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-rw-r--r--arch/x86/ia32/fpu32.c183
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/x86/ia32/fpu32.c b/arch/x86/ia32/fpu32.c
new file mode 100644
index 000000000000..2c8209a3605a
--- /dev/null
+++ b/arch/x86/ia32/fpu32.c
@@ -0,0 +1,183 @@
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
13static 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
27static 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
74static 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
107static 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
150int 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
164int 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}
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