arch/x86/kernel/i387.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 #include <linux/module.h>
   9 #include <linux/regset.h>
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12
  13 #include <asm/sigcontext.h>
  14 #include <asm/processor.h>
  15 #include <asm/math_emu.h>
  16 #include <asm/uaccess.h>
  17 #include <asm/ptrace.h>
  18 #include <asm/i387.h>
  19 #include <asm/user.h>
  20
  21 #ifdef CONFIG_X86_64
  22 # include <asm/sigcontext32.h>
  23 # include <asm/user32.h>
  24 #else
  25 # define save_i387_xstate_ia32          save_i387_xstate
  26 # define restore_i387_xstate_ia32       restore_i387_xstate
  27 # define _fpstate_ia32          _fpstate
  28 # define _xstate_ia32           _xstate
  29 # define sig_xstate_ia32_size   sig_xstate_size
  30 # define fx_sw_reserved_ia32    fx_sw_reserved
  31 # define user_i387_ia32_struct  user_i387_struct
  32 # define user32_fxsr_struct     user_fxsr_struct
  33 #endif
  34
  35 #ifdef CONFIG_MATH_EMULATION
  36 # define HAVE_HWFP              (boot_cpu_data.hard_math)
  37 #else
  38 # define HAVE_HWFP              1
  39 #endif
  40
  41 static unsigned int             mxcsr_feature_mask __read_mostly = 0xffffffffu;
  42 unsigned int xstate_size;
  43 EXPORT_SYMBOL_GPL(xstate_size);
  44 unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32);
  45 static struct i387_fxsave_struct fx_scratch __cpuinitdata;
  46
  47 void __cpuinit mxcsr_feature_mask_init(void)
  48 {
  49         unsigned long mask = 0;
  50
  51         clts();
  52         if (cpu_has_fxsr) {
  53                 memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
  54                 asm volatile("fxsave %0" : : "m" (fx_scratch));
  55                 mask = fx_scratch.mxcsr_mask;
  56                 if (mask == 0)
  57                         mask = 0x0000ffbf;
  58         }
  59         mxcsr_feature_mask &= mask;
  60         stts();
  61 }
  62
  63 static void __cpuinit init_thread_xstate(void)
  64 {
  65         /*
  66          * Note that xstate_size might be overwriten later during
  67          * xsave_init().
  68          */
  69
  70         if (!HAVE_HWFP) {
  71                 /*
  72                  * Disable xsave as we do not support it if i387
  73                  * emulation is enabled.
  74                  */
  75                 setup_clear_cpu_cap(X86_FEATURE_XSAVE);
  76                 setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
  77                 xstate_size = sizeof(struct i387_soft_struct);
  78                 return;
  79         }
  80
  81         if (cpu_has_fxsr)
  82                 xstate_size = sizeof(struct i387_fxsave_struct);
  83         else
  84                 xstate_size = sizeof(struct i387_fsave_struct);
  85 }
  86
  87 /*
  88  * Called at bootup to set up the initial FPU state that is later cloned
  89  * into all processes.
  90  */
  91
  92 void __cpuinit fpu_init(void)
  93 {
  94         unsigned long cr0;
  95         unsigned long cr4_mask = 0;
  96
  97         if (cpu_has_fxsr)
  98                 cr4_mask |= X86_CR4_OSFXSR;
  99         if (cpu_has_xmm)
 100                 cr4_mask |= X86_CR4_OSXMMEXCPT;
 101         if (cr4_mask)
 102                 set_in_cr4(cr4_mask);
 103
 104         cr0 = read_cr0();
 105         cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
 106         if (!HAVE_HWFP)
 107                 cr0 |= X86_CR0_EM;
 108         write_cr0(cr0);
 109
 110         if (!smp_processor_id())
 111                 init_thread_xstate();
 112
 113         mxcsr_feature_mask_init();
 114         /* clean state in init */
 115         current_thread_info()->status = 0;
 116         clear_used_math();
 117 }
 118
 119 void fpu_finit(struct fpu *fpu)
 120 {
 121         if (!HAVE_HWFP) {
 122                 finit_soft_fpu(&fpu->state->soft);
 123                 return;
 124         }
 125
 126         if (cpu_has_fxsr) {
 127                 struct i387_fxsave_struct *fx = &fpu->state->fxsave;
 128
 129                 memset(fx, 0, xstate_size);
 130                 fx->cwd = 0x37f;
 131                 if (cpu_has_xmm)
 132                         fx->mxcsr = MXCSR_DEFAULT;
 133         } else {
 134                 struct i387_fsave_struct *fp = &fpu->state->fsave;
 135                 memset(fp, 0, xstate_size);
 136                 fp->cwd = 0xffff037fu;
 137                 fp->swd = 0xffff0000u;
 138                 fp->twd = 0xffffffffu;
 139                 fp->fos = 0xffff0000u;
 140         }
 141 }
 142 EXPORT_SYMBOL_GPL(fpu_finit);
 143
 144 /*
 145  * The _current_ task is using the FPU for the first time
 146  * so initialize it and set the mxcsr to its default
 147  * value at reset if we support XMM instructions and then
 148  * remember the current task has used the FPU.
 149  */
 150 int init_fpu(struct task_struct *tsk)
 151 {
 152         int ret;
 153
 154         if (tsk_used_math(tsk)) {
 155                 if (HAVE_HWFP && tsk == current)
 156                         unlazy_fpu(tsk);
 157                 return 0;
 158         }
 159
 160         /*
 161          * Memory allocation at the first usage of the FPU and other state.
 162          */
 163         ret = fpu_alloc(&tsk->thread.fpu);
 164         if (ret)
 165                 return ret;
 166
 167         fpu_finit(&tsk->thread.fpu);
 168
 169         set_stopped_child_used_math(tsk);
 170         return 0;
 171 }
 172 EXPORT_SYMBOL_GPL(init_fpu);
 173
 174 /*
 175  * The xstateregs_active() routine is the same as the fpregs_active() routine,
 176  * as the "regset->n" for the xstate regset will be updated based on the feature
 177  * capabilites supported by the xsave.
 178  */
 179 int fpregs_active(struct task_struct *target, const struct user_regset *regset)
 180 {
 181         return tsk_used_math(target) ? regset->n : 0;
 182 }
 183
 184 int xfpregs_active(struct task_struct *target, const struct user_regset *regset)
 185 {
 186         return (cpu_has_fxsr && tsk_used_math(target)) ? regset->n : 0;
 187 }
 188
 189 int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 190                 unsigned int pos, unsigned int count,
 191                 void *kbuf, void __user *ubuf)
 192 {
 193         int ret;
 194
 195         if (!cpu_has_fxsr)
 196                 return -ENODEV;
 197
 198         ret = init_fpu(target);
 199         if (ret)
 200                 return ret;
 201
 202         sanitize_i387_state(target);
 203
 204         return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 205                                    &target->thread.fpu.state->fxsave, 0, -1);
 206 }
 207
 208 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
 209                 unsigned int pos, unsigned int count,
 210                 const void *kbuf, const void __user *ubuf)
 211 {
 212         int ret;
 213
 214         if (!cpu_has_fxsr)
 215                 return -ENODEV;
 216
 217         ret = init_fpu(target);
 218         if (ret)
 219                 return ret;
 220
 221         sanitize_i387_state(target);
 222
 223         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 224                                  &target->thread.fpu.state->fxsave, 0, -1);
 225
 226         /*
 227          * mxcsr reserved bits must be masked to zero for security reasons.
 228          */
 229         target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 230
 231         /*
 232          * update the header bits in the xsave header, indicating the
 233          * presence of FP and SSE state.
 234          */
 235         if (cpu_has_xsave)
 236                 target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE;
 237
 238         return ret;
 239 }
 240
 241 int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 242                 unsigned int pos, unsigned int count,
 243                 void *kbuf, void __user *ubuf)
 244 {
 245         int ret;
 246
 247         if (!cpu_has_xsave)
 248                 return -ENODEV;
 249
 250         ret = init_fpu(target);
 251         if (ret)
 252                 return ret;
 253
 254         /*
 255          * Copy the 48bytes defined by the software first into the xstate
 256          * memory layout in the thread struct, so that we can copy the entire
 257          * xstateregs to the user using one user_regset_copyout().
 258          */
 259         memcpy(&target->thread.fpu.state->fxsave.sw_reserved,
 260                xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
 261
 262         /*
 263          * Copy the xstate memory layout.
 264          */
 265         ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 266                                   &target->thread.fpu.state->xsave, 0, -1);
 267         return ret;
 268 }
 269
 270 int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 271                   unsigned int pos, unsigned int count,
 272                   const void *kbuf, const void __user *ubuf)
 273 {
 274         int ret;
 275         struct xsave_hdr_struct *xsave_hdr;
 276
 277         if (!cpu_has_xsave)
 278                 return -ENODEV;
 279
 280         ret = init_fpu(target);
 281         if (ret)
 282                 return ret;
 283
 284         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 285                                  &target->thread.fpu.state->xsave, 0, -1);
 286
 287         /*
 288          * mxcsr reserved bits must be masked to zero for security reasons.
 289          */
 290         target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 291
 292         xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr;
 293
 294         xsave_hdr->xstate_bv &= pcntxt_mask;
 295         /*
 296          * These bits must be zero.
 297          */
 298         xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
 299
 300         return ret;
 301 }
 302
 303 #if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
 304
 305 /*
 306  * FPU tag word conversions.
 307  */
 308
 309 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
 310 {
 311         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 312
 313         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
 314         tmp = ~twd;
 315         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
 316         /* and move the valid bits to the lower byte. */
 317         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 318         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 319         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 320
 321         return tmp;
 322 }
 323
 324 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16);
 325 #define FP_EXP_TAG_VALID        0
 326 #define FP_EXP_TAG_ZERO         1
 327 #define FP_EXP_TAG_SPECIAL      2
 328 #define FP_EXP_TAG_EMPTY        3
 329
 330 static inline u32 twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
 331 {
 332         struct _fpxreg *st;
 333         u32 tos = (fxsave->swd >> 11) & 7;
 334         u32 twd = (unsigned long) fxsave->twd;
 335         u32 tag;
 336         u32 ret = 0xffff0000u;
 337         int i;
 338
 339         for (i = 0; i < 8; i++, twd >>= 1) {
 340                 if (twd & 0x1) {
 341                         st = FPREG_ADDR(fxsave, (i - tos) & 7);
 342
 343                         switch (st->exponent & 0x7fff) {
 344                         case 0x7fff:
 345                                 tag = FP_EXP_TAG_SPECIAL;
 346                                 break;
 347                         case 0x0000:
 348                                 if (!st->significand[0] &&
 349                                     !st->significand[1] &&
 350                                     !st->significand[2] &&
 351                                     !st->significand[3])
 352                                         tag = FP_EXP_TAG_ZERO;
 353                                 else
 354                                         tag = FP_EXP_TAG_SPECIAL;
 355                                 break;
 356                         default:
 357                                 if (st->significand[3] & 0x8000)
 358                                         tag = FP_EXP_TAG_VALID;
 359                                 else
 360                                         tag = FP_EXP_TAG_SPECIAL;
 361                                 break;
 362                         }
 363                 } else {
 364                         tag = FP_EXP_TAG_EMPTY;
 365                 }
 366                 ret |= tag << (2 * i);
 367         }
 368         return ret;
 369 }
 370
 371 /*
 372  * FXSR floating point environment conversions.
 373  */
 374
 375 static void
 376 convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
 377 {
 378         struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
 379         struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
 380         struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
 381         int i;
 382
 383         env->cwd = fxsave->cwd | 0xffff0000u;
 384         env->swd = fxsave->swd | 0xffff0000u;
 385         env->twd = twd_fxsr_to_i387(fxsave);
 386
 387 #ifdef CONFIG_X86_64
 388         env->fip = fxsave->rip;
 389         env->foo = fxsave->rdp;
 390         /*
 391          * should be actually ds/cs at fpu exception time, but
 392          * that information is not available in 64bit mode.
 393          */
 394         env->fcs = task_pt_regs(tsk)->cs;
 395         if (tsk == current) {
 396                 savesegment(ds, env->fos);
 397         } else {
 398                 env->fos = tsk->thread.ds;
 399         }
 400         env->fos |= 0xffff0000;
 401 #else
 402         env->fip = fxsave->fip;
 403         env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
 404         env->foo = fxsave->foo;
 405         env->fos = fxsave->fos;
 406 #endif
 407
 408         for (i = 0; i < 8; ++i)
 409                 memcpy(&to[i], &from[i], sizeof(to[0]));
 410 }
 411
 412 static void convert_to_fxsr(struct task_struct *tsk,
 413                             const struct user_i387_ia32_struct *env)
 414
 415 {
 416         struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
 417         struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
 418         struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
 419         int i;
 420
 421         fxsave->cwd = env->cwd;
 422         fxsave->swd = env->swd;
 423         fxsave->twd = twd_i387_to_fxsr(env->twd);
 424         fxsave->fop = (u16) ((u32) env->fcs >> 16);
 425 #ifdef CONFIG_X86_64
 426         fxsave->rip = env->fip;
 427         fxsave->rdp = env->foo;
 428         /* cs and ds ignored */
 429 #else
 430         fxsave->fip = env->fip;
 431         fxsave->fcs = (env->fcs & 0xffff);
 432         fxsave->foo = env->foo;
 433         fxsave->fos = env->fos;
 434 #endif
 435
 436         for (i = 0; i < 8; ++i)
 437                 memcpy(&to[i], &from[i], sizeof(from[0]));
 438 }
 439
 440 int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 441                unsigned int pos, unsigned int count,
 442                void *kbuf, void __user *ubuf)
 443 {
 444         struct user_i387_ia32_struct env;
 445         int ret;
 446
 447         ret = init_fpu(target);
 448         if (ret)
 449                 return ret;
 450
 451         if (!HAVE_HWFP)
 452                 return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 453
 454         if (!cpu_has_fxsr) {
 455                 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 456                                            &target->thread.fpu.state->fsave, 0,
 457                                            -1);
 458         }
 459
 460         sanitize_i387_state(target);
 461
 462         if (kbuf && pos == 0 && count == sizeof(env)) {
 463                 convert_from_fxsr(kbuf, target);
 464                 return 0;
 465         }
 466
 467         convert_from_fxsr(&env, target);
 468
 469         return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 470 }
 471
 472 int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 473                unsigned int pos, unsigned int count,
 474                const void *kbuf, const void __user *ubuf)
 475 {
 476         struct user_i387_ia32_struct env;
 477         int ret;
 478
 479         ret = init_fpu(target);
 480         if (ret)
 481                 return ret;
 482
 483         sanitize_i387_state(target);
 484
 485         if (!HAVE_HWFP)
 486                 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 487
 488         if (!cpu_has_fxsr) {
 489                 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 490                                           &target->thread.fpu.state->fsave, 0, -1);
 491         }
 492
 493         if (pos > 0 || count < sizeof(env))
 494                 convert_from_fxsr(&env, target);
 495
 496         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 497         if (!ret)
 498                 convert_to_fxsr(target, &env);
 499
 500         /*
 501          * update the header bit in the xsave header, indicating the
 502          * presence of FP.
 503          */
 504         if (cpu_has_xsave)
 505                 target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FP;
 506         return ret;
 507 }
 508
 509 /*
 510  * Signal frame handlers.
 511  */
 512
 513 static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
 514 {
 515         struct task_struct *tsk = current;
 516         struct i387_fsave_struct *fp = &tsk->thread.fpu.state->fsave;
 517
 518         fp->status = fp->swd;
 519         if (__copy_to_user(buf, fp, sizeof(struct i387_fsave_struct)))
 520                 return -1;
 521         return 1;
 522 }
 523
 524 static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
 525 {
 526         struct task_struct *tsk = current;
 527         struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
 528         struct user_i387_ia32_struct env;
 529         int err = 0;
 530
 531         convert_from_fxsr(&env, tsk);
 532         if (__copy_to_user(buf, &env, sizeof(env)))
 533                 return -1;
 534
 535         err |= __put_user(fx->swd, &buf->status);
 536         err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
 537         if (err)
 538                 return -1;
 539
 540         if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))
 541                 return -1;
 542         return 1;
 543 }
 544
 545 static int save_i387_xsave(void __user *buf)
 546 {
 547         struct task_struct *tsk = current;
 548         struct _fpstate_ia32 __user *fx = buf;
 549         int err = 0;
 550
 551
 552         sanitize_i387_state(tsk);
 553
 554         /*
 555          * For legacy compatible, we always set FP/SSE bits in the bit
 556          * vector while saving the state to the user context.
 557          * This will enable us capturing any changes(during sigreturn) to
 558          * the FP/SSE bits by the legacy applications which don't touch
 559          * xstate_bv in the xsave header.
 560          *
 561          * xsave aware applications can change the xstate_bv in the xsave
 562          * header as well as change any contents in the memory layout.
 563          * xrestore as part of sigreturn will capture all the changes.
 564          */
 565         tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE;
 566
 567         if (save_i387_fxsave(fx) < 0)
 568                 return -1;
 569
 570         err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,
 571                              sizeof(struct _fpx_sw_bytes));
 572         err |= __put_user(FP_XSTATE_MAGIC2,
 573                           (__u32 __user *) (buf + sig_xstate_ia32_size
 574                                             - FP_XSTATE_MAGIC2_SIZE));
 575         if (err)
 576                 return -1;
 577
 578         return 1;
 579 }
 580
 581 int save_i387_xstate_ia32(void __user *buf)
 582 {
 583         struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
 584         struct task_struct *tsk = current;
 585
 586         if (!used_math())
 587                 return 0;
 588
 589         if (!access_ok(VERIFY_WRITE, buf, sig_xstate_ia32_size))
 590                 return -EACCES;
 591         /*
 592          * This will cause a "finit" to be triggered by the next
 593          * attempted FPU operation by the 'current' process.
 594          */
 595         clear_used_math();
 596
 597         if (!HAVE_HWFP) {
 598                 return fpregs_soft_get(current, NULL,
 599                                        0, sizeof(struct user_i387_ia32_struct),
 600                                        NULL, fp) ? -1 : 1;
 601         }
 602
 603         unlazy_fpu(tsk);
 604
 605         if (cpu_has_xsave)
 606                 return save_i387_xsave(fp);
 607         if (cpu_has_fxsr)
 608                 return save_i387_fxsave(fp);
 609         else
 610                 return save_i387_fsave(fp);
 611 }
 612
 613 static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
 614 {
 615         struct task_struct *tsk = current;
 616
 617         return __copy_from_user(&tsk->thread.fpu.state->fsave, buf,
 618                                 sizeof(struct i387_fsave_struct));
 619 }
 620
 621 static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,
 622                                unsigned int size)
 623 {
 624         struct task_struct *tsk = current;
 625         struct user_i387_ia32_struct env;
 626         int err;
 627
 628         err = __copy_from_user(&tsk->thread.fpu.state->fxsave, &buf->_fxsr_env[0],
 629                                size);
 630         /* mxcsr reserved bits must be masked to zero for security reasons */
 631         tsk->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 632         if (err || __copy_from_user(&env, buf, sizeof(env)))
 633                 return 1;
 634         convert_to_fxsr(tsk, &env);
 635
 636         return 0;
 637 }
 638
 639 static int restore_i387_xsave(void __user *buf)
 640 {
 641         struct _fpx_sw_bytes fx_sw_user;
 642         struct _fpstate_ia32 __user *fx_user =
 643                         ((struct _fpstate_ia32 __user *) buf);
 644         struct i387_fxsave_struct __user *fx =
 645                 (struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];
 646         struct xsave_hdr_struct *xsave_hdr =
 647                                 &current->thread.fpu.state->xsave.xsave_hdr;
 648         u64 mask;
 649         int err;
 650
 651         if (check_for_xstate(fx, buf, &fx_sw_user))
 652                 goto fx_only;
 653
 654         mask = fx_sw_user.xstate_bv;
 655
 656         err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);
 657
 658         xsave_hdr->xstate_bv &= pcntxt_mask;
 659         /*
 660          * These bits must be zero.
 661          */
 662         xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
 663
 664         /*
 665          * Init the state that is not present in the memory layout
 666          * and enabled by the OS.
 667          */
 668         mask = ~(pcntxt_mask & ~mask);
 669         xsave_hdr->xstate_bv &= mask;
 670
 671         return err;
 672 fx_only:
 673         /*
 674          * Couldn't find the extended state information in the memory
 675          * layout. Restore the FP/SSE and init the other extended state
 676          * enabled by the OS.
 677          */
 678         xsave_hdr->xstate_bv = XSTATE_FPSSE;
 679         return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));
 680 }
 681
 682 int restore_i387_xstate_ia32(void __user *buf)
 683 {
 684         int err;
 685         struct task_struct *tsk = current;
 686         struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
 687
 688         if (HAVE_HWFP)
 689                 clear_fpu(tsk);
 690
 691         if (!buf) {
 692                 if (used_math()) {
 693                         clear_fpu(tsk);
 694                         clear_used_math();
 695                 }
 696
 697                 return 0;
 698         } else
 699                 if (!access_ok(VERIFY_READ, buf, sig_xstate_ia32_size))
 700                         return -EACCES;
 701
 702         if (!used_math()) {
 703                 err = init_fpu(tsk);
 704                 if (err)
 705                         return err;
 706         }
 707
 708         if (HAVE_HWFP) {
 709                 if (cpu_has_xsave)
 710                         err = restore_i387_xsave(buf);
 711                 else if (cpu_has_fxsr)
 712                         err = restore_i387_fxsave(fp, sizeof(struct
 713                                                            i387_fxsave_struct));
 714                 else
 715                         err = restore_i387_fsave(fp);
 716         } else {
 717                 err = fpregs_soft_set(current, NULL,
 718                                       0, sizeof(struct user_i387_ia32_struct),
 719                                       NULL, fp) != 0;
 720         }
 721         set_used_math();
 722
 723         return err;
 724 }
 725
 726 /*
 727  * FPU state for core dumps.
 728  * This is only used for a.out dumps now.
 729  * It is declared generically using elf_fpregset_t (which is
 730  * struct user_i387_struct) but is in fact only used for 32-bit
 731  * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
 732  */
 733 int dump_fpu(struct pt_regs *regs, struct user_i387_struct *fpu)
 734 {
 735         struct task_struct *tsk = current;
 736         int fpvalid;
 737
 738         fpvalid = !!used_math();
 739         if (fpvalid)
 740                 fpvalid = !fpregs_get(tsk, NULL,
 741                                       0, sizeof(struct user_i387_ia32_struct),
 742                                       fpu, NULL);
 743
 744         return fpvalid;
 745 }
 746 EXPORT_SYMBOL(dump_fpu);
 747
 748 #endif  /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */