1 files changed, 78 insertions, 0 deletions
diff --git a/arch/csky/include/asm/asid.h b/arch/csky/include/asm/asid.h
new file mode 100644
index 000000000..6ff205a97
--- /dev/null
+++ b/arch/csky/include/asm/asid.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ASM_ASID_H
+#define __ASM_ASM_ASID_H
+
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/cpumask.h>
+#include <linux/percpu.h>
+#include <linux/spinlock.h>
+
+struct asid_info
+{
+	atomic64_t	generation;
+	unsigned long	*map;
+	atomic64_t __percpu	*active;
+	u64 __percpu		*reserved;
+	u32			bits;
+	/* Lock protecting the structure */
+	raw_spinlock_t		lock;
+	/* Which CPU requires context flush on next call */
+	cpumask_t		flush_pending;
+	/* Number of ASID allocated by context (shift value) */
+	unsigned int		ctxt_shift;
+	/* Callback to locally flush the context. */
+	void			(*flush_cpu_ctxt_cb)(void);
+};
+
+#define NUM_ASIDS(info)			(1UL << ((info)->bits))
+#define NUM_CTXT_ASIDS(info)		(NUM_ASIDS(info) >> (info)->ctxt_shift)
+
+#define active_asid(info, cpu)	*per_cpu_ptr((info)->active, cpu)
+
+void asid_new_context(struct asid_info *info, atomic64_t *pasid,
+		      unsigned int cpu, struct mm_struct *mm);
+
+/*
+ * Check the ASID is still valid for the context. If not generate a new ASID.
+ *
+ * @pasid: Pointer to the current ASID batch
+ * @cpu: current CPU ID. Must have been acquired through get_cpu()
+ */
+static inline void asid_check_context(struct asid_info *info,
+				      atomic64_t *pasid, unsigned int cpu,
+				      struct mm_struct *mm)
+{
+	u64 asid, old_active_asid;
+
+	asid = atomic64_read(pasid);
+
+	/*
+	 * The memory ordering here is subtle.
+	 * If our active_asid is non-zero and the ASID matches the current
+	 * generation, then we update the active_asid entry with a relaxed
+	 * cmpxchg. Racing with a concurrent rollover means that either:
+	 *
+	 * - We get a zero back from the cmpxchg and end up waiting on the
+	 *   lock. Taking the lock synchronises with the rollover and so
+	 *   we are forced to see the updated generation.
+	 *
+	 * - We get a valid ASID back from the cmpxchg, which means the
+	 *   relaxed xchg in flush_context will treat us as reserved
+	 *   because atomic RmWs are totally ordered for a given location.
+	 */
+	old_active_asid = atomic64_read(&active_asid(info, cpu));
+	if (old_active_asid &&
+	    !((asid ^ atomic64_read(&info->generation)) >> info->bits) &&
+	    atomic64_cmpxchg_relaxed(&active_asid(info, cpu),
+				     old_active_asid, asid))
+		return;
+
+	asid_new_context(info, pasid, cpu, mm);
+}
+
+int asid_allocator_init(struct asid_info *info,
+			u32 bits, unsigned int asid_per_ctxt,
+			void (*flush_cpu_ctxt_cb)(void));
+
+#endif