459}
 460
 461static inline pte_t pte_exprotect(pte_t pte)
 462{
 463        return __pte(pte_val(pte) & ~_PAGE_EXEC);
 464}
 465
 466static inline pte_t pte_mkclean(pte_t pte)
 467{
 468        return __pte(pte_val(pte) & ~_PAGE_DIRTY);
 469}
 470
 471static inline pte_t pte_mkold(pte_t pte)
 472{
 473        return __pte(pte_val(pte) & ~_PAGE_ACCESSED);
 474}
 475
 476static inline pte_t pte_mkexec(pte_t pte)
 477{
 478        return __pte(pte_val(pte) | _PAGE_EXEC);
 479}
 480
 481static inline pte_t pte_mkpte(pte_t pte)
 482{
 483        return pte;
 484}
 485
 486static inline pte_t pte_mkwrite(pte_t pte)
 487{
 488        return __pte(pte_val(pte) | _PAGE_RW);
 489}
 490
 491static inline pte_t pte_mkdirty(pte_t pte)
 492{
 493        return __pte(pte_val(pte) | _PAGE_DIRTY);
 494}
 495
 496static inline pte_t pte_mkyoung(pte_t pte)
 497{
 498        return __pte(pte_val(pte) | _PAGE_ACCESSED);
 499}
 500
 501static inline pte_t pte_mkspecial(pte_t pte)
 502{
 503        return __pte(pte_val(pte) | _PAGE_SPECIAL);
 504}
 505
 506static inline pte_t pte_mkhuge(pte_t pte)
 507{
 508        return pte;
 509}
 510
 511static inline pte_t pte_mkprivileged(pte_t pte)
 512{
 513        return __pte(pte_val(pte) & ~_PAGE_USER);
 514}
 515
 516static inline pte_t pte_mkuser(pte_t pte)
 517{
 518        return __pte(pte_val(pte) | _PAGE_USER);
 519}
 520
 521static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 522{
 523        return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
 524}
 525
 526
 527
 528/* This low level function performs the actual PTE insertion
 529 * Setting the PTE depends on the MMU type and other factors. It's
 530 * an horrible mess that I'm not going to try to clean up now but
 531 * I'm keeping it in one place rather than spread around
 532 */
 533static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 534                                pte_t *ptep, pte_t pte, int percpu)
 535{
 536#if defined(CONFIG_SMP) && !defined(CONFIG_PTE_64BIT)
 537        /* First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
 538         * helper pte_update() which does an atomic update. We need to do that
 539         * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
 540         * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
 541         * the hash bits instead (ie, same as the non-SMP case)
 542         */
 543        if (percpu)
 544                *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
 545                              | (pte_val(pte) & ~_PAGE_HASHPTE));
 546        else
 547                pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, pte_val(pte), 0);
 548
 549#elif defined(CONFIG_PTE_64BIT)
 550        /* Second case is 32-bit with 64-bit PTE.  In this case, we
 551         * can just store as long as we do the two halves in the right order
 552         * with a barrier in between. This is possible because we take care,
 553         * in the hash code, to pre-invalidate if the PTE was already hashed,
 554         * which synchronizes us with any concurrent invalidation.
 555         * In the percpu case, we also fallback to the simple update preserving
 556         * the hash bits
 557         */
 558        if (percpu) {
 559                *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
 560                              | (pte_val(pte) & ~_PAGE_HASHPTE));
 561                return;
 562        }
 563        if (pte_val(*ptep) & _PAGE_HASHPTE)
 564                flush_hash_entry(mm, ptep, addr);
 565        __asm__ __volatile__("\
 566                stw%X0 %2,%0\n\
 567                eieio\n\
 568                stw%X1 %L2,%1"
 569        : "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
 570        : "r" (pte) : "memory");
 571
 572#else
 573        /* Third case is 32-bit hash table in UP mode, we need to preserve
 574         * the _PAGE_HASHPTE bit since we may not have invalidated the previous
 575         * translation in the hash yet (done in a subsequent flush_tlb_xxx())
 576         * and see we need to keep track that this PTE needs invalidating
 577         */
 578        *ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
 579                      | (pte_val(pte) & ~_PAGE_HASHPTE));
 580#endif
 581}
 582
 583/*
 584 * Macro to mark a page protection value as "uncacheable".
 585 */
 586
 587#define _PAGE_CACHE_CTL (_PAGE_COHERENT | _PAGE_GUARDED | _PAGE_NO_CACHE | \
 588                         _PAGE_WRITETHRU)
 589
 590#define pgprot_noncached pgprot_noncached
 591static inline pgprot_t pgprot_noncached(pgprot_t prot)
 592{
 593        return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
 594                        _PAGE_NO_CACHE | _PAGE_GUARDED);
 595}
 596
 597#define pgprot_noncached_wc pgprot_noncached_wc
 598static inline pgprot_t pgprot_noncached_wc(pgprot_t prot)
 599{
 600        return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
 601                        _PAGE_NO_CACHE);
 602}
 603
 604#define pgprot_cached pgprot_cached
 605static inline pgprot_t pgprot_cached(pgprot_t prot)
 606{
 607        return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
 608                        _PAGE_COHERENT);
 609}
 610
 611#define pgprot_cached_wthru pgprot_cached_wthru
 612static inline pgprot_t pgprot_cached_wthru(pgprot_t prot)
 613{
 614        return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
 615                        _PAGE_COHERENT | _PAGE_WRITETHRU);
 616}
 617
 618#define pgprot_cached_noncoherent pgprot_cached_noncoherent
 619static inline pgprot_t pgprot_cached_noncoherent(pgprot_t prot)
 620{
 621        return __pgprot(pgprot_val(prot) & ~_PAGE_CACHE_CTL);
 622}
 623
 624#define pgprot_writecombine pgprot_writecombine
 625static inline pgprot_t pgprot_writecombine(pgprot_t prot)
 626{
 627        return pgprot_noncached_wc(prot);
 628}
 629
 630#endif /* !__ASSEMBLY__ */
 631
 632#endif /*  _ASM_POWERPC_BOOK3S_32_PGTABLE_H */
 633