1 files changed, 139 insertions, 0 deletions
diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h
new file mode 100644
index 000000000..60e101b84
--- /dev/null
+++ b/arch/s390/include/asm/preempt.h
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_PREEMPT_H
+#define __ASM_PREEMPT_H
+
+#include <asm/current.h>
+#include <linux/thread_info.h>
+#include <asm/atomic_ops.h>
+
+#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
+
+/* We use the MSB mostly because its available */
+#define PREEMPT_NEED_RESCHED	0x80000000
+#define PREEMPT_ENABLED	(0 + PREEMPT_NEED_RESCHED)
+
+static inline int preempt_count(void)
+{
+	return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED;
+}
+
+static inline void preempt_count_set(int pc)
+{
+	int old, new;
+
+	do {
+		old = READ_ONCE(S390_lowcore.preempt_count);
+		new = (old & PREEMPT_NEED_RESCHED) |
+			(pc & ~PREEMPT_NEED_RESCHED);
+	} while (__atomic_cmpxchg(&S390_lowcore.preempt_count,
+				  old, new) != old);
+}
+
+static inline void set_preempt_need_resched(void)
+{
+	__atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
+}
+
+static inline void clear_preempt_need_resched(void)
+{
+	__atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count);
+}
+
+static inline bool test_preempt_need_resched(void)
+{
+	return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED);
+}
+
+static inline void __preempt_count_add(int val)
+{
+	/*
+	 * With some obscure config options and CONFIG_PROFILE_ALL_BRANCHES
+	 * enabled, gcc 12 fails to handle __builtin_constant_p().
+	 */
+	if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES)) {
+		if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) {
+			__atomic_add_const(val, &S390_lowcore.preempt_count);
+			return;
+		}
+	}
+	__atomic_add(val, &S390_lowcore.preempt_count);
+}
+
+static inline void __preempt_count_sub(int val)
+{
+	__preempt_count_add(-val);
+}
+
+static inline bool __preempt_count_dec_and_test(void)
+{
+	return __atomic_add(-1, &S390_lowcore.preempt_count) == 1;
+}
+
+static inline bool should_resched(int preempt_offset)
+{
+	return unlikely(READ_ONCE(S390_lowcore.preempt_count) ==
+			preempt_offset);
+}
+
+#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */
+
+#define PREEMPT_ENABLED	(0)
+
+static inline int preempt_count(void)
+{
+	return READ_ONCE(S390_lowcore.preempt_count);
+}
+
+static inline void preempt_count_set(int pc)
+{
+	S390_lowcore.preempt_count = pc;
+}
+
+static inline void set_preempt_need_resched(void)
+{
+}
+
+static inline void clear_preempt_need_resched(void)
+{
+}
+
+static inline bool test_preempt_need_resched(void)
+{
+	return false;
+}
+
+static inline void __preempt_count_add(int val)
+{
+	S390_lowcore.preempt_count += val;
+}
+
+static inline void __preempt_count_sub(int val)
+{
+	S390_lowcore.preempt_count -= val;
+}
+
+static inline bool __preempt_count_dec_and_test(void)
+{
+	return !--S390_lowcore.preempt_count && tif_need_resched();
+}
+
+static inline bool should_resched(int preempt_offset)
+{
+	return unlikely(preempt_count() == preempt_offset &&
+			tif_need_resched());
+}
+
+#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */
+
+#define init_task_preempt_count(p)	do { } while (0)
+/* Deferred to CPU bringup time */
+#define init_idle_preempt_count(p, cpu)	do { } while (0)
+
+#ifdef CONFIG_PREEMPTION
+extern asmlinkage void preempt_schedule(void);
+#define __preempt_schedule() preempt_schedule()
+extern asmlinkage void preempt_schedule_notrace(void);
+#define __preempt_schedule_notrace() preempt_schedule_notrace()
+#endif /* CONFIG_PREEMPTION */
+
+#endif /* __ASM_PREEMPT_H */