Re: [PATCH 1/2] powerpc/mm/radix: Properly clear process table entry
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2017-07-10 03:51:55
Benjamin Herrenschmidt [off-list ref] writes:
On radix, the process table entry we want to clear when destroying a context is entry 0, not entry 1
.. but has no real world consequence? Or causes the system to instantly
catch fire?
I'll tag it:
Fixes: 7e381c0ff618 ("powerpc/mm/radix: Add mmu context handling callback for radix")
cheers
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index 79d8c8a..9404b5e 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c@@ -226,9 +226,15 @@ 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);