2 * linux/arch/arm/mm/fault-armv.c
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2002 Russell King
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.
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/kernel.h>
15 #include <linux/bitops.h>
16 #include <linux/vmalloc.h>
17 #include <linux/init.h>
18 #include <linux/pagemap.h>
20 #include <asm/cacheflush.h>
21 #include <asm/cachetype.h>
22 #include <asm/pgtable.h>
23 #include <asm/tlbflush.h>
25 static unsigned long shared_pte_mask = L_PTE_CACHEABLE;
28 * We take the easy way out of this problem - we make the
29 * PTE uncacheable. However, we leave the write buffer on.
31 * Note that the pte lock held when calling update_mmu_cache must also
32 * guard the pte (somewhere else in the same mm) that we modify here.
33 * Therefore those configurations which might call adjust_pte (those
34 * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock.
36 static int adjust_pte(struct vm_area_struct *vma, unsigned long address)
43 pgd = pgd_offset(vma->vm_mm, address);
49 pmd = pmd_offset(pgd, address);
55 pte = pte_offset_map(pmd, address);
59 * If this page is present, it's actually being shared.
61 ret = pte_present(entry);
64 * If this page isn't present, or is already setup to
65 * fault (ie, is old), we can safely ignore any issues.
67 if (ret && pte_val(entry) & shared_pte_mask) {
68 flush_cache_page(vma, address, pte_pfn(entry));
69 pte_val(entry) &= ~shared_pte_mask;
70 set_pte_at(vma->vm_mm, address, pte, entry);
71 flush_tlb_page(vma, address);
90 make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn)
92 struct mm_struct *mm = vma->vm_mm;
93 struct vm_area_struct *mpnt;
94 struct prio_tree_iter iter;
99 pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
102 * If we have any shared mappings that are in the same mm
103 * space, then we need to handle them specially to maintain
106 flush_dcache_mmap_lock(mapping);
107 vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
109 * If this VMA is not in our MM, we can ignore it.
110 * Note that we intentionally mask out the VMA
111 * that we are fixing up.
113 if (mpnt->vm_mm != mm || mpnt == vma)
115 if (!(mpnt->vm_flags & VM_MAYSHARE))
117 offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
118 aliases += adjust_pte(mpnt, mpnt->vm_start + offset);
120 flush_dcache_mmap_unlock(mapping);
122 adjust_pte(vma, addr);
124 flush_cache_page(vma, addr, pfn);
128 * Take care of architecture specific things when placing a new PTE into
129 * a page table, or changing an existing PTE. Basically, there are two
130 * things that we need to take care of:
132 * 1. If PG_dcache_dirty is set for the page, we need to ensure
133 * that any cache entries for the kernels virtual memory
134 * range are written back to the page.
135 * 2. If we have multiple shared mappings of the same space in
136 * an object, we need to deal with the cache aliasing issues.
138 * Note that the pte lock will be held.
140 void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
142 unsigned long pfn = pte_pfn(pte);
143 struct address_space *mapping;
149 page = pfn_to_page(pfn);
150 mapping = page_mapping(page);
153 int dirty = test_and_clear_bit(PG_dcache_dirty, &page->flags);
156 __flush_dcache_page(mapping, page);
160 make_coherent(mapping, vma, addr, pfn);
161 else if (vma->vm_flags & VM_EXEC)
162 __flush_icache_all();
167 * Check whether the write buffer has physical address aliasing
168 * issues. If it has, we need to avoid them for the case where
169 * we have several shared mappings of the same object in user
172 static int __init check_writebuffer(unsigned long *p1, unsigned long *p2)
174 register unsigned long zero = 0, one = 1, val;
188 void __init check_writebuffer_bugs(void)
194 printk(KERN_INFO "CPU: Testing write buffer coherency: ");
196 page = alloc_page(GFP_KERNEL);
198 unsigned long *p1, *p2;
199 pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG|
200 L_PTE_DIRTY|L_PTE_WRITE|
203 p1 = vmap(&page, 1, VM_IOREMAP, prot);
204 p2 = vmap(&page, 1, VM_IOREMAP, prot);
207 v = check_writebuffer(p1, p2);
208 reason = "enabling work-around";
210 reason = "unable to map memory\n";
217 reason = "unable to grab page\n";
221 printk("failed, %s\n", reason);
222 shared_pte_mask |= L_PTE_BUFFERABLE;