From: Benjamin Herrenschmidt Date: Sat, 8 Jul 2017 12:45:32 +0000 (-0500) Subject: powerpc/mm/radix: Properly clear process table entry X-Git-Tag: v4.12.4~143 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=27444f6571cd391ea37bd543e077bdf29f35cf07;p=thirdparty%2Fkernel%2Fstable.git powerpc/mm/radix: Properly clear process table entry 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 Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index a3edf813d4556..51303f8af015b 100644 --- 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 *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);