[PATCH] mm: update comments to pte lock
[linux-2.6.git] / arch / x86_64 / ia32 / fpu32.c
1 /* 
2  * Copyright 2002 Andi Kleen, SuSE Labs.
3  * FXSAVE<->i387 conversion support. Based on code by Gareth Hughes.
4  * This is used for ptrace, signals and coredumps in 32bit emulation.
5  * $Id: fpu32.c,v 1.1 2002/03/21 14:16:32 ak Exp $
6  */ 
7
8 #include <linux/sched.h>
9 #include <asm/sigcontext32.h>
10 #include <asm/processor.h>
11 #include <asm/uaccess.h>
12 #include <asm/i387.h>
13
14 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
15 {
16         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
17  
18         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
19         tmp = ~twd;
20         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
21         /* and move the valid bits to the lower byte. */
22         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
23         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
24         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
25         return tmp;
26 }
27
28 static inline unsigned long twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
29 {
30         struct _fpxreg *st = NULL;
31         unsigned long tos = (fxsave->swd >> 11) & 7;
32         unsigned long twd = (unsigned long) fxsave->twd;
33         unsigned long tag;
34         unsigned long ret = 0xffff0000;
35         int i;
36
37 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16);
38
39         for (i = 0 ; i < 8 ; i++) {
40                 if (twd & 0x1) {
41                         st = FPREG_ADDR( fxsave, (i - tos) & 7 );
42
43                         switch (st->exponent & 0x7fff) {
44                         case 0x7fff:
45                                 tag = 2;                /* Special */
46                                 break;
47                         case 0x0000:
48                                 if ( !st->significand[0] &&
49                                      !st->significand[1] &&
50                                      !st->significand[2] &&
51                                      !st->significand[3] ) {
52                                         tag = 1;        /* Zero */
53                                 } else {
54                                         tag = 2;        /* Special */
55                                 }
56                                 break;
57                         default:
58                                 if (st->significand[3] & 0x8000) {
59                                         tag = 0;        /* Valid */
60                                 } else {
61                                         tag = 2;        /* Special */
62                                 }
63                                 break;
64                         }
65                 } else {
66                         tag = 3;                        /* Empty */
67                 }
68                 ret |= (tag << (2 * i));
69                 twd = twd >> 1;
70         }
71         return ret;
72 }
73
74
75 static inline int convert_fxsr_from_user(struct i387_fxsave_struct *fxsave,
76                                          struct _fpstate_ia32 __user *buf)
77 {
78         struct _fpxreg *to;
79         struct _fpreg __user *from;
80         int i;
81         u32 v;
82         int err = 0;
83
84 #define G(num,val) err |= __get_user(val, num + (u32 __user *)buf)
85         G(0, fxsave->cwd);
86         G(1, fxsave->swd);
87         G(2, fxsave->twd);
88         fxsave->twd = twd_i387_to_fxsr(fxsave->twd);
89         G(3, fxsave->rip);
90         G(4, v);
91         fxsave->fop = v>>16;    /* cs ignored */
92         G(5, fxsave->rdp);
93         /* 6: ds ignored */
94 #undef G
95         if (err) 
96                 return -1; 
97
98         to = (struct _fpxreg *)&fxsave->st_space[0];
99         from = &buf->_st[0];
100         for (i = 0 ; i < 8 ; i++, to++, from++) {
101                 if (__copy_from_user(to, from, sizeof(*from)))
102                         return -1;
103         }
104         return 0;
105 }
106
107
108 static inline int convert_fxsr_to_user(struct _fpstate_ia32 __user *buf,
109                                        struct i387_fxsave_struct *fxsave,
110                                        struct pt_regs *regs,
111                                        struct task_struct *tsk)
112 {
113         struct _fpreg __user *to;
114         struct _fpxreg *from;
115         int i;
116         u16 cs,ds; 
117         int err = 0; 
118
119         if (tsk == current) {
120                 /* should be actually ds/cs at fpu exception time,
121                    but that information is not available in 64bit mode. */
122                 asm("movw %%ds,%0 " : "=r" (ds)); 
123                 asm("movw %%cs,%0 " : "=r" (cs));               
124         } else { /* ptrace. task has stopped. */
125                 ds = tsk->thread.ds;
126                 cs = regs->cs;
127         } 
128
129 #define P(num,val) err |= __put_user(val, num + (u32 __user *)buf)
130         P(0, (u32)fxsave->cwd | 0xffff0000);
131         P(1, (u32)fxsave->swd | 0xffff0000);
132         P(2, twd_fxsr_to_i387(fxsave));
133         P(3, (u32)fxsave->rip);
134         P(4,  cs | ((u32)fxsave->fop) << 16); 
135         P(5, fxsave->rdp);
136         P(6, 0xffff0000 | ds);
137 #undef P
138
139         if (err) 
140                 return -1; 
141
142         to = &buf->_st[0];
143         from = (struct _fpxreg *) &fxsave->st_space[0];
144         for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
145                 if (__copy_to_user(to, from, sizeof(*to)))
146                         return -1;
147         }
148         return 0;
149 }
150
151 int restore_i387_ia32(struct task_struct *tsk, struct _fpstate_ia32 __user *buf, int fsave) 
152
153         clear_fpu(tsk);
154         if (!fsave) { 
155                 if (__copy_from_user(&tsk->thread.i387.fxsave, 
156                                      &buf->_fxsr_env[0],
157                                      sizeof(struct i387_fxsave_struct)))
158                         return -1;
159                 tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
160                 set_stopped_child_used_math(tsk);
161         } 
162         return convert_fxsr_from_user(&tsk->thread.i387.fxsave, buf);
163 }  
164
165 int save_i387_ia32(struct task_struct *tsk, 
166                    struct _fpstate_ia32 __user *buf, 
167                    struct pt_regs *regs,
168                    int fsave)
169 {
170         int err = 0;
171
172         init_fpu(tsk);
173         if (convert_fxsr_to_user(buf, &tsk->thread.i387.fxsave, regs, tsk))
174                 return -1;
175         if (fsave)
176                 return 0;
177         err |= __put_user(tsk->thread.i387.fxsave.swd, &buf->status);
178         if (fsave) 
179                 return err ? -1 : 1;    
180         err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
181         err |= __copy_to_user(&buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
182                               sizeof(struct i387_fxsave_struct));
183         return err ? -1 : 1;
184 }