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 <linux/mm_types.h>
  12 #include <asm/vector.h>
  13 #include <asm/cpufeature.h>
  14 #include <asm/processor.h>
  15 #include <asm/ptrace.h>
  16 #include <asm/csr.h>
  17
  18 #ifdef CONFIG_FPU
  19 extern void __fstate_save(struct task_struct *save_to);
  20 extern void __fstate_restore(struct task_struct *restore_from);
  21
  22 static inline void __fstate_clean(struct pt_regs *regs)
  23 {
  24         regs->status = (regs->status & ~SR_FS) | SR_FS_CLEAN;
  25 }
  26
  27 static inline void fstate_off(struct task_struct *task,
  28                               struct pt_regs *regs)
  29 {
  30         regs->status = (regs->status & ~SR_FS) | SR_FS_OFF;
  31 }
  32
  33 static inline void fstate_save(struct task_struct *task,
  34                                struct pt_regs *regs)
  35 {
  36         if ((regs->status & SR_FS) == SR_FS_DIRTY) {
  37                 __fstate_save(task);
  38                 __fstate_clean(regs);
  39         }
  40 }
  41
  42 static inline void fstate_restore(struct task_struct *task,
  43                                   struct pt_regs *regs)
  44 {
  45         if ((regs->status & SR_FS) != SR_FS_OFF) {
  46                 __fstate_restore(task);
  47                 __fstate_clean(regs);
  48         }
  49 }
  50
  51 static inline void __switch_to_fpu(struct task_struct *prev,
  52                                    struct task_struct *next)
  53 {
  54         struct pt_regs *regs;
  55
  56         regs = task_pt_regs(prev);
  57         fstate_save(prev, regs);
  58         fstate_restore(next, task_pt_regs(next));
  59 }
  60
  61 static __always_inline bool has_fpu(void)
  62 {
  63         return riscv_has_extension_likely(RISCV_ISA_EXT_f) ||
  64                 riscv_has_extension_likely(RISCV_ISA_EXT_d);
  65 }
  66 #else
  67 static __always_inline bool has_fpu(void) { return false; }
  68 #define fstate_save(task, regs) do { } while (0)
  69 #define fstate_restore(task, regs) do { } while (0)
  70 #define __switch_to_fpu(__prev, __next) do { } while (0)
  71 #endif
  72
  73 static inline void envcfg_update_bits(struct task_struct *task,
  74                                       unsigned long mask, unsigned long val)
  75 {
  76         unsigned long envcfg;
  77
  78         envcfg = (task->thread.envcfg & ~mask) | val;
  79         task->thread.envcfg = envcfg;
  80         if (task == current)
  81                 csr_write(CSR_ENVCFG, envcfg);
  82 }
  83
  84 static inline void __switch_to_envcfg(struct task_struct *next)
  85 {
  86         asm volatile (ALTERNATIVE("nop", "csrw " __stringify(CSR_ENVCFG) ", %0",
  87                                   0, RISCV_ISA_EXT_XLINUXENVCFG, 1)
  88                         :: "r" (next->thread.envcfg) : "memory");
  89 }
  90
  91 extern struct task_struct *__switch_to(struct task_struct *,
  92                                        struct task_struct *);
  93
  94 static inline bool switch_to_should_flush_icache(struct task_struct *task)
  95 {
  96 #ifdef CONFIG_SMP
  97         bool stale_mm = task->mm && task->mm->context.force_icache_flush;
  98         bool stale_thread = task->thread.force_icache_flush;
  99         bool thread_migrated = smp_processor_id() != task->thread.prev_cpu;
 100
 101         return thread_migrated && (stale_mm || stale_thread);
 102 #else
 103         return false;
 104 #endif
 105 }
 106
 107 #ifdef CONFIG_SMP
 108 #define __set_prev_cpu(thread) ((thread).prev_cpu = smp_processor_id())
 109 #else
 110 #define __set_prev_cpu(thread)
 111 #endif
 112
 113 #define switch_to(prev, next, last)                     \
 114 do {                                                    \
 115         struct task_struct *__prev = (prev);            \
 116         struct task_struct *__next = (next);            \
 117         __set_prev_cpu(__prev->thread);                 \
 118         if (has_fpu())                                  \
 119                 __switch_to_fpu(__prev, __next);        \
 120         if (has_vector())                                       \
 121                 __switch_to_vector(__prev, __next);     \
 122         if (switch_to_should_flush_icache(__next))      \
 123                 local_flush_icache_all();               \
 124         __switch_to_envcfg(__next);                     \
 125         ((last) = __switch_to(__prev, __next));         \
 126 } while (0)
 127
 128 #endif /* _ASM_RISCV_SWITCH_TO_H */