1 /*
2 * linux/arch/i386/kernel/i387.c
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 */
10
11 #include <linux/config.h>
12 #include <linux/sched.h>
13 #include <asm/processor.h>
14 #include <asm/i387.h>
15 #include <asm/math_emu.h>
16 #include <asm/sigcontext.h>
17 #include <asm/user.h>
18 #include <asm/ptrace.h>
19 #include <asm/uaccess.h>
20
21 #ifdef CONFIG_MATH_EMULATION
22 #define HAVE_HWFP (boot_cpu_data.hard_math)
23 #else
24 #define HAVE_HWFP 1
25 #endif
26
27 unsigned long mxcsr_feature_mask = 0xffffffff;
28
29 void mxcsr_feature_mask_init(void)
30 {
31 unsigned long mask = 0;
32 clts();
33 if (cpu_has_fxsr) {
34 memset(¤t->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
35 asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
36 mask = current->thread.i387.fxsave.mxcsr_mask;
37 if (mask == 0) mask = 0x0000ffbf;
38 }
39 mxcsr_feature_mask &= mask;
40 stts();
41 }
42
43 /*
44 * The _current_ task is using the FPU for the first time
45 * so initialize it and set the mxcsr to its default
46 * value at reset if we support XMM instructions and then
47 * remeber the current task has used the FPU.
48 */
49 void init_fpu(struct task_struct *tsk)
50 {
51 if (cpu_has_fxsr) {
52 memset(&tsk->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
53 tsk->thread.i387.fxsave.cwd = 0x37f;
54 if (cpu_has_xmm)
55 tsk->thread.i387.fxsave.mxcsr = 0x1f80;
56 } else {
57 memset(&tsk->thread.i387.fsave, 0, sizeof(struct i387_fsave_struct));
58 tsk->thread.i387.fsave.cwd = 0xffff037fu;
59 tsk->thread.i387.fsave.swd = 0xffff0000u;
60 tsk->thread.i387.fsave.twd = 0xffffffffu;
61 tsk->thread.i387.fsave.fos = 0xffff0000u;
62 }
63 /* only the device not available exception or ptrace can call init_fpu */
64 set_stopped_child_used_math(tsk);
65 }
66
67 /*
68 * FPU lazy state save handling.
69 */
70
71 void kernel_fpu_begin(void)
72 {
73 struct thread_info *thread = current_thread_info();
74
75 preempt_disable();
76 if (thread->status & TS_USEDFPU) {
77 __save_init_fpu(thread->task);
78 return;
79 }
80 clts();
81 }
82
83 void restore_fpu( struct task_struct *tsk )
84 {
85 if ( cpu_has_fxsr ) {
86 asm volatile( "fxrstor %0"
87 : : "m" (tsk->thread.i387.fxsave) );
88 } else {
89 asm volatile( "frstor %0"
90 : : "m" (tsk->thread.i387.fsave) );
91 }
92 }
93
94 /*
95 * FPU tag word conversions.
96 */
97
98 static inline unsigned short twd_i387_to_fxsr( unsigned short twd )
99 {
100 unsigned int tmp; /* to avoid 16 bit prefixes in the code */
101
102 /* Transform each pair of bits into 01 (valid) or 00 (empty) */
103 tmp = ~twd;
104 tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
105 /* and move the valid bits to the lower byte. */
106 tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
107 tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
108 tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
109 return tmp;
110 }
111
112 static inline unsigned long twd_fxsr_to_i387( struct i387_fxsave_struct *fxsave )
113 {
114 struct _fpxreg *st = NULL;
115 unsigned long tos = (fxsave->swd >> 11) & 7;
116 unsigned long twd = (unsigned long) fxsave->twd;
117 unsigned long tag;
118 unsigned long ret = 0xffff0000u;
119 int i;
120
121 #define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16);
122
123 for ( i = 0 ; i < 8 ; i++ ) {
124 if ( twd & 0x1 ) {
125 st = FPREG_ADDR( fxsave, (i - tos) & 7 );
126
127 switch ( st->exponent & 0x7fff ) {
128 case 0x7fff:
129 tag = 2; /* Special */
130 break;
131 case 0x0000:
132 if ( !st->significand[0] &&
133 !st->significand[1] &&
134 !st->significand[2] &&
135 !st->significand[3] ) {
136 tag = 1; /* Zero */
137 } else {
138 tag = 2; /* Special */
139 }
140 break;
141 default:
142 if ( st->significand[3] & 0x8000 ) {
143 tag = 0; /* Valid */
144 } else {
145 tag = 2; /* Special */
146 }
147 break;
148 }
149 } else {
150 tag = 3; /* Empty */
151 }
152 ret |= (tag << (2 * i));
153 twd = twd >> 1;
154 }
155 return ret;
156 }
157
158 /*
159 * FPU state interaction.
160 */
161
162 unsigned short get_fpu_cwd( struct task_struct *tsk )
163 {
164 if ( cpu_has_fxsr ) {
165 return tsk->thread.i387.fxsave.cwd;
166 } else {
167 return (unsigned short)tsk->thread.i387.fsave.cwd;
168 }
169 }
170
171 unsigned short get_fpu_swd( struct task_struct *tsk )
172 {
173 if ( cpu_has_fxsr ) {
174 return tsk->thread.i387.fxsave.swd;
175 } else {
176 return (unsigned short)tsk->thread.i387.fsave.swd;
177 }
178 }
179
180 unsigned short get_fpu_twd( struct task_struct *tsk )
181 {
182 if ( cpu_has_fxsr ) {
183 return tsk->thread.i387.fxsave.twd;
184 } else {
185 return (unsigned short)tsk->thread.i387.fsave.twd;
186 }
187 }
188
189 unsigned short get_fpu_mxcsr( struct task_struct *tsk )
190 {
191 if ( cpu_has_xmm ) {
192 return tsk->thread.i387.fxsave.mxcsr;
193 } else {
194 return 0x1f80;
195 }
196 }
197
198 void set_fpu_cwd( struct task_struct *tsk, unsigned short cwd )
199 {
200 if ( cpu_has_fxsr ) {
201 tsk->thread.i387.fxsave.cwd = cwd;
202 } else {
203 tsk->thread.i387.fsave.cwd = ((long)cwd | 0xffff0000u);
204 }
205 }
206
207 void set_fpu_swd( struct task_struct *tsk, unsigned short swd )
208 {
209 if ( cpu_has_fxsr ) {
210 tsk->thread.i387.fxsave.swd = swd;
211 } else {
212 tsk->thread.i387.fsave.swd = ((long)swd | 0xffff0000u);
213 }
214 }
215
216 void set_fpu_twd( struct task_struct *tsk, unsigned short twd )
217 {
218 if ( cpu_has_fxsr ) {
219 tsk->thread.i387.fxsave.twd = twd_i387_to_fxsr(twd);
220 } else {
221 tsk->thread.i387.fsave.twd = ((long)twd | 0xffff0000u);
222 }
223 }
224
225 /*
226 * FXSR floating point environment conversions.
227 */
228
229 static int convert_fxsr_to_user( struct _fpstate __user *buf,
230 struct i387_fxsave_struct *fxsave )
231 {
232 unsigned long env[7];
233 struct _fpreg __user *to;
234 struct _fpxreg *from;
235 int i;
236
237 env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
238 env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
239 env[2] = twd_fxsr_to_i387(fxsave);
240 env[3] = fxsave->fip;
241 env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
242 env[5] = fxsave->foo;
243 env[6] = fxsave->fos;
244
245 if ( __copy_to_user( buf, env, 7 * sizeof(unsigned long) ) )
246 return 1;
247
248 to = &buf->_st[0];
249 from = (struct _fpxreg *) &fxsave->st_space[0];
250 for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
251 unsigned long __user *t = (unsigned long __user *)to;
252 unsigned long *f = (unsigned long *)from;
253
254 if (__put_user(*f, t) ||
255 __put_user(*(f + 1), t + 1) ||
256 __put_user(from->exponent, &to->exponent))
257 return 1;
258 }
259 return 0;
260 }
261
262 static int convert_fxsr_from_user( struct i387_fxsave_struct *fxsave,
263 struct _fpstate __user *buf )
264 {
265 unsigned long env[7];
266 struct _fpxreg *to;
267 struct _fpreg __user *from;
268 int i;
269
270 if ( __copy_from_user( env, buf, 7 * sizeof(long) ) )
271 return 1;
272
273 fxsave->cwd = (unsigned short)(env[0] & 0xffff);
274 fxsave->swd = (unsigned short)(env[1] & 0xffff);
275 fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
276 fxsave->fip = env[3];
277 fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
278 fxsave->fcs = (env[4] & 0xffff);
279 fxsave->foo = env[5];
280 fxsave->fos = env[6];
281
282 to = (struct _fpxreg *) &fxsave->st_space[0];
283 from = &buf->_st[0];
284 for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
285 unsigned long *t = (unsigned long *)to;
286 unsigned long __user *f = (unsigned long __user *)from;
287
288 if (__get_user(*t, f) ||
289 __get_user(*(t + 1), f + 1) ||
290 __get_user(to->exponent, &from->exponent))
291 return 1;
292 }
293 return 0;
294 }
295
296 /*
297 * Signal frame handlers.
298 */
299
300 static inline int save_i387_fsave( struct _fpstate __user *buf )
301 {
302 struct task_struct *tsk = current;
303
304 unlazy_fpu( tsk );
305 tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
306 if ( __copy_to_user( buf, &tsk->thread.i387.fsave,
307 sizeof(struct i387_fsave_struct) ) )
308 return -1;
309 return 1;
310 }
311
312 static int save_i387_fxsave( struct _fpstate __user *buf )
313 {
314 struct task_struct *tsk = current;
315 int err = 0;
316
317 unlazy_fpu( tsk );
318
319 if ( convert_fxsr_to_user( buf, &tsk->thread.i387.fxsave ) )
320 return -1;
321
322 err |= __put_user( tsk->thread.i387.fxsave.swd, &buf->status );
323 err |= __put_user( X86_FXSR_MAGIC, &buf->magic );
324 if ( err )
325 return -1;
326
327 if ( __copy_to_user( &buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
328 sizeof(struct i387_fxsave_struct) ) )
329 return -1;
330 return 1;
331 }
332
333 int save_i387( struct _fpstate __user *buf )
334 {
335 if ( !used_math() )
336 return 0;
337
338 /* This will cause a "finit" to be triggered by the next
339 * attempted FPU operation by the 'current' process.
340 */
341 clear_used_math();
342
343 if ( HAVE_HWFP ) {
344 if ( cpu_has_fxsr ) {
345 return save_i387_fxsave( buf );
346 } else {
347 return save_i387_fsave( buf );
348 }
349 } else {
350 return save_i387_soft( ¤t->thread.i387.soft, buf );
351 }
352 }
353
354 static inline int restore_i387_fsave( struct _fpstate __user *buf )
355 {
356 struct task_struct *tsk = current;
357 clear_fpu( tsk );
358 return __copy_from_user( &tsk->thread.i387.fsave, buf,
359 sizeof(struct i387_fsave_struct) );
360 }
361
362 static int restore_i387_fxsave( struct _fpstate __user *buf )
363 {
364 int err;
365 struct task_struct *tsk = current;
366 clear_fpu( tsk );
367 err = __copy_from_user( &tsk->thread.i387.fxsave, &buf->_fxsr_env[0],
368 sizeof(struct i387_fxsave_struct) );
369 /* mxcsr reserved bits must be masked to zero for security reasons */
370 tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
371 return err ? 1 : convert_fxsr_from_user( &tsk->thread.i387.fxsave, buf );
372 }
373
374 int restore_i387( struct _fpstate __user *buf )
375 {
376 int err;
377
378 if ( HAVE_HWFP ) {
379 if ( cpu_has_fxsr ) {
380 err = restore_i387_fxsave( buf );
381 } else {
382 err = restore_i387_fsave( buf );
383 }
384 } else {
385 err = restore_i387_soft( ¤t->thread.i387.soft, buf );
386 }
387 set_used_math();
388 return err;
389 }
390
391 /*
392 * ptrace request handlers.
393 */
394
395 static inline int get_fpregs_fsave( struct user_i387_struct __user *buf,
396 struct task_struct *tsk )
397 {
398 return __copy_to_user( buf, &tsk->thread.i387.fsave,
399 sizeof(struct user_i387_struct) );
400 }
401
402 static inline int get_fpregs_fxsave( struct user_i387_struct __user *buf,
403 struct task_struct *tsk )
404 {
405 return convert_fxsr_to_user( (struct _fpstate __user *)buf,
406 &tsk->thread.i387.fxsave );
407 }
408
409 int get_fpregs( struct user_i387_struct __user *buf, struct task_struct *tsk )
410 {
411 if ( HAVE_HWFP ) {
412 if ( cpu_has_fxsr ) {
413 return get_fpregs_fxsave( buf, tsk );
414 } else {
415 return get_fpregs_fsave( buf, tsk );
416 }
417 } else {
418 return save_i387_soft( &tsk->thread.i387.soft,
419 (struct _fpstate __user *)buf );
420 }
421 }
422
423 static inline int set_fpregs_fsave( struct task_struct *tsk,
424 struct user_i387_struct __user *buf )
425 {
426 return __copy_from_user( &tsk->thread.i387.fsave, buf,
427 sizeof(struct user_i387_struct) );
428 }
429
430 static inline int set_fpregs_fxsave( struct task_struct *tsk,
431 struct user_i387_struct __user *buf )
432 {
433 return convert_fxsr_from_user( &tsk->thread.i387.fxsave,
434 (struct _fpstate __user *)buf );
435 }
436
437 int set_fpregs( struct task_struct *tsk, struct user_i387_struct __user *buf )
438 {
439 if ( HAVE_HWFP ) {
440 if ( cpu_has_fxsr ) {
441 return set_fpregs_fxsave( tsk, buf );
442 } else {
443 return set_fpregs_fsave( tsk, buf );
444 }
445 } else {
446 return restore_i387_soft( &tsk->thread.i387.soft,
447 (struct _fpstate __user *)buf );
448 }
449 }
450
451 int get_fpxregs( struct user_fxsr_struct __user *buf, struct task_struct *tsk )
452 {
453 if ( cpu_has_fxsr ) {
454 if (__copy_to_user( buf, &tsk->thread.i387.fxsave,
455 sizeof(struct user_fxsr_struct) ))
456 return -EFAULT;
457 return 0;
458 } else {
459 return -EIO;
460 }
461 }
462
463 int set_fpxregs( struct task_struct *tsk, struct user_fxsr_struct __user *buf )
464 {
465 int ret = 0;
466
467 if ( cpu_has_fxsr ) {
468 if (__copy_from_user( &tsk->thread.i387.fxsave, buf,
469 sizeof(struct user_fxsr_struct) ))
470 ret = -EFAULT;
471 /* mxcsr reserved bits must be masked to zero for security reasons */
472 tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
473 } else {
474 ret = -EIO;
475 }
476 return ret;
477 }
478
479 /*
480 * FPU state for core dumps.
481 */
482
483 static inline void copy_fpu_fsave( struct task_struct *tsk,
484 struct user_i387_struct *fpu )
485 {
486 memcpy( fpu, &tsk->thread.i387.fsave,
487 sizeof(struct user_i387_struct) );
488 }
489
490 static inline void copy_fpu_fxsave( struct task_struct *tsk,
491 struct user_i387_struct *fpu )
492 {
493 unsigned short *to;
494 unsigned short *from;
495 int i;
496
497 memcpy( fpu, &tsk->thread.i387.fxsave, 7 * sizeof(long) );
498
499 to = (unsigned short *)&fpu->st_space[0];
500 from = (unsigned short *)&tsk->thread.i387.fxsave.st_space[0];
501 for ( i = 0 ; i < 8 ; i++, to += 5, from += 8 ) {
502 memcpy( to, from, 5 * sizeof(unsigned short) );
503 }
504 }
505
506 int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
507 {
508 int fpvalid;
509 struct task_struct *tsk = current;
510
511 fpvalid = !!used_math();
512 if ( fpvalid ) {
513 unlazy_fpu( tsk );
514 if ( cpu_has_fxsr ) {
515 copy_fpu_fxsave( tsk, fpu );
516 } else {
517 copy_fpu_fsave( tsk, fpu );
518 }
519 }
520
521 return fpvalid;
522 }
523
524 int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
525 {
526 int fpvalid = !!tsk_used_math(tsk);
527
528 if (fpvalid) {
529 if (tsk == current)
530 unlazy_fpu(tsk);
531 if (cpu_has_fxsr)
532 copy_fpu_fxsave(tsk, fpu);
533 else
534 copy_fpu_fsave(tsk, fpu);
535 }
536 return fpvalid;
537 }
538
539 int dump_task_extended_fpu(struct task_struct *tsk, struct user_fxsr_struct *fpu)
540 {
541 int fpvalid = tsk_used_math(tsk) && cpu_has_fxsr;
542
543 if (fpvalid) {
544 if (tsk == current)
545 unlazy_fpu(tsk);
546 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(*fpu));
547 }
548 return fpvalid;
549 }
550
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