These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / arch / arm / mm / context.c

diff --git a/kernel/arch/arm/mm/context.c b/kernel/arch/arm/mm/context.c
index 845769e..c8c8b9e 100644 (file)
--- a/kernel/arch/arm/mm/context.c
+++ b/kernel/arch/arm/mm/context.c
@@ -165,13 +165,28 @@ static void flush_context(unsigned int cpu)
                __flush_icache_all();
 }
 
-static int is_reserved_asid(u64 asid)
+static bool check_update_reserved_asid(u64 asid, u64 newasid)
 {
        int cpu;
-       for_each_possible_cpu(cpu)
-               if (per_cpu(reserved_asids, cpu) == asid)
-                       return 1;
-       return 0;
+       bool hit = false;
+
+       /*
+        * Iterate over the set of reserved ASIDs looking for a match.
+        * If we find one, then we can update our mm to use newasid
+        * (i.e. the same ASID in the current generation) but we can't
+        * exit the loop early, since we need to ensure that all copies
+        * of the old ASID are updated to reflect the mm. Failure to do
+        * so could result in us missing the reserved ASID in a future
+        * generation.
+        */
+       for_each_possible_cpu(cpu) {
+               if (per_cpu(reserved_asids, cpu) == asid) {
+                       hit = true;
+                       per_cpu(reserved_asids, cpu) = newasid;
+               }
+       }
+
+       return hit;
 }
 
 static u64 new_context(struct mm_struct *mm, unsigned int cpu)
@@ -181,12 +196,14 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
        u64 generation = atomic64_read(&asid_generation);
 
        if (asid != 0) {
+               u64 newasid = generation | (asid & ~ASID_MASK);
+
                /*
                 * If our current ASID was active during a rollover, we
                 * can continue to use it and this was just a false alarm.
                 */
-               if (is_reserved_asid(asid))
-                       return generation | (asid & ~ASID_MASK);
+               if (check_update_reserved_asid(asid, newasid))
+                       return newasid;
 
                /*
                 * We had a valid ASID in a previous life, so try to re-use
@@ -194,7 +211,7 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
                 */
                asid &= ~ASID_MASK;
                if (!__test_and_set_bit(asid, asid_map))
-                       goto bump_gen;
+                       return newasid;
        }
 
        /*
@@ -216,11 +233,8 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
 
        __set_bit(asid, asid_map);
        cur_idx = asid;
-
-bump_gen:
-       asid |= generation;
        cpumask_clear(mm_cpumask(mm));
-       return asid;
+       return asid | generation;
 }
 
 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)