mirror of https://github.com/torvalds/linux.git
56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/* 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 */
|