Merge branch 'drm-patches' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied...
[linux-2.6] / arch / x86_64 / mm / pageattr.c
1 /* 
2  * Copyright 2002 Andi Kleen, SuSE Labs. 
3  * Thanks to Ben LaHaise for precious feedback.
4  */ 
5
6 #include <linux/config.h>
7 #include <linux/mm.h>
8 #include <linux/sched.h>
9 #include <linux/highmem.h>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <asm/uaccess.h>
13 #include <asm/processor.h>
14 #include <asm/tlbflush.h>
15 #include <asm/io.h>
16
17 static inline pte_t *lookup_address(unsigned long address) 
18
19         pgd_t *pgd = pgd_offset_k(address);
20         pud_t *pud;
21         pmd_t *pmd;
22         pte_t *pte;
23         if (pgd_none(*pgd))
24                 return NULL;
25         pud = pud_offset(pgd, address);
26         if (!pud_present(*pud))
27                 return NULL; 
28         pmd = pmd_offset(pud, address);
29         if (!pmd_present(*pmd))
30                 return NULL; 
31         if (pmd_large(*pmd))
32                 return (pte_t *)pmd;
33         pte = pte_offset_kernel(pmd, address);
34         if (pte && !pte_present(*pte))
35                 pte = NULL; 
36         return pte;
37
38
39 static struct page *split_large_page(unsigned long address, pgprot_t prot,
40                                      pgprot_t ref_prot)
41
42         int i; 
43         unsigned long addr;
44         struct page *base = alloc_pages(GFP_KERNEL, 0);
45         pte_t *pbase;
46         if (!base) 
47                 return NULL;
48         /*
49          * page_private is used to track the number of entries in
50          * the page table page have non standard attributes.
51          */
52         SetPagePrivate(base);
53         page_private(base) = 0;
54
55         address = __pa(address);
56         addr = address & LARGE_PAGE_MASK; 
57         pbase = (pte_t *)page_address(base);
58         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
59                 pbase[i] = pfn_pte(addr >> PAGE_SHIFT, 
60                                    addr == address ? prot : ref_prot);
61         }
62         return base;
63
64
65
66 static void flush_kernel_map(void *address) 
67 {
68         if (0 && address && cpu_has_clflush) {
69                 /* is this worth it? */ 
70                 int i;
71                 for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size) 
72                         asm volatile("clflush (%0)" :: "r" (address + i)); 
73         } else
74                 asm volatile("wbinvd":::"memory"); 
75         if (address)
76                 __flush_tlb_one(address);
77         else
78                 __flush_tlb_all();
79 }
80
81
82 static inline void flush_map(unsigned long address)
83 {       
84         on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
85 }
86
87 static struct page *deferred_pages; /* protected by init_mm.mmap_sem */
88
89 static inline void save_page(struct page *fpage)
90 {
91         fpage->lru.next = (struct list_head *)deferred_pages;
92         deferred_pages = fpage;
93 }
94
95 /* 
96  * No more special protections in this 2/4MB area - revert to a
97  * large page again. 
98  */
99 static void revert_page(unsigned long address, pgprot_t ref_prot)
100 {
101         pgd_t *pgd;
102         pud_t *pud;
103         pmd_t *pmd;
104         pte_t large_pte;
105
106         pgd = pgd_offset_k(address);
107         BUG_ON(pgd_none(*pgd));
108         pud = pud_offset(pgd,address);
109         BUG_ON(pud_none(*pud));
110         pmd = pmd_offset(pud, address);
111         BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
112         pgprot_val(ref_prot) |= _PAGE_PSE;
113         large_pte = mk_pte_phys(__pa(address) & LARGE_PAGE_MASK, ref_prot);
114         set_pte((pte_t *)pmd, large_pte);
115 }      
116
117 static int
118 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
119                                    pgprot_t ref_prot)
120
121         pte_t *kpte; 
122         struct page *kpte_page;
123         unsigned kpte_flags;
124         pgprot_t ref_prot2;
125         kpte = lookup_address(address);
126         if (!kpte) return 0;
127         kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
128         kpte_flags = pte_val(*kpte); 
129         if (pgprot_val(prot) != pgprot_val(ref_prot)) { 
130                 if ((kpte_flags & _PAGE_PSE) == 0) { 
131                         set_pte(kpte, pfn_pte(pfn, prot));
132                 } else {
133                         /*
134                          * split_large_page will take the reference for this
135                          * change_page_attr on the split page.
136                          */
137
138                         struct page *split;
139                         ref_prot2 = __pgprot(pgprot_val(pte_pgprot(*lookup_address(address))) & ~(1<<_PAGE_BIT_PSE));
140
141                         split = split_large_page(address, prot, ref_prot2);
142                         if (!split)
143                                 return -ENOMEM;
144                         set_pte(kpte,mk_pte(split, ref_prot2));
145                         kpte_page = split;
146                 }       
147                 page_private(kpte_page)++;
148         } else if ((kpte_flags & _PAGE_PSE) == 0) { 
149                 set_pte(kpte, pfn_pte(pfn, ref_prot));
150                 BUG_ON(page_private(kpte_page) == 0);
151                 page_private(kpte_page)--;
152         } else
153                 BUG();
154
155         /* on x86-64 the direct mapping set at boot is not using 4k pages */
156         BUG_ON(PageReserved(kpte_page));
157
158         if (page_private(kpte_page) == 0) {
159                 save_page(kpte_page);
160                 revert_page(address, ref_prot);
161         }
162         return 0;
163
164
165 /*
166  * Change the page attributes of an page in the linear mapping.
167  *
168  * This should be used when a page is mapped with a different caching policy
169  * than write-back somewhere - some CPUs do not like it when mappings with
170  * different caching policies exist. This changes the page attributes of the
171  * in kernel linear mapping too.
172  * 
173  * The caller needs to ensure that there are no conflicting mappings elsewhere.
174  * This function only deals with the kernel linear map.
175  * 
176  * Caller must call global_flush_tlb() after this.
177  */
178 int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
179 {
180         int err = 0; 
181         int i; 
182
183         down_write(&init_mm.mmap_sem);
184         for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
185                 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
186
187                 err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
188                 if (err) 
189                         break; 
190                 /* Handle kernel mapping too which aliases part of the
191                  * lowmem */
192                 if (__pa(address) < KERNEL_TEXT_SIZE) {
193                         unsigned long addr2;
194                         pgprot_t prot2 = prot;
195                         addr2 = __START_KERNEL_map + __pa(address);
196                         pgprot_val(prot2) &= ~_PAGE_NX;
197                         err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC);
198                 } 
199         }       
200         up_write(&init_mm.mmap_sem); 
201         return err;
202 }
203
204 /* Don't call this for MMIO areas that may not have a mem_map entry */
205 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
206 {
207         unsigned long addr = (unsigned long)page_address(page);
208         return change_page_attr_addr(addr, numpages, prot);
209 }
210
211 void global_flush_tlb(void)
212
213         struct page *dpage;
214
215         down_read(&init_mm.mmap_sem);
216         dpage = xchg(&deferred_pages, NULL);
217         up_read(&init_mm.mmap_sem);
218
219         flush_map((dpage && !dpage->lru.next) ? (unsigned long)page_address(dpage) : 0);
220         while (dpage) {
221                 struct page *tmp = dpage;
222                 dpage = (struct page *)dpage->lru.next;
223                 ClearPagePrivate(tmp);
224                 __free_page(tmp);
225         } 
226
227
228 EXPORT_SYMBOL(change_page_attr);
229 EXPORT_SYMBOL(global_flush_tlb);