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/personality.h> 15 #include <linux/freezer.h> 16 #include <linux/stddef.h> 17 #include <linux/uaccess.h> 18 #include <linux/sizes.h> 19 #include <linux/string.h> 20 #include <linux/tracehook.h> 21 #include <linux/ratelimit.h> 22 #include <linux/syscalls.h> 23 24 #include <asm/daifflags.h> 25 #include <asm/debug-monitors.h> 26 #include <asm/elf.h> 27 #include <asm/cacheflush.h> 28 #include <asm/ucontext.h> 29 #include <asm/unistd.h> 30 #include <asm/fpsimd.h> 31 #include <asm/ptrace.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 extra_offset; 60 unsigned long end_offset; 61 }; 62 63 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16) 64 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16) 65 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16) 66 67 static void init_user_layout(struct rt_sigframe_user_layout *user) 68 { 69 const size_t reserved_size = 70 sizeof(user->sigframe->uc.uc_mcontext.__reserved); 71 72 memset(user, 0, sizeof(*user)); 73 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved); 74 75 user->limit = user->size + reserved_size; 76 77 user->limit -= TERMINATOR_SIZE; 78 user->limit -= EXTRA_CONTEXT_SIZE; 79 /* Reserve space for extension and terminator ^ */ 80 } 81 82 static size_t sigframe_size(struct rt_sigframe_user_layout const *user) 83 { 84 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16); 85 } 86 87 /* 88 * Sanity limit on the approximate maximum size of signal frame we'll 89 * try to generate. Stack alignment padding and the frame record are 90 * not taken into account. This limit is not a guarantee and is 91 * NOT ABI. 92 */ 93 #define SIGFRAME_MAXSZ SZ_64K 94 95 static int __sigframe_alloc(struct rt_sigframe_user_layout *user, 96 unsigned long *offset, size_t size, bool extend) 97 { 98 size_t padded_size = round_up(size, 16); 99 100 if (padded_size > user->limit - user->size && 101 !user->extra_offset && 102 extend) { 103 int ret; 104 105 user->limit += EXTRA_CONTEXT_SIZE; 106 ret = __sigframe_alloc(user, &user->extra_offset, 107 sizeof(struct extra_context), false); 108 if (ret) { 109 user->limit -= EXTRA_CONTEXT_SIZE; 110 return ret; 111 } 112 113 /* Reserve space for the __reserved[] terminator */ 114 user->size += TERMINATOR_SIZE; 115 116 /* 117 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for 118 * the terminator: 119 */ 120 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE; 121 } 122 123 /* Still not enough space? Bad luck! */ 124 if (padded_size > user->limit - user->size) 125 return -ENOMEM; 126 127 *offset = user->size; 128 user->size += padded_size; 129 130 return 0; 131 } 132 133 /* 134 * Allocate space for an optional record of <size> bytes in the user 135 * signal frame. The offset from the signal frame base address to the 136 * allocated block is assigned to *offset. 137 */ 138 static int sigframe_alloc(struct rt_sigframe_user_layout *user, 139 unsigned long *offset, size_t size) 140 { 141 return __sigframe_alloc(user, offset, size, true); 142 } 143 144 /* Allocate the null terminator record and prevent further allocations */ 145 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user) 146 { 147 int ret; 148 149 /* Un-reserve the space reserved for the terminator: */ 150 user->limit += TERMINATOR_SIZE; 151 152 ret = sigframe_alloc(user, &user->end_offset, 153 sizeof(struct _aarch64_ctx)); 154 if (ret) 155 return ret; 156 157 /* Prevent further allocation: */ 158 user->limit = user->size; 159 return 0; 160 } 161 162 static void __user *apply_user_offset( 163 struct rt_sigframe_user_layout const *user, unsigned long offset) 164 { 165 char __user *base = (char __user *)user->sigframe; 166 167 return base + offset; 168 } 169 170 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) 171 { 172 struct user_fpsimd_state const *fpsimd = 173 ¤t->thread.uw.fpsimd_state; 174 int err; 175 176 /* copy the FP and status/control registers */ 177 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); 178 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err); 179 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err); 180 181 /* copy the magic/size information */ 182 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err); 183 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err); 184 185 return err ? -EFAULT : 0; 186 } 187 188 static int restore_fpsimd_context(struct fpsimd_context __user *ctx) 189 { 190 struct user_fpsimd_state fpsimd; 191 __u32 magic, size; 192 int err = 0; 193 194 /* check the magic/size information */ 195 __get_user_error(magic, &ctx->head.magic, err); 196 __get_user_error(size, &ctx->head.size, err); 197 if (err) 198 return -EFAULT; 199 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context)) 200 return -EINVAL; 201 202 /* copy the FP and status/control registers */ 203 err = __copy_from_user(fpsimd.vregs, ctx->vregs, 204 sizeof(fpsimd.vregs)); 205 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err); 206 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); 207 208 clear_thread_flag(TIF_SVE); 209 210 /* load the hardware registers from the fpsimd_state structure */ 211 if (!err) 212 fpsimd_update_current_state(&fpsimd); 213 214 return err ? -EFAULT : 0; 215 } 216 217 218 struct user_ctxs { 219 struct fpsimd_context __user *fpsimd; 220 struct sve_context __user *sve; 221 }; 222 223 #ifdef CONFIG_ARM64_SVE 224 225 static int preserve_sve_context(struct sve_context __user *ctx) 226 { 227 int err = 0; 228 u16 reserved[ARRAY_SIZE(ctx->__reserved)]; 229 unsigned int vl = current->thread.sve_vl; 230 unsigned int vq = 0; 231 232 if (test_thread_flag(TIF_SVE)) 233 vq = sve_vq_from_vl(vl); 234 235 memset(reserved, 0, sizeof(reserved)); 236 237 __put_user_error(SVE_MAGIC, &ctx->head.magic, err); 238 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16), 239 &ctx->head.size, err); 240 __put_user_error(vl, &ctx->vl, err); 241 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); 242 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); 243 244 if (vq) { 245 /* 246 * This assumes that the SVE state has already been saved to 247 * the task struct by calling preserve_fpsimd_context(). 248 */ 249 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET, 250 current->thread.sve_state, 251 SVE_SIG_REGS_SIZE(vq)); 252 } 253 254 return err ? -EFAULT : 0; 255 } 256 257 static int restore_sve_fpsimd_context(struct user_ctxs *user) 258 { 259 int err; 260 unsigned int vq; 261 struct user_fpsimd_state fpsimd; 262 struct sve_context sve; 263 264 if (__copy_from_user(&sve, user->sve, sizeof(sve))) 265 return -EFAULT; 266 267 if (sve.vl != current->thread.sve_vl) 268 return -EINVAL; 269 270 if (sve.head.size <= sizeof(*user->sve)) { 271 clear_thread_flag(TIF_SVE); 272 goto fpsimd_only; 273 } 274 275 vq = sve_vq_from_vl(sve.vl); 276 277 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq)) 278 return -EINVAL; 279 280 /* 281 * Careful: we are about __copy_from_user() directly into 282 * thread.sve_state with preemption enabled, so protection is 283 * needed to prevent a racing context switch from writing stale 284 * registers back over the new data. 285 */ 286 287 fpsimd_flush_task_state(current); 288 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ 289 290 sve_alloc(current); 291 err = __copy_from_user(current->thread.sve_state, 292 (char __user const *)user->sve + 293 SVE_SIG_REGS_OFFSET, 294 SVE_SIG_REGS_SIZE(vq)); 295 if (err) 296 return -EFAULT; 297 298 set_thread_flag(TIF_SVE); 299 300 fpsimd_only: 301 /* copy the FP and status/control registers */ 302 /* restore_sigframe() already checked that user->fpsimd != NULL. */ 303 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs, 304 sizeof(fpsimd.vregs)); 305 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err); 306 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err); 307 308 /* load the hardware registers from the fpsimd_state structure */ 309 if (!err) 310 fpsimd_update_current_state(&fpsimd); 311 312 return err ? -EFAULT : 0; 313 } 314 315 #else /* ! CONFIG_ARM64_SVE */ 316 317 /* Turn any non-optimised out attempts to use these into a link error: */ 318 extern int preserve_sve_context(void __user *ctx); 319 extern int restore_sve_fpsimd_context(struct user_ctxs *user); 320 321 #endif /* ! CONFIG_ARM64_SVE */ 322 323 324 static int parse_user_sigframe(struct user_ctxs *user, 325 struct rt_sigframe __user *sf) 326 { 327 struct sigcontext __user *const sc = &sf->uc.uc_mcontext; 328 struct _aarch64_ctx __user *head; 329 char __user *base = (char __user *)&sc->__reserved; 330 size_t offset = 0; 331 size_t limit = sizeof(sc->__reserved); 332 bool have_extra_context = false; 333 char const __user *const sfp = (char const __user *)sf; 334 335 user->fpsimd = NULL; 336 user->sve = NULL; 337 338 if (!IS_ALIGNED((unsigned long)base, 16)) 339 goto invalid; 340 341 while (1) { 342 int err = 0; 343 u32 magic, size; 344 char const __user *userp; 345 struct extra_context const __user *extra; 346 u64 extra_datap; 347 u32 extra_size; 348 struct _aarch64_ctx const __user *end; 349 u32 end_magic, end_size; 350 351 if (limit - offset < sizeof(*head)) 352 goto invalid; 353 354 if (!IS_ALIGNED(offset, 16)) 355 goto invalid; 356 357 head = (struct _aarch64_ctx __user *)(base + offset); 358 __get_user_error(magic, &head->magic, err); 359 __get_user_error(size, &head->size, err); 360 if (err) 361 return err; 362 363 if (limit - offset < size) 364 goto invalid; 365 366 switch (magic) { 367 case 0: 368 if (size) 369 goto invalid; 370 371 goto done; 372 373 case FPSIMD_MAGIC: 374 if (user->fpsimd) 375 goto invalid; 376 377 if (size < sizeof(*user->fpsimd)) 378 goto invalid; 379 380 user->fpsimd = (struct fpsimd_context __user *)head; 381 break; 382 383 case ESR_MAGIC: 384 /* ignore */ 385 break; 386 387 case SVE_MAGIC: 388 if (!system_supports_sve()) 389 goto invalid; 390 391 if (user->sve) 392 goto invalid; 393 394 if (size < sizeof(*user->sve)) 395 goto invalid; 396 397 user->sve = (struct sve_context __user *)head; 398 break; 399 400 case EXTRA_MAGIC: 401 if (have_extra_context) 402 goto invalid; 403 404 if (size < sizeof(*extra)) 405 goto invalid; 406 407 userp = (char const __user *)head; 408 409 extra = (struct extra_context const __user *)userp; 410 userp += size; 411 412 __get_user_error(extra_datap, &extra->datap, err); 413 __get_user_error(extra_size, &extra->size, err); 414 if (err) 415 return err; 416 417 /* Check for the dummy terminator in __reserved[]: */ 418 419 if (limit - offset - size < TERMINATOR_SIZE) 420 goto invalid; 421 422 end = (struct _aarch64_ctx const __user *)userp; 423 userp += TERMINATOR_SIZE; 424 425 __get_user_error(end_magic, &end->magic, err); 426 __get_user_error(end_size, &end->size, err); 427 if (err) 428 return err; 429 430 if (end_magic || end_size) 431 goto invalid; 432 433 /* Prevent looping/repeated parsing of extra_context */ 434 have_extra_context = true; 435 436 base = (__force void __user *)extra_datap; 437 if (!IS_ALIGNED((unsigned long)base, 16)) 438 goto invalid; 439 440 if (!IS_ALIGNED(extra_size, 16)) 441 goto invalid; 442 443 if (base != userp) 444 goto invalid; 445 446 /* Reject "unreasonably large" frames: */ 447 if (extra_size > sfp + SIGFRAME_MAXSZ - userp) 448 goto invalid; 449 450 /* 451 * Ignore trailing terminator in __reserved[] 452 * and start parsing extra data: 453 */ 454 offset = 0; 455 limit = extra_size; 456 457 if (!access_ok(base, limit)) 458 goto invalid; 459 460 continue; 461 462 default: 463 goto invalid; 464 } 465 466 if (size < sizeof(*head)) 467 goto invalid; 468 469 if (limit - offset < size) 470 goto invalid; 471 472 offset += size; 473 } 474 475 done: 476 return 0; 477 478 invalid: 479 return -EINVAL; 480 } 481 482 static int restore_sigframe(struct pt_regs *regs, 483 struct rt_sigframe __user *sf) 484 { 485 sigset_t set; 486 int i, err; 487 struct user_ctxs user; 488 489 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); 490 if (err == 0) 491 set_current_blocked(&set); 492 493 for (i = 0; i < 31; i++) 494 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], 495 err); 496 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); 497 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); 498 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); 499 500 /* 501 * Avoid sys_rt_sigreturn() restarting. 502 */ 503 forget_syscall(regs); 504 505 err |= !valid_user_regs(®s->user_regs, current); 506 if (err == 0) 507 err = parse_user_sigframe(&user, sf); 508 509 if (err == 0) { 510 if (!user.fpsimd) 511 return -EINVAL; 512 513 if (user.sve) { 514 if (!system_supports_sve()) 515 return -EINVAL; 516 517 err = restore_sve_fpsimd_context(&user); 518 } else { 519 err = restore_fpsimd_context(user.fpsimd); 520 } 521 } 522 523 return err; 524 } 525 526 SYSCALL_DEFINE0(rt_sigreturn) 527 { 528 struct pt_regs *regs = current_pt_regs(); 529 struct rt_sigframe __user *frame; 530 531 /* Always make any pending restarted system calls return -EINTR */ 532 current->restart_block.fn = do_no_restart_syscall; 533 534 /* 535 * Since we stacked the signal on a 128-bit boundary, then 'sp' should 536 * be word aligned here. 537 */ 538 if (regs->sp & 15) 539 goto badframe; 540 541 frame = (struct rt_sigframe __user *)regs->sp; 542 543 if (!access_ok(frame, sizeof (*frame))) 544 goto badframe; 545 546 if (restore_sigframe(regs, frame)) 547 goto badframe; 548 549 if (restore_altstack(&frame->uc.uc_stack)) 550 goto badframe; 551 552 return regs->regs[0]; 553 554 badframe: 555 arm64_notify_segfault(regs->sp); 556 return 0; 557 } 558 559 /* 560 * Determine the layout of optional records in the signal frame 561 * 562 * add_all: if true, lays out the biggest possible signal frame for 563 * this task; otherwise, generates a layout for the current state 564 * of the task. 565 */ 566 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, 567 bool add_all) 568 { 569 int err; 570 571 err = sigframe_alloc(user, &user->fpsimd_offset, 572 sizeof(struct fpsimd_context)); 573 if (err) 574 return err; 575 576 /* fault information, if valid */ 577 if (add_all || current->thread.fault_code) { 578 err = sigframe_alloc(user, &user->esr_offset, 579 sizeof(struct esr_context)); 580 if (err) 581 return err; 582 } 583 584 if (system_supports_sve()) { 585 unsigned int vq = 0; 586 587 if (add_all || test_thread_flag(TIF_SVE)) { 588 int vl = sve_max_vl; 589 590 if (!add_all) 591 vl = current->thread.sve_vl; 592 593 vq = sve_vq_from_vl(vl); 594 } 595 596 err = sigframe_alloc(user, &user->sve_offset, 597 SVE_SIG_CONTEXT_SIZE(vq)); 598 if (err) 599 return err; 600 } 601 602 return sigframe_alloc_end(user); 603 } 604 605 static int setup_sigframe(struct rt_sigframe_user_layout *user, 606 struct pt_regs *regs, sigset_t *set) 607 { 608 int i, err = 0; 609 struct rt_sigframe __user *sf = user->sigframe; 610 611 /* set up the stack frame for unwinding */ 612 __put_user_error(regs->regs[29], &user->next_frame->fp, err); 613 __put_user_error(regs->regs[30], &user->next_frame->lr, err); 614 615 for (i = 0; i < 31; i++) 616 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], 617 err); 618 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); 619 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); 620 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); 621 622 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); 623 624 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); 625 626 if (err == 0) { 627 struct fpsimd_context __user *fpsimd_ctx = 628 apply_user_offset(user, user->fpsimd_offset); 629 err |= preserve_fpsimd_context(fpsimd_ctx); 630 } 631 632 /* fault information, if valid */ 633 if (err == 0 && user->esr_offset) { 634 struct esr_context __user *esr_ctx = 635 apply_user_offset(user, user->esr_offset); 636 637 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err); 638 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err); 639 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err); 640 } 641 642 /* Scalable Vector Extension state, if present */ 643 if (system_supports_sve() && err == 0 && user->sve_offset) { 644 struct sve_context __user *sve_ctx = 645 apply_user_offset(user, user->sve_offset); 646 err |= preserve_sve_context(sve_ctx); 647 } 648 649 if (err == 0 && user->extra_offset) { 650 char __user *sfp = (char __user *)user->sigframe; 651 char __user *userp = 652 apply_user_offset(user, user->extra_offset); 653 654 struct extra_context __user *extra; 655 struct _aarch64_ctx __user *end; 656 u64 extra_datap; 657 u32 extra_size; 658 659 extra = (struct extra_context __user *)userp; 660 userp += EXTRA_CONTEXT_SIZE; 661 662 end = (struct _aarch64_ctx __user *)userp; 663 userp += TERMINATOR_SIZE; 664 665 /* 666 * extra_datap is just written to the signal frame. 667 * The value gets cast back to a void __user * 668 * during sigreturn. 669 */ 670 extra_datap = (__force u64)userp; 671 extra_size = sfp + round_up(user->size, 16) - userp; 672 673 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err); 674 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err); 675 __put_user_error(extra_datap, &extra->datap, err); 676 __put_user_error(extra_size, &extra->size, err); 677 678 /* Add the terminator */ 679 __put_user_error(0, &end->magic, err); 680 __put_user_error(0, &end->size, err); 681 } 682 683 /* set the "end" magic */ 684 if (err == 0) { 685 struct _aarch64_ctx __user *end = 686 apply_user_offset(user, user->end_offset); 687 688 __put_user_error(0, &end->magic, err); 689 __put_user_error(0, &end->size, err); 690 } 691 692 return err; 693 } 694 695 static int get_sigframe(struct rt_sigframe_user_layout *user, 696 struct ksignal *ksig, struct pt_regs *regs) 697 { 698 unsigned long sp, sp_top; 699 int err; 700 701 init_user_layout(user); 702 err = setup_sigframe_layout(user, false); 703 if (err) 704 return err; 705 706 sp = sp_top = sigsp(regs->sp, ksig); 707 708 sp = round_down(sp - sizeof(struct frame_record), 16); 709 user->next_frame = (struct frame_record __user *)sp; 710 711 sp = round_down(sp, 16) - sigframe_size(user); 712 user->sigframe = (struct rt_sigframe __user *)sp; 713 714 /* 715 * Check that we can actually write to the signal frame. 716 */ 717 if (!access_ok(user->sigframe, sp_top - sp)) 718 return -EFAULT; 719 720 return 0; 721 } 722 723 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka, 724 struct rt_sigframe_user_layout *user, int usig) 725 { 726 __sigrestore_t sigtramp; 727 728 regs->regs[0] = usig; 729 regs->sp = (unsigned long)user->sigframe; 730 regs->regs[29] = (unsigned long)&user->next_frame->fp; 731 regs->pc = (unsigned long)ka->sa.sa_handler; 732 733 if (ka->sa.sa_flags & SA_RESTORER) 734 sigtramp = ka->sa.sa_restorer; 735 else 736 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp); 737 738 regs->regs[30] = (unsigned long)sigtramp; 739 } 740 741 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set, 742 struct pt_regs *regs) 743 { 744 struct rt_sigframe_user_layout user; 745 struct rt_sigframe __user *frame; 746 int err = 0; 747 748 fpsimd_signal_preserve_current_state(); 749 750 if (get_sigframe(&user, ksig, regs)) 751 return 1; 752 753 frame = user.sigframe; 754 755 __put_user_error(0, &frame->uc.uc_flags, err); 756 __put_user_error(NULL, &frame->uc.uc_link, err); 757 758 err |= __save_altstack(&frame->uc.uc_stack, regs->sp); 759 err |= setup_sigframe(&user, regs, set); 760 if (err == 0) { 761 setup_return(regs, &ksig->ka, &user, usig); 762 if (ksig->ka.sa.sa_flags & SA_SIGINFO) { 763 err |= copy_siginfo_to_user(&frame->info, &ksig->info); 764 regs->regs[1] = (unsigned long)&frame->info; 765 regs->regs[2] = (unsigned long)&frame->uc; 766 } 767 } 768 769 return err; 770 } 771 772 static void setup_restart_syscall(struct pt_regs *regs) 773 { 774 if (is_compat_task()) 775 compat_setup_restart_syscall(regs); 776 else 777 regs->regs[8] = __NR_restart_syscall; 778 } 779 780 /* 781 * OK, we're invoking a handler 782 */ 783 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) 784 { 785 struct task_struct *tsk = current; 786 sigset_t *oldset = sigmask_to_save(); 787 int usig = ksig->sig; 788 int ret; 789 790 rseq_signal_deliver(ksig, regs); 791 792 /* 793 * Set up the stack frame 794 */ 795 if (is_compat_task()) { 796 if (ksig->ka.sa.sa_flags & SA_SIGINFO) 797 ret = compat_setup_rt_frame(usig, ksig, oldset, regs); 798 else 799 ret = compat_setup_frame(usig, ksig, oldset, regs); 800 } else { 801 ret = setup_rt_frame(usig, ksig, oldset, regs); 802 } 803 804 /* 805 * Check that the resulting registers are actually sane. 806 */ 807 ret |= !valid_user_regs(®s->user_regs, current); 808 809 /* 810 * Fast forward the stepping logic so we step into the signal 811 * handler. 812 */ 813 if (!ret) 814 user_fastforward_single_step(tsk); 815 816 signal_setup_done(ret, ksig, 0); 817 } 818 819 /* 820 * Note that 'init' is a special process: it doesn't get signals it doesn't 821 * want to handle. Thus you cannot kill init even with a SIGKILL even by 822 * mistake. 823 * 824 * Note that we go through the signals twice: once to check the signals that 825 * the kernel can handle, and then we build all the user-level signal handling 826 * stack-frames in one go after that. 827 */ 828 static void do_signal(struct pt_regs *regs) 829 { 830 unsigned long continue_addr = 0, restart_addr = 0; 831 int retval = 0; 832 struct ksignal ksig; 833 bool syscall = in_syscall(regs); 834 835 /* 836 * If we were from a system call, check for system call restarting... 837 */ 838 if (syscall) { 839 continue_addr = regs->pc; 840 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4); 841 retval = regs->regs[0]; 842 843 /* 844 * Avoid additional syscall restarting via ret_to_user. 845 */ 846 forget_syscall(regs); 847 848 /* 849 * Prepare for system call restart. We do this here so that a 850 * debugger will see the already changed PC. 851 */ 852 switch (retval) { 853 case -ERESTARTNOHAND: 854 case -ERESTARTSYS: 855 case -ERESTARTNOINTR: 856 case -ERESTART_RESTARTBLOCK: 857 regs->regs[0] = regs->orig_x0; 858 regs->pc = restart_addr; 859 break; 860 } 861 } 862 863 /* 864 * Get the signal to deliver. When running under ptrace, at this point 865 * the debugger may change all of our registers. 866 */ 867 if (get_signal(&ksig)) { 868 /* 869 * Depending on the signal settings, we may need to revert the 870 * decision to restart the system call, but skip this if a 871 * debugger has chosen to restart at a different PC. 872 */ 873 if (regs->pc == restart_addr && 874 (retval == -ERESTARTNOHAND || 875 retval == -ERESTART_RESTARTBLOCK || 876 (retval == -ERESTARTSYS && 877 !(ksig.ka.sa.sa_flags & SA_RESTART)))) { 878 regs->regs[0] = -EINTR; 879 regs->pc = continue_addr; 880 } 881 882 handle_signal(&ksig, regs); 883 return; 884 } 885 886 /* 887 * Handle restarting a different system call. As above, if a debugger 888 * has chosen to restart at a different PC, ignore the restart. 889 */ 890 if (syscall && regs->pc == restart_addr) { 891 if (retval == -ERESTART_RESTARTBLOCK) 892 setup_restart_syscall(regs); 893 user_rewind_single_step(current); 894 } 895 896 restore_saved_sigmask(); 897 } 898 899 asmlinkage void do_notify_resume(struct pt_regs *regs, 900 unsigned long thread_flags) 901 { 902 /* 903 * The assembly code enters us with IRQs off, but it hasn't 904 * informed the tracing code of that for efficiency reasons. 905 * Update the trace code with the current status. 906 */ 907 trace_hardirqs_off(); 908 909 do { 910 /* Check valid user FS if needed */ 911 addr_limit_user_check(); 912 913 if (thread_flags & _TIF_NEED_RESCHED) { 914 /* Unmask Debug and SError for the next task */ 915 local_daif_restore(DAIF_PROCCTX_NOIRQ); 916 917 schedule(); 918 } else { 919 local_daif_restore(DAIF_PROCCTX); 920 921 if (thread_flags & _TIF_UPROBE) 922 uprobe_notify_resume(regs); 923 924 if (thread_flags & _TIF_SIGPENDING) 925 do_signal(regs); 926 927 if (thread_flags & _TIF_NOTIFY_RESUME) { 928 clear_thread_flag(TIF_NOTIFY_RESUME); 929 tracehook_notify_resume(regs); 930 rseq_handle_notify_resume(NULL, regs); 931 } 932 933 if (thread_flags & _TIF_FOREIGN_FPSTATE) 934 fpsimd_restore_current_state(); 935 } 936 937 local_daif_mask(); 938 thread_flags = READ_ONCE(current_thread_info()->flags); 939 } while (thread_flags & _TIF_WORK_MASK); 940 } 941 942 unsigned long __ro_after_init signal_minsigstksz; 943 944 /* 945 * Determine the stack space required for guaranteed signal devliery. 946 * This function is used to populate AT_MINSIGSTKSZ at process startup. 947 * cpufeatures setup is assumed to be complete. 948 */ 949 void __init minsigstksz_setup(void) 950 { 951 struct rt_sigframe_user_layout user; 952 953 init_user_layout(&user); 954 955 /* 956 * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't 957 * be big enough, but it's our best guess: 958 */ 959 if (WARN_ON(setup_sigframe_layout(&user, true))) 960 return; 961 962 signal_minsigstksz = sigframe_size(&user) + 963 round_up(sizeof(struct frame_record), 16) + 964 16; /* max alignment padding */ 965 } 966