Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 80 insertions, 0 deletions

diff --git a/arch/ia64/include/asm/switch_to.h b/arch/ia64/include/asm/switch_to.h
new file mode 100644
index 000000000..b10f31ec5
--- /dev/null
+++ b/arch/ia64/include/asm/switch_to.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Low-level task switching. This is based on information published in
+ * the Processor Abstraction Layer and the System Abstraction Layer
+ * manual.
+ *
+ * Copyright (C) 1998-2003 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
+ * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
+ */
+#ifndef _ASM_IA64_SWITCH_TO_H
+#define _ASM_IA64_SWITCH_TO_H
+
+#include <linux/percpu.h>
+
+struct task_struct;
+
+/*
+ * Context switch from one thread to another.  If the two threads have
+ * different address spaces, schedule() has already taken care of
+ * switching to the new address space by calling switch_mm().
+ *
+ * Disabling access to the fph partition and the debug-register
+ * context switch MUST be done before calling ia64_switch_to() since a
+ * newly created thread returns directly to
+ * ia64_ret_from_syscall_clear_r8.
+ */
+extern struct task_struct *ia64_switch_to (void *next_task);
+
+extern void ia64_save_extra (struct task_struct *task);
+extern void ia64_load_extra (struct task_struct *task);
+
+#ifdef CONFIG_PERFMON
+  DECLARE_PER_CPU(unsigned long, pfm_syst_info);
+# define PERFMON_IS_SYSWIDE() (__this_cpu_read(pfm_syst_info) & 0x1)
+#else
+# define PERFMON_IS_SYSWIDE() (0)
+#endif
+
+#define IA64_HAS_EXTRA_STATE(t)							\
+	((t)->thread.flags & (IA64_THREAD_DBG_VALID|IA64_THREAD_PM_VALID)	\
+	 || PERFMON_IS_SYSWIDE())
+
+#define __switch_to(prev,next,last) do {							 \
+	if (IA64_HAS_EXTRA_STATE(prev))								 \
+		ia64_save_extra(prev);								 \
+	if (IA64_HAS_EXTRA_STATE(next))								 \
+		ia64_load_extra(next);								 \
+	ia64_psr(task_pt_regs(next))->dfh = !ia64_is_local_fpu_owner(next);			 \
+	(last) = ia64_switch_to((next));							 \
+} while (0)
+
+#ifdef CONFIG_SMP
+/*
+ * In the SMP case, we save the fph state when context-switching away from a thread that
+ * modified fph.  This way, when the thread gets scheduled on another CPU, the CPU can
+ * pick up the state from task->thread.fph, avoiding the complication of having to fetch
+ * the latest fph state from another CPU.  In other words: eager save, lazy restore.
+ */
+# define switch_to(prev,next,last) do {						\
+	if (ia64_psr(task_pt_regs(prev))->mfh && ia64_is_local_fpu_owner(prev)) {				\
+		ia64_psr(task_pt_regs(prev))->mfh = 0;			\
+		(prev)->thread.flags |= IA64_THREAD_FPH_VALID;			\
+		__ia64_save_fpu((prev)->thread.fph);				\
+	}									\
+	__switch_to(prev, next, last);						\
+	/* "next" in old context is "current" in new context */			\
+	if (unlikely((current->thread.flags & IA64_THREAD_MIGRATION) &&	       \
+		     (task_cpu(current) !=				       \
+		      		      task_thread_info(current)->last_cpu))) { \
+		platform_migrate(current);				       \
+		task_thread_info(current)->last_cpu = task_cpu(current);       \
+	}								       \
+} while (0)
+#else
+# define switch_to(prev,next,last)	__switch_to(prev, next, last)
+#endif
+
+#endif /* _ASM_IA64_SWITCH_TO_H */