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arm64: mm: Correct show_pte behaviour 

show_pte makes use of the *_none_or_clear_bad style functions. If a
pgd, pud or pmd is identified as being bad, it will then be cleared.

As show_pte appears to be called from either the user or kernel
fault handlers this side effect can lead to unpredictable behaviour;
especially as TLB entries are not invalidated.

This patch removes the page table sanitisation from show_pte. If a
bad pgd, pud or pmd is encountered it is left unmodified.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Steve Capper 2013-04-19 15:49:31 +01:00 committed by Catalin Marinas
parent f15a2a12d0
commit 4339e3f389
1 changed files with 3 additions and 3 deletions
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6
arch/arm64/mm/fault.c
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@ -57,16 +57,16 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
pmd_t *pmd;
pte_t *pte;
if (pgd_none_or_clear_bad(pgd))
if (pgd_none(*pgd) || pgd_bad(*pgd))
break;
pud = pud_offset(pgd, addr);
if (pud_none_or_clear_bad(pud))
if (pud_none(*pud) || pud_bad(*pud))
break;
pmd = pmd_offset(pud, addr);
printk(", *pmd=%016llx", pmd_val(*pmd));
if (pmd_none_or_clear_bad(pmd))
if (pmd_none(*pmd) || pmd_bad(*pmd))
break;
pte = pte_offset_map(pmd, addr);