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 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/kernel.h>
  14 #include <linux/signal.h>
  15 #include <linux/errno.h>
  16 #include <linux/wait.h>
  17 #include <linux/ptrace.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
  24 #include <asm/processor.h>
  25 #include <asm/ucontext.h>
  26 #include <asm/i387.h>
  27 #include <asm/vdso.h>
  28
  29 #ifdef CONFIG_X86_64
  30 #include <asm/proto.h>
  31 #include <asm/ia32_unistd.h>
  32 #include <asm/mce.h>
  33 #endif /* CONFIG_X86_64 */
  34
  35 #include <asm/syscall.h>
  36 #include <asm/syscalls.h>
  37
  38 #include <asm/sigframe.h>
  39
  40 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  41
  42 #define __FIX_EFLAGS    (X86_EFLAGS_AC | X86_EFLAGS_OF | \
  43                          X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
  44                          X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
  45                          X86_EFLAGS_CF)
  46
  47 #ifdef CONFIG_X86_32
  48 # define FIX_EFLAGS     (__FIX_EFLAGS | X86_EFLAGS_RF)
  49 #else
  50 # define FIX_EFLAGS     __FIX_EFLAGS
  51 #endif
  52
  53 #define COPY(x)                 do {                    \
  54         get_user_ex(regs->x, &sc->x);                   \
  55 } while (0)
  56
  57 #define GET_SEG(seg)            ({                      \
  58         unsigned short tmp;                             \
  59         get_user_ex(tmp, &sc->seg);                     \
  60         tmp;                                            \
  61 })
  62
  63 #define COPY_SEG(seg)           do {                    \
  64         regs->seg = GET_SEG(seg);                       \
  65 } while (0)
  66
  67 #define COPY_SEG_CPL3(seg)      do {                    \
  68         regs->seg = GET_SEG(seg) | 3;                   \
  69 } while (0)
  70
  71 static int
  72 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
  73                    unsigned long *pax)
  74 {
  75         void __user *buf;
  76         unsigned int tmpflags;
  77         unsigned int err = 0;
  78
  79         /* Always make any pending restarted system calls return -EINTR */
  80         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  81
  82         get_user_try {
  83
  84 #ifdef CONFIG_X86_32
  85                 set_user_gs(regs, GET_SEG(gs));
  86                 COPY_SEG(fs);
  87                 COPY_SEG(es);
  88                 COPY_SEG(ds);
  89 #endif /* CONFIG_X86_32 */
  90
  91                 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  92                 COPY(dx); COPY(cx); COPY(ip);
  93
  94 #ifdef CONFIG_X86_64
  95                 COPY(r8);
  96                 COPY(r9);
  97                 COPY(r10);
  98                 COPY(r11);
  99                 COPY(r12);
 100                 COPY(r13);
 101                 COPY(r14);
 102                 COPY(r15);
 103 #endif /* CONFIG_X86_64 */
 104
 105 #ifdef CONFIG_X86_32
 106                 COPY_SEG_CPL3(cs);
 107                 COPY_SEG_CPL3(ss);
 108 #else /* !CONFIG_X86_32 */
 109                 /* Kernel saves and restores only the CS segment register on signals,
 110                  * which is the bare minimum needed to allow mixed 32/64-bit code.
 111                  * App's signal handler can save/restore other segments if needed. */
 112                 COPY_SEG_CPL3(cs);
 113 #endif /* CONFIG_X86_32 */
 114
 115                 get_user_ex(tmpflags, &sc->flags);
 116                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 117                 regs->orig_ax = -1;             /* disable syscall checks */
 118
 119                 get_user_ex(buf, &sc->fpstate);
 120                 err |= restore_i387_xstate(buf);
 121
 122                 get_user_ex(*pax, &sc->ax);
 123         } get_user_catch(err);
 124
 125         return err;
 126 }
 127
 128 static int
 129 setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 130                  struct pt_regs *regs, unsigned long mask)
 131 {
 132         int err = 0;
 133
 134         put_user_try {
 135
 136 #ifdef CONFIG_X86_32
 137                 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
 138                 put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
 139                 put_user_ex(regs->es, (unsigned int __user *)&sc->es);
 140                 put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
 141 #endif /* CONFIG_X86_32 */
 142
 143                 put_user_ex(regs->di, &sc->di);
 144                 put_user_ex(regs->si, &sc->si);
 145                 put_user_ex(regs->bp, &sc->bp);
 146                 put_user_ex(regs->sp, &sc->sp);
 147                 put_user_ex(regs->bx, &sc->bx);
 148                 put_user_ex(regs->dx, &sc->dx);
 149                 put_user_ex(regs->cx, &sc->cx);
 150                 put_user_ex(regs->ax, &sc->ax);
 151 #ifdef CONFIG_X86_64
 152                 put_user_ex(regs->r8, &sc->r8);
 153                 put_user_ex(regs->r9, &sc->r9);
 154                 put_user_ex(regs->r10, &sc->r10);
 155                 put_user_ex(regs->r11, &sc->r11);
 156                 put_user_ex(regs->r12, &sc->r12);
 157                 put_user_ex(regs->r13, &sc->r13);
 158                 put_user_ex(regs->r14, &sc->r14);
 159                 put_user_ex(regs->r15, &sc->r15);
 160 #endif /* CONFIG_X86_64 */
 161
 162                 put_user_ex(current->thread.trap_no, &sc->trapno);
 163                 put_user_ex(current->thread.error_code, &sc->err);
 164                 put_user_ex(regs->ip, &sc->ip);
 165 #ifdef CONFIG_X86_32
 166                 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 167                 put_user_ex(regs->flags, &sc->flags);
 168                 put_user_ex(regs->sp, &sc->sp_at_signal);
 169                 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 170 #else /* !CONFIG_X86_32 */
 171                 put_user_ex(regs->flags, &sc->flags);
 172                 put_user_ex(regs->cs, &sc->cs);
 173                 put_user_ex(0, &sc->gs);
 174                 put_user_ex(0, &sc->fs);
 175 #endif /* CONFIG_X86_32 */
 176
 177                 put_user_ex(fpstate, &sc->fpstate);
 178
 179                 /* non-iBCS2 extensions.. */
 180                 put_user_ex(mask, &sc->oldmask);
 181                 put_user_ex(current->thread.cr2, &sc->cr2);
 182         } put_user_catch(err);
 183
 184         return err;
 185 }
 186
 187 /*
 188  * Set up a signal frame.
 189  */
 190 #ifdef CONFIG_X86_32
 191 static const struct {
 192         u16 poplmovl;
 193         u32 val;
 194         u16 int80;
 195 } __attribute__((packed)) retcode = {
 196         0xb858,         /* popl %eax; movl $..., %eax */
 197         __NR_sigreturn,
 198         0x80cd,         /* int $0x80 */
 199 };
 200
 201 static const struct {
 202         u8  movl;
 203         u32 val;
 204         u16 int80;
 205         u8  pad;
 206 } __attribute__((packed)) rt_retcode = {
 207         0xb8,           /* movl $..., %eax */
 208         __NR_rt_sigreturn,
 209         0x80cd,         /* int $0x80 */
 210         0
 211 };
 212
 213 /*
 214  * Determine which stack to use..
 215  */
 216 static inline void __user *
 217 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 218              void **fpstate)
 219 {
 220         unsigned long sp;
 221
 222         /* Default to using normal stack */
 223         sp = regs->sp;
 224
 225         /*
 226          * If we are on the alternate signal stack and would overflow it, don't.
 227          * Return an always-bogus address instead so we will die with SIGSEGV.
 228          */
 229         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 230                 return (void __user *) -1L;
 231
 232         /* This is the X/Open sanctioned signal stack switching.  */
 233         if (ka->sa.sa_flags & SA_ONSTACK) {
 234                 if (sas_ss_flags(sp) == 0)
 235                         sp = current->sas_ss_sp + current->sas_ss_size;
 236         } else {
 237                 /* This is the legacy signal stack switching. */
 238                 if ((regs->ss & 0xffff) != __USER_DS &&
 239                         !(ka->sa.sa_flags & SA_RESTORER) &&
 240                                 ka->sa.sa_restorer)
 241                         sp = (unsigned long) ka->sa.sa_restorer;
 242         }
 243
 244         if (used_math()) {
 245                 sp = sp - sig_xstate_size;
 246                 *fpstate = (struct _fpstate *) sp;
 247                 if (save_i387_xstate(*fpstate) < 0)
 248                         return (void __user *)-1L;
 249         }
 250
 251         sp -= frame_size;
 252         /*
 253          * Align the stack pointer according to the i386 ABI,
 254          * i.e. so that on function entry ((sp + 4) & 15) == 0.
 255          */
 256         sp = ((sp + 4) & -16ul) - 4;
 257
 258         return (void __user *) sp;
 259 }
 260
 261 static int
 262 __setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
 263               struct pt_regs *regs)
 264 {
 265         struct sigframe __user *frame;
 266         void __user *restorer;
 267         int err = 0;
 268         void __user *fpstate = NULL;
 269
 270         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 271
 272         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 273                 return -EFAULT;
 274
 275         if (__put_user(sig, &frame->sig))
 276                 return -EFAULT;
 277
 278         if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 279                 return -EFAULT;
 280
 281         if (_NSIG_WORDS > 1) {
 282                 if (__copy_to_user(&frame->extramask, &set->sig[1],
 283                                    sizeof(frame->extramask)))
 284                         return -EFAULT;
 285         }
 286
 287         if (current->mm->context.vdso)
 288                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
 289         else
 290                 restorer = &frame->retcode;
 291         if (ka->sa.sa_flags & SA_RESTORER)
 292                 restorer = ka->sa.sa_restorer;
 293
 294         /* Set up to return from userspace.  */
 295         err |= __put_user(restorer, &frame->pretcode);
 296
 297         /*
 298          * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
 299          *
 300          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 301          * reasons and because gdb uses it as a signature to notice
 302          * signal handler stack frames.
 303          */
 304         err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
 305
 306         if (err)
 307                 return -EFAULT;
 308
 309         /* Set up registers for signal handler */
 310         regs->sp = (unsigned long)frame;
 311         regs->ip = (unsigned long)ka->sa.sa_handler;
 312         regs->ax = (unsigned long)sig;
 313         regs->dx = 0;
 314         regs->cx = 0;
 315
 316         regs->ds = __USER_DS;
 317         regs->es = __USER_DS;
 318         regs->ss = __USER_DS;
 319         regs->cs = __USER_CS;
 320
 321         return 0;
 322 }
 323
 324 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 325                             sigset_t *set, struct pt_regs *regs)
 326 {
 327         struct rt_sigframe __user *frame;
 328         void __user *restorer;
 329         int err = 0;
 330         void __user *fpstate = NULL;
 331
 332         frame = get_sigframe(ka, regs, sizeof(*frame), &fpstate);
 333
 334         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 335                 return -EFAULT;
 336
 337         put_user_try {
 338                 put_user_ex(sig, &frame->sig);
 339                 put_user_ex(&frame->info, &frame->pinfo);
 340                 put_user_ex(&frame->uc, &frame->puc);
 341                 err |= copy_siginfo_to_user(&frame->info, info);
 342
 343                 /* Create the ucontext.  */
 344                 if (cpu_has_xsave)
 345                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 346                 else
 347                         put_user_ex(0, &frame->uc.uc_flags);
 348                 put_user_ex(0, &frame->uc.uc_link);
 349                 put_user_ex(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 350                 put_user_ex(sas_ss_flags(regs->sp),
 351                             &frame->uc.uc_stack.ss_flags);
 352                 put_user_ex(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 353                 err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 354                                         regs, set->sig[0]);
 355                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 356
 357                 /* Set up to return from userspace.  */
 358                 restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
 359                 if (ka->sa.sa_flags & SA_RESTORER)
 360                         restorer = ka->sa.sa_restorer;
 361                 put_user_ex(restorer, &frame->pretcode);
 362
 363                 /*
 364                  * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
 365                  *
 366                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
 367                  * reasons and because gdb uses it as a signature to notice
 368                  * signal handler stack frames.
 369                  */
 370                 put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
 371         } put_user_catch(err);
 372
 373         if (err)
 374                 return -EFAULT;
 375
 376         /* Set up registers for signal handler */
 377         regs->sp = (unsigned long)frame;
 378         regs->ip = (unsigned long)ka->sa.sa_handler;
 379         regs->ax = (unsigned long)sig;
 380         regs->dx = (unsigned long)&frame->info;
 381         regs->cx = (unsigned long)&frame->uc;
 382
 383         regs->ds = __USER_DS;
 384         regs->es = __USER_DS;
 385         regs->ss = __USER_DS;
 386         regs->cs = __USER_CS;
 387
 388         return 0;
 389 }
 390 #else /* !CONFIG_X86_32 */
 391 /*
 392  * Determine which stack to use..
 393  */
 394 static void __user *
 395 get_stack(struct k_sigaction *ka, unsigned long sp, unsigned long size)
 396 {
 397         /* Default to using normal stack - redzone*/
 398         sp -= 128;
 399
 400         /* This is the X/Open sanctioned signal stack switching.  */
 401         if (ka->sa.sa_flags & SA_ONSTACK) {
 402                 if (sas_ss_flags(sp) == 0)
 403                         sp = current->sas_ss_sp + current->sas_ss_size;
 404         }
 405
 406         return (void __user *)round_down(sp - size, 64);
 407 }
 408
 409 static int __setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 410                             sigset_t *set, struct pt_regs *regs)
 411 {
 412         struct rt_sigframe __user *frame;
 413         void __user *fp = NULL;
 414         int err = 0;
 415         struct task_struct *me = current;
 416
 417         if (used_math()) {
 418                 fp = get_stack(ka, regs->sp, sig_xstate_size);
 419                 frame = (void __user *)round_down(
 420                         (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
 421
 422                 if (save_i387_xstate(fp) < 0)
 423                         return -EFAULT;
 424         } else
 425                 frame = get_stack(ka, regs->sp, sizeof(struct rt_sigframe)) - 8;
 426
 427         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 428                 return -EFAULT;
 429
 430         if (ka->sa.sa_flags & SA_SIGINFO) {
 431                 if (copy_siginfo_to_user(&frame->info, info))
 432                         return -EFAULT;
 433         }
 434
 435         put_user_try {
 436                 /* Create the ucontext.  */
 437                 if (cpu_has_xsave)
 438                         put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 439                 else
 440                         put_user_ex(0, &frame->uc.uc_flags);
 441                 put_user_ex(0, &frame->uc.uc_link);
 442                 put_user_ex(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 443                 put_user_ex(sas_ss_flags(regs->sp),
 444                             &frame->uc.uc_stack.ss_flags);
 445                 put_user_ex(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
 446                 err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
 447                 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 448
 449                 /* Set up to return from userspace.  If provided, use a stub
 450                    already in userspace.  */
 451                 /* x86-64 should always use SA_RESTORER. */
 452                 if (ka->sa.sa_flags & SA_RESTORER) {
 453                         put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
 454                 } else {
 455                         /* could use a vstub here */
 456                         err |= -EFAULT;
 457                 }
 458         } put_user_catch(err);
 459
 460         if (err)
 461                 return -EFAULT;
 462
 463         /* Set up registers for signal handler */
 464         regs->di = sig;
 465         /* In case the signal handler was declared without prototypes */
 466         regs->ax = 0;
 467
 468         /* This also works for non SA_SIGINFO handlers because they expect the
 469            next argument after the signal number on the stack. */
 470         regs->si = (unsigned long)&frame->info;
 471         regs->dx = (unsigned long)&frame->uc;
 472         regs->ip = (unsigned long) ka->sa.sa_handler;
 473
 474         regs->sp = (unsigned long)frame;
 475
 476         /* Set up the CS register to run signal handlers in 64-bit mode,
 477            even if the handler happens to be interrupting 32-bit code. */
 478         regs->cs = __USER_CS;
 479
 480         return 0;
 481 }
 482 #endif /* CONFIG_X86_32 */
 483
 484 #ifdef CONFIG_X86_32
 485 /*
 486  * Atomically swap in the new signal mask, and wait for a signal.
 487  */
 488 asmlinkage int
 489 sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 490 {
 491         mask &= _BLOCKABLE;
 492         spin_lock_irq(&current->sighand->siglock);
 493         current->saved_sigmask = current->blocked;
 494         siginitset(&current->blocked, mask);
 495         recalc_sigpending();
 496         spin_unlock_irq(&current->sighand->siglock);
 497
 498         current->state = TASK_INTERRUPTIBLE;
 499         schedule();
 500         set_restore_sigmask();
 501
 502         return -ERESTARTNOHAND;
 503 }
 504
 505 asmlinkage int
 506 sys_sigaction(int sig, const struct old_sigaction __user *act,
 507               struct old_sigaction __user *oact)
 508 {
 509         struct k_sigaction new_ka, old_ka;
 510         int ret = 0;
 511
 512         if (act) {
 513                 old_sigset_t mask;
 514
 515                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 516                         return -EFAULT;
 517
 518                 get_user_try {
 519                         get_user_ex(new_ka.sa.sa_handler, &act->sa_handler);
 520                         get_user_ex(new_ka.sa.sa_flags, &act->sa_flags);
 521                         get_user_ex(mask, &act->sa_mask);
 522                         get_user_ex(new_ka.sa.sa_restorer, &act->sa_restorer);
 523                 } get_user_catch(ret);
 524
 525                 if (ret)
 526                         return -EFAULT;
 527                 siginitset(&new_ka.sa.sa_mask, mask);
 528         }
 529
 530         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 531
 532         if (!ret && oact) {
 533                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 534                         return -EFAULT;
 535
 536                 put_user_try {
 537                         put_user_ex(old_ka.sa.sa_handler, &oact->sa_handler);
 538                         put_user_ex(old_ka.sa.sa_flags, &oact->sa_flags);
 539                         put_user_ex(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 540                         put_user_ex(old_ka.sa.sa_restorer, &oact->sa_restorer);
 541                 } put_user_catch(ret);
 542
 543                 if (ret)
 544                         return -EFAULT;
 545         }
 546
 547         return ret;
 548 }
 549 #endif /* CONFIG_X86_32 */
 550
 551 #ifdef CONFIG_X86_32
 552 asmlinkage int sys_sigaltstack(unsigned long bx)
 553 {
 554         /*
 555          * This is needed to make gcc realize it doesn't own the
 556          * "struct pt_regs"
 557          */
 558         struct pt_regs *regs = (struct pt_regs *)&bx;
 559         const stack_t __user *uss = (const stack_t __user *)bx;
 560         stack_t __user *uoss = (stack_t __user *)regs->cx;
 561
 562         return do_sigaltstack(uss, uoss, regs->sp);
 563 }
 564 #else /* !CONFIG_X86_32 */
 565 asmlinkage long
 566 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 567                 struct pt_regs *regs)
 568 {
 569         return do_sigaltstack(uss, uoss, regs->sp);
 570 }
 571 #endif /* CONFIG_X86_32 */
 572
 573 /*
 574  * Do a signal return; undo the signal stack.
 575  */
 576 #ifdef CONFIG_X86_32
 577 asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
 578 {
 579         struct sigframe __user *frame;
 580         struct pt_regs *regs;
 581         unsigned long ax;
 582         sigset_t set;
 583
 584         regs = (struct pt_regs *) &__unused;
 585         frame = (struct sigframe __user *)(regs->sp - 8);
 586
 587         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 588                 goto badframe;
 589         if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1
 590                 && __copy_from_user(&set.sig[1], &frame->extramask,
 591                                     sizeof(frame->extramask))))
 592                 goto badframe;
 593
 594         sigdelsetmask(&set, ~_BLOCKABLE);
 595         spin_lock_irq(&current->sighand->siglock);
 596         current->blocked = set;
 597         recalc_sigpending();
 598         spin_unlock_irq(&current->sighand->siglock);
 599
 600         if (restore_sigcontext(regs, &frame->sc, &ax))
 601                 goto badframe;
 602         return ax;
 603
 604 badframe:
 605         signal_fault(regs, frame, "sigreturn");
 606
 607         return 0;
 608 }
 609 #endif /* CONFIG_X86_32 */
 610
 611 static long do_rt_sigreturn(struct pt_regs *regs)
 612 {
 613         struct rt_sigframe __user *frame;
 614         unsigned long ax;
 615         sigset_t set;
 616
 617         frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 618         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 619                 goto badframe;
 620         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 621                 goto badframe;
 622
 623         sigdelsetmask(&set, ~_BLOCKABLE);
 624         spin_lock_irq(&current->sighand->siglock);
 625         current->blocked = set;
 626         recalc_sigpending();
 627         spin_unlock_irq(&current->sighand->siglock);
 628
 629         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
 630                 goto badframe;
 631
 632         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
 633                 goto badframe;
 634
 635         return ax;
 636
 637 badframe:
 638         signal_fault(regs, frame, "rt_sigreturn");
 639         return 0;
 640 }
 641
 642 #ifdef CONFIG_X86_32
 643 /*
 644  * Note: do not pass in pt_regs directly as with tail-call optimization
 645  * GCC will incorrectly stomp on the caller's frame and corrupt user-space
 646  * register state:
 647  */
 648 asmlinkage int sys_rt_sigreturn(unsigned long __unused)
 649 {
 650         struct pt_regs *regs = (struct pt_regs *)&__unused;
 651
 652         return do_rt_sigreturn(regs);
 653 }
 654 #else /* !CONFIG_X86_32 */
 655 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 656 {
 657         return do_rt_sigreturn(regs);
 658 }
 659 #endif /* CONFIG_X86_32 */
 660
 661 /*
 662  * OK, we're invoking a handler:
 663  */
 664 static int signr_convert(int sig)
 665 {
 666 #ifdef CONFIG_X86_32
 667         struct thread_info *info = current_thread_info();
 668
 669         if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32)
 670                 return info->exec_domain->signal_invmap[sig];
 671 #endif /* CONFIG_X86_32 */
 672         return sig;
 673 }
 674
 675 #ifdef CONFIG_X86_32
 676
 677 #define is_ia32 1
 678 #define ia32_setup_frame        __setup_frame
 679 #define ia32_setup_rt_frame     __setup_rt_frame
 680
 681 #else /* !CONFIG_X86_32 */
 682
 683 #ifdef CONFIG_IA32_EMULATION
 684 #define is_ia32 test_thread_flag(TIF_IA32)
 685 #else /* !CONFIG_IA32_EMULATION */
 686 #define is_ia32 0
 687 #endif /* CONFIG_IA32_EMULATION */
 688
 689 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 690                 sigset_t *set, struct pt_regs *regs);
 691 int ia32_setup_frame(int sig, struct k_sigaction *ka,
 692                 sigset_t *set, struct pt_regs *regs);
 693
 694 #endif /* CONFIG_X86_32 */
 695
 696 static int
 697 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 698                sigset_t *set, struct pt_regs *regs)
 699 {
 700         int usig = signr_convert(sig);
 701         int ret;
 702
 703         /* Set up the stack frame */
 704         if (is_ia32) {
 705                 if (ka->sa.sa_flags & SA_SIGINFO)
 706                         ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
 707                 else
 708                         ret = ia32_setup_frame(usig, ka, set, regs);
 709         } else
 710                 ret = __setup_rt_frame(sig, ka, info, set, regs);
 711
 712         if (ret) {
 713                 force_sigsegv(sig, current);
 714                 return -EFAULT;
 715         }
 716
 717         return ret;
 718 }
 719
 720 static int
 721 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 722               sigset_t *oldset, struct pt_regs *regs)
 723 {
 724         int ret;
 725
 726         /* Are we from a system call? */
 727         if (syscall_get_nr(current, regs) >= 0) {
 728                 /* If so, check system call restarting.. */
 729                 switch (syscall_get_error(current, regs)) {
 730                 case -ERESTART_RESTARTBLOCK:
 731                 case -ERESTARTNOHAND:
 732                         regs->ax = -EINTR;
 733                         break;
 734
 735                 case -ERESTARTSYS:
 736                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 737                                 regs->ax = -EINTR;
 738                                 break;
 739                         }
 740                 /* fallthrough */
 741                 case -ERESTARTNOINTR:
 742                         regs->ax = regs->orig_ax;
 743                         regs->ip -= 2;
 744                         break;
 745                 }
 746         }
 747
 748         /*
 749          * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
 750          * flag so that register information in the sigcontext is correct.
 751          */
 752         if (unlikely(regs->flags & X86_EFLAGS_TF) &&
 753             likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 754                 regs->flags &= ~X86_EFLAGS_TF;
 755
 756         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 757
 758         if (ret)
 759                 return ret;
 760
 761 #ifdef CONFIG_X86_64
 762         /*
 763          * This has nothing to do with segment registers,
 764          * despite the name.  This magic affects uaccess.h
 765          * macros' behavior.  Reset it to the normal setting.
 766          */
 767         set_fs(USER_DS);
 768 #endif
 769
 770         /*
 771          * Clear the direction flag as per the ABI for function entry.
 772          */
 773         regs->flags &= ~X86_EFLAGS_DF;
 774
 775         /*
 776          * Clear TF when entering the signal handler, but
 777          * notify any tracer that was single-stepping it.
 778          * The tracer may want to single-step inside the
 779          * handler too.
 780          */
 781         regs->flags &= ~X86_EFLAGS_TF;
 782
 783         spin_lock_irq(&current->sighand->siglock);
 784         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 785         if (!(ka->sa.sa_flags & SA_NODEFER))
 786                 sigaddset(&current->blocked, sig);
 787         recalc_sigpending();
 788         spin_unlock_irq(&current->sighand->siglock);
 789
 790         tracehook_signal_handler(sig, info, ka, regs,
 791                                  test_thread_flag(TIF_SINGLESTEP));
 792
 793         return 0;
 794 }
 795
 796 #ifdef CONFIG_X86_32
 797 #define NR_restart_syscall      __NR_restart_syscall
 798 #else /* !CONFIG_X86_32 */
 799 #define NR_restart_syscall      \
 800         test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall
 801 #endif /* CONFIG_X86_32 */
 802
 803 /*
 804  * Note that 'init' is a special process: it doesn't get signals it doesn't
 805  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 806  * mistake.
 807  */
 808 static void do_signal(struct pt_regs *regs)
 809 {
 810         struct k_sigaction ka;
 811         siginfo_t info;
 812         int signr;
 813         sigset_t *oldset;
 814
 815         /*
 816          * We want the common case to go fast, which is why we may in certain
 817          * cases get here from kernel mode. Just return without doing anything
 818          * if so.
 819          * X86_32: vm86 regs switched out by assembly code before reaching
 820          * here, so testing against kernel CS suffices.
 821          */
 822         if (!user_mode(regs))
 823                 return;
 824
 825         if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 826                 oldset = &current->saved_sigmask;
 827         else
 828                 oldset = &current->blocked;
 829
 830         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 831         if (signr > 0) {
 832                 /*
 833                  * Re-enable any watchpoints before delivering the
 834                  * signal to user space. The processor register will
 835                  * have been cleared if the watchpoint triggered
 836                  * inside the kernel.
 837                  */
 838                 if (current->thread.debugreg7)
 839                         set_debugreg(current->thread.debugreg7, 7);
 840
 841                 /* Whee! Actually deliver the signal.  */
 842                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 843                         /*
 844                          * A signal was successfully delivered; the saved
 845                          * sigmask will have been stored in the signal frame,
 846                          * and will be restored by sigreturn, so we can simply
 847                          * clear the TS_RESTORE_SIGMASK flag.
 848                          */
 849                         current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 850                 }
 851                 return;
 852         }
 853
 854         /* Did we come from a system call? */
 855         if (syscall_get_nr(current, regs) >= 0) {
 856                 /* Restart the system call - no handlers present */
 857                 switch (syscall_get_error(current, regs)) {
 858                 case -ERESTARTNOHAND:
 859                 case -ERESTARTSYS:
 860                 case -ERESTARTNOINTR:
 861                         regs->ax = regs->orig_ax;
 862                         regs->ip -= 2;
 863                         break;
 864
 865                 case -ERESTART_RESTARTBLOCK:
 866                         regs->ax = NR_restart_syscall;
 867                         regs->ip -= 2;
 868                         break;
 869                 }
 870         }
 871
 872         /*
 873          * If there's no signal to deliver, we just put the saved sigmask
 874          * back.
 875          */
 876         if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 877                 current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 878                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 879         }
 880 }
 881
 882 /*
 883  * notification of userspace execution resumption
 884  * - triggered by the TIF_WORK_MASK flags
 885  */
 886 void
 887 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 888 {
 889 #if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
 890         /* notify userspace of pending MCEs */
 891         if (thread_info_flags & _TIF_MCE_NOTIFY)
 892                 mce_notify_user();
 893 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 894
 895         /* deal with pending signal delivery */
 896         if (thread_info_flags & _TIF_SIGPENDING)
 897                 do_signal(regs);
 898
 899         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 900                 clear_thread_flag(TIF_NOTIFY_RESUME);
 901                 tracehook_notify_resume(regs);
 902         }
 903
 904 #ifdef CONFIG_X86_32
 905         clear_thread_flag(TIF_IRET);
 906 #endif /* CONFIG_X86_32 */
 907 }
 908
 909 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
 910 {
 911         struct task_struct *me = current;
 912
 913         if (show_unhandled_signals && printk_ratelimit()) {
 914                 printk("%s"
 915                        "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
 916                        task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
 917                        me->comm, me->pid, where, frame,
 918                        regs->ip, regs->sp, regs->orig_ax);
 919                 print_vma_addr(" in ", regs->ip);
 920                 printk(KERN_CONT "\n");
 921         }
 922
 923         force_sig(SIGSEGV, me);
 924 }