arch/mips/kernel/signal.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1991, 1992  Linus Torvalds
   7  * Copyright (C) 1994 - 2000  Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  */
  10 #include <linux/cache.h>
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13 #include <linux/personality.h>
  14 #include <linux/smp.h>
  15 #include <linux/kernel.h>
  16 #include <linux/signal.h>
  17 #include <linux/errno.h>
  18 #include <linux/wait.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/unistd.h>
  21 #include <linux/compiler.h>
  22 #include <linux/uaccess.h>
  23
  24 #include <asm/abi.h>
  25 #include <asm/asm.h>
  26 #include <linux/bitops.h>
  27 #include <asm/cacheflush.h>
  28 #include <asm/fpu.h>
  29 #include <asm/sim.h>
  30 #include <asm/ucontext.h>
  31 #include <asm/cpu-features.h>
  32 #include <asm/war.h>
  33
  34 #include "signal-common.h"
  35
  36 /*
  37  * Horribly complicated - with the bloody RM9000 workarounds enabled
  38  * the signal trampolines is moving to the end of the structure so we can
  39  * increase the alignment without breaking software compatibility.
  40  */
  41 #if ICACHE_REFILLS_WORKAROUND_WAR == 0
  42
  43 struct sigframe {
  44         u32 sf_ass[4];          /* argument save space for o32 */
  45         u32 sf_code[2];         /* signal trampoline */
  46         struct sigcontext sf_sc;
  47         sigset_t sf_mask;
  48 };
  49
  50 struct rt_sigframe {
  51         u32 rs_ass[4];          /* argument save space for o32 */
  52         u32 rs_code[2];         /* signal trampoline */
  53         struct siginfo rs_info;
  54         struct ucontext rs_uc;
  55 };
  56
  57 #else
  58
  59 struct sigframe {
  60         u32 sf_ass[4];                  /* argument save space for o32 */
  61         u32 sf_pad[2];
  62         struct sigcontext sf_sc;        /* hw context */
  63         sigset_t sf_mask;
  64         u32 sf_code[8] ____cacheline_aligned;   /* signal trampoline */
  65 };
  66
  67 struct rt_sigframe {
  68         u32 rs_ass[4];                  /* argument save space for o32 */
  69         u32 rs_pad[2];
  70         struct siginfo rs_info;
  71         struct ucontext rs_uc;
  72         u32 rs_code[8] ____cacheline_aligned;   /* signal trampoline */
  73 };
  74
  75 #endif
  76
  77 /*
  78  * Helper routines
  79  */
  80 static int protected_save_fp_context(struct sigcontext __user *sc)
  81 {
  82         int err;
  83         while (1) {
  84                 lock_fpu_owner();
  85                 own_fpu_inatomic(1);
  86                 err = save_fp_context(sc); /* this might fail */
  87                 unlock_fpu_owner();
  88                 if (likely(!err))
  89                         break;
  90                 /* touch the sigcontext and try again */
  91                 err = __put_user(0, &sc->sc_fpregs[0]) |
  92                         __put_user(0, &sc->sc_fpregs[31]) |
  93                         __put_user(0, &sc->sc_fpc_csr);
  94                 if (err)
  95                         break;  /* really bad sigcontext */
  96         }
  97         return err;
  98 }
  99
 100 static int protected_restore_fp_context(struct sigcontext __user *sc)
 101 {
 102         int err, tmp;
 103         while (1) {
 104                 lock_fpu_owner();
 105                 own_fpu_inatomic(0);
 106                 err = restore_fp_context(sc); /* this might fail */
 107                 unlock_fpu_owner();
 108                 if (likely(!err))
 109                         break;
 110                 /* touch the sigcontext and try again */
 111                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
 112                         __get_user(tmp, &sc->sc_fpregs[31]) |
 113                         __get_user(tmp, &sc->sc_fpc_csr);
 114                 if (err)
 115                         break;  /* really bad sigcontext */
 116         }
 117         return err;
 118 }
 119
 120 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 121 {
 122         int err = 0;
 123         int i;
 124         unsigned int used_math;
 125
 126         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 127
 128         err |= __put_user(0, &sc->sc_regs[0]);
 129         for (i = 1; i < 32; i++)
 130                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 131
 132 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 133         err |= __put_user(regs->acx, &sc->sc_acx);
 134 #endif
 135         err |= __put_user(regs->hi, &sc->sc_mdhi);
 136         err |= __put_user(regs->lo, &sc->sc_mdlo);
 137         if (cpu_has_dsp) {
 138                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 139                 err |= __put_user(mflo1(), &sc->sc_lo1);
 140                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 141                 err |= __put_user(mflo2(), &sc->sc_lo2);
 142                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 143                 err |= __put_user(mflo3(), &sc->sc_lo3);
 144                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 145         }
 146
 147         used_math = !!used_math();
 148         err |= __put_user(used_math, &sc->sc_used_math);
 149
 150         if (used_math) {
 151                 /*
 152                  * Save FPU state to signal context. Signal handler
 153                  * will "inherit" current FPU state.
 154                  */
 155                 err |= protected_save_fp_context(sc);
 156         }
 157         return err;
 158 }
 159
 160 int fpcsr_pending(unsigned int __user *fpcsr)
 161 {
 162         int err, sig = 0;
 163         unsigned int csr, enabled;
 164
 165         err = __get_user(csr, fpcsr);
 166         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 167         /*
 168          * If the signal handler set some FPU exceptions, clear it and
 169          * send SIGFPE.
 170          */
 171         if (csr & enabled) {
 172                 csr &= ~enabled;
 173                 err |= __put_user(csr, fpcsr);
 174                 sig = SIGFPE;
 175         }
 176         return err ?: sig;
 177 }
 178
 179 static int
 180 check_and_restore_fp_context(struct sigcontext __user *sc)
 181 {
 182         int err, sig;
 183
 184         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 185         if (err > 0)
 186                 err = 0;
 187         err |= protected_restore_fp_context(sc);
 188         return err ?: sig;
 189 }
 190
 191 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 192 {
 193         unsigned int used_math;
 194         unsigned long treg;
 195         int err = 0;
 196         int i;
 197
 198         /* Always make any pending restarted system calls return -EINTR */
 199         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 200
 201         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 202
 203 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 204         err |= __get_user(regs->acx, &sc->sc_acx);
 205 #endif
 206         err |= __get_user(regs->hi, &sc->sc_mdhi);
 207         err |= __get_user(regs->lo, &sc->sc_mdlo);
 208         if (cpu_has_dsp) {
 209                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 210                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 211                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 212                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 213                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 214                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 215                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 216         }
 217
 218         for (i = 1; i < 32; i++)
 219                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 220
 221         err |= __get_user(used_math, &sc->sc_used_math);
 222         conditional_used_math(used_math);
 223
 224         if (used_math) {
 225                 /* restore fpu context if we have used it before */
 226                 if (!err)
 227                         err = check_and_restore_fp_context(sc);
 228         } else {
 229                 /* signal handler may have used FPU.  Give it up. */
 230                 lose_fpu(0);
 231         }
 232
 233         return err;
 234 }
 235
 236 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 237                           size_t frame_size)
 238 {
 239         unsigned long sp;
 240
 241         /* Default to using normal stack */
 242         sp = regs->regs[29];
 243
 244         /*
 245          * FPU emulator may have it's own trampoline active just
 246          * above the user stack, 16-bytes before the next lowest
 247          * 16 byte boundary.  Try to avoid trashing it.
 248          */
 249         sp -= 32;
 250
 251         /* This is the X/Open sanctioned signal stack switching.  */
 252         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 253                 sp = current->sas_ss_sp + current->sas_ss_size;
 254
 255         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 256 }
 257
 258 int install_sigtramp(unsigned int __user *tramp, unsigned int syscall)
 259 {
 260         int err;
 261
 262         /*
 263          * Set up the return code ...
 264          *
 265          *         li      v0, __NR__foo_sigreturn
 266          *         syscall
 267          */
 268
 269         err = __put_user(0x24020000 + syscall, tramp + 0);
 270         err |= __put_user(0x0000000c         , tramp + 1);
 271         if (ICACHE_REFILLS_WORKAROUND_WAR) {
 272                 err |= __put_user(0, tramp + 2);
 273                 err |= __put_user(0, tramp + 3);
 274                 err |= __put_user(0, tramp + 4);
 275                 err |= __put_user(0, tramp + 5);
 276                 err |= __put_user(0, tramp + 6);
 277                 err |= __put_user(0, tramp + 7);
 278         }
 279         flush_cache_sigtramp((unsigned long) tramp);
 280
 281         return err;
 282 }
 283
 284 /*
 285  * Atomically swap in the new signal mask, and wait for a signal.
 286  */
 287
 288 #ifdef CONFIG_TRAD_SIGNALS
 289 asmlinkage int sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
 290 {
 291         sigset_t newset;
 292         sigset_t __user *uset;
 293
 294         uset = (sigset_t __user *) regs.regs[4];
 295         if (copy_from_user(&newset, uset, sizeof(sigset_t)))
 296                 return -EFAULT;
 297         sigdelsetmask(&newset, ~_BLOCKABLE);
 298
 299         spin_lock_irq(&current->sighand->siglock);
 300         current->saved_sigmask = current->blocked;
 301         current->blocked = newset;
 302         recalc_sigpending();
 303         spin_unlock_irq(&current->sighand->siglock);
 304
 305         current->state = TASK_INTERRUPTIBLE;
 306         schedule();
 307         set_thread_flag(TIF_RESTORE_SIGMASK);
 308         return -ERESTARTNOHAND;
 309 }
 310 #endif
 311
 312 asmlinkage int sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
 313 {
 314         sigset_t newset;
 315         sigset_t __user *unewset;
 316         size_t sigsetsize;
 317
 318         /* XXX Don't preclude handling different sized sigset_t's.  */
 319         sigsetsize = regs.regs[5];
 320         if (sigsetsize != sizeof(sigset_t))
 321                 return -EINVAL;
 322
 323         unewset = (sigset_t __user *) regs.regs[4];
 324         if (copy_from_user(&newset, unewset, sizeof(newset)))
 325                 return -EFAULT;
 326         sigdelsetmask(&newset, ~_BLOCKABLE);
 327
 328         spin_lock_irq(&current->sighand->siglock);
 329         current->saved_sigmask = current->blocked;
 330         current->blocked = newset;
 331         recalc_sigpending();
 332         spin_unlock_irq(&current->sighand->siglock);
 333
 334         current->state = TASK_INTERRUPTIBLE;
 335         schedule();
 336         set_thread_flag(TIF_RESTORE_SIGMASK);
 337         return -ERESTARTNOHAND;
 338 }
 339
 340 #ifdef CONFIG_TRAD_SIGNALS
 341 asmlinkage int sys_sigaction(int sig, const struct sigaction __user *act,
 342         struct sigaction __user *oact)
 343 {
 344         struct k_sigaction new_ka, old_ka;
 345         int ret;
 346         int err = 0;
 347
 348         if (act) {
 349                 old_sigset_t mask;
 350
 351                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 352                         return -EFAULT;
 353                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 354                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 355                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 356                 if (err)
 357                         return -EFAULT;
 358
 359                 siginitset(&new_ka.sa.sa_mask, mask);
 360         }
 361
 362         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 363
 364         if (!ret && oact) {
 365                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 366                         return -EFAULT;
 367                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 368                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 369                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 370                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 371                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 372                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 373                 if (err)
 374                         return -EFAULT;
 375         }
 376
 377         return ret;
 378 }
 379 #endif
 380
 381 asmlinkage int sys_sigaltstack(nabi_no_regargs struct pt_regs regs)
 382 {
 383         const stack_t __user *uss = (const stack_t __user *) regs.regs[4];
 384         stack_t __user *uoss = (stack_t __user *) regs.regs[5];
 385         unsigned long usp = regs.regs[29];
 386
 387         return do_sigaltstack(uss, uoss, usp);
 388 }
 389
 390 #ifdef CONFIG_TRAD_SIGNALS
 391 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 392 {
 393         struct sigframe __user *frame;
 394         sigset_t blocked;
 395         int sig;
 396
 397         frame = (struct sigframe __user *) regs.regs[29];
 398         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 399                 goto badframe;
 400         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 401                 goto badframe;
 402
 403         sigdelsetmask(&blocked, ~_BLOCKABLE);
 404         spin_lock_irq(&current->sighand->siglock);
 405         current->blocked = blocked;
 406         recalc_sigpending();
 407         spin_unlock_irq(&current->sighand->siglock);
 408
 409         sig = restore_sigcontext(&regs, &frame->sf_sc);
 410         if (sig < 0)
 411                 goto badframe;
 412         else if (sig)
 413                 force_sig(sig, current);
 414
 415         /*
 416          * Don't let your children do this ...
 417          */
 418         __asm__ __volatile__(
 419                 "move\t$29, %0\n\t"
 420                 "j\tsyscall_exit"
 421                 :/* no outputs */
 422                 :"r" (&regs));
 423         /* Unreached */
 424
 425 badframe:
 426         force_sig(SIGSEGV, current);
 427 }
 428 #endif /* CONFIG_TRAD_SIGNALS */
 429
 430 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 431 {
 432         struct rt_sigframe __user *frame;
 433         sigset_t set;
 434         stack_t st;
 435         int sig;
 436
 437         frame = (struct rt_sigframe __user *) regs.regs[29];
 438         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 439                 goto badframe;
 440         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 441                 goto badframe;
 442
 443         sigdelsetmask(&set, ~_BLOCKABLE);
 444         spin_lock_irq(&current->sighand->siglock);
 445         current->blocked = set;
 446         recalc_sigpending();
 447         spin_unlock_irq(&current->sighand->siglock);
 448
 449         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 450         if (sig < 0)
 451                 goto badframe;
 452         else if (sig)
 453                 force_sig(sig, current);
 454
 455         if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
 456                 goto badframe;
 457         /* It is more difficult to avoid calling this function than to
 458            call it and ignore errors.  */
 459         do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
 460
 461         /*
 462          * Don't let your children do this ...
 463          */
 464         __asm__ __volatile__(
 465                 "move\t$29, %0\n\t"
 466                 "j\tsyscall_exit"
 467                 :/* no outputs */
 468                 :"r" (&regs));
 469         /* Unreached */
 470
 471 badframe:
 472         force_sig(SIGSEGV, current);
 473 }
 474
 475 #ifdef CONFIG_TRAD_SIGNALS
 476 static int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
 477         int signr, sigset_t *set)
 478 {
 479         struct sigframe __user *frame;
 480         int err = 0;
 481
 482         frame = get_sigframe(ka, regs, sizeof(*frame));
 483         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 484                 goto give_sigsegv;
 485
 486         err |= install_sigtramp(frame->sf_code, __NR_sigreturn);
 487
 488         err |= setup_sigcontext(regs, &frame->sf_sc);
 489         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 490         if (err)
 491                 goto give_sigsegv;
 492
 493         /*
 494          * Arguments to signal handler:
 495          *
 496          *   a0 = signal number
 497          *   a1 = 0 (should be cause)
 498          *   a2 = pointer to struct sigcontext
 499          *
 500          * $25 and c0_epc point to the signal handler, $29 points to the
 501          * struct sigframe.
 502          */
 503         regs->regs[ 4] = signr;
 504         regs->regs[ 5] = 0;
 505         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 506         regs->regs[29] = (unsigned long) frame;
 507         regs->regs[31] = (unsigned long) frame->sf_code;
 508         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 509
 510         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 511                current->comm, current->pid,
 512                frame, regs->cp0_epc, regs->regs[31]);
 513         return 0;
 514
 515 give_sigsegv:
 516         force_sigsegv(signr, current);
 517         return -EFAULT;
 518 }
 519 #endif
 520
 521 static int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
 522         int signr, sigset_t *set, siginfo_t *info)
 523 {
 524         struct rt_sigframe __user *frame;
 525         int err = 0;
 526
 527         frame = get_sigframe(ka, regs, sizeof(*frame));
 528         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 529                 goto give_sigsegv;
 530
 531         err |= install_sigtramp(frame->rs_code, __NR_rt_sigreturn);
 532
 533         /* Create siginfo.  */
 534         err |= copy_siginfo_to_user(&frame->rs_info, info);
 535
 536         /* Create the ucontext.  */
 537         err |= __put_user(0, &frame->rs_uc.uc_flags);
 538         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 539         err |= __put_user((void __user *)current->sas_ss_sp,
 540                           &frame->rs_uc.uc_stack.ss_sp);
 541         err |= __put_user(sas_ss_flags(regs->regs[29]),
 542                           &frame->rs_uc.uc_stack.ss_flags);
 543         err |= __put_user(current->sas_ss_size,
 544                           &frame->rs_uc.uc_stack.ss_size);
 545         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 546         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 547
 548         if (err)
 549                 goto give_sigsegv;
 550
 551         /*
 552          * Arguments to signal handler:
 553          *
 554          *   a0 = signal number
 555          *   a1 = 0 (should be cause)
 556          *   a2 = pointer to ucontext
 557          *
 558          * $25 and c0_epc point to the signal handler, $29 points to
 559          * the struct rt_sigframe.
 560          */
 561         regs->regs[ 4] = signr;
 562         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 563         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 564         regs->regs[29] = (unsigned long) frame;
 565         regs->regs[31] = (unsigned long) frame->rs_code;
 566         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 567
 568         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 569                current->comm, current->pid,
 570                frame, regs->cp0_epc, regs->regs[31]);
 571
 572         return 0;
 573
 574 give_sigsegv:
 575         force_sigsegv(signr, current);
 576         return -EFAULT;
 577 }
 578
 579 struct mips_abi mips_abi = {
 580 #ifdef CONFIG_TRAD_SIGNALS
 581         .setup_frame    = setup_frame,
 582 #endif
 583         .setup_rt_frame = setup_rt_frame,
 584         .restart        = __NR_restart_syscall
 585 };
 586
 587 static int handle_signal(unsigned long sig, siginfo_t *info,
 588         struct k_sigaction *ka, sigset_t *oldset, struct pt_regs *regs)
 589 {
 590         int ret;
 591
 592         switch(regs->regs[0]) {
 593         case ERESTART_RESTARTBLOCK:
 594         case ERESTARTNOHAND:
 595                 regs->regs[2] = EINTR;
 596                 break;
 597         case ERESTARTSYS:
 598                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 599                         regs->regs[2] = EINTR;
 600                         break;
 601                 }
 602         /* fallthrough */
 603         case ERESTARTNOINTR:            /* Userland will reload $v0.  */
 604                 regs->regs[7] = regs->regs[26];
 605                 regs->cp0_epc -= 8;
 606         }
 607
 608         regs->regs[0] = 0;              /* Don't deal with this again.  */
 609
 610         if (sig_uses_siginfo(ka))
 611                 ret = current->thread.abi->setup_rt_frame(ka, regs, sig, oldset, info);
 612         else
 613                 ret = current->thread.abi->setup_frame(ka, regs, sig, oldset);
 614
 615         spin_lock_irq(&current->sighand->siglock);
 616         sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 617         if (!(ka->sa.sa_flags & SA_NODEFER))
 618                 sigaddset(&current->blocked, sig);
 619         recalc_sigpending();
 620         spin_unlock_irq(&current->sighand->siglock);
 621
 622         return ret;
 623 }
 624
 625 static void do_signal(struct pt_regs *regs)
 626 {
 627         struct k_sigaction ka;
 628         sigset_t *oldset;
 629         siginfo_t info;
 630         int signr;
 631
 632         /*
 633          * We want the common case to go fast, which is why we may in certain
 634          * cases get here from kernel mode. Just return without doing anything
 635          * if so.
 636          */
 637         if (!user_mode(regs))
 638                 return;
 639
 640         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 641                 oldset = &current->saved_sigmask;
 642         else
 643                 oldset = &current->blocked;
 644
 645         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 646         if (signr > 0) {
 647                 /* Whee!  Actually deliver the signal.  */
 648                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 649                         /*
 650                          * A signal was successfully delivered; the saved
 651                          * sigmask will have been stored in the signal frame,
 652                          * and will be restored by sigreturn, so we can simply
 653                          * clear the TIF_RESTORE_SIGMASK flag.
 654                          */
 655                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 656                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 657                 }
 658
 659                 return;
 660         }
 661
 662         /*
 663          * Who's code doesn't conform to the restartable syscall convention
 664          * dies here!!!  The li instruction, a single machine instruction,
 665          * must directly be followed by the syscall instruction.
 666          */
 667         if (regs->regs[0]) {
 668                 if (regs->regs[2] == ERESTARTNOHAND ||
 669                     regs->regs[2] == ERESTARTSYS ||
 670                     regs->regs[2] == ERESTARTNOINTR) {
 671                         regs->regs[7] = regs->regs[26];
 672                         regs->cp0_epc -= 8;
 673                 }
 674                 if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
 675                         regs->regs[2] = current->thread.abi->restart;
 676                         regs->regs[7] = regs->regs[26];
 677                         regs->cp0_epc -= 4;
 678                 }
 679                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 680         }
 681
 682         /*
 683          * If there's no signal to deliver, we just put the saved sigmask
 684          * back
 685          */
 686         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 687                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 688                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 689         }
 690 }
 691
 692 /*
 693  * notification of userspace execution resumption
 694  * - triggered by the TIF_WORK_MASK flags
 695  */
 696 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 697         __u32 thread_info_flags)
 698 {
 699         /* deal with pending signal delivery */
 700         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 701                 do_signal(regs);
 702 }