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         "PASID state",
  41         "unknown xstate feature"        ,
  42 };
  43
  44 static short xsave_cpuid_features[] __initdata = {
  45         X86_FEATURE_FPU,
  46         X86_FEATURE_XMM,
  47         X86_FEATURE_AVX,
  48         X86_FEATURE_MPX,
  49         X86_FEATURE_MPX,
  50         X86_FEATURE_AVX512F,
  51         X86_FEATURE_AVX512F,
  52         X86_FEATURE_AVX512F,
  53         X86_FEATURE_INTEL_PT,
  54         X86_FEATURE_PKU,
  55         X86_FEATURE_ENQCMD,
  56 };
  57
  58 /*
  59  * This represents the full set of bits that should ever be set in a kernel
  60  * XSAVE buffer, both supervisor and user xstates.
  61  */
  62 u64 xfeatures_mask_all __read_mostly;
  63
  64 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  65 static unsigned int xstate_sizes[XFEATURE_MAX]   = { [ 0 ... XFEATURE_MAX - 1] = -1};
  66 static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  67 static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  68
  69 /*
  70  * The XSAVE area of kernel can be in standard or compacted format;
  71  * it is always in standard format for user mode. This is the user
  72  * mode standard format size used for signal and ptrace frames.
  73  */
  74 unsigned int fpu_user_xstate_size;
  75
  76 /*
  77  * Return whether the system supports a given xfeature.
  78  *
  79  * Also return the name of the (most advanced) feature that the caller requested:
  80  */
  81 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
  82 {
  83         u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask_all;
  84
  85         if (unlikely(feature_name)) {
  86                 long xfeature_idx, max_idx;
  87                 u64 xfeatures_print;
  88                 /*
  89                  * So we use FLS here to be able to print the most advanced
  90                  * feature that was requested but is missing. So if a driver
  91                  * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
  92                  * missing AVX feature - this is the most informative message
  93                  * to users:
  94                  */
  95                 if (xfeatures_missing)
  96                         xfeatures_print = xfeatures_missing;
  97                 else
  98                         xfeatures_print = xfeatures_needed;
  99
 100                 xfeature_idx = fls64(xfeatures_print)-1;
 101                 max_idx = ARRAY_SIZE(xfeature_names)-1;
 102                 xfeature_idx = min(xfeature_idx, max_idx);
 103
 104                 *feature_name = xfeature_names[xfeature_idx];
 105         }
 106
 107         if (xfeatures_missing)
 108                 return 0;
 109
 110         return 1;
 111 }
 112 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
 113
 114 static bool xfeature_is_supervisor(int xfeature_nr)
 115 {
 116         /*
 117          * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1)
 118          * returns ECX[0] set to (1) for a supervisor state, and cleared (0)
 119          * for a user state.
 120          */
 121         u32 eax, ebx, ecx, edx;
 122
 123         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 124         return ecx & 1;
 125 }
 126
 127 /*
 128  * When executing XSAVEOPT (or other optimized XSAVE instructions), if
 129  * a processor implementation detects that an FPU state component is still
 130  * (or is again) in its initialized state, it may clear the corresponding
 131  * bit in the header.xfeatures field, and can skip the writeout of registers
 132  * to the corresponding memory layout.
 133  *
 134  * This means that when the bit is zero, the state component might still contain
 135  * some previous - non-initialized register state.
 136  *
 137  * Before writing xstate information to user-space we sanitize those components,
 138  * to always ensure that the memory layout of a feature will be in the init state
 139  * if the corresponding header bit is zero. This is to ensure that user-space doesn't
 140  * see some stale state in the memory layout during signal handling, debugging etc.
 141  */
 142 void fpstate_sanitize_xstate(struct fpu *fpu)
 143 {
 144         struct fxregs_state *fx = &fpu->state.fxsave;
 145         int feature_bit;
 146         u64 xfeatures;
 147
 148         if (!use_xsaveopt())
 149                 return;
 150
 151         xfeatures = fpu->state.xsave.header.xfeatures;
 152
 153         /*
 154          * None of the feature bits are in init state. So nothing else
 155          * to do for us, as the memory layout is up to date.
 156          */
 157         if ((xfeatures & xfeatures_mask_all) == xfeatures_mask_all)
 158                 return;
 159
 160         /*
 161          * FP is in init state
 162          */
 163         if (!(xfeatures & XFEATURE_MASK_FP)) {
 164                 fx->cwd = 0x37f;
 165                 fx->swd = 0;
 166                 fx->twd = 0;
 167                 fx->fop = 0;
 168                 fx->rip = 0;
 169                 fx->rdp = 0;
 170                 memset(fx->st_space, 0, sizeof(fx->st_space));
 171         }
 172
 173         /*
 174          * SSE is in init state
 175          */
 176         if (!(xfeatures & XFEATURE_MASK_SSE))
 177                 memset(fx->xmm_space, 0, sizeof(fx->xmm_space));
 178
 179         /*
 180          * First two features are FPU and SSE, which above we handled
 181          * in a special way already:
 182          */
 183         feature_bit = 0x2;
 184         xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
 185
 186         /*
 187          * Update all the remaining memory layouts according to their
 188          * standard xstate layout, if their header bit is in the init
 189          * state:
 190          */
 191         while (xfeatures) {
 192                 if (xfeatures & 0x1) {
 193                         int offset = xstate_comp_offsets[feature_bit];
 194                         int size = xstate_sizes[feature_bit];
 195
 196                         memcpy((void *)fx + offset,
 197                                (void *)&init_fpstate.xsave + offset,
 198                                size);
 199                 }
 200
 201                 xfeatures >>= 1;
 202                 feature_bit++;
 203         }
 204 }
 205
 206 /*
 207  * Enable the extended processor state save/restore feature.
 208  * Called once per CPU onlining.
 209  */
 210 void fpu__init_cpu_xstate(void)
 211 {
 212         u64 unsup_bits;
 213
 214         if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask_all)
 215                 return;
 216         /*
 217          * Unsupported supervisor xstates should not be found in
 218          * the xfeatures mask.
 219          */
 220         unsup_bits = xfeatures_mask_all & XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
 221         WARN_ONCE(unsup_bits, "x86/fpu: Found unsupported supervisor xstates: 0x%llx\n",
 222                   unsup_bits);
 223
 224         xfeatures_mask_all &= ~XFEATURE_MASK_SUPERVISOR_UNSUPPORTED;
 225
 226         cr4_set_bits(X86_CR4_OSXSAVE);
 227
 228         /*
 229          * XCR_XFEATURE_ENABLED_MASK (aka. XCR0) sets user features
 230          * managed by XSAVE{C, OPT, S} and XRSTOR{S}.  Only XSAVE user
 231          * states can be set here.
 232          */
 233         xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
 234
 235         /*
 236          * MSR_IA32_XSS sets supervisor states managed by XSAVES.
 237          */
 238         if (boot_cpu_has(X86_FEATURE_XSAVES)) {
 239                 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
 240                                      xfeatures_mask_dynamic());
 241         }
 242 }
 243
 244 static bool xfeature_enabled(enum xfeature xfeature)
 245 {
 246         return xfeatures_mask_all & BIT_ULL(xfeature);
 247 }
 248
 249 /*
 250  * Record the offsets and sizes of various xstates contained
 251  * in the XSAVE state memory layout.
 252  */
 253 static void __init setup_xstate_features(void)
 254 {
 255         u32 eax, ebx, ecx, edx, i;
 256         /* start at the beginning of the "extended state" */
 257         unsigned int last_good_offset = offsetof(struct xregs_state,
 258                                                  extended_state_area);
 259         /*
 260          * The FP xstates and SSE xstates are legacy states. They are always
 261          * in the fixed offsets in the xsave area in either compacted form
 262          * or standard form.
 263          */
 264         xstate_offsets[XFEATURE_FP]     = 0;
 265         xstate_sizes[XFEATURE_FP]       = offsetof(struct fxregs_state,
 266                                                    xmm_space);
 267
 268         xstate_offsets[XFEATURE_SSE]    = xstate_sizes[XFEATURE_FP];
 269         xstate_sizes[XFEATURE_SSE]      = sizeof_field(struct fxregs_state,
 270                                                        xmm_space);
 271
 272         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 273                 if (!xfeature_enabled(i))
 274                         continue;
 275
 276                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 277
 278                 xstate_sizes[i] = eax;
 279
 280                 /*
 281                  * If an xfeature is supervisor state, the offset in EBX is
 282                  * invalid, leave it to -1.
 283                  */
 284                 if (xfeature_is_supervisor(i))
 285                         continue;
 286
 287                 xstate_offsets[i] = ebx;
 288
 289                 /*
 290                  * In our xstate size checks, we assume that the highest-numbered
 291                  * xstate feature has the highest offset in the buffer.  Ensure
 292                  * it does.
 293                  */
 294                 WARN_ONCE(last_good_offset > xstate_offsets[i],
 295                           "x86/fpu: misordered xstate at %d\n", last_good_offset);
 296
 297                 last_good_offset = xstate_offsets[i];
 298         }
 299 }
 300
 301 static void __init print_xstate_feature(u64 xstate_mask)
 302 {
 303         const char *feature_name;
 304
 305         if (cpu_has_xfeatures(xstate_mask, &feature_name))
 306                 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
 307 }
 308
 309 /*
 310  * Print out all the supported xstate features:
 311  */
 312 static void __init print_xstate_features(void)
 313 {
 314         print_xstate_feature(XFEATURE_MASK_FP);
 315         print_xstate_feature(XFEATURE_MASK_SSE);
 316         print_xstate_feature(XFEATURE_MASK_YMM);
 317         print_xstate_feature(XFEATURE_MASK_BNDREGS);
 318         print_xstate_feature(XFEATURE_MASK_BNDCSR);
 319         print_xstate_feature(XFEATURE_MASK_OPMASK);
 320         print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
 321         print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
 322         print_xstate_feature(XFEATURE_MASK_PKRU);
 323         print_xstate_feature(XFEATURE_MASK_PASID);
 324 }
 325
 326 /*
 327  * This check is important because it is easy to get XSTATE_*
 328  * confused with XSTATE_BIT_*.
 329  */
 330 #define CHECK_XFEATURE(nr) do {         \
 331         WARN_ON(nr < FIRST_EXTENDED_XFEATURE);  \
 332         WARN_ON(nr >= XFEATURE_MAX);    \
 333 } while (0)
 334
 335 /*
 336  * We could cache this like xstate_size[], but we only use
 337  * it here, so it would be a waste of space.
 338  */
 339 static int xfeature_is_aligned(int xfeature_nr)
 340 {
 341         u32 eax, ebx, ecx, edx;
 342
 343         CHECK_XFEATURE(xfeature_nr);
 344
 345         if (!xfeature_enabled(xfeature_nr)) {
 346                 WARN_ONCE(1, "Checking alignment of disabled xfeature %d\n",
 347                           xfeature_nr);
 348                 return 0;
 349         }
 350
 351         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 352         /*
 353          * The value returned by ECX[1] indicates the alignment
 354          * of state component 'i' when the compacted format
 355          * of the extended region of an XSAVE area is used:
 356          */
 357         return !!(ecx & 2);
 358 }
 359
 360 /*
 361  * This function sets up offsets and sizes of all extended states in
 362  * xsave area. This supports both standard format and compacted format
 363  * of the xsave area.
 364  */
 365 static void __init setup_xstate_comp_offsets(void)
 366 {
 367         unsigned int next_offset;
 368         int i;
 369
 370         /*
 371          * The FP xstates and SSE xstates are legacy states. They are always
 372          * in the fixed offsets in the xsave area in either compacted form
 373          * or standard form.
 374          */
 375         xstate_comp_offsets[XFEATURE_FP] = 0;
 376         xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
 377                                                      xmm_space);
 378
 379         if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
 380                 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 381                         if (xfeature_enabled(i))
 382                                 xstate_comp_offsets[i] = xstate_offsets[i];
 383                 }
 384                 return;
 385         }
 386
 387         next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 388
 389         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 390                 if (!xfeature_enabled(i))
 391                         continue;
 392
 393                 if (xfeature_is_aligned(i))
 394                         next_offset = ALIGN(next_offset, 64);
 395
 396                 xstate_comp_offsets[i] = next_offset;
 397                 next_offset += xstate_sizes[i];
 398         }
 399 }
 400
 401 /*
 402  * Setup offsets of a supervisor-state-only XSAVES buffer:
 403  *
 404  * The offsets stored in xstate_comp_offsets[] only work for one specific
 405  * value of the Requested Feature BitMap (RFBM).  In cases where a different
 406  * RFBM value is used, a different set of offsets is required.  This set of
 407  * offsets is for when RFBM=xfeatures_mask_supervisor().
 408  */
 409 static void __init setup_supervisor_only_offsets(void)
 410 {
 411         unsigned int next_offset;
 412         int i;
 413
 414         next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 415
 416         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 417                 if (!xfeature_enabled(i) || !xfeature_is_supervisor(i))
 418                         continue;
 419
 420                 if (xfeature_is_aligned(i))
 421                         next_offset = ALIGN(next_offset, 64);
 422
 423                 xstate_supervisor_only_offsets[i] = next_offset;
 424                 next_offset += xstate_sizes[i];
 425         }
 426 }
 427
 428 /*
 429  * Print out xstate component offsets and sizes
 430  */
 431 static void __init print_xstate_offset_size(void)
 432 {
 433         int i;
 434
 435         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 436                 if (!xfeature_enabled(i))
 437                         continue;
 438                 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
 439                          i, xstate_comp_offsets[i], i, xstate_sizes[i]);
 440         }
 441 }
 442
 443 /*
 444  * setup the xstate image representing the init state
 445  */
 446 static void __init setup_init_fpu_buf(void)
 447 {
 448         static int on_boot_cpu __initdata = 1;
 449
 450         WARN_ON_FPU(!on_boot_cpu);
 451         on_boot_cpu = 0;
 452
 453         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 454                 return;
 455
 456         setup_xstate_features();
 457         print_xstate_features();
 458
 459         if (boot_cpu_has(X86_FEATURE_XSAVES))
 460                 init_fpstate.xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
 461                                                      xfeatures_mask_all;
 462
 463         /*
 464          * Init all the features state with header.xfeatures being 0x0
 465          */
 466         copy_kernel_to_xregs_booting(&init_fpstate.xsave);
 467
 468         /*
 469          * Dump the init state again. This is to identify the init state
 470          * of any feature which is not represented by all zero's.
 471          */
 472         copy_xregs_to_kernel_booting(&init_fpstate.xsave);
 473 }
 474
 475 static int xfeature_uncompacted_offset(int xfeature_nr)
 476 {
 477         u32 eax, ebx, ecx, edx;
 478
 479         /*
 480          * Only XSAVES supports supervisor states and it uses compacted
 481          * format. Checking a supervisor state's uncompacted offset is
 482          * an error.
 483          */
 484         if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {
 485                 WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
 486                 return -1;
 487         }
 488
 489         CHECK_XFEATURE(xfeature_nr);
 490         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 491         return ebx;
 492 }
 493
 494 int xfeature_size(int xfeature_nr)
 495 {
 496         u32 eax, ebx, ecx, edx;
 497
 498         CHECK_XFEATURE(xfeature_nr);
 499         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 500         return eax;
 501 }
 502
 503 /*
 504  * 'XSAVES' implies two different things:
 505  * 1. saving of supervisor/system state
 506  * 2. using the compacted format
 507  *
 508  * Use this function when dealing with the compacted format so
 509  * that it is obvious which aspect of 'XSAVES' is being handled
 510  * by the calling code.
 511  */
 512 int using_compacted_format(void)
 513 {
 514         return boot_cpu_has(X86_FEATURE_XSAVES);
 515 }
 516
 517 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
 518 int validate_user_xstate_header(const struct xstate_header *hdr)
 519 {
 520         /* No unknown or supervisor features may be set */
 521         if (hdr->xfeatures & ~xfeatures_mask_user())
 522                 return -EINVAL;
 523
 524         /* Userspace must use the uncompacted format */
 525         if (hdr->xcomp_bv)
 526                 return -EINVAL;
 527
 528         /*
 529          * If 'reserved' is shrunken to add a new field, make sure to validate
 530          * that new field here!
 531          */
 532         BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
 533
 534         /* No reserved bits may be set */
 535         if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
 536                 return -EINVAL;
 537
 538         return 0;
 539 }
 540
 541 static void __xstate_dump_leaves(void)
 542 {
 543         int i;
 544         u32 eax, ebx, ecx, edx;
 545         static int should_dump = 1;
 546
 547         if (!should_dump)
 548                 return;
 549         should_dump = 0;
 550         /*
 551          * Dump out a few leaves past the ones that we support
 552          * just in case there are some goodies up there
 553          */
 554         for (i = 0; i < XFEATURE_MAX + 10; i++) {
 555                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 556                 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
 557                         XSTATE_CPUID, i, eax, ebx, ecx, edx);
 558         }
 559 }
 560
 561 #define XSTATE_WARN_ON(x) do {                                                  \
 562         if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) {        \
 563                 __xstate_dump_leaves();                                         \
 564         }                                                                       \
 565 } while (0)
 566
 567 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do {                      \
 568         if ((nr == nr_macro) &&                                         \
 569             WARN_ONCE(sz != sizeof(__struct),                           \
 570                 "%s: struct is %zu bytes, cpu state %d bytes\n",        \
 571                 __stringify(nr_macro), sizeof(__struct), sz)) {         \
 572                 __xstate_dump_leaves();                                 \
 573         }                                                               \
 574 } while (0)
 575
 576 /*
 577  * We have a C struct for each 'xstate'.  We need to ensure
 578  * that our software representation matches what the CPU
 579  * tells us about the state's size.
 580  */
 581 static void check_xstate_against_struct(int nr)
 582 {
 583         /*
 584          * Ask the CPU for the size of the state.
 585          */
 586         int sz = xfeature_size(nr);
 587         /*
 588          * Match each CPU state with the corresponding software
 589          * structure.
 590          */
 591         XCHECK_SZ(sz, nr, XFEATURE_YMM,       struct ymmh_struct);
 592         XCHECK_SZ(sz, nr, XFEATURE_BNDREGS,   struct mpx_bndreg_state);
 593         XCHECK_SZ(sz, nr, XFEATURE_BNDCSR,    struct mpx_bndcsr_state);
 594         XCHECK_SZ(sz, nr, XFEATURE_OPMASK,    struct avx_512_opmask_state);
 595         XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
 596         XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM,  struct avx_512_hi16_state);
 597         XCHECK_SZ(sz, nr, XFEATURE_PKRU,      struct pkru_state);
 598         XCHECK_SZ(sz, nr, XFEATURE_PASID,     struct ia32_pasid_state);
 599
 600         /*
 601          * Make *SURE* to add any feature numbers in below if
 602          * there are "holes" in the xsave state component
 603          * numbers.
 604          */
 605         if ((nr < XFEATURE_YMM) ||
 606             (nr >= XFEATURE_MAX) ||
 607             (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||
 608             ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_LBR))) {
 609                 WARN_ONCE(1, "no structure for xstate: %d\n", nr);
 610                 XSTATE_WARN_ON(1);
 611         }
 612 }
 613
 614 /*
 615  * This essentially double-checks what the cpu told us about
 616  * how large the XSAVE buffer needs to be.  We are recalculating
 617  * it to be safe.
 618  *
 619  * Dynamic XSAVE features allocate their own buffers and are not
 620  * covered by these checks. Only the size of the buffer for task->fpu
 621  * is checked here.
 622  */
 623 static void do_extra_xstate_size_checks(void)
 624 {
 625         int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 626         int i;
 627
 628         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 629                 if (!xfeature_enabled(i))
 630                         continue;
 631
 632                 check_xstate_against_struct(i);
 633                 /*
 634                  * Supervisor state components can be managed only by
 635                  * XSAVES, which is compacted-format only.
 636                  */
 637                 if (!using_compacted_format())
 638                         XSTATE_WARN_ON(xfeature_is_supervisor(i));
 639
 640                 /* Align from the end of the previous feature */
 641                 if (xfeature_is_aligned(i))
 642                         paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64);
 643                 /*
 644                  * The offset of a given state in the non-compacted
 645                  * format is given to us in a CPUID leaf.  We check
 646                  * them for being ordered (increasing offsets) in
 647                  * setup_xstate_features().
 648                  */
 649                 if (!using_compacted_format())
 650                         paranoid_xstate_size = xfeature_uncompacted_offset(i);
 651                 /*
 652                  * The compacted-format offset always depends on where
 653                  * the previous state ended.
 654                  */
 655                 paranoid_xstate_size += xfeature_size(i);
 656         }
 657         XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
 658 }
 659
 660
 661 /*
 662  * Get total size of enabled xstates in XCR0 | IA32_XSS.
 663  *
 664  * Note the SDM's wording here.  "sub-function 0" only enumerates
 665  * the size of the *user* states.  If we use it to size a buffer
 666  * that we use 'XSAVES' on, we could potentially overflow the
 667  * buffer because 'XSAVES' saves system states too.
 668  */
 669 static unsigned int __init get_xsaves_size(void)
 670 {
 671         unsigned int eax, ebx, ecx, edx;
 672         /*
 673          * - CPUID function 0DH, sub-function 1:
 674          *    EBX enumerates the size (in bytes) required by
 675          *    the XSAVES instruction for an XSAVE area
 676          *    containing all the state components
 677          *    corresponding to bits currently set in
 678          *    XCR0 | IA32_XSS.
 679          */
 680         cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
 681         return ebx;
 682 }
 683
 684 /*
 685  * Get the total size of the enabled xstates without the dynamic supervisor
 686  * features.
 687  */
 688 static unsigned int __init get_xsaves_size_no_dynamic(void)
 689 {
 690         u64 mask = xfeatures_mask_dynamic();
 691         unsigned int size;
 692
 693         if (!mask)
 694                 return get_xsaves_size();
 695
 696         /* Disable dynamic features. */
 697         wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor());
 698
 699         /*
 700          * Ask the hardware what size is required of the buffer.
 701          * This is the size required for the task->fpu buffer.
 702          */
 703         size = get_xsaves_size();
 704
 705         /* Re-enable dynamic features so XSAVES will work on them again. */
 706         wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | mask);
 707
 708         return size;
 709 }
 710
 711 static unsigned int __init get_xsave_size(void)
 712 {
 713         unsigned int eax, ebx, ecx, edx;
 714         /*
 715          * - CPUID function 0DH, sub-function 0:
 716          *    EBX enumerates the size (in bytes) required by
 717          *    the XSAVE instruction for an XSAVE area
 718          *    containing all the *user* state components
 719          *    corresponding to bits currently set in XCR0.
 720          */
 721         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 722         return ebx;
 723 }
 724
 725 /*
 726  * Will the runtime-enumerated 'xstate_size' fit in the init
 727  * task's statically-allocated buffer?
 728  */
 729 static bool is_supported_xstate_size(unsigned int test_xstate_size)
 730 {
 731         if (test_xstate_size <= sizeof(union fpregs_state))
 732                 return true;
 733
 734         pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
 735                         sizeof(union fpregs_state), test_xstate_size);
 736         return false;
 737 }
 738
 739 static int __init init_xstate_size(void)
 740 {
 741         /* Recompute the context size for enabled features: */
 742         unsigned int possible_xstate_size;
 743         unsigned int xsave_size;
 744
 745         xsave_size = get_xsave_size();
 746
 747         if (boot_cpu_has(X86_FEATURE_XSAVES))
 748                 possible_xstate_size = get_xsaves_size_no_dynamic();
 749         else
 750                 possible_xstate_size = xsave_size;
 751
 752         /* Ensure we have the space to store all enabled: */
 753         if (!is_supported_xstate_size(possible_xstate_size))
 754                 return -EINVAL;
 755
 756         /*
 757          * The size is OK, we are definitely going to use xsave,
 758          * make it known to the world that we need more space.
 759          */
 760         fpu_kernel_xstate_size = possible_xstate_size;
 761         do_extra_xstate_size_checks();
 762
 763         /*
 764          * User space is always in standard format.
 765          */
 766         fpu_user_xstate_size = xsave_size;
 767         return 0;
 768 }
 769
 770 /*
 771  * We enabled the XSAVE hardware, but something went wrong and
 772  * we can not use it.  Disable it.
 773  */
 774 static void fpu__init_disable_system_xstate(void)
 775 {
 776         xfeatures_mask_all = 0;
 777         cr4_clear_bits(X86_CR4_OSXSAVE);
 778         setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 779 }
 780
 781 /*
 782  * Enable and initialize the xsave feature.
 783  * Called once per system bootup.
 784  */
 785 void __init fpu__init_system_xstate(void)
 786 {
 787         unsigned int eax, ebx, ecx, edx;
 788         static int on_boot_cpu __initdata = 1;
 789         int err;
 790         int i;
 791
 792         WARN_ON_FPU(!on_boot_cpu);
 793         on_boot_cpu = 0;
 794
 795         if (!boot_cpu_has(X86_FEATURE_FPU)) {
 796                 pr_info("x86/fpu: No FPU detected\n");
 797                 return;
 798         }
 799
 800         if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
 801                 pr_info("x86/fpu: x87 FPU will use %s\n",
 802                         boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
 803                 return;
 804         }
 805
 806         if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
 807                 WARN_ON_FPU(1);
 808                 return;
 809         }
 810
 811         /*
 812          * Find user xstates supported by the processor.
 813          */
 814         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 815         xfeatures_mask_all = eax + ((u64)edx << 32);
 816
 817         /*
 818          * Find supervisor xstates supported by the processor.
 819          */
 820         cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
 821         xfeatures_mask_all |= ecx + ((u64)edx << 32);
 822
 823         if ((xfeatures_mask_user() & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
 824                 /*
 825                  * This indicates that something really unexpected happened
 826                  * with the enumeration.  Disable XSAVE and try to continue
 827                  * booting without it.  This is too early to BUG().
 828                  */
 829                 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n",
 830                        xfeatures_mask_all);
 831                 goto out_disable;
 832         }
 833
 834         /*
 835          * Clear XSAVE features that are disabled in the normal CPUID.
 836          */
 837         for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
 838                 if (!boot_cpu_has(xsave_cpuid_features[i]))
 839                         xfeatures_mask_all &= ~BIT_ULL(i);
 840         }
 841
 842         xfeatures_mask_all &= fpu__get_supported_xfeatures_mask();
 843
 844         /* Enable xstate instructions to be able to continue with initialization: */
 845         fpu__init_cpu_xstate();
 846         err = init_xstate_size();
 847         if (err)
 848                 goto out_disable;
 849
 850         /*
 851          * Update info used for ptrace frames; use standard-format size and no
 852          * supervisor xstates:
 853          */
 854         update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask_user());
 855
 856         fpu__init_prepare_fx_sw_frame();
 857         setup_init_fpu_buf();
 858         setup_xstate_comp_offsets();
 859         setup_supervisor_only_offsets();
 860         print_xstate_offset_size();
 861
 862         pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
 863                 xfeatures_mask_all,
 864                 fpu_kernel_xstate_size,
 865                 boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
 866         return;
 867
 868 out_disable:
 869         /* something went wrong, try to boot without any XSAVE support */
 870         fpu__init_disable_system_xstate();
 871 }
 872
 873 /*
 874  * Restore minimal FPU state after suspend:
 875  */
 876 void fpu__resume_cpu(void)
 877 {
 878         /*
 879          * Restore XCR0 on xsave capable CPUs:
 880          */
 881         if (boot_cpu_has(X86_FEATURE_XSAVE))
 882                 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask_user());
 883
 884         /*
 885          * Restore IA32_XSS. The same CPUID bit enumerates support
 886          * of XSAVES and MSR_IA32_XSS.
 887          */
 888         if (boot_cpu_has(X86_FEATURE_XSAVES)) {
 889                 wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()  |
 890                                      xfeatures_mask_dynamic());
 891         }
 892 }
 893
 894 /*
 895  * Given an xstate feature nr, calculate where in the xsave
 896  * buffer the state is.  Callers should ensure that the buffer
 897  * is valid.
 898  */
 899 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 900 {
 901         if (!xfeature_enabled(xfeature_nr)) {
 902                 WARN_ON_FPU(1);
 903                 return NULL;
 904         }
 905
 906         return (void *)xsave + xstate_comp_offsets[xfeature_nr];
 907 }
 908 /*
 909  * Given the xsave area and a state inside, this function returns the
 910  * address of the state.
 911  *
 912  * This is the API that is called to get xstate address in either
 913  * standard format or compacted format of xsave area.
 914  *
 915  * Note that if there is no data for the field in the xsave buffer
 916  * this will return NULL.
 917  *
 918  * Inputs:
 919  *      xstate: the thread's storage area for all FPU data
 920  *      xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 921  *      XFEATURE_SSE, etc...)
 922  * Output:
 923  *      address of the state in the xsave area, or NULL if the
 924  *      field is not present in the xsave buffer.
 925  */
 926 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 927 {
 928         /*
 929          * Do we even *have* xsave state?
 930          */
 931         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 932                 return NULL;
 933
 934         /*
 935          * We should not ever be requesting features that we
 936          * have not enabled.
 937          */
 938         WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
 939                   "get of unsupported state");
 940         /*
 941          * This assumes the last 'xsave*' instruction to
 942          * have requested that 'xfeature_nr' be saved.
 943          * If it did not, we might be seeing and old value
 944          * of the field in the buffer.
 945          *
 946          * This can happen because the last 'xsave' did not
 947          * request that this feature be saved (unlikely)
 948          * or because the "init optimization" caused it
 949          * to not be saved.
 950          */
 951         if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
 952                 return NULL;
 953
 954         return __raw_xsave_addr(xsave, xfeature_nr);
 955 }
 956 EXPORT_SYMBOL_GPL(get_xsave_addr);
 957
 958 /*
 959  * This wraps up the common operations that need to occur when retrieving
 960  * data from xsave state.  It first ensures that the current task was
 961  * using the FPU and retrieves the data in to a buffer.  It then calculates
 962  * the offset of the requested field in the buffer.
 963  *
 964  * This function is safe to call whether the FPU is in use or not.
 965  *
 966  * Note that this only works on the current task.
 967  *
 968  * Inputs:
 969  *      @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 970  *      XFEATURE_SSE, etc...)
 971  * Output:
 972  *      address of the state in the xsave area or NULL if the state
 973  *      is not present or is in its 'init state'.
 974  */
 975 const void *get_xsave_field_ptr(int xfeature_nr)
 976 {
 977         struct fpu *fpu = &current->thread.fpu;
 978
 979         /*
 980          * fpu__save() takes the CPU's xstate registers
 981          * and saves them off to the 'fpu memory buffer.
 982          */
 983         fpu__save(fpu);
 984
 985         return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
 986 }
 987
 988 #ifdef CONFIG_ARCH_HAS_PKEYS
 989
 990 /*
 991  * This will go out and modify PKRU register to set the access
 992  * rights for @pkey to @init_val.
 993  */
 994 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 995                 unsigned long init_val)
 996 {
 997         u32 old_pkru;
 998         int pkey_shift = (pkey * PKRU_BITS_PER_PKEY);
 999         u32 new_pkru_bits = 0;
1000
1001         /*
1002          * This check implies XSAVE support.  OSPKE only gets
1003          * set if we enable XSAVE and we enable PKU in XCR0.
1004          */
1005         if (!boot_cpu_has(X86_FEATURE_OSPKE))
1006                 return -EINVAL;
1007
1008         /*
1009          * This code should only be called with valid 'pkey'
1010          * values originating from in-kernel users.  Complain
1011          * if a bad value is observed.
1012          */
1013         WARN_ON_ONCE(pkey >= arch_max_pkey());
1014
1015         /* Set the bits we need in PKRU:  */
1016         if (init_val & PKEY_DISABLE_ACCESS)
1017                 new_pkru_bits |= PKRU_AD_BIT;
1018         if (init_val & PKEY_DISABLE_WRITE)
1019                 new_pkru_bits |= PKRU_WD_BIT;
1020
1021         /* Shift the bits in to the correct place in PKRU for pkey: */
1022         new_pkru_bits <<= pkey_shift;
1023
1024         /* Get old PKRU and mask off any old bits in place: */
1025         old_pkru = read_pkru();
1026         old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
1027
1028         /* Write old part along with new part: */
1029         write_pkru(old_pkru | new_pkru_bits);
1030
1031         return 0;
1032 }
1033 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
1034
1035 /*
1036  * Weird legacy quirk: SSE and YMM states store information in the
1037  * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
1038  * area is marked as unused in the xfeatures header, we need to copy
1039  * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
1040  */
1041 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
1042 {
1043         if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
1044                 return false;
1045
1046         if (xfeatures & XFEATURE_MASK_FP)
1047                 return false;
1048
1049         return true;
1050 }
1051
1052 static void fill_gap(struct membuf *to, unsigned *last, unsigned offset)
1053 {
1054         if (*last >= offset)
1055                 return;
1056         membuf_write(to, (void *)&init_fpstate.xsave + *last, offset - *last);
1057         *last = offset;
1058 }
1059
1060 static void copy_part(struct membuf *to, unsigned *last, unsigned offset,
1061                       unsigned size, void *from)
1062 {
1063         fill_gap(to, last, offset);
1064         membuf_write(to, from, size);
1065         *last = offset + size;
1066 }
1067
1068 /*
1069  * Convert from kernel XSAVES compacted format to standard format and copy
1070  * to a kernel-space ptrace buffer.
1071  *
1072  * It supports partial copy but pos always starts from zero. This is called
1073  * from xstateregs_get() and there we check the CPU has XSAVES.
1074  */
1075 void copy_xstate_to_kernel(struct membuf to, struct xregs_state *xsave)
1076 {
1077         struct xstate_header header;
1078         const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
1079         unsigned size = to.left;
1080         unsigned last = 0;
1081         int i;
1082
1083         /*
1084          * The destination is a ptrace buffer; we put in only user xstates:
1085          */
1086         memset(&header, 0, sizeof(header));
1087         header.xfeatures = xsave->header.xfeatures;
1088         header.xfeatures &= xfeatures_mask_user();
1089
1090         if (header.xfeatures & XFEATURE_MASK_FP)
1091                 copy_part(&to, &last, 0, off_mxcsr, &xsave->i387);
1092         if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
1093                 copy_part(&to, &last, off_mxcsr,
1094                           MXCSR_AND_FLAGS_SIZE, &xsave->i387.mxcsr);
1095         if (header.xfeatures & XFEATURE_MASK_FP)
1096                 copy_part(&to, &last, offsetof(struct fxregs_state, st_space),
1097                           128, &xsave->i387.st_space);
1098         if (header.xfeatures & XFEATURE_MASK_SSE)
1099                 copy_part(&to, &last, xstate_offsets[XFEATURE_SSE],
1100                           256, &xsave->i387.xmm_space);
1101         /*
1102          * Fill xsave->i387.sw_reserved value for ptrace frame:
1103          */
1104         copy_part(&to, &last, offsetof(struct fxregs_state, sw_reserved),
1105                   48, xstate_fx_sw_bytes);
1106         /*
1107          * Copy xregs_state->header:
1108          */
1109         copy_part(&to, &last, offsetof(struct xregs_state, header),
1110                   sizeof(header), &header);
1111
1112         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
1113                 /*
1114                  * Copy only in-use xstates:
1115                  */
1116                 if ((header.xfeatures >> i) & 1) {
1117                         void *src = __raw_xsave_addr(xsave, i);
1118
1119                         copy_part(&to, &last, xstate_offsets[i],
1120                                   xstate_sizes[i], src);
1121                 }
1122
1123         }
1124         fill_gap(&to, &last, size);
1125 }
1126
1127 /*
1128  * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
1129  * and copy to the target thread. This is called from xstateregs_set().
1130  */
1131 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
1132 {
1133         unsigned int offset, size;
1134         int i;
1135         struct xstate_header hdr;
1136
1137         offset = offsetof(struct xregs_state, header);
1138         size = sizeof(hdr);
1139
1140         memcpy(&hdr, kbuf + offset, size);
1141
1142         if (validate_user_xstate_header(&hdr))
1143                 return -EINVAL;
1144
1145         for (i = 0; i < XFEATURE_MAX; i++) {
1146                 u64 mask = ((u64)1 << i);
1147
1148                 if (hdr.xfeatures & mask) {
1149                         void *dst = __raw_xsave_addr(xsave, i);
1150
1151                         offset = xstate_offsets[i];
1152                         size = xstate_sizes[i];
1153
1154                         memcpy(dst, kbuf + offset, size);
1155                 }
1156         }
1157
1158         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1159                 offset = offsetof(struct fxregs_state, mxcsr);
1160                 size = MXCSR_AND_FLAGS_SIZE;
1161                 memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
1162         }
1163
1164         /*
1165          * The state that came in from userspace was user-state only.
1166          * Mask all the user states out of 'xfeatures':
1167          */
1168         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
1169
1170         /*
1171          * Add back in the features that came in from userspace:
1172          */
1173         xsave->header.xfeatures |= hdr.xfeatures;
1174
1175         return 0;
1176 }
1177
1178 /*
1179  * Convert from a ptrace or sigreturn standard-format user-space buffer to
1180  * kernel XSAVES format and copy to the target thread. This is called from
1181  * xstateregs_set(), as well as potentially from the sigreturn() and
1182  * rt_sigreturn() system calls.
1183  */
1184 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
1185 {
1186         unsigned int offset, size;
1187         int i;
1188         struct xstate_header hdr;
1189
1190         offset = offsetof(struct xregs_state, header);
1191         size = sizeof(hdr);
1192
1193         if (__copy_from_user(&hdr, ubuf + offset, size))
1194                 return -EFAULT;
1195
1196         if (validate_user_xstate_header(&hdr))
1197                 return -EINVAL;
1198
1199         for (i = 0; i < XFEATURE_MAX; i++) {
1200                 u64 mask = ((u64)1 << i);
1201
1202                 if (hdr.xfeatures & mask) {
1203                         void *dst = __raw_xsave_addr(xsave, i);
1204
1205                         offset = xstate_offsets[i];
1206                         size = xstate_sizes[i];
1207
1208                         if (__copy_from_user(dst, ubuf + offset, size))
1209                                 return -EFAULT;
1210                 }
1211         }
1212
1213         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1214                 offset = offsetof(struct fxregs_state, mxcsr);
1215                 size = MXCSR_AND_FLAGS_SIZE;
1216                 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
1217                         return -EFAULT;
1218         }
1219
1220         /*
1221          * The state that came in from userspace was user-state only.
1222          * Mask all the user states out of 'xfeatures':
1223          */
1224         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR_ALL;
1225
1226         /*
1227          * Add back in the features that came in from userspace:
1228          */
1229         xsave->header.xfeatures |= hdr.xfeatures;
1230
1231         return 0;
1232 }
1233
1234 /*
1235  * Save only supervisor states to the kernel buffer.  This blows away all
1236  * old states, and is intended to be used only in __fpu__restore_sig(), where
1237  * user states are restored from the user buffer.
1238  */
1239 void copy_supervisor_to_kernel(struct xregs_state *xstate)
1240 {
1241         struct xstate_header *header;
1242         u64 max_bit, min_bit;
1243         u32 lmask, hmask;
1244         int err, i;
1245
1246         if (WARN_ON(!boot_cpu_has(X86_FEATURE_XSAVES)))
1247                 return;
1248
1249         if (!xfeatures_mask_supervisor())
1250                 return;
1251
1252         max_bit = __fls(xfeatures_mask_supervisor());
1253         min_bit = __ffs(xfeatures_mask_supervisor());
1254
1255         lmask = xfeatures_mask_supervisor();
1256         hmask = xfeatures_mask_supervisor() >> 32;
1257         XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
1258
1259         /* We should never fault when copying to a kernel buffer: */
1260         if (WARN_ON_FPU(err))
1261                 return;
1262
1263         /*
1264          * At this point, the buffer has only supervisor states and must be
1265          * converted back to normal kernel format.
1266          */
1267         header = &xstate->header;
1268         header->xcomp_bv |= xfeatures_mask_all;
1269
1270         /*
1271          * This only moves states up in the buffer.  Start with
1272          * the last state and move backwards so that states are
1273          * not overwritten until after they are moved.  Note:
1274          * memmove() allows overlapping src/dst buffers.
1275          */
1276         for (i = max_bit; i >= min_bit; i--) {
1277                 u8 *xbuf = (u8 *)xstate;
1278
1279                 if (!((header->xfeatures >> i) & 1))
1280                         continue;
1281
1282                 /* Move xfeature 'i' into its normal location */
1283                 memmove(xbuf + xstate_comp_offsets[i],
1284                         xbuf + xstate_supervisor_only_offsets[i],
1285                         xstate_sizes[i]);
1286         }
1287 }
1288
1289 /**
1290  * copy_dynamic_supervisor_to_kernel() - Save dynamic supervisor states to
1291  *                                       an xsave area
1292  * @xstate: A pointer to an xsave area
1293  * @mask: Represent the dynamic supervisor features saved into the xsave area
1294  *
1295  * Only the dynamic supervisor states sets in the mask are saved into the xsave
1296  * area (See the comment in XFEATURE_MASK_DYNAMIC for the details of dynamic
1297  * supervisor feature). Besides the dynamic supervisor states, the legacy
1298  * region and XSAVE header are also saved into the xsave area. The supervisor
1299  * features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
1300  * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not saved.
1301  *
1302  * The xsave area must be 64-bytes aligned.
1303  */
1304 void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask)
1305 {
1306         u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
1307         u32 lmask, hmask;
1308         int err;
1309
1310         if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES)))
1311                 return;
1312
1313         if (WARN_ON_FPU(!dynamic_mask))
1314                 return;
1315
1316         lmask = dynamic_mask;
1317         hmask = dynamic_mask >> 32;
1318
1319         XSTATE_OP(XSAVES, xstate, lmask, hmask, err);
1320
1321         /* Should never fault when copying to a kernel buffer */
1322         WARN_ON_FPU(err);
1323 }
1324
1325 /**
1326  * copy_kernel_to_dynamic_supervisor() - Restore dynamic supervisor states from
1327  *                                       an xsave area
1328  * @xstate: A pointer to an xsave area
1329  * @mask: Represent the dynamic supervisor features restored from the xsave area
1330  *
1331  * Only the dynamic supervisor states sets in the mask are restored from the
1332  * xsave area (See the comment in XFEATURE_MASK_DYNAMIC for the details of
1333  * dynamic supervisor feature). Besides the dynamic supervisor states, the
1334  * legacy region and XSAVE header are also restored from the xsave area. The
1335  * supervisor features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
1336  * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not restored.
1337  *
1338  * The xsave area must be 64-bytes aligned.
1339  */
1340 void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask)
1341 {
1342         u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
1343         u32 lmask, hmask;
1344         int err;
1345
1346         if (WARN_ON_FPU(!boot_cpu_has(X86_FEATURE_XSAVES)))
1347                 return;
1348
1349         if (WARN_ON_FPU(!dynamic_mask))
1350                 return;
1351
1352         lmask = dynamic_mask;
1353         hmask = dynamic_mask >> 32;
1354
1355         XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
1356
1357         /* Should never fault when copying from a kernel buffer */
1358         WARN_ON_FPU(err);
1359 }
1360
1361 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1362 /*
1363  * Report the amount of time elapsed in millisecond since last AVX512
1364  * use in the task.
1365  */
1366 static void avx512_status(struct seq_file *m, struct task_struct *task)
1367 {
1368         unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1369         long delta;
1370
1371         if (!timestamp) {
1372                 /*
1373                  * Report -1 if no AVX512 usage
1374                  */
1375                 delta = -1;
1376         } else {
1377                 delta = (long)(jiffies - timestamp);
1378                 /*
1379                  * Cap to LONG_MAX if time difference > LONG_MAX
1380                  */
1381                 if (delta < 0)
1382                         delta = LONG_MAX;
1383                 delta = jiffies_to_msecs(delta);
1384         }
1385
1386         seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1387         seq_putc(m, '\n');
1388 }
1389
1390 /*
1391  * Report architecture specific information
1392  */
1393 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1394                         struct pid *pid, struct task_struct *task)
1395 {
1396         /*
1397          * Report AVX512 state if the processor and build option supported.
1398          */
1399         if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1400                 avx512_status(m, task);
1401
1402         return 0;
1403 }
1404 #endif /* CONFIG_PROC_PID_ARCH_STATUS */