xref: /linux/arch/powerpc/include/asm/book3s/32/pgtable.h (revision 2b64b2ed277ff23e785fbdb65098ee7e1252d64f)
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 #define __ARCH_USE_5LEVEL_HACK
6 #include <asm-generic/pgtable-nopmd.h>
7 
8 #include <asm/book3s/32/hash.h>
9 
10 /* And here we include common definitions */
11 
12 #define _PAGE_KERNEL_RO		0
13 #define _PAGE_KERNEL_ROX	(_PAGE_EXEC)
14 #define _PAGE_KERNEL_RW		(_PAGE_DIRTY | _PAGE_RW)
15 #define _PAGE_KERNEL_RWX	(_PAGE_DIRTY | _PAGE_RW | _PAGE_EXEC)
16 
17 #define _PAGE_HPTEFLAGS _PAGE_HASHPTE
18 
19 #ifndef __ASSEMBLY__
20 
21 static inline bool pte_user(pte_t pte)
22 {
23 	return pte_val(pte) & _PAGE_USER;
24 }
25 #endif /* __ASSEMBLY__ */
26 
27 /*
28  * Location of the PFN in the PTE. Most 32-bit platforms use the same
29  * as _PAGE_SHIFT here (ie, naturally aligned).
30  * Platform who don't just pre-define the value so we don't override it here.
31  */
32 #define PTE_RPN_SHIFT	(PAGE_SHIFT)
33 
34 /*
35  * The mask covered by the RPN must be a ULL on 32-bit platforms with
36  * 64-bit PTEs.
37  */
38 #ifdef CONFIG_PTE_64BIT
39 #define PTE_RPN_MASK	(~((1ULL << PTE_RPN_SHIFT) - 1))
40 #else
41 #define PTE_RPN_MASK	(~((1UL << PTE_RPN_SHIFT) - 1))
42 #endif
43 
44 /*
45  * _PAGE_CHG_MASK masks of bits that are to be preserved across
46  * pgprot changes.
47  */
48 #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HASHPTE | _PAGE_DIRTY | \
49 			 _PAGE_ACCESSED | _PAGE_SPECIAL)
50 
51 /*
52  * We define 2 sets of base prot bits, one for basic pages (ie,
53  * cacheable kernel and user pages) and one for non cacheable
54  * pages. We always set _PAGE_COHERENT when SMP is enabled or
55  * the processor might need it for DMA coherency.
56  */
57 #define _PAGE_BASE_NC	(_PAGE_PRESENT | _PAGE_ACCESSED)
58 #define _PAGE_BASE	(_PAGE_BASE_NC | _PAGE_COHERENT)
59 
60 /*
61  * Permission masks used to generate the __P and __S table.
62  *
63  * Note:__pgprot is defined in arch/powerpc/include/asm/page.h
64  *
65  * Write permissions imply read permissions for now.
66  */
67 #define PAGE_NONE	__pgprot(_PAGE_BASE)
68 #define PAGE_SHARED	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
69 #define PAGE_SHARED_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC)
70 #define PAGE_COPY	__pgprot(_PAGE_BASE | _PAGE_USER)
71 #define PAGE_COPY_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
72 #define PAGE_READONLY	__pgprot(_PAGE_BASE | _PAGE_USER)
73 #define PAGE_READONLY_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
74 
75 /* Permission masks used for kernel mappings */
76 #define PAGE_KERNEL	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
77 #define PAGE_KERNEL_NC	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | _PAGE_NO_CACHE)
78 #define PAGE_KERNEL_NCG	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
79 				 _PAGE_NO_CACHE | _PAGE_GUARDED)
80 #define PAGE_KERNEL_X	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RWX)
81 #define PAGE_KERNEL_RO	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
82 #define PAGE_KERNEL_ROX	__pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)
83 
84 /*
85  * Protection used for kernel text. We want the debuggers to be able to
86  * set breakpoints anywhere, so don't write protect the kernel text
87  * on platforms where such control is possible.
88  */
89 #if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\
90 	defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE)
91 #define PAGE_KERNEL_TEXT	PAGE_KERNEL_X
92 #else
93 #define PAGE_KERNEL_TEXT	PAGE_KERNEL_ROX
94 #endif
95 
96 /* Make modules code happy. We don't set RO yet */
97 #define PAGE_KERNEL_EXEC	PAGE_KERNEL_X
98 
99 /* Advertise special mapping type for AGP */
100 #define PAGE_AGP		(PAGE_KERNEL_NC)
101 #define HAVE_PAGE_AGP
102 
103 #define PTE_INDEX_SIZE	PTE_SHIFT
104 #define PMD_INDEX_SIZE	0
105 #define PUD_INDEX_SIZE	0
106 #define PGD_INDEX_SIZE	(32 - PGDIR_SHIFT)
107 
108 #define PMD_CACHE_INDEX	PMD_INDEX_SIZE
109 #define PUD_CACHE_INDEX	PUD_INDEX_SIZE
110 
111 #ifndef __ASSEMBLY__
112 #define PTE_TABLE_SIZE	(sizeof(pte_t) << PTE_INDEX_SIZE)
113 #define PMD_TABLE_SIZE	0
114 #define PUD_TABLE_SIZE	0
115 #define PGD_TABLE_SIZE	(sizeof(pgd_t) << PGD_INDEX_SIZE)
116 #endif	/* __ASSEMBLY__ */
117 
118 #define PTRS_PER_PTE	(1 << PTE_INDEX_SIZE)
119 #define PTRS_PER_PGD	(1 << PGD_INDEX_SIZE)
120 
121 /*
122  * The normal case is that PTEs are 32-bits and we have a 1-page
123  * 1024-entry pgdir pointing to 1-page 1024-entry PTE pages.  -- paulus
124  *
125  * For any >32-bit physical address platform, we can use the following
126  * two level page table layout where the pgdir is 8KB and the MS 13 bits
127  * are an index to the second level table.  The combined pgdir/pmd first
128  * level has 2048 entries and the second level has 512 64-bit PTE entries.
129  * -Matt
130  */
131 /* PGDIR_SHIFT determines what a top-level page table entry can map */
132 #define PGDIR_SHIFT	(PAGE_SHIFT + PTE_INDEX_SIZE)
133 #define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
134 #define PGDIR_MASK	(~(PGDIR_SIZE-1))
135 
136 #define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
137 /*
138  * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
139  * value (for now) on others, from where we can start layout kernel
140  * virtual space that goes below PKMAP and FIXMAP
141  */
142 #ifdef CONFIG_HIGHMEM
143 #define KVIRT_TOP	PKMAP_BASE
144 #else
145 #define KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
146 #endif
147 
148 /*
149  * ioremap_bot starts at that address. Early ioremaps move down from there,
150  * until mem_init() at which point this becomes the top of the vmalloc
151  * and ioremap space
152  */
153 #ifdef CONFIG_NOT_COHERENT_CACHE
154 #define IOREMAP_TOP	((KVIRT_TOP - CONFIG_CONSISTENT_SIZE) & PAGE_MASK)
155 #else
156 #define IOREMAP_TOP	KVIRT_TOP
157 #endif
158 
159 /*
160  * Just any arbitrary offset to the start of the vmalloc VM area: the
161  * current 16MB value just means that there will be a 64MB "hole" after the
162  * physical memory until the kernel virtual memory starts.  That means that
163  * any out-of-bounds memory accesses will hopefully be caught.
164  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
165  * area for the same reason. ;)
166  *
167  * We no longer map larger than phys RAM with the BATs so we don't have
168  * to worry about the VMALLOC_OFFSET causing problems.  We do have to worry
169  * about clashes between our early calls to ioremap() that start growing down
170  * from ioremap_base being run into the VM area allocations (growing upwards
171  * from VMALLOC_START).  For this reason we have ioremap_bot to check when
172  * we actually run into our mappings setup in the early boot with the VM
173  * system.  This really does become a problem for machines with good amounts
174  * of RAM.  -- Cort
175  */
176 #define VMALLOC_OFFSET (0x1000000) /* 16M */
177 
178 /*
179  * With CONFIG_STRICT_KERNEL_RWX, kernel segments are set NX. But when modules
180  * are used, NX cannot be set on VMALLOC space. So vmalloc VM space and linear
181  * memory shall not share segments.
182  */
183 #if defined(CONFIG_STRICT_KERNEL_RWX) && defined(CONFIG_MODULES)
184 #define VMALLOC_START ((_ALIGN((long)high_memory, 256L << 20) + VMALLOC_OFFSET) & \
185 		       ~(VMALLOC_OFFSET - 1))
186 #else
187 #define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
188 #endif
189 #define VMALLOC_END	ioremap_bot
190 
191 #ifndef __ASSEMBLY__
192 #include <linux/sched.h>
193 #include <linux/threads.h>
194 
195 extern unsigned long ioremap_bot;
196 
197 /* Bits to mask out from a PGD to get to the PUD page */
198 #define PGD_MASKED_BITS		0
199 
200 #define pte_ERROR(e) \
201 	pr_err("%s:%d: bad pte %llx.\n", __FILE__, __LINE__, \
202 		(unsigned long long)pte_val(e))
203 #define pgd_ERROR(e) \
204 	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
205 /*
206  * Bits in a linux-style PTE.  These match the bits in the
207  * (hardware-defined) PowerPC PTE as closely as possible.
208  */
209 
210 #define pte_clear(mm, addr, ptep) \
211 	do { pte_update(ptep, ~_PAGE_HASHPTE, 0); } while (0)
212 
213 #define pmd_none(pmd)		(!pmd_val(pmd))
214 #define	pmd_bad(pmd)		(pmd_val(pmd) & _PMD_BAD)
215 #define	pmd_present(pmd)	(pmd_val(pmd) & _PMD_PRESENT_MASK)
216 static inline void pmd_clear(pmd_t *pmdp)
217 {
218 	*pmdp = __pmd(0);
219 }
220 
221 
222 /*
223  * When flushing the tlb entry for a page, we also need to flush the hash
224  * table entry.  flush_hash_pages is assembler (for speed) in hashtable.S.
225  */
226 extern int flush_hash_pages(unsigned context, unsigned long va,
227 			    unsigned long pmdval, int count);
228 
229 /* Add an HPTE to the hash table */
230 extern void add_hash_page(unsigned context, unsigned long va,
231 			  unsigned long pmdval);
232 
233 /* Flush an entry from the TLB/hash table */
234 extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
235 			     unsigned long address);
236 
237 /*
238  * PTE updates. This function is called whenever an existing
239  * valid PTE is updated. This does -not- include set_pte_at()
240  * which nowadays only sets a new PTE.
241  *
242  * Depending on the type of MMU, we may need to use atomic updates
243  * and the PTE may be either 32 or 64 bit wide. In the later case,
244  * when using atomic updates, only the low part of the PTE is
245  * accessed atomically.
246  *
247  * In addition, on 44x, we also maintain a global flag indicating
248  * that an executable user mapping was modified, which is needed
249  * to properly flush the virtually tagged instruction cache of
250  * those implementations.
251  */
252 #ifndef CONFIG_PTE_64BIT
253 static inline unsigned long pte_update(pte_t *p,
254 				       unsigned long clr,
255 				       unsigned long set)
256 {
257 	unsigned long old, tmp;
258 
259 	__asm__ __volatile__("\
260 1:	lwarx	%0,0,%3\n\
261 	andc	%1,%0,%4\n\
262 	or	%1,%1,%5\n"
263 "	stwcx.	%1,0,%3\n\
264 	bne-	1b"
265 	: "=&r" (old), "=&r" (tmp), "=m" (*p)
266 	: "r" (p), "r" (clr), "r" (set), "m" (*p)
267 	: "cc" );
268 
269 	return old;
270 }
271 #else /* CONFIG_PTE_64BIT */
272 static inline unsigned long long pte_update(pte_t *p,
273 					    unsigned long clr,
274 					    unsigned long set)
275 {
276 	unsigned long long old;
277 	unsigned long tmp;
278 
279 	__asm__ __volatile__("\
280 1:	lwarx	%L0,0,%4\n\
281 	lwzx	%0,0,%3\n\
282 	andc	%1,%L0,%5\n\
283 	or	%1,%1,%6\n"
284 "	stwcx.	%1,0,%4\n\
285 	bne-	1b"
286 	: "=&r" (old), "=&r" (tmp), "=m" (*p)
287 	: "r" (p), "r" ((unsigned long)(p) + 4), "r" (clr), "r" (set), "m" (*p)
288 	: "cc" );
289 
290 	return old;
291 }
292 #endif /* CONFIG_PTE_64BIT */
293 
294 /*
295  * 2.6 calls this without flushing the TLB entry; this is wrong
296  * for our hash-based implementation, we fix that up here.
297  */
298 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
299 static inline int __ptep_test_and_clear_young(unsigned int context, unsigned long addr, pte_t *ptep)
300 {
301 	unsigned long old;
302 	old = pte_update(ptep, _PAGE_ACCESSED, 0);
303 	if (old & _PAGE_HASHPTE) {
304 		unsigned long ptephys = __pa(ptep) & PAGE_MASK;
305 		flush_hash_pages(context, addr, ptephys, 1);
306 	}
307 	return (old & _PAGE_ACCESSED) != 0;
308 }
309 #define ptep_test_and_clear_young(__vma, __addr, __ptep) \
310 	__ptep_test_and_clear_young((__vma)->vm_mm->context.id, __addr, __ptep)
311 
312 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
313 static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
314 				       pte_t *ptep)
315 {
316 	return __pte(pte_update(ptep, ~_PAGE_HASHPTE, 0));
317 }
318 
319 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
320 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
321 				      pte_t *ptep)
322 {
323 	pte_update(ptep, _PAGE_RW, 0);
324 }
325 
326 static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
327 					   pte_t *ptep, pte_t entry,
328 					   unsigned long address,
329 					   int psize)
330 {
331 	unsigned long set = pte_val(entry) &
332 		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
333 
334 	pte_update(ptep, 0, set);
335 
336 	flush_tlb_page(vma, address);
337 }
338 
339 #define __HAVE_ARCH_PTE_SAME
340 #define pte_same(A,B)	(((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)
341 
342 #define pmd_page_vaddr(pmd)	\
343 	((unsigned long)__va(pmd_val(pmd) & ~(PTE_TABLE_SIZE - 1)))
344 #define pmd_page(pmd)		\
345 	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
346 
347 /* to find an entry in a kernel page-table-directory */
348 #define pgd_offset_k(address) pgd_offset(&init_mm, address)
349 
350 /* to find an entry in a page-table-directory */
351 #define pgd_index(address)	 ((address) >> PGDIR_SHIFT)
352 #define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))
353 
354 /* Find an entry in the third-level page table.. */
355 #define pte_index(address)		\
356 	(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
357 #define pte_offset_kernel(dir, addr)	\
358 	((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(addr))
359 #define pte_offset_map(dir, addr)		\
360 	((pte_t *)(kmap_atomic(pmd_page(*(dir))) + \
361 		   (pmd_page_vaddr(*(dir)) & ~PAGE_MASK)) + pte_index(addr))
362 #define pte_unmap(pte)		kunmap_atomic(pte)
363 
364 /*
365  * Encode and decode a swap entry.
366  * Note that the bits we use in a PTE for representing a swap entry
367  * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used).
368  *   -- paulus
369  */
370 #define __swp_type(entry)		((entry).val & 0x1f)
371 #define __swp_offset(entry)		((entry).val >> 5)
372 #define __swp_entry(type, offset)	((swp_entry_t) { (type) | ((offset) << 5) })
373 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
374 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })
375 
376 int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
377 
378 /* Generic accessors to PTE bits */
379 static inline int pte_write(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_RW);}
380 static inline int pte_read(pte_t pte)		{ return 1; }
381 static inline int pte_dirty(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_DIRTY); }
382 static inline int pte_young(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_ACCESSED); }
383 static inline int pte_special(pte_t pte)	{ return !!(pte_val(pte) & _PAGE_SPECIAL); }
384 static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
385 static inline bool pte_exec(pte_t pte)		{ return pte_val(pte) & _PAGE_EXEC; }
386 
387 static inline int pte_present(pte_t pte)
388 {
389 	return pte_val(pte) & _PAGE_PRESENT;
390 }
391 
392 static inline bool pte_hw_valid(pte_t pte)
393 {
394 	return pte_val(pte) & _PAGE_PRESENT;
395 }
396 
397 static inline bool pte_hashpte(pte_t pte)
398 {
399 	return !!(pte_val(pte) & _PAGE_HASHPTE);
400 }
401 
402 static inline bool pte_ci(pte_t pte)
403 {
404 	return !!(pte_val(pte) & _PAGE_NO_CACHE);
405 }
406 
407 /*
408  * We only find page table entry in the last level
409  * Hence no need for other accessors
410  */
411 #define pte_access_permitted pte_access_permitted
412 static inline bool pte_access_permitted(pte_t pte, bool write)
413 {
414 	/*
415 	 * A read-only access is controlled by _PAGE_USER bit.
416 	 * We have _PAGE_READ set for WRITE and EXECUTE
417 	 */
418 	if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte))
419 		return false;
420 
421 	if (write && !pte_write(pte))
422 		return false;
423 
424 	return true;
425 }
426 
427 /* Conversion functions: convert a page and protection to a page entry,
428  * and a page entry and page directory to the page they refer to.
429  *
430  * Even if PTEs can be unsigned long long, a PFN is always an unsigned
431  * long for now.
432  */
433 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
434 {
435 	return __pte(((pte_basic_t)(pfn) << PTE_RPN_SHIFT) |
436 		     pgprot_val(pgprot));
437 }
438 
439 static inline unsigned long pte_pfn(pte_t pte)
440 {
441 	return pte_val(pte) >> PTE_RPN_SHIFT;
442 }
443 
444 /* Generic modifiers for PTE bits */
445 static inline pte_t pte_wrprotect(pte_t pte)
446 {
447 	return __pte(pte_val(pte) & ~_PAGE_RW);
448 }
449 
450 static inline pte_t pte_exprotect(pte_t pte)
451 {
452 	return __pte(pte_val(pte) & ~_PAGE_EXEC);
453 }
454 
455 static inline pte_t pte_mkclean(pte_t pte)
456 {
457 	return __pte(pte_val(pte) & ~_PAGE_DIRTY);
458 }
459 
460 static inline pte_t pte_mkold(pte_t pte)
461 {
462 	return __pte(pte_val(pte) & ~_PAGE_ACCESSED);
463 }
464 
465 static inline pte_t pte_mkexec(pte_t pte)
466 {
467 	return __pte(pte_val(pte) | _PAGE_EXEC);
468 }
469 
470 static inline pte_t pte_mkpte(pte_t pte)
471 {
472 	return pte;
473 }
474 
475 static inline pte_t pte_mkwrite(pte_t pte)
476 {
477 	return __pte(pte_val(pte) | _PAGE_RW);
478 }
479 
480 static inline pte_t pte_mkdirty(pte_t pte)
481 {
482 	return __pte(pte_val(pte) | _PAGE_DIRTY);
483 }
484 
485 static inline pte_t pte_mkyoung(pte_t pte)
486 {
487 	return __pte(pte_val(pte) | _PAGE_ACCESSED);
488 }
489 
490 static inline pte_t pte_mkspecial(pte_t pte)
491 {
492 	return __pte(pte_val(pte) | _PAGE_SPECIAL);
493 }
494 
495 static inline pte_t pte_mkhuge(pte_t pte)
496 {
497 	return pte;
498 }
499 
500 static inline pte_t pte_mkprivileged(pte_t pte)
501 {
502 	return __pte(pte_val(pte) & ~_PAGE_USER);
503 }
504 
505 static inline pte_t pte_mkuser(pte_t pte)
506 {
507 	return __pte(pte_val(pte) | _PAGE_USER);
508 }
509 
510 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
511 {
512 	return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
513 }
514 
515 
516 
517 /* This low level function performs the actual PTE insertion
518  * Setting the PTE depends on the MMU type and other factors. It's
519  * an horrible mess that I'm not going to try to clean up now but
520  * I'm keeping it in one place rather than spread around
521  */
522 static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
523 				pte_t *ptep, pte_t pte, int percpu)
524 {
525 #if defined(CONFIG_SMP) && !defined(CONFIG_PTE_64BIT)
526 	/* First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
527 	 * helper pte_update() which does an atomic update. We need to do that
528 	 * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
529 	 * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
530 	 * the hash bits instead (ie, same as the non-SMP case)
531 	 */
532 	if (percpu)
533 		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
534 			      | (pte_val(pte) & ~_PAGE_HASHPTE));
535 	else
536 		pte_update(ptep, ~_PAGE_HASHPTE, pte_val(pte));
537 
538 #elif defined(CONFIG_PTE_64BIT)
539 	/* Second case is 32-bit with 64-bit PTE.  In this case, we
540 	 * can just store as long as we do the two halves in the right order
541 	 * with a barrier in between. This is possible because we take care,
542 	 * in the hash code, to pre-invalidate if the PTE was already hashed,
543 	 * which synchronizes us with any concurrent invalidation.
544 	 * In the percpu case, we also fallback to the simple update preserving
545 	 * the hash bits
546 	 */
547 	if (percpu) {
548 		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
549 			      | (pte_val(pte) & ~_PAGE_HASHPTE));
550 		return;
551 	}
552 	if (pte_val(*ptep) & _PAGE_HASHPTE)
553 		flush_hash_entry(mm, ptep, addr);
554 	__asm__ __volatile__("\
555 		stw%U0%X0 %2,%0\n\
556 		eieio\n\
557 		stw%U0%X0 %L2,%1"
558 	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
559 	: "r" (pte) : "memory");
560 
561 #else
562 	/* Third case is 32-bit hash table in UP mode, we need to preserve
563 	 * the _PAGE_HASHPTE bit since we may not have invalidated the previous
564 	 * translation in the hash yet (done in a subsequent flush_tlb_xxx())
565 	 * and see we need to keep track that this PTE needs invalidating
566 	 */
567 	*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
568 		      | (pte_val(pte) & ~_PAGE_HASHPTE));
569 #endif
570 }
571 
572 /*
573  * Macro to mark a page protection value as "uncacheable".
574  */
575 
576 #define _PAGE_CACHE_CTL	(_PAGE_COHERENT | _PAGE_GUARDED | _PAGE_NO_CACHE | \
577 			 _PAGE_WRITETHRU)
578 
579 #define pgprot_noncached pgprot_noncached
580 static inline pgprot_t pgprot_noncached(pgprot_t prot)
581 {
582 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
583 			_PAGE_NO_CACHE | _PAGE_GUARDED);
584 }
585 
586 #define pgprot_noncached_wc pgprot_noncached_wc
587 static inline pgprot_t pgprot_noncached_wc(pgprot_t prot)
588 {
589 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
590 			_PAGE_NO_CACHE);
591 }
592 
593 #define pgprot_cached pgprot_cached
594 static inline pgprot_t pgprot_cached(pgprot_t prot)
595 {
596 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
597 			_PAGE_COHERENT);
598 }
599 
600 #define pgprot_cached_wthru pgprot_cached_wthru
601 static inline pgprot_t pgprot_cached_wthru(pgprot_t prot)
602 {
603 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
604 			_PAGE_COHERENT | _PAGE_WRITETHRU);
605 }
606 
607 #define pgprot_cached_noncoherent pgprot_cached_noncoherent
608 static inline pgprot_t pgprot_cached_noncoherent(pgprot_t prot)
609 {
610 	return __pgprot(pgprot_val(prot) & ~_PAGE_CACHE_CTL);
611 }
612 
613 #define pgprot_writecombine pgprot_writecombine
614 static inline pgprot_t pgprot_writecombine(pgprot_t prot)
615 {
616 	return pgprot_noncached_wc(prot);
617 }
618 
619 #endif /* !__ASSEMBLY__ */
620 
621 #endif /*  _ASM_POWERPC_BOOK3S_32_PGTABLE_H */
622