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
  64int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  65{
  66        void __user *buf;
  67        unsigned int tmpflags;
  68        unsigned int err = 0;
  69
  70        /* Always make any pending restarted system calls return -EINTR */
  71        current->restart_block.fn = do_no_restart_syscall;
  72
  73        get_user_try {
  74
  75#ifdef CONFIG_X86_32
  76                set_user_gs(regs, GET_SEG(gs));
  77                COPY_SEG(fs);
  78                COPY_SEG(es);
  79                COPY_SEG(ds);
  80#endif /* CONFIG_X86_32 */
  81
  82                COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  83                COPY(dx); COPY(cx); COPY(ip); COPY(ax);
  84
  85#ifdef CONFIG_X86_64
  86                COPY(r8);
  87                COPY(r9);
  88                COPY(r10);
  89                COPY(r11);
  90                COPY(r12);
  91                COPY(r13);
  92                COPY(r14);
  93                COPY(r15);
  94#endif /* CONFIG_X86_64 */
  95
  96#ifdef CONFIG_X86_32
  97                COPY_SEG_CPL3(cs);
  98                COPY_SEG_CPL3(ss);
  99#else /* !CONFIG_X86_32 */
 100                /* Kernel saves and restores only the CS segment register on signals,
 101                 * which is the bare minimum needed to allow mixed 32/64-bit code.
 102                 * App's signal handler can save/restore other segments if needed. */
 103                COPY_SEG_CPL3(cs);
 104#endif /* CONFIG_X86_32 */
 105
 106                get_user_ex(tmpflags, &sc->flags);
 107                regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 108                regs->orig_ax = -1;             /* disable syscall checks */
 109
 110                get_user_ex(buf, &sc->fpstate);
 111        } get_user_catch(err);
 112
 113        err |= fpu__restore_sig(buf, config_enabled(CONFIG_X86_32));
 114
 115        force_iret();
 116
 117        return err;
 118}
 119
 120int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 121                     struct pt_regs *regs, unsigned long mask)
 122{
 123        int err = 0;
 124
 125        put_user_try {
 126
 127#ifdef CONFIG_X86_32
 128                put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
 129                put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
 130                put_user_ex(regs->es, (unsigned int __user *)&sc->es);
 131                put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
 132#endif /* CONFIG_X86_32 */
 133
 134                put_user_ex(regs->di, &sc->di);
 135                put_user_ex(regs->si, &sc->si);
 136                put_user_ex(regs->bp, &sc->bp);
 137                put_user_ex(regs->sp, &sc->sp);
 138                put_user_ex(regs->bx, &sc->bx);
 139                put_user_ex(regs->dx, &sc->dx);
 140                put_user_ex(regs->cx, &sc->cx);
 141                put_user_ex(regs->ax, &sc->ax);
 142#ifdef CONFIG_X86_64
 143                put_user_ex(regs->r8, &sc->r8);
 144                put_user_ex(regs->r9, &sc->r9);
 145                put_user_ex(regs->r10, &sc->r10);
 146                put_user_ex(regs->r11, &sc->r11);
 147                put_user_ex(regs->r12, &sc->r12);
 148                put_user_ex(regs->r13, &sc->r13);
 149                put_user_ex(regs->r14, &sc->r14);
 150                put_user_ex(regs->r15, &sc->r15);
 151#endif /* CONFIG_X86_64 */
 152
 153                put_user_ex(current->thread.trap_nr, &sc->trapno);
 154                put_user_ex(current->thread.error_code, &sc->err);
 155                put_user_ex(regs->ip, &sc->ip);
 156#ifdef CONFIG_X86_32
 157                put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 158                put_user_ex(regs->flags, &sc->flags);
 159                put_user_ex(regs->sp, &sc->sp_at_signal);
 160                put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 161#else /* !CONFIG_X86_32 */
 162                put_user_ex(regs->flags, &sc->flags);
 163                put_user_ex(regs->cs, &sc->cs);
 164                put_user_ex(0, &sc->gs);
 165                put_user_ex(0, &sc->fs);
 166#endif /* CONFIG_X86_32 */
 167
 168                put_user_ex(fpstate, &sc->fpstate);
 169
 170                /* non-iBCS2 extensions.. */
 171                put_user_ex(mask, &sc->oldmask);
 172                put_user_ex(current->thread.cr2, &sc->cr2);
 173        } put_user_catch(err);
 174
 175        return err;
 176}
 177
 178/*
 179 * Set up a signal frame.
 180 */
 181
 182/*
 183 * Determine which stack to use..
 184 */
 185static unsigned long align_sigframe(unsigned long sp)
 186{
 187#ifdef CONFIG_X86_32
 188        /*
 189         * Align the stack pointer according to the i386 ABI,
 190         * i.e. so that on function entry ((sp + 4) & 15) == 0.
 191         */
 192        sp = ((sp + 4) & -16ul) - 4;
 193#else /* !CONFIG_X86_32 */
 194        sp = round_down(sp, 16) - 8;
 195#endif
 196        return sp;
 197}
 198
 199static inline void __user *
 200get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 201             void __user **fpstate)
 202{
 203        /* Default to using normal stack */
 204        unsigned long math_size = 0;
 205        unsigned long sp = regs->sp;
 206        unsigned long buf_fx = 0;
 207        int onsigstack = on_sig_stack(sp);
 208        struct fpu *fpu = &current->thread.fpu;
 209
 210        /* redzone */
 211        if (config_enabled(CONFIG_X86_64))
 212                sp -= 128;
 213
 214        if (!onsigstack) {
 215                /* This is the X/Open sanctioned signal stack switching.  */
 216                if (ka->sa.sa_flags & SA_ONSTACK) {
 217                        if (current->sas_ss_size)
 218                                sp = current->sas_ss_sp + current->sas_ss_size;
 219                } else if (config_enabled(CONFIG_X86_32) &&
 220                           (regs->ss & 0xffff) != __USER_DS &&
 221                           !(ka->sa.sa_flags & SA_RESTORER) &&
 222                           ka->sa.sa_restorer) {
 223                                /* This is the legacy signal stack switching. */
 224                                sp = (unsigned long) ka->sa.sa_restorer;
 225                }
 226        }
 227
 228        if (fpu->fpstate_active) {
 229                sp = fpu__alloc_mathframe(sp, config_enabled(CONFIG_X86_32),
 230                                          &buf_fx, &math_size);
 231                *fpstate = (void __user *)sp;
 232        }
 233
 234        sp = align_sigframe(sp - frame_size);
 235
 236        /*
 237         * If we are on the alternate signal stack and would overflow it, don't.
 238         * Return an always-bogus address instead so we will die with SIGSEGV.
 239         */
 240        if (onsigstack && !likely(on_sig_stack(sp)))
 241                return (void __user *)-1L;
 242
 243        /* save i387 and extended state */
 244        if (fpu->fpstate_active &&
 245            copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
 246                return (void __user *)-1L;
 247
 248        return (void __user *)sp;
 249}
 250
 251#ifdef CONFIG_X86_32
 252static const struct {
 253        u16 poplmovl;
 254        u32 val;
 255        u16 int80;
 256} __attribute__((packed)) retcode = {
 257        0xb858,         /* popl %eax; movl $..., %eax */
 258        __NR_sigreturn,
 259        0x80cd,         /* int $0x80 */
 260};
 261
 262static const struct {
 263        u8  movl;
 264        u32 val;
 265        u16 int80;
 266        u8  pad;
 267} __attribute__((packed)) rt_retcode = {
 268        0xb8,           /* movl $..., %eax */
 269        __NR_rt_sigreturn,
 270        0x80cd,         /* int $0x80 */
 271        0
 272};
 273
 274static int
 275__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
 276              struct pt_regs *regs)
 277{
 278        struct sigframe __user *frame;
 279        void __user *restorer;
 280        int err = 0;
 281        void __user *fpstate = NULL;
 282
 283        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 284
 285        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 286                return -EFAULT;
 287
 288        if (__put_user(sig, &frame->sig))
 289                return -EFAULT;
 290
 291        if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 292                return -EFAULT;
 293
 294        if (_NSIG_WORDS > 1) {
 295                if (__copy_to_user(&frame->extramask, &set->sig[1],
 296                                   sizeof(frame->extramask)))
 297                        return -EFAULT;
 298        }
 299
 300        if (current->mm->context.vdso)
 301                restorer = current->mm->context.vdso +
 302                        selected_vdso32->sym___kernel_sigreturn;
 303        else
 304                restorer = &frame->retcode;
 305        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 306                restorer = ksig->ka.sa.sa_restorer;
 307
 308        /* Set up to return from userspace.  */
 309        err |= __put_user(restorer, &frame->pretcode);
 310
 311        /*
 312         * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 313         *
 314         * WE DO NOT USE IT ANY MORE! It's only left here for historical
 315         * reasons and because gdb uses it as a signature to notice
 316         * signal handler stack frames.
 317         */
 318        err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 319
 320        if (err)
 321                return -EFAULT;
 322
 323        /* Set up registers for signal handler */
 324        regs->sp = (unsigned long)frame;
 325        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 326        regs->ax = (unsigned long)sig;
 327        regs->dx = 0;
 328        regs->cx = 0;
 329
 330        regs->ds = __USER_DS;
 331        regs->es = __USER_DS;
 332        regs->ss = __USER_DS;
 333        regs->cs = __USER_CS;
 334
 335        return 0;
 336}
 337
 338static int __setup_rt_frame(int sig, struct ksignal *ksig,
 339                            sigset_t *set, struct pt_regs *regs)
 340{
 341        struct rt_sigframe __user *frame;
 342        void __user *restorer;
 343        int err = 0;
 344        void __user *fpstate = NULL;
 345
 346        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 347
 348        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 349                return -EFAULT;
 350
 351        put_user_try {
 352                put_user_ex(sig, &frame->sig);
 353                put_user_ex(&frame->info, &frame->pinfo);
 354                put_user_ex(&frame->uc, &frame->puc);
 355
 356                /* Create the ucontext.  */
 357                if (cpu_has_xsave)
 358                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 359                else
 360                        put_user_ex(0, &frame->uc.uc_flags);
 361                put_user_ex(0, &frame->uc.uc_link);
 362                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 363
 364                /* Set up to return from userspace.  */
 365                restorer = current->mm->context.vdso +
 366                        selected_vdso32->sym___kernel_rt_sigreturn;
 367                if (ksig->ka.sa.sa_flags & SA_RESTORER)
 368                        restorer = ksig->ka.sa.sa_restorer;
 369                put_user_ex(restorer, &frame->pretcode);
 370
 371                /*
 372                 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 373                 *
 374                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 375                 * reasons and because gdb uses it as a signature to notice
 376                 * signal handler stack frames.
 377                 */
 378                put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 379        } put_user_catch(err);
 380        
 381        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 382        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 383                                regs, set->sig[0]);
 384        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 385
 386        if (err)
 387                return -EFAULT;
 388
 389        /* Set up registers for signal handler */
 390        regs->sp = (unsigned long)frame;
 391        regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
 392        regs->ax = (unsigned long)sig;
 393        regs->dx = (unsigned long)&frame->info;
 394        regs->cx = (unsigned long)&frame->uc;
 395
 396        regs->ds = __USER_DS;
 397        regs->es = __USER_DS;
 398        regs->ss = __USER_DS;
 399        regs->cs = __USER_CS;
 400
 401        return 0;
 402}
 403#else /* !CONFIG_X86_32 */
 404static int __setup_rt_frame(int sig, struct ksignal *ksig,
 405                            sigset_t *set, struct pt_regs *regs)
 406{
 407        struct rt_sigframe __user *frame;
 408        void __user *fp = NULL;
 409        int err = 0;
 410
 411        frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
 412
 413        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 414                return -EFAULT;
 415
 416        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 417                if (copy_siginfo_to_user(&frame->info, &ksig->info))
 418                        return -EFAULT;
 419        }
 420
 421        put_user_try {
 422                /* Create the ucontext.  */
 423                if (cpu_has_xsave)
 424                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 425                else
 426                        put_user_ex(0, &frame->uc.uc_flags);
 427                put_user_ex(0, &frame->uc.uc_link);
 428                save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 429
 430                /* Set up to return from userspace.  If provided, use a stub
 431                   already in userspace.  */
 432                /* x86-64 should always use SA_RESTORER. */
 433                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 434                        put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
 435                } else {
 436                        /* could use a vstub here */
 437                        err |= -EFAULT;
 438                }
 439        } put_user_catch(err);
 440
 441        err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 442        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 443
 444        if (err)
 445                return -EFAULT;
 446
 447        /* Set up registers for signal handler */
 448        regs->di = sig;
 449        /* In case the signal handler was declared without prototypes */
 450        regs->ax = 0;
 451
 452        /* This also works for non SA_SIGINFO handlers because they expect the
 453           next argument after the signal number on the stack. */
 454        regs->si = (unsigned long)&frame->info;
 455        regs->dx = (unsigned long)&frame->uc;
 456        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 457
 458        regs->sp = (unsigned long)frame;
 459
 460        /* Set up the CS register to run signal handlers in 64-bit mode,
 461           even if the handler happens to be interrupting 32-bit code. */
 462        regs->cs = __USER_CS;
 463
 464        return 0;
 465}
 466#endif /* CONFIG_X86_32 */
 467
 468static int x32_setup_rt_frame(struct ksignal *ksig,
 469                              compat_sigset_t *set,
 470                              struct pt_regs *regs)
 471{
 472#ifdef CONFIG_X86_X32_ABI
 473        struct rt_sigframe_x32 __user *frame;
 474        void __user *restorer;
 475        int err = 0;
 476        void __user *fpstate = NULL;
 477
 478        frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
 479
 480        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 481                return -EFAULT;
 482
 483        if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 484                if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 485                        return -EFAULT;
 486        }
 487
 488        put_user_try {
 489                /* Create the ucontext.  */
 490                if (cpu_has_xsave)
 491                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 492                else
 493                        put_user_ex(0, &frame->uc.uc_flags);
 494                put_user_ex(0, &frame->uc.uc_link);
 495                compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 496                put_user_ex(0, &frame->uc.uc__pad0);
 497
 498                if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 499                        restorer = ksig->ka.sa.sa_restorer;
 500                } else {
 501                        /* could use a vstub here */
 502                        restorer = NULL;
 503                        err |= -EFAULT;
 504                }
 505                put_user_ex(restorer, &frame->pretcode);
 506        } put_user_catch(err);
 507
 508        err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 509                                regs, set->sig[0]);
 510        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 511
 512        if (err)
 513                return -EFAULT;
 514
 515        /* Set up registers for signal handler */
 516        regs->sp = (unsigned long) frame;
 517        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 518
 519        /* We use the x32 calling convention here... */
 520        regs->di = ksig->sig;
 521        regs->si = (unsigned long) &frame->info;
 522        regs->dx = (unsigned long) &frame->uc;
 523
 524        loadsegment(ds, __USER_DS);
 525        loadsegment(es, __USER_DS);
 526
 527        regs->cs = __USER_CS;
 528        regs->ss = __USER_DS;
 529#endif  /* CONFIG_X86_X32_ABI */
 530
 531        return 0;
 532}
 533
 534/*
 535 * Do a signal return; undo the signal stack.
 536 */
 537#ifdef CONFIG_X86_32
 538asmlinkage unsigned long sys_sigreturn(void)
 539{
 540        struct pt_regs *regs = current_pt_regs();
 541        struct sigframe __user *frame;
 542        sigset_t set;
 543
 544        frame = (struct sigframe __user *)(regs->sp - 8);
 545
 546        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 547                goto badframe;
 548        if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 549                && __copy_from_user(&set.sig[1], &frame->extramask,
 550                                    sizeof(frame->extramask))))
 551                goto badframe;
 552
 553        set_current_blocked(&set);
 554
 555        if (restore_sigcontext(regs, &frame->sc))
 556                goto badframe;
 557        return regs->ax;
 558
 559badframe:
 560        signal_fault(regs, frame, "sigreturn");
 561
 562        return 0;
 563}
 564#endif /* CONFIG_X86_32 */
 565
 566asmlinkage long sys_rt_sigreturn(void)
 567{
 568        struct pt_regs *regs = current_pt_regs();
 569        struct rt_sigframe __user *frame;
 570        sigset_t set;
 571
 572        frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 573        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 574                goto badframe;
 575        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 576                goto badframe;
 577
 578        set_current_blocked(&set);
 579
 580        if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 581                goto badframe;
 582
 583        if (restore_altstack(&frame->uc.uc_stack))
 584                goto badframe;
 585
 586        return regs->ax;
 587
 588badframe:
 589        signal_fault(regs, frame, "rt_sigreturn");
 590        return 0;
 591}
 592
 593static inline int is_ia32_compat_frame(void)
 594{
 595        return config_enabled(CONFIG_IA32_EMULATION) &&
 596               test_thread_flag(TIF_IA32);
 597}
 598
 599static inline int is_ia32_frame(void)
 600{
 601        return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame();
 602}
 603
 604static inline int is_x32_frame(void)
 605{
 606        return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32);
 607}
 608
 609static int
 610setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 611{
 612        int usig = ksig->sig;
 613        sigset_t *set = sigmask_to_save();
 614        compat_sigset_t *cset = (compat_sigset_t *) set;
 615
 616        /* Set up the stack frame */
 617        if (is_ia32_frame()) {
 618                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 619                        return ia32_setup_rt_frame(usig, ksig, cset, regs);
 620                else
 621                        return ia32_setup_frame(usig, ksig, cset, regs);
 622        } else if (is_x32_frame()) {
 623                return x32_setup_rt_frame(ksig, cset, regs);
 624        } else {
 625                return __setup_rt_frame(ksig->sig, ksig, set, regs);
 626        }
 627}
 628
 629static void
 630handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 631{
 632        bool stepping, failed;
 633        struct fpu *fpu = &current->thread.fpu;
 634
 635        if (v8086_mode(regs))
 636                save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
 637
 638        /* Are we from a system call? */
 639        if (syscall_get_nr(current, regs) >= 0) {
 640                /* If so, check system call restarting.. */
 641                switch (syscall_get_error(current, regs)) {
 642                case -ERESTART_RESTARTBLOCK:
 643                case -ERESTARTNOHAND:
 644                        regs->ax = -EINTR;
 645                        break;
 646
 647                case -ERESTARTSYS:
 648                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 649                                regs->ax = -EINTR;
 650                                break;
 651                        }
 652                /* fallthrough */
 653                case -ERESTARTNOINTR:
 654                        regs->ax = regs->orig_ax;
 655                        regs->ip -= 2;
 656                        break;
 657                }
 658        }
 659
 660        /*
 661         * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
 662         * so that register information in the sigcontext is correct and
 663         * then notify the tracer before entering the signal handler.
 664         */
 665        stepping = test_thread_flag(TIF_SINGLESTEP);
 666        if (stepping)
 667                user_disable_single_step(current);
 668
 669        failed = (setup_rt_frame(ksig, regs) < 0);
 670        if (!failed) {
 671                /*
 672                 * Clear the direction flag as per the ABI for function entry.
 673                 *
 674                 * Clear RF when entering the signal handler, because
 675                 * it might disable possible debug exception from the
 676                 * signal handler.
 677                 *
 678                 * Clear TF for the case when it wasn't set by debugger to
 679                 * avoid the recursive send_sigtrap() in SIGTRAP handler.
 680                 */
 681                regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
 682                /*
 683                 * Ensure the signal handler starts with the new fpu state.
 684                 */
 685                if (fpu->fpstate_active)
 686                        fpu__clear(fpu);
 687        }
 688        signal_setup_done(failed, ksig, stepping);
 689}
 690
 691#ifdef CONFIG_X86_32
 692#define NR_restart_syscall      __NR_restart_syscall
 693#else /* !CONFIG_X86_32 */
 694#define NR_restart_syscall      \
 695        test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 696#endif /* CONFIG_X86_32 */
 697
 698/*
 699 * Note that 'init' is a special process: it doesn't get signals it doesn't
 700 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 701 * mistake.
 702 */
 703void do_signal(struct pt_regs *regs)
 704{
 705        struct ksignal ksig;
 706
 707        if (get_signal(&ksig)) {
 708                /* Whee! Actually deliver the signal.  */
 709                handle_signal(&ksig, regs);
 710                return;
 711        }
 712
 713        /* Did we come from a system call? */
 714        if (syscall_get_nr(current, regs) >= 0) {
 715                /* Restart the system call - no handlers present */
 716                switch (syscall_get_error(current, regs)) {
 717                case -ERESTARTNOHAND:
 718                case -ERESTARTSYS:
 719                case -ERESTARTNOINTR:
 720                        regs->ax = regs->orig_ax;
 721                        regs->ip -= 2;
 722                        break;
 723
 724                case -ERESTART_RESTARTBLOCK:
 725                        regs->ax = NR_restart_syscall;
 726                        regs->ip -= 2;
 727                        break;
 728                }
 729        }
 730
 731        /*
 732         * If there's no signal to deliver, we just put the saved sigmask
 733         * back.
 734         */
 735        restore_saved_sigmask();
 736}
 737
 738void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 739{
 740        struct task_struct *me = current;
 741
 742        if (show_unhandled_signals && printk_ratelimit()) {
 743                printk("%s"
 744                       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 745                       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 746                       me->comm, me->pid, where, frame,
 747                       regs->ip, regs->sp, regs->orig_ax);
 748                print_vma_addr(" in ", regs->ip);
 749                pr_cont("\n");
 750        }
 751
 752        force_sig(SIGSEGV, me);
 753}
 754
 755#ifdef CONFIG_X86_X32_ABI
 756asmlinkage long sys32_x32_rt_sigreturn(void)
 757{
 758        struct pt_regs *regs = current_pt_regs();
 759        struct rt_sigframe_x32 __user *frame;
 760        sigset_t set;
 761
 762        frame = (struct rt_sigframe_x32 __user *)(regs->sp - 8);
 763
 764        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 765                goto badframe;
 766        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 767                goto badframe;
 768
 769        set_current_blocked(&set);
 770
 771        if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 772                goto badframe;
 773
 774        if (compat_restore_altstack(&frame->uc.uc_stack))
 775                goto badframe;
 776
 777        return regs->ax;
 778
 779badframe:
 780        signal_fault(regs, frame, "x32 rt_sigreturn");
 781        return 0;
 782}
 783#endif
 784