arch/arm64/kernel/signal.c

   1 /*
   2  * Based on arch/arm/kernel/signal.c
   3  *
   4  * Copyright (C) 1995-2009 Russell King
   5  * Copyright (C) 2012 ARM Ltd.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/cache.h>
  21 #include <linux/compat.h>
  22 #include <linux/errno.h>
  23 #include <linux/kernel.h>
  24 #include <linux/signal.h>
  25 #include <linux/personality.h>
  26 #include <linux/freezer.h>
  27 #include <linux/stddef.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/sizes.h>
  30 #include <linux/string.h>
  31 #include <linux/tracehook.h>
  32 #include <linux/ratelimit.h>
  33 #include <linux/syscalls.h>
  34
  35 #include <asm/daifflags.h>
  36 #include <asm/debug-monitors.h>
  37 #include <asm/elf.h>
  38 #include <asm/cacheflush.h>
  39 #include <asm/ucontext.h>
  40 #include <asm/unistd.h>
  41 #include <asm/fpsimd.h>
  42 #include <asm/ptrace.h>
  43 #include <asm/signal32.h>
  44 #include <asm/traps.h>
  45 #include <asm/vdso.h>
  46
  47 /*
  48  * Do a signal return; undo the signal stack. These are aligned to 128-bit.
  49  */
  50 struct rt_sigframe {
  51         struct siginfo info;
  52         struct ucontext uc;
  53 };
  54
  55 struct frame_record {
  56         u64 fp;
  57         u64 lr;
  58 };
  59
  60 struct rt_sigframe_user_layout {
  61         struct rt_sigframe __user *sigframe;
  62         struct frame_record __user *next_frame;
  63
  64         unsigned long size;     /* size of allocated sigframe data */
  65         unsigned long limit;    /* largest allowed size */
  66
  67         unsigned long fpsimd_offset;
  68         unsigned long esr_offset;
  69         unsigned long sve_offset;
  70         unsigned long extra_offset;
  71         unsigned long end_offset;
  72 };
  73
  74 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
  75 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
  76 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
  77
  78 static void init_user_layout(struct rt_sigframe_user_layout *user)
  79 {
  80         const size_t reserved_size =
  81                 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
  82
  83         memset(user, 0, sizeof(*user));
  84         user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
  85
  86         user->limit = user->size + reserved_size;
  87
  88         user->limit -= TERMINATOR_SIZE;
  89         user->limit -= EXTRA_CONTEXT_SIZE;
  90         /* Reserve space for extension and terminator ^ */
  91 }
  92
  93 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
  94 {
  95         return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
  96 }
  97
  98 /*
  99  * Sanity limit on the approximate maximum size of signal frame we'll
 100  * try to generate.  Stack alignment padding and the frame record are
 101  * not taken into account.  This limit is not a guarantee and is
 102  * NOT ABI.
 103  */
 104 #define SIGFRAME_MAXSZ SZ_64K
 105
 106 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
 107                             unsigned long *offset, size_t size, bool extend)
 108 {
 109         size_t padded_size = round_up(size, 16);
 110
 111         if (padded_size > user->limit - user->size &&
 112             !user->extra_offset &&
 113             extend) {
 114                 int ret;
 115
 116                 user->limit += EXTRA_CONTEXT_SIZE;
 117                 ret = __sigframe_alloc(user, &user->extra_offset,
 118                                        sizeof(struct extra_context), false);
 119                 if (ret) {
 120                         user->limit -= EXTRA_CONTEXT_SIZE;
 121                         return ret;
 122                 }
 123
 124                 /* Reserve space for the __reserved[] terminator */
 125                 user->size += TERMINATOR_SIZE;
 126
 127                 /*
 128                  * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
 129                  * the terminator:
 130                  */
 131                 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
 132         }
 133
 134         /* Still not enough space?  Bad luck! */
 135         if (padded_size > user->limit - user->size)
 136                 return -ENOMEM;
 137
 138         *offset = user->size;
 139         user->size += padded_size;
 140
 141         return 0;
 142 }
 143
 144 /*
 145  * Allocate space for an optional record of <size> bytes in the user
 146  * signal frame.  The offset from the signal frame base address to the
 147  * allocated block is assigned to *offset.
 148  */
 149 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
 150                           unsigned long *offset, size_t size)
 151 {
 152         return __sigframe_alloc(user, offset, size, true);
 153 }
 154
 155 /* Allocate the null terminator record and prevent further allocations */
 156 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
 157 {
 158         int ret;
 159
 160         /* Un-reserve the space reserved for the terminator: */
 161         user->limit += TERMINATOR_SIZE;
 162
 163         ret = sigframe_alloc(user, &user->end_offset,
 164                              sizeof(struct _aarch64_ctx));
 165         if (ret)
 166                 return ret;
 167
 168         /* Prevent further allocation: */
 169         user->limit = user->size;
 170         return 0;
 171 }
 172
 173 static void __user *apply_user_offset(
 174         struct rt_sigframe_user_layout const *user, unsigned long offset)
 175 {
 176         char __user *base = (char __user *)user->sigframe;
 177
 178         return base + offset;
 179 }
 180
 181 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
 182 {
 183         struct user_fpsimd_state const *fpsimd =
 184                 &current->thread.uw.fpsimd_state;
 185         int err;
 186
 187         /* copy the FP and status/control registers */
 188         err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
 189         __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
 190         __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
 191
 192         /* copy the magic/size information */
 193         __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
 194         __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
 195
 196         return err ? -EFAULT : 0;
 197 }
 198
 199 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
 200 {
 201         struct user_fpsimd_state fpsimd;
 202         __u32 magic, size;
 203         int err = 0;
 204
 205         /* check the magic/size information */
 206         __get_user_error(magic, &ctx->head.magic, err);
 207         __get_user_error(size, &ctx->head.size, err);
 208         if (err)
 209                 return -EFAULT;
 210         if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
 211                 return -EINVAL;
 212
 213         /* copy the FP and status/control registers */
 214         err = __copy_from_user(fpsimd.vregs, ctx->vregs,
 215                                sizeof(fpsimd.vregs));
 216         __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
 217         __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
 218
 219         clear_thread_flag(TIF_SVE);
 220
 221         /* load the hardware registers from the fpsimd_state structure */
 222         if (!err)
 223                 fpsimd_update_current_state(&fpsimd);
 224
 225         return err ? -EFAULT : 0;
 226 }
 227
 228
 229 struct user_ctxs {
 230         struct fpsimd_context __user *fpsimd;
 231         struct sve_context __user *sve;
 232 };
 233
 234 #ifdef CONFIG_ARM64_SVE
 235
 236 static int preserve_sve_context(struct sve_context __user *ctx)
 237 {
 238         int err = 0;
 239         u16 reserved[ARRAY_SIZE(ctx->__reserved)];
 240         unsigned int vl = current->thread.sve_vl;
 241         unsigned int vq = 0;
 242
 243         if (test_thread_flag(TIF_SVE))
 244                 vq = sve_vq_from_vl(vl);
 245
 246         memset(reserved, 0, sizeof(reserved));
 247
 248         __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
 249         __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
 250                          &ctx->head.size, err);
 251         __put_user_error(vl, &ctx->vl, err);
 252         BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
 253         err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
 254
 255         if (vq) {
 256                 /*
 257                  * This assumes that the SVE state has already been saved to
 258                  * the task struct by calling preserve_fpsimd_context().
 259                  */
 260                 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
 261                                       current->thread.sve_state,
 262                                       SVE_SIG_REGS_SIZE(vq));
 263         }
 264
 265         return err ? -EFAULT : 0;
 266 }
 267
 268 static int restore_sve_fpsimd_context(struct user_ctxs *user)
 269 {
 270         int err;
 271         unsigned int vq;
 272         struct user_fpsimd_state fpsimd;
 273         struct sve_context sve;
 274
 275         if (__copy_from_user(&sve, user->sve, sizeof(sve)))
 276                 return -EFAULT;
 277
 278         if (sve.vl != current->thread.sve_vl)
 279                 return -EINVAL;
 280
 281         if (sve.head.size <= sizeof(*user->sve)) {
 282                 clear_thread_flag(TIF_SVE);
 283                 goto fpsimd_only;
 284         }
 285
 286         vq = sve_vq_from_vl(sve.vl);
 287
 288         if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
 289                 return -EINVAL;
 290
 291         /*
 292          * Careful: we are about __copy_from_user() directly into
 293          * thread.sve_state with preemption enabled, so protection is
 294          * needed to prevent a racing context switch from writing stale
 295          * registers back over the new data.
 296          */
 297
 298         fpsimd_flush_task_state(current);
 299         barrier();
 300         /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
 301
 302         set_thread_flag(TIF_FOREIGN_FPSTATE);
 303         barrier();
 304         /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
 305
 306         sve_alloc(current);
 307         err = __copy_from_user(current->thread.sve_state,
 308                                (char __user const *)user->sve +
 309                                         SVE_SIG_REGS_OFFSET,
 310                                SVE_SIG_REGS_SIZE(vq));
 311         if (err)
 312                 return -EFAULT;
 313
 314         set_thread_flag(TIF_SVE);
 315
 316 fpsimd_only:
 317         /* copy the FP and status/control registers */
 318         /* restore_sigframe() already checked that user->fpsimd != NULL. */
 319         err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
 320                                sizeof(fpsimd.vregs));
 321         __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
 322         __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
 323
 324         /* load the hardware registers from the fpsimd_state structure */
 325         if (!err)
 326                 fpsimd_update_current_state(&fpsimd);
 327
 328         return err ? -EFAULT : 0;
 329 }
 330
 331 #else /* ! CONFIG_ARM64_SVE */
 332
 333 /* Turn any non-optimised out attempts to use these into a link error: */
 334 extern int preserve_sve_context(void __user *ctx);
 335 extern int restore_sve_fpsimd_context(struct user_ctxs *user);
 336
 337 #endif /* ! CONFIG_ARM64_SVE */
 338
 339
 340 static int parse_user_sigframe(struct user_ctxs *user,
 341                                struct rt_sigframe __user *sf)
 342 {
 343         struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
 344         struct _aarch64_ctx __user *head;
 345         char __user *base = (char __user *)&sc->__reserved;
 346         size_t offset = 0;
 347         size_t limit = sizeof(sc->__reserved);
 348         bool have_extra_context = false;
 349         char const __user *const sfp = (char const __user *)sf;
 350
 351         user->fpsimd = NULL;
 352         user->sve = NULL;
 353
 354         if (!IS_ALIGNED((unsigned long)base, 16))
 355                 goto invalid;
 356
 357         while (1) {
 358                 int err = 0;
 359                 u32 magic, size;
 360                 char const __user *userp;
 361                 struct extra_context const __user *extra;
 362                 u64 extra_datap;
 363                 u32 extra_size;
 364                 struct _aarch64_ctx const __user *end;
 365                 u32 end_magic, end_size;
 366
 367                 if (limit - offset < sizeof(*head))
 368                         goto invalid;
 369
 370                 if (!IS_ALIGNED(offset, 16))
 371                         goto invalid;
 372
 373                 head = (struct _aarch64_ctx __user *)(base + offset);
 374                 __get_user_error(magic, &head->magic, err);
 375                 __get_user_error(size, &head->size, err);
 376                 if (err)
 377                         return err;
 378
 379                 if (limit - offset < size)
 380                         goto invalid;
 381
 382                 switch (magic) {
 383                 case 0:
 384                         if (size)
 385                                 goto invalid;
 386
 387                         goto done;
 388
 389                 case FPSIMD_MAGIC:
 390                         if (user->fpsimd)
 391                                 goto invalid;
 392
 393                         if (size < sizeof(*user->fpsimd))
 394                                 goto invalid;
 395
 396                         user->fpsimd = (struct fpsimd_context __user *)head;
 397                         break;
 398
 399                 case ESR_MAGIC:
 400                         /* ignore */
 401                         break;
 402
 403                 case SVE_MAGIC:
 404                         if (!system_supports_sve())
 405                                 goto invalid;
 406
 407                         if (user->sve)
 408                                 goto invalid;
 409
 410                         if (size < sizeof(*user->sve))
 411                                 goto invalid;
 412
 413                         user->sve = (struct sve_context __user *)head;
 414                         break;
 415
 416                 case EXTRA_MAGIC:
 417                         if (have_extra_context)
 418                                 goto invalid;
 419
 420                         if (size < sizeof(*extra))
 421                                 goto invalid;
 422
 423                         userp = (char const __user *)head;
 424
 425                         extra = (struct extra_context const __user *)userp;
 426                         userp += size;
 427
 428                         __get_user_error(extra_datap, &extra->datap, err);
 429                         __get_user_error(extra_size, &extra->size, err);
 430                         if (err)
 431                                 return err;
 432
 433                         /* Check for the dummy terminator in __reserved[]: */
 434
 435                         if (limit - offset - size < TERMINATOR_SIZE)
 436                                 goto invalid;
 437
 438                         end = (struct _aarch64_ctx const __user *)userp;
 439                         userp += TERMINATOR_SIZE;
 440
 441                         __get_user_error(end_magic, &end->magic, err);
 442                         __get_user_error(end_size, &end->size, err);
 443                         if (err)
 444                                 return err;
 445
 446                         if (end_magic || end_size)
 447                                 goto invalid;
 448
 449                         /* Prevent looping/repeated parsing of extra_context */
 450                         have_extra_context = true;
 451
 452                         base = (__force void __user *)extra_datap;
 453                         if (!IS_ALIGNED((unsigned long)base, 16))
 454                                 goto invalid;
 455
 456                         if (!IS_ALIGNED(extra_size, 16))
 457                                 goto invalid;
 458
 459                         if (base != userp)
 460                                 goto invalid;
 461
 462                         /* Reject "unreasonably large" frames: */
 463                         if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
 464                                 goto invalid;
 465
 466                         /*
 467                          * Ignore trailing terminator in __reserved[]
 468                          * and start parsing extra data:
 469                          */
 470                         offset = 0;
 471                         limit = extra_size;
 472
 473                         if (!access_ok(base, limit))
 474                                 goto invalid;
 475
 476                         continue;
 477
 478                 default:
 479                         goto invalid;
 480                 }
 481
 482                 if (size < sizeof(*head))
 483                         goto invalid;
 484
 485                 if (limit - offset < size)
 486                         goto invalid;
 487
 488                 offset += size;
 489         }
 490
 491 done:
 492         return 0;
 493
 494 invalid:
 495         return -EINVAL;
 496 }
 497
 498 static int restore_sigframe(struct pt_regs *regs,
 499                             struct rt_sigframe __user *sf)
 500 {
 501         sigset_t set;
 502         int i, err;
 503         struct user_ctxs user;
 504
 505         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 506         if (err == 0)
 507                 set_current_blocked(&set);
 508
 509         for (i = 0; i < 31; i++)
 510                 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 511                                  err);
 512         __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 513         __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 514         __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 515
 516         /*
 517          * Avoid sys_rt_sigreturn() restarting.
 518          */
 519         forget_syscall(regs);
 520
 521         err |= !valid_user_regs(&regs->user_regs, current);
 522         if (err == 0)
 523                 err = parse_user_sigframe(&user, sf);
 524
 525         if (err == 0) {
 526                 if (!user.fpsimd)
 527                         return -EINVAL;
 528
 529                 if (user.sve) {
 530                         if (!system_supports_sve())
 531                                 return -EINVAL;
 532
 533                         err = restore_sve_fpsimd_context(&user);
 534                 } else {
 535                         err = restore_fpsimd_context(user.fpsimd);
 536                 }
 537         }
 538
 539         return err;
 540 }
 541
 542 SYSCALL_DEFINE0(rt_sigreturn)
 543 {
 544         struct pt_regs *regs = current_pt_regs();
 545         struct rt_sigframe __user *frame;
 546
 547         /* Always make any pending restarted system calls return -EINTR */
 548         current->restart_block.fn = do_no_restart_syscall;
 549
 550         /*
 551          * Since we stacked the signal on a 128-bit boundary, then 'sp' should
 552          * be word aligned here.
 553          */
 554         if (regs->sp & 15)
 555                 goto badframe;
 556
 557         frame = (struct rt_sigframe __user *)regs->sp;
 558
 559         if (!access_ok(frame, sizeof (*frame)))
 560                 goto badframe;
 561
 562         if (restore_sigframe(regs, frame))
 563                 goto badframe;
 564
 565         if (restore_altstack(&frame->uc.uc_stack))
 566                 goto badframe;
 567
 568         return regs->regs[0];
 569
 570 badframe:
 571         arm64_notify_segfault(regs->sp);
 572         return 0;
 573 }
 574
 575 /*
 576  * Determine the layout of optional records in the signal frame
 577  *
 578  * add_all: if true, lays out the biggest possible signal frame for
 579  *      this task; otherwise, generates a layout for the current state
 580  *      of the task.
 581  */
 582 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
 583                                  bool add_all)
 584 {
 585         int err;
 586
 587         err = sigframe_alloc(user, &user->fpsimd_offset,
 588                              sizeof(struct fpsimd_context));
 589         if (err)
 590                 return err;
 591
 592         /* fault information, if valid */
 593         if (add_all || current->thread.fault_code) {
 594                 err = sigframe_alloc(user, &user->esr_offset,
 595                                      sizeof(struct esr_context));
 596                 if (err)
 597                         return err;
 598         }
 599
 600         if (system_supports_sve()) {
 601                 unsigned int vq = 0;
 602
 603                 if (add_all || test_thread_flag(TIF_SVE)) {
 604                         int vl = sve_max_vl;
 605
 606                         if (!add_all)
 607                                 vl = current->thread.sve_vl;
 608
 609                         vq = sve_vq_from_vl(vl);
 610                 }
 611
 612                 err = sigframe_alloc(user, &user->sve_offset,
 613                                      SVE_SIG_CONTEXT_SIZE(vq));
 614                 if (err)
 615                         return err;
 616         }
 617
 618         return sigframe_alloc_end(user);
 619 }
 620
 621 static int setup_sigframe(struct rt_sigframe_user_layout *user,
 622                           struct pt_regs *regs, sigset_t *set)
 623 {
 624         int i, err = 0;
 625         struct rt_sigframe __user *sf = user->sigframe;
 626
 627         /* set up the stack frame for unwinding */
 628         __put_user_error(regs->regs[29], &user->next_frame->fp, err);
 629         __put_user_error(regs->regs[30], &user->next_frame->lr, err);
 630
 631         for (i = 0; i < 31; i++)
 632                 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 633                                  err);
 634         __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 635         __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 636         __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 637
 638         __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 639
 640         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 641
 642         if (err == 0) {
 643                 struct fpsimd_context __user *fpsimd_ctx =
 644                         apply_user_offset(user, user->fpsimd_offset);
 645                 err |= preserve_fpsimd_context(fpsimd_ctx);
 646         }
 647
 648         /* fault information, if valid */
 649         if (err == 0 && user->esr_offset) {
 650                 struct esr_context __user *esr_ctx =
 651                         apply_user_offset(user, user->esr_offset);
 652
 653                 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
 654                 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
 655                 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
 656         }
 657
 658         /* Scalable Vector Extension state, if present */
 659         if (system_supports_sve() && err == 0 && user->sve_offset) {
 660                 struct sve_context __user *sve_ctx =
 661                         apply_user_offset(user, user->sve_offset);
 662                 err |= preserve_sve_context(sve_ctx);
 663         }
 664
 665         if (err == 0 && user->extra_offset) {
 666                 char __user *sfp = (char __user *)user->sigframe;
 667                 char __user *userp =
 668                         apply_user_offset(user, user->extra_offset);
 669
 670                 struct extra_context __user *extra;
 671                 struct _aarch64_ctx __user *end;
 672                 u64 extra_datap;
 673                 u32 extra_size;
 674
 675                 extra = (struct extra_context __user *)userp;
 676                 userp += EXTRA_CONTEXT_SIZE;
 677
 678                 end = (struct _aarch64_ctx __user *)userp;
 679                 userp += TERMINATOR_SIZE;
 680
 681                 /*
 682                  * extra_datap is just written to the signal frame.
 683                  * The value gets cast back to a void __user *
 684                  * during sigreturn.
 685                  */
 686                 extra_datap = (__force u64)userp;
 687                 extra_size = sfp + round_up(user->size, 16) - userp;
 688
 689                 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
 690                 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
 691                 __put_user_error(extra_datap, &extra->datap, err);
 692                 __put_user_error(extra_size, &extra->size, err);
 693
 694                 /* Add the terminator */
 695                 __put_user_error(0, &end->magic, err);
 696                 __put_user_error(0, &end->size, err);
 697         }
 698
 699         /* set the "end" magic */
 700         if (err == 0) {
 701                 struct _aarch64_ctx __user *end =
 702                         apply_user_offset(user, user->end_offset);
 703
 704                 __put_user_error(0, &end->magic, err);
 705                 __put_user_error(0, &end->size, err);
 706         }
 707
 708         return err;
 709 }
 710
 711 static int get_sigframe(struct rt_sigframe_user_layout *user,
 712                          struct ksignal *ksig, struct pt_regs *regs)
 713 {
 714         unsigned long sp, sp_top;
 715         int err;
 716
 717         init_user_layout(user);
 718         err = setup_sigframe_layout(user, false);
 719         if (err)
 720                 return err;
 721
 722         sp = sp_top = sigsp(regs->sp, ksig);
 723
 724         sp = round_down(sp - sizeof(struct frame_record), 16);
 725         user->next_frame = (struct frame_record __user *)sp;
 726
 727         sp = round_down(sp, 16) - sigframe_size(user);
 728         user->sigframe = (struct rt_sigframe __user *)sp;
 729
 730         /*
 731          * Check that we can actually write to the signal frame.
 732          */
 733         if (!access_ok(user->sigframe, sp_top - sp))
 734                 return -EFAULT;
 735
 736         return 0;
 737 }
 738
 739 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 740                          struct rt_sigframe_user_layout *user, int usig)
 741 {
 742         __sigrestore_t sigtramp;
 743
 744         regs->regs[0] = usig;
 745         regs->sp = (unsigned long)user->sigframe;
 746         regs->regs[29] = (unsigned long)&user->next_frame->fp;
 747         regs->pc = (unsigned long)ka->sa.sa_handler;
 748
 749         if (ka->sa.sa_flags & SA_RESTORER)
 750                 sigtramp = ka->sa.sa_restorer;
 751         else
 752                 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
 753
 754         regs->regs[30] = (unsigned long)sigtramp;
 755 }
 756
 757 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
 758                           struct pt_regs *regs)
 759 {
 760         struct rt_sigframe_user_layout user;
 761         struct rt_sigframe __user *frame;
 762         int err = 0;
 763
 764         fpsimd_signal_preserve_current_state();
 765
 766         if (get_sigframe(&user, ksig, regs))
 767                 return 1;
 768
 769         frame = user.sigframe;
 770
 771         __put_user_error(0, &frame->uc.uc_flags, err);
 772         __put_user_error(NULL, &frame->uc.uc_link, err);
 773
 774         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 775         err |= setup_sigframe(&user, regs, set);
 776         if (err == 0) {
 777                 setup_return(regs, &ksig->ka, &user, usig);
 778                 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 779                         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 780                         regs->regs[1] = (unsigned long)&frame->info;
 781                         regs->regs[2] = (unsigned long)&frame->uc;
 782                 }
 783         }
 784
 785         return err;
 786 }
 787
 788 static void setup_restart_syscall(struct pt_regs *regs)
 789 {
 790         if (is_compat_task())
 791                 compat_setup_restart_syscall(regs);
 792         else
 793                 regs->regs[8] = __NR_restart_syscall;
 794 }
 795
 796 /*
 797  * OK, we're invoking a handler
 798  */
 799 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 800 {
 801         struct task_struct *tsk = current;
 802         sigset_t *oldset = sigmask_to_save();
 803         int usig = ksig->sig;
 804         int ret;
 805
 806         rseq_signal_deliver(ksig, regs);
 807
 808         /*
 809          * Set up the stack frame
 810          */
 811         if (is_compat_task()) {
 812                 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 813                         ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
 814                 else
 815                         ret = compat_setup_frame(usig, ksig, oldset, regs);
 816         } else {
 817                 ret = setup_rt_frame(usig, ksig, oldset, regs);
 818         }
 819
 820         /*
 821          * Check that the resulting registers are actually sane.
 822          */
 823         ret |= !valid_user_regs(&regs->user_regs, current);
 824
 825         /*
 826          * Fast forward the stepping logic so we step into the signal
 827          * handler.
 828          */
 829         if (!ret)
 830                 user_fastforward_single_step(tsk);
 831
 832         signal_setup_done(ret, ksig, 0);
 833 }
 834
 835 /*
 836  * Note that 'init' is a special process: it doesn't get signals it doesn't
 837  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 838  * mistake.
 839  *
 840  * Note that we go through the signals twice: once to check the signals that
 841  * the kernel can handle, and then we build all the user-level signal handling
 842  * stack-frames in one go after that.
 843  */
 844 static void do_signal(struct pt_regs *regs)
 845 {
 846         unsigned long continue_addr = 0, restart_addr = 0;
 847         int retval = 0;
 848         struct ksignal ksig;
 849         bool syscall = in_syscall(regs);
 850
 851         /*
 852          * If we were from a system call, check for system call restarting...
 853          */
 854         if (syscall) {
 855                 continue_addr = regs->pc;
 856                 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
 857                 retval = regs->regs[0];
 858
 859                 /*
 860                  * Avoid additional syscall restarting via ret_to_user.
 861                  */
 862                 forget_syscall(regs);
 863
 864                 /*
 865                  * Prepare for system call restart. We do this here so that a
 866                  * debugger will see the already changed PC.
 867                  */
 868                 switch (retval) {
 869                 case -ERESTARTNOHAND:
 870                 case -ERESTARTSYS:
 871                 case -ERESTARTNOINTR:
 872                 case -ERESTART_RESTARTBLOCK:
 873                         regs->regs[0] = regs->orig_x0;
 874                         regs->pc = restart_addr;
 875                         break;
 876                 }
 877         }
 878
 879         /*
 880          * Get the signal to deliver. When running under ptrace, at this point
 881          * the debugger may change all of our registers.
 882          */
 883         if (get_signal(&ksig)) {
 884                 /*
 885                  * Depending on the signal settings, we may need to revert the
 886                  * decision to restart the system call, but skip this if a
 887                  * debugger has chosen to restart at a different PC.
 888                  */
 889                 if (regs->pc == restart_addr &&
 890                     (retval == -ERESTARTNOHAND ||
 891                      retval == -ERESTART_RESTARTBLOCK ||
 892                      (retval == -ERESTARTSYS &&
 893                       !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
 894                         regs->regs[0] = -EINTR;
 895                         regs->pc = continue_addr;
 896                 }
 897
 898                 handle_signal(&ksig, regs);
 899                 return;
 900         }
 901
 902         /*
 903          * Handle restarting a different system call. As above, if a debugger
 904          * has chosen to restart at a different PC, ignore the restart.
 905          */
 906         if (syscall && regs->pc == restart_addr) {
 907                 if (retval == -ERESTART_RESTARTBLOCK)
 908                         setup_restart_syscall(regs);
 909                 user_rewind_single_step(current);
 910         }
 911
 912         restore_saved_sigmask();
 913 }
 914
 915 asmlinkage void do_notify_resume(struct pt_regs *regs,
 916                                  unsigned long thread_flags)
 917 {
 918         /*
 919          * The assembly code enters us with IRQs off, but it hasn't
 920          * informed the tracing code of that for efficiency reasons.
 921          * Update the trace code with the current status.
 922          */
 923         trace_hardirqs_off();
 924
 925         do {
 926                 /* Check valid user FS if needed */
 927                 addr_limit_user_check();
 928
 929                 if (thread_flags & _TIF_NEED_RESCHED) {
 930                         /* Unmask Debug and SError for the next task */
 931                         local_daif_restore(DAIF_PROCCTX_NOIRQ);
 932
 933                         schedule();
 934                 } else {
 935                         local_daif_restore(DAIF_PROCCTX);
 936
 937                         if (thread_flags & _TIF_UPROBE)
 938                                 uprobe_notify_resume(regs);
 939
 940                         if (thread_flags & _TIF_SIGPENDING)
 941                                 do_signal(regs);
 942
 943                         if (thread_flags & _TIF_NOTIFY_RESUME) {
 944                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 945                                 tracehook_notify_resume(regs);
 946                                 rseq_handle_notify_resume(NULL, regs);
 947                         }
 948
 949                         if (thread_flags & _TIF_FOREIGN_FPSTATE)
 950                                 fpsimd_restore_current_state();
 951                 }
 952
 953                 local_daif_mask();
 954                 thread_flags = READ_ONCE(current_thread_info()->flags);
 955         } while (thread_flags & _TIF_WORK_MASK);
 956 }
 957
 958 unsigned long __ro_after_init signal_minsigstksz;
 959
 960 /*
 961  * Determine the stack space required for guaranteed signal devliery.
 962  * This function is used to populate AT_MINSIGSTKSZ at process startup.
 963  * cpufeatures setup is assumed to be complete.
 964  */
 965 void __init minsigstksz_setup(void)
 966 {
 967         struct rt_sigframe_user_layout user;
 968
 969         init_user_layout(&user);
 970
 971         /*
 972          * If this fails, SIGFRAME_MAXSZ needs to be enlarged.  It won't
 973          * be big enough, but it's our best guess:
 974          */
 975         if (WARN_ON(setup_sigframe_layout(&user, true)))
 976                 return;
 977
 978         signal_minsigstksz = sigframe_size(&user) +
 979                 round_up(sizeof(struct frame_record), 16) +
 980                 16; /* max alignment padding */
 981 }