linux/arch/arm64/kernel/signal.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Based on arch/arm/kernel/signal.c
   4 *
   5 * Copyright (C) 1995-2009 Russell King
   6 * Copyright (C) 2012 ARM Ltd.
   7 */
   8
   9#include <linux/cache.h>
  10#include <linux/compat.h>
  11#include <linux/errno.h>
  12#include <linux/kernel.h>
  13#include <linux/signal.h>
  14#include <linux/freezer.h>
  15#include <linux/stddef.h>
  16#include <linux/uaccess.h>
  17#include <linux/sizes.h>
  18#include <linux/string.h>
  19#include <linux/resume_user_mode.h>
  20#include <linux/ratelimit.h>
  21#include <linux/syscalls.h>
  22
  23#include <asm/daifflags.h>
  24#include <asm/debug-monitors.h>
  25#include <asm/elf.h>
  26#include <asm/cacheflush.h>
  27#include <asm/ucontext.h>
  28#include <asm/unistd.h>
  29#include <asm/fpsimd.h>
  30#include <asm/ptrace.h>
  31#include <asm/syscall.h>
  32#include <asm/signal32.h>
  33#include <asm/traps.h>
  34#include <asm/vdso.h>
  35
  36/*
  37 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
  38 */
  39struct rt_sigframe {
  40        struct siginfo info;
  41        struct ucontext uc;
  42};
  43
  44struct frame_record {
  45        u64 fp;
  46        u64 lr;
  47};
  48
  49struct rt_sigframe_user_layout {
  50        struct rt_sigframe __user *sigframe;
  51        struct frame_record __user *next_frame;
  52
  53        unsigned long size;     /* size of allocated sigframe data */
  54        unsigned long limit;    /* largest allowed size */
  55
  56        unsigned long fpsimd_offset;
  57        unsigned long esr_offset;
  58        unsigned long sve_offset;
  59        unsigned long za_offset;
  60        unsigned long extra_offset;
  61        unsigned long end_offset;
  62};
  63
  64#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
  65#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
  66#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
  67
  68static void init_user_layout(struct rt_sigframe_user_layout *user)
  69{
  70        const size_t reserved_size =
  71                sizeof(user->sigframe->uc.uc_mcontext.__reserved);
  72
  73        memset(user, 0, sizeof(*user));
  74        user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
  75
  76        user->limit = user->size + reserved_size;
  77
  78        user->limit -= TERMINATOR_SIZE;
  79        user->limit -= EXTRA_CONTEXT_SIZE;
  80        /* Reserve space for extension and terminator ^ */
  81}
  82
  83static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
  84{
  85        return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
  86}
  87
  88/*
  89 * Sanity limit on the approximate maximum size of signal frame we'll
  90 * try to generate.  Stack alignment padding and the frame record are
  91 * not taken into account.  This limit is not a guarantee and is
  92 * NOT ABI.
  93 */
  94#define SIGFRAME_MAXSZ SZ_256K
  95
  96static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
  97                            unsigned long *offset, size_t size, bool extend)
  98{
  99        size_t padded_size = round_up(size, 16);
 100
 101        if (padded_size > user->limit - user->size &&
 102            !user->extra_offset &&
 103            extend) {
 104                int ret;
 105
 106                user->limit += EXTRA_CONTEXT_SIZE;
 107                ret = __sigframe_alloc(user, &user->extra_offset,
 108                                       sizeof(struct extra_context), false);
 109                if (ret) {
 110                        user->limit -= EXTRA_CONTEXT_SIZE;
 111                        return ret;
 112                }
 113
 114                /* Reserve space for the __reserved[] terminator */
 115                user->size += TERMINATOR_SIZE;
 116
 117                /*
 118                 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
 119                 * the terminator:
 120                 */
 121                user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
 122        }
 123
 124        /* Still not enough space?  Bad luck! */
 125        if (padded_size > user->limit - user->size)
 126                return -ENOMEM;
 127
 128        *offset = user->size;
 129        user->size += padded_size;
 130
 131        return 0;
 132}
 133
 134/*
 135 * Allocate space for an optional record of <size> bytes in the user
 136 * signal frame.  The offset from the signal frame base address to the
 137 * allocated block is assigned to *offset.
 138 */
 139static int sigframe_alloc(struct rt_sigframe_user_layout *user,
 140                          unsigned long *offset, size_t size)
 141{
 142        return __sigframe_alloc(user, offset, size, true);
 143}
 144
 145/* Allocate the null terminator record and prevent further allocations */
 146static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
 147{
 148        int ret;
 149
 150        /* Un-reserve the space reserved for the terminator: */
 151        user->limit += TERMINATOR_SIZE;
 152
 153        ret = sigframe_alloc(user, &user->end_offset,
 154                             sizeof(struct _aarch64_ctx));
 155        if (ret)
 156                return ret;
 157
 158        /* Prevent further allocation: */
 159        user->limit = user->size;
 160        return 0;
 161}
 162
 163static void __user *apply_user_offset(
 164        struct rt_sigframe_user_layout const *user, unsigned long offset)
 165{
 166        char __user *base = (char __user *)user->sigframe;
 167
 168        return base + offset;
 169}
 170
 171static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
 172{
 173        struct user_fpsimd_state const *fpsimd =
 174                &current->thread.uw.fpsimd_state;
 175        int err;
 176
 177        /* copy the FP and status/control registers */
 178        err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
 179        __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
 180        __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
 181
 182        /* copy the magic/size information */
 183        __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
 184        __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
 185
 186        return err ? -EFAULT : 0;
 187}
 188
 189static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
 190{
 191        struct user_fpsimd_state fpsimd;
 192        __u32 magic, size;
 193        int err = 0;
 194
 195        /* check the magic/size information */
 196        __get_user_error(magic, &ctx->head.magic, err);
 197        __get_user_error(size, &ctx->head.size, err);
 198        if (err)
 199                return -EFAULT;
 200        if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
 201                return -EINVAL;
 202
 203        /* copy the FP and status/control registers */
 204        err = __copy_from_user(fpsimd.vregs, ctx->vregs,
 205                               sizeof(fpsimd.vregs));
 206        __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
 207        __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
 208
 209        clear_thread_flag(TIF_SVE);
 210
 211        /* load the hardware registers from the fpsimd_state structure */
 212        if (!err)
 213                fpsimd_update_current_state(&fpsimd);
 214
 215        return err ? -EFAULT : 0;
 216}
 217
 218
 219struct user_ctxs {
 220        struct fpsimd_context __user *fpsimd;
 221        struct sve_context __user *sve;
 222        struct za_context __user *za;
 223};
 224
 225#ifdef CONFIG_ARM64_SVE
 226
 227static int preserve_sve_context(struct sve_context __user *ctx)
 228{
 229        int err = 0;
 230        u16 reserved[ARRAY_SIZE(ctx->__reserved)];
 231        u16 flags = 0;
 232        unsigned int vl = task_get_sve_vl(current);
 233        unsigned int vq = 0;
 234
 235        if (thread_sm_enabled(&current->thread)) {
 236                vl = task_get_sme_vl(current);
 237                vq = sve_vq_from_vl(vl);
 238                flags |= SVE_SIG_FLAG_SM;
 239        } else if (test_thread_flag(TIF_SVE)) {
 240                vq = sve_vq_from_vl(vl);
 241        }
 242
 243        memset(reserved, 0, sizeof(reserved));
 244
 245        __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
 246        __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
 247                         &ctx->head.size, err);
 248        __put_user_error(vl, &ctx->vl, err);
 249        __put_user_error(flags, &ctx->flags, err);
 250        BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
 251        err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
 252
 253        if (vq) {
 254                /*
 255                 * This assumes that the SVE state has already been saved to
 256                 * the task struct by calling the function
 257                 * fpsimd_signal_preserve_current_state().
 258                 */
 259                err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
 260                                      current->thread.sve_state,
 261                                      SVE_SIG_REGS_SIZE(vq));
 262        }
 263
 264        return err ? -EFAULT : 0;
 265}
 266
 267static int restore_sve_fpsimd_context(struct user_ctxs *user)
 268{
 269        int err;
 270        unsigned int vl, vq;
 271        struct user_fpsimd_state fpsimd;
 272        struct sve_context sve;
 273
 274        if (__copy_from_user(&sve, user->sve, sizeof(sve)))
 275                return -EFAULT;
 276
 277        if (sve.flags & SVE_SIG_FLAG_SM) {
 278                if (!system_supports_sme())
 279                        return -EINVAL;
 280
 281                vl = task_get_sme_vl(current);
 282        } else {
 283                if (!system_supports_sve())
 284                        return -EINVAL;
 285
 286                vl = task_get_sve_vl(current);
 287        }
 288
 289        if (sve.vl != vl)
 290                return -EINVAL;
 291
 292        if (sve.head.size <= sizeof(*user->sve)) {
 293                clear_thread_flag(TIF_SVE);
 294                current->thread.svcr &= ~SVCR_SM_MASK;
 295                goto fpsimd_only;
 296        }
 297
 298        vq = sve_vq_from_vl(sve.vl);
 299
 300        if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
 301                return -EINVAL;
 302
 303        /*
 304         * Careful: we are about __copy_from_user() directly into
 305         * thread.sve_state with preemption enabled, so protection is
 306         * needed to prevent a racing context switch from writing stale
 307         * registers back over the new data.
 308         */
 309
 310        fpsimd_flush_task_state(current);
 311        /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
 312
 313        sve_alloc(current, true);
 314        if (!current->thread.sve_state) {
 315                clear_thread_flag(TIF_SVE);
 316                return -ENOMEM;
 317        }
 318
 319        err = __copy_from_user(current->thread.sve_state,
 320                               (char __user const *)user->sve +
 321                                        SVE_SIG_REGS_OFFSET,
 322                               SVE_SIG_REGS_SIZE(vq));
 323        if (err)
 324                return -EFAULT;
 325
 326        if (sve.flags & SVE_SIG_FLAG_SM)
 327                current->thread.svcr |= SVCR_SM_MASK;
 328        else
 329                set_thread_flag(TIF_SVE);
 330
 331fpsimd_only:
 332        /* copy the FP and status/control registers */
 333        /* restore_sigframe() already checked that user->fpsimd != NULL. */
 334        err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
 335                               sizeof(fpsimd.vregs));
 336        __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
 337        __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
 338
 339        /* load the hardware registers from the fpsimd_state structure */
 340        if (!err)
 341                fpsimd_update_current_state(&fpsimd);
 342
 343        return err ? -EFAULT : 0;
 344}
 345
 346#else /* ! CONFIG_ARM64_SVE */
 347
 348static int restore_sve_fpsimd_context(struct user_ctxs *user)
 349{
 350        WARN_ON_ONCE(1);
 351        return -EINVAL;
 352}
 353
 354/* Turn any non-optimised out attempts to use this into a link error: */
 355extern int preserve_sve_context(void __user *ctx);
 356
 357#endif /* ! CONFIG_ARM64_SVE */
 358
 359#ifdef CONFIG_ARM64_SME
 360
 361static int preserve_za_context(struct za_context __user *ctx)
 362{
 363        int err = 0;
 364        u16 reserved[ARRAY_SIZE(ctx->__reserved)];
 365        unsigned int vl = task_get_sme_vl(current);
 366        unsigned int vq;
 367
 368        if (thread_za_enabled(&current->thread))
 369                vq = sve_vq_from_vl(vl);
 370        else
 371                vq = 0;
 372
 373        memset(reserved, 0, sizeof(reserved));
 374
 375        __put_user_error(ZA_MAGIC, &ctx->head.magic, err);
 376        __put_user_error(round_up(ZA_SIG_CONTEXT_SIZE(vq), 16),
 377                         &ctx->head.size, err);
 378        __put_user_error(vl, &ctx->vl, err);
 379        BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
 380        err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
 381
 382        if (vq) {
 383                /*
 384                 * This assumes that the ZA state has already been saved to
 385                 * the task struct by calling the function
 386                 * fpsimd_signal_preserve_current_state().
 387                 */
 388                err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET,
 389                                      current->thread.za_state,
 390                                      ZA_SIG_REGS_SIZE(vq));
 391        }
 392
 393        return err ? -EFAULT : 0;
 394}
 395
 396static int restore_za_context(struct user_ctxs *user)
 397{
 398        int err;
 399        unsigned int vq;
 400        struct za_context za;
 401
 402        if (__copy_from_user(&za, user->za, sizeof(za)))
 403                return -EFAULT;
 404
 405        if (za.vl != task_get_sme_vl(current))
 406                return -EINVAL;
 407
 408        if (za.head.size <= sizeof(*user->za)) {
 409                current->thread.svcr &= ~SVCR_ZA_MASK;
 410                return 0;
 411        }
 412
 413        vq = sve_vq_from_vl(za.vl);
 414
 415        if (za.head.size < ZA_SIG_CONTEXT_SIZE(vq))
 416                return -EINVAL;
 417
 418        /*
 419         * Careful: we are about __copy_from_user() directly into
 420         * thread.za_state with preemption enabled, so protection is
 421         * needed to prevent a racing context switch from writing stale
 422         * registers back over the new data.
 423         */
 424
 425        fpsimd_flush_task_state(current);
 426        /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
 427
 428        sme_alloc(current);
 429        if (!current->thread.za_state) {
 430                current->thread.svcr &= ~SVCR_ZA_MASK;
 431                clear_thread_flag(TIF_SME);
 432                return -ENOMEM;
 433        }
 434
 435        err = __copy_from_user(current->thread.za_state,
 436                               (char __user const *)user->za +
 437                                        ZA_SIG_REGS_OFFSET,
 438                               ZA_SIG_REGS_SIZE(vq));
 439        if (err)
 440                return -EFAULT;
 441
 442        set_thread_flag(TIF_SME);
 443        current->thread.svcr |= SVCR_ZA_MASK;
 444
 445        return 0;
 446}
 447#else /* ! CONFIG_ARM64_SME */
 448
 449/* Turn any non-optimised out attempts to use these into a link error: */
 450extern int preserve_za_context(void __user *ctx);
 451extern int restore_za_context(struct user_ctxs *user);
 452
 453#endif /* ! CONFIG_ARM64_SME */
 454
 455static int parse_user_sigframe(struct user_ctxs *user,
 456                               struct rt_sigframe __user *sf)
 457{
 458        struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
 459        struct _aarch64_ctx __user *head;
 460        char __user *base = (char __user *)&sc->__reserved;
 461        size_t offset = 0;
 462        size_t limit = sizeof(sc->__reserved);
 463        bool have_extra_context = false;
 464        char const __user *const sfp = (char const __user *)sf;
 465
 466        user->fpsimd = NULL;
 467        user->sve = NULL;
 468        user->za = NULL;
 469
 470        if (!IS_ALIGNED((unsigned long)base, 16))
 471                goto invalid;
 472
 473        while (1) {
 474                int err = 0;
 475                u32 magic, size;
 476                char const __user *userp;
 477                struct extra_context const __user *extra;
 478                u64 extra_datap;
 479                u32 extra_size;
 480                struct _aarch64_ctx const __user *end;
 481                u32 end_magic, end_size;
 482
 483                if (limit - offset < sizeof(*head))
 484                        goto invalid;
 485
 486                if (!IS_ALIGNED(offset, 16))
 487                        goto invalid;
 488
 489                head = (struct _aarch64_ctx __user *)(base + offset);
 490                __get_user_error(magic, &head->magic, err);
 491                __get_user_error(size, &head->size, err);
 492                if (err)
 493                        return err;
 494
 495                if (limit - offset < size)
 496                        goto invalid;
 497
 498                switch (magic) {
 499                case 0:
 500                        if (size)
 501                                goto invalid;
 502
 503                        goto done;
 504
 505                case FPSIMD_MAGIC:
 506                        if (!system_supports_fpsimd())
 507                                goto invalid;
 508                        if (user->fpsimd)
 509                                goto invalid;
 510
 511                        if (size < sizeof(*user->fpsimd))
 512                                goto invalid;
 513
 514                        user->fpsimd = (struct fpsimd_context __user *)head;
 515                        break;
 516
 517                case ESR_MAGIC:
 518                        /* ignore */
 519                        break;
 520
 521                case SVE_MAGIC:
 522                        if (!system_supports_sve() && !system_supports_sme())
 523                                goto invalid;
 524
 525                        if (user->sve)
 526                                goto invalid;
 527
 528                        if (size < sizeof(*user->sve))
 529                                goto invalid;
 530
 531                        user->sve = (struct sve_context __user *)head;
 532                        break;
 533
 534                case ZA_MAGIC:
 535                        if (!system_supports_sme())
 536                                goto invalid;
 537
 538                        if (user->za)
 539                                goto invalid;
 540
 541                        if (size < sizeof(*user->za))
 542                                goto invalid;
 543
 544                        user->za = (struct za_context __user *)head;
 545                        break;
 546
 547                case EXTRA_MAGIC:
 548                        if (have_extra_context)
 549                                goto invalid;
 550
 551                        if (size < sizeof(*extra))
 552                                goto invalid;
 553
 554                        userp = (char const __user *)head;
 555
 556                        extra = (struct extra_context const __user *)userp;
 557                        userp += size;
 558
 559                        __get_user_error(extra_datap, &extra->datap, err);
 560                        __get_user_error(extra_size, &extra->size, err);
 561                        if (err)
 562                                return err;
 563
 564                        /* Check for the dummy terminator in __reserved[]: */
 565
 566                        if (limit - offset - size < TERMINATOR_SIZE)
 567                                goto invalid;
 568
 569                        end = (struct _aarch64_ctx const __user *)userp;
 570                        userp += TERMINATOR_SIZE;
 571
 572                        __get_user_error(end_magic, &end->magic, err);
 573                        __get_user_error(end_size, &end->size, err);
 574                        if (err)
 575                                return err;
 576
 577                        if (end_magic || end_size)
 578                                goto invalid;
 579
 580                        /* Prevent looping/repeated parsing of extra_context */
 581                        have_extra_context = true;
 582
 583                        base = (__force void __user *)extra_datap;
 584                        if (!IS_ALIGNED((unsigned long)base, 16))
 585                                goto invalid;
 586
 587                        if (!IS_ALIGNED(extra_size, 16))
 588                                goto invalid;
 589
 590                        if (base != userp)
 591                                goto invalid;
 592
 593                        /* Reject "unreasonably large" frames: */
 594                        if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
 595                                goto invalid;
 596
 597                        /*
 598                         * Ignore trailing terminator in __reserved[]
 599                         * and start parsing extra data:
 600                         */
 601                        offset = 0;
 602                        limit = extra_size;
 603
 604                        if (!access_ok(base, limit))
 605                                goto invalid;
 606
 607                        continue;
 608
 609                default:
 610                        goto invalid;
 611                }
 612
 613                if (size < sizeof(*head))
 614                        goto invalid;
 615
 616                if (limit - offset < size)
 617                        goto invalid;
 618
 619                offset += size;
 620        }
 621
 622done:
 623        return 0;
 624
 625invalid:
 626        return -EINVAL;
 627}
 628
 629static int restore_sigframe(struct pt_regs *regs,
 630                            struct rt_sigframe __user *sf)
 631{
 632        sigset_t set;
 633        int i, err;
 634        struct user_ctxs user;
 635
 636        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 637        if (err == 0)
 638                set_current_blocked(&set);
 639
 640        for (i = 0; i < 31; i++)
 641                __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 642                                 err);
 643        __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 644        __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 645        __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 646
 647        /*
 648         * Avoid sys_rt_sigreturn() restarting.
 649         */
 650        forget_syscall(regs);
 651
 652        err |= !valid_user_regs(&regs->user_regs, current);
 653        if (err == 0)
 654                err = parse_user_sigframe(&user, sf);
 655
 656        if (err == 0 && system_supports_fpsimd()) {
 657                if (!user.fpsimd)
 658                        return -EINVAL;
 659
 660                if (user.sve)
 661                        err = restore_sve_fpsimd_context(&user);
 662                else
 663                        err = restore_fpsimd_context(user.fpsimd);
 664        }
 665
 666        if (err == 0 && system_supports_sme() && user.za)
 667                err = restore_za_context(&user);
 668
 669        return err;
 670}
 671
 672SYSCALL_DEFINE0(rt_sigreturn)
 673{
 674        struct pt_regs *regs = current_pt_regs();
 675        struct rt_sigframe __user *frame;
 676
 677        /* Always make any pending restarted system calls return -EINTR */
 678        current->restart_block.fn = do_no_restart_syscall;
 679
 680        /*
 681         * Since we stacked the signal on a 128-bit boundary, then 'sp' should
 682         * be word aligned here.
 683         */
 684        if (regs->sp & 15)
 685                goto badframe;
 686
 687        frame = (struct rt_sigframe __user *)regs->sp;
 688
 689        if (!access_ok(frame, sizeof (*frame)))
 690                goto badframe;
 691
 692        if (restore_sigframe(regs, frame))
 693                goto badframe;
 694
 695        if (restore_altstack(&frame->uc.uc_stack))
 696                goto badframe;
 697
 698        return regs->regs[0];
 699
 700badframe:
 701        arm64_notify_segfault(regs->sp);
 702        return 0;
 703}
 704
 705/*
 706 * Determine the layout of optional records in the signal frame
 707 *
 708 * add_all: if true, lays out the biggest possible signal frame for
 709 *      this task; otherwise, generates a layout for the current state
 710 *      of the task.
 711 */
 712static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
 713                                 bool add_all)
 714{
 715        int err;
 716
 717        if (system_supports_fpsimd()) {
 718                err = sigframe_alloc(user, &user->fpsimd_offset,
 719                                     sizeof(struct fpsimd_context));
 720                if (err)
 721                        return err;
 722        }
 723
 724        /* fault information, if valid */
 725        if (add_all || current->thread.fault_code) {
 726                err = sigframe_alloc(user, &user->esr_offset,
 727                                     sizeof(struct esr_context));
 728                if (err)
 729                        return err;
 730        }
 731
 732        if (system_supports_sve()) {
 733                unsigned int vq = 0;
 734
 735                if (add_all || test_thread_flag(TIF_SVE) ||
 736                    thread_sm_enabled(&current->thread)) {
 737                        int vl = max(sve_max_vl(), sme_max_vl());
 738
 739                        if (!add_all)
 740                                vl = thread_get_cur_vl(&current->thread);
 741
 742                        vq = sve_vq_from_vl(vl);
 743                }
 744
 745                err = sigframe_alloc(user, &user->sve_offset,
 746                                     SVE_SIG_CONTEXT_SIZE(vq));
 747                if (err)
 748                        return err;
 749        }
 750
 751        if (system_supports_sme()) {
 752                unsigned int vl;
 753                unsigned int vq = 0;
 754
 755                if (add_all)
 756                        vl = sme_max_vl();
 757                else
 758                        vl = task_get_sme_vl(current);
 759
 760                if (thread_za_enabled(&current->thread))
 761                        vq = sve_vq_from_vl(vl);
 762
 763                err = sigframe_alloc(user, &user->za_offset,
 764                                     ZA_SIG_CONTEXT_SIZE(vq));
 765                if (err)
 766                        return err;
 767        }
 768
 769        return sigframe_alloc_end(user);
 770}
 771
 772static int setup_sigframe(struct rt_sigframe_user_layout *user,
 773                          struct pt_regs *regs, sigset_t *set)
 774{
 775        int i, err = 0;
 776        struct rt_sigframe __user *sf = user->sigframe;
 777
 778        /* set up the stack frame for unwinding */
 779        __put_user_error(regs->regs[29], &user->next_frame->fp, err);
 780        __put_user_error(regs->regs[30], &user->next_frame->lr, err);
 781
 782        for (i = 0; i < 31; i++)
 783                __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 784                                 err);
 785        __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
 786        __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
 787        __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
 788
 789        __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 790
 791        err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 792
 793        if (err == 0 && system_supports_fpsimd()) {
 794                struct fpsimd_context __user *fpsimd_ctx =
 795                        apply_user_offset(user, user->fpsimd_offset);
 796                err |= preserve_fpsimd_context(fpsimd_ctx);
 797        }
 798
 799        /* fault information, if valid */
 800        if (err == 0 && user->esr_offset) {
 801                struct esr_context __user *esr_ctx =
 802                        apply_user_offset(user, user->esr_offset);
 803
 804                __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
 805                __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
 806                __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
 807        }
 808
 809        /* Scalable Vector Extension state (including streaming), if present */
 810        if ((system_supports_sve() || system_supports_sme()) &&
 811            err == 0 && user->sve_offset) {
 812                struct sve_context __user *sve_ctx =
 813                        apply_user_offset(user, user->sve_offset);
 814                err |= preserve_sve_context(sve_ctx);
 815        }
 816
 817        /* ZA state if present */
 818        if (system_supports_sme() && err == 0 && user->za_offset) {
 819                struct za_context __user *za_ctx =
 820                        apply_user_offset(user, user->za_offset);
 821                err |= preserve_za_context(za_ctx);
 822        }
 823
 824        if (err == 0 && user->extra_offset) {
 825                char __user *sfp = (char __user *)user->sigframe;
 826                char __user *userp =
 827                        apply_user_offset(user, user->extra_offset);
 828
 829                struct extra_context __user *extra;
 830                struct _aarch64_ctx __user *end;
 831                u64 extra_datap;
 832                u32 extra_size;
 833
 834                extra = (struct extra_context __user *)userp;
 835                userp += EXTRA_CONTEXT_SIZE;
 836
 837                end = (struct _aarch64_ctx __user *)userp;
 838                userp += TERMINATOR_SIZE;
 839
 840                /*
 841                 * extra_datap is just written to the signal frame.
 842                 * The value gets cast back to a void __user *
 843                 * during sigreturn.
 844                 */
 845                extra_datap = (__force u64)userp;
 846                extra_size = sfp + round_up(user->size, 16) - userp;
 847
 848                __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
 849                __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
 850                __put_user_error(extra_datap, &extra->datap, err);
 851                __put_user_error(extra_size, &extra->size, err);
 852
 853                /* Add the terminator */
 854                __put_user_error(0, &end->magic, err);
 855                __put_user_error(0, &end->size, err);
 856        }
 857
 858        /* set the "end" magic */
 859        if (err == 0) {
 860                struct _aarch64_ctx __user *end =
 861                        apply_user_offset(user, user->end_offset);
 862
 863                __put_user_error(0, &end->magic, err);
 864                __put_user_error(0, &end->size, err);
 865        }
 866
 867        return err;
 868}
 869
 870static int get_sigframe(struct rt_sigframe_user_layout *user,
 871                         struct ksignal *ksig, struct pt_regs *regs)
 872{
 873        unsigned long sp, sp_top;
 874        int err;
 875
 876        init_user_layout(user);
 877        err = setup_sigframe_layout(user, false);
 878        if (err)
 879                return err;
 880
 881        sp = sp_top = sigsp(regs->sp, ksig);
 882
 883        sp = round_down(sp - sizeof(struct frame_record), 16);
 884        user->next_frame = (struct frame_record __user *)sp;
 885
 886        sp = round_down(sp, 16) - sigframe_size(user);
 887        user->sigframe = (struct rt_sigframe __user *)sp;
 888
 889        /*
 890         * Check that we can actually write to the signal frame.
 891         */
 892        if (!access_ok(user->sigframe, sp_top - sp))
 893                return -EFAULT;
 894
 895        return 0;
 896}
 897
 898static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 899                         struct rt_sigframe_user_layout *user, int usig)
 900{
 901        __sigrestore_t sigtramp;
 902
 903        regs->regs[0] = usig;
 904        regs->sp = (unsigned long)user->sigframe;
 905        regs->regs[29] = (unsigned long)&user->next_frame->fp;
 906        regs->pc = (unsigned long)ka->sa.sa_handler;
 907
 908        /*
 909         * Signal delivery is a (wacky) indirect function call in
 910         * userspace, so simulate the same setting of BTYPE as a BLR
 911         * <register containing the signal handler entry point>.
 912         * Signal delivery to a location in a PROT_BTI guarded page
 913         * that is not a function entry point will now trigger a
 914         * SIGILL in userspace.
 915         *
 916         * If the signal handler entry point is not in a PROT_BTI
 917         * guarded page, this is harmless.
 918         */
 919        if (system_supports_bti()) {
 920                regs->pstate &= ~PSR_BTYPE_MASK;
 921                regs->pstate |= PSR_BTYPE_C;
 922        }
 923
 924        /* TCO (Tag Check Override) always cleared for signal handlers */
 925        regs->pstate &= ~PSR_TCO_BIT;
 926
 927        /* Signal handlers are invoked with ZA and streaming mode disabled */
 928        if (system_supports_sme()) {
 929                /*
 930                 * If we were in streaming mode the saved register
 931                 * state was SVE but we will exit SM and use the
 932                 * FPSIMD register state - flush the saved FPSIMD
 933                 * register state in case it gets loaded.
 934                 */
 935                if (current->thread.svcr & SVCR_SM_MASK)
 936                        memset(&current->thread.uw.fpsimd_state, 0,
 937                               sizeof(current->thread.uw.fpsimd_state));
 938
 939                current->thread.svcr &= ~(SVCR_ZA_MASK |
 940                                          SVCR_SM_MASK);
 941                sme_smstop();
 942        }
 943
 944        if (ka->sa.sa_flags & SA_RESTORER)
 945                sigtramp = ka->sa.sa_restorer;
 946        else
 947                sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
 948
 949        regs->regs[30] = (unsigned long)sigtramp;
 950}
 951
 952static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
 953                          struct pt_regs *regs)
 954{
 955        struct rt_sigframe_user_layout user;
 956        struct rt_sigframe __user *frame;
 957        int err = 0;
 958
 959        fpsimd_signal_preserve_current_state();
 960
 961        if (get_sigframe(&user, ksig, regs))
 962                return 1;
 963
 964        frame = user.sigframe;
 965
 966        __put_user_error(0, &frame->uc.uc_flags, err);
 967        __put_user_error(NULL, &frame->uc.uc_link, err);
 968
 969        err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 970        err |= setup_sigframe(&user, regs, set);
 971        if (err == 0) {
 972                setup_return(regs, &ksig->ka, &user, usig);
 973                if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 974                        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 975                        regs->regs[1] = (unsigned long)&frame->info;
 976                        regs->regs[2] = (unsigned long)&frame->uc;
 977                }
 978        }
 979
 980        return err;
 981}
 982
 983static void setup_restart_syscall(struct pt_regs *regs)
 984{
 985        if (is_compat_task())
 986                compat_setup_restart_syscall(regs);
 987        else
 988                regs->regs[8] = __NR_restart_syscall;
 989}
 990
 991/*
 992 * OK, we're invoking a handler
 993 */
 994static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 995{
 996        sigset_t *oldset = sigmask_to_save();
 997        int usig = ksig->sig;
 998        int ret;
 999
1000        rseq_signal_deliver(ksig, regs);
1001
1002        /*
1003         * Set up the stack frame
1004         */
1005        if (is_compat_task()) {
1006                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
1007                        ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
1008                else
1009                        ret = compat_setup_frame(usig, ksig, oldset, regs);
1010        } else {
1011                ret = setup_rt_frame(usig, ksig, oldset, regs);
1012        }
1013
1014        /*
1015         * Check that the resulting registers are actually sane.
1016         */
1017        ret |= !valid_user_regs(&regs->user_regs, current);
1018
1019        /* Step into the signal handler if we are stepping */
1020        signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
1021}
1022
1023/*
1024 * Note that 'init' is a special process: it doesn't get signals it doesn't
1025 * want to handle. Thus you cannot kill init even with a SIGKILL even by
1026 * mistake.
1027 *
1028 * Note that we go through the signals twice: once to check the signals that
1029 * the kernel can handle, and then we build all the user-level signal handling
1030 * stack-frames in one go after that.
1031 */
1032static void do_signal(struct pt_regs *regs)
1033{
1034        unsigned long continue_addr = 0, restart_addr = 0;
1035        int retval = 0;
1036        struct ksignal ksig;
1037        bool syscall = in_syscall(regs);
1038
1039        /*
1040         * If we were from a system call, check for system call restarting...
1041         */
1042        if (syscall) {
1043                continue_addr = regs->pc;
1044                restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
1045                retval = regs->regs[0];
1046
1047                /*
1048                 * Avoid additional syscall restarting via ret_to_user.
1049                 */
1050                forget_syscall(regs);
1051
1052                /*
1053                 * Prepare for system call restart. We do this here so that a
1054                 * debugger will see the already changed PC.
1055                 */
1056                switch (retval) {
1057                case -ERESTARTNOHAND:
1058                case -ERESTARTSYS:
1059                case -ERESTARTNOINTR:
1060                case -ERESTART_RESTARTBLOCK:
1061                        regs->regs[0] = regs->orig_x0;
1062                        regs->pc = restart_addr;
1063                        break;
1064                }
1065        }
1066
1067        /*
1068         * Get the signal to deliver. When running under ptrace, at this point
1069         * the debugger may change all of our registers.
1070         */
1071        if (get_signal(&ksig)) {
1072                /*
1073                 * Depending on the signal settings, we may need to revert the
1074                 * decision to restart the system call, but skip this if a
1075                 * debugger has chosen to restart at a different PC.
1076                 */
1077                if (regs->pc == restart_addr &&
1078                    (retval == -ERESTARTNOHAND ||
1079                     retval == -ERESTART_RESTARTBLOCK ||
1080                     (retval == -ERESTARTSYS &&
1081                      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
1082                        syscall_set_return_value(current, regs, -EINTR, 0);
1083                        regs->pc = continue_addr;
1084                }
1085
1086                handle_signal(&ksig, regs);
1087                return;
1088        }
1089
1090        /*
1091         * Handle restarting a different system call. As above, if a debugger
1092         * has chosen to restart at a different PC, ignore the restart.
1093         */
1094        if (syscall && regs->pc == restart_addr) {
1095                if (retval == -ERESTART_RESTARTBLOCK)
1096                        setup_restart_syscall(regs);
1097                user_rewind_single_step(current);
1098        }
1099
1100        restore_saved_sigmask();
1101}
1102
1103void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
1104{
1105        do {
1106                if (thread_flags & _TIF_NEED_RESCHED) {
1107                        /* Unmask Debug and SError for the next task */
1108                        local_daif_restore(DAIF_PROCCTX_NOIRQ);
1109
1110                        schedule();
1111                } else {
1112                        local_daif_restore(DAIF_PROCCTX);
1113
1114                        if (thread_flags & _TIF_UPROBE)
1115                                uprobe_notify_resume(regs);
1116
1117                        if (thread_flags & _TIF_MTE_ASYNC_FAULT) {
1118                                clear_thread_flag(TIF_MTE_ASYNC_FAULT);
1119                                send_sig_fault(SIGSEGV, SEGV_MTEAERR,
1120                                               (void __user *)NULL, current);
1121                        }
1122
1123                        if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
1124                                do_signal(regs);
1125
1126                        if (thread_flags & _TIF_NOTIFY_RESUME)
1127                                resume_user_mode_work(regs);
1128
1129                        if (thread_flags & _TIF_FOREIGN_FPSTATE)
1130                                fpsimd_restore_current_state();
1131                }
1132
1133                local_daif_mask();
1134                thread_flags = read_thread_flags();
1135        } while (thread_flags & _TIF_WORK_MASK);
1136}
1137
1138unsigned long __ro_after_init signal_minsigstksz;
1139
1140/*
1141 * Determine the stack space required for guaranteed signal devliery.
1142 * This function is used to populate AT_MINSIGSTKSZ at process startup.
1143 * cpufeatures setup is assumed to be complete.
1144 */
1145void __init minsigstksz_setup(void)
1146{
1147        struct rt_sigframe_user_layout user;
1148
1149        init_user_layout(&user);
1150
1151        /*
1152         * If this fails, SIGFRAME_MAXSZ needs to be enlarged.  It won't
1153         * be big enough, but it's our best guess:
1154         */
1155        if (WARN_ON(setup_sigframe_layout(&user, true)))
1156                return;
1157
1158        signal_minsigstksz = sigframe_size(&user) +
1159                round_up(sizeof(struct frame_record), 16) +
1160                16; /* max alignment padding */
1161}
1162
1163/*
1164 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
1165 * changes likely come with new fields that should be added below.
1166 */
1167static_assert(NSIGILL   == 11);
1168static_assert(NSIGFPE   == 15);
1169static_assert(NSIGSEGV  == 9);
1170static_assert(NSIGBUS   == 5);
1171static_assert(NSIGTRAP  == 6);
1172static_assert(NSIGCHLD  == 6);
1173static_assert(NSIGSYS   == 2);
1174static_assert(sizeof(siginfo_t) == 128);
1175static_assert(__alignof__(siginfo_t) == 8);
1176static_assert(offsetof(siginfo_t, si_signo)     == 0x00);
1177static_assert(offsetof(siginfo_t, si_errno)     == 0x04);
1178static_assert(offsetof(siginfo_t, si_code)      == 0x08);
1179static_assert(offsetof(siginfo_t, si_pid)       == 0x10);
1180static_assert(offsetof(siginfo_t, si_uid)       == 0x14);
1181static_assert(offsetof(siginfo_t, si_tid)       == 0x10);
1182static_assert(offsetof(siginfo_t, si_overrun)   == 0x14);
1183static_assert(offsetof(siginfo_t, si_status)    == 0x18);
1184static_assert(offsetof(siginfo_t, si_utime)     == 0x20);
1185static_assert(offsetof(siginfo_t, si_stime)     == 0x28);
1186static_assert(offsetof(siginfo_t, si_value)     == 0x18);
1187static_assert(offsetof(siginfo_t, si_int)       == 0x18);
1188static_assert(offsetof(siginfo_t, si_ptr)       == 0x18);
1189static_assert(offsetof(siginfo_t, si_addr)      == 0x10);
1190static_assert(offsetof(siginfo_t, si_addr_lsb)  == 0x18);
1191static_assert(offsetof(siginfo_t, si_lower)     == 0x20);
1192static_assert(offsetof(siginfo_t, si_upper)     == 0x28);
1193static_assert(offsetof(siginfo_t, si_pkey)      == 0x20);
1194static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
1195static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
1196static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
1197static_assert(offsetof(siginfo_t, si_band)      == 0x10);
1198static_assert(offsetof(siginfo_t, si_fd)        == 0x18);
1199static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
1200static_assert(offsetof(siginfo_t, si_syscall)   == 0x18);
1201static_assert(offsetof(siginfo_t, si_arch)      == 0x1c);
1202