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 12 #include <asm/fpu/api.h> 13 #include <asm/fpu/internal.h> 14 #include <asm/fpu/signal.h> 15 #include <asm/fpu/regset.h> 16 #include <asm/fpu/xstate.h> 17 18 #include <asm/tlbflush.h> 19 #include <asm/cpufeature.h> 20 21 /* 22 * Although we spell it out in here, the Processor Trace 23 * xfeature is completely unused. We use other mechanisms 24 * to save/restore PT state in Linux. 25 */ 26 static const char *xfeature_names[] = 27 { 28 "x87 floating point registers" , 29 "SSE registers" , 30 "AVX registers" , 31 "MPX bounds registers" , 32 "MPX CSR" , 33 "AVX-512 opmask" , 34 "AVX-512 Hi256" , 35 "AVX-512 ZMM_Hi256" , 36 "Processor Trace (unused)" , 37 "Protection Keys User registers", 38 "unknown xstate feature" , 39 }; 40 41 static short xsave_cpuid_features[] __initdata = { 42 X86_FEATURE_FPU, 43 X86_FEATURE_XMM, 44 X86_FEATURE_AVX, 45 X86_FEATURE_MPX, 46 X86_FEATURE_MPX, 47 X86_FEATURE_AVX512F, 48 X86_FEATURE_AVX512F, 49 X86_FEATURE_AVX512F, 50 X86_FEATURE_INTEL_PT, 51 X86_FEATURE_PKU, 52 }; 53 54 /* 55 * Mask of xstate features supported by the CPU and the kernel: 56 */ 57 u64 xfeatures_mask __read_mostly; 58 59 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 60 static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 61 static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; 62 63 /* 64 * The XSAVE area of kernel can be in standard or compacted format; 65 * it is always in standard format for user mode. This is the user 66 * mode standard format size used for signal and ptrace frames. 67 */ 68 unsigned int fpu_user_xstate_size; 69 70 /* 71 * Clear all of the X86_FEATURE_* bits that are unavailable 72 * when the CPU has no XSAVE support. 73 */ 74 void fpu__xstate_clear_all_cpu_caps(void) 75 { 76 setup_clear_cpu_cap(X86_FEATURE_XSAVE); 77 } 78 79 /* 80 * Return whether the system supports a given xfeature. 81 * 82 * Also return the name of the (most advanced) feature that the caller requested: 83 */ 84 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) 85 { 86 u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask; 87 88 if (unlikely(feature_name)) { 89 long xfeature_idx, max_idx; 90 u64 xfeatures_print; 91 /* 92 * So we use FLS here to be able to print the most advanced 93 * feature that was requested but is missing. So if a driver 94 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the 95 * missing AVX feature - this is the most informative message 96 * to users: 97 */ 98 if (xfeatures_missing) 99 xfeatures_print = xfeatures_missing; 100 else 101 xfeatures_print = xfeatures_needed; 102 103 xfeature_idx = fls64(xfeatures_print)-1; 104 max_idx = ARRAY_SIZE(xfeature_names)-1; 105 xfeature_idx = min(xfeature_idx, max_idx); 106 107 *feature_name = xfeature_names[xfeature_idx]; 108 } 109 110 if (xfeatures_missing) 111 return 0; 112 113 return 1; 114 } 115 EXPORT_SYMBOL_GPL(cpu_has_xfeatures); 116 117 static int xfeature_is_supervisor(int xfeature_nr) 118 { 119 /* 120 * We currently do not support supervisor states, but if 121 * we did, we could find out like this. 122 * 123 * SDM says: If state component 'i' is a user state component, 124 * ECX[0] return 0; if state component i is a supervisor 125 * state component, ECX[0] returns 1. 126 */ 127 u32 eax, ebx, ecx, edx; 128 129 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 130 return !!(ecx & 1); 131 } 132 133 static int xfeature_is_user(int xfeature_nr) 134 { 135 return !xfeature_is_supervisor(xfeature_nr); 136 } 137 138 /* 139 * When executing XSAVEOPT (or other optimized XSAVE instructions), if 140 * a processor implementation detects that an FPU state component is still 141 * (or is again) in its initialized state, it may clear the corresponding 142 * bit in the header.xfeatures field, and can skip the writeout of registers 143 * to the corresponding memory layout. 144 * 145 * This means that when the bit is zero, the state component might still contain 146 * some previous - non-initialized register state. 147 * 148 * Before writing xstate information to user-space we sanitize those components, 149 * to always ensure that the memory layout of a feature will be in the init state 150 * if the corresponding header bit is zero. This is to ensure that user-space doesn't 151 * see some stale state in the memory layout during signal handling, debugging etc. 152 */ 153 void fpstate_sanitize_xstate(struct fpu *fpu) 154 { 155 struct fxregs_state *fx = &fpu->state.fxsave; 156 int feature_bit; 157 u64 xfeatures; 158 159 if (!use_xsaveopt()) 160 return; 161 162 xfeatures = fpu->state.xsave.header.xfeatures; 163 164 /* 165 * None of the feature bits are in init state. So nothing else 166 * to do for us, as the memory layout is up to date. 167 */ 168 if ((xfeatures & xfeatures_mask) == xfeatures_mask) 169 return; 170 171 /* 172 * FP is in init state 173 */ 174 if (!(xfeatures & XFEATURE_MASK_FP)) { 175 fx->cwd = 0x37f; 176 fx->swd = 0; 177 fx->twd = 0; 178 fx->fop = 0; 179 fx->rip = 0; 180 fx->rdp = 0; 181 memset(&fx->st_space[0], 0, 128); 182 } 183 184 /* 185 * SSE is in init state 186 */ 187 if (!(xfeatures & XFEATURE_MASK_SSE)) 188 memset(&fx->xmm_space[0], 0, 256); 189 190 /* 191 * First two features are FPU and SSE, which above we handled 192 * in a special way already: 193 */ 194 feature_bit = 0x2; 195 xfeatures = (xfeatures_mask & ~xfeatures) >> 2; 196 197 /* 198 * Update all the remaining memory layouts according to their 199 * standard xstate layout, if their header bit is in the init 200 * state: 201 */ 202 while (xfeatures) { 203 if (xfeatures & 0x1) { 204 int offset = xstate_comp_offsets[feature_bit]; 205 int size = xstate_sizes[feature_bit]; 206 207 memcpy((void *)fx + offset, 208 (void *)&init_fpstate.xsave + offset, 209 size); 210 } 211 212 xfeatures >>= 1; 213 feature_bit++; 214 } 215 } 216 217 /* 218 * Enable the extended processor state save/restore feature. 219 * Called once per CPU onlining. 220 */ 221 void fpu__init_cpu_xstate(void) 222 { 223 if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) 224 return; 225 /* 226 * Make it clear that XSAVES supervisor states are not yet 227 * implemented should anyone expect it to work by changing 228 * bits in XFEATURE_MASK_* macros and XCR0. 229 */ 230 WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), 231 "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); 232 233 xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; 234 235 cr4_set_bits(X86_CR4_OSXSAVE); 236 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 237 } 238 239 /* 240 * Note that in the future we will likely need a pair of 241 * functions here: one for user xstates and the other for 242 * system xstates. For now, they are the same. 243 */ 244 static int xfeature_enabled(enum xfeature xfeature) 245 { 246 return !!(xfeatures_mask & (1UL << xfeature)); 247 } 248 249 /* 250 * Record the offsets and sizes of various xstates contained 251 * in the XSAVE state memory layout. 252 */ 253 static void __init setup_xstate_features(void) 254 { 255 u32 eax, ebx, ecx, edx, i; 256 /* start at the beginnning of the "extended state" */ 257 unsigned int last_good_offset = offsetof(struct xregs_state, 258 extended_state_area); 259 /* 260 * The FP xstates and SSE xstates are legacy states. They are always 261 * in the fixed offsets in the xsave area in either compacted form 262 * or standard form. 263 */ 264 xstate_offsets[0] = 0; 265 xstate_sizes[0] = offsetof(struct fxregs_state, xmm_space); 266 xstate_offsets[1] = xstate_sizes[0]; 267 xstate_sizes[1] = FIELD_SIZEOF(struct fxregs_state, xmm_space); 268 269 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 270 if (!xfeature_enabled(i)) 271 continue; 272 273 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); 274 275 /* 276 * If an xfeature is supervisor state, the offset 277 * in EBX is invalid. We leave it to -1. 278 */ 279 if (xfeature_is_user(i)) 280 xstate_offsets[i] = ebx; 281 282 xstate_sizes[i] = eax; 283 /* 284 * In our xstate size checks, we assume that the 285 * highest-numbered xstate feature has the 286 * highest offset in the buffer. Ensure it does. 287 */ 288 WARN_ONCE(last_good_offset > xstate_offsets[i], 289 "x86/fpu: misordered xstate at %d\n", last_good_offset); 290 last_good_offset = xstate_offsets[i]; 291 } 292 } 293 294 static void __init print_xstate_feature(u64 xstate_mask) 295 { 296 const char *feature_name; 297 298 if (cpu_has_xfeatures(xstate_mask, &feature_name)) 299 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name); 300 } 301 302 /* 303 * Print out all the supported xstate features: 304 */ 305 static void __init print_xstate_features(void) 306 { 307 print_xstate_feature(XFEATURE_MASK_FP); 308 print_xstate_feature(XFEATURE_MASK_SSE); 309 print_xstate_feature(XFEATURE_MASK_YMM); 310 print_xstate_feature(XFEATURE_MASK_BNDREGS); 311 print_xstate_feature(XFEATURE_MASK_BNDCSR); 312 print_xstate_feature(XFEATURE_MASK_OPMASK); 313 print_xstate_feature(XFEATURE_MASK_ZMM_Hi256); 314 print_xstate_feature(XFEATURE_MASK_Hi16_ZMM); 315 print_xstate_feature(XFEATURE_MASK_PKRU); 316 } 317 318 /* 319 * This check is important because it is easy to get XSTATE_* 320 * confused with XSTATE_BIT_*. 321 */ 322 #define CHECK_XFEATURE(nr) do { \ 323 WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \ 324 WARN_ON(nr >= XFEATURE_MAX); \ 325 } while (0) 326 327 /* 328 * We could cache this like xstate_size[], but we only use 329 * it here, so it would be a waste of space. 330 */ 331 static int xfeature_is_aligned(int xfeature_nr) 332 { 333 u32 eax, ebx, ecx, edx; 334 335 CHECK_XFEATURE(xfeature_nr); 336 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 337 /* 338 * The value returned by ECX[1] indicates the alignment 339 * of state component 'i' when the compacted format 340 * of the extended region of an XSAVE area is used: 341 */ 342 return !!(ecx & 2); 343 } 344 345 /* 346 * This function sets up offsets and sizes of all extended states in 347 * xsave area. This supports both standard format and compacted format 348 * of the xsave aread. 349 */ 350 static void __init setup_xstate_comp(void) 351 { 352 unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8]; 353 int i; 354 355 /* 356 * The FP xstates and SSE xstates are legacy states. They are always 357 * in the fixed offsets in the xsave area in either compacted form 358 * or standard form. 359 */ 360 xstate_comp_offsets[0] = 0; 361 xstate_comp_offsets[1] = offsetof(struct fxregs_state, 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 xstate_comp_sizes[i] = xstate_sizes[i]; 368 } 369 } 370 return; 371 } 372 373 xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] = 374 FXSAVE_SIZE + XSAVE_HDR_SIZE; 375 376 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 377 if (xfeature_enabled(i)) 378 xstate_comp_sizes[i] = xstate_sizes[i]; 379 else 380 xstate_comp_sizes[i] = 0; 381 382 if (i > FIRST_EXTENDED_XFEATURE) { 383 xstate_comp_offsets[i] = xstate_comp_offsets[i-1] 384 + xstate_comp_sizes[i-1]; 385 386 if (xfeature_is_aligned(i)) 387 xstate_comp_offsets[i] = 388 ALIGN(xstate_comp_offsets[i], 64); 389 } 390 } 391 } 392 393 /* 394 * Print out xstate component offsets and sizes 395 */ 396 static void __init print_xstate_offset_size(void) 397 { 398 int i; 399 400 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 401 if (!xfeature_enabled(i)) 402 continue; 403 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n", 404 i, xstate_comp_offsets[i], i, xstate_sizes[i]); 405 } 406 } 407 408 /* 409 * setup the xstate image representing the init state 410 */ 411 static void __init setup_init_fpu_buf(void) 412 { 413 static int on_boot_cpu __initdata = 1; 414 415 WARN_ON_FPU(!on_boot_cpu); 416 on_boot_cpu = 0; 417 418 if (!boot_cpu_has(X86_FEATURE_XSAVE)) 419 return; 420 421 setup_xstate_features(); 422 print_xstate_features(); 423 424 if (boot_cpu_has(X86_FEATURE_XSAVES)) 425 init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; 426 427 /* 428 * Init all the features state with header.xfeatures being 0x0 429 */ 430 copy_kernel_to_xregs_booting(&init_fpstate.xsave); 431 432 /* 433 * Dump the init state again. This is to identify the init state 434 * of any feature which is not represented by all zero's. 435 */ 436 copy_xregs_to_kernel_booting(&init_fpstate.xsave); 437 } 438 439 static int xfeature_uncompacted_offset(int xfeature_nr) 440 { 441 u32 eax, ebx, ecx, edx; 442 443 /* 444 * Only XSAVES supports supervisor states and it uses compacted 445 * format. Checking a supervisor state's uncompacted offset is 446 * an error. 447 */ 448 if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) { 449 WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); 450 return -1; 451 } 452 453 CHECK_XFEATURE(xfeature_nr); 454 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 455 return ebx; 456 } 457 458 static int xfeature_size(int xfeature_nr) 459 { 460 u32 eax, ebx, ecx, edx; 461 462 CHECK_XFEATURE(xfeature_nr); 463 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 464 return eax; 465 } 466 467 /* 468 * 'XSAVES' implies two different things: 469 * 1. saving of supervisor/system state 470 * 2. using the compacted format 471 * 472 * Use this function when dealing with the compacted format so 473 * that it is obvious which aspect of 'XSAVES' is being handled 474 * by the calling code. 475 */ 476 int using_compacted_format(void) 477 { 478 return boot_cpu_has(X86_FEATURE_XSAVES); 479 } 480 481 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ 482 int validate_xstate_header(const struct xstate_header *hdr) 483 { 484 /* No unknown or supervisor features may be set */ 485 if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR)) 486 return -EINVAL; 487 488 /* Userspace must use the uncompacted format */ 489 if (hdr->xcomp_bv) 490 return -EINVAL; 491 492 /* 493 * If 'reserved' is shrunken to add a new field, make sure to validate 494 * that new field here! 495 */ 496 BUILD_BUG_ON(sizeof(hdr->reserved) != 48); 497 498 /* No reserved bits may be set */ 499 if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved))) 500 return -EINVAL; 501 502 return 0; 503 } 504 505 static void __xstate_dump_leaves(void) 506 { 507 int i; 508 u32 eax, ebx, ecx, edx; 509 static int should_dump = 1; 510 511 if (!should_dump) 512 return; 513 should_dump = 0; 514 /* 515 * Dump out a few leaves past the ones that we support 516 * just in case there are some goodies up there 517 */ 518 for (i = 0; i < XFEATURE_MAX + 10; i++) { 519 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); 520 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n", 521 XSTATE_CPUID, i, eax, ebx, ecx, edx); 522 } 523 } 524 525 #define XSTATE_WARN_ON(x) do { \ 526 if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) { \ 527 __xstate_dump_leaves(); \ 528 } \ 529 } while (0) 530 531 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \ 532 if ((nr == nr_macro) && \ 533 WARN_ONCE(sz != sizeof(__struct), \ 534 "%s: struct is %zu bytes, cpu state %d bytes\n", \ 535 __stringify(nr_macro), sizeof(__struct), sz)) { \ 536 __xstate_dump_leaves(); \ 537 } \ 538 } while (0) 539 540 /* 541 * We have a C struct for each 'xstate'. We need to ensure 542 * that our software representation matches what the CPU 543 * tells us about the state's size. 544 */ 545 static void check_xstate_against_struct(int nr) 546 { 547 /* 548 * Ask the CPU for the size of the state. 549 */ 550 int sz = xfeature_size(nr); 551 /* 552 * Match each CPU state with the corresponding software 553 * structure. 554 */ 555 XCHECK_SZ(sz, nr, XFEATURE_YMM, struct ymmh_struct); 556 XCHECK_SZ(sz, nr, XFEATURE_BNDREGS, struct mpx_bndreg_state); 557 XCHECK_SZ(sz, nr, XFEATURE_BNDCSR, struct mpx_bndcsr_state); 558 XCHECK_SZ(sz, nr, XFEATURE_OPMASK, struct avx_512_opmask_state); 559 XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state); 560 XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state); 561 XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state); 562 563 /* 564 * Make *SURE* to add any feature numbers in below if 565 * there are "holes" in the xsave state component 566 * numbers. 567 */ 568 if ((nr < XFEATURE_YMM) || 569 (nr >= XFEATURE_MAX) || 570 (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) { 571 WARN_ONCE(1, "no structure for xstate: %d\n", nr); 572 XSTATE_WARN_ON(1); 573 } 574 } 575 576 /* 577 * This essentially double-checks what the cpu told us about 578 * how large the XSAVE buffer needs to be. We are recalculating 579 * it to be safe. 580 */ 581 static void do_extra_xstate_size_checks(void) 582 { 583 int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; 584 int i; 585 586 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 587 if (!xfeature_enabled(i)) 588 continue; 589 590 check_xstate_against_struct(i); 591 /* 592 * Supervisor state components can be managed only by 593 * XSAVES, which is compacted-format only. 594 */ 595 if (!using_compacted_format()) 596 XSTATE_WARN_ON(xfeature_is_supervisor(i)); 597 598 /* Align from the end of the previous feature */ 599 if (xfeature_is_aligned(i)) 600 paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64); 601 /* 602 * The offset of a given state in the non-compacted 603 * format is given to us in a CPUID leaf. We check 604 * them for being ordered (increasing offsets) in 605 * setup_xstate_features(). 606 */ 607 if (!using_compacted_format()) 608 paranoid_xstate_size = xfeature_uncompacted_offset(i); 609 /* 610 * The compacted-format offset always depends on where 611 * the previous state ended. 612 */ 613 paranoid_xstate_size += xfeature_size(i); 614 } 615 XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size); 616 } 617 618 619 /* 620 * Get total size of enabled xstates in XCR0/xfeatures_mask. 621 * 622 * Note the SDM's wording here. "sub-function 0" only enumerates 623 * the size of the *user* states. If we use it to size a buffer 624 * that we use 'XSAVES' on, we could potentially overflow the 625 * buffer because 'XSAVES' saves system states too. 626 * 627 * Note that we do not currently set any bits on IA32_XSS so 628 * 'XCR0 | IA32_XSS == XCR0' for now. 629 */ 630 static unsigned int __init get_xsaves_size(void) 631 { 632 unsigned int eax, ebx, ecx, edx; 633 /* 634 * - CPUID function 0DH, sub-function 1: 635 * EBX enumerates the size (in bytes) required by 636 * the XSAVES instruction for an XSAVE area 637 * containing all the state components 638 * corresponding to bits currently set in 639 * XCR0 | IA32_XSS. 640 */ 641 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx); 642 return ebx; 643 } 644 645 static unsigned int __init get_xsave_size(void) 646 { 647 unsigned int eax, ebx, ecx, edx; 648 /* 649 * - CPUID function 0DH, sub-function 0: 650 * EBX enumerates the size (in bytes) required by 651 * the XSAVE instruction for an XSAVE area 652 * containing all the *user* state components 653 * corresponding to bits currently set in XCR0. 654 */ 655 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 656 return ebx; 657 } 658 659 /* 660 * Will the runtime-enumerated 'xstate_size' fit in the init 661 * task's statically-allocated buffer? 662 */ 663 static bool is_supported_xstate_size(unsigned int test_xstate_size) 664 { 665 if (test_xstate_size <= sizeof(union fpregs_state)) 666 return true; 667 668 pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n", 669 sizeof(union fpregs_state), test_xstate_size); 670 return false; 671 } 672 673 static int __init init_xstate_size(void) 674 { 675 /* Recompute the context size for enabled features: */ 676 unsigned int possible_xstate_size; 677 unsigned int xsave_size; 678 679 xsave_size = get_xsave_size(); 680 681 if (boot_cpu_has(X86_FEATURE_XSAVES)) 682 possible_xstate_size = get_xsaves_size(); 683 else 684 possible_xstate_size = xsave_size; 685 686 /* Ensure we have the space to store all enabled: */ 687 if (!is_supported_xstate_size(possible_xstate_size)) 688 return -EINVAL; 689 690 /* 691 * The size is OK, we are definitely going to use xsave, 692 * make it known to the world that we need more space. 693 */ 694 fpu_kernel_xstate_size = possible_xstate_size; 695 do_extra_xstate_size_checks(); 696 697 /* 698 * User space is always in standard format. 699 */ 700 fpu_user_xstate_size = xsave_size; 701 return 0; 702 } 703 704 /* 705 * We enabled the XSAVE hardware, but something went wrong and 706 * we can not use it. Disable it. 707 */ 708 static void fpu__init_disable_system_xstate(void) 709 { 710 xfeatures_mask = 0; 711 cr4_clear_bits(X86_CR4_OSXSAVE); 712 fpu__xstate_clear_all_cpu_caps(); 713 } 714 715 /* 716 * Enable and initialize the xsave feature. 717 * Called once per system bootup. 718 */ 719 void __init fpu__init_system_xstate(void) 720 { 721 unsigned int eax, ebx, ecx, edx; 722 static int on_boot_cpu __initdata = 1; 723 int err; 724 int i; 725 726 WARN_ON_FPU(!on_boot_cpu); 727 on_boot_cpu = 0; 728 729 if (!boot_cpu_has(X86_FEATURE_FPU)) { 730 pr_info("x86/fpu: No FPU detected\n"); 731 return; 732 } 733 734 if (!boot_cpu_has(X86_FEATURE_XSAVE)) { 735 pr_info("x86/fpu: x87 FPU will use %s\n", 736 boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE"); 737 return; 738 } 739 740 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { 741 WARN_ON_FPU(1); 742 return; 743 } 744 745 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 746 xfeatures_mask = eax + ((u64)edx << 32); 747 748 if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) { 749 /* 750 * This indicates that something really unexpected happened 751 * with the enumeration. Disable XSAVE and try to continue 752 * booting without it. This is too early to BUG(). 753 */ 754 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask); 755 goto out_disable; 756 } 757 758 /* 759 * Clear XSAVE features that are disabled in the normal CPUID. 760 */ 761 for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) { 762 if (!boot_cpu_has(xsave_cpuid_features[i])) 763 xfeatures_mask &= ~BIT(i); 764 } 765 766 xfeatures_mask &= fpu__get_supported_xfeatures_mask(); 767 768 /* Enable xstate instructions to be able to continue with initialization: */ 769 fpu__init_cpu_xstate(); 770 err = init_xstate_size(); 771 if (err) 772 goto out_disable; 773 774 /* 775 * Update info used for ptrace frames; use standard-format size and no 776 * supervisor xstates: 777 */ 778 update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR); 779 780 fpu__init_prepare_fx_sw_frame(); 781 setup_init_fpu_buf(); 782 setup_xstate_comp(); 783 print_xstate_offset_size(); 784 785 pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n", 786 xfeatures_mask, 787 fpu_kernel_xstate_size, 788 boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard"); 789 return; 790 791 out_disable: 792 /* something went wrong, try to boot without any XSAVE support */ 793 fpu__init_disable_system_xstate(); 794 } 795 796 /* 797 * Restore minimal FPU state after suspend: 798 */ 799 void fpu__resume_cpu(void) 800 { 801 /* 802 * Restore XCR0 on xsave capable CPUs: 803 */ 804 if (boot_cpu_has(X86_FEATURE_XSAVE)) 805 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 806 } 807 808 /* 809 * Given an xstate feature nr, calculate where in the xsave 810 * buffer the state is. Callers should ensure that the buffer 811 * is valid. 812 */ 813 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr) 814 { 815 if (!xfeature_enabled(xfeature_nr)) { 816 WARN_ON_FPU(1); 817 return NULL; 818 } 819 820 return (void *)xsave + xstate_comp_offsets[xfeature_nr]; 821 } 822 /* 823 * Given the xsave area and a state inside, this function returns the 824 * address of the state. 825 * 826 * This is the API that is called to get xstate address in either 827 * standard format or compacted format of xsave area. 828 * 829 * Note that if there is no data for the field in the xsave buffer 830 * this will return NULL. 831 * 832 * Inputs: 833 * xstate: the thread's storage area for all FPU data 834 * xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP, 835 * XFEATURE_SSE, etc...) 836 * Output: 837 * address of the state in the xsave area, or NULL if the 838 * field is not present in the xsave buffer. 839 */ 840 void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) 841 { 842 /* 843 * Do we even *have* xsave state? 844 */ 845 if (!boot_cpu_has(X86_FEATURE_XSAVE)) 846 return NULL; 847 848 /* 849 * We should not ever be requesting features that we 850 * have not enabled. Remember that pcntxt_mask is 851 * what we write to the XCR0 register. 852 */ 853 WARN_ONCE(!(xfeatures_mask & BIT_ULL(xfeature_nr)), 854 "get of unsupported state"); 855 /* 856 * This assumes the last 'xsave*' instruction to 857 * have requested that 'xfeature_nr' be saved. 858 * If it did not, we might be seeing and old value 859 * of the field in the buffer. 860 * 861 * This can happen because the last 'xsave' did not 862 * request that this feature be saved (unlikely) 863 * or because the "init optimization" caused it 864 * to not be saved. 865 */ 866 if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr))) 867 return NULL; 868 869 return __raw_xsave_addr(xsave, xfeature_nr); 870 } 871 EXPORT_SYMBOL_GPL(get_xsave_addr); 872 873 /* 874 * This wraps up the common operations that need to occur when retrieving 875 * data from xsave state. It first ensures that the current task was 876 * using the FPU and retrieves the data in to a buffer. It then calculates 877 * the offset of the requested field in the buffer. 878 * 879 * This function is safe to call whether the FPU is in use or not. 880 * 881 * Note that this only works on the current task. 882 * 883 * Inputs: 884 * @xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP, 885 * XFEATURE_SSE, etc...) 886 * Output: 887 * address of the state in the xsave area or NULL if the state 888 * is not present or is in its 'init state'. 889 */ 890 const void *get_xsave_field_ptr(int xfeature_nr) 891 { 892 struct fpu *fpu = ¤t->thread.fpu; 893 894 /* 895 * fpu__save() takes the CPU's xstate registers 896 * and saves them off to the 'fpu memory buffer. 897 */ 898 fpu__save(fpu); 899 900 return get_xsave_addr(&fpu->state.xsave, xfeature_nr); 901 } 902 903 #ifdef CONFIG_ARCH_HAS_PKEYS 904 905 #define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2) 906 #define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1) 907 /* 908 * This will go out and modify PKRU register to set the access 909 * rights for @pkey to @init_val. 910 */ 911 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 912 unsigned long init_val) 913 { 914 u32 old_pkru; 915 int pkey_shift = (pkey * PKRU_BITS_PER_PKEY); 916 u32 new_pkru_bits = 0; 917 918 /* 919 * This check implies XSAVE support. OSPKE only gets 920 * set if we enable XSAVE and we enable PKU in XCR0. 921 */ 922 if (!boot_cpu_has(X86_FEATURE_OSPKE)) 923 return -EINVAL; 924 925 /* Set the bits we need in PKRU: */ 926 if (init_val & PKEY_DISABLE_ACCESS) 927 new_pkru_bits |= PKRU_AD_BIT; 928 if (init_val & PKEY_DISABLE_WRITE) 929 new_pkru_bits |= PKRU_WD_BIT; 930 931 /* Shift the bits in to the correct place in PKRU for pkey: */ 932 new_pkru_bits <<= pkey_shift; 933 934 /* Get old PKRU and mask off any old bits in place: */ 935 old_pkru = read_pkru(); 936 old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift); 937 938 /* Write old part along with new part: */ 939 write_pkru(old_pkru | new_pkru_bits); 940 941 return 0; 942 } 943 #endif /* ! CONFIG_ARCH_HAS_PKEYS */ 944 945 /* 946 * Weird legacy quirk: SSE and YMM states store information in the 947 * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP 948 * area is marked as unused in the xfeatures header, we need to copy 949 * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use. 950 */ 951 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures) 952 { 953 if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM))) 954 return false; 955 956 if (xfeatures & XFEATURE_MASK_FP) 957 return false; 958 959 return true; 960 } 961 962 /* 963 * This is similar to user_regset_copyout(), but will not add offset to 964 * the source data pointer or increment pos, count, kbuf, and ubuf. 965 */ 966 static inline void 967 __copy_xstate_to_kernel(void *kbuf, const void *data, 968 unsigned int offset, unsigned int size, unsigned int size_total) 969 { 970 if (offset < size_total) { 971 unsigned int copy = min(size, size_total - offset); 972 973 memcpy(kbuf + offset, data, copy); 974 } 975 } 976 977 /* 978 * Convert from kernel XSAVES compacted format to standard format and copy 979 * to a kernel-space ptrace buffer. 980 * 981 * It supports partial copy but pos always starts from zero. This is called 982 * from xstateregs_get() and there we check the CPU has XSAVES. 983 */ 984 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 985 { 986 unsigned int offset, size; 987 struct xstate_header header; 988 int i; 989 990 /* 991 * Currently copy_regset_to_user() starts from pos 0: 992 */ 993 if (unlikely(offset_start != 0)) 994 return -EFAULT; 995 996 /* 997 * The destination is a ptrace buffer; we put in only user xstates: 998 */ 999 memset(&header, 0, sizeof(header)); 1000 header.xfeatures = xsave->header.xfeatures; 1001 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1002 1003 /* 1004 * Copy xregs_state->header: 1005 */ 1006 offset = offsetof(struct xregs_state, header); 1007 size = sizeof(header); 1008 1009 __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total); 1010 1011 for (i = 0; i < XFEATURE_MAX; i++) { 1012 /* 1013 * Copy only in-use xstates: 1014 */ 1015 if ((header.xfeatures >> i) & 1) { 1016 void *src = __raw_xsave_addr(xsave, i); 1017 1018 offset = xstate_offsets[i]; 1019 size = xstate_sizes[i]; 1020 1021 /* The next component has to fit fully into the output buffer: */ 1022 if (offset + size > size_total) 1023 break; 1024 1025 __copy_xstate_to_kernel(kbuf, src, offset, size, size_total); 1026 } 1027 1028 } 1029 1030 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1031 offset = offsetof(struct fxregs_state, mxcsr); 1032 size = MXCSR_AND_FLAGS_SIZE; 1033 __copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total); 1034 } 1035 1036 /* 1037 * Fill xsave->i387.sw_reserved value for ptrace frame: 1038 */ 1039 offset = offsetof(struct fxregs_state, sw_reserved); 1040 size = sizeof(xstate_fx_sw_bytes); 1041 1042 __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total); 1043 1044 return 0; 1045 } 1046 1047 static inline int 1048 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total) 1049 { 1050 if (!size) 1051 return 0; 1052 1053 if (offset < size_total) { 1054 unsigned int copy = min(size, size_total - offset); 1055 1056 if (__copy_to_user(ubuf + offset, data, copy)) 1057 return -EFAULT; 1058 } 1059 return 0; 1060 } 1061 1062 /* 1063 * Convert from kernel XSAVES compacted format to standard format and copy 1064 * to a user-space buffer. It supports partial copy but pos always starts from 1065 * zero. This is called from xstateregs_get() and there we check the CPU 1066 * has XSAVES. 1067 */ 1068 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 1069 { 1070 unsigned int offset, size; 1071 int ret, i; 1072 struct xstate_header header; 1073 1074 /* 1075 * Currently copy_regset_to_user() starts from pos 0: 1076 */ 1077 if (unlikely(offset_start != 0)) 1078 return -EFAULT; 1079 1080 /* 1081 * The destination is a ptrace buffer; we put in only user xstates: 1082 */ 1083 memset(&header, 0, sizeof(header)); 1084 header.xfeatures = xsave->header.xfeatures; 1085 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1086 1087 /* 1088 * Copy xregs_state->header: 1089 */ 1090 offset = offsetof(struct xregs_state, header); 1091 size = sizeof(header); 1092 1093 ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total); 1094 if (ret) 1095 return ret; 1096 1097 for (i = 0; i < XFEATURE_MAX; i++) { 1098 /* 1099 * Copy only in-use xstates: 1100 */ 1101 if ((header.xfeatures >> i) & 1) { 1102 void *src = __raw_xsave_addr(xsave, i); 1103 1104 offset = xstate_offsets[i]; 1105 size = xstate_sizes[i]; 1106 1107 /* The next component has to fit fully into the output buffer: */ 1108 if (offset + size > size_total) 1109 break; 1110 1111 ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total); 1112 if (ret) 1113 return ret; 1114 } 1115 1116 } 1117 1118 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1119 offset = offsetof(struct fxregs_state, mxcsr); 1120 size = MXCSR_AND_FLAGS_SIZE; 1121 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total); 1122 } 1123 1124 /* 1125 * Fill xsave->i387.sw_reserved value for ptrace frame: 1126 */ 1127 offset = offsetof(struct fxregs_state, sw_reserved); 1128 size = sizeof(xstate_fx_sw_bytes); 1129 1130 ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total); 1131 if (ret) 1132 return ret; 1133 1134 return 0; 1135 } 1136 1137 /* 1138 * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format 1139 * and copy to the target thread. This is called from xstateregs_set(). 1140 */ 1141 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) 1142 { 1143 unsigned int offset, size; 1144 int i; 1145 struct xstate_header hdr; 1146 1147 offset = offsetof(struct xregs_state, header); 1148 size = sizeof(hdr); 1149 1150 memcpy(&hdr, kbuf + offset, size); 1151 1152 if (validate_xstate_header(&hdr)) 1153 return -EINVAL; 1154 1155 for (i = 0; i < XFEATURE_MAX; i++) { 1156 u64 mask = ((u64)1 << i); 1157 1158 if (hdr.xfeatures & mask) { 1159 void *dst = __raw_xsave_addr(xsave, i); 1160 1161 offset = xstate_offsets[i]; 1162 size = xstate_sizes[i]; 1163 1164 memcpy(dst, kbuf + offset, size); 1165 } 1166 } 1167 1168 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1169 offset = offsetof(struct fxregs_state, mxcsr); 1170 size = MXCSR_AND_FLAGS_SIZE; 1171 memcpy(&xsave->i387.mxcsr, kbuf + offset, size); 1172 } 1173 1174 /* 1175 * The state that came in from userspace was user-state only. 1176 * Mask all the user states out of 'xfeatures': 1177 */ 1178 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1179 1180 /* 1181 * Add back in the features that came in from userspace: 1182 */ 1183 xsave->header.xfeatures |= hdr.xfeatures; 1184 1185 return 0; 1186 } 1187 1188 /* 1189 * Convert from a ptrace or sigreturn standard-format user-space buffer to 1190 * kernel XSAVES format and copy to the target thread. This is called from 1191 * xstateregs_set(), as well as potentially from the sigreturn() and 1192 * rt_sigreturn() system calls. 1193 */ 1194 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) 1195 { 1196 unsigned int offset, size; 1197 int i; 1198 struct xstate_header hdr; 1199 1200 offset = offsetof(struct xregs_state, header); 1201 size = sizeof(hdr); 1202 1203 if (__copy_from_user(&hdr, ubuf + offset, size)) 1204 return -EFAULT; 1205 1206 if (validate_xstate_header(&hdr)) 1207 return -EINVAL; 1208 1209 for (i = 0; i < XFEATURE_MAX; i++) { 1210 u64 mask = ((u64)1 << i); 1211 1212 if (hdr.xfeatures & mask) { 1213 void *dst = __raw_xsave_addr(xsave, i); 1214 1215 offset = xstate_offsets[i]; 1216 size = xstate_sizes[i]; 1217 1218 if (__copy_from_user(dst, ubuf + offset, size)) 1219 return -EFAULT; 1220 } 1221 } 1222 1223 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1224 offset = offsetof(struct fxregs_state, mxcsr); 1225 size = MXCSR_AND_FLAGS_SIZE; 1226 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size)) 1227 return -EFAULT; 1228 } 1229 1230 /* 1231 * The state that came in from userspace was user-state only. 1232 * Mask all the user states out of 'xfeatures': 1233 */ 1234 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1235 1236 /* 1237 * Add back in the features that came in from userspace: 1238 */ 1239 xsave->header.xfeatures |= hdr.xfeatures; 1240 1241 return 0; 1242 } 1243