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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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);
27
28/*
29 * FPU lazy state save handling...
30 */
31
32#define unlazy_fpu(tsk) do { \
Al Viroe4f17c42006-01-12 01:05:38 -080033 if (task_thread_info(tsk)->status & TS_USEDFPU) \
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 save_init_fpu(tsk); \
35} while (0)
36
37/* Ignore delayed exceptions from user space */
38static inline void tolerant_fwait(void)
39{
40 asm volatile("1: fwait\n"
41 "2:\n"
42 " .section __ex_table,\"a\"\n"
43 " .align 8\n"
44 " .quad 1b,2b\n"
45 " .previous\n");
46}
47
48#define clear_fpu(tsk) do { \
Al Viroe4f17c42006-01-12 01:05:38 -080049 if (task_thread_info(tsk)->status & TS_USEDFPU) { \
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 tolerant_fwait(); \
Al Viroe4f17c42006-01-12 01:05:38 -080051 task_thread_info(tsk)->status &= ~TS_USEDFPU; \
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 stts(); \
53 } \
54} while (0)
55
56/*
57 * ptrace request handers...
58 */
59extern int get_fpregs(struct user_i387_struct __user *buf,
60 struct task_struct *tsk);
61extern int set_fpregs(struct task_struct *tsk,
62 struct user_i387_struct __user *buf);
63
64/*
65 * i387 state interaction
66 */
67#define get_fpu_mxcsr(t) ((t)->thread.i387.fxsave.mxcsr)
68#define get_fpu_cwd(t) ((t)->thread.i387.fxsave.cwd)
69#define get_fpu_fxsr_twd(t) ((t)->thread.i387.fxsave.twd)
70#define get_fpu_swd(t) ((t)->thread.i387.fxsave.swd)
71#define set_fpu_cwd(t,val) ((t)->thread.i387.fxsave.cwd = (val))
72#define set_fpu_swd(t,val) ((t)->thread.i387.fxsave.swd = (val))
73#define set_fpu_fxsr_twd(t,val) ((t)->thread.i387.fxsave.twd = (val))
74
75static inline int restore_fpu_checking(struct i387_fxsave_struct *fx)
76{
77 int err;
Jan Beulich7180d4f2006-01-11 22:43:36 +010078
79 asm volatile("1: rex64/fxrstor (%[fx])\n\t"
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 "2:\n"
81 ".section .fixup,\"ax\"\n"
82 "3: movl $-1,%[err]\n"
83 " jmp 2b\n"
84 ".previous\n"
85 ".section __ex_table,\"a\"\n"
86 " .align 8\n"
87 " .quad 1b,3b\n"
88 ".previous"
89 : [err] "=r" (err)
Jan Beulich7180d4f2006-01-11 22:43:36 +010090#if 0 /* See comment in __fxsave_clear() below. */
91 : [fx] "r" (fx), "m" (*fx), "0" (0));
92#else
93 : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
94#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 if (unlikely(err))
96 init_fpu(current);
97 return err;
98}
99
100static inline int save_i387_checking(struct i387_fxsave_struct __user *fx)
101{
102 int err;
Jan Beulich7180d4f2006-01-11 22:43:36 +0100103
104 asm volatile("1: rex64/fxsave (%[fx])\n\t"
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 "2:\n"
106 ".section .fixup,\"ax\"\n"
107 "3: movl $-1,%[err]\n"
108 " jmp 2b\n"
109 ".previous\n"
110 ".section __ex_table,\"a\"\n"
111 " .align 8\n"
112 " .quad 1b,3b\n"
113 ".previous"
Jan Beulich7180d4f2006-01-11 22:43:36 +0100114 : [err] "=r" (err), "=m" (*fx)
115#if 0 /* See comment in __fxsave_clear() below. */
116 : [fx] "r" (fx), "0" (0));
117#else
118 : [fx] "cdaSDb" (fx), "0" (0));
119#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 if (unlikely(err))
121 __clear_user(fx, sizeof(struct i387_fxsave_struct));
122 return err;
123}
124
Jan Beulich7180d4f2006-01-11 22:43:36 +0100125static inline void __fxsave_clear(struct task_struct *tsk)
126{
127 /* Using "rex64; fxsave %0" is broken because, if the memory operand
128 uses any extended registers for addressing, a second REX prefix
129 will be generated (to the assembler, rex64 followed by semicolon
130 is a separate instruction), and hence the 64-bitness is lost. */
131#if 0
132 /* Using "fxsaveq %0" would be the ideal choice, but is only supported
133 starting with gas 2.16. */
134 __asm__ __volatile__("fxsaveq %0"
135 : "=m" (tsk->thread.i387.fxsave));
136#elif 0
137 /* Using, as a workaround, the properly prefixed form below isn't
138 accepted by any binutils version so far released, complaining that
139 the same type of prefix is used twice if an extended register is
140 needed for addressing (fix submitted to mainline 2005-11-21). */
141 __asm__ __volatile__("rex64/fxsave %0"
142 : "=m" (tsk->thread.i387.fxsave));
143#else
144 /* This, however, we can work around by forcing the compiler to select
145 an addressing mode that doesn't require extended registers. */
146 __asm__ __volatile__("rex64/fxsave %P2(%1)"
147 : "=m" (tsk->thread.i387.fxsave)
148 : "cdaSDb" (tsk),
149 "i" (offsetof(__typeof__(*tsk),
150 thread.i387.fxsave)));
151#endif
152 __asm__ __volatile__("fnclex");
153}
154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155static inline void kernel_fpu_begin(void)
156{
157 struct thread_info *me = current_thread_info();
158 preempt_disable();
Jan Beulich7180d4f2006-01-11 22:43:36 +0100159 if (me->status & TS_USEDFPU) {
160 __fxsave_clear(me->task);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 me->status &= ~TS_USEDFPU;
162 return;
163 }
164 clts();
165}
166
167static inline void kernel_fpu_end(void)
168{
169 stts();
170 preempt_enable();
171}
172
Al Viroe4f17c42006-01-12 01:05:38 -0800173static inline void save_init_fpu(struct task_struct *tsk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174{
Jan Beulich7180d4f2006-01-11 22:43:36 +0100175 __fxsave_clear(tsk);
Al Viroe4f17c42006-01-12 01:05:38 -0800176 task_thread_info(tsk)->status &= ~TS_USEDFPU;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 stts();
178}
179
180/*
181 * This restores directly out of user space. Exceptions are handled.
182 */
183static inline int restore_i387(struct _fpstate __user *buf)
184{
185 return restore_fpu_checking((__force struct i387_fxsave_struct *)buf);
186}
187
188#endif /* __ASM_X86_64_I387_H */