arch/x86/kernel/fpu/xstate.c

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This source file includes following definitions.
cpu_has_xfeatures
xfeature_is_supervisor
xfeature_is_user
fpstate_sanitize_xstate
fpu__init_cpu_xstate
xfeature_enabled
setup_xstate_features
print_xstate_feature
print_xstate_features
xfeature_is_aligned
setup_xstate_comp
print_xstate_offset_size
setup_init_fpu_buf
xfeature_uncompacted_offset
xfeature_size
using_compacted_format
validate_xstate_header
__xstate_dump_leaves
check_xstate_against_struct
do_extra_xstate_size_checks
get_xsaves_size
get_xsave_size
is_supported_xstate_size
init_xstate_size
fpu__init_disable_system_xstate
fpu__init_system_xstate
fpu__resume_cpu
__raw_xsave_addr
get_xsave_addr
get_xsave_field_ptr
arch_set_user_pkey_access
xfeatures_mxcsr_quirk
fill_gap
copy_part
copy_xstate_to_kernel
__copy_xstate_to_user
copy_xstate_to_user
copy_kernel_to_xstate
copy_user_to_xstate
avx512_status
proc_pid_arch_status
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * xsave/xrstor support.
   4  *
   5  * Author: Suresh Siddha <suresh.b.siddha@intel.com>
   6  */
   7 #include <linux/compat.h>
   8 #include <linux/cpu.h>
   9 #include <linux/mman.h>
  10 #include <linux/pkeys.h>
  11 #include <linux/seq_file.h>
  12 #include <linux/proc_fs.h>
  13 
  14 #include <asm/fpu/api.h>
  15 #include <asm/fpu/internal.h>
  16 #include <asm/fpu/signal.h>
  17 #include <asm/fpu/regset.h>
  18 #include <asm/fpu/xstate.h>
  19 
  20 #include <asm/tlbflush.h>
  21 #include <asm/cpufeature.h>
  22 
  23 /*
  24  * Although we spell it out in here, the Processor Trace
  25  * xfeature is completely unused.  We use other mechanisms
  26  * to save/restore PT state in Linux.
  27  */
  28 static const char *xfeature_names[] =
  29 {
  30         "x87 floating point registers"  ,
  31         "SSE registers"                 ,
  32         "AVX registers"                 ,
  33         "MPX bounds registers"          ,
  34         "MPX CSR"                       ,
  35         "AVX-512 opmask"                ,
  36         "AVX-512 Hi256"                 ,
  37         "AVX-512 ZMM_Hi256"             ,
  38         "Processor Trace (unused)"      ,
  39         "Protection Keys User registers",
  40         "unknown xstate feature"        ,
  41 };
  42 
  43 static short xsave_cpuid_features[] __initdata = {
  44         X86_FEATURE_FPU,
  45         X86_FEATURE_XMM,
  46         X86_FEATURE_AVX,
  47         X86_FEATURE_MPX,
  48         X86_FEATURE_MPX,
  49         X86_FEATURE_AVX512F,
  50         X86_FEATURE_AVX512F,
  51         X86_FEATURE_AVX512F,
  52         X86_FEATURE_INTEL_PT,
  53         X86_FEATURE_PKU,
  54 };
  55 
  56 /*
  57  * Mask of xstate features supported by the CPU and the kernel:
  58  */
  59 u64 xfeatures_mask __read_mostly;
  60 
  61 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
  62 static unsigned int xstate_sizes[XFEATURE_MAX]   = { [ 0 ... XFEATURE_MAX - 1] = -1};
  63 static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
  64 
  65 /*
  66  * The XSAVE area of kernel can be in standard or compacted format;
  67  * it is always in standard format for user mode. This is the user
  68  * mode standard format size used for signal and ptrace frames.
  69  */
  70 unsigned int fpu_user_xstate_size;
  71 
  72 /*
  73  * Return whether the system supports a given xfeature.
  74  *
  75  * Also return the name of the (most advanced) feature that the caller requested:
  76  */
  77 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
  78 {
  79         u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask;
  80 
  81         if (unlikely(feature_name)) {
  82                 long xfeature_idx, max_idx;
  83                 u64 xfeatures_print;
  84                 /*
  85                  * So we use FLS here to be able to print the most advanced
  86                  * feature that was requested but is missing. So if a driver
  87                  * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the
  88                  * missing AVX feature - this is the most informative message
  89                  * to users:
  90                  */
  91                 if (xfeatures_missing)
  92                         xfeatures_print = xfeatures_missing;
  93                 else
  94                         xfeatures_print = xfeatures_needed;
  95 
  96                 xfeature_idx = fls64(xfeatures_print)-1;
  97                 max_idx = ARRAY_SIZE(xfeature_names)-1;
  98                 xfeature_idx = min(xfeature_idx, max_idx);
  99 
 100                 *feature_name = xfeature_names[xfeature_idx];
 101         }
 102 
 103         if (xfeatures_missing)
 104                 return 0;
 105 
 106         return 1;
 107 }
 108 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
 109 
 110 static int xfeature_is_supervisor(int xfeature_nr)
 111 {
 112         /*
 113          * We currently do not support supervisor states, but if
 114          * we did, we could find out like this.
 115          *
 116          * SDM says: If state component 'i' is a user state component,
 117          * ECX[0] return 0; if state component i is a supervisor
 118          * state component, ECX[0] returns 1.
 119          */
 120         u32 eax, ebx, ecx, edx;
 121 
 122         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 123         return !!(ecx & 1);
 124 }
 125 
 126 static int xfeature_is_user(int xfeature_nr)
 127 {
 128         return !xfeature_is_supervisor(xfeature_nr);
 129 }
 130 
 131 /*
 132  * When executing XSAVEOPT (or other optimized XSAVE instructions), if
 133  * a processor implementation detects that an FPU state component is still
 134  * (or is again) in its initialized state, it may clear the corresponding
 135  * bit in the header.xfeatures field, and can skip the writeout of registers
 136  * to the corresponding memory layout.
 137  *
 138  * This means that when the bit is zero, the state component might still contain
 139  * some previous - non-initialized register state.
 140  *
 141  * Before writing xstate information to user-space we sanitize those components,
 142  * to always ensure that the memory layout of a feature will be in the init state
 143  * if the corresponding header bit is zero. This is to ensure that user-space doesn't
 144  * see some stale state in the memory layout during signal handling, debugging etc.
 145  */
 146 void fpstate_sanitize_xstate(struct fpu *fpu)
 147 {
 148         struct fxregs_state *fx = &fpu->state.fxsave;
 149         int feature_bit;
 150         u64 xfeatures;
 151 
 152         if (!use_xsaveopt())
 153                 return;
 154 
 155         xfeatures = fpu->state.xsave.header.xfeatures;
 156 
 157         /*
 158          * None of the feature bits are in init state. So nothing else
 159          * to do for us, as the memory layout is up to date.
 160          */
 161         if ((xfeatures & xfeatures_mask) == xfeatures_mask)
 162                 return;
 163 
 164         /*
 165          * FP is in init state
 166          */
 167         if (!(xfeatures & XFEATURE_MASK_FP)) {
 168                 fx->cwd = 0x37f;
 169                 fx->swd = 0;
 170                 fx->twd = 0;
 171                 fx->fop = 0;
 172                 fx->rip = 0;
 173                 fx->rdp = 0;
 174                 memset(&fx->st_space[0], 0, 128);
 175         }
 176 
 177         /*
 178          * SSE is in init state
 179          */
 180         if (!(xfeatures & XFEATURE_MASK_SSE))
 181                 memset(&fx->xmm_space[0], 0, 256);
 182 
 183         /*
 184          * First two features are FPU and SSE, which above we handled
 185          * in a special way already:
 186          */
 187         feature_bit = 0x2;
 188         xfeatures = (xfeatures_mask & ~xfeatures) >> 2;
 189 
 190         /*
 191          * Update all the remaining memory layouts according to their
 192          * standard xstate layout, if their header bit is in the init
 193          * state:
 194          */
 195         while (xfeatures) {
 196                 if (xfeatures & 0x1) {
 197                         int offset = xstate_comp_offsets[feature_bit];
 198                         int size = xstate_sizes[feature_bit];
 199 
 200                         memcpy((void *)fx + offset,
 201                                (void *)&init_fpstate.xsave + offset,
 202                                size);
 203                 }
 204 
 205                 xfeatures >>= 1;
 206                 feature_bit++;
 207         }
 208 }
 209 
 210 /*
 211  * Enable the extended processor state save/restore feature.
 212  * Called once per CPU onlining.
 213  */
 214 void fpu__init_cpu_xstate(void)
 215 {
 216         if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask)
 217                 return;
 218         /*
 219          * Make it clear that XSAVES supervisor states are not yet
 220          * implemented should anyone expect it to work by changing
 221          * bits in XFEATURE_MASK_* macros and XCR0.
 222          */
 223         WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR),
 224                 "x86/fpu: XSAVES supervisor states are not yet implemented.\n");
 225 
 226         xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR;
 227 
 228         cr4_set_bits(X86_CR4_OSXSAVE);
 229         xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
 230 }
 231 
 232 /*
 233  * Note that in the future we will likely need a pair of
 234  * functions here: one for user xstates and the other for
 235  * system xstates.  For now, they are the same.
 236  */
 237 static int xfeature_enabled(enum xfeature xfeature)
 238 {
 239         return !!(xfeatures_mask & (1UL << xfeature));
 240 }
 241 
 242 /*
 243  * Record the offsets and sizes of various xstates contained
 244  * in the XSAVE state memory layout.
 245  */
 246 static void __init setup_xstate_features(void)
 247 {
 248         u32 eax, ebx, ecx, edx, i;
 249         /* start at the beginnning of the "extended state" */
 250         unsigned int last_good_offset = offsetof(struct xregs_state,
 251                                                  extended_state_area);
 252         /*
 253          * The FP xstates and SSE xstates are legacy states. They are always
 254          * in the fixed offsets in the xsave area in either compacted form
 255          * or standard form.
 256          */
 257         xstate_offsets[0] = 0;
 258         xstate_sizes[0] = offsetof(struct fxregs_state, xmm_space);
 259         xstate_offsets[1] = xstate_sizes[0];
 260         xstate_sizes[1] = FIELD_SIZEOF(struct fxregs_state, xmm_space);
 261 
 262         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 263                 if (!xfeature_enabled(i))
 264                         continue;
 265 
 266                 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 267 
 268                 /*
 269                  * If an xfeature is supervisor state, the offset
 270                  * in EBX is invalid. We leave it to -1.
 271                  */
 272                 if (xfeature_is_user(i))
 273                         xstate_offsets[i] = ebx;
 274 
 275                 xstate_sizes[i] = eax;
 276                 /*
 277                  * In our xstate size checks, we assume that the
 278                  * highest-numbered xstate feature has the
 279                  * highest offset in the buffer.  Ensure it does.
 280                  */
 281                 WARN_ONCE(last_good_offset > xstate_offsets[i],
 282                         "x86/fpu: misordered xstate at %d\n", last_good_offset);
 283                 last_good_offset = xstate_offsets[i];
 284         }
 285 }
 286 
 287 static void __init print_xstate_feature(u64 xstate_mask)
 288 {
 289         const char *feature_name;
 290 
 291         if (cpu_has_xfeatures(xstate_mask, &feature_name))
 292                 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name);
 293 }
 294 
 295 /*
 296  * Print out all the supported xstate features:
 297  */
 298 static void __init print_xstate_features(void)
 299 {
 300         print_xstate_feature(XFEATURE_MASK_FP);
 301         print_xstate_feature(XFEATURE_MASK_SSE);
 302         print_xstate_feature(XFEATURE_MASK_YMM);
 303         print_xstate_feature(XFEATURE_MASK_BNDREGS);
 304         print_xstate_feature(XFEATURE_MASK_BNDCSR);
 305         print_xstate_feature(XFEATURE_MASK_OPMASK);
 306         print_xstate_feature(XFEATURE_MASK_ZMM_Hi256);
 307         print_xstate_feature(XFEATURE_MASK_Hi16_ZMM);
 308         print_xstate_feature(XFEATURE_MASK_PKRU);
 309 }
 310 
 311 /*
 312  * This check is important because it is easy to get XSTATE_*
 313  * confused with XSTATE_BIT_*.
 314  */
 315 #define CHECK_XFEATURE(nr) do {         \
 316         WARN_ON(nr < FIRST_EXTENDED_XFEATURE);  \
 317         WARN_ON(nr >= XFEATURE_MAX);    \
 318 } while (0)
 319 
 320 /*
 321  * We could cache this like xstate_size[], but we only use
 322  * it here, so it would be a waste of space.
 323  */
 324 static int xfeature_is_aligned(int xfeature_nr)
 325 {
 326         u32 eax, ebx, ecx, edx;
 327 
 328         CHECK_XFEATURE(xfeature_nr);
 329         cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
 330         /*
 331          * The value returned by ECX[1] indicates the alignment
 332          * of state component 'i' when the compacted format
 333          * of the extended region of an XSAVE area is used:
 334          */
 335         return !!(ecx & 2);
 336 }
 337 
 338 /*
 339  * This function sets up offsets and sizes of all extended states in
 340  * xsave area. This supports both standard format and compacted format
 341  * of the xsave aread.
 342  */
 343 static void __init setup_xstate_comp(void)
 344 {
 345         unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8];
 346         int i;
 347 
 348         /*
 349          * The FP xstates and SSE xstates are legacy states. They are always
 350          * in the fixed offsets in the xsave area in either compacted form
 351          * or standard form.
 352          */
 353         xstate_comp_offsets[0] = 0;
 354         xstate_comp_offsets[1] = offsetof(struct fxregs_state, xmm_space);
 355 
 356         if (!boot_cpu_has(X86_FEATURE_XSAVES)) {
 357                 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 358                         if (xfeature_enabled(i)) {
 359                                 xstate_comp_offsets[i] = xstate_offsets[i];
 360                                 xstate_comp_sizes[i] = xstate_sizes[i];
 361                         }
 362                 }
 363                 return;
 364         }
 365 
 366         xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] =
 367                 FXSAVE_SIZE + XSAVE_HDR_SIZE;
 368 
 369         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 370                 if (xfeature_enabled(i))
 371                         xstate_comp_sizes[i] = xstate_sizes[i];
 372                 else
 373                         xstate_comp_sizes[i] = 0;
 374 
 375                 if (i > FIRST_EXTENDED_XFEATURE) {
 376                         xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
 377                                         + xstate_comp_sizes[i-1];
 378 
 379                         if (xfeature_is_aligned(i))
 380                                 xstate_comp_offsets[i] =
 381                                         ALIGN(xstate_comp_offsets[i], 64);
 382                 }
 383         }
 384 }
 385 
 386 /*
 387  * Print out xstate component offsets and sizes
 388  */
 389 static void __init print_xstate_offset_size(void)
 390 {
 391         int i;
 392 
 393         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
 394                 if (!xfeature_enabled(i))
 395                         continue;
 396                 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
 397                          i, xstate_comp_offsets[i], i, xstate_sizes[i]);
 398         }
 399 }
 400 
 401 /*
 402  * setup the xstate image representing the init state
 403  */
 404 static void __init setup_init_fpu_buf(void)
 405 {
 406         static int on_boot_cpu __initdata = 1;
 407 
 408         WARN_ON_FPU(!on_boot_cpu);
 409         on_boot_cpu = 0;
 410 
 411         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 412                 return;
 413 
 414         setup_xstate_features();
 415         print_xstate_features();
 416 
 417         if (boot_cpu_has(X86_FEATURE_XSAVES))
 418                 init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | 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 
 432 static 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 
 451 static 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  */
 469 int 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) */
 475 int 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 
 498 static 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  */
 538 static 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  */
 574 static 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  */
 623 static 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 
 638 static 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  */
 656 static 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 
 666 static 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  */
 701 static 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  */
 712 void __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();
 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 
 784 out_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  */
 792 void 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  */
 806 static 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  */
 833 void *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 pcntxt_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 }
 864 EXPORT_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  */
 883 const 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 #define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2)
 899 #define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1)
 900 /*
 901  * This will go out and modify PKRU register to set the access
 902  * rights for @pkey to @init_val.
 903  */
 904 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 905                 unsigned long init_val)
 906 {
 907         u32 old_pkru;
 908         int pkey_shift = (pkey * PKRU_BITS_PER_PKEY);
 909         u32 new_pkru_bits = 0;
 910 
 911         /*
 912          * This check implies XSAVE support.  OSPKE only gets
 913          * set if we enable XSAVE and we enable PKU in XCR0.
 914          */
 915         if (!boot_cpu_has(X86_FEATURE_OSPKE))
 916                 return -EINVAL;
 917 
 918         /* Set the bits we need in PKRU:  */
 919         if (init_val & PKEY_DISABLE_ACCESS)
 920                 new_pkru_bits |= PKRU_AD_BIT;
 921         if (init_val & PKEY_DISABLE_WRITE)
 922                 new_pkru_bits |= PKRU_WD_BIT;
 923 
 924         /* Shift the bits in to the correct place in PKRU for pkey: */
 925         new_pkru_bits <<= pkey_shift;
 926 
 927         /* Get old PKRU and mask off any old bits in place: */
 928         old_pkru = read_pkru();
 929         old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift);
 930 
 931         /* Write old part along with new part: */
 932         write_pkru(old_pkru | new_pkru_bits);
 933 
 934         return 0;
 935 }
 936 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
 937 
 938 /*
 939  * Weird legacy quirk: SSE and YMM states store information in the
 940  * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP
 941  * area is marked as unused in the xfeatures header, we need to copy
 942  * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use.
 943  */
 944 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures)
 945 {
 946         if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM)))
 947                 return false;
 948 
 949         if (xfeatures & XFEATURE_MASK_FP)
 950                 return false;
 951 
 952         return true;
 953 }
 954 
 955 static void fill_gap(unsigned to, void **kbuf, unsigned *pos, unsigned *count)
 956 {
 957         if (*pos < to) {
 958                 unsigned size = to - *pos;
 959 
 960                 if (size > *count)
 961                         size = *count;
 962                 memcpy(*kbuf, (void *)&init_fpstate.xsave + *pos, size);
 963                 *kbuf += size;
 964                 *pos += size;
 965                 *count -= size;
 966         }
 967 }
 968 
 969 static void copy_part(unsigned offset, unsigned size, void *from,
 970                         void **kbuf, unsigned *pos, unsigned *count)
 971 {
 972         fill_gap(offset, kbuf, pos, count);
 973         if (size > *count)
 974                 size = *count;
 975         if (size) {
 976                 memcpy(*kbuf, from, size);
 977                 *kbuf += size;
 978                 *pos += size;
 979                 *count -= size;
 980         }
 981 }
 982 
 983 /*
 984  * Convert from kernel XSAVES compacted format to standard format and copy
 985  * to a kernel-space ptrace buffer.
 986  *
 987  * It supports partial copy but pos always starts from zero. This is called
 988  * from xstateregs_get() and there we check the CPU has XSAVES.
 989  */
 990 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
 991 {
 992         struct xstate_header header;
 993         const unsigned off_mxcsr = offsetof(struct fxregs_state, mxcsr);
 994         unsigned count = size_total;
 995         int i;
 996 
 997         /*
 998          * Currently copy_regset_to_user() starts from pos 0:
 999          */
1000         if (unlikely(offset_start != 0))
1001                 return -EFAULT;
1002 
1003         /*
1004          * The destination is a ptrace buffer; we put in only user xstates:
1005          */
1006         memset(&header, 0, sizeof(header));
1007         header.xfeatures = xsave->header.xfeatures;
1008         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
1009 
1010         if (header.xfeatures & XFEATURE_MASK_FP)
1011                 copy_part(0, off_mxcsr,
1012                           &xsave->i387, &kbuf, &offset_start, &count);
1013         if (header.xfeatures & (XFEATURE_MASK_SSE | XFEATURE_MASK_YMM))
1014                 copy_part(off_mxcsr, MXCSR_AND_FLAGS_SIZE,
1015                           &xsave->i387.mxcsr, &kbuf, &offset_start, &count);
1016         if (header.xfeatures & XFEATURE_MASK_FP)
1017                 copy_part(offsetof(struct fxregs_state, st_space), 128,
1018                           &xsave->i387.st_space, &kbuf, &offset_start, &count);
1019         if (header.xfeatures & XFEATURE_MASK_SSE)
1020                 copy_part(xstate_offsets[XFEATURE_MASK_SSE], 256,
1021                           &xsave->i387.xmm_space, &kbuf, &offset_start, &count);
1022         /*
1023          * Fill xsave->i387.sw_reserved value for ptrace frame:
1024          */
1025         copy_part(offsetof(struct fxregs_state, sw_reserved), 48,
1026                   xstate_fx_sw_bytes, &kbuf, &offset_start, &count);
1027         /*
1028          * Copy xregs_state->header:
1029          */
1030         copy_part(offsetof(struct xregs_state, header), sizeof(header),
1031                   &header, &kbuf, &offset_start, &count);
1032 
1033         for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) {
1034                 /*
1035                  * Copy only in-use xstates:
1036                  */
1037                 if ((header.xfeatures >> i) & 1) {
1038                         void *src = __raw_xsave_addr(xsave, i);
1039 
1040                         copy_part(xstate_offsets[i], xstate_sizes[i],
1041                                   src, &kbuf, &offset_start, &count);
1042                 }
1043 
1044         }
1045         fill_gap(size_total, &kbuf, &offset_start, &count);
1046 
1047         return 0;
1048 }
1049 
1050 static inline int
1051 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total)
1052 {
1053         if (!size)
1054                 return 0;
1055 
1056         if (offset < size_total) {
1057                 unsigned int copy = min(size, size_total - offset);
1058 
1059                 if (__copy_to_user(ubuf + offset, data, copy))
1060                         return -EFAULT;
1061         }
1062         return 0;
1063 }
1064 
1065 /*
1066  * Convert from kernel XSAVES compacted format to standard format and copy
1067  * to a user-space buffer. It supports partial copy but pos always starts from
1068  * zero. This is called from xstateregs_get() and there we check the CPU
1069  * has XSAVES.
1070  */
1071 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total)
1072 {
1073         unsigned int offset, size;
1074         int ret, i;
1075         struct xstate_header header;
1076 
1077         /*
1078          * Currently copy_regset_to_user() starts from pos 0:
1079          */
1080         if (unlikely(offset_start != 0))
1081                 return -EFAULT;
1082 
1083         /*
1084          * The destination is a ptrace buffer; we put in only user xstates:
1085          */
1086         memset(&header, 0, sizeof(header));
1087         header.xfeatures = xsave->header.xfeatures;
1088         header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR;
1089 
1090         /*
1091          * Copy xregs_state->header:
1092          */
1093         offset = offsetof(struct xregs_state, header);
1094         size = sizeof(header);
1095 
1096         ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total);
1097         if (ret)
1098                 return ret;
1099 
1100         for (i = 0; i < XFEATURE_MAX; i++) {
1101                 /*
1102                  * Copy only in-use xstates:
1103                  */
1104                 if ((header.xfeatures >> i) & 1) {
1105                         void *src = __raw_xsave_addr(xsave, i);
1106 
1107                         offset = xstate_offsets[i];
1108                         size = xstate_sizes[i];
1109 
1110                         /* The next component has to fit fully into the output buffer: */
1111                         if (offset + size > size_total)
1112                                 break;
1113 
1114                         ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total);
1115                         if (ret)
1116                                 return ret;
1117                 }
1118 
1119         }
1120 
1121         if (xfeatures_mxcsr_quirk(header.xfeatures)) {
1122                 offset = offsetof(struct fxregs_state, mxcsr);
1123                 size = MXCSR_AND_FLAGS_SIZE;
1124                 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total);
1125         }
1126 
1127         /*
1128          * Fill xsave->i387.sw_reserved value for ptrace frame:
1129          */
1130         offset = offsetof(struct fxregs_state, sw_reserved);
1131         size = sizeof(xstate_fx_sw_bytes);
1132 
1133         ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total);
1134         if (ret)
1135                 return ret;
1136 
1137         return 0;
1138 }
1139 
1140 /*
1141  * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format
1142  * and copy to the target thread. This is called from xstateregs_set().
1143  */
1144 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
1145 {
1146         unsigned int offset, size;
1147         int i;
1148         struct xstate_header hdr;
1149 
1150         offset = offsetof(struct xregs_state, header);
1151         size = sizeof(hdr);
1152 
1153         memcpy(&hdr, kbuf + offset, size);
1154 
1155         if (validate_xstate_header(&hdr))
1156                 return -EINVAL;
1157 
1158         for (i = 0; i < XFEATURE_MAX; i++) {
1159                 u64 mask = ((u64)1 << i);
1160 
1161                 if (hdr.xfeatures & mask) {
1162                         void *dst = __raw_xsave_addr(xsave, i);
1163 
1164                         offset = xstate_offsets[i];
1165                         size = xstate_sizes[i];
1166 
1167                         memcpy(dst, kbuf + offset, size);
1168                 }
1169         }
1170 
1171         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1172                 offset = offsetof(struct fxregs_state, mxcsr);
1173                 size = MXCSR_AND_FLAGS_SIZE;
1174                 memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
1175         }
1176 
1177         /*
1178          * The state that came in from userspace was user-state only.
1179          * Mask all the user states out of 'xfeatures':
1180          */
1181         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1182 
1183         /*
1184          * Add back in the features that came in from userspace:
1185          */
1186         xsave->header.xfeatures |= hdr.xfeatures;
1187 
1188         return 0;
1189 }
1190 
1191 /*
1192  * Convert from a ptrace or sigreturn standard-format user-space buffer to
1193  * kernel XSAVES format and copy to the target thread. This is called from
1194  * xstateregs_set(), as well as potentially from the sigreturn() and
1195  * rt_sigreturn() system calls.
1196  */
1197 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
1198 {
1199         unsigned int offset, size;
1200         int i;
1201         struct xstate_header hdr;
1202 
1203         offset = offsetof(struct xregs_state, header);
1204         size = sizeof(hdr);
1205 
1206         if (__copy_from_user(&hdr, ubuf + offset, size))
1207                 return -EFAULT;
1208 
1209         if (validate_xstate_header(&hdr))
1210                 return -EINVAL;
1211 
1212         for (i = 0; i < XFEATURE_MAX; i++) {
1213                 u64 mask = ((u64)1 << i);
1214 
1215                 if (hdr.xfeatures & mask) {
1216                         void *dst = __raw_xsave_addr(xsave, i);
1217 
1218                         offset = xstate_offsets[i];
1219                         size = xstate_sizes[i];
1220 
1221                         if (__copy_from_user(dst, ubuf + offset, size))
1222                                 return -EFAULT;
1223                 }
1224         }
1225 
1226         if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
1227                 offset = offsetof(struct fxregs_state, mxcsr);
1228                 size = MXCSR_AND_FLAGS_SIZE;
1229                 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size))
1230                         return -EFAULT;
1231         }
1232 
1233         /*
1234          * The state that came in from userspace was user-state only.
1235          * Mask all the user states out of 'xfeatures':
1236          */
1237         xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR;
1238 
1239         /*
1240          * Add back in the features that came in from userspace:
1241          */
1242         xsave->header.xfeatures |= hdr.xfeatures;
1243 
1244         return 0;
1245 }
1246 
1247 #ifdef CONFIG_PROC_PID_ARCH_STATUS
1248 /*
1249  * Report the amount of time elapsed in millisecond since last AVX512
1250  * use in the task.
1251  */
1252 static void avx512_status(struct seq_file *m, struct task_struct *task)
1253 {
1254         unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp);
1255         long delta;
1256 
1257         if (!timestamp) {
1258                 /*
1259                  * Report -1 if no AVX512 usage
1260                  */
1261                 delta = -1;
1262         } else {
1263                 delta = (long)(jiffies - timestamp);
1264                 /*
1265                  * Cap to LONG_MAX if time difference > LONG_MAX
1266                  */
1267                 if (delta < 0)
1268                         delta = LONG_MAX;
1269                 delta = jiffies_to_msecs(delta);
1270         }
1271 
1272         seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta);
1273         seq_putc(m, '\n');
1274 }
1275 
1276 /*
1277  * Report architecture specific information
1278  */
1279 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
1280                         struct pid *pid, struct task_struct *task)
1281 {
1282         /*
1283          * Report AVX512 state if the processor and build option supported.
1284          */
1285         if (cpu_feature_enabled(X86_FEATURE_AVX512F))
1286                 avx512_status(m, task);
1287 
1288         return 0;
1289 }
1290 #endif /* CONFIG_PROC_PID_ARCH_STATUS */
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root/arch/x86/kernel/fpu/xstate.c

DEFINITIONS
