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powerpc/mm/radix: Properly clear process table entry

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On radix, the process table entry we want to clear when destroying a
context is entry 0, not entry 1. This has no *immediate* consequence
on Power9, but it can cause other bugs to become worse.

Fixes: 7e381c0ff618 ("powerpc/mm/radix: Add mmu context handling callback for radix")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Benjamin Herrenschmidt 2017-07-08 07:45:32 -05:00 committed by Michael Ellerman
parent 1c0eaf0f56
commit c6bb0b8d42
1 changed files with 9 additions and 3 deletions
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12
arch/powerpc/mm/mmu_context_book3s64.c
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@ -223,9 +223,15 @@ void destroy_context(struct mm_struct *mm)
mm->context.cop_lockp = NULL;
#endif /* CONFIG_PPC_ICSWX */
if (radix_enabled())
process_tb[mm->context.id].prtb1 = 0;
else
if (radix_enabled()) {
/*
* Radix doesn't have a valid bit in the process table
* entries. However we know that at least P9 implementation
* will avoid caching an entry with an invalid RTS field,
* and 0 is invalid. So this will do.
*/
process_tb[mm->context.id].prtb0 = 0;
} else
subpage_prot_free(mm);
destroy_pagetable_page(mm);
__destroy_context(mm->context.id);