mirror of https://gitee.com/openkylin/linux.git
80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
/*
|
|
* 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() (__get_cpu_var(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 */
|