aboutsummaryrefslogtreecommitdiff
path: root/arch/i386/kernel/i387.c
blob: c4351972d9afc7b5c4b2e39b5222f8f52b930eba (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
/*
 *  linux/arch/i386/kernel/i387.c
 *
 *  Copyright (C) 1994 Linus Torvalds
 *
 *  Pentium III FXSR, SSE support
 *  General FPU state handling cleanups
 *	Gareth Hughes <gareth@valinux.com>, May 2000
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/math_emu.h>
#include <asm/sigcontext.h>
#include <asm/user.h>
#include <asm/ptrace.h>
#include <asm/uaccess.h>

#ifdef CONFIG_MATH_EMULATION
#define HAVE_HWFP (boot_cpu_data.hard_math)
#else
#define HAVE_HWFP 1
#endif

static unsigned long mxcsr_feature_mask __read_mostly = 0xffffffff;

void mxcsr_feature_mask_init(void)
{
	unsigned long mask = 0;
	clts();
	if (cpu_has_fxsr) {
		memset(&current->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
		asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave)); 
		mask = current->thread.i387.fxsave.mxcsr_mask;
		if (mask == 0) mask = 0x0000ffbf;
	} 
	mxcsr_feature_mask &= mask;
	stts();
}

/*
 * The _current_ task is using the FPU for the first time
 * so initialize it and set the mxcsr to its default
 * value at reset if we support XMM instructions and then
 * remeber the current task has used the FPU.
 */
void init_fpu(struct task_struct *tsk)
{
	if (cpu_has_fxsr) {
		memset(&tsk->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
		tsk->thread.i387.fxsave.cwd = 0x37f;
		if (cpu_has_xmm)
			tsk->thread.i387.fxsave.mxcsr = 0x1f80;
	} else {
		memset(&tsk->thread.i387.fsave, 0, sizeof(struct i387_fsave_struct));
		tsk->thread.i387.fsave.cwd = 0xffff037fu;
		tsk->thread.i387.fsave.swd = 0xffff0000u;
		tsk->thread.i387.fsave.twd = 0xffffffffu;
		tsk->thread.i387.fsave.fos = 0xffff0000u;
	}
	/* only the device not available exception or ptrace can call init_fpu */
	set_stopped_child_used_math(tsk);
}

/*
 * FPU lazy state save handling.
 */

void kernel_fpu_begin(void)
{
	struct thread_info *thread = current_thread_info();

	preempt_disable();
	if (thread->status & TS_USEDFPU) {
		__save_init_fpu(thread->task);
		return;
	}
	clts();
}
EXPORT_SYMBOL_GPL(kernel_fpu_begin);

/*
 * FPU tag word conversions.
 */

static inline unsigned short twd_i387_to_fxsr( unsigned short twd )
{
	unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 
	/* Transform each pair of bits into 01 (valid) or 00 (empty) */
        tmp = ~twd;
        tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
        /* and move the valid bits to the lower byte. */
        tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
        tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
        tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
        return tmp;
}

static inline unsigned long twd_fxsr_to_i387( struct i387_fxsave_struct *fxsave )
{
	struct _fpxreg *st = NULL;
	unsigned long tos = (fxsave->swd >> 11) & 7;
	unsigned long twd = (unsigned long) fxsave->twd;
	unsigned long tag;
	unsigned long ret = 0xffff0000u;
	int i;

#define FPREG_ADDR(f, n)	((void *)&(f)->st_space + (n) * 16);

	for ( i = 0 ; i < 8 ; i++ ) {
		if ( twd & 0x1 ) {
			st = FPREG_ADDR( fxsave, (i - tos) & 7 );

			switch ( st->exponent & 0x7fff ) {
			case 0x7fff:
				tag = 2;		/* Special */
				break;
			case 0x0000:
				if ( !st->significand[0] &&
				     !st->significand[1] &&
				     !st->significand[2] &&
				     !st->significand[3] ) {
					tag = 1;	/* Zero */
				} else {
					tag = 2;	/* Special */
				}
				break;
			default:
				if ( st->significand[3] & 0x8000 ) {
					tag = 0;	/* Valid */
				} else {
					tag = 2;	/* Special */
				}
				break;
			}
		} else {
			tag = 3;			/* Empty */
		}
		ret |= (tag << (2 * i));
		twd = twd >> 1;
	}
	return ret;
}

/*
 * FPU state interaction.
 */

unsigned short get_fpu_cwd( struct task_struct *tsk )
{
	if ( cpu_has_fxsr ) {
		return tsk->thread.i387.fxsave.cwd;
	} else {
		return (unsigned short)tsk->thread.i387.fsave.cwd;
	}
}

unsigned short get_fpu_swd( struct task_struct *tsk )
{
	if ( cpu_has_fxsr ) {
		return tsk->thread.i387.fxsave.swd;
	} else {
		return (unsigned short)tsk->thread.i387.fsave.swd;
	}
}

#if 0
unsigned short get_fpu_twd( struct task_struct *tsk )
{
	if ( cpu_has_fxsr ) {
		return tsk->thread.i387.fxsave.twd;
	} else {
		return (unsigned short)tsk->thread.i387.fsave.twd;
	}
}
#endif  /*  0  */

unsigned short get_fpu_mxcsr( struct task_struct *tsk )
{
	if ( cpu_has_xmm ) {
		return tsk->thread.i387.fxsave.mxcsr;
	} else {
		return 0x1f80;
	}
}

#if 0

void set_fpu_cwd( struct task_struct *tsk, unsigned short cwd )
{
	if ( cpu_has_fxsr ) {
		tsk->thread.i387.fxsave.cwd = cwd;
	} else {
		tsk->thread.i387.fsave.cwd = ((long)cwd | 0xffff0000u);
	}
}

void set_fpu_swd( struct task_struct *tsk, unsigned short swd )
{
	if ( cpu_has_fxsr ) {
		tsk->thread.i387.fxsave.swd = swd;
	} else {
		tsk->thread.i387.fsave.swd = ((long)swd | 0xffff0000u);
	}
}

void set_fpu_twd( struct task_struct *tsk, unsigned short twd )
{
	if ( cpu_has_fxsr ) {
		tsk->thread.i387.fxsave.twd = twd_i387_to_fxsr(twd);
	} else {
		tsk->thread.i387.fsave.twd = ((long)twd | 0xffff0000u);
	}
}

#endif  /*  0  */

/*
 * FXSR floating point environment conversions.
 */

static int convert_fxsr_to_user( struct _fpstate __user *buf,
					struct i387_fxsave_struct *fxsave )
{
	unsigned long env[7];
	struct _fpreg __user *to;
	struct _fpxreg *from;
	int i;

	env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
	env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
	env[2] = twd_fxsr_to_i387(fxsave);
	env[3] = fxsave->fip;
	env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
	env[5] = fxsave->foo;
	env[6] = fxsave->fos;

	if ( __copy_to_user( buf, env, 7 * sizeof(unsigned long) ) )
		return 1;

	to = &buf->_st[0];
	from = (struct _fpxreg *) &fxsave->st_space[0];
	for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
		unsigned long __user *t = (unsigned long __user *)to;
		unsigned long *f = (unsigned long *)from;

		if (__put_user(*f, t) ||
				__put_user(*(f + 1), t + 1) ||
				__put_user(from->exponent, &to->exponent))
			return 1;
	}
	return 0;
}

static int convert_fxsr_from_user( struct i387_fxsave_struct *fxsave,
					  struct _fpstate __user *buf )
{
	unsigned long env[7];
	struct _fpxreg *to;
	struct _fpreg __user *from;
	int i;

	if ( __copy_from_user( env, buf, 7 * sizeof(long) ) )
		return 1;

	fxsave->cwd = (unsigned short)(env[0] & 0xffff);
	fxsave->swd = (unsigned short)(env[1] & 0xffff);
	fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
	fxsave->fip = env[3];
	fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
	fxsave->fcs = (env[4] & 0xffff);
	fxsave->foo = env[5];
	fxsave->fos = env[6];

	to = (struct _fpxreg *) &fxsave->st_space[0];
	from = &buf->_st[0];
	for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
		unsigned long *t = (unsigned long *)to;
		unsigned long __user *f = (unsigned long __user *)from;

		if (__get_user(*t, f) ||
				__get_user(*(t + 1), f + 1) ||
				__get_user(to->exponent, &from->exponent))
			return 1;
	}
	return 0;
}

/*
 * Signal frame handlers.
 */

static inline int save_i387_fsave( struct _fpstate __user *buf )
{
	struct task_struct *tsk = current;

	unlazy_fpu( tsk );
	tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
	if ( __copy_to_user( buf, &tsk->thread.i387.fsave,
			     sizeof(struct i387_fsave_struct) ) )
		return -1;
	return 1;
}

static int save_i387_fxsave( struct _fpstate __user *buf )
{
	struct task_struct *tsk = current;
	int err = 0;

	unlazy_fpu( tsk );

	if ( convert_fxsr_to_user( buf, &tsk->thread.i387.fxsave ) )
		return -1;

	err |= __put_user( tsk->thread.i387.fxsave.swd, &buf->status );
	err |= __put_user( X86_FXSR_MAGIC, &buf->magic );
	if ( err )
		return -1;

	if ( __copy_to_user( &buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
			     sizeof(struct i387_fxsave_struct) ) )
		return -1;
	return 1;
}

int save_i387( struct _fpstate __user *buf )
{
	if ( !used_math() )
		return 0;

	/* This will cause a "finit" to be triggered by the next
	 * attempted FPU operation by the 'current' process.
	 */
	clear_used_math();

	if ( HAVE_HWFP ) {
		if ( cpu_has_fxsr ) {
			return save_i387_fxsave( buf );
		} else {
			return save_i387_fsave( buf );
		}
	} else {
		return save_i387_soft( &current->thread.i387.soft, buf );
	}
}

static inline int restore_i387_fsave( struct _fpstate __user *buf )
{
	struct task_struct *tsk = current;
	clear_fpu( tsk );
	return __copy_from_user( &tsk->thread.i387.fsave, buf,
				 sizeof(struct i387_fsave_struct) );
}

static int restore_i387_fxsave( struct _fpstate __user *buf )
{
	int err;
	struct task_struct *tsk = current;
	clear_fpu( tsk );
	err = __copy_from_user( &tsk->thread.i387.fxsave, &buf->_fxsr_env[0],
				sizeof(struct i387_fxsave_struct) );
	/* mxcsr reserved bits must be masked to zero for security reasons */
	tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
	return err ? 1 : convert_fxsr_from_user( &tsk->thread.i387.fxsave, buf );
}

int restore_i387( struct _fpstate __user *buf )
{
	int err;

	if ( HAVE_HWFP ) {
		if ( cpu_has_fxsr ) {
			err = restore_i387_fxsave( buf );
		} else {
			err = restore_i387_fsave( buf );
		}
	} else {
		err = restore_i387_soft( &current->thread.i387.soft, buf );
	}
	set_used_math();
	return err;
}

/*
 * ptrace request handlers.
 */

static inline int get_fpregs_fsave( struct user_i387_struct __user *buf,
				    struct task_struct *tsk )
{
	return __copy_to_user( buf, &tsk->thread.i387.fsave,
			       sizeof(struct user_i387_struct) );
}

static inline int get_fpregs_fxsave( struct user_i387_struct __user *buf,
				     struct task_struct *tsk )
{
	return convert_fxsr_to_user( (struct _fpstate __user *)buf,
				     &tsk->thread.i387.fxsave );
}

int get_fpregs( struct user_i387_struct __user *buf, struct task_struct *tsk )
{
	if ( HAVE_HWFP ) {
		if ( cpu_has_fxsr ) {
			return get_fpregs_fxsave( buf, tsk );
		} else {
			return get_fpregs_fsave( buf, tsk );
		}
	} else {
		return save_i387_soft( &tsk->thread.i387.soft,
				       (struct _fpstate __user *)buf );
	}
}

static inline int set_fpregs_fsave( struct task_struct *tsk,
				    struct user_i387_struct __user *buf )
{
	return __copy_from_user( &tsk->thread.i387.fsave, buf,
				 sizeof(struct user_i387_struct) );
}

static inline int set_fpregs_fxsave( struct task_struct *tsk,
				     struct user_i387_struct __user *buf )
{
	return convert_fxsr_from_user( &tsk->thread.i387.fxsave,
				       (struct _fpstate __user *)buf );
}

int set_fpregs( struct task_struct *tsk, struct user_i387_struct __user *buf )
{
	if ( HAVE_HWFP ) {
		if ( cpu_has_fxsr ) {
			return set_fpregs_fxsave( tsk, buf );
		} else {
			return set_fpregs_fsave( tsk, buf );
		}
	} else {
		return restore_i387_soft( &tsk->thread.i387.soft,
					  (struct _fpstate __user *)buf );
	}
}

int get_fpxregs( struct user_fxsr_struct __user *buf, struct task_struct *tsk )
{
	if ( cpu_has_fxsr ) {
		if (__copy_to_user( buf, &tsk->thread.i387.fxsave,
				    sizeof(struct user_fxsr_struct) ))
			return -EFAULT;
		return 0;
	} else {
		return -EIO;
	}
}

int set_fpxregs( struct task_struct *tsk, struct user_fxsr_struct __user *buf )
{
	int ret = 0;

	if ( cpu_has_fxsr ) {
		if (__copy_from_user( &tsk->thread.i387.fxsave, buf,
				  sizeof(struct user_fxsr_struct) ))
			ret = -EFAULT;
		/* mxcsr reserved bits must be masked to zero for security reasons */
		tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
	} else {
		ret = -EIO;
	}
	return ret;
}

/*
 * FPU state for core dumps.
 */

static inline void copy_fpu_fsave( struct task_struct *tsk,
				   struct user_i387_struct *fpu )
{
	memcpy( fpu, &tsk->thread.i387.fsave,
		sizeof(struct user_i387_struct) );
}

static inline void copy_fpu_fxsave( struct task_struct *tsk,
				   struct user_i387_struct *fpu )
{
	unsigned short *to;
	unsigned short *from;
	int i;

	memcpy( fpu, &tsk->thread.i387.fxsave, 7 * sizeof(long) );

	to = (unsigned short *)&fpu->st_space[0];
	from = (unsigned short *)&tsk->thread.i387.fxsave.st_space[0];
	for ( i = 0 ; i < 8 ; i++, to += 5, from += 8 ) {
		memcpy( to, from, 5 * sizeof(unsigned short) );
	}
}

int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
{
	int fpvalid;
	struct task_struct *tsk = current;

	fpvalid = !!used_math();
	if ( fpvalid ) {
		unlazy_fpu( tsk );
		if ( cpu_has_fxsr ) {
			copy_fpu_fxsave( tsk, fpu );
		} else {
			copy_fpu_fsave( tsk, fpu );
		}
	}

	return fpvalid;
}
EXPORT_SYMBOL(dump_fpu);

int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
{
	int fpvalid = !!tsk_used_math(tsk);

	if (fpvalid) {
		if (tsk == current)
			unlazy_fpu(tsk);
		if (cpu_has_fxsr)
			copy_fpu_fxsave(tsk, fpu);
		else
			copy_fpu_fsave(tsk, fpu);
	}
	return fpvalid;
}

int dump_task_extended_fpu(struct task_struct *tsk, struct user_fxsr_struct *fpu)
{
	int fpvalid = tsk_used_math(tsk) && cpu_has_fxsr;

	if (fpvalid) {
		if (tsk == current)
		       unlazy_fpu(tsk);
		memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(*fpu));
	}
	return fpvalid;
}