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 #include <asm/inst.h>
  39
  40 #include "signal-common.h"
  41
  42 static int (*save_fp_context)(struct sigcontext __user *sc);
  43 static int (*restore_fp_context)(struct sigcontext __user *sc);
  44
  45 extern asmlinkage int _save_fp_context(struct sigcontext __user *sc);
  46 extern asmlinkage int _restore_fp_context(struct sigcontext __user *sc);
  47
  48 extern asmlinkage int fpu_emulator_save_context(struct sigcontext __user *sc);
  49 extern asmlinkage int fpu_emulator_restore_context(struct sigcontext __user *sc);
  50
  51 struct sigframe {
  52         u32 sf_ass[4];          /* argument save space for o32 */
  53         u32 sf_pad[2];          /* Was: signal trampoline */
  54         struct sigcontext sf_sc;
  55         sigset_t sf_mask;
  56 };
  57
  58 struct rt_sigframe {
  59         u32 rs_ass[4];          /* argument save space for o32 */
  60         u32 rs_pad[2];          /* Was: signal trampoline */
  61         struct siginfo rs_info;
  62         struct ucontext rs_uc;
  63 };
  64
  65 /*
  66  * Helper routines
  67  */
  68 static int protected_save_fp_context(struct sigcontext __user *sc)
  69 {
  70         int err;
  71         while (1) {
  72                 lock_fpu_owner();
  73                 own_fpu_inatomic(1);
  74                 err = save_fp_context(sc); /* this might fail */
  75                 unlock_fpu_owner();
  76                 if (likely(!err))
  77                         break;
  78                 /* touch the sigcontext and try again */
  79                 err = __put_user(0, &sc->sc_fpregs[0]) |
  80                         __put_user(0, &sc->sc_fpregs[31]) |
  81                         __put_user(0, &sc->sc_fpc_csr);
  82                 if (err)
  83                         break;  /* really bad sigcontext */
  84         }
  85         return err;
  86 }
  87
  88 static int protected_restore_fp_context(struct sigcontext __user *sc)
  89 {
  90         int err, tmp __maybe_unused;
  91         while (1) {
  92                 lock_fpu_owner();
  93                 own_fpu_inatomic(0);
  94                 err = restore_fp_context(sc); /* this might fail */
  95                 unlock_fpu_owner();
  96                 if (likely(!err))
  97                         break;
  98                 /* touch the sigcontext and try again */
  99                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
 100                         __get_user(tmp, &sc->sc_fpregs[31]) |
 101                         __get_user(tmp, &sc->sc_fpc_csr);
 102                 if (err)
 103                         break;  /* really bad sigcontext */
 104         }
 105         return err;
 106 }
 107
 108 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 109 {
 110         int err = 0;
 111         int i;
 112         unsigned int used_math;
 113
 114         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 115
 116         err |= __put_user(0, &sc->sc_regs[0]);
 117         for (i = 1; i < 32; i++)
 118                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 119
 120 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 121         err |= __put_user(regs->acx, &sc->sc_acx);
 122 #endif
 123         err |= __put_user(regs->hi, &sc->sc_mdhi);
 124         err |= __put_user(regs->lo, &sc->sc_mdlo);
 125         if (cpu_has_dsp) {
 126                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 127                 err |= __put_user(mflo1(), &sc->sc_lo1);
 128                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 129                 err |= __put_user(mflo2(), &sc->sc_lo2);
 130                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 131                 err |= __put_user(mflo3(), &sc->sc_lo3);
 132                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 133         }
 134
 135         used_math = !!used_math();
 136         err |= __put_user(used_math, &sc->sc_used_math);
 137
 138         if (used_math) {
 139                 /*
 140                  * Save FPU state to signal context. Signal handler
 141                  * will "inherit" current FPU state.
 142                  */
 143                 err |= protected_save_fp_context(sc);
 144         }
 145         return err;
 146 }
 147
 148 int fpcsr_pending(unsigned int __user *fpcsr)
 149 {
 150         int err, sig = 0;
 151         unsigned int csr, enabled;
 152
 153         err = __get_user(csr, fpcsr);
 154         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 155         /*
 156          * If the signal handler set some FPU exceptions, clear it and
 157          * send SIGFPE.
 158          */
 159         if (csr & enabled) {
 160                 csr &= ~enabled;
 161                 err |= __put_user(csr, fpcsr);
 162                 sig = SIGFPE;
 163         }
 164         return err ?: sig;
 165 }
 166
 167 static int
 168 check_and_restore_fp_context(struct sigcontext __user *sc)
 169 {
 170         int err, sig;
 171
 172         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 173         if (err > 0)
 174                 err = 0;
 175         err |= protected_restore_fp_context(sc);
 176         return err ?: sig;
 177 }
 178
 179 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 180 {
 181         unsigned int used_math;
 182         unsigned long treg;
 183         int err = 0;
 184         int i;
 185
 186         /* Always make any pending restarted system calls return -EINTR */
 187         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 188
 189         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 190
 191 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 192         err |= __get_user(regs->acx, &sc->sc_acx);
 193 #endif
 194         err |= __get_user(regs->hi, &sc->sc_mdhi);
 195         err |= __get_user(regs->lo, &sc->sc_mdlo);
 196         if (cpu_has_dsp) {
 197                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 198                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 199                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 200                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 201                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 202                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 203                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 204         }
 205
 206         for (i = 1; i < 32; i++)
 207                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 208
 209         err |= __get_user(used_math, &sc->sc_used_math);
 210         conditional_used_math(used_math);
 211
 212         if (used_math) {
 213                 /* restore fpu context if we have used it before */
 214                 if (!err)
 215                         err = check_and_restore_fp_context(sc);
 216         } else {
 217                 /* signal handler may have used FPU.  Give it up. */
 218                 lose_fpu(0);
 219         }
 220
 221         return err;
 222 }
 223
 224 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 225                           size_t frame_size)
 226 {
 227         unsigned long sp;
 228
 229         /* Default to using normal stack */
 230         sp = regs->regs[29];
 231
 232         /*
 233          * FPU emulator may have it's own trampoline active just
 234          * above the user stack, 16-bytes before the next lowest
 235          * 16 byte boundary.  Try to avoid trashing it.
 236          */
 237         sp -= 32;
 238
 239         /* This is the X/Open sanctioned signal stack switching.  */
 240         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 241                 sp = current->sas_ss_sp + current->sas_ss_size;
 242
 243         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 244 }
 245
 246 /*
 247  * Atomically swap in the new signal mask, and wait for a signal.
 248  */
 249
 250 #ifdef CONFIG_TRAD_SIGNALS
 251 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
 252 {
 253         return sys_rt_sigsuspend(uset, sizeof(sigset_t));
 254 }
 255 #endif
 256
 257 #ifdef CONFIG_TRAD_SIGNALS
 258 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 259         struct sigaction __user *, oact)
 260 {
 261         struct k_sigaction new_ka, old_ka;
 262         int ret;
 263         int err = 0;
 264
 265         if (act) {
 266                 old_sigset_t mask;
 267
 268                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 269                         return -EFAULT;
 270                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 271                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 272                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 273                 if (err)
 274                         return -EFAULT;
 275
 276                 siginitset(&new_ka.sa.sa_mask, mask);
 277         }
 278
 279         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 280
 281         if (!ret && oact) {
 282                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 283                         return -EFAULT;
 284                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 285                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 286                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 287                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 288                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 289                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 290                 if (err)
 291                         return -EFAULT;
 292         }
 293
 294         return ret;
 295 }
 296 #endif
 297
 298 #ifdef CONFIG_TRAD_SIGNALS
 299 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 300 {
 301         struct sigframe __user *frame;
 302         sigset_t blocked;
 303         int sig;
 304
 305         frame = (struct sigframe __user *) regs.regs[29];
 306         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 307                 goto badframe;
 308         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 309                 goto badframe;
 310
 311         set_current_blocked(&blocked);
 312
 313         sig = restore_sigcontext(&regs, &frame->sf_sc);
 314         if (sig < 0)
 315                 goto badframe;
 316         else if (sig)
 317                 force_sig(sig, current);
 318
 319         /*
 320          * Don't let your children do this ...
 321          */
 322         __asm__ __volatile__(
 323                 "move\t$29, %0\n\t"
 324                 "j\tsyscall_exit"
 325                 :/* no outputs */
 326                 :"r" (&regs));
 327         /* Unreached */
 328
 329 badframe:
 330         force_sig(SIGSEGV, current);
 331 }
 332 #endif /* CONFIG_TRAD_SIGNALS */
 333
 334 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 335 {
 336         struct rt_sigframe __user *frame;
 337         sigset_t set;
 338         int sig;
 339
 340         frame = (struct rt_sigframe __user *) regs.regs[29];
 341         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 342                 goto badframe;
 343         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 344                 goto badframe;
 345
 346         set_current_blocked(&set);
 347
 348         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 349         if (sig < 0)
 350                 goto badframe;
 351         else if (sig)
 352                 force_sig(sig, current);
 353
 354         if (restore_altstack(&frame->rs_uc.uc_stack))
 355                 goto badframe;
 356
 357         /*
 358          * Don't let your children do this ...
 359          */
 360         __asm__ __volatile__(
 361                 "move\t$29, %0\n\t"
 362                 "j\tsyscall_exit"
 363                 :/* no outputs */
 364                 :"r" (&regs));
 365         /* Unreached */
 366
 367 badframe:
 368         force_sig(SIGSEGV, current);
 369 }
 370
 371 #ifdef CONFIG_TRAD_SIGNALS
 372 static int setup_frame(void *sig_return, struct k_sigaction *ka,
 373                        struct pt_regs *regs, int signr, sigset_t *set)
 374 {
 375         struct sigframe __user *frame;
 376         int err = 0;
 377
 378         frame = get_sigframe(ka, regs, sizeof(*frame));
 379         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 380                 goto give_sigsegv;
 381
 382         err |= setup_sigcontext(regs, &frame->sf_sc);
 383         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 384         if (err)
 385                 goto give_sigsegv;
 386
 387         /*
 388          * Arguments to signal handler:
 389          *
 390          *   a0 = signal number
 391          *   a1 = 0 (should be cause)
 392          *   a2 = pointer to struct sigcontext
 393          *
 394          * $25 and c0_epc point to the signal handler, $29 points to the
 395          * struct sigframe.
 396          */
 397         regs->regs[ 4] = signr;
 398         regs->regs[ 5] = 0;
 399         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 400         regs->regs[29] = (unsigned long) frame;
 401         regs->regs[31] = (unsigned long) sig_return;
 402         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 403
 404         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 405                current->comm, current->pid,
 406                frame, regs->cp0_epc, regs->regs[31]);
 407         return 0;
 408
 409 give_sigsegv:
 410         force_sigsegv(signr, current);
 411         return -EFAULT;
 412 }
 413 #endif
 414
 415 static int setup_rt_frame(void *sig_return, struct k_sigaction *ka,
 416                           struct pt_regs *regs, int signr, sigset_t *set,
 417                           siginfo_t *info)
 418 {
 419         struct rt_sigframe __user *frame;
 420         int err = 0;
 421
 422         frame = get_sigframe(ka, regs, sizeof(*frame));
 423         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 424                 goto give_sigsegv;
 425
 426         /* Create siginfo.  */
 427         err |= copy_siginfo_to_user(&frame->rs_info, info);
 428
 429         /* Create the ucontext.  */
 430         err |= __put_user(0, &frame->rs_uc.uc_flags);
 431         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 432         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 433         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 434         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 435
 436         if (err)
 437                 goto give_sigsegv;
 438
 439         /*
 440          * Arguments to signal handler:
 441          *
 442          *   a0 = signal number
 443          *   a1 = 0 (should be cause)
 444          *   a2 = pointer to ucontext
 445          *
 446          * $25 and c0_epc point to the signal handler, $29 points to
 447          * the struct rt_sigframe.
 448          */
 449         regs->regs[ 4] = signr;
 450         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 451         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 452         regs->regs[29] = (unsigned long) frame;
 453         regs->regs[31] = (unsigned long) sig_return;
 454         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 455
 456         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 457                current->comm, current->pid,
 458                frame, regs->cp0_epc, regs->regs[31]);
 459
 460         return 0;
 461
 462 give_sigsegv:
 463         force_sigsegv(signr, current);
 464         return -EFAULT;
 465 }
 466
 467 struct mips_abi mips_abi = {
 468 #ifdef CONFIG_TRAD_SIGNALS
 469         .setup_frame    = setup_frame,
 470         .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
 471 #endif
 472         .setup_rt_frame = setup_rt_frame,
 473         .rt_signal_return_offset =
 474                 offsetof(struct mips_vdso, rt_signal_trampoline),
 475         .restart        = __NR_restart_syscall
 476 };
 477
 478 static void handle_signal(unsigned long sig, siginfo_t *info,
 479         struct k_sigaction *ka, struct pt_regs *regs)
 480 {
 481         sigset_t *oldset = sigmask_to_save();
 482         int ret;
 483         struct mips_abi *abi = current->thread.abi;
 484 #ifdef CONFIG_CPU_MICROMIPS
 485         void *vdso;
 486         unsigned int tmp = (unsigned int)current->mm->context.vdso;
 487
 488         set_isa16_mode(tmp);
 489         vdso = (void *)tmp;
 490 #else
 491         void *vdso = current->mm->context.vdso;
 492 #endif
 493
 494         if (regs->regs[0]) {
 495                 switch(regs->regs[2]) {
 496                 case ERESTART_RESTARTBLOCK:
 497                 case ERESTARTNOHAND:
 498                         regs->regs[2] = EINTR;
 499                         break;
 500                 case ERESTARTSYS:
 501                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 502                                 regs->regs[2] = EINTR;
 503                                 break;
 504                         }
 505                 /* fallthrough */
 506                 case ERESTARTNOINTR:
 507                         regs->regs[7] = regs->regs[26];
 508                         regs->regs[2] = regs->regs[0];
 509                         regs->cp0_epc -= 4;
 510                 }
 511
 512                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 513         }
 514
 515         if (sig_uses_siginfo(ka))
 516                 ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
 517                                           ka, regs, sig, oldset, info);
 518         else
 519                 ret = abi->setup_frame(vdso + abi->signal_return_offset,
 520                                        ka, regs, sig, oldset);
 521
 522         if (ret)
 523                 return;
 524
 525         signal_delivered(sig, info, ka, regs, 0);
 526 }
 527
 528 static void do_signal(struct pt_regs *regs)
 529 {
 530         struct k_sigaction ka;
 531         siginfo_t info;
 532         int signr;
 533
 534         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 535         if (signr > 0) {
 536                 /* Whee!  Actually deliver the signal.  */
 537                 handle_signal(signr, &info, &ka, regs);
 538                 return;
 539         }
 540
 541         if (regs->regs[0]) {
 542                 switch (regs->regs[2]) {
 543                 case ERESTARTNOHAND:
 544                 case ERESTARTSYS:
 545                 case ERESTARTNOINTR:
 546                         regs->regs[2] = regs->regs[0];
 547                         regs->regs[7] = regs->regs[26];
 548                         regs->cp0_epc -= 4;
 549                         break;
 550
 551                 case ERESTART_RESTARTBLOCK:
 552                         regs->regs[2] = current->thread.abi->restart;
 553                         regs->regs[7] = regs->regs[26];
 554                         regs->cp0_epc -= 4;
 555                         break;
 556                 }
 557                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 558         }
 559
 560         /*
 561          * If there's no signal to deliver, we just put the saved sigmask
 562          * back
 563          */
 564         restore_saved_sigmask();
 565 }
 566
 567 /*
 568  * notification of userspace execution resumption
 569  * - triggered by the TIF_WORK_MASK flags
 570  */
 571 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 572         __u32 thread_info_flags)
 573 {
 574         local_irq_enable();
 575
 576         /* deal with pending signal delivery */
 577         if (thread_info_flags & _TIF_SIGPENDING)
 578                 do_signal(regs);
 579
 580         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 581                 clear_thread_flag(TIF_NOTIFY_RESUME);
 582                 tracehook_notify_resume(regs);
 583         }
 584 }
 585
 586 #ifdef CONFIG_SMP
 587 static int smp_save_fp_context(struct sigcontext __user *sc)
 588 {
 589         return raw_cpu_has_fpu
 590                ? _save_fp_context(sc)
 591                : fpu_emulator_save_context(sc);
 592 }
 593
 594 static int smp_restore_fp_context(struct sigcontext __user *sc)
 595 {
 596         return raw_cpu_has_fpu
 597                ? _restore_fp_context(sc)
 598                : fpu_emulator_restore_context(sc);
 599 }
 600 #endif
 601
 602 static int signal_setup(void)
 603 {
 604 #ifdef CONFIG_SMP
 605         /* For now just do the cpu_has_fpu check when the functions are invoked */
 606         save_fp_context = smp_save_fp_context;
 607         restore_fp_context = smp_restore_fp_context;
 608 #else
 609         if (cpu_has_fpu) {
 610                 save_fp_context = _save_fp_context;
 611                 restore_fp_context = _restore_fp_context;
 612         } else {
 613                 save_fp_context = fpu_emulator_save_context;
 614                 restore_fp_context = fpu_emulator_restore_context;
 615         }
 616 #endif
 617
 618         return 0;
 619 }
 620
 621 arch_initcall(signal_setup);