ARC: [ASID] get_new_mmu_context() to conditionally allocate new ASID
ASID allocation changes/1
This patch does 2 things:
(1) get_new_mmu_context() NOW moves mm->ASID to a new value ONLY if it
was from a prev allocation cycle/generation OR if mm had no ASID
allocated (vs. before would unconditionally moving to a new ASID)
Callers desiring unconditional update of ASID, e.g.local_flush_tlb_mm()
(for parent's address space invalidation at fork) need to first force
the parent to an unallocated ASID.
(2) get_new_mmu_context() always sets the MMU PID reg with unchanged/new
ASID value.
The gains are:
- consolidation of all asid alloc logic into get_new_mmu_context()
- avoiding code duplication in switch_mm() for PID reg setting
- Enables future change to fold activate_mm() into switch_mm()
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index a4ad68c..b5c5e0a 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -258,13 +258,14 @@
return;
/*
- * Workaround for Android weirdism:
- * A binder VMA could end up in a task such that vma->mm != tsk->mm
- * old code would cause h/w - s/w ASID to get out of sync
+ * - Move to a new ASID, but only if the mm is still wired in
+ * (Android Binder ended up calling this for vma->mm != tsk->mm,
+ * causing h/w - s/w ASID to get out of sync)
+ * - Also get_new_mmu_context() new implementation allocates a new
+ * ASID only if it is not allocated already - so unallocate first
*/
- if (current->mm != mm)
- destroy_context(mm);
- else
+ destroy_context(mm);
+ if (current->mm == mm)
get_new_mmu_context(mm);
}