lbt.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Author: Qi Hu <huqi@loongson.cn>
  4 *         Huacai Chen <chenhuacai@loongson.cn>
  5 * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
  6 */
  7#ifndef _ASM_LBT_H
  8#define _ASM_LBT_H
  9
 10#include <asm/cpu.h>
 11#include <asm/current.h>
 12#include <asm/loongarch.h>
 13#include <asm/processor.h>
 14
 15asmlinkage void _init_lbt(void);
 16asmlinkage void _save_lbt(struct loongarch_lbt *);
 17asmlinkage void _restore_lbt(struct loongarch_lbt *);
 18asmlinkage int _save_lbt_context(void __user *regs, void __user *eflags);
 19asmlinkage int _restore_lbt_context(void __user *regs, void __user *eflags);
 20asmlinkage int _save_ftop_context(void __user *ftop);
 21asmlinkage int _restore_ftop_context(void __user *ftop);
 22
 23static inline int is_lbt_enabled(void)
 24{
 25	if (!cpu_has_lbt)
 26		return 0;
 27
 28	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_LBTEN) ?
 29		1 : 0;
 30}
 31
 32static inline int is_lbt_owner(void)
 33{
 34	return test_thread_flag(TIF_USEDLBT);
 35}
 36
 37#ifdef CONFIG_CPU_HAS_LBT
 38
 39static inline void enable_lbt(void)
 40{
 41	if (cpu_has_lbt)
 42		csr_xchg32(CSR_EUEN_LBTEN, CSR_EUEN_LBTEN, LOONGARCH_CSR_EUEN);
 43}
 44
 45static inline void disable_lbt(void)
 46{
 47	if (cpu_has_lbt)
 48		csr_xchg32(0, CSR_EUEN_LBTEN, LOONGARCH_CSR_EUEN);
 49}
 50
 51static inline void __own_lbt(void)
 52{
 53	enable_lbt();
 54	set_thread_flag(TIF_USEDLBT);
 55	KSTK_EUEN(current) |= CSR_EUEN_LBTEN;
 56}
 57
 58static inline void own_lbt_inatomic(int restore)
 59{
 60	if (cpu_has_lbt && !is_lbt_owner()) {
 61		__own_lbt();
 62		if (restore)
 63			_restore_lbt(&current->thread.lbt);
 64	}
 65}
 66
 67static inline void own_lbt(int restore)
 68{
 69	preempt_disable();
 70	own_lbt_inatomic(restore);
 71	preempt_enable();
 72}
 73
 74static inline void lose_lbt_inatomic(int save, struct task_struct *tsk)
 75{
 76	if (cpu_has_lbt && is_lbt_owner()) {
 77		if (save)
 78			_save_lbt(&tsk->thread.lbt);
 79
 80		disable_lbt();
 81		clear_tsk_thread_flag(tsk, TIF_USEDLBT);
 82	}
 83	KSTK_EUEN(tsk) &= ~(CSR_EUEN_LBTEN);
 84}
 85
 86static inline void lose_lbt(int save)
 87{
 88	preempt_disable();
 89	lose_lbt_inatomic(save, current);
 90	preempt_enable();
 91}
 92
 93static inline void init_lbt(void)
 94{
 95	__own_lbt();
 96	_init_lbt();
 97}
 98#else
 99static inline void own_lbt_inatomic(int restore) {}
100static inline void lose_lbt_inatomic(int save, struct task_struct *tsk) {}
101static inline void init_lbt(void) {}
102static inline void lose_lbt(int save) {}
103#endif
104
105static inline int thread_lbt_context_live(void)
106{
107	if (!cpu_has_lbt)
108		return 0;
109
110	return test_thread_flag(TIF_LBT_CTX_LIVE);
111}
112
113#endif /* _ASM_LBT_H */