dc068f4621
The non-MMU m68k pagetable ZERO_PAGE() macro is being set to the somewhat non-sensical value of "virt_to_page(0)". The zeroth page is not in any way guaranteed to be a page full of "0". So the result is that ZERO_PAGE() will almost certainly contain random values. We already allocate a real "empty_zero_page" in the mm setup code shared between MMU m68k and non-MMU m68k. It is just not hooked up to the ZERO_PAGE() macro for the non-MMU m68k case. Fix ZERO_PAGE() to use the allocated "empty_zero_page" pointer. I am not aware of any specific issues caused by the old code. Link: https://lore.kernel.org/linux-m68k/2a462b23-5b8e-bbf4-ec7d-778434a3b9d7@google.com/T/#t Reported-by: Hugh Dickens <hughd@google.com> Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
58 lines
1.4 KiB
C
58 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _M68KNOMMU_PGTABLE_H
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#define _M68KNOMMU_PGTABLE_H
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#include <asm-generic/pgtable-nopud.h>
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/*
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* (C) Copyright 2000-2002, Greg Ungerer <gerg@snapgear.com>
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*/
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#include <linux/slab.h>
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#include <asm/processor.h>
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#include <asm/page.h>
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#include <asm/io.h>
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/*
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* Trivial page table functions.
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*/
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#define pgd_present(pgd) (1)
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#define pgd_none(pgd) (0)
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#define pgd_bad(pgd) (0)
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#define pgd_clear(pgdp)
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#define kern_addr_valid(addr) (1)
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#define pmd_offset(a, b) ((void *)0)
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#define PAGE_NONE __pgprot(0)
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#define PAGE_SHARED __pgprot(0)
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#define PAGE_COPY __pgprot(0)
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#define PAGE_READONLY __pgprot(0)
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#define PAGE_KERNEL __pgprot(0)
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extern void paging_init(void);
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#define swapper_pg_dir ((pgd_t *) 0)
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#define __swp_type(x) (0)
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#define __swp_offset(x) (0)
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#define __swp_entry(typ,off) ((swp_entry_t) { ((typ) | ((off) << 7)) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
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#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
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/*
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* ZERO_PAGE is a global shared page that is always zero: used
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* for zero-mapped memory areas etc..
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*/
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extern void *empty_zero_page;
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#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
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/*
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* All 32bit addresses are effectively valid for vmalloc...
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* Sort of meaningless for non-VM targets.
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*/
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#define VMALLOC_START 0
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#define VMALLOC_END 0xffffffff
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#define KMAP_START 0
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#define KMAP_END 0xffffffff
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#endif /* _M68KNOMMU_PGTABLE_H */
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