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