1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * xsave/xrstor support. 4 * 5 * Author: Suresh Siddha <suresh.b.siddha@intel.com> 6 */ 7 #include <linux/compat.h> 8 #include <linux/cpu.h> 9 #include <linux/mman.h> 10 #include <linux/pkeys.h> 11 #include <linux/seq_file.h> 12 #include <linux/proc_fs.h> 13 14 #include <asm/fpu/api.h> 15 #include <asm/fpu/internal.h> 16 #include <asm/fpu/signal.h> 17 #include <asm/fpu/regset.h> 18 #include <asm/fpu/xstate.h> 19 20 #include <asm/tlbflush.h> 21 #include <asm/cpufeature.h> 22 23 /* 24 * Although we spell it out in here, the Processor Trace 25 * xfeature is completely unused. We use other mechanisms 26 * to save/restore PT state in Linux. 27 */ 28 static const char *xfeature_names[] = 29 { 30 "x87 floating point registers" , 31 "SSE registers" , 32 "AVX registers" , 33 "MPX bounds registers" , 34 "MPX CSR" , 35 "AVX-512 opmask" , 36 "AVX-512 Hi256" , 37 "AVX-512 ZMM_Hi256" , 38 "Processor Trace (unused)" , 39 "Protection Keys User registers", 40 "unknown xstate feature" , 41 }; 42 43 static short xsave_cpuid_features[] __initdata = { 44 X86_FEATURE_FPU, 45 X86_FEATURE_XMM, 46 X86_FEATURE_AVX, 47 X86_FEATURE_MPX, 48 X86_FEATURE_MPX, 49 X86_FEATURE_AVX512F, 50 X86_FEATURE_AVX512F, 51 X86_FEATURE_AVX512F, 52 X86_FEATURE_INTEL_PT, 53 X86_FEATURE_PKU, 54 }; 55 56 /* 57 * Mask of xstate features supported by the CPU and the kernel: 58 */ 59 u64 xfeatures_mask __read_mostly; 60 61 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 62 static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 63 static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 64 65 /* 66 * The XSAVE area of kernel can be in standard or compacted format; 67 * it is always in standard format for user mode. This is the user 68 * mode standard format size used for signal and ptrace frames. 69 */ 70 unsigned int fpu_user_xstate_size; 71 72 /* 73 * Return whether the system supports a given xfeature. 74 * 75 * Also return the name of the (most advanced) feature that the caller requested: 76 */ 77 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) 78 { 79 u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask; 80 81 if (unlikely(feature_name)) { 82 long xfeature_idx, max_idx; 83 u64 xfeatures_print; 84 /* 85 * So we use FLS here to be able to print the most advanced 86 * feature that was requested but is missing. So if a driver 87 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the 88 * missing AVX feature - this is the most informative message 89 * to users: 90 */ 91 if (xfeatures_missing) 92 xfeatures_print = xfeatures_missing; 93 else 94 xfeatures_print = xfeatures_needed; 95 96 xfeature_idx = fls64(xfeatures_print)-1; 97 max_idx = ARRAY_SIZE(xfeature_names)-1; 98 xfeature_idx = min(xfeature_idx, max_idx); 99 100 *feature_name = xfeature_names[xfeature_idx]; 101 } 102 103 if (xfeatures_missing) 104 return 0; 105 106 return 1; 107 } 108 EXPORT_SYMBOL_GPL(cpu_has_xfeatures); 109 110 static 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 */ 138 void 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 */ 206 void 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 */ 229 static 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 */ 238 static 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 } 285 286 static 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 */ 297 static 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 */ 323 static 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 */ 349 static 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 */ 388 static 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 */ 403 static 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 } 431 432 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_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; 783 784 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 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 } 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 = ¤t->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 */ 902 int 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 */ 949 static 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 } 959 960 /* 961 * This is similar to user_regset_copyout(), but will not add offset to 962 * the source data pointer or increment pos, count, kbuf, and ubuf. 963 */ 964 static inline void 965 __copy_xstate_to_kernel(void *kbuf, const void *data, 966 unsigned int offset, unsigned int size, unsigned int size_total) 967 { 968 if (offset < size_total) { 969 unsigned int copy = min(size, size_total - offset); 970 971 memcpy(kbuf + offset, data, copy); 972 } 973 } 974 975 /* 976 * Convert from kernel XSAVES compacted format to standard format and copy 977 * to a kernel-space ptrace buffer. 978 * 979 * It supports partial copy but pos always starts from zero. This is called 980 * from xstateregs_get() and there we check the CPU has XSAVES. 981 */ 982 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 983 { 984 unsigned int offset, size; 985 struct xstate_header header; 986 int i; 987 988 /* 989 * Currently copy_regset_to_user() starts from pos 0: 990 */ 991 if (unlikely(offset_start != 0)) 992 return -EFAULT; 993 994 /* 995 * The destination is a ptrace buffer; we put in only user xstates: 996 */ 997 memset(&header, 0, sizeof(header)); 998 header.xfeatures = xsave->header.xfeatures; 999 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1000 1001 /* 1002 * Copy xregs_state->header: 1003 */ 1004 offset = offsetof(struct xregs_state, header); 1005 size = sizeof(header); 1006 1007 __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total); 1008 1009 for (i = 0; i < XFEATURE_MAX; i++) { 1010 /* 1011 * Copy only in-use xstates: 1012 */ 1013 if ((header.xfeatures >> i) & 1) { 1014 void *src = __raw_xsave_addr(xsave, i); 1015 1016 offset = xstate_offsets[i]; 1017 size = xstate_sizes[i]; 1018 1019 /* The next component has to fit fully into the output buffer: */ 1020 if (offset + size > size_total) 1021 break; 1022 1023 __copy_xstate_to_kernel(kbuf, src, offset, size, size_total); 1024 } 1025 1026 } 1027 1028 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1029 offset = offsetof(struct fxregs_state, mxcsr); 1030 size = MXCSR_AND_FLAGS_SIZE; 1031 __copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total); 1032 } 1033 1034 /* 1035 * Fill xsave->i387.sw_reserved value for ptrace frame: 1036 */ 1037 offset = offsetof(struct fxregs_state, sw_reserved); 1038 size = sizeof(xstate_fx_sw_bytes); 1039 1040 __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total); 1041 1042 return 0; 1043 } 1044 1045 static inline int 1046 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total) 1047 { 1048 if (!size) 1049 return 0; 1050 1051 if (offset < size_total) { 1052 unsigned int copy = min(size, size_total - offset); 1053 1054 if (__copy_to_user(ubuf + offset, data, copy)) 1055 return -EFAULT; 1056 } 1057 return 0; 1058 } 1059 1060 /* 1061 * Convert from kernel XSAVES compacted format to standard format and copy 1062 * to a user-space buffer. It supports partial copy but pos always starts from 1063 * zero. This is called from xstateregs_get() and there we check the CPU 1064 * has XSAVES. 1065 */ 1066 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 1067 { 1068 unsigned int offset, size; 1069 int ret, i; 1070 struct xstate_header header; 1071 1072 /* 1073 * Currently copy_regset_to_user() starts from pos 0: 1074 */ 1075 if (unlikely(offset_start != 0)) 1076 return -EFAULT; 1077 1078 /* 1079 * The destination is a ptrace buffer; we put in only user xstates: 1080 */ 1081 memset(&header, 0, sizeof(header)); 1082 header.xfeatures = xsave->header.xfeatures; 1083 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1084 1085 /* 1086 * Copy xregs_state->header: 1087 */ 1088 offset = offsetof(struct xregs_state, header); 1089 size = sizeof(header); 1090 1091 ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total); 1092 if (ret) 1093 return ret; 1094 1095 for (i = 0; i < XFEATURE_MAX; i++) { 1096 /* 1097 * Copy only in-use xstates: 1098 */ 1099 if ((header.xfeatures >> i) & 1) { 1100 void *src = __raw_xsave_addr(xsave, i); 1101 1102 offset = xstate_offsets[i]; 1103 size = xstate_sizes[i]; 1104 1105 /* The next component has to fit fully into the output buffer: */ 1106 if (offset + size > size_total) 1107 break; 1108 1109 ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total); 1110 if (ret) 1111 return ret; 1112 } 1113 1114 } 1115 1116 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1117 offset = offsetof(struct fxregs_state, mxcsr); 1118 size = MXCSR_AND_FLAGS_SIZE; 1119 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total); 1120 } 1121 1122 /* 1123 * Fill xsave->i387.sw_reserved value for ptrace frame: 1124 */ 1125 offset = offsetof(struct fxregs_state, sw_reserved); 1126 size = sizeof(xstate_fx_sw_bytes); 1127 1128 ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total); 1129 if (ret) 1130 return ret; 1131 1132 return 0; 1133 } 1134 1135 /* 1136 * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format 1137 * and copy to the target thread. This is called from xstateregs_set(). 1138 */ 1139 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) 1140 { 1141 unsigned int offset, size; 1142 int i; 1143 struct xstate_header hdr; 1144 1145 offset = offsetof(struct xregs_state, header); 1146 size = sizeof(hdr); 1147 1148 memcpy(&hdr, kbuf + offset, size); 1149 1150 if (validate_xstate_header(&hdr)) 1151 return -EINVAL; 1152 1153 for (i = 0; i < XFEATURE_MAX; i++) { 1154 u64 mask = ((u64)1 << i); 1155 1156 if (hdr.xfeatures & mask) { 1157 void *dst = __raw_xsave_addr(xsave, i); 1158 1159 offset = xstate_offsets[i]; 1160 size = xstate_sizes[i]; 1161 1162 memcpy(dst, kbuf + offset, size); 1163 } 1164 } 1165 1166 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1167 offset = offsetof(struct fxregs_state, mxcsr); 1168 size = MXCSR_AND_FLAGS_SIZE; 1169 memcpy(&xsave->i387.mxcsr, kbuf + offset, size); 1170 } 1171 1172 /* 1173 * The state that came in from userspace was user-state only. 1174 * Mask all the user states out of 'xfeatures': 1175 */ 1176 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1177 1178 /* 1179 * Add back in the features that came in from userspace: 1180 */ 1181 xsave->header.xfeatures |= hdr.xfeatures; 1182 1183 return 0; 1184 } 1185 1186 /* 1187 * Convert from a ptrace or sigreturn standard-format user-space buffer to 1188 * kernel XSAVES format and copy to the target thread. This is called from 1189 * xstateregs_set(), as well as potentially from the sigreturn() and 1190 * rt_sigreturn() system calls. 1191 */ 1192 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) 1193 { 1194 unsigned int offset, size; 1195 int i; 1196 struct xstate_header hdr; 1197 1198 offset = offsetof(struct xregs_state, header); 1199 size = sizeof(hdr); 1200 1201 if (__copy_from_user(&hdr, ubuf + offset, size)) 1202 return -EFAULT; 1203 1204 if (validate_xstate_header(&hdr)) 1205 return -EINVAL; 1206 1207 for (i = 0; i < XFEATURE_MAX; i++) { 1208 u64 mask = ((u64)1 << i); 1209 1210 if (hdr.xfeatures & mask) { 1211 void *dst = __raw_xsave_addr(xsave, i); 1212 1213 offset = xstate_offsets[i]; 1214 size = xstate_sizes[i]; 1215 1216 if (__copy_from_user(dst, ubuf + offset, size)) 1217 return -EFAULT; 1218 } 1219 } 1220 1221 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1222 offset = offsetof(struct fxregs_state, mxcsr); 1223 size = MXCSR_AND_FLAGS_SIZE; 1224 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size)) 1225 return -EFAULT; 1226 } 1227 1228 /* 1229 * The state that came in from userspace was user-state only. 1230 * Mask all the user states out of 'xfeatures': 1231 */ 1232 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1233 1234 /* 1235 * Add back in the features that came in from userspace: 1236 */ 1237 xsave->header.xfeatures |= hdr.xfeatures; 1238 1239 return 0; 1240 } 1241 1242 #ifdef CONFIG_PROC_PID_ARCH_STATUS 1243 /* 1244 * Report the amount of time elapsed in millisecond since last AVX512 1245 * use in the task. 1246 */ 1247 static void avx512_status(struct seq_file *m, struct task_struct *task) 1248 { 1249 unsigned long timestamp = READ_ONCE(task->thread.fpu.avx512_timestamp); 1250 long delta; 1251 1252 if (!timestamp) { 1253 /* 1254 * Report -1 if no AVX512 usage 1255 */ 1256 delta = -1; 1257 } else { 1258 delta = (long)(jiffies - timestamp); 1259 /* 1260 * Cap to LONG_MAX if time difference > LONG_MAX 1261 */ 1262 if (delta < 0) 1263 delta = LONG_MAX; 1264 delta = jiffies_to_msecs(delta); 1265 } 1266 1267 seq_put_decimal_ll(m, "AVX512_elapsed_ms:\t", delta); 1268 seq_putc(m, '\n'); 1269 } 1270 1271 /* 1272 * Report architecture specific information 1273 */ 1274 int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns, 1275 struct pid *pid, struct task_struct *task) 1276 { 1277 /* 1278 * Report AVX512 state if the processor and build option supported. 1279 */ 1280 if (cpu_feature_enabled(X86_FEATURE_AVX512F)) 1281 avx512_status(m, task); 1282 1283 return 0; 1284 } 1285 #endif /* CONFIG_PROC_PID_ARCH_STATUS */ 1286