2 * linux/arch/arm/mm/flush.c
4 * Copyright (C) 1995-2002 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 #include <linux/module.h>
12 #include <linux/pagemap.h>
14 #include <asm/cacheflush.h>
15 #include <asm/system.h>
16 #include <asm/tlbflush.h>
18 #ifdef CONFIG_CPU_CACHE_VIPT
19 #define ALIAS_FLUSH_START 0xffff4000
21 #define TOP_PTE(x) pte_offset_kernel(top_pmd, x)
23 static void flush_pfn_alias(unsigned long pfn
, unsigned long vaddr
)
25 unsigned long to
= ALIAS_FLUSH_START
+ (CACHE_COLOUR(vaddr
) << PAGE_SHIFT
);
27 set_pte(TOP_PTE(to
), pfn_pte(pfn
, PAGE_KERNEL
));
28 flush_tlb_kernel_page(to
);
30 asm( "mcrr p15, 0, %1, %0, c14\n"
31 " mcrr p15, 0, %1, %0, c5\n"
33 : "r" (to
), "r" (to
+ PAGE_SIZE
- L1_CACHE_BYTES
)
37 #define flush_pfn_alias(pfn,vaddr) do { } while (0)
40 void __flush_dcache_page(struct address_space
*mapping
, struct page
*page
)
43 * Writeback any data associated with the kernel mapping of this
44 * page. This ensures that data in the physical page is mutually
45 * coherent with the kernels mapping.
47 __cpuc_flush_dcache_page(page_address(page
));
50 * If this is a page cache page, and we have an aliasing VIPT cache,
51 * we only need to do one flush - which would be at the relevant
52 * userspace colour, which is congruent with page->index.
54 if (mapping
&& cache_is_vipt_aliasing())
55 flush_pfn_alias(page_to_pfn(page
),
56 page
->index
<< PAGE_CACHE_SHIFT
);
59 static void __flush_dcache_aliases(struct address_space
*mapping
, struct page
*page
)
61 struct mm_struct
*mm
= current
->active_mm
;
62 struct vm_area_struct
*mpnt
;
63 struct prio_tree_iter iter
;
67 * There are possible user space mappings of this page:
68 * - VIVT cache: we need to also write back and invalidate all user
69 * data in the current VM view associated with this page.
70 * - aliasing VIPT: we only need to find one mapping of this page.
72 pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
74 flush_dcache_mmap_lock(mapping
);
75 vma_prio_tree_foreach(mpnt
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
79 * If this VMA is not in our MM, we can ignore it.
81 if (mpnt
->vm_mm
!= mm
)
83 if (!(mpnt
->vm_flags
& VM_MAYSHARE
))
85 offset
= (pgoff
- mpnt
->vm_pgoff
) << PAGE_SHIFT
;
86 flush_cache_page(mpnt
, mpnt
->vm_start
+ offset
, page_to_pfn(page
));
88 flush_dcache_mmap_unlock(mapping
);
92 * Ensure cache coherency between kernel mapping and userspace mapping
95 * We have three cases to consider:
96 * - VIPT non-aliasing cache: fully coherent so nothing required.
97 * - VIVT: fully aliasing, so we need to handle every alias in our
99 * - VIPT aliasing: need to handle one alias in our current VM view.
101 * If we need to handle aliasing:
102 * If the page only exists in the page cache and there are no user
103 * space mappings, we can be lazy and remember that we may have dirty
104 * kernel cache lines for later. Otherwise, we assume we have
107 void flush_dcache_page(struct page
*page
)
109 struct address_space
*mapping
= page_mapping(page
);
111 if (mapping
&& !mapping_mapped(mapping
))
112 set_bit(PG_dcache_dirty
, &page
->flags
);
114 __flush_dcache_page(mapping
, page
);
115 if (mapping
&& cache_is_vivt())
116 __flush_dcache_aliases(mapping
, page
);
119 EXPORT_SYMBOL(flush_dcache_page
);