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[PARISC] Purge existing TLB entries in set_pte_at and ptep_set_wrprotect

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This patch goes a long way toward fixing the minifail bug, and
it  significantly improves the stability of SMP machines such as
the rp3440.  When write  protecting a page for COW, we need to
purge the existing translation.  Otherwise, the COW break
doesn't occur as expected because the TLB may still have a stale entry
which allows writes.

[jejb: fix up checkpatch errors]
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
John David Anglin
2013-01-14 19:45:00 -05:00
committed by James Bottomley
parent 5da1f88b8b
commit 7139bc1579
2 changed files with 28 additions and 3 deletions
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13
arch/parisc/include/asm/pgtable.h
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@@ -12,11 +12,10 @@
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/mm_types.h>
#include <asm/processor.h>
#include <asm/cache.h>
struct vm_area_struct;
/*
* kern_addr_valid(ADDR) tests if ADDR is pointing to valid kernel
* memory. For the return value to be meaningful, ADDR must be >=
@@ -40,7 +39,14 @@ struct vm_area_struct;
do{ \
*(pteptr) = (pteval); \
} while(0)
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
extern void purge_tlb_entries(struct mm_struct *, unsigned long);
#define set_pte_at(mm, addr, ptep, pteval) \
do { \
set_pte(ptep, pteval); \
purge_tlb_entries(mm, addr); \
} while (0)
#endif /* !__ASSEMBLY__ */
@@ -466,6 +472,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
old = pte_val(*ptep);
new = pte_val(pte_wrprotect(__pte (old)));
} while (cmpxchg((unsigned long *) ptep, old, new) != old);
purge_tlb_entries(mm, addr);
#else
pte_t old_pte = *ptep;
set_pte_at(mm, addr, ptep, pte_wrprotect(old_pte));