1 /* 2 * xsave/xrstor support. 3 * 4 * Author: Suresh Siddha <suresh.b.siddha@intel.com> 5 */ 6 #include <linux/compat.h> 7 #include <linux/cpu.h> 8 #include <linux/mman.h> 9 #include <linux/pkeys.h> 10 11 #include <asm/fpu/api.h> 12 #include <asm/fpu/internal.h> 13 #include <asm/fpu/signal.h> 14 #include <asm/fpu/regset.h> 15 #include <asm/fpu/xstate.h> 16 17 #include <asm/tlbflush.h> 18 #include <asm/cpufeature.h> 19 20 /* 21 * Although we spell it out in here, the Processor Trace 22 * xfeature is completely unused. We use other mechanisms 23 * to save/restore PT state in Linux. 24 */ 25 static const char *xfeature_names[] = 26 { 27 "x87 floating point registers" , 28 "SSE registers" , 29 "AVX registers" , 30 "MPX bounds registers" , 31 "MPX CSR" , 32 "AVX-512 opmask" , 33 "AVX-512 Hi256" , 34 "AVX-512 ZMM_Hi256" , 35 "Processor Trace (unused)" , 36 "Protection Keys User registers", 37 "unknown xstate feature" , 38 }; 39 40 static short xsave_cpuid_features[] __initdata = { 41 X86_FEATURE_FPU, 42 X86_FEATURE_XMM, 43 X86_FEATURE_AVX, 44 X86_FEATURE_MPX, 45 X86_FEATURE_MPX, 46 X86_FEATURE_AVX512F, 47 X86_FEATURE_AVX512F, 48 X86_FEATURE_AVX512F, 49 X86_FEATURE_INTEL_PT, 50 X86_FEATURE_PKU, 51 }; 52 53 /* 54 * Mask of xstate features supported by the CPU and the kernel: 55 */ 56 u64 xfeatures_mask __read_mostly; 57 58 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 59 static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; 60 static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; 61 62 /* 63 * The XSAVE area of kernel can be in standard or compacted format; 64 * it is always in standard format for user mode. This is the user 65 * mode standard format size used for signal and ptrace frames. 66 */ 67 unsigned int fpu_user_xstate_size; 68 69 /* 70 * Clear all of the X86_FEATURE_* bits that are unavailable 71 * when the CPU has no XSAVE support. 72 */ 73 void fpu__xstate_clear_all_cpu_caps(void) 74 { 75 setup_clear_cpu_cap(X86_FEATURE_XSAVE); 76 } 77 78 /* 79 * Return whether the system supports a given xfeature. 80 * 81 * Also return the name of the (most advanced) feature that the caller requested: 82 */ 83 int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) 84 { 85 u64 xfeatures_missing = xfeatures_needed & ~xfeatures_mask; 86 87 if (unlikely(feature_name)) { 88 long xfeature_idx, max_idx; 89 u64 xfeatures_print; 90 /* 91 * So we use FLS here to be able to print the most advanced 92 * feature that was requested but is missing. So if a driver 93 * asks about "XFEATURE_MASK_SSE | XFEATURE_MASK_YMM" we'll print the 94 * missing AVX feature - this is the most informative message 95 * to users: 96 */ 97 if (xfeatures_missing) 98 xfeatures_print = xfeatures_missing; 99 else 100 xfeatures_print = xfeatures_needed; 101 102 xfeature_idx = fls64(xfeatures_print)-1; 103 max_idx = ARRAY_SIZE(xfeature_names)-1; 104 xfeature_idx = min(xfeature_idx, max_idx); 105 106 *feature_name = xfeature_names[xfeature_idx]; 107 } 108 109 if (xfeatures_missing) 110 return 0; 111 112 return 1; 113 } 114 EXPORT_SYMBOL_GPL(cpu_has_xfeatures); 115 116 static int xfeature_is_supervisor(int xfeature_nr) 117 { 118 /* 119 * We currently do not support supervisor states, but if 120 * we did, we could find out like this. 121 * 122 * SDM says: If state component 'i' is a user state component, 123 * ECX[0] return 0; if state component i is a supervisor 124 * state component, ECX[0] returns 1. 125 */ 126 u32 eax, ebx, ecx, edx; 127 128 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 129 return !!(ecx & 1); 130 } 131 132 static int xfeature_is_user(int xfeature_nr) 133 { 134 return !xfeature_is_supervisor(xfeature_nr); 135 } 136 137 /* 138 * When executing XSAVEOPT (or other optimized XSAVE instructions), if 139 * a processor implementation detects that an FPU state component is still 140 * (or is again) in its initialized state, it may clear the corresponding 141 * bit in the header.xfeatures field, and can skip the writeout of registers 142 * to the corresponding memory layout. 143 * 144 * This means that when the bit is zero, the state component might still contain 145 * some previous - non-initialized register state. 146 * 147 * Before writing xstate information to user-space we sanitize those components, 148 * to always ensure that the memory layout of a feature will be in the init state 149 * if the corresponding header bit is zero. This is to ensure that user-space doesn't 150 * see some stale state in the memory layout during signal handling, debugging etc. 151 */ 152 void fpstate_sanitize_xstate(struct fpu *fpu) 153 { 154 struct fxregs_state *fx = &fpu->state.fxsave; 155 int feature_bit; 156 u64 xfeatures; 157 158 if (!use_xsaveopt()) 159 return; 160 161 xfeatures = fpu->state.xsave.header.xfeatures; 162 163 /* 164 * None of the feature bits are in init state. So nothing else 165 * to do for us, as the memory layout is up to date. 166 */ 167 if ((xfeatures & xfeatures_mask) == xfeatures_mask) 168 return; 169 170 /* 171 * FP is in init state 172 */ 173 if (!(xfeatures & XFEATURE_MASK_FP)) { 174 fx->cwd = 0x37f; 175 fx->swd = 0; 176 fx->twd = 0; 177 fx->fop = 0; 178 fx->rip = 0; 179 fx->rdp = 0; 180 memset(&fx->st_space[0], 0, 128); 181 } 182 183 /* 184 * SSE is in init state 185 */ 186 if (!(xfeatures & XFEATURE_MASK_SSE)) 187 memset(&fx->xmm_space[0], 0, 256); 188 189 /* 190 * First two features are FPU and SSE, which above we handled 191 * in a special way already: 192 */ 193 feature_bit = 0x2; 194 xfeatures = (xfeatures_mask & ~xfeatures) >> 2; 195 196 /* 197 * Update all the remaining memory layouts according to their 198 * standard xstate layout, if their header bit is in the init 199 * state: 200 */ 201 while (xfeatures) { 202 if (xfeatures & 0x1) { 203 int offset = xstate_comp_offsets[feature_bit]; 204 int size = xstate_sizes[feature_bit]; 205 206 memcpy((void *)fx + offset, 207 (void *)&init_fpstate.xsave + offset, 208 size); 209 } 210 211 xfeatures >>= 1; 212 feature_bit++; 213 } 214 } 215 216 /* 217 * Enable the extended processor state save/restore feature. 218 * Called once per CPU onlining. 219 */ 220 void fpu__init_cpu_xstate(void) 221 { 222 if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) 223 return; 224 /* 225 * Make it clear that XSAVES supervisor states are not yet 226 * implemented should anyone expect it to work by changing 227 * bits in XFEATURE_MASK_* macros and XCR0. 228 */ 229 WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), 230 "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); 231 232 xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; 233 234 cr4_set_bits(X86_CR4_OSXSAVE); 235 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 236 } 237 238 /* 239 * Note that in the future we will likely need a pair of 240 * functions here: one for user xstates and the other for 241 * system xstates. For now, they are the same. 242 */ 243 static int xfeature_enabled(enum xfeature xfeature) 244 { 245 return !!(xfeatures_mask & (1UL << xfeature)); 246 } 247 248 /* 249 * Record the offsets and sizes of various xstates contained 250 * in the XSAVE state memory layout. 251 */ 252 static void __init setup_xstate_features(void) 253 { 254 u32 eax, ebx, ecx, edx, i; 255 /* start at the beginnning of the "extended state" */ 256 unsigned int last_good_offset = offsetof(struct xregs_state, 257 extended_state_area); 258 /* 259 * The FP xstates and SSE xstates are legacy states. They are always 260 * in the fixed offsets in the xsave area in either compacted form 261 * or standard form. 262 */ 263 xstate_offsets[0] = 0; 264 xstate_sizes[0] = offsetof(struct fxregs_state, xmm_space); 265 xstate_offsets[1] = xstate_sizes[0]; 266 xstate_sizes[1] = FIELD_SIZEOF(struct fxregs_state, xmm_space); 267 268 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 269 if (!xfeature_enabled(i)) 270 continue; 271 272 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); 273 274 /* 275 * If an xfeature is supervisor state, the offset 276 * in EBX is invalid. We leave it to -1. 277 */ 278 if (xfeature_is_user(i)) 279 xstate_offsets[i] = ebx; 280 281 xstate_sizes[i] = eax; 282 /* 283 * In our xstate size checks, we assume that the 284 * highest-numbered xstate feature has the 285 * highest offset in the buffer. Ensure it does. 286 */ 287 WARN_ONCE(last_good_offset > xstate_offsets[i], 288 "x86/fpu: misordered xstate at %d\n", last_good_offset); 289 last_good_offset = xstate_offsets[i]; 290 } 291 } 292 293 static void __init print_xstate_feature(u64 xstate_mask) 294 { 295 const char *feature_name; 296 297 if (cpu_has_xfeatures(xstate_mask, &feature_name)) 298 pr_info("x86/fpu: Supporting XSAVE feature 0x%03Lx: '%s'\n", xstate_mask, feature_name); 299 } 300 301 /* 302 * Print out all the supported xstate features: 303 */ 304 static void __init print_xstate_features(void) 305 { 306 print_xstate_feature(XFEATURE_MASK_FP); 307 print_xstate_feature(XFEATURE_MASK_SSE); 308 print_xstate_feature(XFEATURE_MASK_YMM); 309 print_xstate_feature(XFEATURE_MASK_BNDREGS); 310 print_xstate_feature(XFEATURE_MASK_BNDCSR); 311 print_xstate_feature(XFEATURE_MASK_OPMASK); 312 print_xstate_feature(XFEATURE_MASK_ZMM_Hi256); 313 print_xstate_feature(XFEATURE_MASK_Hi16_ZMM); 314 print_xstate_feature(XFEATURE_MASK_PKRU); 315 } 316 317 /* 318 * This check is important because it is easy to get XSTATE_* 319 * confused with XSTATE_BIT_*. 320 */ 321 #define CHECK_XFEATURE(nr) do { \ 322 WARN_ON(nr < FIRST_EXTENDED_XFEATURE); \ 323 WARN_ON(nr >= XFEATURE_MAX); \ 324 } while (0) 325 326 /* 327 * We could cache this like xstate_size[], but we only use 328 * it here, so it would be a waste of space. 329 */ 330 static int xfeature_is_aligned(int xfeature_nr) 331 { 332 u32 eax, ebx, ecx, edx; 333 334 CHECK_XFEATURE(xfeature_nr); 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 aread. 348 */ 349 static void __init setup_xstate_comp(void) 350 { 351 unsigned int xstate_comp_sizes[sizeof(xfeatures_mask)*8]; 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[0] = 0; 360 xstate_comp_offsets[1] = offsetof(struct fxregs_state, xmm_space); 361 362 if (!boot_cpu_has(X86_FEATURE_XSAVES)) { 363 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 364 if (xfeature_enabled(i)) { 365 xstate_comp_offsets[i] = xstate_offsets[i]; 366 xstate_comp_sizes[i] = xstate_sizes[i]; 367 } 368 } 369 return; 370 } 371 372 xstate_comp_offsets[FIRST_EXTENDED_XFEATURE] = 373 FXSAVE_SIZE + XSAVE_HDR_SIZE; 374 375 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 376 if (xfeature_enabled(i)) 377 xstate_comp_sizes[i] = xstate_sizes[i]; 378 else 379 xstate_comp_sizes[i] = 0; 380 381 if (i > FIRST_EXTENDED_XFEATURE) { 382 xstate_comp_offsets[i] = xstate_comp_offsets[i-1] 383 + xstate_comp_sizes[i-1]; 384 385 if (xfeature_is_aligned(i)) 386 xstate_comp_offsets[i] = 387 ALIGN(xstate_comp_offsets[i], 64); 388 } 389 } 390 } 391 392 /* 393 * Print out xstate component offsets and sizes 394 */ 395 static void __init print_xstate_offset_size(void) 396 { 397 int i; 398 399 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 400 if (!xfeature_enabled(i)) 401 continue; 402 pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n", 403 i, xstate_comp_offsets[i], i, xstate_sizes[i]); 404 } 405 } 406 407 /* 408 * setup the xstate image representing the init state 409 */ 410 static void __init setup_init_fpu_buf(void) 411 { 412 static int on_boot_cpu __initdata = 1; 413 414 WARN_ON_FPU(!on_boot_cpu); 415 on_boot_cpu = 0; 416 417 if (!boot_cpu_has(X86_FEATURE_XSAVE)) 418 return; 419 420 setup_xstate_features(); 421 print_xstate_features(); 422 423 if (boot_cpu_has(X86_FEATURE_XSAVES)) 424 init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; 425 426 /* 427 * Init all the features state with header.xfeatures being 0x0 428 */ 429 copy_kernel_to_xregs_booting(&init_fpstate.xsave); 430 431 /* 432 * Dump the init state again. This is to identify the init state 433 * of any feature which is not represented by all zero's. 434 */ 435 copy_xregs_to_kernel_booting(&init_fpstate.xsave); 436 } 437 438 static int xfeature_uncompacted_offset(int xfeature_nr) 439 { 440 u32 eax, ebx, ecx, edx; 441 442 /* 443 * Only XSAVES supports supervisor states and it uses compacted 444 * format. Checking a supervisor state's uncompacted offset is 445 * an error. 446 */ 447 if (XFEATURE_MASK_SUPERVISOR & (1 << xfeature_nr)) { 448 WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); 449 return -1; 450 } 451 452 CHECK_XFEATURE(xfeature_nr); 453 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 454 return ebx; 455 } 456 457 static int xfeature_size(int xfeature_nr) 458 { 459 u32 eax, ebx, ecx, edx; 460 461 CHECK_XFEATURE(xfeature_nr); 462 cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); 463 return eax; 464 } 465 466 /* 467 * 'XSAVES' implies two different things: 468 * 1. saving of supervisor/system state 469 * 2. using the compacted format 470 * 471 * Use this function when dealing with the compacted format so 472 * that it is obvious which aspect of 'XSAVES' is being handled 473 * by the calling code. 474 */ 475 int using_compacted_format(void) 476 { 477 return boot_cpu_has(X86_FEATURE_XSAVES); 478 } 479 480 /* Validate an xstate header supplied by userspace (ptrace or sigreturn) */ 481 int validate_xstate_header(const struct xstate_header *hdr) 482 { 483 /* No unknown or supervisor features may be set */ 484 if (hdr->xfeatures & (~xfeatures_mask | XFEATURE_MASK_SUPERVISOR)) 485 return -EINVAL; 486 487 /* Userspace must use the uncompacted format */ 488 if (hdr->xcomp_bv) 489 return -EINVAL; 490 491 /* 492 * If 'reserved' is shrunken to add a new field, make sure to validate 493 * that new field here! 494 */ 495 BUILD_BUG_ON(sizeof(hdr->reserved) != 48); 496 497 /* No reserved bits may be set */ 498 if (memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved))) 499 return -EINVAL; 500 501 return 0; 502 } 503 504 static void __xstate_dump_leaves(void) 505 { 506 int i; 507 u32 eax, ebx, ecx, edx; 508 static int should_dump = 1; 509 510 if (!should_dump) 511 return; 512 should_dump = 0; 513 /* 514 * Dump out a few leaves past the ones that we support 515 * just in case there are some goodies up there 516 */ 517 for (i = 0; i < XFEATURE_MAX + 10; i++) { 518 cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); 519 pr_warn("CPUID[%02x, %02x]: eax=%08x ebx=%08x ecx=%08x edx=%08x\n", 520 XSTATE_CPUID, i, eax, ebx, ecx, edx); 521 } 522 } 523 524 #define XSTATE_WARN_ON(x) do { \ 525 if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) { \ 526 __xstate_dump_leaves(); \ 527 } \ 528 } while (0) 529 530 #define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \ 531 if ((nr == nr_macro) && \ 532 WARN_ONCE(sz != sizeof(__struct), \ 533 "%s: struct is %zu bytes, cpu state %d bytes\n", \ 534 __stringify(nr_macro), sizeof(__struct), sz)) { \ 535 __xstate_dump_leaves(); \ 536 } \ 537 } while (0) 538 539 /* 540 * We have a C struct for each 'xstate'. We need to ensure 541 * that our software representation matches what the CPU 542 * tells us about the state's size. 543 */ 544 static void check_xstate_against_struct(int nr) 545 { 546 /* 547 * Ask the CPU for the size of the state. 548 */ 549 int sz = xfeature_size(nr); 550 /* 551 * Match each CPU state with the corresponding software 552 * structure. 553 */ 554 XCHECK_SZ(sz, nr, XFEATURE_YMM, struct ymmh_struct); 555 XCHECK_SZ(sz, nr, XFEATURE_BNDREGS, struct mpx_bndreg_state); 556 XCHECK_SZ(sz, nr, XFEATURE_BNDCSR, struct mpx_bndcsr_state); 557 XCHECK_SZ(sz, nr, XFEATURE_OPMASK, struct avx_512_opmask_state); 558 XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state); 559 XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state); 560 XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state); 561 562 /* 563 * Make *SURE* to add any feature numbers in below if 564 * there are "holes" in the xsave state component 565 * numbers. 566 */ 567 if ((nr < XFEATURE_YMM) || 568 (nr >= XFEATURE_MAX) || 569 (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) { 570 WARN_ONCE(1, "no structure for xstate: %d\n", nr); 571 XSTATE_WARN_ON(1); 572 } 573 } 574 575 /* 576 * This essentially double-checks what the cpu told us about 577 * how large the XSAVE buffer needs to be. We are recalculating 578 * it to be safe. 579 */ 580 static void do_extra_xstate_size_checks(void) 581 { 582 int paranoid_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; 583 int i; 584 585 for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { 586 if (!xfeature_enabled(i)) 587 continue; 588 589 check_xstate_against_struct(i); 590 /* 591 * Supervisor state components can be managed only by 592 * XSAVES, which is compacted-format only. 593 */ 594 if (!using_compacted_format()) 595 XSTATE_WARN_ON(xfeature_is_supervisor(i)); 596 597 /* Align from the end of the previous feature */ 598 if (xfeature_is_aligned(i)) 599 paranoid_xstate_size = ALIGN(paranoid_xstate_size, 64); 600 /* 601 * The offset of a given state in the non-compacted 602 * format is given to us in a CPUID leaf. We check 603 * them for being ordered (increasing offsets) in 604 * setup_xstate_features(). 605 */ 606 if (!using_compacted_format()) 607 paranoid_xstate_size = xfeature_uncompacted_offset(i); 608 /* 609 * The compacted-format offset always depends on where 610 * the previous state ended. 611 */ 612 paranoid_xstate_size += xfeature_size(i); 613 } 614 XSTATE_WARN_ON(paranoid_xstate_size != fpu_kernel_xstate_size); 615 } 616 617 618 /* 619 * Get total size of enabled xstates in XCR0/xfeatures_mask. 620 * 621 * Note the SDM's wording here. "sub-function 0" only enumerates 622 * the size of the *user* states. If we use it to size a buffer 623 * that we use 'XSAVES' on, we could potentially overflow the 624 * buffer because 'XSAVES' saves system states too. 625 * 626 * Note that we do not currently set any bits on IA32_XSS so 627 * 'XCR0 | IA32_XSS == XCR0' for now. 628 */ 629 static unsigned int __init get_xsaves_size(void) 630 { 631 unsigned int eax, ebx, ecx, edx; 632 /* 633 * - CPUID function 0DH, sub-function 1: 634 * EBX enumerates the size (in bytes) required by 635 * the XSAVES instruction for an XSAVE area 636 * containing all the state components 637 * corresponding to bits currently set in 638 * XCR0 | IA32_XSS. 639 */ 640 cpuid_count(XSTATE_CPUID, 1, &eax, &ebx, &ecx, &edx); 641 return ebx; 642 } 643 644 static unsigned int __init get_xsave_size(void) 645 { 646 unsigned int eax, ebx, ecx, edx; 647 /* 648 * - CPUID function 0DH, sub-function 0: 649 * EBX enumerates the size (in bytes) required by 650 * the XSAVE instruction for an XSAVE area 651 * containing all the *user* state components 652 * corresponding to bits currently set in XCR0. 653 */ 654 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 655 return ebx; 656 } 657 658 /* 659 * Will the runtime-enumerated 'xstate_size' fit in the init 660 * task's statically-allocated buffer? 661 */ 662 static bool is_supported_xstate_size(unsigned int test_xstate_size) 663 { 664 if (test_xstate_size <= sizeof(union fpregs_state)) 665 return true; 666 667 pr_warn("x86/fpu: xstate buffer too small (%zu < %d), disabling xsave\n", 668 sizeof(union fpregs_state), test_xstate_size); 669 return false; 670 } 671 672 static int init_xstate_size(void) 673 { 674 /* Recompute the context size for enabled features: */ 675 unsigned int possible_xstate_size; 676 unsigned int xsave_size; 677 678 xsave_size = get_xsave_size(); 679 680 if (boot_cpu_has(X86_FEATURE_XSAVES)) 681 possible_xstate_size = get_xsaves_size(); 682 else 683 possible_xstate_size = xsave_size; 684 685 /* Ensure we have the space to store all enabled: */ 686 if (!is_supported_xstate_size(possible_xstate_size)) 687 return -EINVAL; 688 689 /* 690 * The size is OK, we are definitely going to use xsave, 691 * make it known to the world that we need more space. 692 */ 693 fpu_kernel_xstate_size = possible_xstate_size; 694 do_extra_xstate_size_checks(); 695 696 /* 697 * User space is always in standard format. 698 */ 699 fpu_user_xstate_size = xsave_size; 700 return 0; 701 } 702 703 /* 704 * We enabled the XSAVE hardware, but something went wrong and 705 * we can not use it. Disable it. 706 */ 707 static void fpu__init_disable_system_xstate(void) 708 { 709 xfeatures_mask = 0; 710 cr4_clear_bits(X86_CR4_OSXSAVE); 711 fpu__xstate_clear_all_cpu_caps(); 712 } 713 714 /* 715 * Enable and initialize the xsave feature. 716 * Called once per system bootup. 717 */ 718 void __init fpu__init_system_xstate(void) 719 { 720 unsigned int eax, ebx, ecx, edx; 721 static int on_boot_cpu __initdata = 1; 722 int err; 723 int i; 724 725 WARN_ON_FPU(!on_boot_cpu); 726 on_boot_cpu = 0; 727 728 if (!boot_cpu_has(X86_FEATURE_FPU)) { 729 pr_info("x86/fpu: No FPU detected\n"); 730 return; 731 } 732 733 if (!boot_cpu_has(X86_FEATURE_XSAVE)) { 734 pr_info("x86/fpu: x87 FPU will use %s\n", 735 boot_cpu_has(X86_FEATURE_FXSR) ? "FXSAVE" : "FSAVE"); 736 return; 737 } 738 739 if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { 740 WARN_ON_FPU(1); 741 return; 742 } 743 744 cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); 745 xfeatures_mask = eax + ((u64)edx << 32); 746 747 if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) { 748 /* 749 * This indicates that something really unexpected happened 750 * with the enumeration. Disable XSAVE and try to continue 751 * booting without it. This is too early to BUG(). 752 */ 753 pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate features: 0x%llx.\n", xfeatures_mask); 754 goto out_disable; 755 } 756 757 /* 758 * Clear XSAVE features that are disabled in the normal CPUID. 759 */ 760 for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) { 761 if (!boot_cpu_has(xsave_cpuid_features[i])) 762 xfeatures_mask &= ~BIT(i); 763 } 764 765 xfeatures_mask &= fpu__get_supported_xfeatures_mask(); 766 767 /* Enable xstate instructions to be able to continue with initialization: */ 768 fpu__init_cpu_xstate(); 769 err = init_xstate_size(); 770 if (err) 771 goto out_disable; 772 773 /* 774 * Update info used for ptrace frames; use standard-format size and no 775 * supervisor xstates: 776 */ 777 update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR); 778 779 fpu__init_prepare_fx_sw_frame(); 780 setup_init_fpu_buf(); 781 setup_xstate_comp(); 782 print_xstate_offset_size(); 783 784 pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n", 785 xfeatures_mask, 786 fpu_kernel_xstate_size, 787 boot_cpu_has(X86_FEATURE_XSAVES) ? "compacted" : "standard"); 788 return; 789 790 out_disable: 791 /* something went wrong, try to boot without any XSAVE support */ 792 fpu__init_disable_system_xstate(); 793 } 794 795 /* 796 * Restore minimal FPU state after suspend: 797 */ 798 void fpu__resume_cpu(void) 799 { 800 /* 801 * Restore XCR0 on xsave capable CPUs: 802 */ 803 if (boot_cpu_has(X86_FEATURE_XSAVE)) 804 xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask); 805 } 806 807 /* 808 * Given an xstate feature mask, calculate where in the xsave 809 * buffer the state is. Callers should ensure that the buffer 810 * is valid. 811 * 812 * Note: does not work for compacted buffers. 813 */ 814 void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask) 815 { 816 int feature_nr = fls64(xstate_feature_mask) - 1; 817 818 if (!xfeature_enabled(feature_nr)) { 819 WARN_ON_FPU(1); 820 return NULL; 821 } 822 823 return (void *)xsave + xstate_comp_offsets[feature_nr]; 824 } 825 /* 826 * Given the xsave area and a state inside, this function returns the 827 * address of the state. 828 * 829 * This is the API that is called to get xstate address in either 830 * standard format or compacted format of xsave area. 831 * 832 * Note that if there is no data for the field in the xsave buffer 833 * this will return NULL. 834 * 835 * Inputs: 836 * xstate: the thread's storage area for all FPU data 837 * xstate_feature: state which is defined in xsave.h (e.g. 838 * XFEATURE_MASK_FP, XFEATURE_MASK_SSE, etc...) 839 * Output: 840 * address of the state in the xsave area, or NULL if the 841 * field is not present in the xsave buffer. 842 */ 843 void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature) 844 { 845 /* 846 * Do we even *have* xsave state? 847 */ 848 if (!boot_cpu_has(X86_FEATURE_XSAVE)) 849 return NULL; 850 851 /* 852 * We should not ever be requesting features that we 853 * have not enabled. Remember that pcntxt_mask is 854 * what we write to the XCR0 register. 855 */ 856 WARN_ONCE(!(xfeatures_mask & xstate_feature), 857 "get of unsupported state"); 858 /* 859 * This assumes the last 'xsave*' instruction to 860 * have requested that 'xstate_feature' be saved. 861 * If it did not, we might be seeing and old value 862 * of the field in the buffer. 863 * 864 * This can happen because the last 'xsave' did not 865 * request that this feature be saved (unlikely) 866 * or because the "init optimization" caused it 867 * to not be saved. 868 */ 869 if (!(xsave->header.xfeatures & xstate_feature)) 870 return NULL; 871 872 return __raw_xsave_addr(xsave, xstate_feature); 873 } 874 EXPORT_SYMBOL_GPL(get_xsave_addr); 875 876 /* 877 * This wraps up the common operations that need to occur when retrieving 878 * data from xsave state. It first ensures that the current task was 879 * using the FPU and retrieves the data in to a buffer. It then calculates 880 * the offset of the requested field in the buffer. 881 * 882 * This function is safe to call whether the FPU is in use or not. 883 * 884 * Note that this only works on the current task. 885 * 886 * Inputs: 887 * @xsave_state: state which is defined in xsave.h (e.g. XFEATURE_MASK_FP, 888 * XFEATURE_MASK_SSE, etc...) 889 * Output: 890 * address of the state in the xsave area or NULL if the state 891 * is not present or is in its 'init state'. 892 */ 893 const void *get_xsave_field_ptr(int xsave_state) 894 { 895 struct fpu *fpu = ¤t->thread.fpu; 896 897 if (!fpu->initialized) 898 return NULL; 899 /* 900 * fpu__save() takes the CPU's xstate registers 901 * and saves them off to the 'fpu memory buffer. 902 */ 903 fpu__save(fpu); 904 905 return get_xsave_addr(&fpu->state.xsave, xsave_state); 906 } 907 908 #ifdef CONFIG_ARCH_HAS_PKEYS 909 910 #define NR_VALID_PKRU_BITS (CONFIG_NR_PROTECTION_KEYS * 2) 911 #define PKRU_VALID_MASK (NR_VALID_PKRU_BITS - 1) 912 /* 913 * This will go out and modify PKRU register to set the access 914 * rights for @pkey to @init_val. 915 */ 916 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 917 unsigned long init_val) 918 { 919 u32 old_pkru; 920 int pkey_shift = (pkey * PKRU_BITS_PER_PKEY); 921 u32 new_pkru_bits = 0; 922 923 /* 924 * This check implies XSAVE support. OSPKE only gets 925 * set if we enable XSAVE and we enable PKU in XCR0. 926 */ 927 if (!boot_cpu_has(X86_FEATURE_OSPKE)) 928 return -EINVAL; 929 930 /* Set the bits we need in PKRU: */ 931 if (init_val & PKEY_DISABLE_ACCESS) 932 new_pkru_bits |= PKRU_AD_BIT; 933 if (init_val & PKEY_DISABLE_WRITE) 934 new_pkru_bits |= PKRU_WD_BIT; 935 936 /* Shift the bits in to the correct place in PKRU for pkey: */ 937 new_pkru_bits <<= pkey_shift; 938 939 /* Get old PKRU and mask off any old bits in place: */ 940 old_pkru = read_pkru(); 941 old_pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift); 942 943 /* Write old part along with new part: */ 944 write_pkru(old_pkru | new_pkru_bits); 945 946 return 0; 947 } 948 #endif /* ! CONFIG_ARCH_HAS_PKEYS */ 949 950 /* 951 * Weird legacy quirk: SSE and YMM states store information in the 952 * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP 953 * area is marked as unused in the xfeatures header, we need to copy 954 * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use. 955 */ 956 static inline bool xfeatures_mxcsr_quirk(u64 xfeatures) 957 { 958 if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM))) 959 return false; 960 961 if (xfeatures & XFEATURE_MASK_FP) 962 return false; 963 964 return true; 965 } 966 967 /* 968 * This is similar to user_regset_copyout(), but will not add offset to 969 * the source data pointer or increment pos, count, kbuf, and ubuf. 970 */ 971 static inline void 972 __copy_xstate_to_kernel(void *kbuf, const void *data, 973 unsigned int offset, unsigned int size, unsigned int size_total) 974 { 975 if (offset < size_total) { 976 unsigned int copy = min(size, size_total - offset); 977 978 memcpy(kbuf + offset, data, copy); 979 } 980 } 981 982 /* 983 * Convert from kernel XSAVES compacted format to standard format and copy 984 * to a kernel-space ptrace buffer. 985 * 986 * It supports partial copy but pos always starts from zero. This is called 987 * from xstateregs_get() and there we check the CPU has XSAVES. 988 */ 989 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 990 { 991 unsigned int offset, size; 992 struct xstate_header header; 993 int i; 994 995 /* 996 * Currently copy_regset_to_user() starts from pos 0: 997 */ 998 if (unlikely(offset_start != 0)) 999 return -EFAULT; 1000 1001 /* 1002 * The destination is a ptrace buffer; we put in only user xstates: 1003 */ 1004 memset(&header, 0, sizeof(header)); 1005 header.xfeatures = xsave->header.xfeatures; 1006 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1007 1008 /* 1009 * Copy xregs_state->header: 1010 */ 1011 offset = offsetof(struct xregs_state, header); 1012 size = sizeof(header); 1013 1014 __copy_xstate_to_kernel(kbuf, &header, offset, size, size_total); 1015 1016 for (i = 0; i < XFEATURE_MAX; i++) { 1017 /* 1018 * Copy only in-use xstates: 1019 */ 1020 if ((header.xfeatures >> i) & 1) { 1021 void *src = __raw_xsave_addr(xsave, 1 << i); 1022 1023 offset = xstate_offsets[i]; 1024 size = xstate_sizes[i]; 1025 1026 /* The next component has to fit fully into the output buffer: */ 1027 if (offset + size > size_total) 1028 break; 1029 1030 __copy_xstate_to_kernel(kbuf, src, offset, size, size_total); 1031 } 1032 1033 } 1034 1035 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1036 offset = offsetof(struct fxregs_state, mxcsr); 1037 size = MXCSR_AND_FLAGS_SIZE; 1038 __copy_xstate_to_kernel(kbuf, &xsave->i387.mxcsr, offset, size, size_total); 1039 } 1040 1041 /* 1042 * Fill xsave->i387.sw_reserved value for ptrace frame: 1043 */ 1044 offset = offsetof(struct fxregs_state, sw_reserved); 1045 size = sizeof(xstate_fx_sw_bytes); 1046 1047 __copy_xstate_to_kernel(kbuf, xstate_fx_sw_bytes, offset, size, size_total); 1048 1049 return 0; 1050 } 1051 1052 static inline int 1053 __copy_xstate_to_user(void __user *ubuf, const void *data, unsigned int offset, unsigned int size, unsigned int size_total) 1054 { 1055 if (!size) 1056 return 0; 1057 1058 if (offset < size_total) { 1059 unsigned int copy = min(size, size_total - offset); 1060 1061 if (__copy_to_user(ubuf + offset, data, copy)) 1062 return -EFAULT; 1063 } 1064 return 0; 1065 } 1066 1067 /* 1068 * Convert from kernel XSAVES compacted format to standard format and copy 1069 * to a user-space buffer. It supports partial copy but pos always starts from 1070 * zero. This is called from xstateregs_get() and there we check the CPU 1071 * has XSAVES. 1072 */ 1073 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset_start, unsigned int size_total) 1074 { 1075 unsigned int offset, size; 1076 int ret, i; 1077 struct xstate_header header; 1078 1079 /* 1080 * Currently copy_regset_to_user() starts from pos 0: 1081 */ 1082 if (unlikely(offset_start != 0)) 1083 return -EFAULT; 1084 1085 /* 1086 * The destination is a ptrace buffer; we put in only user xstates: 1087 */ 1088 memset(&header, 0, sizeof(header)); 1089 header.xfeatures = xsave->header.xfeatures; 1090 header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; 1091 1092 /* 1093 * Copy xregs_state->header: 1094 */ 1095 offset = offsetof(struct xregs_state, header); 1096 size = sizeof(header); 1097 1098 ret = __copy_xstate_to_user(ubuf, &header, offset, size, size_total); 1099 if (ret) 1100 return ret; 1101 1102 for (i = 0; i < XFEATURE_MAX; i++) { 1103 /* 1104 * Copy only in-use xstates: 1105 */ 1106 if ((header.xfeatures >> i) & 1) { 1107 void *src = __raw_xsave_addr(xsave, 1 << i); 1108 1109 offset = xstate_offsets[i]; 1110 size = xstate_sizes[i]; 1111 1112 /* The next component has to fit fully into the output buffer: */ 1113 if (offset + size > size_total) 1114 break; 1115 1116 ret = __copy_xstate_to_user(ubuf, src, offset, size, size_total); 1117 if (ret) 1118 return ret; 1119 } 1120 1121 } 1122 1123 if (xfeatures_mxcsr_quirk(header.xfeatures)) { 1124 offset = offsetof(struct fxregs_state, mxcsr); 1125 size = MXCSR_AND_FLAGS_SIZE; 1126 __copy_xstate_to_user(ubuf, &xsave->i387.mxcsr, offset, size, size_total); 1127 } 1128 1129 /* 1130 * Fill xsave->i387.sw_reserved value for ptrace frame: 1131 */ 1132 offset = offsetof(struct fxregs_state, sw_reserved); 1133 size = sizeof(xstate_fx_sw_bytes); 1134 1135 ret = __copy_xstate_to_user(ubuf, xstate_fx_sw_bytes, offset, size, size_total); 1136 if (ret) 1137 return ret; 1138 1139 return 0; 1140 } 1141 1142 /* 1143 * Convert from a ptrace standard-format kernel buffer to kernel XSAVES format 1144 * and copy to the target thread. This is called from xstateregs_set(). 1145 */ 1146 int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) 1147 { 1148 unsigned int offset, size; 1149 int i; 1150 struct xstate_header hdr; 1151 1152 offset = offsetof(struct xregs_state, header); 1153 size = sizeof(hdr); 1154 1155 memcpy(&hdr, kbuf + offset, size); 1156 1157 if (validate_xstate_header(&hdr)) 1158 return -EINVAL; 1159 1160 for (i = 0; i < XFEATURE_MAX; i++) { 1161 u64 mask = ((u64)1 << i); 1162 1163 if (hdr.xfeatures & mask) { 1164 void *dst = __raw_xsave_addr(xsave, 1 << i); 1165 1166 offset = xstate_offsets[i]; 1167 size = xstate_sizes[i]; 1168 1169 memcpy(dst, kbuf + offset, size); 1170 } 1171 } 1172 1173 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1174 offset = offsetof(struct fxregs_state, mxcsr); 1175 size = MXCSR_AND_FLAGS_SIZE; 1176 memcpy(&xsave->i387.mxcsr, kbuf + offset, size); 1177 } 1178 1179 /* 1180 * The state that came in from userspace was user-state only. 1181 * Mask all the user states out of 'xfeatures': 1182 */ 1183 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1184 1185 /* 1186 * Add back in the features that came in from userspace: 1187 */ 1188 xsave->header.xfeatures |= hdr.xfeatures; 1189 1190 return 0; 1191 } 1192 1193 /* 1194 * Convert from a ptrace or sigreturn standard-format user-space buffer to 1195 * kernel XSAVES format and copy to the target thread. This is called from 1196 * xstateregs_set(), as well as potentially from the sigreturn() and 1197 * rt_sigreturn() system calls. 1198 */ 1199 int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) 1200 { 1201 unsigned int offset, size; 1202 int i; 1203 struct xstate_header hdr; 1204 1205 offset = offsetof(struct xregs_state, header); 1206 size = sizeof(hdr); 1207 1208 if (__copy_from_user(&hdr, ubuf + offset, size)) 1209 return -EFAULT; 1210 1211 if (validate_xstate_header(&hdr)) 1212 return -EINVAL; 1213 1214 for (i = 0; i < XFEATURE_MAX; i++) { 1215 u64 mask = ((u64)1 << i); 1216 1217 if (hdr.xfeatures & mask) { 1218 void *dst = __raw_xsave_addr(xsave, 1 << i); 1219 1220 offset = xstate_offsets[i]; 1221 size = xstate_sizes[i]; 1222 1223 if (__copy_from_user(dst, ubuf + offset, size)) 1224 return -EFAULT; 1225 } 1226 } 1227 1228 if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { 1229 offset = offsetof(struct fxregs_state, mxcsr); 1230 size = MXCSR_AND_FLAGS_SIZE; 1231 if (__copy_from_user(&xsave->i387.mxcsr, ubuf + offset, size)) 1232 return -EFAULT; 1233 } 1234 1235 /* 1236 * The state that came in from userspace was user-state only. 1237 * Mask all the user states out of 'xfeatures': 1238 */ 1239 xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; 1240 1241 /* 1242 * Add back in the features that came in from userspace: 1243 */ 1244 xsave->header.xfeatures |= hdr.xfeatures; 1245 1246 return 0; 1247 } 1248