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https://github.com/torvalds/linux
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6ad8d010b2
I think we have a subtle race on ppc64 with the tlb batching. The common code expects tlb_flush() to actually flush any pending TLB batch. It does that because it delays all page freeing until after tlb_flush() is called, in order to ensure no stale reference to those pages exist in any TLB, thus causing potential access to the freed pages. However, our tlb_flush only triggers the RCU for freeing page table pages, it does not currently trigger a flush of a pending TLB/hash batch, which is, I think, an error. This fixes it. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/*
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* TLB shootdown specifics for powerpc
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*
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* Copyright (C) 2002 Anton Blanchard, IBM Corp.
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* Copyright (C) 2002 Paul Mackerras, IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_TLB_H
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#define _ASM_POWERPC_TLB_H
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#ifdef __KERNEL__
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#ifndef __powerpc64__
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#include <asm/pgtable.h>
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#endif
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#include <asm/pgalloc.h>
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#include <asm/tlbflush.h>
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#ifndef __powerpc64__
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#include <asm/page.h>
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#include <asm/mmu.h>
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#endif
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struct mmu_gather;
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#define tlb_start_vma(tlb, vma) do { } while (0)
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#define tlb_end_vma(tlb, vma) do { } while (0)
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#if !defined(CONFIG_PPC_STD_MMU)
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#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
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#elif defined(__powerpc64__)
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extern void pte_free_finish(void);
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static inline void tlb_flush(struct mmu_gather *tlb)
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{
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struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch);
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/* If there's a TLB batch pending, then we must flush it because the
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* pages are going to be freed and we really don't want to have a CPU
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* access a freed page because it has a stale TLB
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*/
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if (tlbbatch->index)
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__flush_tlb_pending(tlbbatch);
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pte_free_finish();
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}
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#else
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extern void tlb_flush(struct mmu_gather *tlb);
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#endif
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/* Get the generic bits... */
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#include <asm-generic/tlb.h>
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#if !defined(CONFIG_PPC_STD_MMU) || defined(__powerpc64__)
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#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
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#else
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extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
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unsigned long address);
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static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
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unsigned long address)
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{
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if (pte_val(*ptep) & _PAGE_HASHPTE)
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flush_hash_entry(tlb->mm, ptep, address);
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}
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#endif
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#endif /* __KERNEL__ */
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#endif /* __ASM_POWERPC_TLB_H */
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