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[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  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[XFEATURE_FP]     = 0;
 258         xstate_sizes[XFEATURE_FP]       = offsetof(struct fxregs_state,
 259                                                    xmm_space);
 260
 261         xstate_offsets[XFEATURE_SSE]    = xstate_sizes[XFEATURE_FP];
 262         xstate_sizes[XFEATURE_SSE]      = sizeof_field(struct fxregs_state,
 263                                                        xmm_space);
 264
 265         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 266                 if (!xfeature_enabled(i))
 267                         continue;
 268
 269                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 270
 271                 /*
 272                  * If an xfeature is supervisor state, the offset
 273                  * in EBX is invalid. We leave it to -1.
 274                  */
 275                 if (xfeature_is_user(i))
 276                         xstate_offsets[i] = ebx;
 277
 278                 xstate_sizes[i] = eax;
 279                 /*
 280                  * In our xstate size checks, we assume that the
 281                  * highest-numbered xstate feature has the
 282                  * highest offset in the buffer.  Ensure it does.
 283                  */
 284                 WARN_ONCE(last_good_offset > xstate_offsets[i],
 285                         "x86/fpu: misordered xstate at %d\n", last_good_offset);
 286                 last_good_offset = xstate_offsets[i];
 287         }
 288 }
 289
 290 static void __init print_xstate_feature(u64 xstate_mask)
 291 {
 292         const char *feature_name;
 293
 294         if (cpu_has_xfeatures(xstate_mask, &feature_name))
 295                 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
 296 }
 297
 298 /*
 299  * Print out all the supported xstate features:
 300  */
 301 static void __init print_xstate_features(void)
 302 {
 303         print_xstate_feature(XFEATURE_MASK_FP);
 304         print_xstate_feature(XFEATURE_MASK_SSE);
 305         print_xstate_feature(XFEATURE_MASK_YMM);
 306         print_xstate_feature(XFEATURE_MASK_BNDREGS);
 307         print_xstate_feature(XFEATURE_MASK_BNDCSR);
 308         print_xstate_feature(XFEATURE_MASK_OPMASK);
 309         print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
 310         print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
 311         print_xstate_feature(XFEATURE_MASK_PKRU);
 312 }
 313
 314 /*
 315  * This check is important because it is easy to get XSTATE_*
 316  * confused with XSTATE_BIT_*.
 317  */
 318 #define CHECK_XFEATURE(nr) do {         \
 319         WARN_ON(nr < FIRST_EXTENDED_XFEATURE);  \
 320         WARN_ON(nr >= XFEATURE_MAX);    \
 321 } while (0)
 322
 323 /*
 324  * We could cache this like xstate_size[], but we only use
 325  * it here, so it would be a waste of space.
 326  */
 327 static int xfeature_is_aligned(int xfeature_nr)
 328 {
 329         u32 eax, ebx, ecx, edx;
 330
 331         CHECK_XFEATURE(xfeature_nr);
 332         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 333         /*
 334          * The value returned by ECX[1] indicates the alignment
 335          * of state component 'i' when the compacted format
 336          * of the extended region of an XSAVE area is used:
 337          */
 338         return !!(ecx & 2);
 339 }
 340
 341 /*
 342  * This function sets up offsets and sizes of all extended states in
 343  * xsave area. This supports both standard format and compacted format
 344  * of the xsave aread.
 345  */
 346 static void __init setup_xstate_comp(void)
 347 {
 348         unsigned int xstate_comp_sizes[XFEATURE_MAX];
 349         int i;
 350
 351         /*
 352          * The FP xstates and SSE xstates are legacy states. They are always
 353          * in the fixed offsets in the xsave area in either compacted form
 354          * or standard form.
 355          */
 356         xstate_comp_offsets[XFEATURE_FP] = 0;
 357         xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
 358                                                      xmm_space);
 359
 360         if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
 361                 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 362                         if (xfeature_enabled(i)) {
 363                                 xstate_comp_offsets[i] = xstate_offsets[i];
 364                                 xstate_comp_sizes[i] = xstate_sizes[i];
 365                         }
 366                 }
 367                 return;
 368         }
 369
 370         xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
 371                 FXSAVE_SIZE + XSAVE_HDR_SIZE;
 372
 373         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 374                 if (xfeature_enabled(i))
 375                         xstate_comp_sizes[i] = xstate_sizes[i];
 376                 else
 377                         xstate_comp_sizes[i] = 0;
 378
 379                 if (i > FIRST_EXTENDED_XFEATURE) {
 380                         xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
 381                                         + xstate_comp_sizes[i-1];
 382
 383                         if (xfeature_is_aligned(i))
 384                                 xstate_comp_offsets[i] =
 385                                         ALIGN(xstate_comp_offsets[i], 64);
 386                 }
 387         }
 388 }
 389
 390 /*
 391  * Print out xstate component offsets and sizes
 392  */
 393 static void __init print_xstate_offset_size(void)
 394 {
 395         int i;
 396
 397         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 398                 if (!xfeature_enabled(i))
 399                         continue;
 400                 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
 401                          i, xstate_comp_offsets[i], i, xstate_sizes[i]);
 402         }
 403 }
 404
 405 /*
 406  * setup the xstate image representing the init state
 407  */
 408 static void __init setup_init_fpu_buf(void)
 409 {
 410         static int on_boot_cpu __initdata = 1;
 411
 412         WARN_ON_FPU(!on_boot_cpu);
 413         on_boot_cpu = 0;
 414
 415         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 416                 return;
 417
 418         setup_xstate_features();
 419         print_xstate_features();
 420
 421         if (boot_cpu_has(X86_FEATURE_XSAVES))
 422                 init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask;
 423
 424         /*
 425          * Init all the features state with header.xfeatures being 0x0
 426          */
 427         copy_kernel_to_xregs_booting(&init_fpstate.xsave);
 428
 429         /*
 430          * Dump the init state again. This is to identify the init state
 431          * of any feature which is not represented by all zero's.
 432          */
 433         copy_xregs_to_kernel_booting(&init_fpstate.xsave);
 434 }
 435
 436 static int xfeature_uncompacted_offset(int xfeature_nr)
 437 {
 438         u32 eax, ebx, ecx, edx;
 439
 440         /*
 441          * Only XSAVES supports supervisor states and it uses compacted
 442          * format. Checking a supervisor state's uncompacted offset is
 443          * an error.
 444          */
 445         if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) {
 446                 WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
 447                 return -1;
 448         }
 449
 450         CHECK_XFEATURE(xfeature_nr);
 451         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 452         return ebx;
 453 }
 454
 455 static int xfeature_size(int xfeature_nr)
 456 {
 457         u32 eax, ebx, ecx, edx;
 458
 459         CHECK_XFEATURE(xfeature_nr);
 460         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 461         return eax;
 462 }
 463
 464 /*
 465  * 'XSAVES' implies two different things:
 466  * 1. saving of supervisor/system state
 467  * 2. using the compacted format
 468  *
 469  * Use this function when dealing with the compacted format so
 470  * that it is obvious which aspect of 'XSAVES' is being handled
 471  * by the calling code.
 472  */
 473 int using_compacted_format(void)
 474 {
 475         return boot_cpu_has(X86_FEATURE_XSAVES);
 476 }
 477
 478 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */
 479 int validate_xstate_header(const struct xstate_header *hdr)
 480 {
 481         /* No unknown or supervisor features may be set */
 482         if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR))
 483                 return -EINVAL;
 484
 485         /* Userspace must use the uncompacted format */
 486         if (hdr->xcomp_bv)
 487                 return -EINVAL;
 488
 489         /*
 490          * If 'reserved' is shrunken to add a new field, make sure to validate
 491          * that new field here!
 492          */
 493         BUILD_BUG_ON(sizeof(hdr->reserved) != 48);
 494
 495         /* No reserved bits may be set */
 496         if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
 497                 return -EINVAL;
 498
 499         return 0;
 500 }
 501
 502 static void __xstate_dump_leaves(void)
 503 {
 504         int i;
 505         u32 eax, ebx, ecx, edx;
 506         static int should_dump = 1;
 507
 508         if (!should_dump)
 509                 return;
 510         should_dump = 0;
 511         /*
 512          * Dump out a few leaves past the ones that we support
 513          * just in case there are some goodies up there
 514          */
 515         for (i = 0; i < XFEATURE_MAX + 10; i++) {
 516                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 517                 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n",
 518                         XSTATE_CPUID, i, eax, ebx, ecx, edx);
 519         }
 520 }
 521
 522 #define XSTATE_WARN_ON(x) do {                                                  \
 523         if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) {        \
 524                 __xstate_dump_leaves();                                         \
 525         }                                                                       \
 526 } while (0)
 527
 528 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do {                      \
 529         if ((nr == nr_macro) &&                                         \
 530             WARN_ONCE(sz != sizeof(__struct),                           \
 531                 "%s: struct is %zu bytes, cpu state %d bytes\n",        \
 532                 __stringify(nr_macro), sizeof(__struct), sz)) {         \
 533                 __xstate_dump_leaves();                                 \
 534         }                                                               \
 535 } while (0)
 536
 537 /*
 538  * We have a C struct for each 'xstate'.  We need to ensure
 539  * that our software representation matches what the CPU
 540  * tells us about the state's size.
 541  */
 542 static void check_xstate_against_struct(int nr)
 543 {
 544         /*
 545          * Ask the CPU for the size of the state.
 546          */
 547         int sz = xfeature_size(nr);
 548         /*
 549          * Match each CPU state with the corresponding software
 550          * structure.
 551          */
 552         XCHECK_SZ(sz, nr, XFEATURE_YMM,       struct ymmh_struct);
 553         XCHECK_SZ(sz, nr, XFEATURE_BNDREGS,   struct mpx_bndreg_state);
 554         XCHECK_SZ(sz, nr, XFEATURE_BNDCSR,    struct mpx_bndcsr_state);
 555         XCHECK_SZ(sz, nr, XFEATURE_OPMASK,    struct avx_512_opmask_state);
 556         XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state);
 557         XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM,  struct avx_512_hi16_state);
 558         XCHECK_SZ(sz, nr, XFEATURE_PKRU,      struct pkru_state);
 559
 560         /*
 561          * Make *SURE* to add any feature numbers in below if
 562          * there are "holes" in the xsave state component
 563          * numbers.
 564          */
 565         if ((nr < XFEATURE_YMM) ||
 566             (nr >= XFEATURE_MAX) ||
 567             (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) {
 568                 WARN_ONCE(1, "no structure for xstate: %d\n", nr);
 569                 XSTATE_WARN_ON(1);
 570         }
 571 }
 572
 573 /*
 574  * This essentially double-checks what the cpu told us about
 575  * how large the XSAVE buffer needs to be.  We are recalculating
 576  * it to be safe.
 577  */
 578 static void do_extra_xstate_size_checks(void)
 579 {
 580         int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
 581         int i;
 582
 583         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 584                 if (!xfeature_enabled(i))
 585                         continue;
 586
 587                 check_xstate_against_struct(i);
 588                 /*
 589                  * Supervisor state components can be managed only by
 590                  * XSAVES, which is compacted-format only.
 591                  */
 592                 if (!using_compacted_format())
 593                         XSTATE_WARN_ON(xfeature_is_supervisor(i));
 594
 595                 /* Align from the end of the previous feature */
 596                 if (xfeature_is_aligned(i))
 597                         paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64);
 598                 /*
 599                  * The offset of a given state in the non-compacted
 600                  * format is given to us in a CPUID leaf.  We check
 601                  * them for being ordered (increasing offsets) in
 602                  * setup_xstate_features().
 603                  */
 604                 if (!using_compacted_format())
 605                         paranoid_xstate_size = xfeature_uncompacted_offset(i);
 606                 /*
 607                  * The compacted-format offset always depends on where
 608                  * the previous state ended.
 609                  */
 610                 paranoid_xstate_size += xfeature_size(i);
 611         }
 612         XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size);
 613 }
 614
 615
 616 /*
 617  * Get total size of enabled xstates in XCR0/xfeatures_mask.
 618  *
 619  * Note the SDM's wording here.  "sub-function 0" only enumerates
 620  * the size of the *user* states.  If we use it to size a buffer
 621  * that we use 'XSAVES' on, we could potentially overflow the
 622  * buffer because 'XSAVES' saves system states too.
 623  *
 624  * Note that we do not currently set any bits on IA32_XSS so
 625  * 'XCR0 | IA32_XSS == XCR0' for now.
 626  */
 627 static unsigned int __init get_xsaves_size(void)
 628 {
 629         unsigned int eax, ebx, ecx, edx;
 630         /*
 631          * - CPUID function 0DH, sub-function 1:
 632          *    EBX enumerates the size (in bytes) required by
 633          *    the XSAVES instruction for an XSAVE area
 634          *    containing all the state components
 635          *    corresponding to bits currently set in
 636          *    XCR0 | IA32_XSS.
 637          */
 638         cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx);
 639         return ebx;
 640 }
 641
 642 static unsigned int __init get_xsave_size(void)
 643 {
 644         unsigned int eax, ebx, ecx, edx;
 645         /*
 646          * - CPUID function 0DH, sub-function 0:
 647          *    EBX enumerates the size (in bytes) required by
 648          *    the XSAVE instruction for an XSAVE area
 649          *    containing all the *user* state components
 650          *    corresponding to bits currently set in XCR0.
 651          */
 652         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 653         return ebx;
 654 }
 655
 656 /*
 657  * Will the runtime-enumerated 'xstate_size' fit in the init
 658  * task's statically-allocated buffer?
 659  */
 660 static bool is_supported_xstate_size(unsigned int test_xstate_size)
 661 {
 662         if (test_xstate_size <= sizeof(union fpregs_state))
 663                 return true;
 664
 665         pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n",
 666                         sizeof(union fpregs_state), test_xstate_size);
 667         return false;
 668 }
 669
 670 static int __init init_xstate_size(void)
 671 {
 672         /* Recompute the context size for enabled features: */
 673         unsigned int possible_xstate_size;
 674         unsigned int xsave_size;
 675
 676         xsave_size = get_xsave_size();
 677
 678         if (boot_cpu_has(X86_FEATURE_XSAVES))
 679                 possible_xstate_size = get_xsaves_size();
 680         else
 681                 possible_xstate_size = xsave_size;
 682
 683         /* Ensure we have the space to store all enabled: */
 684         if (!is_supported_xstate_size(possible_xstate_size))
 685                 return -EINVAL;
 686
 687         /*
 688          * The size is OK, we are definitely going to use xsave,
 689          * make it known to the world that we need more space.
 690          */
 691         fpu_kernel_xstate_size = possible_xstate_size;
 692         do_extra_xstate_size_checks();
 693
 694         /*
 695          * User space is always in standard format.
 696          */
 697         fpu_user_xstate_size = xsave_size;
 698         return 0;
 699 }
 700
 701 /*
 702  * We enabled the XSAVE hardware, but something went wrong and
 703  * we can not use it.  Disable it.
 704  */
 705 static void fpu__init_disable_system_xstate(void)
 706 {
 707         xfeatures_mask = 0;
 708         cr4_clear_bits(X86_CR4_OSXSAVE);
 709         setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 710 }
 711
 712 /*
 713  * Enable and initialize the xsave feature.
 714  * Called once per system bootup.
 715  */
 716 void __init fpu__init_system_xstate(void)
 717 {
 718         unsigned int eax, ebx, ecx, edx;
 719         static int on_boot_cpu __initdata = 1;
 720         int err;
 721         int i;
 722
 723         WARN_ON_FPU(!on_boot_cpu);
 724         on_boot_cpu = 0;
 725
 726         if (!boot_cpu_has(X86_FEATURE_FPU)) {
 727                 pr_info("x86/fpu: No FPU detected\n");
 728                 return;
 729         }
 730
 731         if (!boot_cpu_has(X86_FEATURE_XSAVE)) {
 732                 pr_info("x86/fpu: x87 FPU will use %s\n",
 733                         boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE");
 734                 return;
 735         }
 736
 737         if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
 738                 WARN_ON_FPU(1);
 739                 return;
 740         }
 741
 742         cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
 743         xfeatures_mask = eax + ((u64)edx << 32);
 744
 745         if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
 746                 /*
 747                  * This indicates that something really unexpected happened
 748                  * with the enumeration.  Disable XSAVE and try to continue
 749                  * booting without it.  This is too early to BUG().
 750                  */
 751                 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask);
 752                 goto out_disable;
 753         }
 754
 755         /*
 756          * Clear XSAVE features that are disabled in the normal CPUID.
 757          */
 758         for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) {
 759                 if (!boot_cpu_has(xsave_cpuid_features[i]))
 760                         xfeatures_mask &= ~BIT(i);
 761         }
 762
 763         xfeatures_mask &= fpu__get_supported_xfeatures_mask();
 764
 765         /* Enable xstate instructions to be able to continue with initialization: */
 766         fpu__init_cpu_xstate();
 767         err = init_xstate_size();
 768         if (err)
 769                 goto out_disable;
 770
 771         /*
 772          * Update info used for ptrace frames; use standard-format size and no
 773          * supervisor xstates:
 774          */
 775         update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR);
 776
 777         fpu__init_prepare_fx_sw_frame();
 778         setup_init_fpu_buf();
 779         setup_xstate_comp();
 780         print_xstate_offset_size();
 781
 782         pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
 783                 xfeatures_mask,
 784                 fpu_kernel_xstate_size,
 785                 boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard");
 786         return;
 787
 788 out_disable:
 789         /* something went wrong, try to boot without any XSAVE support */
 790         fpu__init_disable_system_xstate();
 791 }
 792
 793 /*
 794  * Restore minimal FPU state after suspend:
 795  */
 796 void fpu__resume_cpu(void)
 797 {
 798         /*
 799          * Restore XCR0 on xsave capable CPUs:
 800          */
 801         if (boot_cpu_has(X86_FEATURE_XSAVE))
 802                 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
 803 }
 804
 805 /*
 806  * Given an xstate feature nr, calculate where in the xsave
 807  * buffer the state is.  Callers should ensure that the buffer
 808  * is valid.
 809  */
 810 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 811 {
 812         if (!xfeature_enabled(xfeature_nr)) {
 813                 WARN_ON_FPU(1);
 814                 return NULL;
 815         }
 816
 817         return (void *)xsave + xstate_comp_offsets[xfeature_nr];
 818 }
 819 /*
 820  * Given the xsave area and a state inside, this function returns the
 821  * address of the state.
 822  *
 823  * This is the API that is called to get xstate address in either
 824  * standard format or compacted format of xsave area.
 825  *
 826  * Note that if there is no data for the field in the xsave buffer
 827  * this will return NULL.
 828  *
 829  * Inputs:
 830  *      xstate: the thread's storage area for all FPU data
 831  *      xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 832  *      XFEATURE_SSE, etc...)
 833  * Output:
 834  *      address of the state in the xsave area, or NULL if the
 835  *      field is not present in the xsave buffer.
 836  */
 837 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 838 {
 839         /*
 840          * Do we even *have* xsave state?
 841          */
 842         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 843                 return NULL;
 844
 845         /*
 846          * We should not ever be requesting features that we
 847          * have not enabled.  Remember that xfeatures_mask is
 848          * what we write to the XCR0 register.
 849          */
 850         WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)),
 851                   "get of unsupported state");
 852         /*
 853          * This assumes the last 'xsave*' instruction to
 854          * have requested that 'xfeature_nr' be saved.
 855          * If it did not, we might be seeing and old value
 856          * of the field in the buffer.
 857          *
 858          * This can happen because the last 'xsave' did not
 859          * request that this feature be saved (unlikely)
 860          * or because the "init optimization" caused it
 861          * to not be saved.
 862          */
 863         if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
 864                 return NULL;
 865
 866         return __raw_xsave_addr(xsave, xfeature_nr);
 867 }
 868 EXPORT_SYMBOL_GPL(get_xsave_addr);
 869
 870 /*
 871  * This wraps up the common operations that need to occur when retrieving
 872  * data from xsave state.  It first ensures that the current task was
 873  * using the FPU and retrieves the data in to a buffer.  It then calculates
 874  * the offset of the requested field in the buffer.
 875  *
 876  * This function is safe to call whether the FPU is in use or not.
 877  *
 878  * Note that this only works on the current task.
 879  *
 880  * Inputs:
 881  *      @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
 882  *      XFEATURE_SSE, etc...)
 883  * Output:
 884  *      address of the state in the xsave area or NULL if the state
 885  *      is not present or is in its 'init state'.
 886  */
 887 const void *get_xsave_field_ptr(int xfeature_nr)
 888 {
 889         struct fpu *fpu = &current->thread.fpu;
 890
 891         /*
 892          * fpu__save() takes the CPU's xstate registers
 893          * and saves them off to the 'fpu memory buffer.
 894          */
 895         fpu__save(fpu);
 896
 897         return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
 898 }
 899
 900 #ifdef CONFIG_ARCH_HAS_PKEYS
 901
 902 #define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2)
 903 #define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1)
 904 /*
 905  * This will go out and modify PKRU register to set the access
 906  * rights for @pkey to @init_val.
 907  */
 908 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 909                 unsigned long init_val)
 910 {
 911         u32 old_pkru;
 912         int pkey_shift = (pkey * PKRU_BITS_PER_PKEY);
 913         u32 new_pkru_bits = 0;
 914
 915         /*
 916          * This check implies XSAVE support.  OSPKE only gets
 917          * set if we enable XSAVE and we enable PKU in XCR0.
 918          */
 919         if (!boot_cpu_has(X86_FEATURE_OSPKE))
 920                 return -EINVAL;
 921
 922         /* Set the bits we need in PKRU:  */
 923         if (init_val & PKEY_DISABLE_ACCESS)
 924                 new_pkru_bits |= PKRU_AD_BIT;
 925         if (init_val & PKEY_DISABLE_WRITE)
 926                 new_pkru_bits |= PKRU_WD_BIT;
 927
 928         /* Shift the bits in to the correct place in PKRU for pkey: */
 929         new_pkru_bits <<= pkey_shift;
 930
 931         /* Get old PKRU and mask off any old bits in place: */
 932         old_pkru = read_pkru();
 933         old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
 934
 935         /* Write old part along with new part: */
 936         write_pkru(old_pkru | new_pkru_bits);
 937
 938         return 0;
 939 }
 940 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
 941
 942 /*
 943  * Weird legacy quirk: SSE and YMM states store information in the
 944  * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
 945  * area is marked as unused in the xfeatures header, we need to copy
 946  * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
 947  */
 948 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
 949 {
 950         if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
 951                 return false;
 952
 953         if (xfeatures & XFEATURE_MASK_FP)
 954                 return false;
 955
 956         return true;
 957 }
 958
 959 /*
 960  * This is similar to user_regset_copyout(), but will not add offset to
 961  * the source data pointer or increment pos, count, kbuf, and ubuf.
 962  */
 963 static inline void
 964 __copy_xstate_to_kernel(void *kbuf, const void *data,
 965                         unsigned int offset, unsigned int size, unsigned int size_total)
 966 {
 967         if (offset < size_total) {
 968                 unsigned int copy = min(size, size_total - offset);
 969
 970                 memcpy(kbuf + offset, data, copy);
 971         }
 972 }
 973
 974 /*
 975  * Convert from kernel XSAVES compacted format to standard format and copy
 976  * to a kernel-space ptrace buffer.
 977  *
 978  * It supports partial copy but pos always starts from zero. This is called
 979  * from xstateregs_get() and there we check the CPU has XSAVES.
 980  */
 981 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
 982 {
 983         unsigned int offset, size;
 984         struct xstate_header header;
 985         int i;
 986
 987         /*
 988          * Currently copy_regset_to_user() starts from pos 0:
 989          */
 990         if (unlikely(offset_start != 0))
 991                 return -EFAULT;
 992
 993         /*
 994          * The destination is a ptrace buffer; we put in only user xstates:
 995          */
 996         memset(&header, 0, sizeof(header));
 997         header.xfeatures = xsave->header.xfeatures;
 998         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
 999
1000         /*
1001          * Copy xregs_state->header:
1002          */
1003         offset = offsetof(struct xregs_state, header);
1004         size = sizeof(header);
1005
1006         __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total);
1007
1008         for (i = 0; i < XFEATURE_MAX; i++) {
1009                 /*
1010                  * Copy only in-use xstates:
1011                  */
1012                 if ((header.xfeatures >> i) & 1) {
1013                         void *src = __raw_xsave_addr(xsave, i);
1014
1015                         offset = xstate_offsets[i];
1016                         size = xstate_sizes[i];
1017
1018                         /* The next component has to fit fully into the output buffer: */
1019                         if (offset + size > size_total)
1020                                 break;
1021
1022                         __copy_xstate_to_kernel(kbuf, src, offset, size, size_total);
1023                 }
1024
1025         }
1026
1027         if (xfeatures_mxcsr_quirk(header.xfeatures)) {
1028                 offset = offsetof(struct fxregs_state, mxcsr);
1029                 size = MXCSR_AND_FLAGS_SIZE;
1030                 __copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total);
1031         }
1032
1033         /*
1034          * Fill xsave->i387.sw_reserved value for ptrace frame:
1035          */
1036         offset = offsetof(struct fxregs_state, sw_reserved);
1037         size = sizeof(xstate_fx_sw_bytes);
1038
1039         __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total);
1040
1041         return 0;
1042 }
1043
1044 static inline int
1045 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total)
1046 {
1047         if (!size)
1048                 return 0;
1049
1050         if (offset < size_total) {
1051                 unsigned int copy = min(size, size_total - offset);
1052
1053                 if (__copy_to_user(ubuf + offset, data, copy))
1054                         return -EFAULT;
1055         }
1056         return 0;
1057 }
1058
1059 /*
1060  * Convert from kernel XSAVES compacted format to standard format and copy
1061  * to a user-space buffer. It supports partial copy but pos always starts from
1062  * zero. This is called from xstateregs_get() and there we check the CPU
1063  * has XSAVES.
1064  */
1065 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
1066 {
1067         unsigned int offset, size;
1068         int ret, i;
1069         struct xstate_header header;
1070
1071         /*
1072          * Currently copy_regset_to_user() starts from pos 0:
1073          */
1074         if (unlikely(offset_start != 0))
1075                 return -EFAULT;
1076
1077         /*
1078          * The destination is a ptrace buffer; we put in only user xstates:
1079          */
1080         memset(&header, 0, sizeof(header));
1081         header.xfeatures = xsave->header.xfeatures;
1082         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
1083
1084         /*
1085          * Copy xregs_state->header:
1086          */
1087         offset = offsetof(struct xregs_state, header);
1088         size = sizeof(header);
1089
1090         ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total);
1091         if (ret)
1092                 return ret;
1093
1094         for (i = 0; i < XFEATURE_MAX; i++) {
1095                 /*
1096                  * Copy only in-use xstates:
1097                  */
1098                 if ((header.xfeatures >> i) & 1) {
1099                         void *src = __raw_xsave_addr(xsave, i);
1100
1101                         offset = xstate_offsets[i];
1102                         size = xstate_sizes[i];
1103
1104                         /* The next component has to fit fully into the output buffer: */
1105                         if (offset + size > size_total)
1106                                 break;
1107
1108                         ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
1109                         if (ret)
1110                                 return ret;
1111                 }
1112
1113         }
1114
1115         if (xfeatures_mxcsr_quirk(header.xfeatures)) {
1116                 offset = offsetof(struct fxregs_state, mxcsr);
1117                 size = MXCSR_AND_FLAGS_SIZE;
1118                 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total);
1119         }
1120
1121         /*
1122          * Fill xsave->i387.sw_reserved value for ptrace frame:
1123          */
1124         offset = offsetof(struct fxregs_state, sw_reserved);
1125         size = sizeof(xstate_fx_sw_bytes);
1126
1127         ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total);
1128         if (ret)
1129                 return ret;
1130
1131         return 0;
1132 }
1133
1134 /*
1135  * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
1136  * and copy to the target thread. This is called from xstateregs_set().
1137  */
1138 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
1139 {
1140         unsigned int offset, size;
1141         int i;
1142         struct xstate_header hdr;
1143
1144         offset = offsetof(struct xregs_state, header);
1145         size = sizeof(hdr);
1146
1147         memcpy(&hdr, kbuf + offset, size);
1148
1149         if (validate_xstate_header(&hdr))
1150                 return -EINVAL;
1151
1152         for (i = 0; i < XFEATURE_MAX; i++) {
1153                 u64 mask = ((u64)1 << i);
1154
1155                 if (hdr.xfeatures & mask) {
1156                         void *dst = __raw_xsave_addr(xsave, i);
1157
1158                         offset = xstate_offsets[i];
1159                         size = xstate_sizes[i];
1160
1161                         memcpy(dst, kbuf + offset, size);
1162                 }
1163         }
1164
1165         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1166                 offset = offsetof(struct fxregs_state, mxcsr);
1167                 size = MXCSR_AND_FLAGS_SIZE;
1168                 memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
1169         }
1170
1171         /*
1172          * The state that came in from userspace was user-state only.
1173          * Mask all the user states out of 'xfeatures':
1174          */
1175         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1176
1177         /*
1178          * Add back in the features that came in from userspace:
1179          */
1180         xsave->header.xfeatures |= hdr.xfeatures;
1181
1182         return 0;
1183 }
1184
1185 /*
1186  * Convert from a ptrace or sigreturn standard-format user-space buffer to
1187  * kernel XSAVES format and copy to the target thread. This is called from
1188  * xstateregs_set(), as well as potentially from the sigreturn() and
1189  * rt_sigreturn() system calls.
1190  */
1191 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
1192 {
1193         unsigned int offset, size;
1194         int i;
1195         struct xstate_header hdr;
1196
1197         offset = offsetof(struct xregs_state, header);
1198         size = sizeof(hdr);
1199
1200         if (__copy_from_user(&hdr, ubuf + offset, size))
1201                 return -EFAULT;
1202
1203         if (validate_xstate_header(&hdr))
1204                 return -EINVAL;
1205
1206         for (i = 0; i < XFEATURE_MAX; i++) {
1207                 u64 mask = ((u64)1 << i);
1208
1209                 if (hdr.xfeatures & mask) {
1210                         void *dst = __raw_xsave_addr(xsave, i);
1211
1212                         offset = xstate_offsets[i];
1213                         size = xstate_sizes[i];
1214
1215                         if (__copy_from_user(dst, ubuf + offset, size))
1216                                 return -EFAULT;
1217                 }
1218         }
1219
1220         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1221                 offset = offsetof(struct fxregs_state, mxcsr);
1222                 size = MXCSR_AND_FLAGS_SIZE;
1223                 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
1224                         return -EFAULT;
1225         }
1226
1227         /*
1228          * The state that came in from userspace was user-state only.
1229          * Mask all the user states out of 'xfeatures':
1230          */
1231         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1232
1233         /*
1234          * Add back in the features that came in from userspace:
1235          */
1236         xsave->header.xfeatures |= hdr.xfeatures;
1237
1238         return 0;
1239 }
1240
1241 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1242 /*
1243  * Report the amount of time elapsed in millisecond since last AVX512
1244  * use in the task.
1245  */
1246 static void avx512_status(struct seq_file *m, struct task_struct *task)
1247 {
1248         unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1249         long delta;
1250
1251         if (!timestamp) {
1252                 /*
1253                  * Report -1 if no AVX512 usage
1254                  */
1255                 delta = -1;
1256         } else {
1257                 delta = (long)(jiffies - timestamp);
1258                 /*
1259                  * Cap to LONG_MAX if time difference > LONG_MAX
1260                  */
1261                 if (delta < 0)
1262                         delta = LONG_MAX;
1263                 delta = jiffies_to_msecs(delta);
1264         }
1265
1266         seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1267         seq_putc(m, '\n');
1268 }
1269
1270 /*
1271  * Report architecture specific information
1272  */
1273 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1274                         struct pid *pid, struct task_struct *task)
1275 {
1276         /*
1277          * Report AVX512 state if the processor and build option supported.
1278          */
1279         if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1280                 avx512_status(m, task);
1281
1282         return 0;
1283 }
1284 #endif /* CONFIG_PROC_PID_ARCH_STATUS */