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/*
* linux/arch/arm/mm/flush.c
*
* Copyright (C) 1995-2002 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <asm/cacheflush.h>
#include <asm/system.h>
#include <asm/tlbflush.h>
#ifdef CONFIG_CPU_CACHE_VIPT
#define ALIAS_FLUSH_START 0xffff4000
#define TOP_PTE(x) pte_offset_kernel(top_pmd, x)
static void flush_pfn_alias(unsigned long pfn, unsigned long vaddr)
{
unsigned long to = ALIAS_FLUSH_START + (CACHE_COLOUR(vaddr) << PAGE_SHIFT);
set_pte(TOP_PTE(to), pfn_pte(pfn, PAGE_KERNEL));
flush_tlb_kernel_page(to);
asm( "mcrr p15, 0, %1, %0, c14\n"
" mcrr p15, 0, %1, %0, c5\n"
:
: "r" (to), "r" (to + PAGE_SIZE - L1_CACHE_BYTES)
: "cc");
}
#else
#define flush_pfn_alias(pfn,vaddr) do { } while (0)
#endif
static void __flush_dcache_page(struct address_space *mapping, struct page *page)
{
struct mm_struct *mm = current->active_mm;
struct vm_area_struct *mpnt;
struct prio_tree_iter iter;
pgoff_t pgoff;
/*
* Writeback any data associated with the kernel mapping of this
* page. This ensures that data in the physical page is mutually
* coherent with the kernels mapping.
*/
__cpuc_flush_dcache_page(page_address(page));
/*
* If there's no mapping pointer here, then this page isn't
* visible to userspace yet, so there are no cache lines
* associated with any other aliases.
*/
if (!mapping)
return;
/*
* This is a page cache page. If we have a VIPT cache, we
* only need to do one flush - which would be at the relevant
* userspace colour, which is congruent with page->index.
*/
if (cache_is_vipt()) {
if (cache_is_vipt_aliasing())
flush_pfn_alias(page_to_pfn(page),
page->index << PAGE_CACHE_SHIFT);
return;
}
/*
* There are possible user space mappings of this page:
* - VIVT cache: we need to also write back and invalidate all user
* data in the current VM view associated with this page.
* - aliasing VIPT: we only need to find one mapping of this page.
*/
pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
flush_dcache_mmap_lock(mapping);
vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
unsigned long offset;
/*
* If this VMA is not in our MM, we can ignore it.
*/
if (mpnt->vm_mm != mm)
continue;
if (!(mpnt->vm_flags & VM_MAYSHARE))
continue;
offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
flush_cache_page(mpnt, mpnt->vm_start + offset, page_to_pfn(page));
}
flush_dcache_mmap_unlock(mapping);
}
/*
* Ensure cache coherency between kernel mapping and userspace mapping
* of this page.
*
* We have three cases to consider:
* - VIPT non-aliasing cache: fully coherent so nothing required.
* - VIVT: fully aliasing, so we need to handle every alias in our
* current VM view.
* - VIPT aliasing: need to handle one alias in our current VM view.
*
* If we need to handle aliasing:
* If the page only exists in the page cache and there are no user
* space mappings, we can be lazy and remember that we may have dirty
* kernel cache lines for later. Otherwise, we assume we have
* aliasing mappings.
*/
void flush_dcache_page(struct page *page)
{
struct address_space *mapping = page_mapping(page);
if (cache_is_vipt_nonaliasing())
return;
if (mapping && !mapping_mapped(mapping))
set_bit(PG_dcache_dirty, &page->flags);
else
__flush_dcache_page(mapping, page);
}
EXPORT_SYMBOL(flush_dcache_page);
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