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/* 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, unsigned long 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 */
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