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-rw-r--r--include/asm-x86/i387_64.h209
1 files changed, 209 insertions, 0 deletions
diff --git a/include/asm-x86/i387_64.h b/include/asm-x86/i387_64.h
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1/*
2 * include/asm-x86_64/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 * x86-64 work by Andi Kleen 2002
10 */
11
12#ifndef __ASM_X86_64_I387_H
13#define __ASM_X86_64_I387_H
14
15#include <linux/sched.h>
16#include <asm/processor.h>
17#include <asm/sigcontext.h>
18#include <asm/user.h>
19#include <asm/thread_info.h>
20#include <asm/uaccess.h>
21
22extern void fpu_init(void);
23extern unsigned int mxcsr_feature_mask;
24extern void mxcsr_feature_mask_init(void);
25extern void init_fpu(struct task_struct *child);
26extern int save_i387(struct _fpstate __user *buf);
27extern asmlinkage void math_state_restore(void);
28
29/*
30 * FPU lazy state save handling...
31 */
32
33#define unlazy_fpu(tsk) do { \
34 if (task_thread_info(tsk)->status & TS_USEDFPU) \
35 save_init_fpu(tsk); \
36 else \
37 tsk->fpu_counter = 0; \
38} while (0)
39
40/* Ignore delayed exceptions from user space */
41static inline void tolerant_fwait(void)
42{
43 asm volatile("1: fwait\n"
44 "2:\n"
45 " .section __ex_table,\"a\"\n"
46 " .align 8\n"
47 " .quad 1b,2b\n"
48 " .previous\n");
49}
50
51#define clear_fpu(tsk) do { \
52 if (task_thread_info(tsk)->status & TS_USEDFPU) { \
53 tolerant_fwait(); \
54 task_thread_info(tsk)->status &= ~TS_USEDFPU; \
55 stts(); \
56 } \
57} while (0)
58
59/*
60 * ptrace request handers...
61 */
62extern int get_fpregs(struct user_i387_struct __user *buf,
63 struct task_struct *tsk);
64extern int set_fpregs(struct task_struct *tsk,
65 struct user_i387_struct __user *buf);
66
67/*
68 * i387 state interaction
69 */
70#define get_fpu_mxcsr(t) ((t)->thread.i387.fxsave.mxcsr)
71#define get_fpu_cwd(t) ((t)->thread.i387.fxsave.cwd)
72#define get_fpu_fxsr_twd(t) ((t)->thread.i387.fxsave.twd)
73#define get_fpu_swd(t) ((t)->thread.i387.fxsave.swd)
74#define set_fpu_cwd(t,val) ((t)->thread.i387.fxsave.cwd = (val))
75#define set_fpu_swd(t,val) ((t)->thread.i387.fxsave.swd = (val))
76#define set_fpu_fxsr_twd(t,val) ((t)->thread.i387.fxsave.twd = (val))
77
78#define X87_FSW_ES (1 << 7) /* Exception Summary */
79
80/* AMD CPUs don't save/restore FDP/FIP/FOP unless an exception
81 is pending. Clear the x87 state here by setting it to fixed
82 values. The kernel data segment can be sometimes 0 and sometimes
83 new user value. Both should be ok.
84 Use the PDA as safe address because it should be already in L1. */
85static inline void clear_fpu_state(struct i387_fxsave_struct *fx)
86{
87 if (unlikely(fx->swd & X87_FSW_ES))
88 asm volatile("fnclex");
89 alternative_input(ASM_NOP8 ASM_NOP2,
90 " emms\n" /* clear stack tags */
91 " fildl %%gs:0", /* load to clear state */
92 X86_FEATURE_FXSAVE_LEAK);
93}
94
95static inline int restore_fpu_checking(struct i387_fxsave_struct *fx)
96{
97 int err;
98
99 asm volatile("1: rex64/fxrstor (%[fx])\n\t"
100 "2:\n"
101 ".section .fixup,\"ax\"\n"
102 "3: movl $-1,%[err]\n"
103 " jmp 2b\n"
104 ".previous\n"
105 ".section __ex_table,\"a\"\n"
106 " .align 8\n"
107 " .quad 1b,3b\n"
108 ".previous"
109 : [err] "=r" (err)
110#if 0 /* See comment in __fxsave_clear() below. */
111 : [fx] "r" (fx), "m" (*fx), "0" (0));
112#else
113 : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
114#endif
115 if (unlikely(err))
116 init_fpu(current);
117 return err;
118}
119
120static inline int save_i387_checking(struct i387_fxsave_struct __user *fx)
121{
122 int err;
123
124 asm volatile("1: rex64/fxsave (%[fx])\n\t"
125 "2:\n"
126 ".section .fixup,\"ax\"\n"
127 "3: movl $-1,%[err]\n"
128 " jmp 2b\n"
129 ".previous\n"
130 ".section __ex_table,\"a\"\n"
131 " .align 8\n"
132 " .quad 1b,3b\n"
133 ".previous"
134 : [err] "=r" (err), "=m" (*fx)
135#if 0 /* See comment in __fxsave_clear() below. */
136 : [fx] "r" (fx), "0" (0));
137#else
138 : [fx] "cdaSDb" (fx), "0" (0));
139#endif
140 if (unlikely(err) && __clear_user(fx, sizeof(struct i387_fxsave_struct)))
141 err = -EFAULT;
142 /* No need to clear here because the caller clears USED_MATH */
143 return err;
144}
145
146static inline void __fxsave_clear(struct task_struct *tsk)
147{
148 /* Using "rex64; fxsave %0" is broken because, if the memory operand
149 uses any extended registers for addressing, a second REX prefix
150 will be generated (to the assembler, rex64 followed by semicolon
151 is a separate instruction), and hence the 64-bitness is lost. */
152#if 0
153 /* Using "fxsaveq %0" would be the ideal choice, but is only supported
154 starting with gas 2.16. */
155 __asm__ __volatile__("fxsaveq %0"
156 : "=m" (tsk->thread.i387.fxsave));
157#elif 0
158 /* Using, as a workaround, the properly prefixed form below isn't
159 accepted by any binutils version so far released, complaining that
160 the same type of prefix is used twice if an extended register is
161 needed for addressing (fix submitted to mainline 2005-11-21). */
162 __asm__ __volatile__("rex64/fxsave %0"
163 : "=m" (tsk->thread.i387.fxsave));
164#else
165 /* This, however, we can work around by forcing the compiler to select
166 an addressing mode that doesn't require extended registers. */
167 __asm__ __volatile__("rex64/fxsave %P2(%1)"
168 : "=m" (tsk->thread.i387.fxsave)
169 : "cdaSDb" (tsk),
170 "i" (offsetof(__typeof__(*tsk),
171 thread.i387.fxsave)));
172#endif
173 clear_fpu_state(&tsk->thread.i387.fxsave);
174}
175
176static inline void kernel_fpu_begin(void)
177{
178 struct thread_info *me = current_thread_info();
179 preempt_disable();
180 if (me->status & TS_USEDFPU) {
181 __fxsave_clear(me->task);
182 me->status &= ~TS_USEDFPU;
183 return;
184 }
185 clts();
186}
187
188static inline void kernel_fpu_end(void)
189{
190 stts();
191 preempt_enable();
192}
193
194static inline void save_init_fpu(struct task_struct *tsk)
195{
196 __fxsave_clear(tsk);
197 task_thread_info(tsk)->status &= ~TS_USEDFPU;
198 stts();
199}
200
201/*
202 * This restores directly out of user space. Exceptions are handled.
203 */
204static inline int restore_i387(struct _fpstate __user *buf)
205{
206 return restore_fpu_checking((__force struct i387_fxsave_struct *)buf);
207}
208
209#endif /* __ASM_X86_64_I387_H */
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