1 files changed, 15 insertions, 0 deletions

diff --git a/arch/arm/include/asm/mmu_context.h b/arch/arm/include/asm/mmu_context.h
index de6cefb329dd..a0b3cac0547c 100644
--- a/arch/arm/include/asm/mmu_context.h
+++ b/arch/arm/include/asm/mmu_context.h
@@ -43,12 +43,23 @@ void __check_kvm_seq(struct mm_struct *mm);
 #define ASID_FIRST_VERSION      (1 << ASID_BITS)
 
 extern unsigned int cpu_last_asid;
+#ifdef CONFIG_SMP
+DECLARE_PER_CPU(struct mm_struct *, current_mm);
+#endif
 
 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
 void __new_context(struct mm_struct *mm);
 
 static inline void check_context(struct mm_struct *mm)
 {
+        /*
+         * This code is executed with interrupts enabled. Therefore,
+         * mm->context.id cannot be updated to the latest ASID version
+         * on a different CPU (and condition below not triggered)
+         * without first getting an IPI to reset the context. The
+         * alternative is to take a read_lock on mm->context.id_lock
+         * (after changing its type to rwlock_t).
+         */
         if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
                 __new_context(mm);
 
@@ -108,6 +119,10 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
                 __flush_icache_all();
 #endif
         if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
+#ifdef CONFIG_SMP
+                struct mm_struct **crt_mm = &per_cpu(current_mm, cpu);
+                *crt_mm = next;
+#endif
                 check_context(next);
                 cpu_switch_mm(next->pgd, next);
                 if (cache_is_vivt())