arch/x86/include/asm/fpu/api.h

   1 /*
   2  * Copyright (C) 1994 Linus Torvalds
   3  *
   4  * Pentium III FXSR, SSE support
   5  * General FPU state handling cleanups
   6  *      Gareth Hughes <gareth@valinux.com>, May 2000
   7  * x86-64 work by Andi Kleen 2002
   8  */
   9
  10 #ifndef _ASM_X86_FPU_API_H
  11 #define _ASM_X86_FPU_API_H
  12
  13 /*
  14  * Careful: __kernel_fpu_begin/end() must be called with preempt disabled
  15  * and they don't touch the preempt state on their own.
  16  * If you enable preemption after __kernel_fpu_begin(), preempt notifier
  17  * should call the __kernel_fpu_end() to prevent the kernel/user FPU
  18  * state from getting corrupted. KVM for example uses this model.
  19  *
  20  * All other cases use kernel_fpu_begin/end() which disable preemption
  21  * during kernel FPU usage.
  22  */
  23 extern void __kernel_fpu_begin(void);
  24 extern void __kernel_fpu_end(void);
  25 extern void kernel_fpu_begin(void);
  26 extern void kernel_fpu_end(void);
  27 extern bool irq_fpu_usable(void);
  28
  29 /*
  30  * Some instructions like VIA's padlock instructions generate a spurious
  31  * DNA fault but don't modify SSE registers. And these instructions
  32  * get used from interrupt context as well. To prevent these kernel instructions
  33  * in interrupt context interacting wrongly with other user/kernel fpu usage, we
  34  * should use them only in the context of irq_ts_save/restore()
  35  */
  36 extern int  irq_ts_save(void);
  37 extern void irq_ts_restore(int TS_state);
  38
  39 /*
  40  * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
  41  *
  42  * If 'feature_name' is set then put a human-readable description of
  43  * the feature there as well - this can be used to print error (or success)
  44  * messages.
  45  */
  46 extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
  47
  48 #endif /* _ASM_X86_FPU_API_H */