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,
  33                        sizeof(struct i387_fxsave_struct));
  34                 asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
  35                 mask = current->thread.i387.fxsave.mxcsr_mask;
  36                 if (mask == 0)
  37                         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,
  53                        sizeof(struct i387_fxsave_struct));
  54                 tsk->thread.i387.fxsave.cwd = 0x37f;
  55                 if (cpu_has_xmm)
  56                         tsk->thread.i387.fxsave.mxcsr = 0x1f80;
  57         } else {
  58                 memset(&tsk->thread.i387.fsave, 0,
  59                        sizeof(struct i387_fsave_struct));
  60                 tsk->thread.i387.fsave.cwd = 0xffff037fu;
  61                 tsk->thread.i387.fsave.swd = 0xffff0000u;
  62                 tsk->thread.i387.fsave.twd = 0xffffffffu;
  63                 tsk->thread.i387.fsave.fos = 0xffff0000u;
  64         }
  65         /* only the device not available exception
  66          * or ptrace can call init_fpu */
  67         set_stopped_child_used_math(tsk);
  68 }
  69
  70 /*
  71  * FPU lazy state save handling.
  72  */
  73
  74 void kernel_fpu_begin(void)
  75 {
  76         struct thread_info *thread = current_thread_info();
  77
  78         preempt_disable();
  79         if (thread->status & TS_USEDFPU) {
  80                 __save_init_fpu(thread->task);
  81                 return;
  82         }
  83         clts();
  84 }
  85 EXPORT_SYMBOL_GPL(kernel_fpu_begin);
  86
  87 /*
  88  * FPU tag word conversions.
  89  */
  90
  91 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
  92 {
  93         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
  94
  95         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
  96         tmp = ~twd;
  97         tmp = (tmp | (tmp >> 1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
  98         /* and move the valid bits to the lower byte. */
  99         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 100         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 101         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 102
 103         return tmp;
 104 }
 105
 106 static inline unsigned long twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
 107 {
 108         struct _fpxreg *st = NULL;
 109         unsigned long tos = (fxsave->swd >> 11) & 7;
 110         unsigned long twd = (unsigned long) fxsave->twd;
 111         unsigned long tag;
 112         unsigned long ret = 0xffff0000u;
 113         int i;
 114
 115 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16);
 116
 117         for (i = 0; i < 8; i++) {
 118                 if (twd & 0x1) {
 119                         st = FPREG_ADDR(fxsave, (i - tos) & 7);
 120
 121                         switch (st->exponent & 0x7fff) {
 122                         case 0x7fff:
 123                                 tag = 2;                /* Special */
 124                                 break;
 125                         case 0x0000:
 126                                 if (!st->significand[0] &&
 127                                     !st->significand[1] &&
 128                                     !st->significand[2] &&
 129                                     !st->significand[3]) {
 130                                         tag = 1;        /* Zero */
 131                                 } else {
 132                                         tag = 2;        /* Special */
 133                                 }
 134                                 break;
 135                         default:
 136                                 if (st->significand[3] & 0x8000) {
 137                                         tag = 0;        /* Valid */
 138                                 } else {
 139                                         tag = 2;        /* Special */
 140                                 }
 141                                 break;
 142                         }
 143                 } else {
 144                         tag = 3;                        /* Empty */
 145                 }
 146                 ret |= (tag << (2 * i));
 147                 twd = twd >> 1;
 148         }
 149         return ret;
 150 }
 151
 152 /*
 153  * FPU state interaction.
 154  */
 155
 156 unsigned short get_fpu_cwd(struct task_struct *tsk)
 157 {
 158         if (cpu_has_fxsr) {
 159                 return tsk->thread.i387.fxsave.cwd;
 160         } else {
 161                 return (unsigned short)tsk->thread.i387.fsave.cwd;
 162         }
 163 }
 164
 165 unsigned short get_fpu_swd(struct task_struct *tsk)
 166 {
 167         if (cpu_has_fxsr) {
 168                 return tsk->thread.i387.fxsave.swd;
 169         } else {
 170                 return (unsigned short)tsk->thread.i387.fsave.swd;
 171         }
 172 }
 173
 174 #if 0
 175 unsigned short get_fpu_twd(struct task_struct *tsk)
 176 {
 177         if (cpu_has_fxsr) {
 178                 return tsk->thread.i387.fxsave.twd;
 179         } else {
 180                 return (unsigned short)tsk->thread.i387.fsave.twd;
 181         }
 182 }
 183 #endif  /*  0  */
 184
 185 unsigned short get_fpu_mxcsr(struct task_struct *tsk)
 186 {
 187         if (cpu_has_xmm) {
 188                 return tsk->thread.i387.fxsave.mxcsr;
 189         } else {
 190                 return 0x1f80;
 191         }
 192 }
 193
 194 #if 0
 195
 196 void set_fpu_cwd(struct task_struct *tsk, unsigned short cwd)
 197 {
 198         if (cpu_has_fxsr) {
 199                 tsk->thread.i387.fxsave.cwd = cwd;
 200         } else {
 201                 tsk->thread.i387.fsave.cwd = ((long)cwd | 0xffff0000u);
 202         }
 203 }
 204
 205 void set_fpu_swd(struct task_struct *tsk, unsigned short swd)
 206 {
 207         if (cpu_has_fxsr) {
 208                 tsk->thread.i387.fxsave.swd = swd;
 209         } else {
 210                 tsk->thread.i387.fsave.swd = ((long)swd | 0xffff0000u);
 211         }
 212 }
 213
 214 void set_fpu_twd(struct task_struct *tsk, unsigned short twd)
 215 {
 216         if (cpu_has_fxsr) {
 217                 tsk->thread.i387.fxsave.twd = twd_i387_to_fxsr(twd);
 218         } else {
 219                 tsk->thread.i387.fsave.twd = ((long)twd | 0xffff0000u);
 220         }
 221 }
 222
 223 #endif  /*  0  */
 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(&current->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(&current->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
 472                  * for security reasons */
 473                 tsk->thread.i387.fxsave.mxcsr &= mxcsr_feature_mask;
 474         } else {
 475                 ret = -EIO;
 476         }
 477         return ret;
 478 }
 479
 480 /*
 481  * FPU state for core dumps.
 482  */
 483
 484 static inline void copy_fpu_fsave(struct task_struct *tsk,
 485                                   struct user_i387_struct *fpu)
 486 {
 487         memcpy(fpu, &tsk->thread.i387.fsave,
 488                sizeof(struct user_i387_struct));
 489 }
 490
 491 static inline void copy_fpu_fxsave(struct task_struct *tsk,
 492                                    struct user_i387_struct *fpu)
 493 {
 494         unsigned short *to;
 495         unsigned short *from;
 496         int i;
 497
 498         memcpy(fpu, &tsk->thread.i387.fxsave, 7 * sizeof(long));
 499
 500         to = (unsigned short *)&fpu->st_space[0];
 501         from = (unsigned short *)&tsk->thread.i387.fxsave.st_space[0];
 502         for (i = 0; i < 8; i++, to += 5, from += 8)
 503                 memcpy(to, from, 5 * sizeof(unsigned short));
 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 EXPORT_SYMBOL(dump_fpu);
 524
 525 int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
 526 {
 527         int fpvalid = !!tsk_used_math(tsk);
 528
 529         if (fpvalid) {
 530                 if (tsk == current)
 531                         unlazy_fpu(tsk);
 532                 if (cpu_has_fxsr)
 533                         copy_fpu_fxsave(tsk, fpu);
 534                 else
 535                         copy_fpu_fsave(tsk, fpu);
 536         }
 537         return fpvalid;
 538 }
 539
 540 int dump_task_extended_fpu(struct task_struct *tsk,
 541                            struct user_fxsr_struct *fpu)
 542 {
 543         int fpvalid = tsk_used_math(tsk) && cpu_has_fxsr;
 544
 545         if (fpvalid) {
 546                 if (tsk == current)
 547                        unlazy_fpu(tsk);
 548                 memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(*fpu));
 549         }
 550         return fpvalid;
 551 }