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   1 /*  linux/arch/sparc/kernel/signal.c
   2  *
   3  *  Copyright (C) 1991, 1992  Linus Torvalds
   4  *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
   6  *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
   7  */
   8
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/signal.h>
  12 #include <linux/errno.h>
  13 #include <linux/wait.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/unistd.h>
  16 #include <linux/mm.h>
  17 #include <linux/tty.h>
  18 #include <linux/smp.h>
  19 #include <linux/binfmts.h>      /* do_coredum */
  20 #include <linux/bitops.h>
  21 #include <linux/tracehook.h>
  22
  23 #include <asm/uaccess.h>
  24 #include <asm/ptrace.h>
  25 #include <asm/pgalloc.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/cacheflush.h>     /* flush_sig_insns */
  28
  29 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  30
  31 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
  32                    void *fpqueue, unsigned long *fpqdepth);
  33 extern void fpload(unsigned long *fpregs, unsigned long *fsr);
  34
  35 struct signal_frame {
  36         struct sparc_stackf     ss;
  37         __siginfo_t             info;
  38         __siginfo_fpu_t __user  *fpu_save;
  39         unsigned long           insns[2] __attribute__ ((aligned (8)));
  40         unsigned int            extramask[_NSIG_WORDS - 1];
  41         unsigned int            extra_size; /* Should be 0 */
  42         __siginfo_fpu_t         fpu_state;
  43 };
  44
  45 struct rt_signal_frame {
  46         struct sparc_stackf     ss;
  47         siginfo_t               info;
  48         struct pt_regs          regs;
  49         sigset_t                mask;
  50         __siginfo_fpu_t __user  *fpu_save;
  51         unsigned int            insns[2];
  52         stack_t                 stack;
  53         unsigned int            extra_size; /* Should be 0 */
  54         __siginfo_fpu_t         fpu_state;
  55 };
  56
  57 /* Align macros */
  58 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
  59 #define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))
  60
  61 static int _sigpause_common(old_sigset_t set)
  62 {
  63         set &= _BLOCKABLE;
  64         spin_lock_irq(&current->sighand->siglock);
  65         current->saved_sigmask = current->blocked;
  66         siginitset(&current->blocked, set);
  67         recalc_sigpending();
  68         spin_unlock_irq(&current->sighand->siglock);
  69
  70         current->state = TASK_INTERRUPTIBLE;
  71         schedule();
  72         set_thread_flag(TIF_RESTORE_SIGMASK);
  73
  74         return -ERESTARTNOHAND;
  75 }
  76
  77 asmlinkage int sys_sigsuspend(old_sigset_t set)
  78 {
  79         return _sigpause_common(set);
  80 }
  81
  82 static inline int
  83 restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
  84 {
  85         int err;
  86 #ifdef CONFIG_SMP
  87         if (test_tsk_thread_flag(current, TIF_USEDFPU))
  88                 regs->psr &= ~PSR_EF;
  89 #else
  90         if (current == last_task_used_math) {
  91                 last_task_used_math = NULL;
  92                 regs->psr &= ~PSR_EF;
  93         }
  94 #endif
  95         set_used_math();
  96         clear_tsk_thread_flag(current, TIF_USEDFPU);
  97
  98         if (!access_ok(VERIFY_READ, fpu, sizeof(*fpu)))
  99                 return -EFAULT;
 100
 101         err = __copy_from_user(&current->thread.float_regs[0], &fpu->si_float_regs[0],
 102                                (sizeof(unsigned long) * 32));
 103         err |= __get_user(current->thread.fsr, &fpu->si_fsr);
 104         err |= __get_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
 105         if (current->thread.fpqdepth != 0)
 106                 err |= __copy_from_user(&current->thread.fpqueue[0],
 107                                         &fpu->si_fpqueue[0],
 108                                         ((sizeof(unsigned long) +
 109                                         (sizeof(unsigned long *)))*16));
 110         return err;
 111 }
 112
 113 asmlinkage void do_sigreturn(struct pt_regs *regs)
 114 {
 115         struct signal_frame __user *sf;
 116         unsigned long up_psr, pc, npc;
 117         sigset_t set;
 118         __siginfo_fpu_t __user *fpu_save;
 119         int err;
 120
 121         /* Always make any pending restarted system calls return -EINTR */
 122         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 123
 124         synchronize_user_stack();
 125
 126         sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
 127
 128         /* 1. Make sure we are not getting garbage from the user */
 129         if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
 130                 goto segv_and_exit;
 131
 132         if (((unsigned long) sf) & 3)
 133                 goto segv_and_exit;
 134
 135         err = __get_user(pc,  &sf->info.si_regs.pc);
 136         err |= __get_user(npc, &sf->info.si_regs.npc);
 137
 138         if ((pc | npc) & 3)
 139                 goto segv_and_exit;
 140
 141         /* 2. Restore the state */
 142         up_psr = regs->psr;
 143         err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
 144
 145         /* User can only change condition codes and FPU enabling in %psr. */
 146         regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
 147                   | (regs->psr & (PSR_ICC | PSR_EF));
 148
 149         /* Prevent syscall restart.  */
 150         pt_regs_clear_syscall(regs);
 151
 152         err |= __get_user(fpu_save, &sf->fpu_save);
 153
 154         if (fpu_save)
 155                 err |= restore_fpu_state(regs, fpu_save);
 156
 157         /* This is pretty much atomic, no amount locking would prevent
 158          * the races which exist anyways.
 159          */
 160         err |= __get_user(set.sig[0], &sf->info.si_mask);
 161         err |= __copy_from_user(&set.sig[1], &sf->extramask,
 162                                 (_NSIG_WORDS-1) * sizeof(unsigned int));
 163
 164         if (err)
 165                 goto segv_and_exit;
 166
 167         sigdelsetmask(&set, ~_BLOCKABLE);
 168         spin_lock_irq(&current->sighand->siglock);
 169         current->blocked = set;
 170         recalc_sigpending();
 171         spin_unlock_irq(&current->sighand->siglock);
 172         return;
 173
 174 segv_and_exit:
 175         force_sig(SIGSEGV, current);
 176 }
 177
 178 asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 179 {
 180         struct rt_signal_frame __user *sf;
 181         unsigned int psr, pc, npc;
 182         __siginfo_fpu_t __user *fpu_save;
 183         mm_segment_t old_fs;
 184         sigset_t set;
 185         stack_t st;
 186         int err;
 187
 188         synchronize_user_stack();
 189         sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
 190         if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
 191             (((unsigned long) sf) & 0x03))
 192                 goto segv;
 193
 194         err = __get_user(pc, &sf->regs.pc);
 195         err |= __get_user(npc, &sf->regs.npc);
 196         err |= ((pc | npc) & 0x03);
 197
 198         err |= __get_user(regs->y, &sf->regs.y);
 199         err |= __get_user(psr, &sf->regs.psr);
 200
 201         err |= __copy_from_user(&regs->u_regs[UREG_G1],
 202                                 &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
 203
 204         regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
 205
 206         /* Prevent syscall restart.  */
 207         pt_regs_clear_syscall(regs);
 208
 209         err |= __get_user(fpu_save, &sf->fpu_save);
 210
 211         if (fpu_save)
 212                 err |= restore_fpu_state(regs, fpu_save);
 213         err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 214
 215         err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
 216
 217         if (err)
 218                 goto segv;
 219
 220         regs->pc = pc;
 221         regs->npc = npc;
 222
 223         /* It is more difficult to avoid calling this function than to
 224          * call it and ignore errors.
 225          */
 226         old_fs = get_fs();
 227         set_fs(KERNEL_DS);
 228         do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
 229         set_fs(old_fs);
 230
 231         sigdelsetmask(&set, ~_BLOCKABLE);
 232         spin_lock_irq(&current->sighand->siglock);
 233         current->blocked = set;
 234         recalc_sigpending();
 235         spin_unlock_irq(&current->sighand->siglock);
 236         return;
 237 segv:
 238         force_sig(SIGSEGV, current);
 239 }
 240
 241 /* Checks if the fp is valid */
 242 static inline int invalid_frame_pointer(void __user *fp, int fplen)
 243 {
 244         if ((((unsigned long) fp) & 7) ||
 245             !__access_ok((unsigned long)fp, fplen) ||
 246             ((sparc_cpu_model == sun4 || sparc_cpu_model == sun4c) &&
 247              ((unsigned long) fp < 0xe0000000 && (unsigned long) fp >= 0x20000000)))
 248                 return 1;
 249
 250         return 0;
 251 }
 252
 253 static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
 254 {
 255         unsigned long sp = regs->u_regs[UREG_FP];
 256
 257         /*
 258          * If we are on the alternate signal stack and would overflow it, don't.
 259          * Return an always-bogus address instead so we will die with SIGSEGV.
 260          */
 261         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 262                 return (void __user *) -1L;
 263
 264         /* This is the X/Open sanctioned signal stack switching.  */
 265         if (sa->sa_flags & SA_ONSTACK) {
 266                 if (sas_ss_flags(sp) == 0)
 267                         sp = current->sas_ss_sp + current->sas_ss_size;
 268         }
 269
 270         /* Always align the stack frame.  This handles two cases.  First,
 271          * sigaltstack need not be mindful of platform specific stack
 272          * alignment.  Second, if we took this signal because the stack
 273          * is not aligned properly, we'd like to take the signal cleanly
 274          * and report that.
 275          */
 276         sp &= ~7UL;
 277
 278         return (void __user *)(sp - framesize);
 279 }
 280
 281 static inline int
 282 save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
 283 {
 284         int err = 0;
 285 #ifdef CONFIG_SMP
 286         if (test_tsk_thread_flag(current, TIF_USEDFPU)) {
 287                 put_psr(get_psr() | PSR_EF);
 288                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 289                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 290                 regs->psr &= ~(PSR_EF);
 291                 clear_tsk_thread_flag(current, TIF_USEDFPU);
 292         }
 293 #else
 294         if (current == last_task_used_math) {
 295                 put_psr(get_psr() | PSR_EF);
 296                 fpsave(&current->thread.float_regs[0], &current->thread.fsr,
 297                        &current->thread.fpqueue[0], &current->thread.fpqdepth);
 298                 last_task_used_math = NULL;
 299                 regs->psr &= ~(PSR_EF);
 300         }
 301 #endif
 302         err |= __copy_to_user(&fpu->si_float_regs[0],
 303                               &current->thread.float_regs[0],
 304                               (sizeof(unsigned long) * 32));
 305         err |= __put_user(current->thread.fsr, &fpu->si_fsr);
 306         err |= __put_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
 307         if (current->thread.fpqdepth != 0)
 308                 err |= __copy_to_user(&fpu->si_fpqueue[0],
 309                                       &current->thread.fpqueue[0],
 310                                       ((sizeof(unsigned long) +
 311                                       (sizeof(unsigned long *)))*16));
 312         clear_used_math();
 313         return err;
 314 }
 315
 316 static void setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
 317                         int signo, sigset_t *oldset)
 318 {
 319         struct signal_frame __user *sf;
 320         int sigframe_size, err;
 321
 322         /* 1. Make sure everything is clean */
 323         synchronize_user_stack();
 324
 325         sigframe_size = SF_ALIGNEDSZ;
 326         if (!used_math())
 327                 sigframe_size -= sizeof(__siginfo_fpu_t);
 328
 329         sf = (struct signal_frame __user *)
 330                 get_sigframe(&ka->sa, regs, sigframe_size);
 331
 332         if (invalid_frame_pointer(sf, sigframe_size))
 333                 goto sigill_and_return;
 334
 335         if (current_thread_info()->w_saved != 0)
 336                 goto sigill_and_return;
 337
 338         /* 2. Save the current process state */
 339         err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
 340
 341         err |= __put_user(0, &sf->extra_size);
 342
 343         if (used_math()) {
 344                 err |= save_fpu_state(regs, &sf->fpu_state);
 345                 err |= __put_user(&sf->fpu_state, &sf->fpu_save);
 346         } else {
 347                 err |= __put_user(0, &sf->fpu_save);
 348         }
 349
 350         err |= __put_user(oldset->sig[0], &sf->info.si_mask);
 351         err |= __copy_to_user(sf->extramask, &oldset->sig[1],
 352                               (_NSIG_WORDS - 1) * sizeof(unsigned int));
 353         err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 354                               sizeof(struct reg_window));
 355         if (err)
 356                 goto sigsegv;
 357
 358         /* 3. signal handler back-trampoline and parameters */
 359         regs->u_regs[UREG_FP] = (unsigned long) sf;
 360         regs->u_regs[UREG_I0] = signo;
 361         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 362         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
 363
 364         /* 4. signal handler */
 365         regs->pc = (unsigned long) ka->sa.sa_handler;
 366         regs->npc = (regs->pc + 4);
 367
 368         /* 5. return to kernel instructions */
 369         if (ka->ka_restorer)
 370                 regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
 371         else {
 372                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 373
 374                 /* mov __NR_sigreturn, %g1 */
 375                 err |= __put_user(0x821020d8, &sf->insns[0]);
 376
 377                 /* t 0x10 */
 378                 err |= __put_user(0x91d02010, &sf->insns[1]);
 379                 if (err)
 380                         goto sigsegv;
 381
 382                 /* Flush instruction space. */
 383                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 384         }
 385         return;
 386
 387 sigill_and_return:
 388         do_exit(SIGILL);
 389 sigsegv:
 390         force_sigsegv(signo, current);
 391 }
 392
 393 static void setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 394                            int signo, sigset_t *oldset, siginfo_t *info)
 395 {
 396         struct rt_signal_frame __user *sf;
 397         int sigframe_size;
 398         unsigned int psr;
 399         int err;
 400
 401         synchronize_user_stack();
 402         sigframe_size = RT_ALIGNEDSZ;
 403         if (!used_math())
 404                 sigframe_size -= sizeof(__siginfo_fpu_t);
 405         sf = (struct rt_signal_frame __user *)
 406                 get_sigframe(&ka->sa, regs, sigframe_size);
 407         if (invalid_frame_pointer(sf, sigframe_size))
 408                 goto sigill;
 409         if (current_thread_info()->w_saved != 0)
 410                 goto sigill;
 411
 412         err  = __put_user(regs->pc, &sf->regs.pc);
 413         err |= __put_user(regs->npc, &sf->regs.npc);
 414         err |= __put_user(regs->y, &sf->regs.y);
 415         psr = regs->psr;
 416         if (used_math())
 417                 psr |= PSR_EF;
 418         err |= __put_user(psr, &sf->regs.psr);
 419         err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
 420         err |= __put_user(0, &sf->extra_size);
 421
 422         if (psr & PSR_EF) {
 423                 err |= save_fpu_state(regs, &sf->fpu_state);
 424                 err |= __put_user(&sf->fpu_state, &sf->fpu_save);
 425         } else {
 426                 err |= __put_user(0, &sf->fpu_save);
 427         }
 428         err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
 429
 430         /* Setup sigaltstack */
 431         err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
 432         err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
 433         err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
 434
 435         err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
 436                               sizeof(struct reg_window));
 437
 438         err |= copy_siginfo_to_user(&sf->info, info);
 439
 440         if (err)
 441                 goto sigsegv;
 442
 443         regs->u_regs[UREG_FP] = (unsigned long) sf;
 444         regs->u_regs[UREG_I0] = signo;
 445         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 446         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
 447
 448         regs->pc = (unsigned long) ka->sa.sa_handler;
 449         regs->npc = (regs->pc + 4);
 450
 451         if (ka->ka_restorer)
 452                 regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
 453         else {
 454                 regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
 455
 456                 /* mov __NR_sigreturn, %g1 */
 457                 err |= __put_user(0x821020d8, &sf->insns[0]);
 458
 459                 /* t 0x10 */
 460                 err |= __put_user(0x91d02010, &sf->insns[1]);
 461                 if (err)
 462                         goto sigsegv;
 463
 464                 /* Flush instruction space. */
 465                 flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
 466         }
 467         return;
 468
 469 sigill:
 470         do_exit(SIGILL);
 471 sigsegv:
 472         force_sigsegv(signo, current);
 473 }
 474
 475 static inline void
 476 handle_signal(unsigned long signr, struct k_sigaction *ka,
 477               siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 478 {
 479         if (ka->sa.sa_flags & SA_SIGINFO)
 480                 setup_rt_frame(ka, regs, signr, oldset, info);
 481         else
 482                 setup_frame(ka, regs, signr, oldset);
 483
 484         spin_lock_irq(&current->sighand->siglock);
 485         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 486         if (!(ka->sa.sa_flags & SA_NOMASK))
 487                 sigaddset(&current->blocked, signr);
 488         recalc_sigpending();
 489         spin_unlock_irq(&current->sighand->siglock);
 490 }
 491
 492 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 493                                    struct sigaction *sa)
 494 {
 495         switch(regs->u_regs[UREG_I0]) {
 496         case ERESTART_RESTARTBLOCK:
 497         case ERESTARTNOHAND:
 498         no_system_call_restart:
 499                 regs->u_regs[UREG_I0] = EINTR;
 500                 regs->psr |= PSR_C;
 501                 break;
 502         case ERESTARTSYS:
 503                 if (!(sa->sa_flags & SA_RESTART))
 504                         goto no_system_call_restart;
 505                 /* fallthrough */
 506         case ERESTARTNOINTR:
 507                 regs->u_regs[UREG_I0] = orig_i0;
 508                 regs->pc -= 4;
 509                 regs->npc -= 4;
 510         }
 511 }
 512
 513 /* Note that 'init' is a special process: it doesn't get signals it doesn't
 514  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 515  * mistake.
 516  */
 517 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 518 {
 519         struct k_sigaction ka;
 520         int restart_syscall;
 521         sigset_t *oldset;
 522         siginfo_t info;
 523         int signr;
 524
 525         if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
 526                 restart_syscall = 1;
 527         else
 528                 restart_syscall = 0;
 529
 530         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 531                 oldset = &current->saved_sigmask;
 532         else
 533                 oldset = &current->blocked;
 534
 535         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 536
 537         /* If the debugger messes with the program counter, it clears
 538          * the software "in syscall" bit, directing us to not perform
 539          * a syscall restart.
 540          */
 541         if (restart_syscall && !pt_regs_is_syscall(regs))
 542                 restart_syscall = 0;
 543
 544         if (signr > 0) {
 545                 if (restart_syscall)
 546                         syscall_restart(orig_i0, regs, &ka.sa);
 547                 handle_signal(signr, &ka, &info, oldset, regs);
 548
 549                 /* a signal was successfully delivered; the saved
 550                  * sigmask will have been stored in the signal frame,
 551                  * and will be restored by sigreturn, so we can simply
 552                  * clear the TIF_RESTORE_SIGMASK flag.
 553                  */
 554                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 555                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 556
 557                 tracehook_signal_handler(signr, &info, &ka, regs, 0);
 558                 return;
 559         }
 560         if (restart_syscall &&
 561             (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
 562              regs->u_regs[UREG_I0] == ERESTARTSYS ||
 563              regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
 564                 /* replay the system call when we are done */
 565                 regs->u_regs[UREG_I0] = orig_i0;
 566                 regs->pc -= 4;
 567                 regs->npc -= 4;
 568         }
 569         if (restart_syscall &&
 570             regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
 571                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
 572                 regs->pc -= 4;
 573                 regs->npc -= 4;
 574         }
 575
 576         /* if there's no signal to deliver, we just put the saved sigmask
 577          * back
 578          */
 579         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 580                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 581                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 582         }
 583 }
 584
 585 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
 586                       unsigned long thread_info_flags)
 587 {
 588         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 589                 do_signal(regs, orig_i0);
 590         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 591                 clear_thread_flag(TIF_NOTIFY_RESUME);
 592                 tracehook_notify_resume(regs);
 593         }
 594 }
 595
 596 asmlinkage int
 597 do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
 598                 unsigned long sp)
 599 {
 600         int ret = -EFAULT;
 601
 602         /* First see if old state is wanted. */
 603         if (ossptr) {
 604                 if (put_user(current->sas_ss_sp + current->sas_ss_size,
 605                              &ossptr->the_stack) ||
 606                     __put_user(on_sig_stack(sp), &ossptr->cur_status))
 607                         goto out;
 608         }
 609
 610         /* Now see if we want to update the new state. */
 611         if (ssptr) {
 612                 char *ss_sp;
 613
 614                 if (get_user(ss_sp, &ssptr->the_stack))
 615                         goto out;
 616                 /* If the current stack was set with sigaltstack, don't
 617                    swap stacks while we are on it.  */
 618                 ret = -EPERM;
 619                 if (current->sas_ss_sp && on_sig_stack(sp))
 620                         goto out;
 621
 622                 /* Since we don't know the extent of the stack, and we don't
 623                    track onstack-ness, but rather calculate it, we must
 624                    presume a size.  Ho hum this interface is lossy.  */
 625                 current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
 626                 current->sas_ss_size = SIGSTKSZ;
 627         }
 628         ret = 0;
 629 out:
 630         return ret;
 631 }