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