Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / arch / ia64 / include / asm / switch_to.h

diff --git a/kernel/arch/ia64/include/asm/switch_to.h b/kernel/arch/ia64/include/asm/switch_to.h
new file mode 100644 (file)
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--- /dev/null
+++ b/kernel/arch/ia64/include/asm/switch_to.h
@@ -0,0 +1,79 @@
+/*
+ * 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 */