37a7a2a10e
The has_fpu check sits at hot code path: switch_to(). Currently, has_fpu is a bool variable if FPU=y, switch_to() checks it each time, we can optimize out this check by turning the has_fpu into a static key. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
84 lines
2.1 KiB
C
84 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* Copyright (C) 2012 Regents of the University of California
|
|
*/
|
|
|
|
#ifndef _ASM_RISCV_SWITCH_TO_H
|
|
#define _ASM_RISCV_SWITCH_TO_H
|
|
|
|
#include <linux/jump_label.h>
|
|
#include <linux/sched/task_stack.h>
|
|
#include <asm/processor.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/csr.h>
|
|
|
|
#ifdef CONFIG_FPU
|
|
extern void __fstate_save(struct task_struct *save_to);
|
|
extern void __fstate_restore(struct task_struct *restore_from);
|
|
|
|
static inline void __fstate_clean(struct pt_regs *regs)
|
|
{
|
|
regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
|
|
}
|
|
|
|
static inline void fstate_off(struct task_struct *task,
|
|
struct pt_regs *regs)
|
|
{
|
|
regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
|
|
}
|
|
|
|
static inline void fstate_save(struct task_struct *task,
|
|
struct pt_regs *regs)
|
|
{
|
|
if ((regs->status & SR_FS) == SR_FS_DIRTY) {
|
|
__fstate_save(task);
|
|
__fstate_clean(regs);
|
|
}
|
|
}
|
|
|
|
static inline void fstate_restore(struct task_struct *task,
|
|
struct pt_regs *regs)
|
|
{
|
|
if ((regs->status & SR_FS) != SR_FS_OFF) {
|
|
__fstate_restore(task);
|
|
__fstate_clean(regs);
|
|
}
|
|
}
|
|
|
|
static inline void __switch_to_aux(struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
struct pt_regs *regs;
|
|
|
|
regs = task_pt_regs(prev);
|
|
if (unlikely(regs->status & SR_SD))
|
|
fstate_save(prev, regs);
|
|
fstate_restore(next, task_pt_regs(next));
|
|
}
|
|
|
|
extern struct static_key_false cpu_hwcap_fpu;
|
|
static __always_inline bool has_fpu(void)
|
|
{
|
|
return static_branch_likely(&cpu_hwcap_fpu);
|
|
}
|
|
#else
|
|
static __always_inline bool has_fpu(void) { return false; }
|
|
#define fstate_save(task, regs) do { } while (0)
|
|
#define fstate_restore(task, regs) do { } while (0)
|
|
#define __switch_to_aux(__prev, __next) do { } while (0)
|
|
#endif
|
|
|
|
extern struct task_struct *__switch_to(struct task_struct *,
|
|
struct task_struct *);
|
|
|
|
#define switch_to(prev, next, last) \
|
|
do { \
|
|
struct task_struct *__prev = (prev); \
|
|
struct task_struct *__next = (next); \
|
|
if (has_fpu()) \
|
|
__switch_to_aux(__prev, __next); \
|
|
((last) = __switch_to(__prev, __next)); \
|
|
} while (0)
|
|
|
|
#endif /* _ASM_RISCV_SWITCH_TO_H */
|