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/irqflags.h>
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/personality.h>
  15 #include <linux/smp.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/syscalls.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/tracehook.h>
  26
  27 #include <asm/abi.h>
  28 #include <asm/asm.h>
  29 #include <linux/bitops.h>
  30 #include <asm/cacheflush.h>
  31 #include <asm/fpu.h>
  32 #include <asm/sim.h>
  33 #include <asm/ucontext.h>
  34 #include <asm/cpu-features.h>
  35 #include <asm/war.h>
  36 #include <asm/vdso.h>
  37 #include <asm/dsp.h>
  38
  39 #include "signal-common.h"
  40
  41 static int (*save_fp_context)(struct sigcontext __user *sc);
  42 static int (*restore_fp_context)(struct sigcontext __user *sc);
  43
  44 extern asmlinkage int _save_fp_context(struct sigcontext __user *sc);
  45 extern asmlinkage int _restore_fp_context(struct sigcontext __user *sc);
  46
  47 extern asmlinkage int fpu_emulator_save_context(struct sigcontext __user *sc);
  48 extern asmlinkage int fpu_emulator_restore_context(struct sigcontext __user *sc);
  49
  50 struct sigframe {
  51         u32 sf_ass[4];          /* argument save space for o32 */
  52         u32 sf_pad[2];          /* Was: signal trampoline */
  53         struct sigcontext sf_sc;
  54         sigset_t sf_mask;
  55 };
  56
  57 struct rt_sigframe {
  58         u32 rs_ass[4];          /* argument save space for o32 */
  59         u32 rs_pad[2];          /* Was: signal trampoline */
  60         struct siginfo rs_info;
  61         struct ucontext rs_uc;
  62 };
  63
  64 /*
  65  * Helper routines
  66  */
  67 static int protected_save_fp_context(struct sigcontext __user *sc)
  68 {
  69         int err;
  70         while (1) {
  71                 lock_fpu_owner();
  72                 own_fpu_inatomic(1);
  73                 err = save_fp_context(sc); /* this might fail */
  74                 unlock_fpu_owner();
  75                 if (likely(!err))
  76                         break;
  77                 /* touch the sigcontext and try again */
  78                 err = __put_user(0, &sc->sc_fpregs[0]) |
  79                         __put_user(0, &sc->sc_fpregs[31]) |
  80                         __put_user(0, &sc->sc_fpc_csr);
  81                 if (err)
  82                         break;  /* really bad sigcontext */
  83         }
  84         return err;
  85 }
  86
  87 static int protected_restore_fp_context(struct sigcontext __user *sc)
  88 {
  89         int err, tmp __maybe_unused;
  90         while (1) {
  91                 lock_fpu_owner();
  92                 own_fpu_inatomic(0);
  93                 err = restore_fp_context(sc); /* this might fail */
  94                 unlock_fpu_owner();
  95                 if (likely(!err))
  96                         break;
  97                 /* touch the sigcontext and try again */
  98                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
  99                         __get_user(tmp, &sc->sc_fpregs[31]) |
 100                         __get_user(tmp, &sc->sc_fpc_csr);
 101                 if (err)
 102                         break;  /* really bad sigcontext */
 103         }
 104         return err;
 105 }
 106
 107 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 108 {
 109         int err = 0;
 110         int i;
 111         unsigned int used_math;
 112
 113         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 114
 115         err |= __put_user(0, &sc->sc_regs[0]);
 116         for (i = 1; i < 32; i++)
 117                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 118
 119 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 120         err |= __put_user(regs->acx, &sc->sc_acx);
 121 #endif
 122         err |= __put_user(regs->hi, &sc->sc_mdhi);
 123         err |= __put_user(regs->lo, &sc->sc_mdlo);
 124         if (cpu_has_dsp) {
 125                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 126                 err |= __put_user(mflo1(), &sc->sc_lo1);
 127                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 128                 err |= __put_user(mflo2(), &sc->sc_lo2);
 129                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 130                 err |= __put_user(mflo3(), &sc->sc_lo3);
 131                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 132         }
 133
 134         used_math = !!used_math();
 135         err |= __put_user(used_math, &sc->sc_used_math);
 136
 137         if (used_math) {
 138                 /*
 139                  * Save FPU state to signal context. Signal handler
 140                  * will "inherit" current FPU state.
 141                  */
 142                 err |= protected_save_fp_context(sc);
 143         }
 144         return err;
 145 }
 146
 147 int fpcsr_pending(unsigned int __user *fpcsr)
 148 {
 149         int err, sig = 0;
 150         unsigned int csr, enabled;
 151
 152         err = __get_user(csr, fpcsr);
 153         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 154         /*
 155          * If the signal handler set some FPU exceptions, clear it and
 156          * send SIGFPE.
 157          */
 158         if (csr & enabled) {
 159                 csr &= ~enabled;
 160                 err |= __put_user(csr, fpcsr);
 161                 sig = SIGFPE;
 162         }
 163         return err ?: sig;
 164 }
 165
 166 static int
 167 check_and_restore_fp_context(struct sigcontext __user *sc)
 168 {
 169         int err, sig;
 170
 171         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 172         if (err > 0)
 173                 err = 0;
 174         err |= protected_restore_fp_context(sc);
 175         return err ?: sig;
 176 }
 177
 178 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 179 {
 180         unsigned int used_math;
 181         unsigned long treg;
 182         int err = 0;
 183         int i;
 184
 185         /* Always make any pending restarted system calls return -EINTR */
 186         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 187
 188         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 189
 190 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 191         err |= __get_user(regs->acx, &sc->sc_acx);
 192 #endif
 193         err |= __get_user(regs->hi, &sc->sc_mdhi);
 194         err |= __get_user(regs->lo, &sc->sc_mdlo);
 195         if (cpu_has_dsp) {
 196                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 197                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 198                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 199                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 200                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 201                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 202                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 203         }
 204
 205         for (i = 1; i < 32; i++)
 206                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 207
 208         err |= __get_user(used_math, &sc->sc_used_math);
 209         conditional_used_math(used_math);
 210
 211         if (used_math) {
 212                 /* restore fpu context if we have used it before */
 213                 if (!err)
 214                         err = check_and_restore_fp_context(sc);
 215         } else {
 216                 /* signal handler may have used FPU.  Give it up. */
 217                 lose_fpu(0);
 218         }
 219
 220         return err;
 221 }
 222
 223 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 224                           size_t frame_size)
 225 {
 226         unsigned long sp;
 227
 228         /* Default to using normal stack */
 229         sp = regs->regs[29];
 230
 231         /*
 232          * FPU emulator may have it's own trampoline active just
 233          * above the user stack, 16-bytes before the next lowest
 234          * 16 byte boundary.  Try to avoid trashing it.
 235          */
 236         sp -= 32;
 237
 238         /* This is the X/Open sanctioned signal stack switching.  */
 239         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 240                 sp = current->sas_ss_sp + current->sas_ss_size;
 241
 242         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 243 }
 244
 245 /*
 246  * Atomically swap in the new signal mask, and wait for a signal.
 247  */
 248
 249 #ifdef CONFIG_TRAD_SIGNALS
 250 asmlinkage int sys_sigsuspend(nabi_no_regargs struct pt_regs regs)
 251 {
 252         sigset_t newset;
 253         sigset_t __user *uset;
 254
 255         uset = (sigset_t __user *) regs.regs[4];
 256         if (copy_from_user(&newset, uset, sizeof(sigset_t)))
 257                 return -EFAULT;
 258         return sigsuspend(&newset);
 259 }
 260 #endif
 261
 262 asmlinkage int sys_rt_sigsuspend(nabi_no_regargs struct pt_regs regs)
 263 {
 264         sigset_t newset;
 265         sigset_t __user *unewset;
 266         size_t sigsetsize;
 267
 268         /* XXX Don't preclude handling different sized sigset_t's.  */
 269         sigsetsize = regs.regs[5];
 270         if (sigsetsize != sizeof(sigset_t))
 271                 return -EINVAL;
 272
 273         unewset = (sigset_t __user *) regs.regs[4];
 274         if (copy_from_user(&newset, unewset, sizeof(newset)))
 275                 return -EFAULT;
 276         return sigsuspend(&newset);
 277 }
 278
 279 #ifdef CONFIG_TRAD_SIGNALS
 280 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 281         struct sigaction __user *, oact)
 282 {
 283         struct k_sigaction new_ka, old_ka;
 284         int ret;
 285         int err = 0;
 286
 287         if (act) {
 288                 old_sigset_t mask;
 289
 290                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 291                         return -EFAULT;
 292                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 293                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 294                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 295                 if (err)
 296                         return -EFAULT;
 297
 298                 siginitset(&new_ka.sa.sa_mask, mask);
 299         }
 300
 301         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 302
 303         if (!ret && oact) {
 304                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 305                         return -EFAULT;
 306                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 307                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 308                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 309                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 310                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 311                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 312                 if (err)
 313                         return -EFAULT;
 314         }
 315
 316         return ret;
 317 }
 318 #endif
 319
 320 asmlinkage int sys_sigaltstack(nabi_no_regargs struct pt_regs regs)
 321 {
 322         const stack_t __user *uss = (const stack_t __user *) regs.regs[4];
 323         stack_t __user *uoss = (stack_t __user *) regs.regs[5];
 324         unsigned long usp = regs.regs[29];
 325
 326         return do_sigaltstack(uss, uoss, usp);
 327 }
 328
 329 #ifdef CONFIG_TRAD_SIGNALS
 330 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 331 {
 332         struct sigframe __user *frame;
 333         sigset_t blocked;
 334         int sig;
 335
 336         frame = (struct sigframe __user *) regs.regs[29];
 337         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 338                 goto badframe;
 339         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 340                 goto badframe;
 341
 342         set_current_blocked(&blocked);
 343
 344         sig = restore_sigcontext(&regs, &frame->sf_sc);
 345         if (sig < 0)
 346                 goto badframe;
 347         else if (sig)
 348                 force_sig(sig, current);
 349
 350         /*
 351          * Don't let your children do this ...
 352          */
 353         __asm__ __volatile__(
 354                 "move\t$29, %0\n\t"
 355                 "j\tsyscall_exit"
 356                 :/* no outputs */
 357                 :"r" (&regs));
 358         /* Unreached */
 359
 360 badframe:
 361         force_sig(SIGSEGV, current);
 362 }
 363 #endif /* CONFIG_TRAD_SIGNALS */
 364
 365 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 366 {
 367         struct rt_sigframe __user *frame;
 368         sigset_t set;
 369         int sig;
 370
 371         frame = (struct rt_sigframe __user *) regs.regs[29];
 372         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 373                 goto badframe;
 374         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 375                 goto badframe;
 376
 377         set_current_blocked(&set);
 378
 379         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 380         if (sig < 0)
 381                 goto badframe;
 382         else if (sig)
 383                 force_sig(sig, current);
 384
 385         /* It is more difficult to avoid calling this function than to
 386            call it and ignore errors.  */
 387         do_sigaltstack(&frame->rs_uc.uc_stack, NULL, regs.regs[29]);
 388
 389         /*
 390          * Don't let your children do this ...
 391          */
 392         __asm__ __volatile__(
 393                 "move\t$29, %0\n\t"
 394                 "j\tsyscall_exit"
 395                 :/* no outputs */
 396                 :"r" (&regs));
 397         /* Unreached */
 398
 399 badframe:
 400         force_sig(SIGSEGV, current);
 401 }
 402
 403 #ifdef CONFIG_TRAD_SIGNALS
 404 static int setup_frame(void *sig_return, struct k_sigaction *ka,
 405                        struct pt_regs *regs, int signr, sigset_t *set)
 406 {
 407         struct sigframe __user *frame;
 408         int err = 0;
 409
 410         frame = get_sigframe(ka, regs, sizeof(*frame));
 411         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 412                 goto give_sigsegv;
 413
 414         err |= setup_sigcontext(regs, &frame->sf_sc);
 415         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 416         if (err)
 417                 goto give_sigsegv;
 418
 419         /*
 420          * Arguments to signal handler:
 421          *
 422          *   a0 = signal number
 423          *   a1 = 0 (should be cause)
 424          *   a2 = pointer to struct sigcontext
 425          *
 426          * $25 and c0_epc point to the signal handler, $29 points to the
 427          * struct sigframe.
 428          */
 429         regs->regs[ 4] = signr;
 430         regs->regs[ 5] = 0;
 431         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 432         regs->regs[29] = (unsigned long) frame;
 433         regs->regs[31] = (unsigned long) sig_return;
 434         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 435
 436         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 437                current->comm, current->pid,
 438                frame, regs->cp0_epc, regs->regs[31]);
 439         return 0;
 440
 441 give_sigsegv:
 442         force_sigsegv(signr, current);
 443         return -EFAULT;
 444 }
 445 #endif
 446
 447 static int setup_rt_frame(void *sig_return, struct k_sigaction *ka,
 448                           struct pt_regs *regs, int signr, sigset_t *set,
 449                           siginfo_t *info)
 450 {
 451         struct rt_sigframe __user *frame;
 452         int err = 0;
 453
 454         frame = get_sigframe(ka, regs, sizeof(*frame));
 455         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 456                 goto give_sigsegv;
 457
 458         /* Create siginfo.  */
 459         err |= copy_siginfo_to_user(&frame->rs_info, info);
 460
 461         /* Create the ucontext.  */
 462         err |= __put_user(0, &frame->rs_uc.uc_flags);
 463         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 464         err |= __put_user((void __user *)current->sas_ss_sp,
 465                           &frame->rs_uc.uc_stack.ss_sp);
 466         err |= __put_user(sas_ss_flags(regs->regs[29]),
 467                           &frame->rs_uc.uc_stack.ss_flags);
 468         err |= __put_user(current->sas_ss_size,
 469                           &frame->rs_uc.uc_stack.ss_size);
 470         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 471         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 472
 473         if (err)
 474                 goto give_sigsegv;
 475
 476         /*
 477          * Arguments to signal handler:
 478          *
 479          *   a0 = signal number
 480          *   a1 = 0 (should be cause)
 481          *   a2 = pointer to ucontext
 482          *
 483          * $25 and c0_epc point to the signal handler, $29 points to
 484          * the struct rt_sigframe.
 485          */
 486         regs->regs[ 4] = signr;
 487         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 488         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 489         regs->regs[29] = (unsigned long) frame;
 490         regs->regs[31] = (unsigned long) sig_return;
 491         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 492
 493         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 494                current->comm, current->pid,
 495                frame, regs->cp0_epc, regs->regs[31]);
 496
 497         return 0;
 498
 499 give_sigsegv:
 500         force_sigsegv(signr, current);
 501         return -EFAULT;
 502 }
 503
 504 struct mips_abi mips_abi = {
 505 #ifdef CONFIG_TRAD_SIGNALS
 506         .setup_frame    = setup_frame,
 507         .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
 508 #endif
 509         .setup_rt_frame = setup_rt_frame,
 510         .rt_signal_return_offset =
 511                 offsetof(struct mips_vdso, rt_signal_trampoline),
 512         .restart        = __NR_restart_syscall
 513 };
 514
 515 static void handle_signal(unsigned long sig, siginfo_t *info,
 516         struct k_sigaction *ka, struct pt_regs *regs)
 517 {
 518         sigset_t *oldset = sigmask_to_save();
 519         int ret;
 520         struct mips_abi *abi = current->thread.abi;
 521         void *vdso = current->mm->context.vdso;
 522
 523         if (regs->regs[0]) {
 524                 switch(regs->regs[2]) {
 525                 case ERESTART_RESTARTBLOCK:
 526                 case ERESTARTNOHAND:
 527                         regs->regs[2] = EINTR;
 528                         break;
 529                 case ERESTARTSYS:
 530                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 531                                 regs->regs[2] = EINTR;
 532                                 break;
 533                         }
 534                 /* fallthrough */
 535                 case ERESTARTNOINTR:
 536                         regs->regs[7] = regs->regs[26];
 537                         regs->regs[2] = regs->regs[0];
 538                         regs->cp0_epc -= 4;
 539                 }
 540
 541                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 542         }
 543
 544         if (sig_uses_siginfo(ka))
 545                 ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
 546                                           ka, regs, sig, oldset, info);
 547         else
 548                 ret = abi->setup_frame(vdso + abi->signal_return_offset,
 549                                        ka, regs, sig, oldset);
 550
 551         if (ret)
 552                 return;
 553
 554         signal_delivered(sig, info, ka, regs, 0);
 555 }
 556
 557 static void do_signal(struct pt_regs *regs)
 558 {
 559         struct k_sigaction ka;
 560         siginfo_t info;
 561         int signr;
 562
 563         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 564         if (signr > 0) {
 565                 /* Whee!  Actually deliver the signal.  */
 566                 handle_signal(signr, &info, &ka, regs);
 567                 return;
 568         }
 569
 570         if (regs->regs[0]) {
 571                 switch (regs->regs[2]) {
 572                 case ERESTARTNOHAND:
 573                 case ERESTARTSYS:
 574                 case ERESTARTNOINTR:
 575                         regs->regs[2] = regs->regs[0];
 576                         regs->regs[7] = regs->regs[26];
 577                         regs->cp0_epc -= 4;
 578                         break;
 579
 580                 case ERESTART_RESTARTBLOCK:
 581                         regs->regs[2] = current->thread.abi->restart;
 582                         regs->regs[7] = regs->regs[26];
 583                         regs->cp0_epc -= 4;
 584                         break;
 585                 }
 586                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 587         }
 588
 589         /*
 590          * If there's no signal to deliver, we just put the saved sigmask
 591          * back
 592          */
 593         restore_saved_sigmask();
 594 }
 595
 596 /*
 597  * notification of userspace execution resumption
 598  * - triggered by the TIF_WORK_MASK flags
 599  */
 600 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 601         __u32 thread_info_flags)
 602 {
 603         local_irq_enable();
 604
 605         /* deal with pending signal delivery */
 606         if (thread_info_flags & _TIF_SIGPENDING)
 607                 do_signal(regs);
 608
 609         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 610                 clear_thread_flag(TIF_NOTIFY_RESUME);
 611                 tracehook_notify_resume(regs);
 612         }
 613 }
 614
 615 #ifdef CONFIG_SMP
 616 static int smp_save_fp_context(struct sigcontext __user *sc)
 617 {
 618         return raw_cpu_has_fpu
 619                ? _save_fp_context(sc)
 620                : fpu_emulator_save_context(sc);
 621 }
 622
 623 static int smp_restore_fp_context(struct sigcontext __user *sc)
 624 {
 625         return raw_cpu_has_fpu
 626                ? _restore_fp_context(sc)
 627                : fpu_emulator_restore_context(sc);
 628 }
 629 #endif
 630
 631 static int signal_setup(void)
 632 {
 633 #ifdef CONFIG_SMP
 634         /* For now just do the cpu_has_fpu check when the functions are invoked */
 635         save_fp_context = smp_save_fp_context;
 636         restore_fp_context = smp_restore_fp_context;
 637 #else
 638         if (cpu_has_fpu) {
 639                 save_fp_context = _save_fp_context;
 640                 restore_fp_context = _restore_fp_context;
 641         } else {
 642                 save_fp_context = fpu_emulator_save_context;
 643                 restore_fp_context = fpu_emulator_restore_context;
 644         }
 645 #endif
 646
 647         return 0;
 648 }
 649
 650 arch_initcall(signal_setup);