| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.12 056/196] powerpc/mm/radix: Properly clear process table entry | Date | Tue, 25 Jul 2017 12:20:55 -0700 |
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4.12-stable review patch. If anyone has any objections, please let me know.
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
commit c6bb0b8d426a8cf865ca9c8a532cc3a2927cfceb upstream.
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") 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/powerpc/mm/mmu_context_book3s64.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
--- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -223,9 +223,15 @@ void destroy_context(struct mm_struct *m 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);
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