1 #ifndef __X86_PAGE_H__
2 #define __X86_PAGE_H__
3 
4 #include <xen/const.h>
5 #include <xen/page-size.h>
6 
7 #define PAGE_ORDER_4K       0
8 #define PAGE_ORDER_2M       9
9 #define PAGE_ORDER_1G       18
10 
11 #ifndef __ASSEMBLY__
12 # include <xen/types.h>
13 # include <xen/lib.h>
14 #endif
15 
16 #include <asm/x86_64/page.h>
17 
18 /* Read a pte atomically from memory. */
19 #define l1e_read_atomic(l1ep) \
20     l1e_from_intpte(pte_read_atomic(&l1e_get_intpte(*(l1ep))))
21 #define l2e_read_atomic(l2ep) \
22     l2e_from_intpte(pte_read_atomic(&l2e_get_intpte(*(l2ep))))
23 #define l3e_read_atomic(l3ep) \
24     l3e_from_intpte(pte_read_atomic(&l3e_get_intpte(*(l3ep))))
25 #define l4e_read_atomic(l4ep) \
26     l4e_from_intpte(pte_read_atomic(&l4e_get_intpte(*(l4ep))))
27 
28 /* Write a pte atomically to memory. */
29 #define l1e_write_atomic(l1ep, l1e) \
30     pte_write_atomic(&l1e_get_intpte(*(l1ep)), l1e_get_intpte(l1e))
31 #define l2e_write_atomic(l2ep, l2e) \
32     pte_write_atomic(&l2e_get_intpte(*(l2ep)), l2e_get_intpte(l2e))
33 #define l3e_write_atomic(l3ep, l3e) \
34     pte_write_atomic(&l3e_get_intpte(*(l3ep)), l3e_get_intpte(l3e))
35 #define l4e_write_atomic(l4ep, l4e) \
36     pte_write_atomic(&l4e_get_intpte(*(l4ep)), l4e_get_intpte(l4e))
37 
38 /*
39  * Write a pte safely but non-atomically to memory.
40  * The PTE may become temporarily not-present during the update.
41  */
42 #define l1e_write(l1ep, l1e) \
43     pte_write(&l1e_get_intpte(*(l1ep)), l1e_get_intpte(l1e))
44 #define l2e_write(l2ep, l2e) \
45     pte_write(&l2e_get_intpte(*(l2ep)), l2e_get_intpte(l2e))
46 #define l3e_write(l3ep, l3e) \
47     pte_write(&l3e_get_intpte(*(l3ep)), l3e_get_intpte(l3e))
48 #define l4e_write(l4ep, l4e) \
49     pte_write(&l4e_get_intpte(*(l4ep)), l4e_get_intpte(l4e))
50 
51 /* Get direct integer representation of a pte's contents (intpte_t). */
52 #define l1e_get_intpte(x)          ((x).l1)
53 #define l2e_get_intpte(x)          ((x).l2)
54 #define l3e_get_intpte(x)          ((x).l3)
55 #define l4e_get_intpte(x)          ((x).l4)
56 
57 /* Get pfn mapped by pte (unsigned long). */
58 #define l1e_get_pfn(x)             \
59     ((unsigned long)(((x).l1 & (PADDR_MASK&PAGE_MASK)) >> PAGE_SHIFT))
60 #define l2e_get_pfn(x)             \
61     ((unsigned long)(((x).l2 & (PADDR_MASK&PAGE_MASK)) >> PAGE_SHIFT))
62 #define l3e_get_pfn(x)             \
63     ((unsigned long)(((x).l3 & (PADDR_MASK&PAGE_MASK)) >> PAGE_SHIFT))
64 #define l4e_get_pfn(x)             \
65     ((unsigned long)(((x).l4 & (PADDR_MASK&PAGE_MASK)) >> PAGE_SHIFT))
66 
67 /* Get mfn mapped by pte (mfn_t). */
68 #define l1e_get_mfn(x) _mfn(l1e_get_pfn(x))
69 #define l2e_get_mfn(x) _mfn(l2e_get_pfn(x))
70 #define l3e_get_mfn(x) _mfn(l3e_get_pfn(x))
71 #define l4e_get_mfn(x) _mfn(l4e_get_pfn(x))
72 
73 /* Get physical address of page mapped by pte (paddr_t). */
74 #define l1e_get_paddr(x)           \
75     ((paddr_t)(((x).l1 & (PADDR_MASK&PAGE_MASK))))
76 #define l2e_get_paddr(x)           \
77     ((paddr_t)(((x).l2 & (PADDR_MASK&PAGE_MASK))))
78 #define l3e_get_paddr(x)           \
79     ((paddr_t)(((x).l3 & (PADDR_MASK&PAGE_MASK))))
80 #define l4e_get_paddr(x)           \
81     ((paddr_t)(((x).l4 & (PADDR_MASK&PAGE_MASK))))
82 
83 /* Get pointer to info structure of page mapped by pte (struct page_info *). */
84 #define l1e_get_page(x)           mfn_to_page(l1e_get_mfn(x))
85 #define l2e_get_page(x)           mfn_to_page(l2e_get_mfn(x))
86 #define l3e_get_page(x)           mfn_to_page(l3e_get_mfn(x))
87 #define l4e_get_page(x)           mfn_to_page(l4e_get_mfn(x))
88 
89 /* Get pte access flags (unsigned int). */
90 #define l1e_get_flags(x)           (get_pte_flags((x).l1))
91 #define l2e_get_flags(x)           (get_pte_flags((x).l2))
92 #define l3e_get_flags(x)           (get_pte_flags((x).l3))
93 #define l4e_get_flags(x)           (get_pte_flags((x).l4))
94 
95 /* Get pte pkeys (unsigned int). */
96 #define l1e_get_pkey(x)           get_pte_pkey((x).l1)
97 #define l2e_get_pkey(x)           get_pte_pkey((x).l2)
98 #define l3e_get_pkey(x)           get_pte_pkey((x).l3)
99 
100 /* Construct an empty pte. */
101 #define l1e_empty()                ((l1_pgentry_t) { 0 })
102 #define l2e_empty()                ((l2_pgentry_t) { 0 })
103 #define l3e_empty()                ((l3_pgentry_t) { 0 })
104 #define l4e_empty()                ((l4_pgentry_t) { 0 })
105 
106 /* Construct a pte from a pfn and access flags. */
107 #define l1e_from_pfn(pfn, flags)   \
108     ((l1_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) })
109 #define l2e_from_pfn(pfn, flags)   \
110     ((l2_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) })
111 #define l3e_from_pfn(pfn, flags)   \
112     ((l3_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) })
113 #define l4e_from_pfn(pfn, flags)   \
114     ((l4_pgentry_t) { ((intpte_t)(pfn) << PAGE_SHIFT) | put_pte_flags(flags) })
115 
116 /* Construct a pte from an mfn and access flags. */
117 #define l1e_from_mfn(m, f) l1e_from_pfn(mfn_x(m), f)
118 #define l2e_from_mfn(m, f) l2e_from_pfn(mfn_x(m), f)
119 #define l3e_from_mfn(m, f) l3e_from_pfn(mfn_x(m), f)
120 #define l4e_from_mfn(m, f) l4e_from_pfn(mfn_x(m), f)
121 
122 /* Construct a pte from a physical address and access flags. */
123 #ifndef __ASSEMBLY__
l1e_from_paddr(paddr_t pa,unsigned int flags)124 static inline l1_pgentry_t l1e_from_paddr(paddr_t pa, unsigned int flags)
125 {
126     ASSERT((pa & ~(PADDR_MASK & PAGE_MASK)) == 0);
127     return (l1_pgentry_t) { pa | put_pte_flags(flags) };
128 }
l2e_from_paddr(paddr_t pa,unsigned int flags)129 static inline l2_pgentry_t l2e_from_paddr(paddr_t pa, unsigned int flags)
130 {
131     ASSERT((pa & ~(PADDR_MASK & PAGE_MASK)) == 0);
132     return (l2_pgentry_t) { pa | put_pte_flags(flags) };
133 }
l3e_from_paddr(paddr_t pa,unsigned int flags)134 static inline l3_pgentry_t l3e_from_paddr(paddr_t pa, unsigned int flags)
135 {
136     ASSERT((pa & ~(PADDR_MASK & PAGE_MASK)) == 0);
137     return (l3_pgentry_t) { pa | put_pte_flags(flags) };
138 }
l4e_from_paddr(paddr_t pa,unsigned int flags)139 static inline l4_pgentry_t l4e_from_paddr(paddr_t pa, unsigned int flags)
140 {
141     ASSERT((pa & ~(PADDR_MASK & PAGE_MASK)) == 0);
142     return (l4_pgentry_t) { pa | put_pte_flags(flags) };
143 }
144 #endif /* !__ASSEMBLY__ */
145 
146 /* Construct a pte from its direct integer representation. */
147 #define l1e_from_intpte(intpte)    ((l1_pgentry_t) { (intpte_t)(intpte) })
148 #define l2e_from_intpte(intpte)    ((l2_pgentry_t) { (intpte_t)(intpte) })
149 #define l3e_from_intpte(intpte)    ((l3_pgentry_t) { (intpte_t)(intpte) })
150 #define l4e_from_intpte(intpte)    ((l4_pgentry_t) { (intpte_t)(intpte) })
151 
152 /* Construct a pte from a page pointer and access flags. */
153 #define l1e_from_page(page, flags) l1e_from_mfn(page_to_mfn(page), flags)
154 #define l2e_from_page(page, flags) l2e_from_mfn(page_to_mfn(page), flags)
155 #define l3e_from_page(page, flags) l3e_from_mfn(page_to_mfn(page), flags)
156 #define l4e_from_page(page, flags) l4e_from_mfn(page_to_mfn(page), flags)
157 
158 /* Add extra flags to an existing pte. */
159 #define l1e_add_flags(x, flags)    ((x).l1 |= put_pte_flags(flags))
160 #define l2e_add_flags(x, flags)    ((x).l2 |= put_pte_flags(flags))
161 #define l3e_add_flags(x, flags)    ((x).l3 |= put_pte_flags(flags))
162 #define l4e_add_flags(x, flags)    ((x).l4 |= put_pte_flags(flags))
163 
164 /* Remove flags from an existing pte. */
165 #define l1e_remove_flags(x, flags) ((x).l1 &= ~put_pte_flags(flags))
166 #define l2e_remove_flags(x, flags) ((x).l2 &= ~put_pte_flags(flags))
167 #define l3e_remove_flags(x, flags) ((x).l3 &= ~put_pte_flags(flags))
168 #define l4e_remove_flags(x, flags) ((x).l4 &= ~put_pte_flags(flags))
169 
170 /* Flip flags in an existing L1 PTE. */
171 #define l1e_flip_flags(x, flags)    ((x).l1 ^= put_pte_flags(flags))
172 
173 /* Check if a pte's page mapping or significant access flags have changed. */
174 #define l1e_has_changed(x,y,flags) \
175     ( !!(((x).l1 ^ (y).l1) & ((PADDR_MASK&PAGE_MASK)|put_pte_flags(flags))) )
176 #define l2e_has_changed(x,y,flags) \
177     ( !!(((x).l2 ^ (y).l2) & ((PADDR_MASK&PAGE_MASK)|put_pte_flags(flags))) )
178 #define l3e_has_changed(x,y,flags) \
179     ( !!(((x).l3 ^ (y).l3) & ((PADDR_MASK&PAGE_MASK)|put_pte_flags(flags))) )
180 #define l4e_has_changed(x,y,flags) \
181     ( !!(((x).l4 ^ (y).l4) & ((PADDR_MASK&PAGE_MASK)|put_pte_flags(flags))) )
182 
183 #define map_l1t_from_l2e(x)        (l1_pgentry_t *)map_domain_page(l2e_get_mfn(x))
184 #define map_l2t_from_l3e(x)        (l2_pgentry_t *)map_domain_page(l3e_get_mfn(x))
185 #define map_l3t_from_l4e(x)        (l3_pgentry_t *)map_domain_page(l4e_get_mfn(x))
186 
187 /* Unlike lYe_to_lXe(), lXe_from_lYe() do not rely on the direct map. */
188 #define l1e_from_l2e(l2e_, offset_) ({                      \
189         const l1_pgentry_t *l1t_ = map_l1t_from_l2e(l2e_);  \
190         l1_pgentry_t l1e_ = l1t_[offset_];                  \
191         unmap_domain_page(l1t_);                            \
192         l1e_; })
193 
194 #define l2e_from_l3e(l3e_, offset_) ({                      \
195         const l2_pgentry_t *l2t_ = map_l2t_from_l3e(l3e_);  \
196         l2_pgentry_t l2e_ = l2t_[offset_];                  \
197         unmap_domain_page(l2t_);                            \
198         l2e_; })
199 
200 #define l3e_from_l4e(l4e_, offset_) ({                      \
201         const l3_pgentry_t *l3t_ = map_l3t_from_l4e(l4e_);  \
202         l3_pgentry_t l3e_ = l3t_[offset_];                  \
203         unmap_domain_page(l3t_);                            \
204         l3e_; })
205 
206 /* Given a virtual address, get an entry offset into a page table. */
207 #define l1_table_offset(a)         \
208     (((a) >> L1_PAGETABLE_SHIFT) & (L1_PAGETABLE_ENTRIES - 1))
209 #define l2_table_offset(a)         \
210     (((a) >> L2_PAGETABLE_SHIFT) & (L2_PAGETABLE_ENTRIES - 1))
211 #define l3_table_offset(a)         \
212     (((a) >> L3_PAGETABLE_SHIFT) & (L3_PAGETABLE_ENTRIES - 1))
213 #define l4_table_offset(a)         \
214     (((a) >> L4_PAGETABLE_SHIFT) & (L4_PAGETABLE_ENTRIES - 1))
215 
216 /* Convert a pointer to a page-table entry into pagetable slot index. */
217 #define pgentry_ptr_to_slot(_p)    \
218     (((unsigned long)(_p) & ~PAGE_MASK) / sizeof(*(_p)))
219 
220 #ifndef __ASSEMBLY__
221 
222 /* Page-table type. */
223 typedef struct { u64 pfn; } pagetable_t;
224 #define pagetable_get_paddr(x)  ((paddr_t)(x).pfn << PAGE_SHIFT)
225 #define pagetable_get_page(x)   mfn_to_page(pagetable_get_mfn(x))
226 #define pagetable_get_pfn(x)    ((x).pfn)
227 #define pagetable_get_mfn(x)    _mfn(((x).pfn))
228 #define pagetable_is_null(x)    ((x).pfn == 0)
229 #define pagetable_from_pfn(pfn) ((pagetable_t) { (pfn) })
230 #define pagetable_from_mfn(mfn) ((pagetable_t) { mfn_x(mfn) })
231 #define pagetable_from_page(pg) pagetable_from_mfn(page_to_mfn(pg))
232 #define pagetable_from_paddr(p) pagetable_from_pfn((p)>>PAGE_SHIFT)
233 #define pagetable_null()        pagetable_from_pfn(0)
234 
235 void clear_page_sse2(void *pg);
236 void copy_page_sse2(void *to, const void *from);
237 
238 #define clear_page(_p)      clear_page_sse2(_p)
239 #define copy_page(_t, _f)   copy_page_sse2(_t, _f)
240 
241 /* Convert between Xen-heap virtual addresses and machine addresses. */
242 #define __pa(x)             (virt_to_maddr(x))
243 #define __va(x)             (maddr_to_virt(x))
244 
245 /* Convert between Xen-heap virtual addresses and machine frame numbers. */
246 #define __virt_to_mfn(va)   (virt_to_maddr(va) >> PAGE_SHIFT)
247 #define __mfn_to_virt(mfn)  (maddr_to_virt((paddr_t)(mfn) << PAGE_SHIFT))
248 
249 /* Convert between machine frame numbers and page-info structures. */
250 #define mfn_to_page(mfn)    (frame_table + mfn_to_pdx(mfn))
251 #define page_to_mfn(pg)     pdx_to_mfn((unsigned long)((pg) - frame_table))
252 
253 /* Convert between machine addresses and page-info structures. */
254 #define __maddr_to_page(ma) mfn_to_page(maddr_to_mfn(ma))
255 #define __page_to_maddr(pg) mfn_to_maddr(page_to_mfn(pg))
256 
257 /* Convert between frame number and address formats.  */
258 #define __pfn_to_paddr(pfn) ((paddr_t)(pfn) << PAGE_SHIFT)
259 #define __paddr_to_pfn(pa)  ((unsigned long)((pa) >> PAGE_SHIFT))
260 #define gfn_to_gaddr(gfn)   __pfn_to_paddr(gfn_x(gfn))
261 #define gaddr_to_gfn(ga)    _gfn(__paddr_to_pfn(ga))
262 #define mfn_to_maddr(mfn)   __pfn_to_paddr(mfn_x(mfn))
263 #define maddr_to_mfn(ma)    _mfn(__paddr_to_pfn(ma))
264 
265 /*
266  * We define non-underscored wrappers for above conversion functions. These are
267  * overridden in various source files while underscored versions remain intact.
268  */
269 #define mfn_valid(mfn)      __mfn_valid(mfn_x(mfn))
270 #define virt_to_mfn(va)     __virt_to_mfn(va)
271 #define mfn_to_virt(mfn)    __mfn_to_virt(mfn)
272 #define virt_to_maddr(va)   __virt_to_maddr((unsigned long)(va))
273 #define maddr_to_virt(ma)   __maddr_to_virt((unsigned long)(ma))
274 #define maddr_to_page(ma)   __maddr_to_page(ma)
275 #define page_to_maddr(pg)   __page_to_maddr(pg)
276 #define virt_to_page(va)    __virt_to_page(va)
277 #define page_to_virt(pg)    __page_to_virt(pg)
278 #define pfn_to_paddr(pfn)   __pfn_to_paddr(pfn)
279 #define paddr_to_pfn(pa)    __paddr_to_pfn(pa)
280 #define paddr_to_pdx(pa)    pfn_to_pdx(paddr_to_pfn(pa))
281 #define vmap_to_mfn(va)     xen_map_to_mfn((unsigned long)(va))
282 #define vmap_to_page(va)    mfn_to_page(vmap_to_mfn(va))
283 
284 #endif /* !defined(__ASSEMBLY__) */
285 
286 /* Where to find each level of the linear mapping */
287 #define __linear_l1_table ((l1_pgentry_t *)(LINEAR_PT_VIRT_START))
288 #define __linear_l2_table \
289  ((l2_pgentry_t *)(__linear_l1_table + l1_linear_offset(LINEAR_PT_VIRT_START)))
290 #define __linear_l3_table \
291  ((l3_pgentry_t *)(__linear_l2_table + l2_linear_offset(LINEAR_PT_VIRT_START)))
292 #define __linear_l4_table \
293  ((l4_pgentry_t *)(__linear_l3_table + l3_linear_offset(LINEAR_PT_VIRT_START)))
294 
295 
296 #ifndef __ASSEMBLY__
297 extern root_pgentry_t idle_pg_table[ROOT_PAGETABLE_ENTRIES];
298 extern l2_pgentry_t  *compat_idle_pg_table_l2;
299 extern unsigned int   m2p_compat_vstart;
300 extern l2_pgentry_t l2_xenmap[L2_PAGETABLE_ENTRIES],
301     l2_bootmap[4*L2_PAGETABLE_ENTRIES];
302 extern l3_pgentry_t l3_bootmap[L3_PAGETABLE_ENTRIES];
303 extern l2_pgentry_t l2_directmap[4*L2_PAGETABLE_ENTRIES];
304 extern l1_pgentry_t l1_fixmap[L1_PAGETABLE_ENTRIES];
305 void paging_init(void);
306 void efi_update_l4_pgtable(unsigned int l4idx, l4_pgentry_t l4e);
307 #endif /* !defined(__ASSEMBLY__) */
308 
309 #define _PAGE_NONE     _AC(0x000,U)
310 #define _PAGE_PRESENT  _AC(0x001,U)
311 #define _PAGE_RW       _AC(0x002,U)
312 #define _PAGE_USER     _AC(0x004,U)
313 #define _PAGE_PWT      _AC(0x008,U)
314 #define _PAGE_PCD      _AC(0x010,U)
315 #define _PAGE_ACCESSED _AC(0x020,U)
316 #define _PAGE_DIRTY    _AC(0x040,U)
317 #define _PAGE_PAT      _AC(0x080,U)
318 #define _PAGE_PSE      _AC(0x080,U)
319 #define _PAGE_GLOBAL   _AC(0x100,U)
320 #define _PAGE_AVAIL0   _AC(0x200,U)
321 #define _PAGE_AVAIL1   _AC(0x400,U)
322 #define _PAGE_AVAIL2   _AC(0x800,U)
323 #define _PAGE_AVAIL    _AC(0xE00,U)
324 #define _PAGE_PSE_PAT  _AC(0x1000,U)
325 #define _PAGE_AVAIL_HIGH (_AC(0x7ff, U) << 12)
326 
327 #ifndef __ASSEMBLY__
328 /* Dependency on NX being available can't be expressed. */
329 #define _PAGE_NX       (cpu_has_nx ? _PAGE_NX_BIT : 0)
330 #endif
331 
332 #define PAGE_CACHE_ATTRS (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)
333 
334 /* Memory types, encoded under Xen's choice of MSR_PAT. */
335 #define _PAGE_WB         (                                0)
336 #define _PAGE_WT         (                        _PAGE_PWT)
337 #define _PAGE_UCM        (            _PAGE_PCD            )
338 #define _PAGE_UC         (            _PAGE_PCD | _PAGE_PWT)
339 #define _PAGE_WC         (_PAGE_PAT                        )
340 #define _PAGE_WP         (_PAGE_PAT |             _PAGE_PWT)
341 
342 /*
343  * Debug option: Ensure that granted mappings are not implicitly unmapped.
344  * WARNING: This will need to be disabled to run OSes that use the spare PTE
345  * bits themselves (e.g., *BSD).
346  */
347 #ifdef NDEBUG
348 #undef _PAGE_GNTTAB
349 #endif
350 #ifndef _PAGE_GNTTAB
351 #define _PAGE_GNTTAB   0
352 #endif
353 
354 #define __PAGE_HYPERVISOR_RO      (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_NX)
355 #define __PAGE_HYPERVISOR_RW      (__PAGE_HYPERVISOR_RO | \
356                                    _PAGE_DIRTY | _PAGE_RW)
357 #define __PAGE_HYPERVISOR_RX      (_PAGE_PRESENT | _PAGE_ACCESSED)
358 #define __PAGE_HYPERVISOR         (__PAGE_HYPERVISOR_RX | \
359                                    _PAGE_DIRTY | _PAGE_RW)
360 #define __PAGE_HYPERVISOR_WT      (__PAGE_HYPERVISOR | _PAGE_WT)
361 #define __PAGE_HYPERVISOR_UCMINUS (__PAGE_HYPERVISOR | _PAGE_UCM)
362 #define __PAGE_HYPERVISOR_UC      (__PAGE_HYPERVISOR | _PAGE_UC)
363 #define __PAGE_HYPERVISOR_WC      (__PAGE_HYPERVISOR | _PAGE_WC)
364 #define __PAGE_HYPERVISOR_SHSTK   (__PAGE_HYPERVISOR_RO | _PAGE_DIRTY)
365 
366 #define MAP_SMALL_PAGES _PAGE_AVAIL0 /* don't use superpages mappings */
367 
368 #ifndef __ASSEMBLY__
369 
370 /* Convert between PAT/PCD/PWT embedded in PTE flags and 3-bit cacheattr. */
pte_flags_to_cacheattr(unsigned int flags)371 static inline unsigned int pte_flags_to_cacheattr(unsigned int flags)
372 {
373     return ((flags >> 5) & 4) | ((flags >> 3) & 3);
374 }
cacheattr_to_pte_flags(unsigned int cacheattr)375 static inline unsigned int cacheattr_to_pte_flags(unsigned int cacheattr)
376 {
377     return ((cacheattr & 4) << 5) | ((cacheattr & 3) << 3);
378 }
379 
380 /* return true if permission increased */
381 static inline bool
perms_strictly_increased(uint32_t old_flags,uint32_t new_flags)382 perms_strictly_increased(uint32_t old_flags, uint32_t new_flags)
383 /* Given the flags of two entries, are the new flags a strict
384  * increase in rights over the old ones? */
385 {
386     uint32_t of = old_flags & (_PAGE_PRESENT|_PAGE_RW|_PAGE_USER|_PAGE_NX_BIT);
387     uint32_t nf = new_flags & (_PAGE_PRESENT|_PAGE_RW|_PAGE_USER|_PAGE_NX_BIT);
388     /* Flip the NX bit, since it's the only one that decreases rights;
389      * we calculate as if it were an "X" bit. */
390     of ^= _PAGE_NX_BIT;
391     nf ^= _PAGE_NX_BIT;
392     /* If the changed bits are all set in the new flags, then rights strictly
393      * increased between old and new. */
394     return ((of | (of ^ nf)) == nf);
395 }
396 
invalidate_icache(void)397 static inline void invalidate_icache(void)
398 {
399 /*
400  * There is nothing to be done here as icaches are sufficiently
401  * coherent on x86.
402  */
403 }
404 
405 #endif /* !__ASSEMBLY__ */
406 
407 #endif /* __X86_PAGE_H__ */
408 
409 /*
410  * Local variables:
411  * mode: C
412  * c-file-style: "BSD"
413  * c-basic-offset: 4
414  * tab-width: 4
415  * indent-tabs-mode: nil
416  * End:
417  */
418