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
);
64 static void cache_flush_page(void *adr
)
67 for (i
= 0; i
< PAGE_SIZE
; i
+= boot_cpu_data
.x86_clflush_size
)
68 asm volatile("clflush (%0)" :: "r" (adr
+ i
));
71 static void flush_kernel_map(void *arg
)
73 struct list_head
*l
= (struct list_head
*)arg
;
76 /* When clflush is available always use it because it is
77 much cheaper than WBINVD */
79 asm volatile("wbinvd" ::: "memory");
80 list_for_each_entry(pg
, l
, lru
) {
81 void *adr
= page_address(pg
);
83 cache_flush_page(adr
);
88 static inline void flush_map(struct list_head
*l
)
90 on_each_cpu(flush_kernel_map
, l
, 1, 1);
93 static LIST_HEAD(deferred_pages
); /* protected by init_mm.mmap_sem */
95 static inline void save_page(struct page
*fpage
)
97 list_add(&fpage
->lru
, &deferred_pages
);
101 * No more special protections in this 2/4MB area - revert to a
104 static void revert_page(unsigned long address
, pgprot_t ref_prot
)
112 pgd
= pgd_offset_k(address
);
113 BUG_ON(pgd_none(*pgd
));
114 pud
= pud_offset(pgd
,address
);
115 BUG_ON(pud_none(*pud
));
116 pmd
= pmd_offset(pud
, address
);
117 BUG_ON(pmd_val(*pmd
) & _PAGE_PSE
);
118 pfn
= (__pa(address
) & LARGE_PAGE_MASK
) >> PAGE_SHIFT
;
119 large_pte
= pfn_pte(pfn
, ref_prot
);
120 large_pte
= pte_mkhuge(large_pte
);
121 set_pte((pte_t
*)pmd
, large_pte
);
125 __change_page_attr(unsigned long address
, unsigned long pfn
, pgprot_t prot
,
129 struct page
*kpte_page
;
131 kpte
= lookup_address(address
);
133 kpte_page
= virt_to_page(((unsigned long)kpte
) & PAGE_MASK
);
134 if (pgprot_val(prot
) != pgprot_val(ref_prot
)) {
135 if (!pte_huge(*kpte
)) {
136 set_pte(kpte
, pfn_pte(pfn
, prot
));
139 * split_large_page will take the reference for this
140 * change_page_attr on the split page.
143 ref_prot2
= pte_pgprot(pte_clrhuge(*kpte
));
144 split
= split_large_page(address
, prot
, ref_prot2
);
147 set_pte(kpte
, mk_pte(split
, ref_prot2
));
150 page_private(kpte_page
)++;
151 } else if (!pte_huge(*kpte
)) {
152 set_pte(kpte
, pfn_pte(pfn
, ref_prot
));
153 BUG_ON(page_private(kpte_page
) == 0);
154 page_private(kpte_page
)--;
158 /* on x86-64 the direct mapping set at boot is not using 4k pages */
159 BUG_ON(PageReserved(kpte_page
));
161 if (page_private(kpte_page
) == 0) {
162 save_page(kpte_page
);
163 revert_page(address
, ref_prot
);
169 * Change the page attributes of an page in the linear mapping.
171 * This should be used when a page is mapped with a different caching policy
172 * than write-back somewhere - some CPUs do not like it when mappings with
173 * different caching policies exist. This changes the page attributes of the
174 * in kernel linear mapping too.
176 * The caller needs to ensure that there are no conflicting mappings elsewhere.
177 * This function only deals with the kernel linear map.
179 * Caller must call global_flush_tlb() after this.
181 int change_page_attr_addr(unsigned long address
, int numpages
, pgprot_t prot
)
183 int err
= 0, kernel_map
= 0;
186 if (address
>= __START_KERNEL_map
187 && address
< __START_KERNEL_map
+ KERNEL_TEXT_SIZE
) {
188 address
= (unsigned long)__va(__pa(address
));
192 down_write(&init_mm
.mmap_sem
);
193 for (i
= 0; i
< numpages
; i
++, address
+= PAGE_SIZE
) {
194 unsigned long pfn
= __pa(address
) >> PAGE_SHIFT
;
196 if (!kernel_map
|| pte_present(pfn_pte(0, prot
))) {
197 err
= __change_page_attr(address
, pfn
, prot
, PAGE_KERNEL
);
201 /* Handle kernel mapping too which aliases part of the
203 if (__pa(address
) < KERNEL_TEXT_SIZE
) {
206 addr2
= __START_KERNEL_map
+ __pa(address
);
207 /* Make sure the kernel mappings stay executable */
208 prot2
= pte_pgprot(pte_mkexec(pfn_pte(0, prot
)));
209 err
= __change_page_attr(addr2
, pfn
, prot2
,
213 up_write(&init_mm
.mmap_sem
);
217 /* Don't call this for MMIO areas that may not have a mem_map entry */
218 int change_page_attr(struct page
*page
, int numpages
, pgprot_t prot
)
220 unsigned long addr
= (unsigned long)page_address(page
);
221 return change_page_attr_addr(addr
, numpages
, prot
);
224 void global_flush_tlb(void)
226 struct page
*pg
, *next
;
229 down_read(&init_mm
.mmap_sem
);
230 list_replace_init(&deferred_pages
, &l
);
231 up_read(&init_mm
.mmap_sem
);
235 list_for_each_entry_safe(pg
, next
, &l
, lru
) {
236 ClearPagePrivate(pg
);
241 EXPORT_SYMBOL(change_page_attr
);
242 EXPORT_SYMBOL(global_flush_tlb
);