xref: /linux/arch/powerpc/include/asm/book3s/32/pgtable.h (revision a4eb44a6435d6d8f9e642407a4a06f65eb90ca04)
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 | \
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 
180 int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
181 void unmap_kernel_page(unsigned long va);
182 
183 #endif /* !__ASSEMBLY__ */
184 
185 /*
186  * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
187  * value (for now) on others, from where we can start layout kernel
188  * virtual space that goes below PKMAP and FIXMAP
189  */
190 #include <asm/fixmap.h>
191 
192 /*
193  * ioremap_bot starts at that address. Early ioremaps move down from there,
194  * until mem_init() at which point this becomes the top of the vmalloc
195  * and ioremap space
196  */
197 #ifdef CONFIG_HIGHMEM
198 #define IOREMAP_TOP	PKMAP_BASE
199 #else
200 #define IOREMAP_TOP	FIXADDR_START
201 #endif
202 
203 /* PPC32 shares vmalloc area with ioremap */
204 #define IOREMAP_START	VMALLOC_START
205 #define IOREMAP_END	VMALLOC_END
206 
207 /*
208  * Just any arbitrary offset to the start of the vmalloc VM area: the
209  * current 16MB value just means that there will be a 64MB "hole" after the
210  * physical memory until the kernel virtual memory starts.  That means that
211  * any out-of-bounds memory accesses will hopefully be caught.
212  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
213  * area for the same reason. ;)
214  *
215  * We no longer map larger than phys RAM with the BATs so we don't have
216  * to worry about the VMALLOC_OFFSET causing problems.  We do have to worry
217  * about clashes between our early calls to ioremap() that start growing down
218  * from ioremap_base being run into the VM area allocations (growing upwards
219  * from VMALLOC_START).  For this reason we have ioremap_bot to check when
220  * we actually run into our mappings setup in the early boot with the VM
221  * system.  This really does become a problem for machines with good amounts
222  * of RAM.  -- Cort
223  */
224 #define VMALLOC_OFFSET (0x1000000) /* 16M */
225 
226 #define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
227 
228 #ifdef CONFIG_KASAN_VMALLOC
229 #define VMALLOC_END	ALIGN_DOWN(ioremap_bot, PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
230 #else
231 #define VMALLOC_END	ioremap_bot
232 #endif
233 
234 #define MODULES_END	ALIGN_DOWN(PAGE_OFFSET, SZ_256M)
235 #define MODULES_VADDR	(MODULES_END - SZ_256M)
236 
237 #ifndef __ASSEMBLY__
238 #include <linux/sched.h>
239 #include <linux/threads.h>
240 
241 /* Bits to mask out from a PGD to get to the PUD page */
242 #define PGD_MASKED_BITS		0
243 
244 #define pte_ERROR(e) \
245 	pr_err("%s:%d: bad pte %llx.\n", __FILE__, __LINE__, \
246 		(unsigned long long)pte_val(e))
247 #define pgd_ERROR(e) \
248 	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
249 /*
250  * Bits in a linux-style PTE.  These match the bits in the
251  * (hardware-defined) PowerPC PTE as closely as possible.
252  */
253 
254 #define pte_clear(mm, addr, ptep) \
255 	do { pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0); } while (0)
256 
257 #define pmd_none(pmd)		(!pmd_val(pmd))
258 #define	pmd_bad(pmd)		(pmd_val(pmd) & _PMD_BAD)
259 #define	pmd_present(pmd)	(pmd_val(pmd) & _PMD_PRESENT_MASK)
260 static inline void pmd_clear(pmd_t *pmdp)
261 {
262 	*pmdp = __pmd(0);
263 }
264 
265 
266 /*
267  * When flushing the tlb entry for a page, we also need to flush the hash
268  * table entry.  flush_hash_pages is assembler (for speed) in hashtable.S.
269  */
270 extern int flush_hash_pages(unsigned context, unsigned long va,
271 			    unsigned long pmdval, int count);
272 
273 /* Add an HPTE to the hash table */
274 extern void add_hash_page(unsigned context, unsigned long va,
275 			  unsigned long pmdval);
276 
277 /* Flush an entry from the TLB/hash table */
278 static inline void flush_hash_entry(struct mm_struct *mm, pte_t *ptep, unsigned long addr)
279 {
280 	if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
281 		unsigned long ptephys = __pa(ptep) & PAGE_MASK;
282 
283 		flush_hash_pages(mm->context.id, addr, ptephys, 1);
284 	}
285 }
286 
287 /*
288  * PTE updates. This function is called whenever an existing
289  * valid PTE is updated. This does -not- include set_pte_at()
290  * which nowadays only sets a new PTE.
291  *
292  * Depending on the type of MMU, we may need to use atomic updates
293  * and the PTE may be either 32 or 64 bit wide. In the later case,
294  * when using atomic updates, only the low part of the PTE is
295  * accessed atomically.
296  */
297 static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
298 				     unsigned long clr, unsigned long set, int huge)
299 {
300 	pte_basic_t old;
301 	unsigned long tmp;
302 
303 	__asm__ __volatile__(
304 #ifndef CONFIG_PTE_64BIT
305 "1:	lwarx	%0, 0, %3\n"
306 "	andc	%1, %0, %4\n"
307 #else
308 "1:	lwarx	%L0, 0, %3\n"
309 "	lwz	%0, -4(%3)\n"
310 "	andc	%1, %L0, %4\n"
311 #endif
312 "	or	%1, %1, %5\n"
313 "	stwcx.	%1, 0, %3\n"
314 "	bne-	1b"
315 	: "=&r" (old), "=&r" (tmp), "=m" (*p)
316 #ifndef CONFIG_PTE_64BIT
317 	: "r" (p),
318 #else
319 	: "b" ((unsigned long)(p) + 4),
320 #endif
321 	  "r" (clr), "r" (set), "m" (*p)
322 	: "cc" );
323 
324 	return old;
325 }
326 
327 /*
328  * 2.6 calls this without flushing the TLB entry; this is wrong
329  * for our hash-based implementation, we fix that up here.
330  */
331 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
332 static inline int __ptep_test_and_clear_young(struct mm_struct *mm,
333 					      unsigned long addr, pte_t *ptep)
334 {
335 	unsigned long old;
336 	old = pte_update(mm, addr, ptep, _PAGE_ACCESSED, 0, 0);
337 	if (old & _PAGE_HASHPTE)
338 		flush_hash_entry(mm, ptep, addr);
339 
340 	return (old & _PAGE_ACCESSED) != 0;
341 }
342 #define ptep_test_and_clear_young(__vma, __addr, __ptep) \
343 	__ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep)
344 
345 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
346 static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
347 				       pte_t *ptep)
348 {
349 	return __pte(pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, 0, 0));
350 }
351 
352 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
353 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
354 				      pte_t *ptep)
355 {
356 	pte_update(mm, addr, ptep, _PAGE_RW, 0, 0);
357 }
358 
359 static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
360 					   pte_t *ptep, pte_t entry,
361 					   unsigned long address,
362 					   int psize)
363 {
364 	unsigned long set = pte_val(entry) &
365 		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
366 
367 	pte_update(vma->vm_mm, address, ptep, 0, set, 0);
368 
369 	flush_tlb_page(vma, address);
370 }
371 
372 #define __HAVE_ARCH_PTE_SAME
373 #define pte_same(A,B)	(((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)
374 
375 #define pmd_page(pmd)		\
376 	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
377 
378 /*
379  * Encode and decode a swap entry.
380  * Note that the bits we use in a PTE for representing a swap entry
381  * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used).
382  *   -- paulus
383  */
384 #define __swp_type(entry)		((entry).val & 0x1f)
385 #define __swp_offset(entry)		((entry).val >> 5)
386 #define __swp_entry(type, offset)	((swp_entry_t) { (type) | ((offset) << 5) })
387 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
388 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })
389 
390 /* Generic accessors to PTE bits */
391 static inline int pte_write(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_RW);}
392 static inline int pte_read(pte_t pte)		{ return 1; }
393 static inline int pte_dirty(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_DIRTY); }
394 static inline int pte_young(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_ACCESSED); }
395 static inline int pte_special(pte_t pte)	{ return !!(pte_val(pte) & _PAGE_SPECIAL); }
396 static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
397 static inline bool pte_exec(pte_t pte)		{ return pte_val(pte) & _PAGE_EXEC; }
398 
399 static inline int pte_present(pte_t pte)
400 {
401 	return pte_val(pte) & _PAGE_PRESENT;
402 }
403 
404 static inline bool pte_hw_valid(pte_t pte)
405 {
406 	return pte_val(pte) & _PAGE_PRESENT;
407 }
408 
409 static inline bool pte_hashpte(pte_t pte)
410 {
411 	return !!(pte_val(pte) & _PAGE_HASHPTE);
412 }
413 
414 static inline bool pte_ci(pte_t pte)
415 {
416 	return !!(pte_val(pte) & _PAGE_NO_CACHE);
417 }
418 
419 /*
420  * We only find page table entry in the last level
421  * Hence no need for other accessors
422  */
423 #define pte_access_permitted pte_access_permitted
424 static inline bool pte_access_permitted(pte_t pte, bool write)
425 {
426 	/*
427 	 * A read-only access is controlled by _PAGE_USER bit.
428 	 * We have _PAGE_READ set for WRITE and EXECUTE
429 	 */
430 	if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte))
431 		return false;
432 
433 	if (write && !pte_write(pte))
434 		return false;
435 
436 	return true;
437 }
438 
439 /* Conversion functions: convert a page and protection to a page entry,
440  * and a page entry and page directory to the page they refer to.
441  *
442  * Even if PTEs can be unsigned long long, a PFN is always an unsigned
443  * long for now.
444  */
445 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
446 {
447 	return __pte(((pte_basic_t)(pfn) << PTE_RPN_SHIFT) |
448 		     pgprot_val(pgprot));
449 }
450 
451 static inline unsigned long pte_pfn(pte_t pte)
452 {
453 	return pte_val(pte) >> PTE_RPN_SHIFT;
454 }
455 
456 /* Generic modifiers for PTE bits */
457 static inline pte_t pte_wrprotect(pte_t pte)
458 {
459 	return __pte(pte_val(pte) & ~_PAGE_RW);
460 }
461 
462 static inline pte_t pte_exprotect(pte_t pte)
463 {
464 	return __pte(pte_val(pte) & ~_PAGE_EXEC);
465 }
466 
467 static inline pte_t pte_mkclean(pte_t pte)
468 {
469 	return __pte(pte_val(pte) & ~_PAGE_DIRTY);
470 }
471 
472 static inline pte_t pte_mkold(pte_t pte)
473 {
474 	return __pte(pte_val(pte) & ~_PAGE_ACCESSED);
475 }
476 
477 static inline pte_t pte_mkexec(pte_t pte)
478 {
479 	return __pte(pte_val(pte) | _PAGE_EXEC);
480 }
481 
482 static inline pte_t pte_mkpte(pte_t pte)
483 {
484 	return pte;
485 }
486 
487 static inline pte_t pte_mkwrite(pte_t pte)
488 {
489 	return __pte(pte_val(pte) | _PAGE_RW);
490 }
491 
492 static inline pte_t pte_mkdirty(pte_t pte)
493 {
494 	return __pte(pte_val(pte) | _PAGE_DIRTY);
495 }
496 
497 static inline pte_t pte_mkyoung(pte_t pte)
498 {
499 	return __pte(pte_val(pte) | _PAGE_ACCESSED);
500 }
501 
502 static inline pte_t pte_mkspecial(pte_t pte)
503 {
504 	return __pte(pte_val(pte) | _PAGE_SPECIAL);
505 }
506 
507 static inline pte_t pte_mkhuge(pte_t pte)
508 {
509 	return pte;
510 }
511 
512 static inline pte_t pte_mkprivileged(pte_t pte)
513 {
514 	return __pte(pte_val(pte) & ~_PAGE_USER);
515 }
516 
517 static inline pte_t pte_mkuser(pte_t pte)
518 {
519 	return __pte(pte_val(pte) | _PAGE_USER);
520 }
521 
522 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
523 {
524 	return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
525 }
526 
527 
528 
529 /* This low level function performs the actual PTE insertion
530  * Setting the PTE depends on the MMU type and other factors. It's
531  * an horrible mess that I'm not going to try to clean up now but
532  * I'm keeping it in one place rather than spread around
533  */
534 static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
535 				pte_t *ptep, pte_t pte, int percpu)
536 {
537 #if defined(CONFIG_SMP) && !defined(CONFIG_PTE_64BIT)
538 	/* First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
539 	 * helper pte_update() which does an atomic update. We need to do that
540 	 * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
541 	 * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
542 	 * the hash bits instead (ie, same as the non-SMP case)
543 	 */
544 	if (percpu)
545 		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
546 			      | (pte_val(pte) & ~_PAGE_HASHPTE));
547 	else
548 		pte_update(mm, addr, ptep, ~_PAGE_HASHPTE, pte_val(pte), 0);
549 
550 #elif defined(CONFIG_PTE_64BIT)
551 	/* Second case is 32-bit with 64-bit PTE.  In this case, we
552 	 * can just store as long as we do the two halves in the right order
553 	 * with a barrier in between. This is possible because we take care,
554 	 * in the hash code, to pre-invalidate if the PTE was already hashed,
555 	 * which synchronizes us with any concurrent invalidation.
556 	 * In the percpu case, we also fallback to the simple update preserving
557 	 * the hash bits
558 	 */
559 	if (percpu) {
560 		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
561 			      | (pte_val(pte) & ~_PAGE_HASHPTE));
562 		return;
563 	}
564 	if (pte_val(*ptep) & _PAGE_HASHPTE)
565 		flush_hash_entry(mm, ptep, addr);
566 	__asm__ __volatile__("\
567 		stw%X0 %2,%0\n\
568 		eieio\n\
569 		stw%X1 %L2,%1"
570 	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
571 	: "r" (pte) : "memory");
572 
573 #else
574 	/* Third case is 32-bit hash table in UP mode, we need to preserve
575 	 * the _PAGE_HASHPTE bit since we may not have invalidated the previous
576 	 * translation in the hash yet (done in a subsequent flush_tlb_xxx())
577 	 * and see we need to keep track that this PTE needs invalidating
578 	 */
579 	*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
580 		      | (pte_val(pte) & ~_PAGE_HASHPTE));
581 #endif
582 }
583 
584 /*
585  * Macro to mark a page protection value as "uncacheable".
586  */
587 
588 #define _PAGE_CACHE_CTL	(_PAGE_COHERENT | _PAGE_GUARDED | _PAGE_NO_CACHE | \
589 			 _PAGE_WRITETHRU)
590 
591 #define pgprot_noncached pgprot_noncached
592 static inline pgprot_t pgprot_noncached(pgprot_t prot)
593 {
594 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
595 			_PAGE_NO_CACHE | _PAGE_GUARDED);
596 }
597 
598 #define pgprot_noncached_wc pgprot_noncached_wc
599 static inline pgprot_t pgprot_noncached_wc(pgprot_t prot)
600 {
601 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
602 			_PAGE_NO_CACHE);
603 }
604 
605 #define pgprot_cached pgprot_cached
606 static inline pgprot_t pgprot_cached(pgprot_t prot)
607 {
608 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
609 			_PAGE_COHERENT);
610 }
611 
612 #define pgprot_cached_wthru pgprot_cached_wthru
613 static inline pgprot_t pgprot_cached_wthru(pgprot_t prot)
614 {
615 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
616 			_PAGE_COHERENT | _PAGE_WRITETHRU);
617 }
618 
619 #define pgprot_cached_noncoherent pgprot_cached_noncoherent
620 static inline pgprot_t pgprot_cached_noncoherent(pgprot_t prot)
621 {
622 	return __pgprot(pgprot_val(prot) & ~_PAGE_CACHE_CTL);
623 }
624 
625 #define pgprot_writecombine pgprot_writecombine
626 static inline pgprot_t pgprot_writecombine(pgprot_t prot)
627 {
628 	return pgprot_noncached_wc(prot);
629 }
630 
631 #endif /* !__ASSEMBLY__ */
632 
633 #endif /*  _ASM_POWERPC_BOOK3S_32_PGTABLE_H */
634