blob: 4fbc7de8b4acd199059579cbfd7449f81424a673 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/arch/arm/mm/fault-armv.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2002 Russell King
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11#include <linux/module.h>
12#include <linux/sched.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/bitops.h>
16#include <linux/vmalloc.h>
17#include <linux/init.h>
18#include <linux/pagemap.h>
19
Russell King09d9bae2008-09-05 14:08:44 +010020#include <asm/bugs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <asm/cacheflush.h>
Russell King46097c72008-08-10 18:10:19 +010022#include <asm/cachetype.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <asm/pgtable.h>
24#include <asm/tlbflush.h>
25
Russell Kingbb30f362008-09-06 20:04:59 +010026static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
28/*
29 * We take the easy way out of this problem - we make the
30 * PTE uncacheable. However, we leave the write buffer on.
Hugh Dickins69b04752005-10-29 18:16:36 -070031 *
32 * Note that the pte lock held when calling update_mmu_cache must also
33 * guard the pte (somewhere else in the same mm) that we modify here.
34 * Therefore those configurations which might call adjust_pte (those
35 * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 */
37static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
38{
39 pgd_t *pgd;
40 pmd_t *pmd;
41 pte_t *pte, entry;
Russell King53cdb272008-07-27 10:35:54 +010042 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44 pgd = pgd_offset(vma->vm_mm, address);
45 if (pgd_none(*pgd))
46 goto no_pgd;
47 if (pgd_bad(*pgd))
48 goto bad_pgd;
49
50 pmd = pmd_offset(pgd, address);
51 if (pmd_none(*pmd))
52 goto no_pmd;
53 if (pmd_bad(*pmd))
54 goto bad_pmd;
55
56 pte = pte_offset_map(pmd, address);
57 entry = *pte;
58
59 /*
Russell King53cdb272008-07-27 10:35:54 +010060 * If this page is present, it's actually being shared.
61 */
62 ret = pte_present(entry);
63
64 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 * If this page isn't present, or is already setup to
66 * fault (ie, is old), we can safely ignore any issues.
67 */
Russell Kingbb30f362008-09-06 20:04:59 +010068 if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) {
Nicolas Pitre08e445b2009-01-16 23:02:54 +010069 unsigned long pfn = pte_pfn(entry);
70 flush_cache_page(vma, address, pfn);
71 outer_flush_range((pfn << PAGE_SHIFT),
72 (pfn << PAGE_SHIFT) + PAGE_SIZE);
Russell Kingbb30f362008-09-06 20:04:59 +010073 pte_val(entry) &= ~L_PTE_MT_MASK;
74 pte_val(entry) |= shared_pte_mask;
Russell Kingad1ae2f2006-12-13 14:34:43 +000075 set_pte_at(vma->vm_mm, address, pte, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 flush_tlb_page(vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 }
78 pte_unmap(pte);
79 return ret;
80
81bad_pgd:
82 pgd_ERROR(*pgd);
83 pgd_clear(pgd);
84no_pgd:
85 return 0;
86
87bad_pmd:
88 pmd_ERROR(*pmd);
89 pmd_clear(pmd);
90no_pmd:
91 return 0;
92}
93
94static void
Russell King8830f042005-06-20 09:51:03 +010095make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096{
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 struct mm_struct *mm = vma->vm_mm;
98 struct vm_area_struct *mpnt;
99 struct prio_tree_iter iter;
100 unsigned long offset;
101 pgoff_t pgoff;
102 int aliases = 0;
103
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
105
106 /*
107 * If we have any shared mappings that are in the same mm
108 * space, then we need to handle them specially to maintain
109 * cache coherency.
110 */
111 flush_dcache_mmap_lock(mapping);
112 vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
113 /*
114 * If this VMA is not in our MM, we can ignore it.
115 * Note that we intentionally mask out the VMA
116 * that we are fixing up.
117 */
118 if (mpnt->vm_mm != mm || mpnt == vma)
119 continue;
120 if (!(mpnt->vm_flags & VM_MAYSHARE))
121 continue;
122 offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
123 aliases += adjust_pte(mpnt, mpnt->vm_start + offset);
124 }
125 flush_dcache_mmap_unlock(mapping);
126 if (aliases)
127 adjust_pte(vma, addr);
128 else
Russell King8830f042005-06-20 09:51:03 +0100129 flush_cache_page(vma, addr, pfn);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
132/*
133 * Take care of architecture specific things when placing a new PTE into
134 * a page table, or changing an existing PTE. Basically, there are two
135 * things that we need to take care of:
136 *
137 * 1. If PG_dcache_dirty is set for the page, we need to ensure
138 * that any cache entries for the kernels virtual memory
139 * range are written back to the page.
140 * 2. If we have multiple shared mappings of the same space in
141 * an object, we need to deal with the cache aliasing issues.
142 *
Hugh Dickins69b04752005-10-29 18:16:36 -0700143 * Note that the pte lock will be held.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 */
145void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
146{
147 unsigned long pfn = pte_pfn(pte);
Russell King8830f042005-06-20 09:51:03 +0100148 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 struct page *page;
150
151 if (!pfn_valid(pfn))
152 return;
Russell King8830f042005-06-20 09:51:03 +0100153
Russell King421fe932009-10-25 10:23:04 +0000154 /*
155 * The zero page is never written to, so never has any dirty
156 * cache lines, and therefore never needs to be flushed.
157 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 page = pfn_to_page(pfn);
Russell King421fe932009-10-25 10:23:04 +0000159 if (page == ZERO_PAGE(0))
160 return;
161
Russell King8830f042005-06-20 09:51:03 +0100162 mapping = page_mapping(page);
Catalin Marinas826cbda2008-06-13 10:28:36 +0100163#ifndef CONFIG_SMP
Nitin Gupta787b2fa2009-10-12 14:20:23 +0530164 if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
165 __flush_dcache_page(mapping, page);
Catalin Marinas826cbda2008-06-13 10:28:36 +0100166#endif
Nitin Gupta787b2fa2009-10-12 14:20:23 +0530167 if (mapping) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 if (cache_is_vivt())
Russell King8830f042005-06-20 09:51:03 +0100169 make_coherent(mapping, vma, addr, pfn);
Catalin Marinas826cbda2008-06-13 10:28:36 +0100170 else if (vma->vm_flags & VM_EXEC)
171 __flush_icache_all();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 }
173}
174
175/*
176 * Check whether the write buffer has physical address aliasing
177 * issues. If it has, we need to avoid them for the case where
178 * we have several shared mappings of the same object in user
179 * space.
180 */
181static int __init check_writebuffer(unsigned long *p1, unsigned long *p2)
182{
183 register unsigned long zero = 0, one = 1, val;
184
185 local_irq_disable();
186 mb();
187 *p1 = one;
188 mb();
189 *p2 = zero;
190 mb();
191 val = *p1;
192 mb();
193 local_irq_enable();
194 return val != zero;
195}
196
197void __init check_writebuffer_bugs(void)
198{
199 struct page *page;
200 const char *reason;
201 unsigned long v = 1;
202
203 printk(KERN_INFO "CPU: Testing write buffer coherency: ");
204
205 page = alloc_page(GFP_KERNEL);
206 if (page) {
207 unsigned long *p1, *p2;
208 pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG|
209 L_PTE_DIRTY|L_PTE_WRITE|
Russell Kingbb30f362008-09-06 20:04:59 +0100210 L_PTE_MT_BUFFERABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211
212 p1 = vmap(&page, 1, VM_IOREMAP, prot);
213 p2 = vmap(&page, 1, VM_IOREMAP, prot);
214
215 if (p1 && p2) {
216 v = check_writebuffer(p1, p2);
217 reason = "enabling work-around";
218 } else {
219 reason = "unable to map memory\n";
220 }
221
222 vunmap(p1);
223 vunmap(p2);
224 put_page(page);
225 } else {
226 reason = "unable to grab page\n";
227 }
228
229 if (v) {
230 printk("failed, %s\n", reason);
Russell Kingbb30f362008-09-06 20:04:59 +0100231 shared_pte_mask = L_PTE_MT_UNCACHED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 } else {
233 printk("ok\n");
234 }
235}