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66 lines
1.1 KiB
C
66 lines
1.1 KiB
C
/*
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* Handling of the special zero page.
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*
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* Copyright (C) 2007 Bahadir Balban
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*/
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#include <memory.h>
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#include <mm/alloc_page.h>
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#include <l4lib/arch/syscalls.h>
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#include <l4lib/arch/syslib.h>
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#include <string.h>
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#include INC_GLUE(memory.h)
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#include INC_SUBARCH(mm.h)
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#include <l4/generic/space.h>
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#include <arch/mm.h>
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static void *zpage_p;
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static struct page *zpage;
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static struct vm_file devzero;
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void init_zero_page(void)
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{
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void *zpage_v;
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zpage_p = alloc_page(1);
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zpage = phys_to_page(zpage_p);
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/* Map it to self */
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zpage_v = l4_map_helper(zpage_p, 1);
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/* Zero it */
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memset(zpage_v, 0, PAGE_SIZE);
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/* Unmap it */
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l4_unmap_helper(zpage_v, 1);
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/* Update page struct. All other fields are zero */
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zpage->count++;
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}
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void init_devzero(void)
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{
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init_zero_page();
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INIT_LIST_HEAD(&devzero.list);
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INIT_LIST_HEAD(&devzero.page_cache_list);
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devzero.length = (unsigned int)-1;
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devzero.inode.i_addr = -1;
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}
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struct vm_file *get_devzero(void)
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{
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return &devzero;
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}
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void *get_zero_page(void)
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{
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zpage->count++;
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return zpage_p;
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}
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void put_zero_page(void)
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{
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zpage->count--;
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BUG_ON(zpage->count < 0);
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}
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