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/jump_label.h>
  10 #include <linux/sched/task_stack.h>
  11 #include <asm/processor.h>
  12 #include <asm/ptrace.h>
  13 #include <asm/csr.h>
  14
  15 #ifdef CONFIG_FPU
  16 extern void __fstate_save(struct task_struct *save_to);
  17 extern void __fstate_restore(struct task_struct *restore_from);
  18
  19 static inline void __fstate_clean(struct pt_regs *regs)
  20 {
  21         regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
  22 }
  23
  24 static inline void fstate_off(struct task_struct *task,
  25                               struct pt_regs *regs)
  26 {
  27         regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
  28 }
  29
  30 static inline void fstate_save(struct task_struct *task,
  31                                struct pt_regs *regs)
  32 {
  33         if ((regs->status & 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->status & 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->status & SR_SD))
  55                 fstate_save(prev, regs);
  56         fstate_restore(next, task_pt_regs(next));
  57 }
  58
  59 extern struct static_key_false cpu_hwcap_fpu;
  60 static __always_inline bool has_fpu(void)
  61 {
  62         return static_branch_likely(&cpu_hwcap_fpu);
  63 }
  64 #else
  65 static __always_inline bool has_fpu(void) { return false; }
  66 #define fstate_save(task, regs) do { } while (0)
  67 #define fstate_restore(task, regs) do { } while (0)
  68 #define __switch_to_aux(__prev, __next) do { } while (0)
  69 #endif
  70
  71 extern struct task_struct *__switch_to(struct task_struct *,
  72                                        struct task_struct *);
  73
  74 #define switch_to(prev, next, last)                     \
  75 do {                                                    \
  76         struct task_struct *__prev = (prev);            \
  77         struct task_struct *__next = (next);            \
  78         if (has_fpu())                                  \
  79                 __switch_to_aux(__prev, __next);        \
  80         ((last) = __switch_to(__prev, __next));         \
  81 } while (0)
  82
  83 #endif /* _ASM_RISCV_SWITCH_TO_H */