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 */ 49