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/hwcap.h>
  12 #include <asm/processor.h>
  13 #include <asm/ptrace.h>
  14 #include <asm/csr.h>
  15
  16 #ifdef CONFIG_FPU
  17 extern void __fstate_save(struct task_struct *save_to);
  18 extern void __fstate_restore(struct task_struct *restore_from);
  19
  20 static inline void __fstate_clean(struct pt_regs *regs)
  21 {
  22         regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
  23 }
  24
  25 static inline void fstate_off(struct task_struct *task,
  26                               struct pt_regs *regs)
  27 {
  28         regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
  29 }
  30
  31 static inline void fstate_save(struct task_struct *task,
  32                                struct pt_regs *regs)
  33 {
  34         if ((regs->status & SR_FS) == SR_FS_DIRTY) {
  35                 __fstate_save(task);
  36                 __fstate_clean(regs);
  37         }
  38 }
  39
  40 static inline void fstate_restore(struct task_struct *task,
  41                                   struct pt_regs *regs)
  42 {
  43         if ((regs->status & SR_FS) != SR_FS_OFF) {
  44                 __fstate_restore(task);
  45                 __fstate_clean(regs);
  46         }
  47 }
  48
  49 static inline void __switch_to_aux(struct task_struct *prev,
  50                                    struct task_struct *next)
  51 {
  52         struct pt_regs *regs;
  53
  54         regs = task_pt_regs(prev);
  55         if (unlikely(regs->status & SR_SD))
  56                 fstate_save(prev, regs);
  57         fstate_restore(next, task_pt_regs(next));
  58 }
  59
  60 static __always_inline bool has_fpu(void)
  61 {
  62         return static_branch_likely(&riscv_isa_ext_keys[RISCV_ISA_EXT_KEY_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 */