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/compat.h>
  21 #include <linux/errno.h>
  22 #include <linux/kernel.h>
  23 #include <linux/signal.h>
  24 #include <linux/personality.h>
  25 #include <linux/freezer.h>
  26 #include <linux/stddef.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/sizes.h>
  29 #include <linux/string.h>
  30 #include <linux/tracehook.h>
  31 #include <linux/ratelimit.h>
  32 #include <linux/syscalls.h>
  33
  34 #include <asm/daifflags.h>
  35 #include <asm/debug-monitors.h>
  36 #include <asm/elf.h>
  37 #include <asm/cacheflush.h>
  38 #include <asm/ucontext.h>
  39 #include <asm/unistd.h>
  40 #include <asm/fpsimd.h>
  41 #include <asm/ptrace.h>
  42 #include <asm/signal32.h>
  43 #include <asm/vdso.h>
  44
  45 /*
  46  * Do a signal return; undo the signal stack. These are aligned to 128-bit.
  47  */
  48 struct rt_sigframe {
  49         struct siginfo info;
  50         struct ucontext uc;
  51 };
  52
  53 struct frame_record {
  54         u64 fp;
  55         u64 lr;
  56 };
  57
  58 struct rt_sigframe_user_layout {
  59         struct rt_sigframe __user *sigframe;
  60         struct frame_record __user *next_frame;
  61
  62         unsigned long size;     /* size of allocated sigframe data */
  63         unsigned long limit;    /* largest allowed size */
  64
  65         unsigned long fpsimd_offset;
  66         unsigned long esr_offset;
  67         unsigned long sve_offset;
  68         unsigned long extra_offset;
  69         unsigned long end_offset;
  70 };
  71
  72 #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
  73 #define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
  74 #define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
  75
  76 static void init_user_layout(struct rt_sigframe_user_layout *user)
  77 {
  78         const size_t reserved_size =
  79                 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
  80
  81         memset(user, 0, sizeof(*user));
  82         user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
  83
  84         user->limit = user->size + reserved_size;
  85
  86         user->limit -= TERMINATOR_SIZE;
  87         user->limit -= EXTRA_CONTEXT_SIZE;
  88         /* Reserve space for extension and terminator ^ */
  89 }
  90
  91 static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
  92 {
  93         return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
  94 }
  95
  96 /*
  97  * Sanity limit on the approximate maximum size of signal frame we'll
  98  * try to generate.  Stack alignment padding and the frame record are
  99  * not taken into account.  This limit is not a guarantee and is
 100  * NOT ABI.
 101  */
 102 #define SIGFRAME_MAXSZ SZ_64K
 103
 104 static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
 105                             unsigned long *offset, size_t size, bool extend)
 106 {
 107         size_t padded_size = round_up(size, 16);
 108
 109         if (padded_size > user->limit - user->size &&
 110             !user->extra_offset &&
 111             extend) {
 112                 int ret;
 113
 114                 user->limit += EXTRA_CONTEXT_SIZE;
 115                 ret = __sigframe_alloc(user, &user->extra_offset,
 116                                        sizeof(struct extra_context), false);
 117                 if (ret) {
 118                         user->limit -= EXTRA_CONTEXT_SIZE;
 119                         return ret;
 120                 }
 121
 122                 /* Reserve space for the __reserved[] terminator */
 123                 user->size += TERMINATOR_SIZE;
 124
 125                 /*
 126                  * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
 127                  * the terminator:
 128                  */
 129                 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
 130         }
 131
 132         /* Still not enough space?  Bad luck! */
 133         if (padded_size > user->limit - user->size)
 134                 return -ENOMEM;
 135
 136         *offset = user->size;
 137         user->size += padded_size;
 138
 139         return 0;
 140 }
 141
 142 /*
 143  * Allocate space for an optional record of <size> bytes in the user
 144  * signal frame.  The offset from the signal frame base address to the
 145  * allocated block is assigned to *offset.
 146  */
 147 static int sigframe_alloc(struct rt_sigframe_user_layout *user,
 148                           unsigned long *offset, size_t size)
 149 {
 150         return __sigframe_alloc(user, offset, size, true);
 151 }
 152
 153 /* Allocate the null terminator record and prevent further allocations */
 154 static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
 155 {
 156         int ret;
 157
 158         /* Un-reserve the space reserved for the terminator: */
 159         user->limit += TERMINATOR_SIZE;
 160
 161         ret = sigframe_alloc(user, &user->end_offset,
 162                              sizeof(struct _aarch64_ctx));
 163         if (ret)
 164                 return ret;
 165
 166         /* Prevent further allocation: */
 167         user->limit = user->size;
 168         return 0;
 169 }
 170
 171 static void __user *apply_user_offset(
 172         struct rt_sigframe_user_layout const *user, unsigned long offset)
 173 {
 174         char __user *base = (char __user *)user->sigframe;
 175
 176         return base + offset;
 177 }
 178
 179 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
 180 {
 181         struct user_fpsimd_state const *fpsimd =
 182                 &current->thread.fpsimd_state.user_fpsimd;
 183         int err;
 184
 185         /* copy the FP and status/control registers */
 186         err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
 187         __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
 188         __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
 189
 190         /* copy the magic/size information */
 191         __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
 192         __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
 193
 194         return err ? -EFAULT : 0;
 195 }
 196
 197 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
 198 {
 199         struct user_fpsimd_state fpsimd;
 200         __u32 magic, size;
 201         int err = 0;
 202
 203         /* check the magic/size information */
 204         __get_user_error(magic, &ctx->head.magic, err);
 205         __get_user_error(size, &ctx->head.size, err);
 206         if (err)
 207                 return -EFAULT;
 208         if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
 209                 return -EINVAL;
 210
 211         /* copy the FP and status/control registers */
 212         err = __copy_from_user(fpsimd.vregs, ctx->vregs,
 213                                sizeof(fpsimd.vregs));
 214         __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
 215         __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
 216
 217         clear_thread_flag(TIF_SVE);
 218
 219         /* load the hardware registers from the fpsimd_state structure */
 220         if (!err)
 221                 fpsimd_update_current_state(&fpsimd);
 222
 223         return err ? -EFAULT : 0;
 224 }
 225
 226
 227 struct user_ctxs {
 228         struct fpsimd_context __user *fpsimd;
 229         struct sve_context __user *sve;
 230 };
 231
 232 #ifdef CONFIG_ARM64_SVE
 233
 234 static int preserve_sve_context(struct sve_context __user *ctx)
 235 {
 236         int err = 0;
 237         u16 reserved[ARRAY_SIZE(ctx->__reserved)];
 238         unsigned int vl = current->thread.sve_vl;
 239         unsigned int vq = 0;
 240
 241         if (test_thread_flag(TIF_SVE))
 242                 vq = sve_vq_from_vl(vl);
 243
 244         memset(reserved, 0, sizeof(reserved));
 245
 246         __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
 247         __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
 248                          &ctx->head.size, err);
 249         __put_user_error(vl, &ctx->vl, 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 preserve_fpsimd_context().
 257                  */
 258                 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
 259                                       current->thread.sve_state,
 260                                       SVE_SIG_REGS_SIZE(vq));
 261         }
 262
 263         return err ? -EFAULT : 0;
 264 }
 265
 266 static int restore_sve_fpsimd_context(struct user_ctxs *user)
 267 {
 268         int err;
 269         unsigned int vq;
 270         struct user_fpsimd_state fpsimd;
 271         struct sve_context sve;
 272
 273         if (__copy_from_user(&sve, user->sve, sizeof(sve)))
 274                 return -EFAULT;
 275
 276         if (sve.vl != current->thread.sve_vl)
 277                 return -EINVAL;
 278
 279         if (sve.head.size <= sizeof(*user->sve)) {
 280                 clear_thread_flag(TIF_SVE);
 281                 goto fpsimd_only;
 282         }
 283
 284         vq = sve_vq_from_vl(sve.vl);
 285
 286         if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
 287                 return -EINVAL;
 288
 289         /*
 290          * Careful: we are about __copy_from_user() directly into
 291          * thread.sve_state with preemption enabled, so protection is
 292          * needed to prevent a racing context switch from writing stale
 293          * registers back over the new data.
 294          */
 295
 296         fpsimd_flush_task_state(current);
 297         barrier();
 298         /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */
 299
 300         set_thread_flag(TIF_FOREIGN_FPSTATE);
 301         barrier();
 302         /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
 303
 304         sve_alloc(current);
 305         err = __copy_from_user(current->thread.sve_state,
 306                                (char __user const *)user->sve +
 307                                         SVE_SIG_REGS_OFFSET,
 308                                SVE_SIG_REGS_SIZE(vq));
 309         if (err)
 310                 return -EFAULT;
 311
 312         set_thread_flag(TIF_SVE);
 313
 314 fpsimd_only:
 315         /* copy the FP and status/control registers */
 316         /* restore_sigframe() already checked that user->fpsimd != NULL. */
 317         err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
 318                                sizeof(fpsimd.vregs));
 319         __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
 320         __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
 321
 322         /* load the hardware registers from the fpsimd_state structure */
 323         if (!err)
 324                 fpsimd_update_current_state(&fpsimd);
 325
 326         return err ? -EFAULT : 0;
 327 }
 328
 329 #else /* ! CONFIG_ARM64_SVE */
 330
 331 /* Turn any non-optimised out attempts to use these into a link error: */
 332 extern int preserve_sve_context(void __user *ctx);
 333 extern int restore_sve_fpsimd_context(struct user_ctxs *user);
 334
 335 #endif /* ! CONFIG_ARM64_SVE */
 336
 337
 338 static int parse_user_sigframe(struct user_ctxs *user,
 339                                struct rt_sigframe __user *sf)
 340 {
 341         struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
 342         struct _aarch64_ctx __user *head;
 343         char __user *base = (char __user *)&sc->__reserved;
 344         size_t offset = 0;
 345         size_t limit = sizeof(sc->__reserved);
 346         bool have_extra_context = false;
 347         char const __user *const sfp = (char const __user *)sf;
 348
 349         user->fpsimd = NULL;
 350         user->sve = NULL;
 351
 352         if (!IS_ALIGNED((unsigned long)base, 16))
 353                 goto invalid;
 354
 355         while (1) {
 356                 int err = 0;
 357                 u32 magic, size;
 358                 char const __user *userp;
 359                 struct extra_context const __user *extra;
 360                 u64 extra_datap;
 361                 u32 extra_size;
 362                 struct _aarch64_ctx const __user *end;
 363                 u32 end_magic, end_size;
 364
 365                 if (limit - offset < sizeof(*head))
 366                         goto invalid;
 367
 368                 if (!IS_ALIGNED(offset, 16))
 369                         goto invalid;
 370
 371                 head = (struct _aarch64_ctx __user *)(base + offset);
 372                 __get_user_error(magic, &head->magic, err);
 373                 __get_user_error(size, &head->size, err);
 374                 if (err)
 375                         return err;
 376
 377                 if (limit - offset < size)
 378                         goto invalid;
 379
 380                 switch (magic) {
 381                 case 0:
 382                         if (size)
 383                                 goto invalid;
 384
 385                         goto done;
 386
 387                 case FPSIMD_MAGIC:
 388                         if (user->fpsimd)
 389                                 goto invalid;
 390
 391                         if (size < sizeof(*user->fpsimd))
 392                                 goto invalid;
 393
 394                         user->fpsimd = (struct fpsimd_context __user *)head;
 395                         break;
 396
 397                 case ESR_MAGIC:
 398                         /* ignore */
 399                         break;
 400
 401                 case SVE_MAGIC:
 402                         if (!system_supports_sve())
 403                                 goto invalid;
 404
 405                         if (user->sve)
 406                                 goto invalid;
 407
 408                         if (size < sizeof(*user->sve))
 409                                 goto invalid;
 410
 411                         user->sve = (struct sve_context __user *)head;
 412                         break;
 413
 414                 case EXTRA_MAGIC:
 415                         if (have_extra_context)
 416                                 goto invalid;
 417
 418                         if (size < sizeof(*extra))
 419                                 goto invalid;
 420
 421                         userp = (char const __user *)head;
 422
 423                         extra = (struct extra_context const __user *)userp;
 424                         userp += size;
 425
 426                         __get_user_error(extra_datap, &extra->datap, err);
 427                         __get_user_error(extra_size, &extra->size, err);
 428                         if (err)
 429                                 return err;
 430
 431                         /* Check for the dummy terminator in __reserved[]: */
 432
 433                         if (limit - offset - size < TERMINATOR_SIZE)
 434                                 goto invalid;
 435
 436                         end = (struct _aarch64_ctx const __user *)userp;
 437                         userp += TERMINATOR_SIZE;
 438
 439                         __get_user_error(end_magic, &end->magic, err);
 440                         __get_user_error(end_size, &end->size, err);
 441                         if (err)
 442                                 return err;
 443
 444                         if (end_magic || end_size)
 445                                 goto invalid;
 446
 447                         /* Prevent looping/repeated parsing of extra_context */
 448                         have_extra_context = true;
 449
 450                         base = (__force void __user *)extra_datap;
 451                         if (!IS_ALIGNED((unsigned long)base, 16))
 452                                 goto invalid;
 453
 454                         if (!IS_ALIGNED(extra_size, 16))
 455                                 goto invalid;
 456
 457                         if (base != userp)
 458                                 goto invalid;
 459
 460                         /* Reject "unreasonably large" frames: */
 461                         if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
 462                                 goto invalid;
 463
 464                         /*
 465                          * Ignore trailing terminator in __reserved[]
 466                          * and start parsing extra data:
 467                          */
 468                         offset = 0;
 469                         limit = extra_size;
 470
 471                         if (!access_ok(VERIFY_READ, base, limit))
 472                                 goto invalid;
 473
 474                         continue;
 475
 476                 default:
 477                         goto invalid;
 478                 }
 479
 480                 if (size < sizeof(*head))
 481                         goto invalid;
 482
 483                 if (limit - offset < size)
 484                         goto invalid;
 485
 486                 offset += size;
 487         }
 488
 489 done:
 490         return 0;
 491
 492 invalid:
 493         return -EINVAL;
 494 }
 495
 496 static int restore_sigframe(struct pt_regs *regs,
 497                             struct rt_sigframe __user *sf)
 498 {
 499         sigset_t set;
 500         int i, err;
 501         struct user_ctxs user;
 502
 503         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 504         if (err == 0)
 505                 set_current_blocked(&set);
 506
 507         for (i = 0; i < 31; i++)
 508                 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 509                                  err);
 510         __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 511         __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 512         __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 513
 514         /*
 515          * Avoid sys_rt_sigreturn() restarting.
 516          */
 517         forget_syscall(regs);
 518
 519         err |= !valid_user_regs(&regs->user_regs, current);
 520         if (err == 0)
 521                 err = parse_user_sigframe(&user, sf);
 522
 523         if (err == 0) {
 524                 if (!user.fpsimd)
 525                         return -EINVAL;
 526
 527                 if (user.sve) {
 528                         if (!system_supports_sve())
 529                                 return -EINVAL;
 530
 531                         err = restore_sve_fpsimd_context(&user);
 532                 } else {
 533                         err = restore_fpsimd_context(user.fpsimd);
 534                 }
 535         }
 536
 537         return err;
 538 }
 539
 540 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 541 {
 542         struct rt_sigframe __user *frame;
 543
 544         /* Always make any pending restarted system calls return -EINTR */
 545         current->restart_block.fn = do_no_restart_syscall;
 546
 547         /*
 548          * Since we stacked the signal on a 128-bit boundary, then 'sp' should
 549          * be word aligned here.
 550          */
 551         if (regs->sp & 15)
 552                 goto badframe;
 553
 554         frame = (struct rt_sigframe __user *)regs->sp;
 555
 556         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 557                 goto badframe;
 558
 559         if (restore_sigframe(regs, frame))
 560                 goto badframe;
 561
 562         if (restore_altstack(&frame->uc.uc_stack))
 563                 goto badframe;
 564
 565         return regs->regs[0];
 566
 567 badframe:
 568         if (show_unhandled_signals)
 569                 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
 570                                     current->comm, task_pid_nr(current), __func__,
 571                                     regs->pc, regs->sp);
 572         force_sig(SIGSEGV, current);
 573         return 0;
 574 }
 575
 576 /* Determine the layout of optional records in the signal frame */
 577 static int setup_sigframe_layout(struct rt_sigframe_user_layout *user)
 578 {
 579         int err;
 580
 581         err = sigframe_alloc(user, &user->fpsimd_offset,
 582                              sizeof(struct fpsimd_context));
 583         if (err)
 584                 return err;
 585
 586         /* fault information, if valid */
 587         if (current->thread.fault_code) {
 588                 err = sigframe_alloc(user, &user->esr_offset,
 589                                      sizeof(struct esr_context));
 590                 if (err)
 591                         return err;
 592         }
 593
 594         if (system_supports_sve()) {
 595                 unsigned int vq = 0;
 596
 597                 if (test_thread_flag(TIF_SVE))
 598                         vq = sve_vq_from_vl(current->thread.sve_vl);
 599
 600                 err = sigframe_alloc(user, &user->sve_offset,
 601                                      SVE_SIG_CONTEXT_SIZE(vq));
 602                 if (err)
 603                         return err;
 604         }
 605
 606         return sigframe_alloc_end(user);
 607 }
 608
 609
 610 static int setup_sigframe(struct rt_sigframe_user_layout *user,
 611                           struct pt_regs *regs, sigset_t *set)
 612 {
 613         int i, err = 0;
 614         struct rt_sigframe __user *sf = user->sigframe;
 615
 616         /* set up the stack frame for unwinding */
 617         __put_user_error(regs->regs[29], &user->next_frame->fp, err);
 618         __put_user_error(regs->regs[30], &user->next_frame->lr, err);
 619
 620         for (i = 0; i < 31; i++)
 621                 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 622                                  err);
 623         __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 624         __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 625         __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 626
 627         __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 628
 629         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 630
 631         if (err == 0) {
 632                 struct fpsimd_context __user *fpsimd_ctx =
 633                         apply_user_offset(user, user->fpsimd_offset);
 634                 err |= preserve_fpsimd_context(fpsimd_ctx);
 635         }
 636
 637         /* fault information, if valid */
 638         if (err == 0 && user->esr_offset) {
 639                 struct esr_context __user *esr_ctx =
 640                         apply_user_offset(user, user->esr_offset);
 641
 642                 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
 643                 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
 644                 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
 645         }
 646
 647         /* Scalable Vector Extension state, if present */
 648         if (system_supports_sve() && err == 0 && user->sve_offset) {
 649                 struct sve_context __user *sve_ctx =
 650                         apply_user_offset(user, user->sve_offset);
 651                 err |= preserve_sve_context(sve_ctx);
 652         }
 653
 654         if (err == 0 && user->extra_offset) {
 655                 char __user *sfp = (char __user *)user->sigframe;
 656                 char __user *userp =
 657                         apply_user_offset(user, user->extra_offset);
 658
 659                 struct extra_context __user *extra;
 660                 struct _aarch64_ctx __user *end;
 661                 u64 extra_datap;
 662                 u32 extra_size;
 663
 664                 extra = (struct extra_context __user *)userp;
 665                 userp += EXTRA_CONTEXT_SIZE;
 666
 667                 end = (struct _aarch64_ctx __user *)userp;
 668                 userp += TERMINATOR_SIZE;
 669
 670                 /*
 671                  * extra_datap is just written to the signal frame.
 672                  * The value gets cast back to a void __user *
 673                  * during sigreturn.
 674                  */
 675                 extra_datap = (__force u64)userp;
 676                 extra_size = sfp + round_up(user->size, 16) - userp;
 677
 678                 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
 679                 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
 680                 __put_user_error(extra_datap, &extra->datap, err);
 681                 __put_user_error(extra_size, &extra->size, err);
 682
 683                 /* Add the terminator */
 684                 __put_user_error(0, &end->magic, err);
 685                 __put_user_error(0, &end->size, err);
 686         }
 687
 688         /* set the "end" magic */
 689         if (err == 0) {
 690                 struct _aarch64_ctx __user *end =
 691                         apply_user_offset(user, user->end_offset);
 692
 693                 __put_user_error(0, &end->magic, err);
 694                 __put_user_error(0, &end->size, err);
 695         }
 696
 697         return err;
 698 }
 699
 700 static int get_sigframe(struct rt_sigframe_user_layout *user,
 701                          struct ksignal *ksig, struct pt_regs *regs)
 702 {
 703         unsigned long sp, sp_top;
 704         int err;
 705
 706         init_user_layout(user);
 707         err = setup_sigframe_layout(user);
 708         if (err)
 709                 return err;
 710
 711         sp = sp_top = sigsp(regs->sp, ksig);
 712
 713         sp = round_down(sp - sizeof(struct frame_record), 16);
 714         user->next_frame = (struct frame_record __user *)sp;
 715
 716         sp = round_down(sp, 16) - sigframe_size(user);
 717         user->sigframe = (struct rt_sigframe __user *)sp;
 718
 719         /*
 720          * Check that we can actually write to the signal frame.
 721          */
 722         if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp))
 723                 return -EFAULT;
 724
 725         return 0;
 726 }
 727
 728 static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 729                          struct rt_sigframe_user_layout *user, int usig)
 730 {
 731         __sigrestore_t sigtramp;
 732
 733         regs->regs[0] = usig;
 734         regs->sp = (unsigned long)user->sigframe;
 735         regs->regs[29] = (unsigned long)&user->next_frame->fp;
 736         regs->pc = (unsigned long)ka->sa.sa_handler;
 737
 738         if (ka->sa.sa_flags & SA_RESTORER)
 739                 sigtramp = ka->sa.sa_restorer;
 740         else
 741                 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
 742
 743         regs->regs[30] = (unsigned long)sigtramp;
 744 }
 745
 746 static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
 747                           struct pt_regs *regs)
 748 {
 749         struct rt_sigframe_user_layout user;
 750         struct rt_sigframe __user *frame;
 751         int err = 0;
 752
 753         fpsimd_signal_preserve_current_state();
 754
 755         if (get_sigframe(&user, ksig, regs))
 756                 return 1;
 757
 758         frame = user.sigframe;
 759
 760         __put_user_error(0, &frame->uc.uc_flags, err);
 761         __put_user_error(NULL, &frame->uc.uc_link, err);
 762
 763         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 764         err |= setup_sigframe(&user, regs, set);
 765         if (err == 0) {
 766                 setup_return(regs, &ksig->ka, &user, usig);
 767                 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 768                         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 769                         regs->regs[1] = (unsigned long)&frame->info;
 770                         regs->regs[2] = (unsigned long)&frame->uc;
 771                 }
 772         }
 773
 774         return err;
 775 }
 776
 777 static void setup_restart_syscall(struct pt_regs *regs)
 778 {
 779         if (is_compat_task())
 780                 compat_setup_restart_syscall(regs);
 781         else
 782                 regs->regs[8] = __NR_restart_syscall;
 783 }
 784
 785 /*
 786  * OK, we're invoking a handler
 787  */
 788 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 789 {
 790         struct task_struct *tsk = current;
 791         sigset_t *oldset = sigmask_to_save();
 792         int usig = ksig->sig;
 793         int ret;
 794
 795         /*
 796          * Set up the stack frame
 797          */
 798         if (is_compat_task()) {
 799                 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 800                         ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
 801                 else
 802                         ret = compat_setup_frame(usig, ksig, oldset, regs);
 803         } else {
 804                 ret = setup_rt_frame(usig, ksig, oldset, regs);
 805         }
 806
 807         /*
 808          * Check that the resulting registers are actually sane.
 809          */
 810         ret |= !valid_user_regs(&regs->user_regs, current);
 811
 812         /*
 813          * Fast forward the stepping logic so we step into the signal
 814          * handler.
 815          */
 816         if (!ret)
 817                 user_fastforward_single_step(tsk);
 818
 819         signal_setup_done(ret, ksig, 0);
 820 }
 821
 822 /*
 823  * Note that 'init' is a special process: it doesn't get signals it doesn't
 824  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 825  * mistake.
 826  *
 827  * Note that we go through the signals twice: once to check the signals that
 828  * the kernel can handle, and then we build all the user-level signal handling
 829  * stack-frames in one go after that.
 830  */
 831 static void do_signal(struct pt_regs *regs)
 832 {
 833         unsigned long continue_addr = 0, restart_addr = 0;
 834         int retval = 0;
 835         struct ksignal ksig;
 836
 837         /*
 838          * If we were from a system call, check for system call restarting...
 839          */
 840         if (in_syscall(regs)) {
 841                 continue_addr = regs->pc;
 842                 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
 843                 retval = regs->regs[0];
 844
 845                 /*
 846                  * Avoid additional syscall restarting via ret_to_user.
 847                  */
 848                 forget_syscall(regs);
 849
 850                 /*
 851                  * Prepare for system call restart. We do this here so that a
 852                  * debugger will see the already changed PC.
 853                  */
 854                 switch (retval) {
 855                 case -ERESTARTNOHAND:
 856                 case -ERESTARTSYS:
 857                 case -ERESTARTNOINTR:
 858                 case -ERESTART_RESTARTBLOCK:
 859                         regs->regs[0] = regs->orig_x0;
 860                         regs->pc = restart_addr;
 861                         break;
 862                 }
 863         }
 864
 865         /*
 866          * Get the signal to deliver. When running under ptrace, at this point
 867          * the debugger may change all of our registers.
 868          */
 869         if (get_signal(&ksig)) {
 870                 /*
 871                  * Depending on the signal settings, we may need to revert the
 872                  * decision to restart the system call, but skip this if a
 873                  * debugger has chosen to restart at a different PC.
 874                  */
 875                 if (regs->pc == restart_addr &&
 876                     (retval == -ERESTARTNOHAND ||
 877                      retval == -ERESTART_RESTARTBLOCK ||
 878                      (retval == -ERESTARTSYS &&
 879                       !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
 880                         regs->regs[0] = -EINTR;
 881                         regs->pc = continue_addr;
 882                 }
 883
 884                 handle_signal(&ksig, regs);
 885                 return;
 886         }
 887
 888         /*
 889          * Handle restarting a different system call. As above, if a debugger
 890          * has chosen to restart at a different PC, ignore the restart.
 891          */
 892         if (in_syscall(regs) && regs->pc == restart_addr) {
 893                 if (retval == -ERESTART_RESTARTBLOCK)
 894                         setup_restart_syscall(regs);
 895                 user_rewind_single_step(current);
 896         }
 897
 898         restore_saved_sigmask();
 899 }
 900
 901 asmlinkage void do_notify_resume(struct pt_regs *regs,
 902                                  unsigned int thread_flags)
 903 {
 904         /*
 905          * The assembly code enters us with IRQs off, but it hasn't
 906          * informed the tracing code of that for efficiency reasons.
 907          * Update the trace code with the current status.
 908          */
 909         trace_hardirqs_off();
 910
 911         do {
 912                 /* Check valid user FS if needed */
 913                 addr_limit_user_check();
 914
 915                 if (thread_flags & _TIF_NEED_RESCHED) {
 916                         /* Unmask Debug and SError for the next task */
 917                         local_daif_restore(DAIF_PROCCTX_NOIRQ);
 918
 919                         schedule();
 920                 } else {
 921                         local_daif_restore(DAIF_PROCCTX);
 922
 923                         if (thread_flags & _TIF_UPROBE)
 924                                 uprobe_notify_resume(regs);
 925
 926                         if (thread_flags & _TIF_SIGPENDING)
 927                                 do_signal(regs);
 928
 929                         if (thread_flags & _TIF_NOTIFY_RESUME) {
 930                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 931                                 tracehook_notify_resume(regs);
 932                         }
 933
 934                         if (thread_flags & _TIF_FOREIGN_FPSTATE)
 935                                 fpsimd_restore_current_state();
 936                 }
 937
 938                 local_daif_mask();
 939                 thread_flags = READ_ONCE(current_thread_info()->flags);
 940         } while (thread_flags & _TIF_WORK_MASK);
 941 }