Commit c6bb0b8d authored Jul 08, 2017 by Benjamin Herrenschmidt Committed by Michael Ellerman Jul 10, 2017

powerpc/mm/radix: Properly clear process table entry



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: 7e381c0f ("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>

parent 1c0eaf0f

arch/powerpc/mm/mmu_context_book3s64.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -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);