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