arch/x86/kernel/i387_32.c

   1 /*
   2  *  Copyright (C) 1994 Linus Torvalds
   3  *
   4  *  Pentium III FXSR, SSE support
   5  *  General FPU state handling cleanups
   6  *      Gareth Hughes <gareth@valinux.com>, May 2000
   7  */
   8
   9 #include <linux/sched.h>
  10 #include <linux/module.h>
  11 #include <asm/processor.h>
  12 #include <asm/i387.h>
  13 #include <asm/math_emu.h>
  14 #include <asm/sigcontext.h>
  15 #include <asm/user.h>
  16 #include <asm/ptrace.h>
  17 #include <asm/uaccess.h>
  18
  19 #ifdef CONFIG_MATH_EMULATION
  20 #define HAVE_HWFP (boot_cpu_data.hard_math)
  21 #else
  22 #define HAVE_HWFP 1
  23 #endif
  24
  25 static unsigned long mxcsr_feature_mask __read_mostly = 0xffffffff;
  26
  27 void mxcsr_feature_mask_init(void)
  28 {
  29         unsigned long mask = 0;
  30         clts();
  31         if (cpu_has_fxsr) {
  32                 memset(&current->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
  33                 asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
  34                 mask = current->thread.i387.fxsave.mxcsr_mask;
  35                 if (mask == 0) mask = 0x0000ffbf;
  36         }
  37         mxcsr_feature_mask &= mask;
  38         stts();
  39 }
  40
  41 /*
  42  * The _current_ task is using the FPU for the first time
  43  * so initialize it and set the mxcsr to its default
  44  * value at reset if we support XMM instructions and then
  45  * remeber the current task has used the FPU.
  46  */
  47 void init_fpu(struct task_struct *tsk)
  48 {
  49         if (cpu_has_fxsr) {
  50                 memset(&tsk->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
  51                 tsk->thread.i387.fxsave.cwd = 0x37f;
  52                 if (cpu_has_xmm)
  53                         tsk->thread.i387.fxsave.mxcsr = 0x1f80;
  54         } else {
  55                 memset(&tsk->thread.i387.fsave, 0, sizeof(struct i387_fsave_struct));
  56                 tsk->thread.i387.fsave.cwd = 0xffff037fu;
  57                 tsk->thread.i387.fsave.swd = 0xffff0000u;
  58                 tsk->thread.i387.fsave.twd = 0xffffffffu;
  59                 tsk->thread.i387.fsave.fos = 0xffff0000u;
  60         }
  61         /* only the device not available exception or ptrace can call init_fpu */
  62         set_stopped_child_used_math(tsk);
  63 }
  64
  65 /*
  66  * FPU lazy state save handling.
  67  */
  68
  69 void kernel_fpu_begin(void)
  70 {
  71         struct thread_info *thread = current_thread_info();
  72
  73         preempt_disable();
  74         if (thread->status & TS_USEDFPU) {
  75                 __save_init_fpu(thread->task);
  76                 return;
  77         }
  78         clts();
  79 }
  80 EXPORT_SYMBOL_GPL(kernel_fpu_begin);
  81
  82 /*
  83  * FPU tag word conversions.
  84  */
  85
  86 static inline unsigned short twd_i387_to_fxsr( unsigned short twd )
  87 {
  88         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
  89
  90         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
  91         tmp = ~twd;
  92         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
  93         /* and move the valid bits to the lower byte. */
  94         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
  95         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
  96         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
  97         return tmp;
  98 }
  99
 100 static inline unsigned long twd_fxsr_to_i387( struct i387_fxsave_struct *fxsave )
 101 {
 102         struct _fpxreg *st = NULL;
 103         unsigned long tos = (fxsave->swd >> 11) & 7;
 104         unsigned long twd = (unsigned long) fxsave->twd;
 105         unsigned long tag;
 106         unsigned long ret = 0xffff0000u;
 107         int i;
 108
 109 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16);
 110
 111         for ( i = 0 ; i < 8 ; i++ ) {
 112                 if ( twd & 0x1 ) {
 113                         st = FPREG_ADDR( fxsave, (i - tos) & 7 );
 114
 115                         switch ( st->exponent & 0x7fff ) {
 116                         case 0x7fff:
 117                                 tag = 2;                /* Special */
 118                                 break;
 119                         case 0x0000:
 120                                 if ( !st->significand[0] &&
 121                                      !st->significand[1] &&
 122                                      !st->significand[2] &&
 123                                      !st->significand[3] ) {
 124                                         tag = 1;        /* Zero */
 125                                 } else {
 126                                         tag = 2;        /* Special */
 127                                 }
 128                                 break;
 129                         default:
 130                                 if ( st->significand[3] & 0x8000 ) {
 131                                         tag = 0;        /* Valid */
 132                                 } else {
 133                                         tag = 2;        /* Special */
 134                                 }
 135                                 break;
 136                         }
 137                 } else {
 138                         tag = 3;                        /* Empty */
 139                 }
 140                 ret |= (tag << (2 * i));
 141                 twd = twd >> 1;
 142         }
 143         return ret;
 144 }
 145
 146 /*
 147  * FPU state interaction.
 148  */
 149
 150 unsigned short get_fpu_cwd( struct task_struct *tsk )
 151 {
 152         if ( cpu_has_fxsr ) {
 153                 return tsk->thread.i387.fxsave.cwd;
 154         } else {
 155                 return (unsigned short)tsk->thread.i387.fsave.cwd;
 156         }
 157 }
 158
 159 unsigned short get_fpu_swd( struct task_struct *tsk )
 160 {
 161         if ( cpu_has_fxsr ) {
 162                 return tsk->thread.i387.fxsave.swd;
 163         } else {
 164                 return (unsigned short)tsk->thread.i387.fsave.swd;
 165         }
 166 }
 167
 168 #if 0
 169 unsigned short get_fpu_twd( struct task_struct *tsk )
 170 {
 171         if ( cpu_has_fxsr ) {
 172                 return tsk->thread.i387.fxsave.twd;
 173         } else {
 174                 return (unsigned short)tsk->thread.i387.fsave.twd;
 175         }
 176 }
 177 #endif  /*  0  */
 178
 179 unsigned short get_fpu_mxcsr( struct task_struct *tsk )
 180 {
 181         if ( cpu_has_xmm ) {
 182                 return tsk->thread.i387.fxsave.mxcsr;
 183         } else {
 184                 return 0x1f80;
 185         }
 186 }
 187
 188 #if 0
 189
 190 void set_fpu_cwd( struct task_struct *tsk, unsigned short cwd )
 191 {
 192         if ( cpu_has_fxsr ) {
 193                 tsk->thread.i387.fxsave.cwd = cwd;
 194         } else {
 195                 tsk->thread.i387.fsave.cwd = ((long)cwd | 0xffff0000u);
 196         }
 197 }
 198
 199 void set_fpu_swd( struct task_struct *tsk, unsigned short swd )
 200 {
 201         if ( cpu_has_fxsr ) {
 202                 tsk->thread.i387.fxsave.swd = swd;
 203         } else {
 204                 tsk->thread.i387.fsave.swd = ((long)swd | 0xffff0000u);
 205         }
 206 }
 207
 208 void set_fpu_twd( struct task_struct *tsk, unsigned short twd )
 209 {
 210         if ( cpu_has_fxsr ) {
 211                 tsk->thread.i387.fxsave.twd = twd_i387_to_fxsr(twd);
 212         } else {
 213                 tsk->thread.i387.fsave.twd = ((long)twd | 0xffff0000u);
 214         }
 215 }
 216
 217 #endif  /*  0  */
 218
 219 /*
 220  * FXSR floating point environment conversions.
 221  */
 222
 223 static int convert_fxsr_to_user( struct _fpstate __user *buf,
 224                                         struct i387_fxsave_struct *fxsave )
 225 {
 226         unsigned long env[7];
 227         struct _fpreg __user *to;
 228         struct _fpxreg *from;
 229         int i;
 230
 231         env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
 232         env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
 233         env[2] = twd_fxsr_to_i387(fxsave);
 234         env[3] = fxsave->fip;
 235         env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
 236         env[5] = fxsave->foo;
 237         env[6] = fxsave->fos;
 238
 239         if ( __copy_to_user( buf, env, 7 * sizeof(unsigned long) ) )
 240                 return 1;
 241
 242         to = &buf->_st[0];
 243         from = (struct _fpxreg *) &fxsave->st_space[0];
 244         for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
 245                 unsigned long __user *t = (unsigned long __user *)to;
 246                 unsigned long *f = (unsigned long *)from;
 247
 248                 if (__put_user(*f, t) ||
 249                                 __put_user(*(f + 1), t + 1) ||
 250                                 __put_user(from->exponent, &to->exponent))
 251                         return 1;
 252         }
 253         return 0;
 254 }
 255
 256 static int convert_fxsr_from_user( struct i387_fxsave_struct *fxsave,
 257                                           struct _fpstate __user *buf )
 258 {
 259         unsigned long env[7];
 260         struct _fpxreg *to;
 261         struct _fpreg __user *from;
 262         int i;
 263
 264         if ( __copy_from_user( env, buf, 7 * sizeof(long) ) )
 265                 return 1;
 266
 267         fxsave->cwd = (unsigned short)(env[0] & 0xffff);
 268         fxsave->swd = (unsigned short)(env[1] & 0xffff);
 269         fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
 270         fxsave->fip = env[3];
 271         fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
 272         fxsave->fcs = (env[4] & 0xffff);
 273         fxsave->foo = env[5];
 274         fxsave->fos = env[6];
 275
 276         to = (struct _fpxreg *) &fxsave->st_space[0];
 277         from = &buf->_st[0];
 278         for ( i = 0 ; i < 8 ; i++, to++, from++ ) {
 279                 unsigned long *t = (unsigned long *)to;
 280                 unsigned long __user *f = (unsigned long __user *)from;
 281
 282                 if (__get_user(*t, f) ||
 283                                 __get_user(*(t + 1), f + 1) ||
 284                                 __get_user(to->exponent, &from->exponent))
 285                         return 1;
 286         }
 287         return 0;
 288 }
 289
 290 /*
 291  * Signal frame handlers.
 292  */
 293
 294 static inline int save_i387_fsave( struct _fpstate __user *buf )
 295 {
 296         struct task_struct *tsk = current;
 297
 298         unlazy_fpu( tsk );
 299         tsk->thread.i387.fsave.status = tsk->thread.i387.fsave.swd;
 300         if ( __copy_to_user( buf, &tsk->thread.i387.fsave,
 301                              sizeof(struct i387_fsave_struct) ) )
 302                 return -1;
 303         return 1;
 304 }
 305
 306 static int save_i387_fxsave( struct _fpstate __user *buf )
 307 {
 308         struct task_struct *tsk = current;
 309         int err = 0;
 310
 311         unlazy_fpu( tsk );
 312
 313         if ( convert_fxsr_to_user( buf, &tsk->thread.i387.fxsave ) )
 314                 return -1;
 315
 316         err |= __put_user( tsk->thread.i387.fxsave.swd, &buf->status );
 317         err |= __put_user( X86_FXSR_MAGIC, &buf->magic );
 318         if ( err )
 319                 return -1;
 320
 321         if ( __copy_to_user( &buf->_fxsr_env[0], &tsk->thread.i387.fxsave,
 322                              sizeof(struct i387_fxsave_struct) ) )
 323                 return -1;
 324         return 1;
 325 }
 326
 327 int save_i387( struct _fpstate __user *buf )
 328 {
 329         if ( !used_math() )
 330                 return 0;
 331
 332         /* This will cause a "finit" to be triggered by the next
 333          * attempted FPU operation by the 'current' process.
 334          */
 335         clear_used_math();
 336
 337         if ( HAVE_HWFP ) {
 338                 if ( cpu_has_fxsr ) {
 339                         return save_i387_fxsave( buf );
 340                 } else {
 341                         return save_i387_fsave( buf );
 342                 }
 343         } else {
 344                 return save_i387_soft( &current->thread.i387.soft, buf );
 345         }
 346 }
 347
 348 static inline int restore_i387_fsave( struct _fpstate __user *buf )
 349 {
 350         struct task_struct *tsk = current;
 351         clear_fpu( tsk );
 352         return __copy_from_user( &tsk->thread.i387.fsave, buf,
 353                                  sizeof(struct i387_fsave_struct) );
 354 }
 355
 356 static int restore_i387_fxsave( struct _fpstate __user *buf )
 357 {
 358         int err;
 359         struct task_struct *tsk = current;
 360         clear_fpu( tsk );
 361         err = __copy_from_user( &tsk->thread.i387.fxsave, &buf->_fxsr_env[0],
 362                                 sizeof(struct i387_fxsave_struct) );
 363         /* mxcsr reserved bits must be masked to zero for security reasons */
 364         tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
 365         return err ? 1 : convert_fxsr_from_user( &tsk->thread.i387.fxsave, buf );
 366 }
 367
 368 int restore_i387( struct _fpstate __user *buf )
 369 {
 370         int err;
 371
 372         if ( HAVE_HWFP ) {
 373                 if ( cpu_has_fxsr ) {
 374                         err = restore_i387_fxsave( buf );
 375                 } else {
 376                         err = restore_i387_fsave( buf );
 377                 }
 378         } else {
 379                 err = restore_i387_soft( &current->thread.i387.soft, buf );
 380         }
 381         set_used_math();
 382         return err;
 383 }
 384
 385 /*
 386  * ptrace request handlers.
 387  */
 388
 389 static inline int get_fpregs_fsave( struct user_i387_struct __user *buf,
 390                                     struct task_struct *tsk )
 391 {
 392         return __copy_to_user( buf, &tsk->thread.i387.fsave,
 393                                sizeof(struct user_i387_struct) );
 394 }
 395
 396 static inline int get_fpregs_fxsave( struct user_i387_struct __user *buf,
 397                                      struct task_struct *tsk )
 398 {
 399         return convert_fxsr_to_user( (struct _fpstate __user *)buf,
 400                                      &tsk->thread.i387.fxsave );
 401 }
 402
 403 int get_fpregs( struct user_i387_struct __user *buf, struct task_struct *tsk )
 404 {
 405         if ( HAVE_HWFP ) {
 406                 if ( cpu_has_fxsr ) {
 407                         return get_fpregs_fxsave( buf, tsk );
 408                 } else {
 409                         return get_fpregs_fsave( buf, tsk );
 410                 }
 411         } else {
 412                 return save_i387_soft( &tsk->thread.i387.soft,
 413                                        (struct _fpstate __user *)buf );
 414         }
 415 }
 416
 417 static inline int set_fpregs_fsave( struct task_struct *tsk,
 418                                     struct user_i387_struct __user *buf )
 419 {
 420         return __copy_from_user( &tsk->thread.i387.fsave, buf,
 421                                  sizeof(struct user_i387_struct) );
 422 }
 423
 424 static inline int set_fpregs_fxsave( struct task_struct *tsk,
 425                                      struct user_i387_struct __user *buf )
 426 {
 427         return convert_fxsr_from_user( &tsk->thread.i387.fxsave,
 428                                        (struct _fpstate __user *)buf );
 429 }
 430
 431 int set_fpregs( struct task_struct *tsk, struct user_i387_struct __user *buf )
 432 {
 433         if ( HAVE_HWFP ) {
 434                 if ( cpu_has_fxsr ) {
 435                         return set_fpregs_fxsave( tsk, buf );
 436                 } else {
 437                         return set_fpregs_fsave( tsk, buf );
 438                 }
 439         } else {
 440                 return restore_i387_soft( &tsk->thread.i387.soft,
 441                                           (struct _fpstate __user *)buf );
 442         }
 443 }
 444
 445 int get_fpxregs( struct user_fxsr_struct __user *buf, struct task_struct *tsk )
 446 {
 447         if ( cpu_has_fxsr ) {
 448                 if (__copy_to_user( buf, &tsk->thread.i387.fxsave,
 449                                     sizeof(struct user_fxsr_struct) ))
 450                         return -EFAULT;
 451                 return 0;
 452         } else {
 453                 return -EIO;
 454         }
 455 }
 456
 457 int set_fpxregs( struct task_struct *tsk, struct user_fxsr_struct __user *buf )
 458 {
 459         int ret = 0;
 460
 461         if ( cpu_has_fxsr ) {
 462                 if (__copy_from_user( &tsk->thread.i387.fxsave, buf,
 463                                   sizeof(struct user_fxsr_struct) ))
 464                         ret = -EFAULT;
 465                 /* mxcsr reserved bits must be masked to zero for security reasons */
 466                 tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
 467         } else {
 468                 ret = -EIO;
 469         }
 470         return ret;
 471 }
 472
 473 /*
 474  * FPU state for core dumps.
 475  */
 476
 477 static inline void copy_fpu_fsave( struct task_struct *tsk,
 478                                    struct user_i387_struct *fpu )
 479 {
 480         memcpy( fpu, &tsk->thread.i387.fsave,
 481                 sizeof(struct user_i387_struct) );
 482 }
 483
 484 static inline void copy_fpu_fxsave( struct task_struct *tsk,
 485                                    struct user_i387_struct *fpu )
 486 {
 487         unsigned short *to;
 488         unsigned short *from;
 489         int i;
 490
 491         memcpy( fpu, &tsk->thread.i387.fxsave, 7 * sizeof(long) );
 492
 493         to = (unsigned short *)&fpu->st_space[0];
 494         from = (unsigned short *)&tsk->thread.i387.fxsave.st_space[0];
 495         for ( i = 0 ; i < 8 ; i++, to += 5, from += 8 ) {
 496                 memcpy( to, from, 5 * sizeof(unsigned short) );
 497         }
 498 }
 499
 500 int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
 501 {
 502         int fpvalid;
 503         struct task_struct *tsk = current;
 504
 505         fpvalid = !!used_math();
 506         if ( fpvalid ) {
 507                 unlazy_fpu( tsk );
 508                 if ( cpu_has_fxsr ) {
 509                         copy_fpu_fxsave( tsk, fpu );
 510                 } else {
 511                         copy_fpu_fsave( tsk, fpu );
 512                 }
 513         }
 514
 515         return fpvalid;
 516 }
 517 EXPORT_SYMBOL(dump_fpu);
 518
 519 int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
 520 {
 521         int fpvalid = !!tsk_used_math(tsk);
 522
 523         if (fpvalid) {
 524                 if (tsk == current)
 525                         unlazy_fpu(tsk);
 526                 if (cpu_has_fxsr)
 527                         copy_fpu_fxsave(tsk, fpu);
 528                 else
 529                         copy_fpu_fsave(tsk, fpu);
 530         }
 531         return fpvalid;
 532 }
 533
 534 int dump_task_extended_fpu(struct task_struct *tsk, struct user_fxsr_struct *fpu)
 535 {
 536         int fpvalid = tsk_used_math(tsk) && cpu_has_fxsr;
 537
 538         if (fpvalid) {
 539                 if (tsk == current)
 540                        unlazy_fpu(tsk);
 541                 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(*fpu));
 542         }
 543         return fpvalid;
 544 }