arch/riscv/include/asm/switch_to.h

   1 /*
   2  * Copyright (C) 2012 Regents of the University of California
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful,
   9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  *   GNU General Public License for more details.
  12  */
  13
  14 #ifndef _ASM_RISCV_SWITCH_TO_H
  15 #define _ASM_RISCV_SWITCH_TO_H
  16
  17 #include <asm/processor.h>
  18 #include <asm/ptrace.h>
  19 #include <asm/csr.h>
  20
  21 #ifdef CONFIG_FPU
  22 extern void __fstate_save(struct task_struct *save_to);
  23 extern void __fstate_restore(struct task_struct *restore_from);
  24
  25 static inline void __fstate_clean(struct pt_regs *regs)
  26 {
  27         regs->sstatus |= (regs->sstatus & ~(SR_FS)) | SR_FS_CLEAN;
  28 }
  29
  30 static inline void fstate_save(struct task_struct *task,
  31                                struct pt_regs *regs)
  32 {
  33         if ((regs->sstatus & SR_FS) == SR_FS_DIRTY) {
  34                 __fstate_save(task);
  35                 __fstate_clean(regs);
  36         }
  37 }
  38
  39 static inline void fstate_restore(struct task_struct *task,
  40                                   struct pt_regs *regs)
  41 {
  42         if ((regs->sstatus & SR_FS) != SR_FS_OFF) {
  43                 __fstate_restore(task);
  44                 __fstate_clean(regs);
  45         }
  46 }
  47
  48 static inline void __switch_to_aux(struct task_struct *prev,
  49                                    struct task_struct *next)
  50 {
  51         struct pt_regs *regs;
  52
  53         regs = task_pt_regs(prev);
  54         if (unlikely(regs->sstatus & SR_SD))
  55                 fstate_save(prev, regs);
  56         fstate_restore(next, task_pt_regs(next));
  57 }
  58
  59 extern bool has_fpu;
  60 #else
  61 #define has_fpu false
  62 #define fstate_save(task, regs) do { } while (0)
  63 #define fstate_restore(task, regs) do { } while (0)
  64 #define __switch_to_aux(__prev, __next) do { } while (0)
  65 #endif
  66
  67 extern struct task_struct *__switch_to(struct task_struct *,
  68                                        struct task_struct *);
  69
  70 #define switch_to(prev, next, last)                     \
  71 do {                                                    \
  72         struct task_struct *__prev = (prev);            \
  73         struct task_struct *__next = (next);            \
  74         if (has_fpu)                                    \
  75                 __switch_to_aux(__prev, __next);        \
  76         ((last) = __switch_to(__prev, __next));         \
  77 } while (0)
  78
  79 #endif /* _ASM_RISCV_SWITCH_TO_H */