1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Based on arch/arm/kernel/signal.c 4 * 5 * Copyright (C) 1995-2009 Russell King 6 * Copyright (C) 2012 ARM Ltd. 7 */ 8 9 #include <linux/cache.h> 10 #include <linux/compat.h> 11 #include <linux/errno.h> 12 #include <linux/kernel.h> 13 #include <linux/signal.h> 14 #include <linux/freezer.h> 15 #include <linux/stddef.h> 16 #include <linux/uaccess.h> 17 #include <linux/sizes.h> 18 #include <linux/string.h> 19 #include <linux/resume_user_mode.h> 20 #include <linux/ratelimit.h> 21 #include <linux/syscalls.h> 22 23 #include <asm/daifflags.h> 24 #include <asm/debug-monitors.h> 25 #include <asm/elf.h> 26 #include <asm/cacheflush.h> 27 #include <asm/ucontext.h> 28 #include <asm/unistd.h> 29 #include <asm/fpsimd.h> 30 #include <asm/ptrace.h> 31 #include <asm/syscall.h> 32 #include <asm/signal32.h> 33 #include <asm/traps.h> 34 #include <asm/vdso.h> 35 36 /* 37 * Do a signal return; undo the signal stack. These are aligned to 128-bit. 38 */ 39 struct rt_sigframe { 40 struct siginfo info; 41 struct ucontext uc; 42 }; 43 44 struct frame_record { 45 u64 fp; 46 u64 lr; 47 }; 48 49 struct rt_sigframe_user_layout { 50 struct rt_sigframe __user *sigframe; 51 struct frame_record __user *next_frame; 52 53 unsigned long size; /* size of allocated sigframe data */ 54 unsigned long limit; /* largest allowed size */ 55 56 unsigned long fpsimd_offset; 57 unsigned long esr_offset; 58 unsigned long sve_offset; 59 unsigned long za_offset; 60 unsigned long extra_offset; 61 unsigned long end_offset; 62 }; 63 64 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16) 65 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16) 66 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16) 67 68 static void init_user_layout(struct rt_sigframe_user_layout *user) 69 { 70 const size_t reserved_size = 71 sizeof(user->sigframe->uc.uc_mcontext.__reserved); 72 73 memset(user, 0, sizeof(*user)); 74 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved); 75 76 user->limit = user->size + reserved_size; 77 78 user->limit -= TERMINATOR_SIZE; 79 user->limit -= EXTRA_CONTEXT_SIZE; 80 /* Reserve space for extension and terminator ^ */ 81 } 82 83 static size_t sigframe_size(struct rt_sigframe_user_layout const *user) 84 { 85 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16); 86 } 87 88 /* 89 * Sanity limit on the approximate maximum size of signal frame we'll 90 * try to generate. Stack alignment padding and the frame record are 91 * not taken into account. This limit is not a guarantee and is 92 * NOT ABI. 93 */ 94 #define SIGFRAME_MAXSZ SZ_64K 95 96 static int __sigframe_alloc(struct rt_sigframe_user_layout *user, 97 unsigned long *offset, size_t size, bool extend) 98 { 99 size_t padded_size = round_up(size, 16); 100 101 if (padded_size > user->limit - user->size && 102 !user->extra_offset && 103 extend) { 104 int ret; 105 106 user->limit += EXTRA_CONTEXT_SIZE; 107 ret = __sigframe_alloc(user, &user->extra_offset, 108 sizeof(struct extra_context), false); 109 if (ret) { 110 user->limit -= EXTRA_CONTEXT_SIZE; 111 return ret; 112 } 113 114 /* Reserve space for the __reserved[] terminator */ 115 user->size += TERMINATOR_SIZE; 116 117 /* 118 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for 119 * the terminator: 120 */ 121 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE; 122 } 123 124 /* Still not enough space? Bad luck! */ 125 if (padded_size > user->limit - user->size) 126 return -ENOMEM; 127 128 *offset = user->size; 129 user->size += padded_size; 130 131 return 0; 132 } 133 134 /* 135 * Allocate space for an optional record of <size> bytes in the user 136 * signal frame. The offset from the signal frame base address to the 137 * allocated block is assigned to *offset. 138 */ 139 static int sigframe_alloc(struct rt_sigframe_user_layout *user, 140 unsigned long *offset, size_t size) 141 { 142 return __sigframe_alloc(user, offset, size, true); 143 } 144 145 /* Allocate the null terminator record and prevent further allocations */ 146 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user) 147 { 148 int ret; 149 150 /* Un-reserve the space reserved for the terminator: */ 151 user->limit += TERMINATOR_SIZE; 152 153 ret = sigframe_alloc(user, &user->end_offset, 154 sizeof(struct _aarch64_ctx)); 155 if (ret) 156 return ret; 157 158 /* Prevent further allocation: */ 159 user->limit = user->size; 160 return 0; 161 } 162 163 static void __user *apply_user_offset( 164 struct rt_sigframe_user_layout const *user, unsigned long offset) 165 { 166 char __user *base = (char __user *)user->sigframe; 167 168 return base + offset; 169 } 170 171 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) 172 { 173 struct user_fpsimd_state const *fpsimd = 174 ¤t->thread.uw.fpsimd_state; 175 int err; 176 177 /* copy the FP and status/control registers */ 178 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); 179 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err); 180 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err); 181 182 /* copy the magic/size information */ 183 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err); 184 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err); 185 186 return err ? -EFAULT : 0; 187 } 188 189 static int restore_fpsimd_context(struct fpsimd_context __user *ctx) 190 { 191 struct user_fpsimd_state fpsimd; 192 __u32 magic, size; 193 int err = 0; 194 195 /* check the magic/size information */ 196 __get_user_error(magic, &ctx->head.magic, err); 197 __get_user_error(size, &ctx->head.size, err); 198 if (err) 199 return -EFAULT; 200 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context)) 201 return -EINVAL; 202 203 /* copy the FP and status/control registers */ 204 err = __copy_from_user(fpsimd.vregs, ctx->vregs, 205 sizeof(fpsimd.vregs)); 206 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err); 207 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); 208 209 clear_thread_flag(TIF_SVE); 210 211 /* load the hardware registers from the fpsimd_state structure */ 212 if (!err) 213 fpsimd_update_current_state(&fpsimd); 214 215 return err ? -EFAULT : 0; 216 } 217 218 219 struct user_ctxs { 220 struct fpsimd_context __user *fpsimd; 221 struct sve_context __user *sve; 222 struct za_context __user *za; 223 }; 224 225 #ifdef CONFIG_ARM64_SVE 226 227 static int preserve_sve_context(struct sve_context __user *ctx) 228 { 229 int err = 0; 230 u16 reserved[ARRAY_SIZE(ctx->__reserved)]; 231 u16 flags = 0; 232 unsigned int vl = task_get_sve_vl(current); 233 unsigned int vq = 0; 234 235 if (thread_sm_enabled(¤t->thread)) { 236 vl = task_get_sme_vl(current); 237 vq = sve_vq_from_vl(vl); 238 flags |= SVE_SIG_FLAG_SM; 239 } else if (test_thread_flag(TIF_SVE)) { 240 vq = sve_vq_from_vl(vl); 241 } 242 243 memset(reserved, 0, sizeof(reserved)); 244 245 __put_user_error(SVE_MAGIC, &ctx->head.magic, err); 246 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16), 247 &ctx->head.size, err); 248 __put_user_error(vl, &ctx->vl, err); 249 __put_user_error(flags, &ctx->flags, err); 250 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); 251 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); 252 253 if (vq) { 254 /* 255 * This assumes that the SVE state has already been saved to 256 * the task struct by calling the function 257 * fpsimd_signal_preserve_current_state(). 258 */ 259 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET, 260 current->thread.sve_state, 261 SVE_SIG_REGS_SIZE(vq)); 262 } 263 264 return err ? -EFAULT : 0; 265 } 266 267 static int restore_sve_fpsimd_context(struct user_ctxs *user) 268 { 269 int err; 270 unsigned int vl, vq; 271 struct user_fpsimd_state fpsimd; 272 struct sve_context sve; 273 274 if (__copy_from_user(&sve, user->sve, sizeof(sve))) 275 return -EFAULT; 276 277 if (sve.flags & SVE_SIG_FLAG_SM) { 278 if (!system_supports_sme()) 279 return -EINVAL; 280 281 vl = task_get_sme_vl(current); 282 } else { 283 vl = task_get_sve_vl(current); 284 } 285 286 if (sve.vl != vl) 287 return -EINVAL; 288 289 if (sve.head.size <= sizeof(*user->sve)) { 290 clear_thread_flag(TIF_SVE); 291 current->thread.svcr &= ~SVCR_SM_MASK; 292 goto fpsimd_only; 293 } 294 295 vq = sve_vq_from_vl(sve.vl); 296 297 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq)) 298 return -EINVAL; 299 300 /* 301 * Careful: we are about __copy_from_user() directly into 302 * thread.sve_state with preemption enabled, so protection is 303 * needed to prevent a racing context switch from writing stale 304 * registers back over the new data. 305 */ 306 307 fpsimd_flush_task_state(current); 308 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ 309 310 sve_alloc(current); 311 if (!current->thread.sve_state) { 312 clear_thread_flag(TIF_SVE); 313 return -ENOMEM; 314 } 315 316 err = __copy_from_user(current->thread.sve_state, 317 (char __user const *)user->sve + 318 SVE_SIG_REGS_OFFSET, 319 SVE_SIG_REGS_SIZE(vq)); 320 if (err) 321 return -EFAULT; 322 323 if (sve.flags & SVE_SIG_FLAG_SM) 324 current->thread.svcr |= SVCR_SM_MASK; 325 else 326 set_thread_flag(TIF_SVE); 327 328 fpsimd_only: 329 /* copy the FP and status/control registers */ 330 /* restore_sigframe() already checked that user->fpsimd != NULL. */ 331 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs, 332 sizeof(fpsimd.vregs)); 333 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err); 334 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err); 335 336 /* load the hardware registers from the fpsimd_state structure */ 337 if (!err) 338 fpsimd_update_current_state(&fpsimd); 339 340 return err ? -EFAULT : 0; 341 } 342 343 #else /* ! CONFIG_ARM64_SVE */ 344 345 /* Turn any non-optimised out attempts to use these into a link error: */ 346 extern int preserve_sve_context(void __user *ctx); 347 extern int restore_sve_fpsimd_context(struct user_ctxs *user); 348 349 #endif /* ! CONFIG_ARM64_SVE */ 350 351 #ifdef CONFIG_ARM64_SME 352 353 static int preserve_za_context(struct za_context __user *ctx) 354 { 355 int err = 0; 356 u16 reserved[ARRAY_SIZE(ctx->__reserved)]; 357 unsigned int vl = task_get_sme_vl(current); 358 unsigned int vq; 359 360 if (thread_za_enabled(¤t->thread)) 361 vq = sve_vq_from_vl(vl); 362 else 363 vq = 0; 364 365 memset(reserved, 0, sizeof(reserved)); 366 367 __put_user_error(ZA_MAGIC, &ctx->head.magic, err); 368 __put_user_error(round_up(ZA_SIG_CONTEXT_SIZE(vq), 16), 369 &ctx->head.size, err); 370 __put_user_error(vl, &ctx->vl, err); 371 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); 372 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); 373 374 if (vq) { 375 /* 376 * This assumes that the ZA state has already been saved to 377 * the task struct by calling the function 378 * fpsimd_signal_preserve_current_state(). 379 */ 380 err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET, 381 current->thread.za_state, 382 ZA_SIG_REGS_SIZE(vq)); 383 } 384 385 return err ? -EFAULT : 0; 386 } 387 388 static int restore_za_context(struct user_ctxs *user) 389 { 390 int err; 391 unsigned int vq; 392 struct za_context za; 393 394 if (__copy_from_user(&za, user->za, sizeof(za))) 395 return -EFAULT; 396 397 if (za.vl != task_get_sme_vl(current)) 398 return -EINVAL; 399 400 if (za.head.size <= sizeof(*user->za)) { 401 current->thread.svcr &= ~SVCR_ZA_MASK; 402 return 0; 403 } 404 405 vq = sve_vq_from_vl(za.vl); 406 407 if (za.head.size < ZA_SIG_CONTEXT_SIZE(vq)) 408 return -EINVAL; 409 410 /* 411 * Careful: we are about __copy_from_user() directly into 412 * thread.za_state with preemption enabled, so protection is 413 * needed to prevent a racing context switch from writing stale 414 * registers back over the new data. 415 */ 416 417 fpsimd_flush_task_state(current); 418 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ 419 420 sme_alloc(current); 421 if (!current->thread.za_state) { 422 current->thread.svcr &= ~SVCR_ZA_MASK; 423 clear_thread_flag(TIF_SME); 424 return -ENOMEM; 425 } 426 427 err = __copy_from_user(current->thread.za_state, 428 (char __user const *)user->za + 429 ZA_SIG_REGS_OFFSET, 430 ZA_SIG_REGS_SIZE(vq)); 431 if (err) 432 return -EFAULT; 433 434 set_thread_flag(TIF_SME); 435 current->thread.svcr |= SVCR_ZA_MASK; 436 437 return 0; 438 } 439 #else /* ! CONFIG_ARM64_SME */ 440 441 /* Turn any non-optimised out attempts to use these into a link error: */ 442 extern int preserve_za_context(void __user *ctx); 443 extern int restore_za_context(struct user_ctxs *user); 444 445 #endif /* ! CONFIG_ARM64_SME */ 446 447 static int parse_user_sigframe(struct user_ctxs *user, 448 struct rt_sigframe __user *sf) 449 { 450 struct sigcontext __user *const sc = &sf->uc.uc_mcontext; 451 struct _aarch64_ctx __user *head; 452 char __user *base = (char __user *)&sc->__reserved; 453 size_t offset = 0; 454 size_t limit = sizeof(sc->__reserved); 455 bool have_extra_context = false; 456 char const __user *const sfp = (char const __user *)sf; 457 458 user->fpsimd = NULL; 459 user->sve = NULL; 460 user->za = NULL; 461 462 if (!IS_ALIGNED((unsigned long)base, 16)) 463 goto invalid; 464 465 while (1) { 466 int err = 0; 467 u32 magic, size; 468 char const __user *userp; 469 struct extra_context const __user *extra; 470 u64 extra_datap; 471 u32 extra_size; 472 struct _aarch64_ctx const __user *end; 473 u32 end_magic, end_size; 474 475 if (limit - offset < sizeof(*head)) 476 goto invalid; 477 478 if (!IS_ALIGNED(offset, 16)) 479 goto invalid; 480 481 head = (struct _aarch64_ctx __user *)(base + offset); 482 __get_user_error(magic, &head->magic, err); 483 __get_user_error(size, &head->size, err); 484 if (err) 485 return err; 486 487 if (limit - offset < size) 488 goto invalid; 489 490 switch (magic) { 491 case 0: 492 if (size) 493 goto invalid; 494 495 goto done; 496 497 case FPSIMD_MAGIC: 498 if (!system_supports_fpsimd()) 499 goto invalid; 500 if (user->fpsimd) 501 goto invalid; 502 503 if (size < sizeof(*user->fpsimd)) 504 goto invalid; 505 506 user->fpsimd = (struct fpsimd_context __user *)head; 507 break; 508 509 case ESR_MAGIC: 510 /* ignore */ 511 break; 512 513 case SVE_MAGIC: 514 if (!system_supports_sve() && !system_supports_sme()) 515 goto invalid; 516 517 if (user->sve) 518 goto invalid; 519 520 if (size < sizeof(*user->sve)) 521 goto invalid; 522 523 user->sve = (struct sve_context __user *)head; 524 break; 525 526 case ZA_MAGIC: 527 if (!system_supports_sme()) 528 goto invalid; 529 530 if (user->za) 531 goto invalid; 532 533 if (size < sizeof(*user->za)) 534 goto invalid; 535 536 user->za = (struct za_context __user *)head; 537 break; 538 539 case EXTRA_MAGIC: 540 if (have_extra_context) 541 goto invalid; 542 543 if (size < sizeof(*extra)) 544 goto invalid; 545 546 userp = (char const __user *)head; 547 548 extra = (struct extra_context const __user *)userp; 549 userp += size; 550 551 __get_user_error(extra_datap, &extra->datap, err); 552 __get_user_error(extra_size, &extra->size, err); 553 if (err) 554 return err; 555 556 /* Check for the dummy terminator in __reserved[]: */ 557 558 if (limit - offset - size < TERMINATOR_SIZE) 559 goto invalid; 560 561 end = (struct _aarch64_ctx const __user *)userp; 562 userp += TERMINATOR_SIZE; 563 564 __get_user_error(end_magic, &end->magic, err); 565 __get_user_error(end_size, &end->size, err); 566 if (err) 567 return err; 568 569 if (end_magic || end_size) 570 goto invalid; 571 572 /* Prevent looping/repeated parsing of extra_context */ 573 have_extra_context = true; 574 575 base = (__force void __user *)extra_datap; 576 if (!IS_ALIGNED((unsigned long)base, 16)) 577 goto invalid; 578 579 if (!IS_ALIGNED(extra_size, 16)) 580 goto invalid; 581 582 if (base != userp) 583 goto invalid; 584 585 /* Reject "unreasonably large" frames: */ 586 if (extra_size > sfp + SIGFRAME_MAXSZ - userp) 587 goto invalid; 588 589 /* 590 * Ignore trailing terminator in __reserved[] 591 * and start parsing extra data: 592 */ 593 offset = 0; 594 limit = extra_size; 595 596 if (!access_ok(base, limit)) 597 goto invalid; 598 599 continue; 600 601 default: 602 goto invalid; 603 } 604 605 if (size < sizeof(*head)) 606 goto invalid; 607 608 if (limit - offset < size) 609 goto invalid; 610 611 offset += size; 612 } 613 614 done: 615 return 0; 616 617 invalid: 618 return -EINVAL; 619 } 620 621 static int restore_sigframe(struct pt_regs *regs, 622 struct rt_sigframe __user *sf) 623 { 624 sigset_t set; 625 int i, err; 626 struct user_ctxs user; 627 628 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 629 if (err == 0) 630 set_current_blocked(&set); 631 632 for (i = 0; i < 31; i++) 633 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], 634 err); 635 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); 636 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); 637 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); 638 639 /* 640 * Avoid sys_rt_sigreturn() restarting. 641 */ 642 forget_syscall(regs); 643 644 err |= !valid_user_regs(®s->user_regs, current); 645 if (err == 0) 646 err = parse_user_sigframe(&user, sf); 647 648 if (err == 0 && system_supports_fpsimd()) { 649 if (!user.fpsimd) 650 return -EINVAL; 651 652 if (user.sve) { 653 if (!system_supports_sve()) 654 return -EINVAL; 655 656 err = restore_sve_fpsimd_context(&user); 657 } else { 658 err = restore_fpsimd_context(user.fpsimd); 659 } 660 } 661 662 if (err == 0 && system_supports_sme() && user.za) 663 err = restore_za_context(&user); 664 665 return err; 666 } 667 668 SYSCALL_DEFINE0(rt_sigreturn) 669 { 670 struct pt_regs *regs = current_pt_regs(); 671 struct rt_sigframe __user *frame; 672 673 /* Always make any pending restarted system calls return -EINTR */ 674 current->restart_block.fn = do_no_restart_syscall; 675 676 /* 677 * Since we stacked the signal on a 128-bit boundary, then 'sp' should 678 * be word aligned here. 679 */ 680 if (regs->sp & 15) 681 goto badframe; 682 683 frame = (struct rt_sigframe __user *)regs->sp; 684 685 if (!access_ok(frame, sizeof (*frame))) 686 goto badframe; 687 688 if (restore_sigframe(regs, frame)) 689 goto badframe; 690 691 if (restore_altstack(&frame->uc.uc_stack)) 692 goto badframe; 693 694 return regs->regs[0]; 695 696 badframe: 697 arm64_notify_segfault(regs->sp); 698 return 0; 699 } 700 701 /* 702 * Determine the layout of optional records in the signal frame 703 * 704 * add_all: if true, lays out the biggest possible signal frame for 705 * this task; otherwise, generates a layout for the current state 706 * of the task. 707 */ 708 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, 709 bool add_all) 710 { 711 int err; 712 713 if (system_supports_fpsimd()) { 714 err = sigframe_alloc(user, &user->fpsimd_offset, 715 sizeof(struct fpsimd_context)); 716 if (err) 717 return err; 718 } 719 720 /* fault information, if valid */ 721 if (add_all || current->thread.fault_code) { 722 err = sigframe_alloc(user, &user->esr_offset, 723 sizeof(struct esr_context)); 724 if (err) 725 return err; 726 } 727 728 if (system_supports_sve()) { 729 unsigned int vq = 0; 730 731 if (add_all || test_thread_flag(TIF_SVE) || 732 thread_sm_enabled(¤t->thread)) { 733 int vl = max(sve_max_vl(), sme_max_vl()); 734 735 if (!add_all) 736 vl = thread_get_cur_vl(¤t->thread); 737 738 vq = sve_vq_from_vl(vl); 739 } 740 741 err = sigframe_alloc(user, &user->sve_offset, 742 SVE_SIG_CONTEXT_SIZE(vq)); 743 if (err) 744 return err; 745 } 746 747 if (system_supports_sme()) { 748 unsigned int vl; 749 unsigned int vq = 0; 750 751 if (add_all) 752 vl = sme_max_vl(); 753 else 754 vl = task_get_sme_vl(current); 755 756 if (thread_za_enabled(¤t->thread)) 757 vq = sve_vq_from_vl(vl); 758 759 err = sigframe_alloc(user, &user->za_offset, 760 ZA_SIG_CONTEXT_SIZE(vq)); 761 if (err) 762 return err; 763 } 764 765 return sigframe_alloc_end(user); 766 } 767 768 static int setup_sigframe(struct rt_sigframe_user_layout *user, 769 struct pt_regs *regs, sigset_t *set) 770 { 771 int i, err = 0; 772 struct rt_sigframe __user *sf = user->sigframe; 773 774 /* set up the stack frame for unwinding */ 775 __put_user_error(regs->regs[29], &user->next_frame->fp, err); 776 __put_user_error(regs->regs[30], &user->next_frame->lr, err); 777 778 for (i = 0; i < 31; i++) 779 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], 780 err); 781 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); 782 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); 783 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); 784 785 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); 786 787 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 788 789 if (err == 0 && system_supports_fpsimd()) { 790 struct fpsimd_context __user *fpsimd_ctx = 791 apply_user_offset(user, user->fpsimd_offset); 792 err |= preserve_fpsimd_context(fpsimd_ctx); 793 } 794 795 /* fault information, if valid */ 796 if (err == 0 && user->esr_offset) { 797 struct esr_context __user *esr_ctx = 798 apply_user_offset(user, user->esr_offset); 799 800 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err); 801 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err); 802 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err); 803 } 804 805 /* Scalable Vector Extension state (including streaming), if present */ 806 if ((system_supports_sve() || system_supports_sme()) && 807 err == 0 && user->sve_offset) { 808 struct sve_context __user *sve_ctx = 809 apply_user_offset(user, user->sve_offset); 810 err |= preserve_sve_context(sve_ctx); 811 } 812 813 /* ZA state if present */ 814 if (system_supports_sme() && err == 0 && user->za_offset) { 815 struct za_context __user *za_ctx = 816 apply_user_offset(user, user->za_offset); 817 err |= preserve_za_context(za_ctx); 818 } 819 820 if (err == 0 && user->extra_offset) { 821 char __user *sfp = (char __user *)user->sigframe; 822 char __user *userp = 823 apply_user_offset(user, user->extra_offset); 824 825 struct extra_context __user *extra; 826 struct _aarch64_ctx __user *end; 827 u64 extra_datap; 828 u32 extra_size; 829 830 extra = (struct extra_context __user *)userp; 831 userp += EXTRA_CONTEXT_SIZE; 832 833 end = (struct _aarch64_ctx __user *)userp; 834 userp += TERMINATOR_SIZE; 835 836 /* 837 * extra_datap is just written to the signal frame. 838 * The value gets cast back to a void __user * 839 * during sigreturn. 840 */ 841 extra_datap = (__force u64)userp; 842 extra_size = sfp + round_up(user->size, 16) - userp; 843 844 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err); 845 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err); 846 __put_user_error(extra_datap, &extra->datap, err); 847 __put_user_error(extra_size, &extra->size, err); 848 849 /* Add the terminator */ 850 __put_user_error(0, &end->magic, err); 851 __put_user_error(0, &end->size, err); 852 } 853 854 /* set the "end" magic */ 855 if (err == 0) { 856 struct _aarch64_ctx __user *end = 857 apply_user_offset(user, user->end_offset); 858 859 __put_user_error(0, &end->magic, err); 860 __put_user_error(0, &end->size, err); 861 } 862 863 return err; 864 } 865 866 static int get_sigframe(struct rt_sigframe_user_layout *user, 867 struct ksignal *ksig, struct pt_regs *regs) 868 { 869 unsigned long sp, sp_top; 870 int err; 871 872 init_user_layout(user); 873 err = setup_sigframe_layout(user, false); 874 if (err) 875 return err; 876 877 sp = sp_top = sigsp(regs->sp, ksig); 878 879 sp = round_down(sp - sizeof(struct frame_record), 16); 880 user->next_frame = (struct frame_record __user *)sp; 881 882 sp = round_down(sp, 16) - sigframe_size(user); 883 user->sigframe = (struct rt_sigframe __user *)sp; 884 885 /* 886 * Check that we can actually write to the signal frame. 887 */ 888 if (!access_ok(user->sigframe, sp_top - sp)) 889 return -EFAULT; 890 891 return 0; 892 } 893 894 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka, 895 struct rt_sigframe_user_layout *user, int usig) 896 { 897 __sigrestore_t sigtramp; 898 899 regs->regs[0] = usig; 900 regs->sp = (unsigned long)user->sigframe; 901 regs->regs[29] = (unsigned long)&user->next_frame->fp; 902 regs->pc = (unsigned long)ka->sa.sa_handler; 903 904 /* 905 * Signal delivery is a (wacky) indirect function call in 906 * userspace, so simulate the same setting of BTYPE as a BLR 907 * <register containing the signal handler entry point>. 908 * Signal delivery to a location in a PROT_BTI guarded page 909 * that is not a function entry point will now trigger a 910 * SIGILL in userspace. 911 * 912 * If the signal handler entry point is not in a PROT_BTI 913 * guarded page, this is harmless. 914 */ 915 if (system_supports_bti()) { 916 regs->pstate &= ~PSR_BTYPE_MASK; 917 regs->pstate |= PSR_BTYPE_C; 918 } 919 920 /* TCO (Tag Check Override) always cleared for signal handlers */ 921 regs->pstate &= ~PSR_TCO_BIT; 922 923 /* Signal handlers are invoked with ZA and streaming mode disabled */ 924 if (system_supports_sme()) { 925 current->thread.svcr &= ~(SVCR_ZA_MASK | 926 SVCR_SM_MASK); 927 sme_smstop(); 928 } 929 930 if (ka->sa.sa_flags & SA_RESTORER) 931 sigtramp = ka->sa.sa_restorer; 932 else 933 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp); 934 935 regs->regs[30] = (unsigned long)sigtramp; 936 } 937 938 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set, 939 struct pt_regs *regs) 940 { 941 struct rt_sigframe_user_layout user; 942 struct rt_sigframe __user *frame; 943 int err = 0; 944 945 fpsimd_signal_preserve_current_state(); 946 947 if (get_sigframe(&user, ksig, regs)) 948 return 1; 949 950 frame = user.sigframe; 951 952 __put_user_error(0, &frame->uc.uc_flags, err); 953 __put_user_error(NULL, &frame->uc.uc_link, err); 954 955 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 956 err |= setup_sigframe(&user, regs, set); 957 if (err == 0) { 958 setup_return(regs, &ksig->ka, &user, usig); 959 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 960 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 961 regs->regs[1] = (unsigned long)&frame->info; 962 regs->regs[2] = (unsigned long)&frame->uc; 963 } 964 } 965 966 return err; 967 } 968 969 static void setup_restart_syscall(struct pt_regs *regs) 970 { 971 if (is_compat_task()) 972 compat_setup_restart_syscall(regs); 973 else 974 regs->regs[8] = __NR_restart_syscall; 975 } 976 977 /* 978 * OK, we're invoking a handler 979 */ 980 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 981 { 982 sigset_t *oldset = sigmask_to_save(); 983 int usig = ksig->sig; 984 int ret; 985 986 rseq_signal_deliver(ksig, regs); 987 988 /* 989 * Set up the stack frame 990 */ 991 if (is_compat_task()) { 992 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 993 ret = compat_setup_rt_frame(usig, ksig, oldset, regs); 994 else 995 ret = compat_setup_frame(usig, ksig, oldset, regs); 996 } else { 997 ret = setup_rt_frame(usig, ksig, oldset, regs); 998 } 999 1000 /* 1001 * Check that the resulting registers are actually sane. 1002 */ 1003 ret |= !valid_user_regs(®s->user_regs, current); 1004 1005 /* Step into the signal handler if we are stepping */ 1006 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); 1007 } 1008 1009 /* 1010 * Note that 'init' is a special process: it doesn't get signals it doesn't 1011 * want to handle. Thus you cannot kill init even with a SIGKILL even by 1012 * mistake. 1013 * 1014 * Note that we go through the signals twice: once to check the signals that 1015 * the kernel can handle, and then we build all the user-level signal handling 1016 * stack-frames in one go after that. 1017 */ 1018 static void do_signal(struct pt_regs *regs) 1019 { 1020 unsigned long continue_addr = 0, restart_addr = 0; 1021 int retval = 0; 1022 struct ksignal ksig; 1023 bool syscall = in_syscall(regs); 1024 1025 /* 1026 * If we were from a system call, check for system call restarting... 1027 */ 1028 if (syscall) { 1029 continue_addr = regs->pc; 1030 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4); 1031 retval = regs->regs[0]; 1032 1033 /* 1034 * Avoid additional syscall restarting via ret_to_user. 1035 */ 1036 forget_syscall(regs); 1037 1038 /* 1039 * Prepare for system call restart. We do this here so that a 1040 * debugger will see the already changed PC. 1041 */ 1042 switch (retval) { 1043 case -ERESTARTNOHAND: 1044 case -ERESTARTSYS: 1045 case -ERESTARTNOINTR: 1046 case -ERESTART_RESTARTBLOCK: 1047 regs->regs[0] = regs->orig_x0; 1048 regs->pc = restart_addr; 1049 break; 1050 } 1051 } 1052 1053 /* 1054 * Get the signal to deliver. When running under ptrace, at this point 1055 * the debugger may change all of our registers. 1056 */ 1057 if (get_signal(&ksig)) { 1058 /* 1059 * Depending on the signal settings, we may need to revert the 1060 * decision to restart the system call, but skip this if a 1061 * debugger has chosen to restart at a different PC. 1062 */ 1063 if (regs->pc == restart_addr && 1064 (retval == -ERESTARTNOHAND || 1065 retval == -ERESTART_RESTARTBLOCK || 1066 (retval == -ERESTARTSYS && 1067 !(ksig.ka.sa.sa_flags & SA_RESTART)))) { 1068 syscall_set_return_value(current, regs, -EINTR, 0); 1069 regs->pc = continue_addr; 1070 } 1071 1072 handle_signal(&ksig, regs); 1073 return; 1074 } 1075 1076 /* 1077 * Handle restarting a different system call. As above, if a debugger 1078 * has chosen to restart at a different PC, ignore the restart. 1079 */ 1080 if (syscall && regs->pc == restart_addr) { 1081 if (retval == -ERESTART_RESTARTBLOCK) 1082 setup_restart_syscall(regs); 1083 user_rewind_single_step(current); 1084 } 1085 1086 restore_saved_sigmask(); 1087 } 1088 1089 void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) 1090 { 1091 do { 1092 if (thread_flags & _TIF_NEED_RESCHED) { 1093 /* Unmask Debug and SError for the next task */ 1094 local_daif_restore(DAIF_PROCCTX_NOIRQ); 1095 1096 schedule(); 1097 } else { 1098 local_daif_restore(DAIF_PROCCTX); 1099 1100 if (thread_flags & _TIF_UPROBE) 1101 uprobe_notify_resume(regs); 1102 1103 if (thread_flags & _TIF_MTE_ASYNC_FAULT) { 1104 clear_thread_flag(TIF_MTE_ASYNC_FAULT); 1105 send_sig_fault(SIGSEGV, SEGV_MTEAERR, 1106 (void __user *)NULL, current); 1107 } 1108 1109 if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) 1110 do_signal(regs); 1111 1112 if (thread_flags & _TIF_NOTIFY_RESUME) 1113 resume_user_mode_work(regs); 1114 1115 if (thread_flags & _TIF_FOREIGN_FPSTATE) 1116 fpsimd_restore_current_state(); 1117 } 1118 1119 local_daif_mask(); 1120 thread_flags = read_thread_flags(); 1121 } while (thread_flags & _TIF_WORK_MASK); 1122 } 1123 1124 unsigned long __ro_after_init signal_minsigstksz; 1125 1126 /* 1127 * Determine the stack space required for guaranteed signal devliery. 1128 * This function is used to populate AT_MINSIGSTKSZ at process startup. 1129 * cpufeatures setup is assumed to be complete. 1130 */ 1131 void __init minsigstksz_setup(void) 1132 { 1133 struct rt_sigframe_user_layout user; 1134 1135 init_user_layout(&user); 1136 1137 /* 1138 * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't 1139 * be big enough, but it's our best guess: 1140 */ 1141 if (WARN_ON(setup_sigframe_layout(&user, true))) 1142 return; 1143 1144 signal_minsigstksz = sigframe_size(&user) + 1145 round_up(sizeof(struct frame_record), 16) + 1146 16; /* max alignment padding */ 1147 } 1148 1149 /* 1150 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as 1151 * changes likely come with new fields that should be added below. 1152 */ 1153 static_assert(NSIGILL == 11); 1154 static_assert(NSIGFPE == 15); 1155 static_assert(NSIGSEGV == 9); 1156 static_assert(NSIGBUS == 5); 1157 static_assert(NSIGTRAP == 6); 1158 static_assert(NSIGCHLD == 6); 1159 static_assert(NSIGSYS == 2); 1160 static_assert(sizeof(siginfo_t) == 128); 1161 static_assert(__alignof__(siginfo_t) == 8); 1162 static_assert(offsetof(siginfo_t, si_signo) == 0x00); 1163 static_assert(offsetof(siginfo_t, si_errno) == 0x04); 1164 static_assert(offsetof(siginfo_t, si_code) == 0x08); 1165 static_assert(offsetof(siginfo_t, si_pid) == 0x10); 1166 static_assert(offsetof(siginfo_t, si_uid) == 0x14); 1167 static_assert(offsetof(siginfo_t, si_tid) == 0x10); 1168 static_assert(offsetof(siginfo_t, si_overrun) == 0x14); 1169 static_assert(offsetof(siginfo_t, si_status) == 0x18); 1170 static_assert(offsetof(siginfo_t, si_utime) == 0x20); 1171 static_assert(offsetof(siginfo_t, si_stime) == 0x28); 1172 static_assert(offsetof(siginfo_t, si_value) == 0x18); 1173 static_assert(offsetof(siginfo_t, si_int) == 0x18); 1174 static_assert(offsetof(siginfo_t, si_ptr) == 0x18); 1175 static_assert(offsetof(siginfo_t, si_addr) == 0x10); 1176 static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18); 1177 static_assert(offsetof(siginfo_t, si_lower) == 0x20); 1178 static_assert(offsetof(siginfo_t, si_upper) == 0x28); 1179 static_assert(offsetof(siginfo_t, si_pkey) == 0x20); 1180 static_assert(offsetof(siginfo_t, si_perf_data) == 0x18); 1181 static_assert(offsetof(siginfo_t, si_perf_type) == 0x20); 1182 static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24); 1183 static_assert(offsetof(siginfo_t, si_band) == 0x10); 1184 static_assert(offsetof(siginfo_t, si_fd) == 0x18); 1185 static_assert(offsetof(siginfo_t, si_call_addr) == 0x10); 1186 static_assert(offsetof(siginfo_t, si_syscall) == 0x18); 1187 static_assert(offsetof(siginfo_t, si_arch) == 0x1c); 1188