1/*
2 * include/asm-i386/i387.h
3 *
4 * Copyright (C) 1994 Linus Torvalds
5 *
6 * Pentium III FXSR, SSE support
7 * General FPU state handling cleanups
8 *	Gareth Hughes <gareth@valinux.com>, May 2000
9 */
10
11#ifndef __ASM_I386_I387_H
12#define __ASM_I386_I387_H
13
14#include <linux/sched.h>
15#include <linux/init.h>
16#include <linux/kernel_stat.h>
17#include <asm/processor.h>
18#include <asm/sigcontext.h>
19#include <asm/user.h>
20
21extern void mxcsr_feature_mask_init(void);
22extern void init_fpu(struct task_struct *);
23
24/*
25 * FPU lazy state save handling...
26 */
27
28/*
29 * The "nop" is needed to make the instructions the same
30 * length.
31 */
32#define restore_fpu(tsk)			\
33	alternative_input(			\
34		"nop ; frstor %1",		\
35		"fxrstor %1",			\
36		X86_FEATURE_FXSR,		\
37		"m" ((tsk)->thread.i387.fxsave))
38
39extern void kernel_fpu_begin(void);
40#define kernel_fpu_end() do { stts(); preempt_enable(); } while(0)
41
42/* We need a safe address that is cheap to find and that is already
43   in L1 during context switch. The best choices are unfortunately
44   different for UP and SMP */
45#ifdef CONFIG_SMP
46#define safe_address (__per_cpu_offset[0])
47#else
48#define safe_address (kstat_cpu(0).cpustat.user)
49#endif
50
51/*
52 * These must be called with preempt disabled
53 */
54static inline void __save_init_fpu( struct task_struct *tsk )
55{
56	/* Use more nops than strictly needed in case the compiler
57	   varies code */
58	alternative_input(
59		"fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
60		"fxsave %[fx]\n"
61		"bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
62		X86_FEATURE_FXSR,
63		[fx] "m" (tsk->thread.i387.fxsave),
64		[fsw] "m" (tsk->thread.i387.fxsave.swd) : "memory");
65	/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
66	   is pending.  Clear the x87 state here by setting it to fixed
67   	   values. safe_address is a random variable that should be in L1 */
68	alternative_input(
69		GENERIC_NOP8 GENERIC_NOP2,
70		"emms\n\t"	  	/* clear stack tags */
71		"fildl %[addr]", 	/* set F?P to defined value */
72		X86_FEATURE_FXSAVE_LEAK,
73		[addr] "m" (safe_address));
74	task_thread_info(tsk)->status &= ~TS_USEDFPU;
75}
76
77#define __unlazy_fpu( tsk ) do {				\
78	if (task_thread_info(tsk)->status & TS_USEDFPU) {	\
79		__save_init_fpu(tsk);				\
80		stts();						\
81	} else							\
82		tsk->fpu_counter = 0;				\
83} while (0)
84
85#define __clear_fpu( tsk )					\
86do {								\
87	if (task_thread_info(tsk)->status & TS_USEDFPU) {	\
88		asm volatile("fnclex ; fwait");			\
89		task_thread_info(tsk)->status &= ~TS_USEDFPU;	\
90		stts();						\
91	}							\
92} while (0)
93
94
95/*
96 * These disable preemption on their own and are safe
97 */
98static inline void save_init_fpu( struct task_struct *tsk )
99{
100	preempt_disable();
101	__save_init_fpu(tsk);
102	stts();
103	preempt_enable();
104}
105
106#define unlazy_fpu( tsk ) do {	\
107	preempt_disable();	\
108	__unlazy_fpu(tsk);	\
109	preempt_enable();	\
110} while (0)
111
112#define clear_fpu( tsk ) do {	\
113	preempt_disable();	\
114	__clear_fpu( tsk );	\
115	preempt_enable();	\
116} while (0)
117
118/*
119 * FPU state interaction...
120 */
121extern unsigned short get_fpu_cwd( struct task_struct *tsk );
122extern unsigned short get_fpu_swd( struct task_struct *tsk );
123extern unsigned short get_fpu_mxcsr( struct task_struct *tsk );
124extern asmlinkage void math_state_restore(void);
125
126/*
127 * Signal frame handlers...
128 */
129extern int save_i387( struct _fpstate __user *buf );
130extern int restore_i387( struct _fpstate __user *buf );
131
132/*
133 * ptrace request handers...
134 */
135extern int get_fpregs( struct user_i387_struct __user *buf,
136		       struct task_struct *tsk );
137extern int set_fpregs( struct task_struct *tsk,
138		       struct user_i387_struct __user *buf );
139
140extern int get_fpxregs( struct user_fxsr_struct __user *buf,
141			struct task_struct *tsk );
142extern int set_fpxregs( struct task_struct *tsk,
143			struct user_fxsr_struct __user *buf );
144
145/*
146 * FPU state for core dumps...
147 */
148extern int dump_fpu( struct pt_regs *regs,
149		     struct user_i387_struct *fpu );
150
151#endif /* __ASM_I386_I387_H */
152