arm64: Add helper for extracting ASIDBits

Add a helper to extract ASIDBits on the current cpu

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 7275628..21f9f1e 100644 (file)
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -40,6 +40,28 @@ static cpumask_t tlb_flush_pending;
 #define ASID_FIRST_VERSION     (1UL << asid_bits)
 #define NUM_USER_ASIDS         ASID_FIRST_VERSION
 
+/* Get the ASIDBits supported by the current CPU */
+static u32 get_cpu_asid_bits(void)
+{
+       u32 asid;
+       int fld = cpuid_feature_extract_field(read_cpuid(SYS_ID_AA64MMFR0_EL1),
+                                               ID_AA64MMFR0_ASID_SHIFT);
+
+       switch (fld) {
+       default:
+               pr_warn("CPU%d: Unknown ASID size (%d); assuming 8-bit\n",
+                                       smp_processor_id(),  fld);
+               /* Fallthrough */
+       case 0:
+               asid = 8;
+               break;
+       case 2:
+               asid = 16;
+       }
+
+       return asid;
+}
+
 static void flush_context(unsigned int cpu)
 {
        int i;
@@ -187,19 +209,7 @@ switch_mm_fastpath:
 
 static int asids_init(void)
 {
-       int fld = cpuid_feature_extract_field(read_cpuid(SYS_ID_AA64MMFR0_EL1), 4);
-
-       switch (fld) {
-       default:
-               pr_warn("Unknown ASID size (%d); assuming 8-bit\n", fld);
-               /* Fallthrough */
-       case 0:
-               asid_bits = 8;
-               break;
-       case 2:
-               asid_bits = 16;
-       }
-
+       asid_bits = get_cpu_asid_bits();
        /* If we end up with more CPUs than ASIDs, expect things to crash */
        WARN_ON(NUM_USER_ASIDS < num_possible_cpus());
        atomic64_set(&asid_generation, ASID_FIRST_VERSION);