From: Benjamin Herrenschmidt Date: Fri, 7 Jul 2017 21:12:16 +0000 (-0500) Subject: powerpc/mm/radix: Synchronize updates to the process table X-Git-Tag: v4.13-rc1~21^2~7 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3a6a04706fd08eb5677fdfc086e26fcd5eb154f4;p=platform%2Fkernel%2Flinux-exynos.git powerpc/mm/radix: Synchronize updates to the process table When writing to the process table, we need to ensure the store is visible to a subsequent access by the MMU. We assume we never have the PID active while doing the update, so a ptesync/isync pair should hopefully be a big enough hammer for our purpose. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index ceff762..abed1fe 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -138,6 +138,14 @@ static int radix__init_new_context(struct mm_struct *mm) rts_field = radix__get_tree_size(); process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE); + /* + * Order the above store with subsequent update of the PID + * register (at which point HW can start loading/caching + * the entry) and the corresponding load by the MMU from + * the L2 cache. + */ + asm volatile("ptesync;isync" : : : "memory"); + mm->context.npu_context = NULL; return index;