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86df864249
As Andy Whitcroft recently pointed out, the current powerpc version of
huge_ptep_set_wrprotect() has a bug. It just calls ptep_set_wrprotect()
which in turn calls pte_update() then hpte_need_flush() with the 'huge'
argument set to 0. This will cause hpte_need_flush() to flush the wrong
hash entries (of any). Andy's fix for this is already in the powerpc
tree as commit 016b33c495.
I have confirmed this is a real bug, not masked by some other
synchronization, with a new testcase for libhugetlbfs. A process write
a (MAP_PRIVATE) hugepage mapping, fork(), then alter the mapping and
have the child incorrectly see the second write.
Therefore, this should be fixed for 2.6.26, and for the stable tree.
Here is a suitable patch for 2.6.26, which I think will also be suitable
for the stable tree (neither of the headers in question has been changed
much recently).
It is cut down slighlty from Andy's original version, in that it does
not include a 32-bit version of huge_ptep_set_wrprotect(). Currently,
hugepages are not supported on any 32-bit powerpc platform. When they
are, a suitable 32-bit version can be added - the only 32-bit hardware
which supports hugepages does not use the conventional hashtable MMU and
so will have different needs anyway.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
#ifndef _ASM_POWERPC_HUGETLB_H
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#define _ASM_POWERPC_HUGETLB_H
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#include <asm/page.h>
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int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
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unsigned long len);
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void hugetlb_free_pgd_range(struct mmu_gather **tlb, unsigned long addr,
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unsigned long end, unsigned long floor,
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unsigned long ceiling);
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void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pte);
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pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep);
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/*
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* If the arch doesn't supply something else, assume that hugepage
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* size aligned regions are ok without further preparation.
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*/
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static inline int prepare_hugepage_range(unsigned long addr, unsigned long len)
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{
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if (len & ~HPAGE_MASK)
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return -EINVAL;
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if (addr & ~HPAGE_MASK)
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return -EINVAL;
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return 0;
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}
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static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm)
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{
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}
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static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
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unsigned long addr, pte_t *ptep)
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{
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}
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static inline int huge_pte_none(pte_t pte)
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{
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return pte_none(pte);
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}
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static inline pte_t huge_pte_wrprotect(pte_t pte)
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{
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return pte_wrprotect(pte);
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}
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static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
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unsigned long addr, pte_t *ptep,
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pte_t pte, int dirty)
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{
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return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
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}
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static inline pte_t huge_ptep_get(pte_t *ptep)
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{
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return *ptep;
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}
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static inline int arch_prepare_hugepage(struct page *page)
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{
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return 0;
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}
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static inline void arch_release_hugepage(struct page *page)
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{
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}
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#endif /* _ASM_POWERPC_HUGETLB_H */
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