xref: /openbmc/linux/arch/sh/include/asm/pgtable_32.h (revision 86e281fc)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_SH_PGTABLE_32_H
3 #define __ASM_SH_PGTABLE_32_H
4 
5 /*
6  * Linux PTEL encoding.
7  *
8  * Hardware and software bit definitions for the PTEL value (see below for
9  * notes on SH-X2 MMUs and 64-bit PTEs):
10  *
11  * - Bits 0 and 7 are reserved on SH-3 (_PAGE_WT and _PAGE_SZ1 on SH-4).
12  *
13  * - Bit 1 is the SH-bit, but is unused on SH-3 due to an MMU bug (the
14  *   hardware PTEL value can't have the SH-bit set when MMUCR.IX is set,
15  *   which is the default in cpu-sh3/mmu_context.h:MMU_CONTROL_INIT).
16  *
17  *   In order to keep this relatively clean, do not use these for defining
18  *   SH-3 specific flags until all of the other unused bits have been
19  *   exhausted.
20  *
21  * - Bit 9 is reserved by everyone and used by _PAGE_PROTNONE.
22  *
23  * - Bits 10 and 11 are low bits of the PPN that are reserved on >= 4K pages.
24  *   Bit 10 is used for _PAGE_ACCESSED, and bit 11 is used for _PAGE_SPECIAL.
25  *
26  * - On 29 bit platforms, bits 31 to 29 are used for the space attributes
27  *   and timing control which (together with bit 0) are moved into the
28  *   old-style PTEA on the parts that support it.
29  *
30  * SH-X2 MMUs and extended PTEs
31  *
32  * SH-X2 supports an extended mode TLB with split data arrays due to the
33  * number of bits needed for PR and SZ (now EPR and ESZ) encodings. The PR and
34  * SZ bit placeholders still exist in data array 1, but are implemented as
35  * reserved bits, with the real logic existing in data array 2.
36  *
37  * The downside to this is that we can no longer fit everything in to a 32-bit
38  * PTE encoding, so a 64-bit pte_t is necessary for these parts. On the plus
39  * side, this gives us quite a few spare bits to play with for future usage.
40  */
41 /* Legacy and compat mode bits */
42 #define	_PAGE_WT	0x001		/* WT-bit on SH-4, 0 on SH-3 */
43 #define _PAGE_HW_SHARED	0x002		/* SH-bit  : shared among processes */
44 #define _PAGE_DIRTY	0x004		/* D-bit   : page changed */
45 #define _PAGE_CACHABLE	0x008		/* C-bit   : cachable */
46 #define _PAGE_SZ0	0x010		/* SZ0-bit : Size of page */
47 #define _PAGE_RW	0x020		/* PR0-bit : write access allowed */
48 #define _PAGE_USER	0x040		/* PR1-bit : user space access allowed*/
49 #define _PAGE_SZ1	0x080		/* SZ1-bit : Size of page (on SH-4) */
50 #define _PAGE_PRESENT	0x100		/* V-bit   : page is valid */
51 #define _PAGE_PROTNONE	0x200		/* software: if not present  */
52 #define _PAGE_ACCESSED	0x400		/* software: page referenced */
53 #define _PAGE_SPECIAL	0x800		/* software: special page */
54 
55 #define _PAGE_SZ_MASK	(_PAGE_SZ0 | _PAGE_SZ1)
56 #define _PAGE_PR_MASK	(_PAGE_RW | _PAGE_USER)
57 
58 /* Extended mode bits */
59 #define _PAGE_EXT_ESZ0		0x0010	/* ESZ0-bit: Size of page */
60 #define _PAGE_EXT_ESZ1		0x0020	/* ESZ1-bit: Size of page */
61 #define _PAGE_EXT_ESZ2		0x0040	/* ESZ2-bit: Size of page */
62 #define _PAGE_EXT_ESZ3		0x0080	/* ESZ3-bit: Size of page */
63 
64 #define _PAGE_EXT_USER_EXEC	0x0100	/* EPR0-bit: User space executable */
65 #define _PAGE_EXT_USER_WRITE	0x0200	/* EPR1-bit: User space writable */
66 #define _PAGE_EXT_USER_READ	0x0400	/* EPR2-bit: User space readable */
67 
68 #define _PAGE_EXT_KERN_EXEC	0x0800	/* EPR3-bit: Kernel space executable */
69 #define _PAGE_EXT_KERN_WRITE	0x1000	/* EPR4-bit: Kernel space writable */
70 #define _PAGE_EXT_KERN_READ	0x2000	/* EPR5-bit: Kernel space readable */
71 
72 #define _PAGE_EXT_WIRED		0x4000	/* software: Wire TLB entry */
73 
74 /* Wrapper for extended mode pgprot twiddling */
75 #define _PAGE_EXT(x)		((unsigned long long)(x) << 32)
76 
77 #ifdef CONFIG_X2TLB
78 #define _PAGE_PCC_MASK	0x00000000	/* No legacy PTEA support */
79 #else
80 
81 /* software: moves to PTEA.TC (Timing Control) */
82 #define _PAGE_PCC_AREA5	0x00000000	/* use BSC registers for area5 */
83 #define _PAGE_PCC_AREA6	0x80000000	/* use BSC registers for area6 */
84 
85 /* software: moves to PTEA.SA[2:0] (Space Attributes) */
86 #define _PAGE_PCC_IODYN 0x00000001	/* IO space, dynamically sized bus */
87 #define _PAGE_PCC_IO8	0x20000000	/* IO space, 8 bit bus */
88 #define _PAGE_PCC_IO16	0x20000001	/* IO space, 16 bit bus */
89 #define _PAGE_PCC_COM8	0x40000000	/* Common Memory space, 8 bit bus */
90 #define _PAGE_PCC_COM16	0x40000001	/* Common Memory space, 16 bit bus */
91 #define _PAGE_PCC_ATR8	0x60000000	/* Attribute Memory space, 8 bit bus */
92 #define _PAGE_PCC_ATR16	0x60000001	/* Attribute Memory space, 6 bit bus */
93 
94 #define _PAGE_PCC_MASK	0xe0000001
95 
96 /* copy the ptea attributes */
97 static inline unsigned long copy_ptea_attributes(unsigned long x)
98 {
99 	return	((x >> 28) & 0xe) | (x & 0x1);
100 }
101 #endif
102 
103 /* Mask which drops unused bits from the PTEL value */
104 #if defined(CONFIG_CPU_SH3)
105 #define _PAGE_CLEAR_FLAGS	(_PAGE_PROTNONE | _PAGE_ACCESSED| \
106 				  _PAGE_SZ1	| _PAGE_HW_SHARED)
107 #elif defined(CONFIG_X2TLB)
108 /* Get rid of the legacy PR/SZ bits when using extended mode */
109 #define _PAGE_CLEAR_FLAGS	(_PAGE_PROTNONE | _PAGE_ACCESSED | \
110 				 _PAGE_PR_MASK | _PAGE_SZ_MASK)
111 #else
112 #define _PAGE_CLEAR_FLAGS	(_PAGE_PROTNONE | _PAGE_ACCESSED)
113 #endif
114 
115 #define _PAGE_FLAGS_HARDWARE_MASK	(phys_addr_mask() & ~(_PAGE_CLEAR_FLAGS))
116 
117 /* Hardware flags, page size encoding */
118 #if !defined(CONFIG_MMU)
119 # define _PAGE_FLAGS_HARD	0ULL
120 #elif defined(CONFIG_X2TLB)
121 # if defined(CONFIG_PAGE_SIZE_4KB)
122 #  define _PAGE_FLAGS_HARD	_PAGE_EXT(_PAGE_EXT_ESZ0)
123 # elif defined(CONFIG_PAGE_SIZE_8KB)
124 #  define _PAGE_FLAGS_HARD	_PAGE_EXT(_PAGE_EXT_ESZ1)
125 # elif defined(CONFIG_PAGE_SIZE_64KB)
126 #  define _PAGE_FLAGS_HARD	_PAGE_EXT(_PAGE_EXT_ESZ2)
127 # endif
128 #else
129 # if defined(CONFIG_PAGE_SIZE_4KB)
130 #  define _PAGE_FLAGS_HARD	_PAGE_SZ0
131 # elif defined(CONFIG_PAGE_SIZE_64KB)
132 #  define _PAGE_FLAGS_HARD	_PAGE_SZ1
133 # endif
134 #endif
135 
136 #if defined(CONFIG_X2TLB)
137 # if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
138 #  define _PAGE_SZHUGE	(_PAGE_EXT_ESZ2)
139 # elif defined(CONFIG_HUGETLB_PAGE_SIZE_256K)
140 #  define _PAGE_SZHUGE	(_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ2)
141 # elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
142 #  define _PAGE_SZHUGE	(_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ1 | _PAGE_EXT_ESZ2)
143 # elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
144 #  define _PAGE_SZHUGE	(_PAGE_EXT_ESZ3)
145 # elif defined(CONFIG_HUGETLB_PAGE_SIZE_64MB)
146 #  define _PAGE_SZHUGE	(_PAGE_EXT_ESZ2 | _PAGE_EXT_ESZ3)
147 # endif
148 # define _PAGE_WIRED	(_PAGE_EXT(_PAGE_EXT_WIRED))
149 #else
150 # if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
151 #  define _PAGE_SZHUGE	(_PAGE_SZ1)
152 # elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
153 #  define _PAGE_SZHUGE	(_PAGE_SZ0 | _PAGE_SZ1)
154 # endif
155 # define _PAGE_WIRED	(0)
156 #endif
157 
158 /*
159  * Stub out _PAGE_SZHUGE if we don't have a good definition for it,
160  * to make pte_mkhuge() happy.
161  */
162 #ifndef _PAGE_SZHUGE
163 # define _PAGE_SZHUGE	(_PAGE_FLAGS_HARD)
164 #endif
165 
166 /*
167  * Mask of bits that are to be preserved across pgprot changes.
168  */
169 #define _PAGE_CHG_MASK \
170 	(PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | \
171 	 _PAGE_DIRTY | _PAGE_SPECIAL)
172 
173 #ifndef __ASSEMBLY__
174 
175 #if defined(CONFIG_X2TLB) /* SH-X2 TLB */
176 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
177 				 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
178 
179 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
180 				 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
181 				 _PAGE_EXT(_PAGE_EXT_KERN_READ  | \
182 					   _PAGE_EXT_KERN_WRITE | \
183 					   _PAGE_EXT_USER_READ  | \
184 					   _PAGE_EXT_USER_WRITE))
185 
186 #define PAGE_EXECREAD	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
187 				 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
188 				 _PAGE_EXT(_PAGE_EXT_KERN_EXEC | \
189 					   _PAGE_EXT_KERN_READ | \
190 					   _PAGE_EXT_USER_EXEC | \
191 					   _PAGE_EXT_USER_READ))
192 
193 #define PAGE_COPY	PAGE_EXECREAD
194 
195 #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
196 				 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
197 				 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
198 					   _PAGE_EXT_USER_READ))
199 
200 #define PAGE_WRITEONLY	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
201 				 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
202 				 _PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
203 					   _PAGE_EXT_USER_WRITE))
204 
205 #define PAGE_RWX	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
206 				 _PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
207 				 _PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
208 					   _PAGE_EXT_KERN_READ  | \
209 					   _PAGE_EXT_KERN_EXEC  | \
210 					   _PAGE_EXT_USER_WRITE | \
211 					   _PAGE_EXT_USER_READ  | \
212 					   _PAGE_EXT_USER_EXEC))
213 
214 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
215 				 _PAGE_DIRTY | _PAGE_ACCESSED | \
216 				 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
217 				 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
218 					   _PAGE_EXT_KERN_WRITE | \
219 					   _PAGE_EXT_KERN_EXEC))
220 
221 #define PAGE_KERNEL_NOCACHE \
222 			__pgprot(_PAGE_PRESENT | _PAGE_DIRTY | \
223 				 _PAGE_ACCESSED | _PAGE_HW_SHARED | \
224 				 _PAGE_FLAGS_HARD | \
225 				 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
226 					   _PAGE_EXT_KERN_WRITE | \
227 					   _PAGE_EXT_KERN_EXEC))
228 
229 #define PAGE_KERNEL_RO	__pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
230 				 _PAGE_DIRTY | _PAGE_ACCESSED | \
231 				 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
232 				 _PAGE_EXT(_PAGE_EXT_KERN_READ | \
233 					   _PAGE_EXT_KERN_EXEC))
234 
235 #define PAGE_KERNEL_PCC(slot, type) \
236 			__pgprot(0)
237 
238 #elif defined(CONFIG_MMU) /* SH-X TLB */
239 #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
240 				 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
241 
242 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \
243 				 _PAGE_CACHABLE | _PAGE_ACCESSED | \
244 				 _PAGE_FLAGS_HARD)
245 
246 #define PAGE_COPY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
247 				 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
248 
249 #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
250 				 _PAGE_ACCESSED | _PAGE_FLAGS_HARD)
251 
252 #define PAGE_EXECREAD	PAGE_READONLY
253 #define PAGE_RWX	PAGE_SHARED
254 #define PAGE_WRITEONLY	PAGE_SHARED
255 
256 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_CACHABLE | \
257 				 _PAGE_DIRTY | _PAGE_ACCESSED | \
258 				 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
259 
260 #define PAGE_KERNEL_NOCACHE \
261 			__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
262 				 _PAGE_ACCESSED | _PAGE_HW_SHARED | \
263 				 _PAGE_FLAGS_HARD)
264 
265 #define PAGE_KERNEL_RO	__pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
266 				 _PAGE_DIRTY | _PAGE_ACCESSED | \
267 				 _PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
268 
269 #define PAGE_KERNEL_PCC(slot, type) \
270 			__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
271 				 _PAGE_ACCESSED | _PAGE_FLAGS_HARD | \
272 				 (slot ? _PAGE_PCC_AREA5 : _PAGE_PCC_AREA6) | \
273 				 (type))
274 #else /* no mmu */
275 #define PAGE_NONE		__pgprot(0)
276 #define PAGE_SHARED		__pgprot(0)
277 #define PAGE_COPY		__pgprot(0)
278 #define PAGE_EXECREAD		__pgprot(0)
279 #define PAGE_RWX		__pgprot(0)
280 #define PAGE_READONLY		__pgprot(0)
281 #define PAGE_WRITEONLY		__pgprot(0)
282 #define PAGE_KERNEL		__pgprot(0)
283 #define PAGE_KERNEL_NOCACHE	__pgprot(0)
284 #define PAGE_KERNEL_RO		__pgprot(0)
285 
286 #define PAGE_KERNEL_PCC(slot, type) \
287 				__pgprot(0)
288 #endif
289 
290 #endif /* __ASSEMBLY__ */
291 
292 #ifndef __ASSEMBLY__
293 
294 /*
295  * Certain architectures need to do special things when PTEs
296  * within a page table are directly modified.  Thus, the following
297  * hook is made available.
298  */
299 #ifdef CONFIG_X2TLB
300 static inline void set_pte(pte_t *ptep, pte_t pte)
301 {
302 	ptep->pte_high = pte.pte_high;
303 	smp_wmb();
304 	ptep->pte_low = pte.pte_low;
305 }
306 #else
307 #define set_pte(pteptr, pteval) (*(pteptr) = pteval)
308 #endif
309 
310 /*
311  * (pmds are folded into pgds so this doesn't get actually called,
312  * but the define is needed for a generic inline function.)
313  */
314 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
315 
316 #define PFN_PTE_SHIFT	PAGE_SHIFT
317 #define pfn_pte(pfn, prot) \
318 	__pte(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
319 #define pfn_pmd(pfn, prot) \
320 	__pmd(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
321 
322 #define pte_none(x)		(!pte_val(x))
323 #define pte_present(x)		((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
324 
325 #define pte_clear(mm, addr, ptep) set_pte(ptep, __pte(0))
326 
327 #define pmd_none(x)	(!pmd_val(x))
328 #define pmd_present(x)	(pmd_val(x))
329 #define pmd_clear(xp)	do { set_pmd(xp, __pmd(0)); } while (0)
330 #define	pmd_bad(x)	(pmd_val(x) & ~PAGE_MASK)
331 
332 #define pages_to_mb(x)	((x) >> (20-PAGE_SHIFT))
333 #define pte_page(x)	pfn_to_page(pte_pfn(x))
334 
335 /*
336  * The following only work if pte_present() is true.
337  * Undefined behaviour if not..
338  */
339 #define pte_not_present(pte)	(!((pte).pte_low & _PAGE_PRESENT))
340 #define pte_dirty(pte)		((pte).pte_low & _PAGE_DIRTY)
341 #define pte_young(pte)		((pte).pte_low & _PAGE_ACCESSED)
342 #define pte_special(pte)	((pte).pte_low & _PAGE_SPECIAL)
343 
344 #ifdef CONFIG_X2TLB
345 #define pte_write(pte) \
346 	((pte).pte_high & (_PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE))
347 #else
348 #define pte_write(pte)		((pte).pte_low & _PAGE_RW)
349 #endif
350 
351 #define PTE_BIT_FUNC(h,fn,op) \
352 static inline pte_t pte_##fn(pte_t pte) { pte.pte_##h op; return pte; }
353 
354 #ifdef CONFIG_X2TLB
355 /*
356  * We cheat a bit in the SH-X2 TLB case. As the permission bits are
357  * individually toggled (and user permissions are entirely decoupled from
358  * kernel permissions), we attempt to couple them a bit more sanely here.
359  */
360 PTE_BIT_FUNC(high, wrprotect, &= ~(_PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE));
361 PTE_BIT_FUNC(high, mkwrite_novma, |= _PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE);
362 PTE_BIT_FUNC(high, mkhuge, |= _PAGE_SZHUGE);
363 #else
364 PTE_BIT_FUNC(low, wrprotect, &= ~_PAGE_RW);
365 PTE_BIT_FUNC(low, mkwrite_novma, |= _PAGE_RW);
366 PTE_BIT_FUNC(low, mkhuge, |= _PAGE_SZHUGE);
367 #endif
368 
369 PTE_BIT_FUNC(low, mkclean, &= ~_PAGE_DIRTY);
370 PTE_BIT_FUNC(low, mkdirty, |= _PAGE_DIRTY);
371 PTE_BIT_FUNC(low, mkold, &= ~_PAGE_ACCESSED);
372 PTE_BIT_FUNC(low, mkyoung, |= _PAGE_ACCESSED);
373 PTE_BIT_FUNC(low, mkspecial, |= _PAGE_SPECIAL);
374 
375 /*
376  * Macro and implementation to make a page protection as uncachable.
377  */
378 #define pgprot_writecombine(prot) \
379 	__pgprot(pgprot_val(prot) & ~_PAGE_CACHABLE)
380 
381 #define pgprot_noncached	 pgprot_writecombine
382 
383 /*
384  * Conversion functions: convert a page and protection to a page entry,
385  * and a page entry and page directory to the page they refer to.
386  *
387  * extern pte_t mk_pte(struct page *page, pgprot_t pgprot)
388  */
389 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
390 
391 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
392 {
393 	pte.pte_low &= _PAGE_CHG_MASK;
394 	pte.pte_low |= pgprot_val(newprot);
395 
396 #ifdef CONFIG_X2TLB
397 	pte.pte_high |= pgprot_val(newprot) >> 32;
398 #endif
399 
400 	return pte;
401 }
402 
403 static inline unsigned long pmd_page_vaddr(pmd_t pmd)
404 {
405 	return (unsigned long)pmd_val(pmd);
406 }
407 
408 #define pmd_pfn(pmd)		(__pa(pmd_val(pmd)) >> PAGE_SHIFT)
409 #define pmd_page(pmd)		(virt_to_page(pmd_val(pmd)))
410 
411 #ifdef CONFIG_X2TLB
412 #define pte_ERROR(e) \
413 	printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, \
414 	       &(e), (e).pte_high, (e).pte_low)
415 #define pgd_ERROR(e) \
416 	printk("%s:%d: bad pgd %016llx.\n", __FILE__, __LINE__, pgd_val(e))
417 #else
418 #define pte_ERROR(e) \
419 	printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
420 #define pgd_ERROR(e) \
421 	printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
422 #endif
423 
424 /*
425  * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
426  * are !pte_none() && !pte_present().
427  *
428  * Constraints:
429  *	_PAGE_PRESENT at bit 8
430  *	_PAGE_PROTNONE at bit 9
431  *
432  * For the normal case, we encode the swap type and offset into the swap PTE
433  * such that bits 8 and 9 stay zero. For the 64-bit PTE case, we use the
434  * upper 32 for the swap offset and swap type, following the same approach as
435  * x86 PAE. This keeps the logic quite simple.
436  *
437  * As is evident by the Alpha code, if we ever get a 64-bit unsigned
438  * long (swp_entry_t) to match up with the 64-bit PTEs, this all becomes
439  * much cleaner..
440  */
441 
442 #ifdef CONFIG_X2TLB
443 /*
444  * Format of swap PTEs:
445  *
446  *   6 6 6 6 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3
447  *   3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2
448  *   <--------------------- offset ----------------------> < type ->
449  *
450  *   3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
451  *   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
452  *   <------------------- zeroes --------------------> E 0 0 0 0 0 0
453  */
454 #define __swp_type(x)			((x).val & 0x1f)
455 #define __swp_offset(x)			((x).val >> 5)
456 #define __swp_entry(type, offset)	((swp_entry_t){ ((type) & 0x1f) | (offset) << 5})
457 #define __pte_to_swp_entry(pte)		((swp_entry_t){ (pte).pte_high })
458 #define __swp_entry_to_pte(x)		((pte_t){ 0, (x).val })
459 
460 #else
461 /*
462  * Format of swap PTEs:
463  *
464  *   3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
465  *   1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
466  *   <--------------- offset ----------------> 0 0 0 0 E < type -> 0
467  *
468  *   E is the exclusive marker that is not stored in swap entries.
469  */
470 #define __swp_type(x)			((x).val & 0x1f)
471 #define __swp_offset(x)			((x).val >> 10)
472 #define __swp_entry(type, offset)	((swp_entry_t){((type) & 0x1f) | (offset) << 10})
473 
474 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 1 })
475 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 1 })
476 #endif
477 
478 /* In both cases, we borrow bit 6 to store the exclusive marker in swap PTEs. */
479 #define _PAGE_SWP_EXCLUSIVE	_PAGE_USER
480 
481 static inline int pte_swp_exclusive(pte_t pte)
482 {
483 	return pte.pte_low & _PAGE_SWP_EXCLUSIVE;
484 }
485 
486 PTE_BIT_FUNC(low, swp_mkexclusive, |= _PAGE_SWP_EXCLUSIVE);
487 PTE_BIT_FUNC(low, swp_clear_exclusive, &= ~_PAGE_SWP_EXCLUSIVE);
488 
489 #endif /* __ASSEMBLY__ */
490 #endif /* __ASM_SH_PGTABLE_32_H */
491