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cb9f753a37
Thanks to commit 4b3ef9daa4
("mm/swap: split swap cache into 64MB
trunks"), after swapoff the address_space associated with the swap
device will be freed. So page_mapping() users which may touch the
address_space need some kind of mechanism to prevent the address_space
from being freed during accessing.
The dcache flushing functions (flush_dcache_page(), etc) in architecture
specific code may access the address_space of swap device for anonymous
pages in swap cache via page_mapping() function. But in some cases
there are no mechanisms to prevent the swap device from being swapoff,
for example,
CPU1 CPU2
__get_user_pages() swapoff()
flush_dcache_page()
mapping = page_mapping()
... exit_swap_address_space()
... kvfree(spaces)
mapping_mapped(mapping)
The address space may be accessed after being freed.
But from cachetlb.txt and Russell King, flush_dcache_page() only care
about file cache pages, for anonymous pages, flush_anon_page() should be
used. The implementation of flush_dcache_page() in all architectures
follows this too. They will check whether page_mapping() is NULL and
whether mapping_mapped() is true to determine whether to flush the
dcache immediately. And they will use interval tree (mapping->i_mmap)
to find all user space mappings. While mapping_mapped() and
mapping->i_mmap isn't used by anonymous pages in swap cache at all.
So, to fix the race between swapoff and flush dcache, __page_mapping()
is add to return the address_space for file cache pages and NULL
otherwise. All page_mapping() invoking in flush dcache functions are
replaced with page_mapping_file().
[akpm@linux-foundation.org: simplify page_mapping_file(), per Mike]
Link: http://lkml.kernel.org/r/20180305083634.15174-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Zankel <chris@zankel.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
247 lines
7.3 KiB
C
247 lines
7.3 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1994 - 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
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* Copyright (C) 2007 MIPS Technologies, Inc.
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*/
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#include <linux/fs.h>
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#include <linux/fcntl.h>
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#include <linux/kernel.h>
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#include <linux/linkage.h>
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <linux/mm.h>
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#include <asm/cacheflush.h>
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#include <asm/highmem.h>
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#include <asm/processor.h>
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#include <asm/cpu.h>
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#include <asm/cpu-features.h>
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#include <asm/setup.h>
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/* Cache operations. */
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void (*flush_cache_all)(void);
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void (*__flush_cache_all)(void);
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EXPORT_SYMBOL_GPL(__flush_cache_all);
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void (*flush_cache_mm)(struct mm_struct *mm);
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void (*flush_cache_range)(struct vm_area_struct *vma, unsigned long start,
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unsigned long end);
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void (*flush_cache_page)(struct vm_area_struct *vma, unsigned long page,
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unsigned long pfn);
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void (*flush_icache_range)(unsigned long start, unsigned long end);
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EXPORT_SYMBOL_GPL(flush_icache_range);
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void (*local_flush_icache_range)(unsigned long start, unsigned long end);
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EXPORT_SYMBOL_GPL(local_flush_icache_range);
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void (*__flush_icache_user_range)(unsigned long start, unsigned long end);
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EXPORT_SYMBOL_GPL(__flush_icache_user_range);
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void (*__local_flush_icache_user_range)(unsigned long start, unsigned long end);
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EXPORT_SYMBOL_GPL(__local_flush_icache_user_range);
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void (*__flush_cache_vmap)(void);
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void (*__flush_cache_vunmap)(void);
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void (*__flush_kernel_vmap_range)(unsigned long vaddr, int size);
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EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range);
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/* MIPS specific cache operations */
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void (*flush_cache_sigtramp)(unsigned long addr);
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void (*local_flush_data_cache_page)(void * addr);
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void (*flush_data_cache_page)(unsigned long addr);
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void (*flush_icache_all)(void);
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EXPORT_SYMBOL_GPL(local_flush_data_cache_page);
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EXPORT_SYMBOL(flush_data_cache_page);
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EXPORT_SYMBOL(flush_icache_all);
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#if defined(CONFIG_DMA_NONCOHERENT) || defined(CONFIG_DMA_MAYBE_COHERENT)
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/* DMA cache operations. */
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void (*_dma_cache_wback_inv)(unsigned long start, unsigned long size);
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void (*_dma_cache_wback)(unsigned long start, unsigned long size);
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void (*_dma_cache_inv)(unsigned long start, unsigned long size);
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EXPORT_SYMBOL(_dma_cache_wback_inv);
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#endif /* CONFIG_DMA_NONCOHERENT || CONFIG_DMA_MAYBE_COHERENT */
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/*
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* We could optimize the case where the cache argument is not BCACHE but
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* that seems very atypical use ...
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*/
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SYSCALL_DEFINE3(cacheflush, unsigned long, addr, unsigned long, bytes,
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unsigned int, cache)
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{
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if (bytes == 0)
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return 0;
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if (!access_ok(VERIFY_WRITE, (void __user *) addr, bytes))
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return -EFAULT;
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__flush_icache_user_range(addr, addr + bytes);
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return 0;
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}
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void __flush_dcache_page(struct page *page)
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{
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struct address_space *mapping = page_mapping_file(page);
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unsigned long addr;
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if (mapping && !mapping_mapped(mapping)) {
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SetPageDcacheDirty(page);
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return;
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}
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/*
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* We could delay the flush for the !page_mapping case too. But that
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* case is for exec env/arg pages and those are %99 certainly going to
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* get faulted into the tlb (and thus flushed) anyways.
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*/
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if (PageHighMem(page))
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addr = (unsigned long)kmap_atomic(page);
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else
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addr = (unsigned long)page_address(page);
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flush_data_cache_page(addr);
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if (PageHighMem(page))
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__kunmap_atomic((void *)addr);
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}
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EXPORT_SYMBOL(__flush_dcache_page);
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void __flush_anon_page(struct page *page, unsigned long vmaddr)
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{
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unsigned long addr = (unsigned long) page_address(page);
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if (pages_do_alias(addr, vmaddr)) {
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if (page_mapcount(page) && !Page_dcache_dirty(page)) {
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void *kaddr;
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kaddr = kmap_coherent(page, vmaddr);
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flush_data_cache_page((unsigned long)kaddr);
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kunmap_coherent();
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} else
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flush_data_cache_page(addr);
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}
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}
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EXPORT_SYMBOL(__flush_anon_page);
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void __update_cache(unsigned long address, pte_t pte)
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{
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struct page *page;
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unsigned long pfn, addr;
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int exec = !pte_no_exec(pte) && !cpu_has_ic_fills_f_dc;
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pfn = pte_pfn(pte);
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if (unlikely(!pfn_valid(pfn)))
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return;
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page = pfn_to_page(pfn);
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if (Page_dcache_dirty(page)) {
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if (PageHighMem(page))
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addr = (unsigned long)kmap_atomic(page);
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else
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addr = (unsigned long)page_address(page);
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if (exec || pages_do_alias(addr, address & PAGE_MASK))
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flush_data_cache_page(addr);
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if (PageHighMem(page))
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__kunmap_atomic((void *)addr);
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ClearPageDcacheDirty(page);
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}
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}
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unsigned long _page_cachable_default;
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EXPORT_SYMBOL(_page_cachable_default);
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static inline void setup_protection_map(void)
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{
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if (cpu_has_rixi) {
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protection_map[0] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
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protection_map[1] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
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protection_map[2] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
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protection_map[3] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
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protection_map[4] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[5] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[6] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[7] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[8] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
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protection_map[9] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
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protection_map[10] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | _PAGE_NO_READ);
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protection_map[11] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE);
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protection_map[12] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[13] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
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protection_map[14] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE);
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protection_map[15] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE);
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} else {
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protection_map[0] = PAGE_NONE;
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protection_map[1] = PAGE_READONLY;
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protection_map[2] = PAGE_COPY;
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protection_map[3] = PAGE_COPY;
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protection_map[4] = PAGE_READONLY;
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protection_map[5] = PAGE_READONLY;
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protection_map[6] = PAGE_COPY;
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protection_map[7] = PAGE_COPY;
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protection_map[8] = PAGE_NONE;
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protection_map[9] = PAGE_READONLY;
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protection_map[10] = PAGE_SHARED;
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protection_map[11] = PAGE_SHARED;
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protection_map[12] = PAGE_READONLY;
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protection_map[13] = PAGE_READONLY;
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protection_map[14] = PAGE_SHARED;
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protection_map[15] = PAGE_SHARED;
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}
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}
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void cpu_cache_init(void)
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{
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if (cpu_has_3k_cache) {
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extern void __weak r3k_cache_init(void);
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r3k_cache_init();
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}
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if (cpu_has_6k_cache) {
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extern void __weak r6k_cache_init(void);
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r6k_cache_init();
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}
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if (cpu_has_4k_cache) {
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extern void __weak r4k_cache_init(void);
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r4k_cache_init();
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}
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if (cpu_has_8k_cache) {
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extern void __weak r8k_cache_init(void);
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r8k_cache_init();
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}
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if (cpu_has_tx39_cache) {
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extern void __weak tx39_cache_init(void);
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tx39_cache_init();
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}
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if (cpu_has_octeon_cache) {
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extern void __weak octeon_cache_init(void);
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octeon_cache_init();
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}
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setup_protection_map();
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}
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int __weak __uncached_access(struct file *file, unsigned long addr)
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{
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if (file->f_flags & O_DSYNC)
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return 1;
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return addr >= __pa(high_memory);
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}
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