mirror of
https://github.com/torvalds/linux.git
synced 2025-12-01 07:26:02 +07:00
e3bfa38599
This will make the removal of the task_struct::thread.fpu array easier. No change in functionality - code generated before and after this commit is identical on x86-defconfig: kepler:~/tip> diff -up vmlinux.before.asm vmlinux.after.asm kepler:~/tip> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chang S. Bae <chang.seok.bae@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20250409211127.3544993-3-mingo@kernel.org
72 lines
2.2 KiB
C
72 lines
2.2 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 fpu *fpu);
|
|
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.
|
|
*
|
|
* This is a two-stage process:
|
|
*
|
|
* - switch_fpu_prepare() saves the old state.
|
|
* This is done within the context of the old process.
|
|
*
|
|
* - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
|
|
* will get loaded on return to userspace, or when the kernel needs it.
|
|
*
|
|
* If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
|
|
* are saved in the current thread's FPU register state.
|
|
*
|
|
* If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
|
|
* hold current()'s FPU registers. 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_prepare(struct task_struct *old, int cpu)
|
|
{
|
|
if (cpu_feature_enabled(X86_FEATURE_FPU) &&
|
|
!(old->flags & (PF_KTHREAD | PF_USER_WORKER))) {
|
|
struct fpu *old_fpu = x86_task_fpu(old);
|
|
|
|
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.
|
|
*/
|
|
old_fpu->last_cpu = cpu;
|
|
|
|
trace_x86_fpu_regs_deactivated(old_fpu);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Delay loading of the complete FPU state until the return to userland.
|
|
* PKRU is handled separately.
|
|
*/
|
|
static inline void switch_fpu_finish(struct task_struct *new)
|
|
{
|
|
if (cpu_feature_enabled(X86_FEATURE_FPU))
|
|
set_tsk_thread_flag(new, TIF_NEED_FPU_LOAD);
|
|
}
|
|
|
|
#endif /* _ASM_X86_FPU_SCHED_H */
|