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PAE mode requires that we reload cr3 in order to guarantee that changes to the pgd will be noticed by the processor. This means that in principle pud_clear needs to reload cr3 every time. However, because reloading cr3 implies a tlb flush, we want to avoid it where possible. pud_clear() is only used in a couple of places: - in free_pmd_range(), when pulling down a range of process address space, and - huge_pmd_unshare() In both cases, the calling code will do a a tlb flush anyway, so there's no need to do it within pud_clear(). In free_pmd_range(), the pud_clear is immediately followed by pmd_free_tlb(); we can hook that to make the mmu_gather do an unconditional full flush to make sure cr3 gets reloaded. In huge_pmd_unshare, it is followed by flush_tlb_range, which always results in a full cr3-reload tlb flush. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: William Irwin <wli@holomorphy.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
178 lines
4.9 KiB
C
178 lines
4.9 KiB
C
#ifndef _I386_PGTABLE_3LEVEL_H
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#define _I386_PGTABLE_3LEVEL_H
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/*
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* Intel Physical Address Extension (PAE) Mode - three-level page
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* tables on PPro+ CPUs.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#define pte_ERROR(e) \
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printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, &(e), (e).pte_high, (e).pte_low)
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#define pmd_ERROR(e) \
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printk("%s:%d: bad pmd %p(%016Lx).\n", __FILE__, __LINE__, &(e), pmd_val(e))
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#define pgd_ERROR(e) \
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printk("%s:%d: bad pgd %p(%016Lx).\n", __FILE__, __LINE__, &(e), pgd_val(e))
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static inline int pud_none(pud_t pud)
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{
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return pud_val(pud) == 0;
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}
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static inline int pud_bad(pud_t pud)
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{
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return (pud_val(pud) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER)) != 0;
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}
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static inline int pud_present(pud_t pud)
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{
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return pud_val(pud) & _PAGE_PRESENT;
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}
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/* Rules for using set_pte: the pte being assigned *must* be
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* either not present or in a state where the hardware will
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* not attempt to update the pte. In places where this is
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* not possible, use pte_get_and_clear to obtain the old pte
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* value and then use set_pte to update it. -ben
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*/
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static inline void native_set_pte(pte_t *ptep, pte_t pte)
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{
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ptep->pte_high = pte.pte_high;
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smp_wmb();
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ptep->pte_low = pte.pte_low;
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}
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/*
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* Since this is only called on user PTEs, and the page fault handler
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* must handle the already racy situation of simultaneous page faults,
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* we are justified in merely clearing the PTE present bit, followed
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* by a set. The ordering here is important.
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*/
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static inline void native_set_pte_present(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep, pte_t pte)
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{
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ptep->pte_low = 0;
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smp_wmb();
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ptep->pte_high = pte.pte_high;
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smp_wmb();
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ptep->pte_low = pte.pte_low;
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}
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static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
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{
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set_64bit((unsigned long long *)(ptep),native_pte_val(pte));
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}
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static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
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{
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set_64bit((unsigned long long *)(pmdp),native_pmd_val(pmd));
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}
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static inline void native_set_pud(pud_t *pudp, pud_t pud)
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{
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set_64bit((unsigned long long *)(pudp),native_pud_val(pud));
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}
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/*
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* For PTEs and PDEs, we must clear the P-bit first when clearing a page table
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* entry, so clear the bottom half first and enforce ordering with a compiler
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* barrier.
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*/
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static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
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{
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ptep->pte_low = 0;
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smp_wmb();
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ptep->pte_high = 0;
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}
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static inline void native_pmd_clear(pmd_t *pmd)
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{
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u32 *tmp = (u32 *)pmd;
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*tmp = 0;
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smp_wmb();
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*(tmp + 1) = 0;
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}
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static inline void pud_clear(pud_t *pudp)
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{
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set_pud(pudp, __pud(0));
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/*
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* In principle we need to do a cr3 reload here to make sure
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* the processor recognizes the changed pgd. In practice, all
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* the places where pud_clear() gets called are followed by
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* full tlb flushes anyway, so we can defer the cost here.
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*
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* Specifically:
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*
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* mm/memory.c:free_pmd_range() - immediately after the
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* pud_clear() it does a pmd_free_tlb(). We change the
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* mmu_gather structure to do a full tlb flush (which has the
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* effect of reloading cr3) when the pagetable free is
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* complete.
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*
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* arch/x86/mm/hugetlbpage.c:huge_pmd_unshare() - the call to
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* this is followed by a flush_tlb_range, which on x86 does a
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* full tlb flush.
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*/
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}
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#define pud_page(pud) \
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((struct page *) __va(pud_val(pud) & PAGE_MASK))
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#define pud_page_vaddr(pud) \
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((unsigned long) __va(pud_val(pud) & PAGE_MASK))
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/* Find an entry in the second-level page table.. */
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#define pmd_offset(pud, address) ((pmd_t *) pud_page(*(pud)) + \
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pmd_index(address))
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#ifdef CONFIG_SMP
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static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
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{
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pte_t res;
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/* xchg acts as a barrier before the setting of the high bits */
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res.pte_low = xchg(&ptep->pte_low, 0);
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res.pte_high = ptep->pte_high;
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ptep->pte_high = 0;
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return res;
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}
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#else
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#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
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#endif
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#define __HAVE_ARCH_PTE_SAME
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static inline int pte_same(pte_t a, pte_t b)
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{
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return a.pte_low == b.pte_low && a.pte_high == b.pte_high;
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}
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#define pte_page(x) pfn_to_page(pte_pfn(x))
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static inline int pte_none(pte_t pte)
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{
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return !pte.pte_low && !pte.pte_high;
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}
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static inline unsigned long pte_pfn(pte_t pte)
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{
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return (pte_val(pte) & ~_PAGE_NX) >> PAGE_SHIFT;
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}
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/*
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* Bits 0, 6 and 7 are taken in the low part of the pte,
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* put the 32 bits of offset into the high part.
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*/
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#define pte_to_pgoff(pte) ((pte).pte_high)
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#define pgoff_to_pte(off) ((pte_t) { { .pte_low = _PAGE_FILE, .pte_high = (off) } })
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#define PTE_FILE_MAX_BITS 32
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/* Encode and de-code a swap entry */
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#define __swp_type(x) (((x).val) & 0x1f)
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#define __swp_offset(x) ((x).val >> 5)
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#define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) << 5})
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#define __pte_to_swp_entry(pte) ((swp_entry_t){ (pte).pte_high })
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#define __swp_entry_to_pte(x) ((pte_t){ { .pte_high = (x).val } })
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#endif /* _I386_PGTABLE_3LEVEL_H */
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