0887b34bc59b987543c10b92ae53d73b83c361ef
[linux-2.6.git] / arch / i386 / 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/pgalloc.h>
16 #include <asm/sections.h>
17
18 static DEFINE_SPINLOCK(cpa_lock);
19 static struct list_head df_list = LIST_HEAD_INIT(df_list);
20
21
22 pte_t *lookup_address(unsigned long address) 
23
24         pgd_t *pgd = pgd_offset_k(address);
25         pud_t *pud;
26         pmd_t *pmd;
27         if (pgd_none(*pgd))
28                 return NULL;
29         pud = pud_offset(pgd, address);
30         if (pud_none(*pud))
31                 return NULL;
32         pmd = pmd_offset(pud, address);
33         if (pmd_none(*pmd))
34                 return NULL;
35         if (pmd_large(*pmd))
36                 return (pte_t *)pmd;
37         return pte_offset_kernel(pmd, address);
38
39
40 static struct page *split_large_page(unsigned long address, pgprot_t prot,
41                                         pgprot_t ref_prot)
42
43         int i; 
44         unsigned long addr;
45         struct page *base;
46         pte_t *pbase;
47
48         spin_unlock_irq(&cpa_lock);
49         base = alloc_pages(GFP_KERNEL, 0);
50         spin_lock_irq(&cpa_lock);
51         if (!base) 
52                 return NULL;
53
54         /*
55          * page_private is used to track the number of entries in
56          * the page table page that have non standard attributes.
57          */
58         SetPagePrivate(base);
59         page_private(base) = 0;
60
61         address = __pa(address);
62         addr = address & LARGE_PAGE_MASK; 
63         pbase = (pte_t *)page_address(base);
64         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
65                set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
66                                           addr == address ? prot : ref_prot));
67         }
68         return base;
69
70
71 static void flush_kernel_map(void *dummy) 
72
73         /* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
74         if (boot_cpu_data.x86_model >= 4) 
75                 wbinvd();
76         /* Flush all to work around Errata in early athlons regarding 
77          * large page flushing. 
78          */
79         __flush_tlb_all();      
80 }
81
82 static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
83
84         struct page *page;
85         unsigned long flags;
86
87         set_pte_atomic(kpte, pte);      /* change init_mm */
88         if (PTRS_PER_PMD > 1)
89                 return;
90
91         spin_lock_irqsave(&pgd_lock, flags);
92         for (page = pgd_list; page; page = (struct page *)page->index) {
93                 pgd_t *pgd;
94                 pud_t *pud;
95                 pmd_t *pmd;
96                 pgd = (pgd_t *)page_address(page) + pgd_index(address);
97                 pud = pud_offset(pgd, address);
98                 pmd = pmd_offset(pud, address);
99                 set_pte_atomic((pte_t *)pmd, pte);
100         }
101         spin_unlock_irqrestore(&pgd_lock, flags);
102 }
103
104 /* 
105  * No more special protections in this 2/4MB area - revert to a
106  * large page again. 
107  */
108 static inline void revert_page(struct page *kpte_page, unsigned long address)
109 {
110         pgprot_t ref_prot;
111         pte_t *linear;
112
113         ref_prot =
114         ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
115                 ? PAGE_KERNEL_LARGE_EXEC : PAGE_KERNEL_LARGE;
116
117         linear = (pte_t *)
118                 pmd_offset(pud_offset(pgd_offset_k(address), address), address);
119         set_pmd_pte(linear,  address,
120                     pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
121                             ref_prot));
122 }
123
124 static int
125 __change_page_attr(struct page *page, pgprot_t prot)
126
127         pte_t *kpte; 
128         unsigned long address;
129         struct page *kpte_page;
130
131         BUG_ON(PageHighMem(page));
132         address = (unsigned long)page_address(page);
133
134         kpte = lookup_address(address);
135         if (!kpte)
136                 return -EINVAL;
137         kpte_page = virt_to_page(kpte);
138         if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 
139                 if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
140                         set_pte_atomic(kpte, mk_pte(page, prot)); 
141                 } else {
142                         pgprot_t ref_prot;
143                         struct page *split;
144
145                         ref_prot =
146                         ((address & LARGE_PAGE_MASK) < (unsigned long)&_etext)
147                                 ? PAGE_KERNEL_EXEC : PAGE_KERNEL;
148                         split = split_large_page(address, prot, ref_prot);
149                         if (!split)
150                                 return -ENOMEM;
151                         set_pmd_pte(kpte,address,mk_pte(split, ref_prot));
152                         kpte_page = split;
153                 }
154                 page_private(kpte_page)++;
155         } else if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
156                 set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
157                 BUG_ON(page_private(kpte_page) == 0);
158                 page_private(kpte_page)--;
159         } else
160                 BUG();
161
162         /*
163          * If the pte was reserved, it means it was created at boot
164          * time (not via split_large_page) and in turn we must not
165          * replace it with a largepage.
166          */
167         if (!PageReserved(kpte_page)) {
168                 if (cpu_has_pse && (page_private(kpte_page) == 0)) {
169                         ClearPagePrivate(kpte_page);
170                         list_add(&kpte_page->lru, &df_list);
171                         revert_page(kpte_page, address);
172                 }
173         }
174         return 0;
175
176
177 static inline void flush_map(void)
178 {
179         on_each_cpu(flush_kernel_map, NULL, 1, 1);
180 }
181
182 /*
183  * Change the page attributes of an page in the linear mapping.
184  *
185  * This should be used when a page is mapped with a different caching policy
186  * than write-back somewhere - some CPUs do not like it when mappings with
187  * different caching policies exist. This changes the page attributes of the
188  * in kernel linear mapping too.
189  * 
190  * The caller needs to ensure that there are no conflicting mappings elsewhere.
191  * This function only deals with the kernel linear map.
192  * 
193  * Caller must call global_flush_tlb() after this.
194  */
195 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
196 {
197         int err = 0; 
198         int i; 
199         unsigned long flags;
200
201         spin_lock_irqsave(&cpa_lock, flags);
202         for (i = 0; i < numpages; i++, page++) { 
203                 err = __change_page_attr(page, prot);
204                 if (err) 
205                         break; 
206         }       
207         spin_unlock_irqrestore(&cpa_lock, flags);
208         return err;
209 }
210
211 void global_flush_tlb(void)
212 {
213         struct list_head l;
214         struct page *pg, *next;
215
216         BUG_ON(irqs_disabled());
217
218         spin_lock_irq(&cpa_lock);
219         list_replace_init(&df_list, &l);
220         spin_unlock_irq(&cpa_lock);
221         flush_map();
222         list_for_each_entry_safe(pg, next, &l, lru)
223                 __free_page(pg);
224 }
225
226 #ifdef CONFIG_DEBUG_PAGEALLOC
227 void kernel_map_pages(struct page *page, int numpages, int enable)
228 {
229         if (PageHighMem(page))
230                 return;
231         if (!enable)
232                 mutex_debug_check_no_locks_freed(page_address(page),
233                                                  numpages * PAGE_SIZE);
234
235         /* the return value is ignored - the calls cannot fail,
236          * large pages are disabled at boot time.
237          */
238         change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
239         /* we should perform an IPI and flush all tlbs,
240          * but that can deadlock->flush only current cpu.
241          */
242         __flush_tlb_all();
243 }
244 #endif
245
246 EXPORT_SYMBOL(change_page_attr);
247 EXPORT_SYMBOL(global_flush_tlb);