1 files changed, 55 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h
new file mode 100644
index 000000000000..89004f4ca208
--- /dev/null
+++ b/arch/x86/include/asm/fpu/sched.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_FPU_SCHED_H
+#define _ASM_X86_FPU_SCHED_H
+
+#include <linux/sched.h>
+
+#include <asm/cpufeature.h>
+#include <asm/fpu/types.h>
+
+#include <asm/trace/fpu.h>
+
+extern void save_fpregs_to_fpstate(struct fpu *fpu);
+extern void fpu__drop(struct task_struct *tsk);
+extern int  fpu_clone(struct task_struct *dst, u64 clone_flags, bool minimal,
+		      unsigned long shstk_addr);
+extern void fpu_flush_thread(void);
+
+/*
+ * FPU state switching for scheduling.
+ *
+ * switch_fpu() saves the old state and sets TIF_NEED_FPU_LOAD if
+ * TIF_NEED_FPU_LOAD is not set.  This is done within the context
+ * of the old process.
+ *
+ * Once TIF_NEED_FPU_LOAD is set, it is required to load the
+ * registers before returning to userland or using the content
+ * otherwise.
+ *
+ * The FPU context is only stored/restored for a user task and
+ * PF_KTHREAD is used to distinguish between kernel and user threads.
+ */
+static inline void switch_fpu(struct task_struct *old, int cpu)
+{
+	if (!test_tsk_thread_flag(old, TIF_NEED_FPU_LOAD) &&
+	    cpu_feature_enabled(X86_FEATURE_FPU) &&
+	    !(old->flags & (PF_KTHREAD | PF_USER_WORKER))) {
+		struct fpu *old_fpu = x86_task_fpu(old);
+
+		set_tsk_thread_flag(old, TIF_NEED_FPU_LOAD);
+		save_fpregs_to_fpstate(old_fpu);
+		/*
+		 * The save operation preserved register state, so the
+		 * fpu_fpregs_owner_ctx is still @old_fpu. Store the
+		 * current CPU number in @old_fpu, so the next return
+		 * to user space can avoid the FPU register restore
+		 * when is returns on the same CPU and still owns the
+		 * context. See fpregs_restore_userregs().
+		 */
+		old_fpu->last_cpu = cpu;
+
+		trace_x86_fpu_regs_deactivated(old_fpu);
+	}
+}
+
+#endif /* _ASM_X86_FPU_SCHED_H */