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/fpu-internal.h>
  20 #include <asm/user.h>
  21
  22 #ifdef CONFIG_X86_64
  23 # include <asm/sigcontext32.h>
  24 # include <asm/user32.h>
  25 #else
  26 # define save_i387_xstate_ia32          save_i387_xstate
  27 # define restore_i387_xstate_ia32       restore_i387_xstate
  28 # define _fpstate_ia32          _fpstate
  29 # define _xstate_ia32           _xstate
  30 # define sig_xstate_ia32_size   sig_xstate_size
  31 # define fx_sw_reserved_ia32    fx_sw_reserved
  32 # define user_i387_ia32_struct  user_i387_struct
  33 # define user32_fxsr_struct     user_fxsr_struct
  34 #endif
  35
  36 /*
  37  * Were we in an interrupt that interrupted kernel mode?
  38  *
  39  * We can do a kernel_fpu_begin/end() pair *ONLY* if that
  40  * pair does nothing at all: the thread must not have fpu (so
  41  * that we don't try to save the FPU state), and TS must
  42  * be set (so that the clts/stts pair does nothing that is
  43  * visible in the interrupted kernel thread).
  44  */
  45 static inline bool interrupted_kernel_fpu_idle(void)
  46 {
  47         return !__thread_has_fpu(current) &&
  48                 (read_cr0() & X86_CR0_TS);
  49 }
  50
  51 /*
  52  * Were we in user mode (or vm86 mode) when we were
  53  * interrupted?
  54  *
  55  * Doing kernel_fpu_begin/end() is ok if we are running
  56  * in an interrupt context from user mode - we'll just
  57  * save the FPU state as required.
  58  */
  59 static inline bool interrupted_user_mode(void)
  60 {
  61         struct pt_regs *regs = get_irq_regs();
  62         return regs && user_mode_vm(regs);
  63 }
  64
  65 /*
  66  * Can we use the FPU in kernel mode with the
  67  * whole "kernel_fpu_begin/end()" sequence?
  68  *
  69  * It's always ok in process context (ie "not interrupt")
  70  * but it is sometimes ok even from an irq.
  71  */
  72 bool irq_fpu_usable(void)
  73 {
  74         return !in_interrupt() ||
  75                 interrupted_user_mode() ||
  76                 interrupted_kernel_fpu_idle();
  77 }
  78 EXPORT_SYMBOL(irq_fpu_usable);
  79
  80 void kernel_fpu_begin(void)
  81 {
  82         struct task_struct *me = current;
  83
  84         WARN_ON_ONCE(!irq_fpu_usable());
  85         preempt_disable();
  86         if (__thread_has_fpu(me)) {
  87                 __save_init_fpu(me);
  88                 __thread_clear_has_fpu(me);
  89                 /* We do 'stts()' in kernel_fpu_end() */
  90         } else {
  91                 this_cpu_write(fpu_owner_task, NULL);
  92                 clts();
  93         }
  94 }
  95 EXPORT_SYMBOL(kernel_fpu_begin);
  96
  97 void kernel_fpu_end(void)
  98 {
  99         stts();
 100         preempt_enable();
 101 }
 102 EXPORT_SYMBOL(kernel_fpu_end);
 103
 104 void unlazy_fpu(struct task_struct *tsk)
 105 {
 106         preempt_disable();
 107         if (__thread_has_fpu(tsk)) {
 108                 __save_init_fpu(tsk);
 109                 __thread_fpu_end(tsk);
 110         } else
 111                 tsk->fpu_counter = 0;
 112         preempt_enable();
 113 }
 114 EXPORT_SYMBOL(unlazy_fpu);
 115
 116 #ifdef CONFIG_MATH_EMULATION
 117 # define HAVE_HWFP              (boot_cpu_data.hard_math)
 118 #else
 119 # define HAVE_HWFP              1
 120 #endif
 121
 122 static unsigned int             mxcsr_feature_mask __read_mostly = 0xffffffffu;
 123 unsigned int xstate_size;
 124 EXPORT_SYMBOL_GPL(xstate_size);
 125 unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32);
 126 static struct i387_fxsave_struct fx_scratch __cpuinitdata;
 127
 128 static void __cpuinit mxcsr_feature_mask_init(void)
 129 {
 130         unsigned long mask = 0;
 131
 132         clts();
 133         if (cpu_has_fxsr) {
 134                 memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
 135                 asm volatile("fxsave %0" : : "m" (fx_scratch));
 136                 mask = fx_scratch.mxcsr_mask;
 137                 if (mask == 0)
 138                         mask = 0x0000ffbf;
 139         }
 140         mxcsr_feature_mask &= mask;
 141         stts();
 142 }
 143
 144 static void __cpuinit init_thread_xstate(void)
 145 {
 146         /*
 147          * Note that xstate_size might be overwriten later during
 148          * xsave_init().
 149          */
 150
 151         if (!HAVE_HWFP) {
 152                 /*
 153                  * Disable xsave as we do not support it if i387
 154                  * emulation is enabled.
 155                  */
 156                 setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 157                 setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
 158                 xstate_size = sizeof(struct i387_soft_struct);
 159                 return;
 160         }
 161
 162         if (cpu_has_fxsr)
 163                 xstate_size = sizeof(struct i387_fxsave_struct);
 164         else
 165                 xstate_size = sizeof(struct i387_fsave_struct);
 166 }
 167
 168 /*
 169  * Called at bootup to set up the initial FPU state that is later cloned
 170  * into all processes.
 171  */
 172
 173 void __cpuinit fpu_init(void)
 174 {
 175         unsigned long cr0;
 176         unsigned long cr4_mask = 0;
 177
 178         if (cpu_has_fxsr)
 179                 cr4_mask |= X86_CR4_OSFXSR;
 180         if (cpu_has_xmm)
 181                 cr4_mask |= X86_CR4_OSXMMEXCPT;
 182         if (cr4_mask)
 183                 set_in_cr4(cr4_mask);
 184
 185         cr0 = read_cr0();
 186         cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
 187         if (!HAVE_HWFP)
 188                 cr0 |= X86_CR0_EM;
 189         write_cr0(cr0);
 190
 191         if (!smp_processor_id())
 192                 init_thread_xstate();
 193
 194         mxcsr_feature_mask_init();
 195         /* clean state in init */
 196         current_thread_info()->status = 0;
 197         clear_used_math();
 198 }
 199
 200 void fpu_finit(struct fpu *fpu)
 201 {
 202         if (!HAVE_HWFP) {
 203                 finit_soft_fpu(&fpu->state->soft);
 204                 return;
 205         }
 206
 207         if (cpu_has_fxsr) {
 208                 struct i387_fxsave_struct *fx = &fpu->state->fxsave;
 209
 210                 memset(fx, 0, xstate_size);
 211                 fx->cwd = 0x37f;
 212                 if (cpu_has_xmm)
 213                         fx->mxcsr = MXCSR_DEFAULT;
 214         } else {
 215                 struct i387_fsave_struct *fp = &fpu->state->fsave;
 216                 memset(fp, 0, xstate_size);
 217                 fp->cwd = 0xffff037fu;
 218                 fp->swd = 0xffff0000u;
 219                 fp->twd = 0xffffffffu;
 220                 fp->fos = 0xffff0000u;
 221         }
 222 }
 223 EXPORT_SYMBOL_GPL(fpu_finit);
 224
 225 /*
 226  * The _current_ task is using the FPU for the first time
 227  * so initialize it and set the mxcsr to its default
 228  * value at reset if we support XMM instructions and then
 229  * remember the current task has used the FPU.
 230  */
 231 int init_fpu(struct task_struct *tsk)
 232 {
 233         int ret;
 234
 235         if (tsk_used_math(tsk)) {
 236                 if (HAVE_HWFP && tsk == current)
 237                         unlazy_fpu(tsk);
 238                 tsk->thread.fpu.last_cpu = ~0;
 239                 return 0;
 240         }
 241
 242         /*
 243          * Memory allocation at the first usage of the FPU and other state.
 244          */
 245         ret = fpu_alloc(&tsk->thread.fpu);
 246         if (ret)
 247                 return ret;
 248
 249         fpu_finit(&tsk->thread.fpu);
 250
 251         set_stopped_child_used_math(tsk);
 252         return 0;
 253 }
 254 EXPORT_SYMBOL_GPL(init_fpu);
 255
 256 /*
 257  * The xstateregs_active() routine is the same as the fpregs_active() routine,
 258  * as the "regset->n" for the xstate regset will be updated based on the feature
 259  * capabilites supported by the xsave.
 260  */
 261 int fpregs_active(struct task_struct *target, const struct user_regset *regset)
 262 {
 263         return tsk_used_math(target) ? regset->n : 0;
 264 }
 265
 266 int xfpregs_active(struct task_struct *target, const struct user_regset *regset)
 267 {
 268         return (cpu_has_fxsr && tsk_used_math(target)) ? regset->n : 0;
 269 }
 270
 271 int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 272                 unsigned int pos, unsigned int count,
 273                 void *kbuf, void __user *ubuf)
 274 {
 275         int ret;
 276
 277         if (!cpu_has_fxsr)
 278                 return -ENODEV;
 279
 280         ret = init_fpu(target);
 281         if (ret)
 282                 return ret;
 283
 284         sanitize_i387_state(target);
 285
 286         return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 287                                    &target->thread.fpu.state->fxsave, 0, -1);
 288 }
 289
 290 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
 291                 unsigned int pos, unsigned int count,
 292                 const void *kbuf, const void __user *ubuf)
 293 {
 294         int ret;
 295
 296         if (!cpu_has_fxsr)
 297                 return -ENODEV;
 298
 299         ret = init_fpu(target);
 300         if (ret)
 301                 return ret;
 302
 303         sanitize_i387_state(target);
 304
 305         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 306                                  &target->thread.fpu.state->fxsave, 0, -1);
 307
 308         /*
 309          * mxcsr reserved bits must be masked to zero for security reasons.
 310          */
 311         target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 312
 313         /*
 314          * update the header bits in the xsave header, indicating the
 315          * presence of FP and SSE state.
 316          */
 317         if (cpu_has_xsave)
 318                 target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE;
 319
 320         return ret;
 321 }
 322
 323 int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 324                 unsigned int pos, unsigned int count,
 325                 void *kbuf, void __user *ubuf)
 326 {
 327         int ret;
 328
 329         if (!cpu_has_xsave)
 330                 return -ENODEV;
 331
 332         ret = init_fpu(target);
 333         if (ret)
 334                 return ret;
 335
 336         /*
 337          * Copy the 48bytes defined by the software first into the xstate
 338          * memory layout in the thread struct, so that we can copy the entire
 339          * xstateregs to the user using one user_regset_copyout().
 340          */
 341         memcpy(&target->thread.fpu.state->fxsave.sw_reserved,
 342                xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
 343
 344         /*
 345          * Copy the xstate memory layout.
 346          */
 347         ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 348                                   &target->thread.fpu.state->xsave, 0, -1);
 349         return ret;
 350 }
 351
 352 int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 353                   unsigned int pos, unsigned int count,
 354                   const void *kbuf, const void __user *ubuf)
 355 {
 356         int ret;
 357         struct xsave_hdr_struct *xsave_hdr;
 358
 359         if (!cpu_has_xsave)
 360                 return -ENODEV;
 361
 362         ret = init_fpu(target);
 363         if (ret)
 364                 return ret;
 365
 366         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 367                                  &target->thread.fpu.state->xsave, 0, -1);
 368
 369         /*
 370          * mxcsr reserved bits must be masked to zero for security reasons.
 371          */
 372         target->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 373
 374         xsave_hdr = &target->thread.fpu.state->xsave.xsave_hdr;
 375
 376         xsave_hdr->xstate_bv &= pcntxt_mask;
 377         /*
 378          * These bits must be zero.
 379          */
 380         xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
 381
 382         return ret;
 383 }
 384
 385 #if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
 386
 387 /*
 388  * FPU tag word conversions.
 389  */
 390
 391 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
 392 {
 393         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 394
 395         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
 396         tmp = ~twd;
 397         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
 398         /* and move the valid bits to the lower byte. */
 399         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 400         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 401         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 402
 403         return tmp;
 404 }
 405
 406 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16)
 407 #define FP_EXP_TAG_VALID        0
 408 #define FP_EXP_TAG_ZERO         1
 409 #define FP_EXP_TAG_SPECIAL      2
 410 #define FP_EXP_TAG_EMPTY        3
 411
 412 static inline u32 twd_fxsr_to_i387(struct i387_fxsave_struct *fxsave)
 413 {
 414         struct _fpxreg *st;
 415         u32 tos = (fxsave->swd >> 11) & 7;
 416         u32 twd = (unsigned long) fxsave->twd;
 417         u32 tag;
 418         u32 ret = 0xffff0000u;
 419         int i;
 420
 421         for (i = 0; i < 8; i++, twd >>= 1) {
 422                 if (twd & 0x1) {
 423                         st = FPREG_ADDR(fxsave, (i - tos) & 7);
 424
 425                         switch (st->exponent & 0x7fff) {
 426                         case 0x7fff:
 427                                 tag = FP_EXP_TAG_SPECIAL;
 428                                 break;
 429                         case 0x0000:
 430                                 if (!st->significand[0] &&
 431                                     !st->significand[1] &&
 432                                     !st->significand[2] &&
 433                                     !st->significand[3])
 434                                         tag = FP_EXP_TAG_ZERO;
 435                                 else
 436                                         tag = FP_EXP_TAG_SPECIAL;
 437                                 break;
 438                         default:
 439                                 if (st->significand[3] & 0x8000)
 440                                         tag = FP_EXP_TAG_VALID;
 441                                 else
 442                                         tag = FP_EXP_TAG_SPECIAL;
 443                                 break;
 444                         }
 445                 } else {
 446                         tag = FP_EXP_TAG_EMPTY;
 447                 }
 448                 ret |= tag << (2 * i);
 449         }
 450         return ret;
 451 }
 452
 453 /*
 454  * FXSR floating point environment conversions.
 455  */
 456
 457 static void
 458 convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
 459 {
 460         struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
 461         struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
 462         struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
 463         int i;
 464
 465         env->cwd = fxsave->cwd | 0xffff0000u;
 466         env->swd = fxsave->swd | 0xffff0000u;
 467         env->twd = twd_fxsr_to_i387(fxsave);
 468
 469 #ifdef CONFIG_X86_64
 470         env->fip = fxsave->rip;
 471         env->foo = fxsave->rdp;
 472         /*
 473          * should be actually ds/cs at fpu exception time, but
 474          * that information is not available in 64bit mode.
 475          */
 476         env->fcs = task_pt_regs(tsk)->cs;
 477         if (tsk == current) {
 478                 savesegment(ds, env->fos);
 479         } else {
 480                 env->fos = tsk->thread.ds;
 481         }
 482         env->fos |= 0xffff0000;
 483 #else
 484         env->fip = fxsave->fip;
 485         env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
 486         env->foo = fxsave->foo;
 487         env->fos = fxsave->fos;
 488 #endif
 489
 490         for (i = 0; i < 8; ++i)
 491                 memcpy(&to[i], &from[i], sizeof(to[0]));
 492 }
 493
 494 static void convert_to_fxsr(struct task_struct *tsk,
 495                             const struct user_i387_ia32_struct *env)
 496
 497 {
 498         struct i387_fxsave_struct *fxsave = &tsk->thread.fpu.state->fxsave;
 499         struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
 500         struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
 501         int i;
 502
 503         fxsave->cwd = env->cwd;
 504         fxsave->swd = env->swd;
 505         fxsave->twd = twd_i387_to_fxsr(env->twd);
 506         fxsave->fop = (u16) ((u32) env->fcs >> 16);
 507 #ifdef CONFIG_X86_64
 508         fxsave->rip = env->fip;
 509         fxsave->rdp = env->foo;
 510         /* cs and ds ignored */
 511 #else
 512         fxsave->fip = env->fip;
 513         fxsave->fcs = (env->fcs & 0xffff);
 514         fxsave->foo = env->foo;
 515         fxsave->fos = env->fos;
 516 #endif
 517
 518         for (i = 0; i < 8; ++i)
 519                 memcpy(&to[i], &from[i], sizeof(from[0]));
 520 }
 521
 522 int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 523                unsigned int pos, unsigned int count,
 524                void *kbuf, void __user *ubuf)
 525 {
 526         struct user_i387_ia32_struct env;
 527         int ret;
 528
 529         ret = init_fpu(target);
 530         if (ret)
 531                 return ret;
 532
 533         if (!HAVE_HWFP)
 534                 return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 535
 536         if (!cpu_has_fxsr) {
 537                 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 538                                            &target->thread.fpu.state->fsave, 0,
 539                                            -1);
 540         }
 541
 542         sanitize_i387_state(target);
 543
 544         if (kbuf && pos == 0 && count == sizeof(env)) {
 545                 convert_from_fxsr(kbuf, target);
 546                 return 0;
 547         }
 548
 549         convert_from_fxsr(&env, target);
 550
 551         return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 552 }
 553
 554 int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 555                unsigned int pos, unsigned int count,
 556                const void *kbuf, const void __user *ubuf)
 557 {
 558         struct user_i387_ia32_struct env;
 559         int ret;
 560
 561         ret = init_fpu(target);
 562         if (ret)
 563                 return ret;
 564
 565         sanitize_i387_state(target);
 566
 567         if (!HAVE_HWFP)
 568                 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 569
 570         if (!cpu_has_fxsr) {
 571                 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 572                                           &target->thread.fpu.state->fsave, 0, -1);
 573         }
 574
 575         if (pos > 0 || count < sizeof(env))
 576                 convert_from_fxsr(&env, target);
 577
 578         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 579         if (!ret)
 580                 convert_to_fxsr(target, &env);
 581
 582         /*
 583          * update the header bit in the xsave header, indicating the
 584          * presence of FP.
 585          */
 586         if (cpu_has_xsave)
 587                 target->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FP;
 588         return ret;
 589 }
 590
 591 /*
 592  * Signal frame handlers.
 593  */
 594
 595 static inline int save_i387_fsave(struct _fpstate_ia32 __user *buf)
 596 {
 597         struct task_struct *tsk = current;
 598         struct i387_fsave_struct *fp = &tsk->thread.fpu.state->fsave;
 599
 600         fp->status = fp->swd;
 601         if (__copy_to_user(buf, fp, sizeof(struct i387_fsave_struct)))
 602                 return -1;
 603         return 1;
 604 }
 605
 606 static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
 607 {
 608         struct task_struct *tsk = current;
 609         struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
 610         struct user_i387_ia32_struct env;
 611         int err = 0;
 612
 613         convert_from_fxsr(&env, tsk);
 614         if (__copy_to_user(buf, &env, sizeof(env)))
 615                 return -1;
 616
 617         err |= __put_user(fx->swd, &buf->status);
 618         err |= __put_user(X86_FXSR_MAGIC, &buf->magic);
 619         if (err)
 620                 return -1;
 621
 622         if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))
 623                 return -1;
 624         return 1;
 625 }
 626
 627 static int save_i387_xsave(void __user *buf)
 628 {
 629         struct task_struct *tsk = current;
 630         struct _fpstate_ia32 __user *fx = buf;
 631         int err = 0;
 632
 633
 634         sanitize_i387_state(tsk);
 635
 636         /*
 637          * For legacy compatible, we always set FP/SSE bits in the bit
 638          * vector while saving the state to the user context.
 639          * This will enable us capturing any changes(during sigreturn) to
 640          * the FP/SSE bits by the legacy applications which don't touch
 641          * xstate_bv in the xsave header.
 642          *
 643          * xsave aware applications can change the xstate_bv in the xsave
 644          * header as well as change any contents in the memory layout.
 645          * xrestore as part of sigreturn will capture all the changes.
 646          */
 647         tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv |= XSTATE_FPSSE;
 648
 649         if (save_i387_fxsave(fx) < 0)
 650                 return -1;
 651
 652         err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,
 653                              sizeof(struct _fpx_sw_bytes));
 654         err |= __put_user(FP_XSTATE_MAGIC2,
 655                           (__u32 __user *) (buf + sig_xstate_ia32_size
 656                                             - FP_XSTATE_MAGIC2_SIZE));
 657         if (err)
 658                 return -1;
 659
 660         return 1;
 661 }
 662
 663 int save_i387_xstate_ia32(void __user *buf)
 664 {
 665         struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
 666         struct task_struct *tsk = current;
 667
 668         if (!used_math())
 669                 return 0;
 670
 671         if (!access_ok(VERIFY_WRITE, buf, sig_xstate_ia32_size))
 672                 return -EACCES;
 673         /*
 674          * This will cause a "finit" to be triggered by the next
 675          * attempted FPU operation by the 'current' process.
 676          */
 677         clear_used_math();
 678
 679         if (!HAVE_HWFP) {
 680                 return fpregs_soft_get(current, NULL,
 681                                        0, sizeof(struct user_i387_ia32_struct),
 682                                        NULL, fp) ? -1 : 1;
 683         }
 684
 685         unlazy_fpu(tsk);
 686
 687         if (cpu_has_xsave)
 688                 return save_i387_xsave(fp);
 689         if (cpu_has_fxsr)
 690                 return save_i387_fxsave(fp);
 691         else
 692                 return save_i387_fsave(fp);
 693 }
 694
 695 static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
 696 {
 697         struct task_struct *tsk = current;
 698
 699         return __copy_from_user(&tsk->thread.fpu.state->fsave, buf,
 700                                 sizeof(struct i387_fsave_struct));
 701 }
 702
 703 static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,
 704                                unsigned int size)
 705 {
 706         struct task_struct *tsk = current;
 707         struct user_i387_ia32_struct env;
 708         int err;
 709
 710         err = __copy_from_user(&tsk->thread.fpu.state->fxsave, &buf->_fxsr_env[0],
 711                                size);
 712         /* mxcsr reserved bits must be masked to zero for security reasons */
 713         tsk->thread.fpu.state->fxsave.mxcsr &= mxcsr_feature_mask;
 714         if (err || __copy_from_user(&env, buf, sizeof(env)))
 715                 return 1;
 716         convert_to_fxsr(tsk, &env);
 717
 718         return 0;
 719 }
 720
 721 static int restore_i387_xsave(void __user *buf)
 722 {
 723         struct _fpx_sw_bytes fx_sw_user;
 724         struct _fpstate_ia32 __user *fx_user =
 725                         ((struct _fpstate_ia32 __user *) buf);
 726         struct i387_fxsave_struct __user *fx =
 727                 (struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];
 728         struct xsave_hdr_struct *xsave_hdr =
 729                                 &current->thread.fpu.state->xsave.xsave_hdr;
 730         u64 mask;
 731         int err;
 732
 733         if (check_for_xstate(fx, buf, &fx_sw_user))
 734                 goto fx_only;
 735
 736         mask = fx_sw_user.xstate_bv;
 737
 738         err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);
 739
 740         xsave_hdr->xstate_bv &= pcntxt_mask;
 741         /*
 742          * These bits must be zero.
 743          */
 744         xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
 745
 746         /*
 747          * Init the state that is not present in the memory layout
 748          * and enabled by the OS.
 749          */
 750         mask = ~(pcntxt_mask & ~mask);
 751         xsave_hdr->xstate_bv &= mask;
 752
 753         return err;
 754 fx_only:
 755         /*
 756          * Couldn't find the extended state information in the memory
 757          * layout. Restore the FP/SSE and init the other extended state
 758          * enabled by the OS.
 759          */
 760         xsave_hdr->xstate_bv = XSTATE_FPSSE;
 761         return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));
 762 }
 763
 764 int restore_i387_xstate_ia32(void __user *buf)
 765 {
 766         int err;
 767         struct task_struct *tsk = current;
 768         struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
 769
 770         if (HAVE_HWFP)
 771                 clear_fpu(tsk);
 772
 773         if (!buf) {
 774                 if (used_math()) {
 775                         clear_fpu(tsk);
 776                         clear_used_math();
 777                 }
 778
 779                 return 0;
 780         } else
 781                 if (!access_ok(VERIFY_READ, buf, sig_xstate_ia32_size))
 782                         return -EACCES;
 783
 784         if (!used_math()) {
 785                 err = init_fpu(tsk);
 786                 if (err)
 787                         return err;
 788         }
 789
 790         if (HAVE_HWFP) {
 791                 if (cpu_has_xsave)
 792                         err = restore_i387_xsave(buf);
 793                 else if (cpu_has_fxsr)
 794                         err = restore_i387_fxsave(fp, sizeof(struct
 795                                                            i387_fxsave_struct));
 796                 else
 797                         err = restore_i387_fsave(fp);
 798         } else {
 799                 err = fpregs_soft_set(current, NULL,
 800                                       0, sizeof(struct user_i387_ia32_struct),
 801                                       NULL, fp) != 0;
 802         }
 803         set_used_math();
 804
 805         return err;
 806 }
 807
 808 /*
 809  * FPU state for core dumps.
 810  * This is only used for a.out dumps now.
 811  * It is declared generically using elf_fpregset_t (which is
 812  * struct user_i387_struct) but is in fact only used for 32-bit
 813  * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
 814  */
 815 int dump_fpu(struct pt_regs *regs, struct user_i387_struct *fpu)
 816 {
 817         struct task_struct *tsk = current;
 818         int fpvalid;
 819
 820         fpvalid = !!used_math();
 821         if (fpvalid)
 822                 fpvalid = !fpregs_get(tsk, NULL,
 823                                       0, sizeof(struct user_i387_ia32_struct),
 824                                       fpu, NULL);
 825
 826         return fpvalid;
 827 }
 828 EXPORT_SYMBOL(dump_fpu);
 829
 830 #endif  /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */