arch/x86/kernel/fpu/xstate.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * xsave/xrstor support.
   4  *
   5  * Author: Suresh Siddha <suresh.b.siddha@intel.com>
   6  */
   7 #include <linux/compat.h>
   8 #include <linux/cpu.h>
   9 #include <linux/mman.h>
  10 #include <linux/pkeys.h>
  11 #include <linux/seq_file.h>
  12 #include <linux/proc_fs.h>
  13
  14 #include <asm/fpu/api.h>
  15 #include <asm/fpu/internal.h>
  16 #include <asm/fpu/signal.h>
  17 #include <asm/fpu/regset.h>
  18 #include <asm/fpu/xstate.h>
  19
  20 #include <asm/tlbflush.h>
  21 #include <asm/cpufeature.h>
  22
  23 /*
  24  * Although we spell it out in here, the Processor Trace
  25  * xfeature is completely unused.  We use other mechanisms
  26  * to save/restore PT state in Linux.
  27  */
  28 static const char *xfeature_names[] =
  29 {
  30         "x87 floating point registers"  ,
  31         "SSE registers"                 ,
  32         "AVX registers"                 ,
  33         "MPX bounds registers"          ,
  34         "MPX CSR"                       ,
  35         "AVX-512 opmask"                ,
  36         "AVX-512 Hi256"                 ,
  37         "AVX-512 ZMM_Hi256"             ,
  38         "Processor Trace (unused)"      ,
  39         "Protection Keys User registers",
  40         "unknown xstate feature"        ,
  41 };
  42
  43 static short xsave_cpuid_features[] __initdata = {
  44         X86_FEATURE_FPU,
  45         X86_FEATURE_XMM,
  46         X86_FEATURE_AVX,
  47         X86_FEATURE_MPX,
  48         X86_FEATURE_MPX,
  49         X86_FEATURE_AVX512F,
  50         X86_FEATURE_AVX512F,
  51         X86_FEATURE_AVX512F,
  52         X86_FEATURE_INTEL_PT,
  53         X86_FEATURE_PKU,
  54 };
  55
  56 /*
  57  * Mask of xstate features supported by the CPU and the kernel:
  58  */
  59 u64 xfeatures_mask __read_mostly;
  60
  61 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  62 static unsigned int xstate_sizes[XFEATURE_MAX]   = { [ 0 ... XFEATURE_MAX - 1] = -1};
  63 static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
  64
  65 /*
  66  * The XSAVE area of kernel can be in standard or compacted format;
  67  * it is always in standard format for user mode. This is the user
  68  * mode standard format size used for signal and ptrace frames.
  69  */
  70 unsigned int fpu_user_xstate_size;
  71
  72 /*
  73  * Return whether the system supports a given xfeature.
  74  *
  75  * Also return the name of the (most advanced) feature that the caller requested:
  76  */
  77 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
  78 {
  79         u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask;
  80
  81         if (unlikely(feature_name)) {
  82                 long xfeature_idx, max_idx;
  83                 u64 xfeatures_print;
  84                 /*
  85                  * So we use FLS here to be able to print the most advanced
  86                  * feature that was requested but is missing. So if a driver
  87                  * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
  88                  * missing AVX feature - this is the most informative message
  89                  * to users:
  90                  */
  91                 if (xfeatures_missing)
  92                         xfeatures_print = xfeatures_missing;
  93                 else
  94                         xfeatures_print = xfeatures_needed;
  95
  96                 xfeature_idx = fls64(xfeatures_print)-1;
  97                 max_idx = ARRAY_SIZE(xfeature_names)-1;
  98                 xfeature_idx = min(xfeature_idx, max_idx);
  99
 100                 *feature_name = xfeature_names[xfeature_idx];
 101         }
 102
 103         if (xfeatures_missing)
 104                 return 0;
 105
 106         return 1;
 107 }
 108 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
 109
 110 static int xfeature_is_supervisor(int xfeature_nr)
 111 {
 112         /*
 113          * We currently do not support supervisor states, but if
 114          * we did, we could find out like this.
 115          *
 116          * SDM says: If state component 'i' is a user state component,
 117          * ECX[0] return 0; if state component i is a supervisor
 118          * state component, ECX[0] returns 1.
 119          */
 120         u32 eax, ebx, ecx, edx;
 121
 122         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 123         return !!(ecx & 1);
 124 }
 125
 126 static int xfeature_is_user(int xfeature_nr)
 127 {
 128         return !xfeature_is_supervisor(xfeature_nr);
 129 }
 130
 131 /*
 132  * When executing XSAVEOPT (or other optimized XSAVE instructions), if
 133  * a processor implementation detects that an FPU state component is still
 134  * (or is again) in its initialized state, it may clear the corresponding
 135  * bit in the header.xfeatures field, and can skip the writeout of registers
 136  * to the corresponding memory layout.
 137  *
 138  * This means that when the bit is zero, the state component might still contain
 139  * some previous - non-initialized register state.
 140  *
 141  * Before writing xstate information to user-space we sanitize those components,
 142  * to always ensure that the memory layout of a feature will be in the init state
 143  * if the corresponding header bit is zero. This is to ensure that user-space doesn't
 144  * see some stale state in the memory layout during signal handling, debugging etc.
 145  */
 146 void fpstate_sanitize_xstate(struct fpu *fpu)
 147 {
 148         struct fxregs_state *fx = &fpu->state.fxsave;
 149         int feature_bit;
 150         u64 xfeatures;
 151
 152         if (!use_xsaveopt())
 153                 return;
 154
 155         xfeatures = fpu->state.xsave.header.xfeatures;
 156
 157         /*
 158          * None of the feature bits are in init state. So nothing else
 159          * to do for us, as the memory layout is up to date.
 160          */
 161         if ((xfeatures & xfeatures_mask) == xfeatures_mask)
 162                 return;
 163
 164         /*
 165          * FP is in init state
 166          */
 167         if (!(xfeatures & XFEATURE_MASK_FP)) {
 168                 fx->cwd = 0x37f;
 169                 fx->swd = 0;
 170                 fx->twd = 0;
 171                 fx->fop = 0;
 172                 fx->rip = 0;
 173                 fx->rdp = 0;
 174                 memset(&fx->st_space[0], 0, 128);
 175         }
 176
 177         /*
 178          * SSE is in init state
 179          */
 180         if (!(xfeatures & XFEATURE_MASK_SSE))
 181                 memset(&fx->xmm_space[0], 0, 256);
 182
 183         /*
 184          * First two features are FPU and SSE, which above we handled
 185          * in a special way already:
 186          */
 187         feature_bit = 0x2;
 188         xfeatures = (xfeatures_mask & ~xfeatures) >> 2;
 189
 190         /*
 191          * Update all the remaining memory layouts according to their
 192          * standard xstate layout, if their header bit is in the init
 193          * state:
 194          */
 195         while (xfeatures) {
 196                 if (xfeatures & 0x1) {
 197                         int offset = xstate_comp_offsets[feature_bit];
 198                         int size = xstate_sizes[feature_bit];
 199
 200                         memcpy((void *)fx + offset,
 201                                (void *)&init_fpstate.xsave + offset,
 202                                size);
 203                 }
 204
 205                 xfeatures >>= 1;
 206                 feature_bit++;
 207         }
 208 }
 209
 210 /*
 211  * Enable the extended processor state save/restore feature.
 212  * Called once per CPU onlining.
 213  */
 214 void fpu__init_cpu_xstate(void)
 215 {
 216         if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask)
 217                 return;
 218         /*
 219          * Make it clear that XSAVES supervisor states are not yet
 220          * implemented should anyone expect it to work by changing
 221          * bits in XFEATURE_MASK_* macros and XCR0.
 222          */
 223         WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
 224                 "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
 225
 226         xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
 227
 228         cr4_set_bits(X86_CR4_OSXSAVE);
 229         xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
 230 }
 231
 232 /*
 233  * Note that in the future we will likely need a pair of
 234  * functions here: one for user xstates and the other for
 235  * system xstates.  For now, they are the same.
 236  */
 237 static int xfeature_enabled(enum xfeature xfeature)
 238 {
 239         return !!(xfeatures_mask & (1UL << xfeature));
 240 }
 241
 242 /*
 243  * Record the offsets and sizes of various xstates contained
 244  * in the XSAVE state memory layout.
 245  */
 246 static void __init setup_xstate_features(void)
 247 {
 248         u32 eax, ebx, ecx, edx, i;
 249         /* start at the beginnning of the "extended state" */
 250         unsigned int last_good_offset = offsetof(struct xregs_state,
 251                                                  extended_state_area);
 252         /*
 253          * The FP xstates and SSE xstates are legacy states. They are always
 254          * in the fixed offsets in the xsave area in either compacted form
 255          * or standard form.
 256          */
 257         xstate_offsets[0] = 0;
 258         xstate_sizes[0] = offsetof(struct fxregs_state, xmm_space);
 259         xstate_offsets[1] = xstate_sizes[0];
 260         xstate_sizes[1] = FIELD_SIZEOF(struct fxregs_state, xmm_space);
 261
 262         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 263                 if (!xfeature_enabled(i))
 264                         continue;
 265
 266                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 267
 268                 /*
 269                  * If an xfeature is supervisor state, the offset
 270                  * in EBX is invalid. We leave it to -1.
 271                  */
 272                 if (xfeature_is_user(i))
 273                         xstate_offsets[i] = ebx;
 274
 275                 xstate_sizes[i] = eax;
 276                 /*
 277                  * In our xstate size checks, we assume that the
 278                  * highest-numbered xstate feature has the
 279                  * highest offset in the buffer.  Ensure it does.
 280                  */
 281                 WARN_ONCE(last_good_offset > xstate_offsets[i],
 282                         "x86/fpu: misordered xstate at %d\n", last_good_offset);
 283                 last_good_offset = xstate_offsets[i];
 284         }
 285 }
 286
 287 static void __init print_xstate_feature(u64 xstate_mask)
 288 {
 289         const char *feature_name;
 290
 291         if (cpu_has_xfeatures(xstate_mask, &feature_name))
 292                 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
 293 }
 294
 295 /*
 296  * Print out all the supported xstate features:
 297  */
 298 static void __init print_xstate_features(void)
 299 {
 300         print_xstate_feature(XFEATURE_MASK_FP);
 301         print_xstate_feature(XFEATURE_MASK_SSE);
 302         print_xstate_feature(XFEATURE_MASK_YMM);
 303         print_xstate_feature(XFEATURE_MASK_BNDREGS);
 304         print_xstate_feature(XFEATURE_MASK_BNDCSR);
 305         print_xstate_feature(XFEATURE_MASK_OPMASK);
 306         print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
 307         print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
 308         print_xstate_feature(XFEATURE_MASK_PKRU);
 309 }
 310
 311 /*
 312  * This check is important because it is easy to get XSTATE_*
 313  * confused with XSTATE_BIT_*.
 314  */
 315 #define CHECK_XFEATURE(nr) do {         \
 316         WARN_ON(nr < FIRST_EXTENDED_XFEATURE);  \
 317         WARN_ON(nr >= XFEATURE_MAX);    \
 318 } while (0)
 319
 320 /*
 321  * We could cache this like xstate_size[], but we only use
 322  * it here, so it would be a waste of space.
 323  */
 324 static int xfeature_is_aligned(int xfeature_nr)
 325 {
 326         u32 eax, ebx, ecx, edx;
 327
 328         CHECK_XFEATURE(xfeature_nr);
 329         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 330         /*
 331          * The value returned by ECX[1] indicates the alignment
 332          * of state component 'i' when the compacted format
 333          * of the extended region of an XSAVE area is used:
 334          */
 335         return !!(ecx & 2);
 336 }
 337
 338 /*
 339  * This function sets up offsets and sizes of all extended states in
 340  * xsave area. This supports both standard format and compacted format
 341  * of the xsave aread.
 342  */
 343 static void __init setup_xstate_comp(void)
 344 {
 345         unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8];
 346         int i;
 347
 348         /*
 349          * The FP xstates and SSE xstates are legacy states. They are always
 350          * in the fixed offsets in the xsave area in either compacted form
 351          * or standard form.
 352          */
 353         xstate_comp_offsets[0] = 0;
 354         xstate_comp_offsets[1] = offsetof(struct fxregs_state, xmm_space);
 355
 356         if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
 357                 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 358                         if (xfeature_enabled(i)) {
 359                                 xstate_comp_offsets[i] = xstate_offsets[i];
 360                                 xstate_comp_sizes[i] = xstate_sizes[i];
 361                         }
 362                 }
 363                 return;
 364         }
 365
 366         xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
 367                 FXSAVE_SIZE + XSAVE_HDR_SIZE;
 368
 369         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 370                 if (xfeature_enabled(i))
 371                         xstate_comp_sizes[i] = xstate_sizes[i];
 372                 else
 373                         xstate_comp_sizes[i] = 0;
 374
 375                 if (i > FIRST_EXTENDED_XFEATURE) {
 376                         xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
 377                                         + xstate_comp_sizes[i-1];
 378
 379                         if (xfeature_is_aligned(i))
 380                                 xstate_comp_offsets[i] =
 381                                         ALIGN(xstate_comp_offsets[i], 64);
 382                 }
 383         }
 384 }
 385
 386 /*
 387  * Print out xstate component offsets and sizes
 388  */
 389 static void __init print_xstate_offset_size(void)
 390 {
 391         int i;
 392
 393         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 394                 if (!xfeature_enabled(i))
 395                         continue;
 396                 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
 397                          i, xstate_comp_offsets[i], i, xstate_sizes[i]);
 398         }
 399 }
 400
 401 /*
 402  * All supported features have either init state all zeros or are
 403  * handled in setup_init_fpu() individually. This is an explicit
 404  * feature list and does not use XFEATURE_MASK*SUPPORTED to catch
 405  * newly added supported features at build time and make people
 406  * actually look at the init state for the new feature.
 407  */
 408 #define XFEATURES_INIT_FPSTATE_HANDLED          \
 409         (XFEATURE_MASK_FP |                     \
 410          XFEATURE_MASK_SSE |                    \
 411          XFEATURE_MASK_YMM |                    \
 412          XFEATURE_MASK_OPMASK |                 \
 413          XFEATURE_MASK_ZMM_Hi256 |              \
 414          XFEATURE_MASK_Hi16_ZMM  |              \
 415          XFEATURE_MASK_PKRU |                   \
 416          XFEATURE_MASK_BNDREGS |                \
 417          XFEATURE_MASK_BNDCSR)
 418
 419 /*
 420  * setup the xstate image representing the init state
 421  */
 422 static void __init setup_init_fpu_buf(void)
 423 {
 424         static int on_boot_cpu __initdata = 1;
 425
 426         BUILD_BUG_ON(XCNTXT_MASK != XFEATURES_INIT_FPSTATE_HANDLED);
 427
 428         WARN_ON_FPU(!on_boot_cpu);
 429         on_boot_cpu = 0;
 430
 431         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 432                 return;
 433
 434         setup_xstate_features();
 435         print_xstate_features();
 436
 437         if (boot_cpu_has(X86_FEATURE_XSAVES))
 438                 init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask;
 439
 440         /*
 441          * Init all the features state with header.xfeatures being 0x0
 442          */
 443         copy_kernel_to_xregs_booting(&init_fpstate.xsave);
 444
 445         /*
 446          * All components are now in init state. Read the state back so
 447          * that init_fpstate contains all non-zero init state. This only
 448          * works with XSAVE, but not with XSAVEOPT and XSAVES because
 449          * those use the init optimization which skips writing data for
 450          * components in init state.
 451          *
 452          * XSAVE could be used, but that would require to reshuffle the
 453          * data when XSAVES is available because XSAVES uses xstate
 454          * compaction. But doing so is a pointless exercise because most
 455          * components have an all zeros init state except for the legacy
 456          * ones (FP and SSE). Those can be saved with FXSAVE into the
 457          * legacy area. Adding new features requires to ensure that init
 458          * state is all zeroes or if not to add the necessary handling
 459          * here.
 460          */
 461         fxsave(&init_fpstate.fxsave);
 462 }
 463
 464 static int xfeature_uncompacted_offset(int xfeature_nr)
 465 {
 466         u32 eax, ebx, ecx, edx;
 467
 468         /*
 469          * Only XSAVES supports supervisor states and it uses compacted
 470          * format. Checking a supervisor state's uncompacted offset is
 471          * an error.
 472          */
 473         if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) {
 474                 WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
 475                 return -1;
 476         }
 477
 478         CHECK_XFEATURE(xfeature_nr);
 479         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 480         return ebx;
 481 }
 482
 483 static int xfeature_size(int xfeature_nr)
 484 {
 485         u32 eax, ebx, ecx, edx;
 486
 487         CHECK_XFEATURE(xfeature_nr);
 488         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 489         return eax;
 490 }
 491
 492 /*
 493  * 'XSAVES' implies two different things:
 494  * 1. saving of supervisor/system state
 495  * 2. using the compacted format
 496  *
 497  * Use this function when dealing with the compacted format so
 498  * that it is obvious which aspect of 'XSAVES' is being handled
 499  * by the calling code.
 500  */
 501 int using_compacted_format(void)
 502 {
 503         return boot_cpu_has(X86_FEATURE_XSAVES);
 504 }
 505
 506 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
 507 int validate_xstate_header(const struct xstate_header *hdr)
 508 {
 509         /* No unknown or supervisor features may be set */
 510         if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR))
 511                 return -EINVAL;
 512
 513         /* Userspace must use the uncompacted format */
 514         if (hdr->xcomp_bv)
 515                 return -EINVAL;
 516
 517         /*
 518          * If 'reserved' is shrunken to add a new field, make sure to validate
 519          * that new field here!
 520          */
 521         BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
 522
 523         /* No reserved bits may be set */
 524         if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
 525                 return -EINVAL;
 526
 527         return 0;
 528 }
 529
 530 static void __xstate_dump_leaves(void)
 531 {
 532         int i;
 533         u32 eax, ebx, ecx, edx;
 534         static int should_dump = 1;
 535
 536         if (!should_dump)
 537                 return;
 538         should_dump = 0;
 539         /*
 540          * Dump out a few leaves past the ones that we support
 541          * just in case there are some goodies up there
 542          */
 543         for (i = 0; i < XFEATURE_MAX + 10; i++) {
 544                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 545                 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
 546                         XSTATE_CPUID, i, eax, ebx, ecx, edx);
 547         }
 548 }
 549
 550 #define XSTATE_WARN_ON(x) do {                                                  \
 551         if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) {        \
 552                 __xstate_dump_leaves();                                         \
 553         }                                                                       \
 554 } while (0)
 555
 556 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do {                      \
 557         if ((nr == nr_macro) &&                                         \
 558             WARN_ONCE(sz != sizeof(__struct),                           \
 559                 "%s: struct is %zu bytes, cpu state %d bytes\n",        \
 560                 __stringify(nr_macro), sizeof(__struct), sz)) {         \
 561                 __xstate_dump_leaves();                                 \
 562         }                                                               \
 563 } while (0)
 564
 565 /*
 566  * We have a C struct for each 'xstate'.  We need to ensure
 567  * that our software representation matches what the CPU
 568  * tells us about the state's size.
 569  */
 570 static void check_xstate_against_struct(int nr)
 571 {
 572         /*
 573          * Ask the CPU for the size of the state.
 574          */
 575         int sz = xfeature_size(nr);
 576         /*
 577          * Match each CPU state with the corresponding software
 578          * structure.
 579          */
 580         XCHECK_SZ(sz, nr, XFEATURE_YMM,       struct ymmh_struct);
 581         XCHECK_SZ(sz, nr, XFEATURE_BNDREGS,   struct mpx_bndreg_state);
 582         XCHECK_SZ(sz, nr, XFEATURE_BNDCSR,    struct mpx_bndcsr_state);
 583         XCHECK_SZ(sz, nr, XFEATURE_OPMASK,    struct avx_512_opmask_state);
 584         XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
 585         XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM,  struct avx_512_hi16_state);
 586         XCHECK_SZ(sz, nr, XFEATURE_PKRU,      struct pkru_state);
 587
 588         /*
 589          * Make *SURE* to add any feature numbers in below if
 590          * there are "holes" in the xsave state component
 591          * numbers.
 592          */
 593         if ((nr < XFEATURE_YMM) ||
 594             (nr >= XFEATURE_MAX) ||
 595             (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) {
 596                 WARN_ONCE(1, "no structure for xstate: %d\n", nr);
 597                 XSTATE_WARN_ON(1);
 598         }
 599 }
 600
 601 /*
 602  * This essentially double-checks what the cpu told us about
 603  * how large the XSAVE buffer needs to be.  We are recalculating
 604  * it to be safe.
 605  */
 606 static void do_extra_xstate_size_checks(void)
 607 {
 608         int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 609         int i;
 610
 611         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 612                 if (!xfeature_enabled(i))
 613                         continue;
 614
 615                 check_xstate_against_struct(i);
 616                 /*
 617                  * Supervisor state components can be managed only by
 618                  * XSAVES, which is compacted-format only.
 619                  */
 620                 if (!using_compacted_format())
 621                         XSTATE_WARN_ON(xfeature_is_supervisor(i));
 622
 623                 /* Align from the end of the previous feature */
 624                 if (xfeature_is_aligned(i))
 625                         paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64);
 626                 /*
 627                  * The offset of a given state in the non-compacted
 628                  * format is given to us in a CPUID leaf.  We check
 629                  * them for being ordered (increasing offsets) in
 630                  * setup_xstate_features().
 631                  */
 632                 if (!using_compacted_format())
 633                         paranoid_xstate_size = xfeature_uncompacted_offset(i);
 634                 /*
 635                  * The compacted-format offset always depends on where
 636                  * the previous state ended.
 637                  */
 638                 paranoid_xstate_size += xfeature_size(i);
 639         }
 640         XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
 641 }
 642
 643
 644 /*
 645  * Get total size of enabled xstates in XCR0/xfeatures_mask.
 646  *
 647  * Note the SDM's wording here.  "sub-function 0" only enumerates
 648  * the size of the *user* states.  If we use it to size a buffer
 649  * that we use 'XSAVES' on, we could potentially overflow the
 650  * buffer because 'XSAVES' saves system states too.
 651  *
 652  * Note that we do not currently set any bits on IA32_XSS so
 653  * 'XCR0 | IA32_XSS == XCR0' for now.
 654  */
 655 static unsigned int __init get_xsaves_size(void)
 656 {
 657         unsigned int eax, ebx, ecx, edx;
 658         /*
 659          * - CPUID function 0DH, sub-function 1:
 660          *    EBX enumerates the size (in bytes) required by
 661          *    the XSAVES instruction for an XSAVE area
 662          *    containing all the state components
 663          *    corresponding to bits currently set in
 664          *    XCR0 | IA32_XSS.
 665          */
 666         cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
 667         return ebx;
 668 }
 669
 670 static unsigned int __init get_xsave_size(void)
 671 {
 672         unsigned int eax, ebx, ecx, edx;
 673         /*
 674          * - CPUID function 0DH, sub-function 0:
 675          *    EBX enumerates the size (in bytes) required by
 676          *    the XSAVE instruction for an XSAVE area
 677          *    containing all the *user* state components
 678          *    corresponding to bits currently set in XCR0.
 679          */
 680         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 681         return ebx;
 682 }
 683
 684 /*
 685  * Will the runtime-enumerated 'xstate_size' fit in the init
 686  * task's statically-allocated buffer?
 687  */
 688 static bool is_supported_xstate_size(unsigned int test_xstate_size)
 689 {
 690         if (test_xstate_size <= sizeof(union fpregs_state))
 691                 return true;
 692
 693         pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
 694                         sizeof(union fpregs_state), test_xstate_size);
 695         return false;
 696 }
 697
 698 static int __init init_xstate_size(void)
 699 {
 700         /* Recompute the context size for enabled features: */
 701         unsigned int possible_xstate_size;
 702         unsigned int xsave_size;
 703
 704         xsave_size = get_xsave_size();
 705
 706         if (boot_cpu_has(X86_FEATURE_XSAVES))
 707                 possible_xstate_size = get_xsaves_size();
 708         else
 709                 possible_xstate_size = xsave_size;
 710
 711         /* Ensure we have the space to store all enabled: */
 712         if (!is_supported_xstate_size(possible_xstate_size))
 713                 return -EINVAL;
 714
 715         /*
 716          * The size is OK, we are definitely going to use xsave,
 717          * make it known to the world that we need more space.
 718          */
 719         fpu_kernel_xstate_size = possible_xstate_size;
 720         do_extra_xstate_size_checks();
 721
 722         /*
 723          * User space is always in standard format.
 724          */
 725         fpu_user_xstate_size = xsave_size;
 726         return 0;
 727 }
 728
 729 /*
 730  * We enabled the XSAVE hardware, but something went wrong and
 731  * we can not use it.  Disable it.
 732  */
 733 static void fpu__init_disable_system_xstate(void)
 734 {
 735         xfeatures_mask = 0;
 736         cr4_clear_bits(X86_CR4_OSXSAVE);
 737         setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 738 }
 739
 740 /*
 741  * Enable and initialize the xsave feature.
 742  * Called once per system bootup.
 743  */
 744 void __init fpu__init_system_xstate(void)
 745 {
 746         unsigned int eax, ebx, ecx, edx;
 747         static int on_boot_cpu __initdata = 1;
 748         int err;
 749         int i;
 750
 751         WARN_ON_FPU(!on_boot_cpu);
 752         on_boot_cpu = 0;
 753
 754         if (!boot_cpu_has(X86_FEATURE_FPU)) {
 755                 pr_info("x86/fpu: No FPU detected\n");
 756                 return;
 757         }
 758
 759         if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
 760                 pr_info("x86/fpu: x87 FPU will use %s\n",
 761                         boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
 762                 return;
 763         }
 764
 765         if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
 766                 WARN_ON_FPU(1);
 767                 return;
 768         }
 769
 770         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 771         xfeatures_mask = eax + ((u64)edx << 32);
 772
 773         if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
 774                 /*
 775                  * This indicates that something really unexpected happened
 776                  * with the enumeration.  Disable XSAVE and try to continue
 777                  * booting without it.  This is too early to BUG().
 778                  */
 779                 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask);
 780                 goto out_disable;
 781         }
 782
 783         /*
 784          * Clear XSAVE features that are disabled in the normal CPUID.
 785          */
 786         for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
 787                 if (!boot_cpu_has(xsave_cpuid_features[i]))
 788                         xfeatures_mask &= ~BIT(i);
 789         }
 790
 791         xfeatures_mask &= fpu__get_supported_xfeatures_mask();
 792
 793         /* Enable xstate instructions to be able to continue with initialization: */
 794         fpu__init_cpu_xstate();
 795         err = init_xstate_size();
 796         if (err)
 797                 goto out_disable;
 798
 799         /*
 800          * Update info used for ptrace frames; use standard-format size and no
 801          * supervisor xstates:
 802          */
 803         update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR);
 804
 805         fpu__init_prepare_fx_sw_frame();
 806         setup_init_fpu_buf();
 807         setup_xstate_comp();
 808
 809         /*
 810          * CPU capabilities initialization runs before FPU init. So
 811          * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
 812          * functional, set the feature bit so depending code works.
 813          */
 814         setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
 815
 816         print_xstate_offset_size();
 817
 818         pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
 819                 xfeatures_mask,
 820                 fpu_kernel_xstate_size,
 821                 boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
 822         return;
 823
 824 out_disable:
 825         /* something went wrong, try to boot without any XSAVE support */
 826         fpu__init_disable_system_xstate();
 827 }
 828
 829 /*
 830  * Restore minimal FPU state after suspend:
 831  */
 832 void fpu__resume_cpu(void)
 833 {
 834         /*
 835          * Restore XCR0 on xsave capable CPUs:
 836          */
 837         if (boot_cpu_has(X86_FEATURE_XSAVE))
 838                 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
 839 }
 840
 841 /*
 842  * Given an xstate feature nr, calculate where in the xsave
 843  * buffer the state is.  Callers should ensure that the buffer
 844  * is valid.
 845  */
 846 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 847 {
 848         if (!xfeature_enabled(xfeature_nr)) {
 849                 WARN_ON_FPU(1);
 850                 return NULL;
 851         }
 852
 853         return (void *)xsave + xstate_comp_offsets[xfeature_nr];
 854 }
 855 /*
 856  * Given the xsave area and a state inside, this function returns the
 857  * address of the state.
 858  *
 859  * This is the API that is called to get xstate address in either
 860  * standard format or compacted format of xsave area.
 861  *
 862  * Note that if there is no data for the field in the xsave buffer
 863  * this will return NULL.
 864  *
 865  * Inputs:
 866  *      xstate: the thread's storage area for all FPU data
 867  *      xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 868  *      XFEATURE_SSE, etc...)
 869  * Output:
 870  *      address of the state in the xsave area, or NULL if the
 871  *      field is not present in the xsave buffer.
 872  */
 873 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 874 {
 875         /*
 876          * Do we even *have* xsave state?
 877          */
 878         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 879                 return NULL;
 880
 881         /*
 882          * We should not ever be requesting features that we
 883          * have not enabled.  Remember that pcntxt_mask is
 884          * what we write to the XCR0 register.
 885          */
 886         WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)),
 887                   "get of unsupported state");
 888         /*
 889          * This assumes the last 'xsave*' instruction to
 890          * have requested that 'xfeature_nr' be saved.
 891          * If it did not, we might be seeing and old value
 892          * of the field in the buffer.
 893          *
 894          * This can happen because the last 'xsave' did not
 895          * request that this feature be saved (unlikely)
 896          * or because the "init optimization" caused it
 897          * to not be saved.
 898          */
 899         if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
 900                 return NULL;
 901
 902         return __raw_xsave_addr(xsave, xfeature_nr);
 903 }
 904 EXPORT_SYMBOL_GPL(get_xsave_addr);
 905
 906 /*
 907  * This wraps up the common operations that need to occur when retrieving
 908  * data from xsave state.  It first ensures that the current task was
 909  * using the FPU and retrieves the data in to a buffer.  It then calculates
 910  * the offset of the requested field in the buffer.
 911  *
 912  * This function is safe to call whether the FPU is in use or not.
 913  *
 914  * Note that this only works on the current task.
 915  *
 916  * Inputs:
 917  *      @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 918  *      XFEATURE_SSE, etc...)
 919  * Output:
 920  *      address of the state in the xsave area or NULL if the state
 921  *      is not present or is in its 'init state'.
 922  */
 923 const void *get_xsave_field_ptr(int xfeature_nr)
 924 {
 925         struct fpu *fpu = &current->thread.fpu;
 926
 927         /*
 928          * fpu__save() takes the CPU's xstate registers
 929          * and saves them off to the 'fpu memory buffer.
 930          */
 931         fpu__save(fpu);
 932
 933         return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
 934 }
 935
 936 #ifdef CONFIG_ARCH_HAS_PKEYS
 937
 938 /*
 939  * This will go out and modify PKRU register to set the access
 940  * rights for @pkey to @init_val.
 941  */
 942 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 943                 unsigned long init_val)
 944 {
 945         u32 old_pkru;
 946         int pkey_shift = (pkey * PKRU_BITS_PER_PKEY);
 947         u32 new_pkru_bits = 0;
 948
 949         /*
 950          * This check implies XSAVE support.  OSPKE only gets
 951          * set if we enable XSAVE and we enable PKU in XCR0.
 952          */
 953         if (!boot_cpu_has(X86_FEATURE_OSPKE))
 954                 return -EINVAL;
 955
 956         /*
 957          * This code should only be called with valid 'pkey'
 958          * values originating from in-kernel users.  Complain
 959          * if a bad value is observed.
 960          */
 961         WARN_ON_ONCE(pkey >= arch_max_pkey());
 962
 963         /* Set the bits we need in PKRU:  */
 964         if (init_val & PKEY_DISABLE_ACCESS)
 965                 new_pkru_bits |= PKRU_AD_BIT;
 966         if (init_val & PKEY_DISABLE_WRITE)
 967                 new_pkru_bits |= PKRU_WD_BIT;
 968
 969         /* Shift the bits in to the correct place in PKRU for pkey: */
 970         new_pkru_bits <<= pkey_shift;
 971
 972         /* Get old PKRU and mask off any old bits in place: */
 973         old_pkru = read_pkru();
 974         old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
 975
 976         /* Write old part along with new part: */
 977         write_pkru(old_pkru | new_pkru_bits);
 978
 979         return 0;
 980 }
 981 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
 982
 983 /*
 984  * Weird legacy quirk: SSE and YMM states store information in the
 985  * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
 986  * area is marked as unused in the xfeatures header, we need to copy
 987  * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
 988  */
 989 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
 990 {
 991         if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
 992                 return false;
 993
 994         if (xfeatures & XFEATURE_MASK_FP)
 995                 return false;
 996
 997         return true;
 998 }
 999
1000 static void fill_gap(unsigned to, void **kbuf, unsigned *pos, unsigned *count)
1001 {
1002         if (*pos < to) {
1003                 unsigned size = to - *pos;
1004
1005                 if (size > *count)
1006                         size = *count;
1007                 memcpy(*kbuf, (void *)&init_fpstate.xsave + *pos, size);
1008                 *kbuf += size;
1009                 *pos += size;
1010                 *count -= size;
1011         }
1012 }
1013
1014 static void copy_part(unsigned offset, unsigned size, void *from,
1015                         void **kbuf, unsigned *pos, unsigned *count)
1016 {
1017         fill_gap(offset, kbuf, pos, count);
1018         if (size > *count)
1019                 size = *count;
1020         if (size) {
1021                 memcpy(*kbuf, from, size);
1022                 *kbuf += size;
1023                 *pos += size;
1024                 *count -= size;
1025         }
1026 }
1027
1028 /*
1029  * Convert from kernel XSAVES compacted format to standard format and copy
1030  * to a kernel-space ptrace buffer.
1031  *
1032  * It supports partial copy but pos always starts from zero. This is called
1033  * from xstateregs_get() and there we check the CPU has XSAVES.
1034  */
1035 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
1036 {
1037         struct xstate_header header;
1038         const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
1039         unsigned count = size_total;
1040         int i;
1041
1042         /*
1043          * Currently copy_regset_to_user() starts from pos 0:
1044          */
1045         if (unlikely(offset_start != 0))
1046                 return -EFAULT;
1047
1048         /*
1049          * The destination is a ptrace buffer; we put in only user xstates:
1050          */
1051         memset(&header, 0, sizeof(header));
1052         header.xfeatures = xsave->header.xfeatures;
1053         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
1054
1055         if (header.xfeatures & XFEATURE_MASK_FP)
1056                 copy_part(0, off_mxcsr,
1057                           &xsave->i387, &kbuf, &offset_start, &count);
1058         if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
1059                 copy_part(off_mxcsr, MXCSR_AND_FLAGS_SIZE,
1060                           &xsave->i387.mxcsr, &kbuf, &offset_start, &count);
1061         if (header.xfeatures & XFEATURE_MASK_FP)
1062                 copy_part(offsetof(struct fxregs_state, st_space), 128,
1063                           &xsave->i387.st_space, &kbuf, &offset_start, &count);
1064         if (header.xfeatures & XFEATURE_MASK_SSE)
1065                 copy_part(xstate_offsets[XFEATURE_SSE], 256,
1066                           &xsave->i387.xmm_space, &kbuf, &offset_start, &count);
1067         /*
1068          * Fill xsave->i387.sw_reserved value for ptrace frame:
1069          */
1070         copy_part(offsetof(struct fxregs_state, sw_reserved), 48,
1071                   xstate_fx_sw_bytes, &kbuf, &offset_start, &count);
1072         /*
1073          * Copy xregs_state->header:
1074          */
1075         copy_part(offsetof(struct xregs_state, header), sizeof(header),
1076                   &header, &kbuf, &offset_start, &count);
1077
1078         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
1079                 /*
1080                  * Copy only in-use xstates:
1081                  */
1082                 if ((header.xfeatures >> i) & 1) {
1083                         void *src = __raw_xsave_addr(xsave, i);
1084
1085                         copy_part(xstate_offsets[i], xstate_sizes[i],
1086                                   src, &kbuf, &offset_start, &count);
1087                 }
1088
1089         }
1090         fill_gap(size_total, &kbuf, &offset_start, &count);
1091
1092         return 0;
1093 }
1094
1095 static inline int
1096 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total)
1097 {
1098         if (!size)
1099                 return 0;
1100
1101         if (offset < size_total) {
1102                 unsigned int copy = min(size, size_total - offset);
1103
1104                 if (__copy_to_user(ubuf + offset, data, copy))
1105                         return -EFAULT;
1106         }
1107         return 0;
1108 }
1109
1110 /*
1111  * Convert from kernel XSAVES compacted format to standard format and copy
1112  * to a user-space buffer. It supports partial copy but pos always starts from
1113  * zero. This is called from xstateregs_get() and there we check the CPU
1114  * has XSAVES.
1115  */
1116 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
1117 {
1118         unsigned int offset, size;
1119         int ret, i;
1120         struct xstate_header header;
1121
1122         /*
1123          * Currently copy_regset_to_user() starts from pos 0:
1124          */
1125         if (unlikely(offset_start != 0))
1126                 return -EFAULT;
1127
1128         /*
1129          * The destination is a ptrace buffer; we put in only user xstates:
1130          */
1131         memset(&header, 0, sizeof(header));
1132         header.xfeatures = xsave->header.xfeatures;
1133         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
1134
1135         /*
1136          * Copy xregs_state->header:
1137          */
1138         offset = offsetof(struct xregs_state, header);
1139         size = sizeof(header);
1140
1141         ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total);
1142         if (ret)
1143                 return ret;
1144
1145         for (i = 0; i < XFEATURE_MAX; i++) {
1146                 /*
1147                  * Copy only in-use xstates:
1148                  */
1149                 if ((header.xfeatures >> i) & 1) {
1150                         void *src = __raw_xsave_addr(xsave, i);
1151
1152                         offset = xstate_offsets[i];
1153                         size = xstate_sizes[i];
1154
1155                         /* The next component has to fit fully into the output buffer: */
1156                         if (offset + size > size_total)
1157                                 break;
1158
1159                         ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
1160                         if (ret)
1161                                 return ret;
1162                 }
1163
1164         }
1165
1166         if (xfeatures_mxcsr_quirk(header.xfeatures)) {
1167                 offset = offsetof(struct fxregs_state, mxcsr);
1168                 size = MXCSR_AND_FLAGS_SIZE;
1169                 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total);
1170         }
1171
1172         /*
1173          * Fill xsave->i387.sw_reserved value for ptrace frame:
1174          */
1175         offset = offsetof(struct fxregs_state, sw_reserved);
1176         size = sizeof(xstate_fx_sw_bytes);
1177
1178         ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total);
1179         if (ret)
1180                 return ret;
1181
1182         return 0;
1183 }
1184
1185 /*
1186  * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
1187  * and copy to the target thread. This is called from xstateregs_set().
1188  */
1189 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
1190 {
1191         unsigned int offset, size;
1192         int i;
1193         struct xstate_header hdr;
1194
1195         offset = offsetof(struct xregs_state, header);
1196         size = sizeof(hdr);
1197
1198         memcpy(&hdr, kbuf + offset, size);
1199
1200         if (validate_xstate_header(&hdr))
1201                 return -EINVAL;
1202
1203         for (i = 0; i < XFEATURE_MAX; i++) {
1204                 u64 mask = ((u64)1 << i);
1205
1206                 if (hdr.xfeatures & mask) {
1207                         void *dst = __raw_xsave_addr(xsave, i);
1208
1209                         offset = xstate_offsets[i];
1210                         size = xstate_sizes[i];
1211
1212                         memcpy(dst, kbuf + offset, size);
1213                 }
1214         }
1215
1216         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1217                 offset = offsetof(struct fxregs_state, mxcsr);
1218                 size = MXCSR_AND_FLAGS_SIZE;
1219                 memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
1220         }
1221
1222         /*
1223          * The state that came in from userspace was user-state only.
1224          * Mask all the user states out of 'xfeatures':
1225          */
1226         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1227
1228         /*
1229          * Add back in the features that came in from userspace:
1230          */
1231         xsave->header.xfeatures |= hdr.xfeatures;
1232
1233         return 0;
1234 }
1235
1236 /*
1237  * Convert from a ptrace or sigreturn standard-format user-space buffer to
1238  * kernel XSAVES format and copy to the target thread. This is called from
1239  * xstateregs_set(), as well as potentially from the sigreturn() and
1240  * rt_sigreturn() system calls.
1241  */
1242 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
1243 {
1244         unsigned int offset, size;
1245         int i;
1246         struct xstate_header hdr;
1247
1248         offset = offsetof(struct xregs_state, header);
1249         size = sizeof(hdr);
1250
1251         if (__copy_from_user(&hdr, ubuf + offset, size))
1252                 return -EFAULT;
1253
1254         if (validate_xstate_header(&hdr))
1255                 return -EINVAL;
1256
1257         for (i = 0; i < XFEATURE_MAX; i++) {
1258                 u64 mask = ((u64)1 << i);
1259
1260                 if (hdr.xfeatures & mask) {
1261                         void *dst = __raw_xsave_addr(xsave, i);
1262
1263                         offset = xstate_offsets[i];
1264                         size = xstate_sizes[i];
1265
1266                         if (__copy_from_user(dst, ubuf + offset, size))
1267                                 return -EFAULT;
1268                 }
1269         }
1270
1271         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1272                 offset = offsetof(struct fxregs_state, mxcsr);
1273                 size = MXCSR_AND_FLAGS_SIZE;
1274                 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
1275                         return -EFAULT;
1276         }
1277
1278         /*
1279          * The state that came in from userspace was user-state only.
1280          * Mask all the user states out of 'xfeatures':
1281          */
1282         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1283
1284         /*
1285          * Add back in the features that came in from userspace:
1286          */
1287         xsave->header.xfeatures |= hdr.xfeatures;
1288
1289         return 0;
1290 }
1291
1292 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1293 /*
1294  * Report the amount of time elapsed in millisecond since last AVX512
1295  * use in the task.
1296  */
1297 static void avx512_status(struct seq_file *m, struct task_struct *task)
1298 {
1299         unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1300         long delta;
1301
1302         if (!timestamp) {
1303                 /*
1304                  * Report -1 if no AVX512 usage
1305                  */
1306                 delta = -1;
1307         } else {
1308                 delta = (long)(jiffies - timestamp);
1309                 /*
1310                  * Cap to LONG_MAX if time difference > LONG_MAX
1311                  */
1312                 if (delta < 0)
1313                         delta = LONG_MAX;
1314                 delta = jiffies_to_msecs(delta);
1315         }
1316
1317         seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1318         seq_putc(m, '\n');
1319 }
1320
1321 /*
1322  * Report architecture specific information
1323  */
1324 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1325                         struct pid *pid, struct task_struct *task)
1326 {
1327         /*
1328          * Report AVX512 state if the processor and build option supported.
1329          */
1330         if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1331                 avx512_status(m, task);
1332
1333         return 0;
1334 }
1335 #endif /* CONFIG_PROC_PID_ARCH_STATUS */