ARC: [SMP] TLB flush
- Add mm_cpumask setting (aggregating only, unlike some other arches)
used to restrict the TLB flush cross-calling
- cross-calling versions of TLB flush routines (thanks to Noam)
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/mmu_context.h b/arch/arc/include/asm/mmu_context.h
index 45f06f5..1fd467e 100644
--- a/arch/arc/include/asm/mmu_context.h
+++ b/arch/arc/include/asm/mmu_context.h
@@ -80,7 +80,7 @@
/* move to new ASID and handle rollover */
if (unlikely(!(++asid_cpu(cpu) & MM_CTXT_ASID_MASK))) {
- flush_tlb_all();
+ local_flush_tlb_all();
/*
* Above checke for rollover of 8 bit ASID in 32 bit container.
@@ -131,6 +131,21 @@
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
+ const int cpu = smp_processor_id();
+
+ /*
+ * Note that the mm_cpumask is "aggregating" only, we don't clear it
+ * for the switched-out task, unlike some other arches.
+ * It is used to enlist cpus for sending TLB flush IPIs and not sending
+ * it to CPUs where a task once ran-on, could cause stale TLB entry
+ * re-use, specially for a multi-threaded task.
+ * e.g. T1 runs on C1, migrates to C3. T2 running on C2 munmaps.
+ * For a non-aggregating mm_cpumask, IPI not sent C1, and if T1
+ * were to re-migrate to C1, it could access the unmapped region
+ * via any existing stale TLB entries.
+ */
+ cpumask_set_cpu(cpu, mm_cpumask(next));
+
#ifndef CONFIG_SMP
/* PGD cached in MMU reg to avoid 3 mem lookups: task->mm->pgd */
write_aux_reg(ARC_REG_SCRATCH_DATA0, next->pgd);
diff --git a/arch/arc/include/asm/tlbflush.h b/arch/arc/include/asm/tlbflush.h
index b2f9bc7..71c7b2e 100644
--- a/arch/arc/include/asm/tlbflush.h
+++ b/arch/arc/include/asm/tlbflush.h
@@ -18,11 +18,18 @@
void local_flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
-/* XXX: Revisit for SMP */
+#ifndef CONFIG_SMP
#define flush_tlb_range(vma, s, e) local_flush_tlb_range(vma, s, e)
#define flush_tlb_page(vma, page) local_flush_tlb_page(vma, page)
#define flush_tlb_kernel_range(s, e) local_flush_tlb_kernel_range(s, e)
#define flush_tlb_all() local_flush_tlb_all()
#define flush_tlb_mm(mm) local_flush_tlb_mm(mm)
-
+#else
+extern void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end);
+extern void flush_tlb_page(struct vm_area_struct *vma, unsigned long page);
+extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
+extern void flush_tlb_all(void);
+extern void flush_tlb_mm(struct mm_struct *mm);
+#endif /* CONFIG_SMP */
#endif