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linux-next/include/asm-powerpc/tlb.h
Benjamin Herrenschmidt 6ad8d010b2 [POWERPC] Fix possible access to free pages
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>
2007-06-02 21:01:55 +10:00

80 lines
1.9 KiB
C

/*
* TLB shootdown specifics for powerpc
*
* Copyright (C) 2002 Anton Blanchard, IBM Corp.
* Copyright (C) 2002 Paul Mackerras, IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_POWERPC_TLB_H
#define _ASM_POWERPC_TLB_H
#ifdef __KERNEL__
#ifndef __powerpc64__
#include <asm/pgtable.h>
#endif
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#ifndef __powerpc64__
#include <asm/page.h>
#include <asm/mmu.h>
#endif
struct mmu_gather;
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
#if !defined(CONFIG_PPC_STD_MMU)
#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
#elif defined(__powerpc64__)
extern void pte_free_finish(void);
static inline void tlb_flush(struct mmu_gather *tlb)
{
struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch);
/* If there's a TLB batch pending, then we must flush it because the
* pages are going to be freed and we really don't want to have a CPU
* access a freed page because it has a stale TLB
*/
if (tlbbatch->index)
__flush_tlb_pending(tlbbatch);
pte_free_finish();
}
#else
extern void tlb_flush(struct mmu_gather *tlb);
#endif
/* Get the generic bits... */
#include <asm-generic/tlb.h>
#if !defined(CONFIG_PPC_STD_MMU) || defined(__powerpc64__)
#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0)
#else
extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
unsigned long address);
static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
unsigned long address)
{
if (pte_val(*ptep) & _PAGE_HASHPTE)
flush_hash_entry(tlb->mm, ptep, address);
}
#endif
#endif /* __KERNEL__ */
#endif /* __ASM_POWERPC_TLB_H */