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/smp_lock.h>
  16 #include <linux/kernel.h>
  17 #include <linux/signal.h>
  18 #include <linux/errno.h>
  19 #include <linux/wait.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/unistd.h>
  22 #include <linux/compiler.h>
  23 #include <linux/uaccess.h>
  24
  25 #include <asm/abi.h>
  26 #include <asm/asm.h>
  27 #include <linux/bitops.h>
  28 #include <asm/cacheflush.h>
  29 #include <asm/fpu.h>
  30 #include <asm/sim.h>
  31 #include <asm/ucontext.h>
  32 #include <asm/cpu-features.h>
  33 #include <asm/war.h>
  34
  35 #include "signal-common.h"
  36
  37 /*
  38  * Horribly complicated - with the bloody RM9000 workarounds enabled
  39  * the signal trampolines is moving to the end of the structure so we can
  40  * increase the alignment without breaking software compatibility.
  41  */
  42 #if ICACHE_REFILLS_WORKAROUND_WAR == 0
  43
  44 struct sigframe {
  45         u32 sf_ass[4];          /* argument save space for o32 */
  46         u32 sf_code[2];         /* signal trampoline */
  47         struct sigcontext sf_sc;
  48         sigset_t sf_mask;
  49 };
  50
  51 struct rt_sigframe {
  52         u32 rs_ass[4];          /* argument save space for o32 */
  53         u32 rs_code[2];         /* signal trampoline */
  54         struct siginfo rs_info;
  55         struct ucontext rs_uc;
  56 };
  57
  58 #else
  59
  60 struct sigframe {
  61         u32 sf_ass[4];                  /* argument save space for o32 */
  62         u32 sf_pad[2];
  63         struct sigcontext sf_sc;        /* hw context */
  64         sigset_t sf_mask;
  65         u32 sf_code[8] ____cacheline_aligned;   /* signal trampoline */
  66 };
  67
  68 struct rt_sigframe {
  69         u32 rs_ass[4];                  /* argument save space for o32 */
  70         u32 rs_pad[2];
  71         struct siginfo rs_info;
  72         struct ucontext rs_uc;
  73         u32 rs_code[8] ____cacheline_aligned;   /* signal trampoline */
  74 };
  75
  76 #endif
  77
  78 /*
  79  * Helper routines
  80  */
  81 static int protected_save_fp_context(struct sigcontext __user *sc)
  82 {
  83         int err;
  84         while (1) {
  85                 lock_fpu_owner();
  86                 own_fpu_inatomic(1);
  87                 err = save_fp_context(sc); /* this might fail */
  88                 unlock_fpu_owner();
  89                 if (likely(!err))
  90                         break;
  91                 /* touch the sigcontext and try again */
  92                 err = __put_user(0, &sc->sc_fpregs[0]) |
  93                         __put_user(0, &sc->sc_fpregs[31]) |
  94                         __put_user(0, &sc->sc_fpc_csr);
  95                 if (err)
  96                         break;  /* really bad sigcontext */
  97         }
  98         return err;
  99 }
 100
 101 static int protected_restore_fp_context(struct sigcontext __user *sc)
 102 {
 103         int err, tmp;
 104         while (1) {
 105                 lock_fpu_owner();
 106                 own_fpu_inatomic(0);
 107                 err = restore_fp_context(sc); /* this might fail */
 108                 unlock_fpu_owner();
 109                 if (likely(!err))
 110                         break;
 111                 /* touch the sigcontext and try again */
 112                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
 113                         __get_user(tmp, &sc->sc_fpregs[31]) |
 114                         __get_user(tmp, &sc->sc_fpc_csr);
 115                 if (err)
 116                         break;  /* really bad sigcontext */
 117         }
 118         return err;
 119 }
 120
 121 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 122 {
 123         int err = 0;
 124         int i;
 125         unsigned int used_math;
 126
 127         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 128
 129         err |= __put_user(0, &sc->sc_regs[0]);
 130         for (i = 1; i < 32; i++)
 131                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 132
 133 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 134         err |= __put_user(regs->acx, &sc->sc_acx);
 135 #endif
 136         err |= __put_user(regs->hi, &sc->sc_mdhi);
 137         err |= __put_user(regs->lo, &sc->sc_mdlo);
 138         if (cpu_has_dsp) {
 139                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 140                 err |= __put_user(mflo1(), &sc->sc_lo1);
 141                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 142                 err |= __put_user(mflo2(), &sc->sc_lo2);
 143                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 144                 err |= __put_user(mflo3(), &sc->sc_lo3);
 145                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 146         }
 147
 148         used_math = !!used_math();
 149         err |= __put_user(used_math, &sc->sc_used_math);
 150
 151         if (used_math) {
 152                 /*
 153                  * Save FPU state to signal context. Signal handler
 154                  * will "inherit" current FPU state.
 155                  */
 156                 err |= protected_save_fp_context(sc);
 157         }
 158         return err;
 159 }
 160
 161 int fpcsr_pending(unsigned int __user *fpcsr)
 162 {
 163         int err, sig = 0;
 164         unsigned int csr, enabled;
 165
 166         err = __get_user(csr, fpcsr);
 167         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 168         /*
 169          * If the signal handler set some FPU exceptions, clear it and
 170          * send SIGFPE.
 171          */
 172         if (csr & enabled) {
 173                 csr &= ~enabled;
 174                 err |= __put_user(csr, fpcsr);
 175                 sig = SIGFPE;
 176         }
 177         return err ?: sig;
 178 }
 179
 180 static int
 181 check_and_restore_fp_context(struct sigcontext __user *sc)
 182 {
 183         int err, sig;
 184
 185         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 186         if (err > 0)
 187                 err = 0;
 188         err |= protected_restore_fp_context(sc);
 189         return err ?: sig;
 190 }
 191
 192 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 193 {
 194         unsigned int used_math;
 195         unsigned long treg;
 196         int err = 0;
 197         int i;
 198
 199         /* Always make any pending restarted system calls return -EINTR */
 200         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 201
 202         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 203
 204 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 205         err |= __get_user(regs->acx, &sc->sc_acx);
 206 #endif
 207         err |= __get_user(regs->hi, &sc->sc_mdhi);
 208         err |= __get_user(regs->lo, &sc->sc_mdlo);
 209         if (cpu_has_dsp) {
 210                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 211                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 212                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 213                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 214                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 215                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 216                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 217         }
 218
 219         for (i = 1; i < 32; i++)
 220                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 221
 222         err |= __get_user(used_math, &sc->sc_used_math);
 223         conditional_used_math(used_math);
 224
 225         if (used_math) {
 226                 /* restore fpu context if we have used it before */
 227                 if (!err)
 228                         err = check_and_restore_fp_context(sc);
 229         } else {
 230                 /* signal handler may have used FPU.  Give it up. */
 231                 lose_fpu(0);
 232         }
 233
 234         return err;
 235 }
 236
 237 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 238                           size_t frame_size)
 239 {
 240         unsigned long sp;
 241
 242         /* Default to using normal stack */
 243         sp = regs->regs[29];
 244
 245         /*
 246          * FPU emulator may have it's own trampoline active just
 247          * above the user stack, 16-bytes before the next lowest
 248          * 16 byte boundary.  Try to avoid trashing it.
 249          */
 250         sp -= 32;
 251
 252         /* This is the X/Open sanctioned signal stack switching.  */
 253         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 254                 sp = current->sas_ss_sp + current->sas_ss_size;
 255
 256         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 257 }
 258
 259 int install_sigtramp(unsigned int __user *tramp, unsigned int syscall)
 260 {
 261         int err;
 262
 263         /*
 264          * Set up the return code ...
 265          *
 266          *         li      v0, __NR__foo_sigreturn
 267          *         syscall
 268          */
 269
 270         err = __put_user(0x24020000 + syscall, tramp + 0);
 271         err |= __put_user(0x0000000c         , tramp + 1);
 272         if (ICACHE_REFILLS_WORKAROUND_WAR) {
 273                 err |= __put_user(0, tramp + 2);
 274                 err |= __put_user(0, tramp + 3);
 275                 err |= __put_user(0, tramp + 4);
 276                 err |= __put_user(0, tramp + 5);
 277                 err |= __put_user(0, tramp + 6);
 278                 err |= __put_user(0, tramp + 7);
 279         }
 280         flush_cache_sigtramp((unsigned long) tramp);
 281
 282         return err;
 283 }
 284
 285 /*
 286  * Atomically swap in the new signal mask, and wait for a signal.
 287  */
 288
 289 #ifdef CONFIG_TRAD_SIGNALS
 290 asmlinkage int sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
 291 {
 292         sigset_t newset;
 293         sigset_t __user *uset;
 294
 295         uset = (sigset_t __user *) regs.regs[4];
 296         if (copy_from_user(&newset, uset, sizeof(sigset_t)))
 297                 return -EFAULT;
 298         sigdelsetmask(&newset, ~_BLOCKABLE);
 299
 300         spin_lock_irq(&current->sighand->siglock);
 301         current->saved_sigmask = current->blocked;
 302         current->blocked = newset;
 303         recalc_sigpending();
 304         spin_unlock_irq(&current->sighand->siglock);
 305
 306         current->state = TASK_INTERRUPTIBLE;
 307         schedule();
 308         set_thread_flag(TIF_RESTORE_SIGMASK);
 309         return -ERESTARTNOHAND;
 310 }
 311 #endif
 312
 313 asmlinkage int sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
 314 {
 315         sigset_t newset;
 316         sigset_t __user *unewset;
 317         size_t sigsetsize;
 318
 319         /* XXX Don't preclude handling different sized sigset_t's.  */
 320         sigsetsize = regs.regs[5];
 321         if (sigsetsize != sizeof(sigset_t))
 322                 return -EINVAL;
 323
 324         unewset = (sigset_t __user *) regs.regs[4];
 325         if (copy_from_user(&newset, unewset, sizeof(newset)))
 326                 return -EFAULT;
 327         sigdelsetmask(&newset, ~_BLOCKABLE);
 328
 329         spin_lock_irq(&current->sighand->siglock);
 330         current->saved_sigmask = current->blocked;
 331         current->blocked = newset;
 332         recalc_sigpending();
 333         spin_unlock_irq(&current->sighand->siglock);
 334
 335         current->state = TASK_INTERRUPTIBLE;
 336         schedule();
 337         set_thread_flag(TIF_RESTORE_SIGMASK);
 338         return -ERESTARTNOHAND;
 339 }
 340
 341 #ifdef CONFIG_TRAD_SIGNALS
 342 asmlinkage int sys_sigaction(int sig, const struct sigaction __user *act,
 343         struct sigaction __user *oact)
 344 {
 345         struct k_sigaction new_ka, old_ka;
 346         int ret;
 347         int err = 0;
 348
 349         if (act) {
 350                 old_sigset_t mask;
 351
 352                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 353                         return -EFAULT;
 354                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 355                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 356                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 357                 if (err)
 358                         return -EFAULT;
 359
 360                 siginitset(&new_ka.sa.sa_mask, mask);
 361         }
 362
 363         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 364
 365         if (!ret && oact) {
 366                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 367                         return -EFAULT;
 368                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 369                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 370                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 371                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 372                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 373                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 374                 if (err)
 375                         return -EFAULT;
 376         }
 377
 378         return ret;
 379 }
 380 #endif
 381
 382 asmlinkage int sys_sigaltstack(nabi_no_regargs struct pt_regs regs)
 383 {
 384         const stack_t __user *uss = (const stack_t __user *) regs.regs[4];
 385         stack_t __user *uoss = (stack_t __user *) regs.regs[5];
 386         unsigned long usp = regs.regs[29];
 387
 388         return do_sigaltstack(uss, uoss, usp);
 389 }
 390
 391 #ifdef CONFIG_TRAD_SIGNALS
 392 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 393 {
 394         struct sigframe __user *frame;
 395         sigset_t blocked;
 396         int sig;
 397
 398         frame = (struct sigframe __user *) regs.regs[29];
 399         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 400                 goto badframe;
 401         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 402                 goto badframe;
 403
 404         sigdelsetmask(&blocked, ~_BLOCKABLE);
 405         spin_lock_irq(&current->sighand->siglock);
 406         current->blocked = blocked;
 407         recalc_sigpending();
 408         spin_unlock_irq(&current->sighand->siglock);
 409
 410         sig = restore_sigcontext(&regs, &frame->sf_sc);
 411         if (sig < 0)
 412                 goto badframe;
 413         else if (sig)
 414                 force_sig(sig, current);
 415
 416         /*
 417          * Don't let your children do this ...
 418          */
 419         __asm__ __volatile__(
 420                 "move\t$29, %0\n\t"
 421                 "j\tsyscall_exit"
 422                 :/* no outputs */
 423                 :"r" (&regs));
 424         /* Unreached */
 425
 426 badframe:
 427         force_sig(SIGSEGV, current);
 428 }
 429 #endif /* CONFIG_TRAD_SIGNALS */
 430
 431 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 432 {
 433         struct rt_sigframe __user *frame;
 434         sigset_t set;
 435         stack_t st;
 436         int sig;
 437
 438         frame = (struct rt_sigframe __user *) regs.regs[29];
 439         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 440                 goto badframe;
 441         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 442                 goto badframe;
 443
 444         sigdelsetmask(&set, ~_BLOCKABLE);
 445         spin_lock_irq(&current->sighand->siglock);
 446         current->blocked = set;
 447         recalc_sigpending();
 448         spin_unlock_irq(&current->sighand->siglock);
 449
 450         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 451         if (sig < 0)
 452                 goto badframe;
 453         else if (sig)
 454                 force_sig(sig, current);
 455
 456         if (__copy_from_user(&st, &frame->rs_uc.uc_stack, sizeof(st)))
 457                 goto badframe;
 458         /* It is more difficult to avoid calling this function than to
 459            call it and ignore errors.  */
 460         do_sigaltstack((stack_t __user *)&st, NULL, regs.regs[29]);
 461
 462         /*
 463          * Don't let your children do this ...
 464          */
 465         __asm__ __volatile__(
 466                 "move\t$29, %0\n\t"
 467                 "j\tsyscall_exit"
 468                 :/* no outputs */
 469                 :"r" (&regs));
 470         /* Unreached */
 471
 472 badframe:
 473         force_sig(SIGSEGV, current);
 474 }
 475
 476 #ifdef CONFIG_TRAD_SIGNALS
 477 static int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
 478         int signr, sigset_t *set)
 479 {
 480         struct sigframe __user *frame;
 481         int err = 0;
 482
 483         frame = get_sigframe(ka, regs, sizeof(*frame));
 484         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 485                 goto give_sigsegv;
 486
 487         err |= install_sigtramp(frame->sf_code, __NR_sigreturn);
 488
 489         err |= setup_sigcontext(regs, &frame->sf_sc);
 490         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 491         if (err)
 492                 goto give_sigsegv;
 493
 494         /*
 495          * Arguments to signal handler:
 496          *
 497          *   a0 = signal number
 498          *   a1 = 0 (should be cause)
 499          *   a2 = pointer to struct sigcontext
 500          *
 501          * $25 and c0_epc point to the signal handler, $29 points to the
 502          * struct sigframe.
 503          */
 504         regs->regs[ 4] = signr;
 505         regs->regs[ 5] = 0;
 506         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 507         regs->regs[29] = (unsigned long) frame;
 508         regs->regs[31] = (unsigned long) frame->sf_code;
 509         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 510
 511         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 512                current->comm, current->pid,
 513                frame, regs->cp0_epc, regs->regs[31]);
 514         return 0;
 515
 516 give_sigsegv:
 517         force_sigsegv(signr, current);
 518         return -EFAULT;
 519 }
 520 #endif
 521
 522 static int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
 523         int signr, sigset_t *set, siginfo_t *info)
 524 {
 525         struct rt_sigframe __user *frame;
 526         int err = 0;
 527
 528         frame = get_sigframe(ka, regs, sizeof(*frame));
 529         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 530                 goto give_sigsegv;
 531
 532         err |= install_sigtramp(frame->rs_code, __NR_rt_sigreturn);
 533
 534         /* Create siginfo.  */
 535         err |= copy_siginfo_to_user(&frame->rs_info, info);
 536
 537         /* Create the ucontext.  */
 538         err |= __put_user(0, &frame->rs_uc.uc_flags);
 539         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 540         err |= __put_user((void __user *)current->sas_ss_sp,
 541                           &frame->rs_uc.uc_stack.ss_sp);
 542         err |= __put_user(sas_ss_flags(regs->regs[29]),
 543                           &frame->rs_uc.uc_stack.ss_flags);
 544         err |= __put_user(current->sas_ss_size,
 545                           &frame->rs_uc.uc_stack.ss_size);
 546         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 547         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 548
 549         if (err)
 550                 goto give_sigsegv;
 551
 552         /*
 553          * Arguments to signal handler:
 554          *
 555          *   a0 = signal number
 556          *   a1 = 0 (should be cause)
 557          *   a2 = pointer to ucontext
 558          *
 559          * $25 and c0_epc point to the signal handler, $29 points to
 560          * the struct rt_sigframe.
 561          */
 562         regs->regs[ 4] = signr;
 563         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 564         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 565         regs->regs[29] = (unsigned long) frame;
 566         regs->regs[31] = (unsigned long) frame->rs_code;
 567         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 568
 569         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 570                current->comm, current->pid,
 571                frame, regs->cp0_epc, regs->regs[31]);
 572
 573         return 0;
 574
 575 give_sigsegv:
 576         force_sigsegv(signr, current);
 577         return -EFAULT;
 578 }
 579
 580 struct mips_abi mips_abi = {
 581 #ifdef CONFIG_TRAD_SIGNALS
 582         .setup_frame    = setup_frame,
 583 #endif
 584         .setup_rt_frame = setup_rt_frame,
 585         .restart        = __NR_restart_syscall
 586 };
 587
 588 static int handle_signal(unsigned long sig, siginfo_t *info,
 589         struct k_sigaction *ka, sigset_t *oldset, struct pt_regs *regs)
 590 {
 591         int ret;
 592
 593         switch(regs->regs[0]) {
 594         case ERESTART_RESTARTBLOCK:
 595         case ERESTARTNOHAND:
 596                 regs->regs[2] = EINTR;
 597                 break;
 598         case ERESTARTSYS:
 599                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 600                         regs->regs[2] = EINTR;
 601                         break;
 602                 }
 603         /* fallthrough */
 604         case ERESTARTNOINTR:            /* Userland will reload $v0.  */
 605                 regs->regs[7] = regs->regs[26];
 606                 regs->cp0_epc -= 8;
 607         }
 608
 609         regs->regs[0] = 0;              /* Don't deal with this again.  */
 610
 611         if (sig_uses_siginfo(ka))
 612                 ret = current->thread.abi->setup_rt_frame(ka, regs, sig, oldset, info);
 613         else
 614                 ret = current->thread.abi->setup_frame(ka, regs, sig, oldset);
 615
 616         spin_lock_irq(&current->sighand->siglock);
 617         sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 618         if (!(ka->sa.sa_flags & SA_NODEFER))
 619                 sigaddset(&current->blocked,sig);
 620         recalc_sigpending();
 621         spin_unlock_irq(&current->sighand->siglock);
 622
 623         return ret;
 624 }
 625
 626 static void do_signal(struct pt_regs *regs)
 627 {
 628         struct k_sigaction ka;
 629         sigset_t *oldset;
 630         siginfo_t info;
 631         int signr;
 632
 633         /*
 634          * We want the common case to go fast, which is why we may in certain
 635          * cases get here from kernel mode. Just return without doing anything
 636          * if so.
 637          */
 638         if (!user_mode(regs))
 639                 return;
 640
 641         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 642                 oldset = &current->saved_sigmask;
 643         else
 644                 oldset = &current->blocked;
 645
 646         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 647         if (signr > 0) {
 648                 /* Whee!  Actually deliver the signal.  */
 649                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 650                         /*
 651                          * A signal was successfully delivered; the saved
 652                          * sigmask will have been stored in the signal frame,
 653                          * and will be restored by sigreturn, so we can simply
 654                          * clear the TIF_RESTORE_SIGMASK flag.
 655                          */
 656                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 657                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 658                 }
 659
 660                 return;
 661         }
 662
 663         /*
 664          * Who's code doesn't conform to the restartable syscall convention
 665          * dies here!!!  The li instruction, a single machine instruction,
 666          * must directly be followed by the syscall instruction.
 667          */
 668         if (regs->regs[0]) {
 669                 if (regs->regs[2] == ERESTARTNOHAND ||
 670                     regs->regs[2] == ERESTARTSYS ||
 671                     regs->regs[2] == ERESTARTNOINTR) {
 672                         regs->regs[7] = regs->regs[26];
 673                         regs->cp0_epc -= 8;
 674                 }
 675                 if (regs->regs[2] == ERESTART_RESTARTBLOCK) {
 676                         regs->regs[2] = current->thread.abi->restart;
 677                         regs->regs[7] = regs->regs[26];
 678                         regs->cp0_epc -= 4;
 679                 }
 680                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 681         }
 682
 683         /*
 684          * If there's no signal to deliver, we just put the saved sigmask
 685          * back
 686          */
 687         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 688                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 689                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 690         }
 691 }
 692
 693 /*
 694  * notification of userspace execution resumption
 695  * - triggered by the TIF_WORK_MASK flags
 696  */
 697 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 698         __u32 thread_info_flags)
 699 {
 700         /* deal with pending signal delivery */
 701         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 702                 do_signal(regs);
 703 }