2 * Copyright 2002 Andi Kleen, SuSE Labs.
3 * Thanks to Ben LaHaise for precious feedback.
7 #include <linux/sched.h>
8 #include <linux/highmem.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <asm/uaccess.h>
12 #include <asm/processor.h>
13 #include <asm/tlbflush.h>
16 static inline pte_t
*lookup_address(unsigned long address
)
18 pgd_t
*pgd
= pgd_offset_k(address
);
24 pud
= pud_offset(pgd
, address
);
25 if (!pud_present(*pud
))
27 pmd
= pmd_offset(pud
, address
);
28 if (!pmd_present(*pmd
))
32 pte
= pte_offset_kernel(pmd
, address
);
33 if (pte
&& !pte_present(*pte
))
38 static struct page
*split_large_page(unsigned long address
, pgprot_t prot
,
43 struct page
*base
= alloc_pages(GFP_KERNEL
, 0);
48 * page_private is used to track the number of entries in
49 * the page table page have non standard attributes.
52 page_private(base
) = 0;
54 address
= __pa(address
);
55 addr
= address
& LARGE_PAGE_MASK
;
56 pbase
= (pte_t
*)page_address(base
);
57 for (i
= 0; i
< PTRS_PER_PTE
; i
++, addr
+= PAGE_SIZE
) {
58 pbase
[i
] = pfn_pte(addr
>> PAGE_SHIFT
,
59 addr
== address
? prot
: ref_prot
);
65 static void flush_kernel_map(void *address
)
67 if (0 && address
&& cpu_has_clflush
) {
68 /* is this worth it? */
70 for (i
= 0; i
< PAGE_SIZE
; i
+= boot_cpu_data
.x86_clflush_size
)
71 asm volatile("clflush (%0)" :: "r" (address
+ i
));
73 asm volatile("wbinvd":::"memory");
75 __flush_tlb_one(address
);
81 static inline void flush_map(unsigned long address
)
83 on_each_cpu(flush_kernel_map
, (void *)address
, 1, 1);
86 static struct page
*deferred_pages
; /* protected by init_mm.mmap_sem */
88 static inline void save_page(struct page
*fpage
)
90 fpage
->lru
.next
= (struct list_head
*)deferred_pages
;
91 deferred_pages
= fpage
;
95 * No more special protections in this 2/4MB area - revert to a
98 static void revert_page(unsigned long address
, pgprot_t ref_prot
)
105 pgd
= pgd_offset_k(address
);
106 BUG_ON(pgd_none(*pgd
));
107 pud
= pud_offset(pgd
,address
);
108 BUG_ON(pud_none(*pud
));
109 pmd
= pmd_offset(pud
, address
);
110 BUG_ON(pmd_val(*pmd
) & _PAGE_PSE
);
111 pgprot_val(ref_prot
) |= _PAGE_PSE
;
112 large_pte
= mk_pte_phys(__pa(address
) & LARGE_PAGE_MASK
, ref_prot
);
113 set_pte((pte_t
*)pmd
, large_pte
);
117 __change_page_attr(unsigned long address
, unsigned long pfn
, pgprot_t prot
,
121 struct page
*kpte_page
;
124 kpte
= lookup_address(address
);
126 kpte_page
= virt_to_page(((unsigned long)kpte
) & PAGE_MASK
);
127 kpte_flags
= pte_val(*kpte
);
128 if (pgprot_val(prot
) != pgprot_val(ref_prot
)) {
129 if ((kpte_flags
& _PAGE_PSE
) == 0) {
130 set_pte(kpte
, pfn_pte(pfn
, prot
));
133 * split_large_page will take the reference for this
134 * change_page_attr on the split page.
138 ref_prot2
= __pgprot(pgprot_val(pte_pgprot(*lookup_address(address
))) & ~(1<<_PAGE_BIT_PSE
));
140 split
= split_large_page(address
, prot
, ref_prot2
);
143 set_pte(kpte
,mk_pte(split
, ref_prot2
));
146 page_private(kpte_page
)++;
147 } else if ((kpte_flags
& _PAGE_PSE
) == 0) {
148 set_pte(kpte
, pfn_pte(pfn
, ref_prot
));
149 BUG_ON(page_private(kpte_page
) == 0);
150 page_private(kpte_page
)--;
154 /* on x86-64 the direct mapping set at boot is not using 4k pages */
155 BUG_ON(PageReserved(kpte_page
));
157 if (page_private(kpte_page
) == 0) {
158 save_page(kpte_page
);
159 revert_page(address
, ref_prot
);
165 * Change the page attributes of an page in the linear mapping.
167 * This should be used when a page is mapped with a different caching policy
168 * than write-back somewhere - some CPUs do not like it when mappings with
169 * different caching policies exist. This changes the page attributes of the
170 * in kernel linear mapping too.
172 * The caller needs to ensure that there are no conflicting mappings elsewhere.
173 * This function only deals with the kernel linear map.
175 * Caller must call global_flush_tlb() after this.
177 int change_page_attr_addr(unsigned long address
, int numpages
, pgprot_t prot
)
182 down_write(&init_mm
.mmap_sem
);
183 for (i
= 0; i
< numpages
; i
++, address
+= PAGE_SIZE
) {
184 unsigned long pfn
= __pa(address
) >> PAGE_SHIFT
;
186 err
= __change_page_attr(address
, pfn
, prot
, PAGE_KERNEL
);
189 /* Handle kernel mapping too which aliases part of the
191 if (__pa(address
) < KERNEL_TEXT_SIZE
) {
193 pgprot_t prot2
= prot
;
194 addr2
= __START_KERNEL_map
+ __pa(address
);
195 pgprot_val(prot2
) &= ~_PAGE_NX
;
196 err
= __change_page_attr(addr2
, pfn
, prot2
, PAGE_KERNEL_EXEC
);
199 up_write(&init_mm
.mmap_sem
);
203 /* Don't call this for MMIO areas that may not have a mem_map entry */
204 int change_page_attr(struct page
*page
, int numpages
, pgprot_t prot
)
206 unsigned long addr
= (unsigned long)page_address(page
);
207 return change_page_attr_addr(addr
, numpages
, prot
);
210 void global_flush_tlb(void)
214 down_read(&init_mm
.mmap_sem
);
215 dpage
= xchg(&deferred_pages
, NULL
);
216 up_read(&init_mm
.mmap_sem
);
218 flush_map((dpage
&& !dpage
->lru
.next
) ? (unsigned long)page_address(dpage
) : 0);
220 struct page
*tmp
= dpage
;
221 dpage
= (struct page
*)dpage
->lru
.next
;
222 ClearPagePrivate(tmp
);
227 EXPORT_SYMBOL(change_page_attr
);
228 EXPORT_SYMBOL(global_flush_tlb
);
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