switch_to.h

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Copyright (C) 2012 Regents of the University of California
  4 */
  5
  6#ifndef _ASM_RISCV_SWITCH_TO_H
  7#define _ASM_RISCV_SWITCH_TO_H
  8
  9#include <linux/jump_label.h>
 10#include <linux/sched/task_stack.h>
 11#include <linux/mm_types.h>
 12#include <asm/vector.h>
 13#include <asm/cpufeature.h>
 14#include <asm/processor.h>
 15#include <asm/ptrace.h>
 16#include <asm/csr.h>
 17
 18#ifdef CONFIG_FPU
 19extern void __fstate_save(struct task_struct *save_to);
 20extern void __fstate_restore(struct task_struct *restore_from);
 21
 22static inline void __fstate_clean(struct pt_regs *regs)
 23{
 24	regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
 25}
 26
 27static inline void fstate_off(struct task_struct *task,
 28			      struct pt_regs *regs)
 29{
 30	regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
 31}
 32
 33static inline void fstate_save(struct task_struct *task,
 34			       struct pt_regs *regs)
 35{
 36	if ((regs->status & SR_FS) == SR_FS_DIRTY) {
 37		__fstate_save(task);
 38		__fstate_clean(regs);
 39	}
 40}
 41
 42static inline void fstate_restore(struct task_struct *task,
 43				  struct pt_regs *regs)
 44{
 45	if ((regs->status & SR_FS) != SR_FS_OFF) {
 46		__fstate_restore(task);
 47		__fstate_clean(regs);
 48	}
 49}
 50
 51static inline void __switch_to_fpu(struct task_struct *prev,
 52				   struct task_struct *next)
 53{
 54	struct pt_regs *regs;
 55
 56	regs = task_pt_regs(prev);
 57	fstate_save(prev, regs);
 58	fstate_restore(next, task_pt_regs(next));
 59}
 60
 61static __always_inline bool has_fpu(void)
 62{
 63	return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
 64		riscv_has_extension_likely(RISCV_ISA_EXT_d);
 65}
 66#else
 67static __always_inline bool has_fpu(void) { return false; }
 68#define fstate_save(task, regs) do { } while (0)
 69#define fstate_restore(task, regs) do { } while (0)
 70#define __switch_to_fpu(__prev, __next) do { } while (0)
 71#endif
 72
 73static inline void envcfg_update_bits(struct task_struct *task,
 74				      unsigned long mask, unsigned long val)
 75{
 76	unsigned long envcfg;
 77
 78	envcfg = (task->thread.envcfg & ~mask) | val;
 79	task->thread.envcfg = envcfg;
 80	if (task == current)
 81		csr_write(CSR_ENVCFG, envcfg);
 82}
 83
 84static inline void __switch_to_envcfg(struct task_struct *next)
 85{
 86	asm volatile (ALTERNATIVE("nop", "csrw " __stringify(CSR_ENVCFG) ", %0",
 87				  0, RISCV_ISA_EXT_XLINUXENVCFG, 1)
 88			:: "r" (next->thread.envcfg) : "memory");
 89}
 90
 91extern struct task_struct *__switch_to(struct task_struct *,
 92				       struct task_struct *);
 93
 94static inline bool switch_to_should_flush_icache(struct task_struct *task)
 95{
 96#ifdef CONFIG_SMP
 97	bool stale_mm = task->mm && task->mm->context.force_icache_flush;
 98	bool stale_thread = task->thread.force_icache_flush;
 99	bool thread_migrated = smp_processor_id() != task->thread.prev_cpu;
100
101	return thread_migrated && (stale_mm || stale_thread);
102#else
103	return false;
104#endif
105}
106
107#ifdef CONFIG_SMP
108#define __set_prev_cpu(thread) ((thread).prev_cpu = smp_processor_id())
109#else
110#define __set_prev_cpu(thread)
111#endif
112
113#define switch_to(prev, next, last)			\
114do {							\
115	struct task_struct *__prev = (prev);		\
116	struct task_struct *__next = (next);		\
117	__set_prev_cpu(__prev->thread);			\
118	if (has_fpu())					\
119		__switch_to_fpu(__prev, __next);	\
120	if (has_vector() || has_xtheadvector())		\
121		__switch_to_vector(__prev, __next);	\
122	if (switch_to_should_flush_icache(__next))	\
123		local_flush_icache_all();		\
124	__switch_to_envcfg(__next);			\
125	((last) = __switch_to(__prev, __next));		\
126} while (0)
127
128#endif /* _ASM_RISCV_SWITCH_TO_H */