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_save(struct task_struct *task,
  23                                struct pt_regs *regs)
  24 {
  25         if ((regs->sstatus & SR_FS) == SR_FS_DIRTY) {
  26                 __fstate_save(task);
  27                 __fstate_clean(regs);
  28         }
  29 }
  30
  31 static inline void fstate_restore(struct task_struct *task,
  32                                   struct pt_regs *regs)
  33 {
  34         if ((regs->sstatus & SR_FS) != SR_FS_OFF) {
  35                 __fstate_restore(task);
  36                 __fstate_clean(regs);
  37         }
  38 }
  39
  40 static inline void __switch_to_aux(struct task_struct *prev,
  41                                    struct task_struct *next)
  42 {
  43         struct pt_regs *regs;
  44
  45         regs = task_pt_regs(prev);
  46         if (unlikely(regs->sstatus & SR_SD))
  47                 fstate_save(prev, regs);
  48         fstate_restore(next, task_pt_regs(next));
  49 }
  50
  51 extern bool has_fpu;
  52 #else
  53 #define has_fpu false
  54 #define fstate_save(task, regs) do { } while (0)
  55 #define fstate_restore(task, regs) do { } while (0)
  56 #define __switch_to_aux(__prev, __next) do { } while (0)
  57 #endif
  58
  59 extern struct task_struct *__switch_to(struct task_struct *,
  60                                        struct task_struct *);
  61
  62 #define switch_to(prev, next, last)                     \
  63 do {                                                    \
  64         struct task_struct *__prev = (prev);            \
  65         struct task_struct *__next = (next);            \
  66         if (has_fpu)                                    \
  67                 __switch_to_aux(__prev, __next);        \
  68         ((last) = __switch_to(__prev, __next));         \
  69 } while (0)
  70
  71 #endif /* _ASM_RISCV_SWITCH_TO_H */