arch/riscv/include/asm/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/sched/task_stack.h>
  10 #include <asm/processor.h>
  11 #include <asm/ptrace.h>
  12 #include <asm/csr.h>
  13
  14 #ifdef CONFIG_FPU
  15 extern void __fstate_save(struct task_struct *save_to);
  16 extern void __fstate_restore(struct task_struct *restore_from);
  17
  18 static inline void __fstate_clean(struct pt_regs *regs)
  19 {
  20         regs->sstatus = (regs->sstatus & ~SR_FS) | SR_FS_CLEAN;
  21 }
  22
  23 static inline void fstate_off(struct task_struct *task,
  24                               struct pt_regs *regs)
  25 {
  26         regs->sstatus = (regs->sstatus & ~SR_FS) | SR_FS_OFF;
  27 }
  28
  29 static inline void fstate_save(struct task_struct *task,
  30                                struct pt_regs *regs)
  31 {
  32         if ((regs->sstatus & SR_FS) == SR_FS_DIRTY) {
  33                 __fstate_save(task);
  34                 __fstate_clean(regs);
  35         }
  36 }
  37
  38 static inline void fstate_restore(struct task_struct *task,
  39                                   struct pt_regs *regs)
  40 {
  41         if ((regs->sstatus & SR_FS) != SR_FS_OFF) {
  42                 __fstate_restore(task);
  43                 __fstate_clean(regs);
  44         }
  45 }
  46
  47 static inline void __switch_to_aux(struct task_struct *prev,
  48                                    struct task_struct *next)
  49 {
  50         struct pt_regs *regs;
  51
  52         regs = task_pt_regs(prev);
  53         if (unlikely(regs->sstatus & SR_SD))
  54                 fstate_save(prev, regs);
  55         fstate_restore(next, task_pt_regs(next));
  56 }
  57
  58 extern bool has_fpu;
  59 #else
  60 #define has_fpu false
  61 #define fstate_save(task, regs) do { } while (0)
  62 #define fstate_restore(task, regs) do { } while (0)
  63 #define __switch_to_aux(__prev, __next) do { } while (0)
  64 #endif
  65
  66 extern struct task_struct *__switch_to(struct task_struct *,
  67                                        struct task_struct *);
  68
  69 #define switch_to(prev, next, last)                     \
  70 do {                                                    \
  71         struct task_struct *__prev = (prev);            \
  72         struct task_struct *__next = (next);            \
  73         if (has_fpu)                                    \
  74                 __switch_to_aux(__prev, __next);        \
  75         ((last) = __switch_to(__prev, __next));         \
  76 } while (0)
  77
  78 #endif /* _ASM_RISCV_SWITCH_TO_H */