LXR linux/arch/x86/kernel/signal.c

   1/*
   2 *  Copyright (C) 1991, 1992  Linus Torvalds
   3 *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
   4 *
   5 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   6 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   7 *  2000-2002   x86-64 support by Andi Kleen
   8 */
   9
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12#include <linux/sched.h>
  13#include <linux/mm.h>
  14#include <linux/smp.h>
  15#include <linux/kernel.h>
  16#include <linux/errno.h>
  17#include <linux/wait.h>
  18#include <linux/tracehook.h>
  19#include <linux/unistd.h>
  20#include <linux/stddef.h>
  21#include <linux/personality.h>
  22#include <linux/uaccess.h>
  23#include <linux/user-return-notifier.h>
  24#include <linux/uprobes.h>
  25#include <linux/context_tracking.h>
  26
  27#include <asm/processor.h>
  28#include <asm/ucontext.h>
  29#include <asm/fpu/internal.h>
  30#include <asm/fpu/signal.h>
  31#include <asm/vdso.h>
  32#include <asm/mce.h>
  33#include <asm/sighandling.h>
  34#include <asm/vm86.h>
  35
  36#ifdef CONFIG_X86_64
  37#include <asm/proto.h>
  38#include <asm/ia32_unistd.h>
  39#endif /* CONFIG_X86_64 */
  40
  41#include <asm/syscall.h>
  42#include <asm/syscalls.h>
  43
  44#include <asm/sigframe.h>
  45
  46#define COPY(x)                 do {                    \
  47        get_user_ex(regs->x, &sc->x);                   \
  48} while (0)
  49
  50#define GET_SEG(seg)            ({                      \
  51        unsigned short tmp;                             \
  52        get_user_ex(tmp, &sc->seg);                     \
  53        tmp;                                            \
  54})
  55
  56#define COPY_SEG(seg)           do {                    \
  57        regs->seg = GET_SEG(seg);                       \
  58} while (0)
  59
  60#define COPY_SEG_CPL3(seg)      do {                    \
  61        regs->seg = GET_SEG(seg) | 3;                   \
  62} while (0)
  63
  64#ifdef CONFIG_X86_64
  65/*
  66 * If regs->ss will cause an IRET fault, change it.  Otherwise leave it
  67 * alone.  Using this generally makes no sense unless
  68 * user_64bit_mode(regs) would return true.
  69 */
  70static void force_valid_ss(struct pt_regs *regs)
  71{
  72        u32 ar;
  73        asm volatile ("lar %[old_ss], %[ar]\n\t"
  74                      "jz 1f\n\t"               /* If invalid: */
  75                      "xorl %[ar], %[ar]\n\t"   /* set ar = 0 */
  76                      "1:"
  77                      : [ar] "=r" (ar)
  78                      : [old_ss] "rm" ((u16)regs->ss));
  79
  80        /*
  81         * For a valid 64-bit user context, we need DPL 3, type
  82         * read-write data or read-write exp-down data, and S and P
  83         * set.  We can't use VERW because VERW doesn't check the
  84         * P bit.
  85         */
  86        ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
  87        if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
  88            ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
  89                regs->ss = __USER_DS;
  90}
  91#endif
  92
  93static int restore_sigcontext(struct pt_regs *regs,
  94                              struct sigcontext __user *sc,
  95                              unsigned long uc_flags)
  96{
  97        unsigned long buf_val;
  98        void __user *buf;
  99        unsigned int tmpflags;
 100        unsigned int err = 0;
 101
 102        /* Always make any pending restarted system calls return -EINTR */
 103        current->restart_block.fn = do_no_restart_syscall;
 104
 105        get_user_try {
 106
 107#ifdef CONFIG_X86_32
 108                set_user_gs(regs, GET_SEG(gs));
 109                COPY_SEG(fs);
 110                COPY_SEG(es);
 111                COPY_SEG(ds);
 112#endif /* CONFIG_X86_32 */
 113
 114                COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
 115                COPY(dx); COPY(cx); COPY(ip); COPY(ax);
 116
 117#ifdef CONFIG_X86_64
 118                COPY(r8);
 119                COPY(r9);
 120                COPY(r10);
 121                COPY(r11);
 122                COPY(r12);
 123                COPY(r13);
 124                COPY(r14);
 125                COPY(r15);
 126#endif /* CONFIG_X86_64 */
 127
 128                COPY_SEG_CPL3(cs);
 129                COPY_SEG_CPL3(ss);
 130
 131#ifdef CONFIG_X86_64
 132                /*
 133                 * Fix up SS if needed for the benefit of old DOSEMU and
 134                 * CRIU.
 135                 */
 136                if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) &&
 137                             user_64bit_mode(regs)))
 138                        force_valid_ss(regs);
 139#endif
 140
 141                get_user_ex(tmpflags, &sc->flags);
 142                regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 143                regs->orig_ax = -1;             /* disable syscall checks */
 144
 145                get_user_ex(buf_val, &sc->fpstate);
 146                buf = (void __user *)buf_val;
 147        } get_user_catch(err);
 148
 149        err |= fpu__restore_sig(buf, config_enabled(CONFIG_X86_32));
 150
 151        force_iret();
 152
 153        return err;
 154}
 155
 156int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 157                     struct pt_regs *regs, unsigned long mask)
 158{
 159        int err = 0;
 160
 161        put_user_try {
 162
 163#ifdef CONFIG_X86_32
 164                put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
 165                put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
 166                put_user_ex(regs->es, (unsigned int __user *)&sc->es);
 167                put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
 168#endif /* CONFIG_X86_32 */
 169
 170                put_user_ex(regs->di, &sc->di);
 171                put_user_ex(regs->si, &sc->si);
 172                put_user_ex(regs->bp, &sc->bp);
 173                put_user_ex(regs->sp, &sc->sp);
 174                put_user_ex(regs->bx, &sc->bx);
 175                put_user_ex(regs->dx, &sc->dx);
 176                put_user_ex(regs->cx, &sc->cx);
 177                put_user_ex(regs->ax, &sc->ax);
 178#ifdef CONFIG_X86_64
 179                put_user_ex(regs->r8, &sc->r8);
 180                put_user_ex(regs->r9, &sc->r9);
 181                put_user_ex(regs->r10, &sc->r10);
 182                put_user_ex(regs->r11, &sc->r11);
 183                put_user_ex(regs->r12, &sc->r12);
 184                put_user_ex(regs->r13, &sc->r13);
 185                put_user_ex(regs->r14, &sc->r14);
 186                put_user_ex(regs->r15, &sc->r15);
 187#endif /* CONFIG_X86_64 */
 188
 189                put_user_ex(current->thread.trap_nr, &sc->trapno);
 190                put_user_ex(current->thread.error_code, &sc->err);
 191                put_user_ex(regs->ip, &sc->ip);
 192#ifdef CONFIG_X86_32
 193                put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 194                put_user_ex(regs->flags, &sc->flags);
 195                put_user_ex(regs->sp, &sc->sp_at_signal);
 196                put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 197#else /* !CONFIG_X86_32 */
 198                put_user_ex(regs->flags, &sc->flags);
 199                put_user_ex(regs->cs, &sc->cs);
 200                put_user_ex(0, &sc->gs);
 201                put_user_ex(0, &sc->fs);
 202                put_user_ex(regs->ss, &sc->ss);
 203#endif /* CONFIG_X86_32 */
 204
 205                put_user_ex(fpstate, &sc->fpstate);
 206
 207                /* non-iBCS2 extensions.. */
 208                put_user_ex(mask, &sc->oldmask);
 209                put_user_ex(current->thread.cr2, &sc->cr2);
 210        } put_user_catch(err);
 211
 212        return err;
 213}
 214
 215/*
 216 * Set up a signal frame.
 217 */
 218
 219/*
 220 * Determine which stack to use..
 221 */
 222static unsigned long align_sigframe(unsigned long sp)
 223{
 224#ifdef CONFIG_X86_32
 225        /*
 226         * Align the stack pointer according to the i386 ABI,
 227         * i.e. so that on function entry ((sp + 4) & 15) == 0.
 228         */
 229        sp = ((sp + 4) & -16ul) - 4;
 230#else /* !CONFIG_X86_32 */
 231        sp = round_down(sp, 16) - 8;
 232#endif
 233        return sp;
 234}
 235
 236static void __user *
 237get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 238             void __user **fpstate)
 239{
 240        /* Default to using normal stack */
 241        unsigned long math_size = 0;
 242        unsigned long sp = regs->sp;
 243        unsigned long buf_fx = 0;
 244        int onsigstack = on_sig_stack(sp);
 245        struct fpu *fpu = &current->thread.fpu;
 246
 247        /* redzone */
 248        if (config_enabled(CONFIG_X86_64))
 249                sp -= 128;
 250
 251        if (!onsigstack) {
 252                /* This is the X/Open sanctioned signal stack switching.  */
 253                if (ka->sa.sa_flags & SA_ONSTACK) {
 254                        if (current->sas_ss_size)
 255                                sp = current->sas_ss_sp + current->sas_ss_size;
 256                } else if (config_enabled(CONFIG_X86_32) &&
 257                           (regs->ss & 0xffff) != __USER_DS &&
 258                           !(ka->sa.sa_flags & SA_RESTORER) &&
 259                           ka->sa.sa_restorer) {
 260                                /* This is the legacy signal stack switching. */
 261                                sp = (unsigned long) ka->sa.sa_restorer;
 262                }
 263        }
 264
 265        if (fpu->fpstate_active) {
 266                sp = fpu__alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
 267                                          &buf_fx, &math_size);
 268                *fpstate = (void __user *)sp;
 269        }
 270
 271        sp = align_sigframe(sp - frame_size);
 272
 273        /*
 274         * If we are on the alternate signal stack and would overflow it, don't.
 275         * Return an always-bogus address instead so we will die with SIGSEGV.
 276         */
 277        if (onsigstack && !likely(on_sig_stack(sp)))
 278                return (void __user *)-1L;
 279
 280        /* save i387 and extended state */
 281        if (fpu->fpstate_active &&
 282            copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
 283                return (void __user *)-1L;
 284
 285        return (void __user *)sp;
 286}
 287
 288#ifdef CONFIG_X86_32
 289static const struct {
 290        u16 poplmovl;
 291        u32 val;
 292        u16 int80;
 293} __attribute__((packed)) retcode = {
 294        0xb858,         /* popl %eax; movl $..., %eax */
 295        __NR_sigreturn,
 296        0x80cd,         /* int $0x80 */
 297};
 298
 299static const struct {
 300        u8  movl;
 301        u32 val;
 302        u16 int80;
 303        u8  pad;
 304} __attribute__((packed)) rt_retcode = {
 305        0xb8,           /* movl $..., %eax */
 306        __NR_rt_sigreturn,
 307        0x80cd,         /* int $0x80 */
 308        0
 309};
 310
 311static int
 312__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
 313              struct pt_regs *regs)
 314{
 315        struct sigframe __user *frame;
 316        void __user *restorer;
 317        int err = 0;
 318        void __user *fpstate = NULL;
 319
 320        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 321
 322        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 323                return -EFAULT;
 324
 325        if (__put_user(sig, &frame->sig))
 326                return -EFAULT;
 327
 328        if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 329                return -EFAULT;
 330
 331        if (_NSIG_WORDS > 1) {
 332                if (__copy_to_user(&frame->extramask, &set->sig[1],
 333                                   sizeof(frame->extramask)))
 334                        return -EFAULT;
 335        }
 336
 337        if (current->mm->context.vdso)
 338                restorer = current->mm->context.vdso +
 339                        vdso_image_32.sym___kernel_sigreturn;
 340        else
 341                restorer = &frame->retcode;
 342        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 343                restorer = ksig->ka.sa.sa_restorer;
 344
 345        /* Set up to return from userspace.  */
 346        err |= __put_user(restorer, &frame->pretcode);
 347
 348        /*
 349         * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 350         *
 351         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 352         * reasons and because gdb uses it as a signature to notice
 353         * signal handler stack frames.
 354         */
 355        err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 356
 357        if (err)
 358                return -EFAULT;
 359
 360        /* Set up registers for signal handler */
 361        regs->sp = (unsigned long)frame;
 362        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 363        regs->ax = (unsigned long)sig;
 364        regs->dx = 0;
 365        regs->cx = 0;
 366
 367        regs->ds = __USER_DS;
 368        regs->es = __USER_DS;
 369        regs->ss = __USER_DS;
 370        regs->cs = __USER_CS;
 371
 372        return 0;
 373}
 374
 375static int __setup_rt_frame(int sig, struct ksignal *ksig,
 376                            sigset_t *set, struct pt_regs *regs)
 377{
 378        struct rt_sigframe __user *frame;
 379        void __user *restorer;
 380        int err = 0;
 381        void __user *fpstate = NULL;
 382
 383        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 384
 385        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 386                return -EFAULT;
 387
 388        put_user_try {
 389                put_user_ex(sig, &frame->sig);
 390                put_user_ex(&frame->info, &frame->pinfo);
 391                put_user_ex(&frame->uc, &frame->puc);
 392
 393                /* Create the ucontext.  */
 394                if (cpu_has_xsave)
 395                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 396                else
 397                        put_user_ex(0, &frame->uc.uc_flags);
 398                put_user_ex(0, &frame->uc.uc_link);
 399                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 400
 401                /* Set up to return from userspace.  */
 402                restorer = current->mm->context.vdso +
 403                        vdso_image_32.sym___kernel_rt_sigreturn;
 404                if (ksig->ka.sa.sa_flags & SA_RESTORER)
 405                        restorer = ksig->ka.sa.sa_restorer;
 406                put_user_ex(restorer, &frame->pretcode);
 407
 408                /*
 409                 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 410                 *
 411                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 412                 * reasons and because gdb uses it as a signature to notice
 413                 * signal handler stack frames.
 414                 */
 415                put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 416        } put_user_catch(err);
 417        
 418        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 419        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 420                                regs, set->sig[0]);
 421        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 422
 423        if (err)
 424                return -EFAULT;
 425
 426        /* Set up registers for signal handler */
 427        regs->sp = (unsigned long)frame;
 428        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 429        regs->ax = (unsigned long)sig;
 430        regs->dx = (unsigned long)&frame->info;
 431        regs->cx = (unsigned long)&frame->uc;
 432
 433        regs->ds = __USER_DS;
 434        regs->es = __USER_DS;
 435        regs->ss = __USER_DS;
 436        regs->cs = __USER_CS;
 437
 438        return 0;
 439}
 440#else /* !CONFIG_X86_32 */
 441static unsigned long frame_uc_flags(struct pt_regs *regs)
 442{
 443        unsigned long flags;
 444
 445        if (cpu_has_xsave)
 446                flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
 447        else
 448                flags = UC_SIGCONTEXT_SS;
 449
 450        if (likely(user_64bit_mode(regs)))
 451                flags |= UC_STRICT_RESTORE_SS;
 452
 453        return flags;
 454}
 455
 456static int __setup_rt_frame(int sig, struct ksignal *ksig,
 457                            sigset_t *set, struct pt_regs *regs)
 458{
 459        struct rt_sigframe __user *frame;
 460        void __user *fp = NULL;
 461        int err = 0;
 462
 463        frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 464
 465        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 466                return -EFAULT;
 467
 468        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 469                if (copy_siginfo_to_user(&frame->info, &ksig->info))
 470                        return -EFAULT;
 471        }
 472
 473        put_user_try {
 474                /* Create the ucontext.  */
 475                put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
 476                put_user_ex(0, &frame->uc.uc_link);
 477                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 478
 479                /* Set up to return from userspace.  If provided, use a stub
 480                   already in userspace.  */
 481                /* x86-64 should always use SA_RESTORER. */
 482                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 483                        put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
 484                } else {
 485                        /* could use a vstub here */
 486                        err |= -EFAULT;
 487                }
 488        } put_user_catch(err);
 489
 490        err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 491        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 492
 493        if (err)
 494                return -EFAULT;
 495
 496        /* Set up registers for signal handler */
 497        regs->di = sig;
 498        /* In case the signal handler was declared without prototypes */
 499        regs->ax = 0;
 500
 501        /* This also works for non SA_SIGINFO handlers because they expect the
 502           next argument after the signal number on the stack. */
 503        regs->si = (unsigned long)&frame->info;
 504        regs->dx = (unsigned long)&frame->uc;
 505        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 506
 507        regs->sp = (unsigned long)frame;
 508
 509        /*
 510         * Set up the CS and SS registers to run signal handlers in
 511         * 64-bit mode, even if the handler happens to be interrupting
 512         * 32-bit or 16-bit code.
 513         *
 514         * SS is subtle.  In 64-bit mode, we don't need any particular
 515         * SS descriptor, but we do need SS to be valid.  It's possible
 516         * that the old SS is entirely bogus -- this can happen if the
 517         * signal we're trying to deliver is #GP or #SS caused by a bad
 518         * SS value.  We also have a compatbility issue here: DOSEMU
 519         * relies on the contents of the SS register indicating the
 520         * SS value at the time of the signal, even though that code in
 521         * DOSEMU predates sigreturn's ability to restore SS.  (DOSEMU
 522         * avoids relying on sigreturn to restore SS; instead it uses
 523         * a trampoline.)  So we do our best: if the old SS was valid,
 524         * we keep it.  Otherwise we replace it.
 525         */
 526        regs->cs = __USER_CS;
 527
 528        if (unlikely(regs->ss != __USER_DS))
 529                force_valid_ss(regs);
 530
 531        return 0;
 532}
 533#endif /* CONFIG_X86_32 */
 534
 535static int x32_setup_rt_frame(struct ksignal *ksig,
 536                              compat_sigset_t *set,
 537                              struct pt_regs *regs)
 538{
 539#ifdef CONFIG_X86_X32_ABI
 540        struct rt_sigframe_x32 __user *frame;
 541        void __user *restorer;
 542        int err = 0;
 543        void __user *fpstate = NULL;
 544
 545        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 546
 547        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 548                return -EFAULT;
 549
 550        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 551                if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 552                        return -EFAULT;
 553        }
 554
 555        put_user_try {
 556                /* Create the ucontext.  */
 557                put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags);
 558                put_user_ex(0, &frame->uc.uc_link);
 559                compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 560                put_user_ex(0, &frame->uc.uc__pad0);
 561
 562                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 563                        restorer = ksig->ka.sa.sa_restorer;
 564                } else {
 565                        /* could use a vstub here */
 566                        restorer = NULL;
 567                        err |= -EFAULT;
 568                }
 569                put_user_ex(restorer, &frame->pretcode);
 570        } put_user_catch(err);
 571
 572        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 573                                regs, set->sig[0]);
 574        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 575
 576        if (err)
 577                return -EFAULT;
 578
 579        /* Set up registers for signal handler */
 580        regs->sp = (unsigned long) frame;
 581        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 582
 583        /* We use the x32 calling convention here... */
 584        regs->di = ksig->sig;
 585        regs->si = (unsigned long) &frame->info;
 586        regs->dx = (unsigned long) &frame->uc;
 587
 588        loadsegment(ds, __USER_DS);
 589        loadsegment(es, __USER_DS);
 590
 591        regs->cs = __USER_CS;
 592        regs->ss = __USER_DS;
 593#endif  /* CONFIG_X86_X32_ABI */
 594
 595        return 0;
 596}
 597
 598/*
 599 * Do a signal return; undo the signal stack.
 600 */
 601#ifdef CONFIG_X86_32
 602asmlinkage unsigned long sys_sigreturn(void)
 603{
 604        struct pt_regs *regs = current_pt_regs();
 605        struct sigframe __user *frame;
 606        sigset_t set;
 607
 608        frame = (struct sigframe __user *)(regs->sp - 8);
 609
 610        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 611                goto badframe;
 612        if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 613                && __copy_from_user(&set.sig[1], &frame->extramask,
 614                                    sizeof(frame->extramask))))
 615                goto badframe;
 616
 617        set_current_blocked(&set);
 618
 619        /*
 620         * x86_32 has no uc_flags bits relevant to restore_sigcontext.
 621         * Save a few cycles by skipping the __get_user.
 622         */
 623        if (restore_sigcontext(regs, &frame->sc, 0))
 624                goto badframe;
 625        return regs->ax;
 626
 627badframe:
 628        signal_fault(regs, frame, "sigreturn");
 629
 630        return 0;
 631}
 632#endif /* CONFIG_X86_32 */
 633
 634asmlinkage long sys_rt_sigreturn(void)
 635{
 636        struct pt_regs *regs = current_pt_regs();
 637        struct rt_sigframe __user *frame;
 638        sigset_t set;
 639        unsigned long uc_flags;
 640
 641        frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 642        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 643                goto badframe;
 644        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 645                goto badframe;
 646        if (__get_user(uc_flags, &frame->uc.uc_flags))
 647                goto badframe;
 648
 649        set_current_blocked(&set);
 650
 651        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
 652                goto badframe;
 653
 654        if (restore_altstack(&frame->uc.uc_stack))
 655                goto badframe;
 656
 657        return regs->ax;
 658
 659badframe:
 660        signal_fault(regs, frame, "rt_sigreturn");
 661        return 0;
 662}
 663
 664static inline int is_ia32_compat_frame(void)
 665{
 666        return config_enabled(CONFIG_IA32_EMULATION) &&
 667               test_thread_flag(TIF_IA32);
 668}
 669
 670static inline int is_ia32_frame(void)
 671{
 672        return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame();
 673}
 674
 675static inline int is_x32_frame(void)
 676{
 677        return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
 678}
 679
 680static int
 681setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 682{
 683        int usig = ksig->sig;
 684        sigset_t *set = sigmask_to_save();
 685        compat_sigset_t *cset = (compat_sigset_t *) set;
 686
 687        /* Set up the stack frame */
 688        if (is_ia32_frame()) {
 689                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 690                        return ia32_setup_rt_frame(usig, ksig, cset, regs);
 691                else
 692                        return ia32_setup_frame(usig, ksig, cset, regs);
 693        } else if (is_x32_frame()) {
 694                return x32_setup_rt_frame(ksig, cset, regs);
 695        } else {
 696                return __setup_rt_frame(ksig->sig, ksig, set, regs);
 697        }
 698}
 699
 700static void
 701handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 702{
 703        bool stepping, failed;
 704        struct fpu *fpu = &current->thread.fpu;
 705
 706        if (v8086_mode(regs))
 707                save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
 708
 709        /* Are we from a system call? */
 710        if (syscall_get_nr(current, regs) >= 0) {
 711                /* If so, check system call restarting.. */
 712                switch (syscall_get_error(current, regs)) {
 713                case -ERESTART_RESTARTBLOCK:
 714                case -ERESTARTNOHAND:
 715                        regs->ax = -EINTR;
 716                        break;
 717
 718                case -ERESTARTSYS:
 719                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 720                                regs->ax = -EINTR;
 721                                break;
 722                        }
 723                /* fallthrough */
 724                case -ERESTARTNOINTR:
 725                        regs->ax = regs->orig_ax;
 726                        regs->ip -= 2;
 727                        break;
 728                }
 729        }
 730
 731        /*
 732         * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
 733         * so that register information in the sigcontext is correct and
 734         * then notify the tracer before entering the signal handler.
 735         */
 736        stepping = test_thread_flag(TIF_SINGLESTEP);
 737        if (stepping)
 738                user_disable_single_step(current);
 739
 740        failed = (setup_rt_frame(ksig, regs) < 0);
 741        if (!failed) {
 742                /*
 743                 * Clear the direction flag as per the ABI for function entry.
 744                 *
 745                 * Clear RF when entering the signal handler, because
 746                 * it might disable possible debug exception from the
 747                 * signal handler.
 748                 *
 749                 * Clear TF for the case when it wasn't set by debugger to
 750                 * avoid the recursive send_sigtrap() in SIGTRAP handler.
 751                 */
 752                regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
 753                /*
 754                 * Ensure the signal handler starts with the new fpu state.
 755                 */
 756                if (fpu->fpstate_active)
 757                        fpu__clear(fpu);
 758        }
 759        signal_setup_done(failed, ksig, stepping);
 760}
 761
 762static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
 763{
 764#ifdef CONFIG_X86_64
 765        if (is_ia32_task())
 766                return __NR_ia32_restart_syscall;
 767#endif
 768#ifdef CONFIG_X86_X32_ABI
 769        return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
 770#else
 771        return __NR_restart_syscall;
 772#endif
 773}
 774
 775/*
 776 * Note that 'init' is a special process: it doesn't get signals it doesn't
 777 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 778 * mistake.
 779 */
 780void do_signal(struct pt_regs *regs)
 781{
 782        struct ksignal ksig;
 783
 784        if (get_signal(&ksig)) {
 785                /* Whee! Actually deliver the signal.  */
 786                handle_signal(&ksig, regs);
 787                return;
 788        }
 789
 790        /* Did we come from a system call? */
 791        if (syscall_get_nr(current, regs) >= 0) {
 792                /* Restart the system call - no handlers present */
 793                switch (syscall_get_error(current, regs)) {
 794                case -ERESTARTNOHAND:
 795                case -ERESTARTSYS:
 796                case -ERESTARTNOINTR:
 797                        regs->ax = regs->orig_ax;
 798                        regs->ip -= 2;
 799                        break;
 800
 801                case -ERESTART_RESTARTBLOCK:
 802                        regs->ax = get_nr_restart_syscall(regs);
 803                        regs->ip -= 2;
 804                        break;
 805                }
 806        }
 807
 808        /*
 809         * If there's no signal to deliver, we just put the saved sigmask
 810         * back.
 811         */
 812        restore_saved_sigmask();
 813}
 814
 815void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 816{
 817        struct task_struct *me = current;
 818
 819        if (show_unhandled_signals && printk_ratelimit()) {
 820                printk("%s"
 821                       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 822                       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 823                       me->comm, me->pid, where, frame,
 824                       regs->ip, regs->sp, regs->orig_ax);
 825                print_vma_addr(" in ", regs->ip);
 826                pr_cont("\n");
 827        }
 828
 829        force_sig(SIGSEGV, me);
 830}
 831
 832#ifdef CONFIG_X86_X32_ABI
 833asmlinkage long sys32_x32_rt_sigreturn(void)
 834{
 835        struct pt_regs *regs = current_pt_regs();
 836        struct rt_sigframe_x32 __user *frame;
 837        sigset_t set;
 838        unsigned long uc_flags;
 839
 840        frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 841
 842        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 843                goto badframe;
 844        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 845                goto badframe;
 846        if (__get_user(uc_flags, &frame->uc.uc_flags))
 847                goto badframe;
 848
 849        set_current_blocked(&set);
 850
 851        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
 852                goto badframe;
 853
 854        if (compat_restore_altstack(&frame->uc.uc_stack))
 855                goto badframe;
 856
 857        return regs->ax;
 858
 859badframe:
 860        signal_fault(regs, frame, "x32 rt_sigreturn");
 861        return 0;
 862}
 863#endif
 864