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