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-rw-r--r--arch/arm64/mm/context.c54
1 files changed, 41 insertions, 13 deletions
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index e87f53ff5f58..c90c3c5f46af 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -24,6 +24,7 @@
#include <asm/cpufeature.h>
#include <asm/mmu_context.h>
+#include <asm/smp.h>
#include <asm/tlbflush.h>
static u32 asid_bits;
@@ -40,6 +41,45 @@ 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_unsigned_field(read_cpuid(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;
+}
+
+/* Check if the current cpu's ASIDBits is compatible with asid_bits */
+void verify_cpu_asid_bits(void)
+{
+ u32 asid = get_cpu_asid_bits();
+
+ if (asid < asid_bits) {
+ /*
+ * We cannot decrease the ASID size at runtime, so panic if we support
+ * fewer ASID bits than the boot CPU.
+ */
+ pr_crit("CPU%d: smaller ASID size(%u) than boot CPU (%u)\n",
+ smp_processor_id(), asid, asid_bits);
+ update_cpu_boot_status(CPU_PANIC_KERNEL);
+ cpu_park_loop();
+ }
+}
+
static void flush_context(unsigned int cpu)
{
int i;
@@ -187,19 +227,7 @@ switch_mm_fastpath:
static int asids_init(void)
{
- int fld = cpuid_feature_extract_field(read_cpuid(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);