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/context_tracking.h>
  12 #include <linux/irqflags.h>
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/personality.h>
  16 #include <linux/smp.h>
  17 #include <linux/kernel.h>
  18 #include <linux/signal.h>
  19 #include <linux/errno.h>
  20 #include <linux/wait.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/unistd.h>
  23 #include <linux/compiler.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/tracehook.h>
  27
  28 #include <asm/abi.h>
  29 #include <asm/asm.h>
  30 #include <linux/bitops.h>
  31 #include <asm/cacheflush.h>
  32 #include <asm/fpu.h>
  33 #include <asm/sim.h>
  34 #include <asm/ucontext.h>
  35 #include <asm/cpu-features.h>
  36 #include <asm/war.h>
  37 #include <asm/vdso.h>
  38 #include <asm/dsp.h>
  39 #include <asm/inst.h>
  40
  41 #include "signal-common.h"
  42
  43 static int (*save_fp_context)(struct sigcontext __user *sc);
  44 static int (*restore_fp_context)(struct sigcontext __user *sc);
  45
  46 extern asmlinkage int _save_fp_context(struct sigcontext __user *sc);
  47 extern asmlinkage int _restore_fp_context(struct sigcontext __user *sc);
  48
  49 extern asmlinkage int fpu_emulator_save_context(struct sigcontext __user *sc);
  50 extern asmlinkage int fpu_emulator_restore_context(struct sigcontext __user *sc);
  51
  52 struct sigframe {
  53         u32 sf_ass[4];          /* argument save space for o32 */
  54         u32 sf_pad[2];          /* Was: signal trampoline */
  55         struct sigcontext sf_sc;
  56         sigset_t sf_mask;
  57 };
  58
  59 struct rt_sigframe {
  60         u32 rs_ass[4];          /* argument save space for o32 */
  61         u32 rs_pad[2];          /* Was: signal trampoline */
  62         struct siginfo rs_info;
  63         struct ucontext rs_uc;
  64 };
  65
  66 /*
  67  * Helper routines
  68  */
  69 static int protected_save_fp_context(struct sigcontext __user *sc)
  70 {
  71         int err;
  72         while (1) {
  73                 lock_fpu_owner();
  74                 own_fpu_inatomic(1);
  75                 err = save_fp_context(sc); /* this might fail */
  76                 unlock_fpu_owner();
  77                 if (likely(!err))
  78                         break;
  79                 /* touch the sigcontext and try again */
  80                 err = __put_user(0, &sc->sc_fpregs[0]) |
  81                         __put_user(0, &sc->sc_fpregs[31]) |
  82                         __put_user(0, &sc->sc_fpc_csr);
  83                 if (err)
  84                         break;  /* really bad sigcontext */
  85         }
  86         return err;
  87 }
  88
  89 static int protected_restore_fp_context(struct sigcontext __user *sc)
  90 {
  91         int err, tmp __maybe_unused;
  92         while (1) {
  93                 lock_fpu_owner();
  94                 own_fpu_inatomic(0);
  95                 err = restore_fp_context(sc); /* this might fail */
  96                 unlock_fpu_owner();
  97                 if (likely(!err))
  98                         break;
  99                 /* touch the sigcontext and try again */
 100                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
 101                         __get_user(tmp, &sc->sc_fpregs[31]) |
 102                         __get_user(tmp, &sc->sc_fpc_csr);
 103                 if (err)
 104                         break;  /* really bad sigcontext */
 105         }
 106         return err;
 107 }
 108
 109 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 110 {
 111         int err = 0;
 112         int i;
 113         unsigned int used_math;
 114
 115         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 116
 117         err |= __put_user(0, &sc->sc_regs[0]);
 118         for (i = 1; i < 32; i++)
 119                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 120
 121 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 122         err |= __put_user(regs->acx, &sc->sc_acx);
 123 #endif
 124         err |= __put_user(regs->hi, &sc->sc_mdhi);
 125         err |= __put_user(regs->lo, &sc->sc_mdlo);
 126         if (cpu_has_dsp) {
 127                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 128                 err |= __put_user(mflo1(), &sc->sc_lo1);
 129                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 130                 err |= __put_user(mflo2(), &sc->sc_lo2);
 131                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 132                 err |= __put_user(mflo3(), &sc->sc_lo3);
 133                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 134         }
 135
 136         used_math = !!used_math();
 137         err |= __put_user(used_math, &sc->sc_used_math);
 138
 139         if (used_math) {
 140                 /*
 141                  * Save FPU state to signal context. Signal handler
 142                  * will "inherit" current FPU state.
 143                  */
 144                 err |= protected_save_fp_context(sc);
 145         }
 146         return err;
 147 }
 148
 149 int fpcsr_pending(unsigned int __user *fpcsr)
 150 {
 151         int err, sig = 0;
 152         unsigned int csr, enabled;
 153
 154         err = __get_user(csr, fpcsr);
 155         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 156         /*
 157          * If the signal handler set some FPU exceptions, clear it and
 158          * send SIGFPE.
 159          */
 160         if (csr & enabled) {
 161                 csr &= ~enabled;
 162                 err |= __put_user(csr, fpcsr);
 163                 sig = SIGFPE;
 164         }
 165         return err ?: sig;
 166 }
 167
 168 static int
 169 check_and_restore_fp_context(struct sigcontext __user *sc)
 170 {
 171         int err, sig;
 172
 173         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 174         if (err > 0)
 175                 err = 0;
 176         err |= protected_restore_fp_context(sc);
 177         return err ?: sig;
 178 }
 179
 180 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 181 {
 182         unsigned int used_math;
 183         unsigned long treg;
 184         int err = 0;
 185         int i;
 186
 187         /* Always make any pending restarted system calls return -EINTR */
 188         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 189
 190         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 191
 192 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 193         err |= __get_user(regs->acx, &sc->sc_acx);
 194 #endif
 195         err |= __get_user(regs->hi, &sc->sc_mdhi);
 196         err |= __get_user(regs->lo, &sc->sc_mdlo);
 197         if (cpu_has_dsp) {
 198                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 199                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 200                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 201                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 202                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 203                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 204                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 205         }
 206
 207         for (i = 1; i < 32; i++)
 208                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 209
 210         err |= __get_user(used_math, &sc->sc_used_math);
 211         conditional_used_math(used_math);
 212
 213         if (used_math) {
 214                 /* restore fpu context if we have used it before */
 215                 if (!err)
 216                         err = check_and_restore_fp_context(sc);
 217         } else {
 218                 /* signal handler may have used FPU.  Give it up. */
 219                 lose_fpu(0);
 220         }
 221
 222         return err;
 223 }
 224
 225 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 226                           size_t frame_size)
 227 {
 228         unsigned long sp;
 229
 230         /* Default to using normal stack */
 231         sp = regs->regs[29];
 232
 233         /*
 234          * FPU emulator may have it's own trampoline active just
 235          * above the user stack, 16-bytes before the next lowest
 236          * 16 byte boundary.  Try to avoid trashing it.
 237          */
 238         sp -= 32;
 239
 240         /* This is the X/Open sanctioned signal stack switching.  */
 241         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 242                 sp = current->sas_ss_sp + current->sas_ss_size;
 243
 244         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 245 }
 246
 247 /*
 248  * Atomically swap in the new signal mask, and wait for a signal.
 249  */
 250
 251 #ifdef CONFIG_TRAD_SIGNALS
 252 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
 253 {
 254         return sys_rt_sigsuspend(uset, sizeof(sigset_t));
 255 }
 256 #endif
 257
 258 #ifdef CONFIG_TRAD_SIGNALS
 259 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 260         struct sigaction __user *, oact)
 261 {
 262         struct k_sigaction new_ka, old_ka;
 263         int ret;
 264         int err = 0;
 265
 266         if (act) {
 267                 old_sigset_t mask;
 268
 269                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 270                         return -EFAULT;
 271                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 272                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 273                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 274                 if (err)
 275                         return -EFAULT;
 276
 277                 siginitset(&new_ka.sa.sa_mask, mask);
 278         }
 279
 280         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 281
 282         if (!ret && oact) {
 283                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 284                         return -EFAULT;
 285                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 286                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 287                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 288                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 289                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 290                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 291                 if (err)
 292                         return -EFAULT;
 293         }
 294
 295         return ret;
 296 }
 297 #endif
 298
 299 #ifdef CONFIG_TRAD_SIGNALS
 300 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 301 {
 302         struct sigframe __user *frame;
 303         sigset_t blocked;
 304         int sig;
 305
 306         frame = (struct sigframe __user *) regs.regs[29];
 307         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 308                 goto badframe;
 309         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 310                 goto badframe;
 311
 312         set_current_blocked(&blocked);
 313
 314         sig = restore_sigcontext(&regs, &frame->sf_sc);
 315         if (sig < 0)
 316                 goto badframe;
 317         else if (sig)
 318                 force_sig(sig, current);
 319
 320         /*
 321          * Don't let your children do this ...
 322          */
 323         __asm__ __volatile__(
 324                 "move\t$29, %0\n\t"
 325                 "j\tsyscall_exit"
 326                 :/* no outputs */
 327                 :"r" (&regs));
 328         /* Unreached */
 329
 330 badframe:
 331         force_sig(SIGSEGV, current);
 332 }
 333 #endif /* CONFIG_TRAD_SIGNALS */
 334
 335 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 336 {
 337         struct rt_sigframe __user *frame;
 338         sigset_t set;
 339         int sig;
 340
 341         frame = (struct rt_sigframe __user *) regs.regs[29];
 342         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 343                 goto badframe;
 344         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 345                 goto badframe;
 346
 347         set_current_blocked(&set);
 348
 349         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 350         if (sig < 0)
 351                 goto badframe;
 352         else if (sig)
 353                 force_sig(sig, current);
 354
 355         if (restore_altstack(&frame->rs_uc.uc_stack))
 356                 goto badframe;
 357
 358         /*
 359          * Don't let your children do this ...
 360          */
 361         __asm__ __volatile__(
 362                 "move\t$29, %0\n\t"
 363                 "j\tsyscall_exit"
 364                 :/* no outputs */
 365                 :"r" (&regs));
 366         /* Unreached */
 367
 368 badframe:
 369         force_sig(SIGSEGV, current);
 370 }
 371
 372 #ifdef CONFIG_TRAD_SIGNALS
 373 static int setup_frame(void *sig_return, struct k_sigaction *ka,
 374                        struct pt_regs *regs, int signr, sigset_t *set)
 375 {
 376         struct sigframe __user *frame;
 377         int err = 0;
 378
 379         frame = get_sigframe(ka, regs, sizeof(*frame));
 380         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 381                 goto give_sigsegv;
 382
 383         err |= setup_sigcontext(regs, &frame->sf_sc);
 384         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 385         if (err)
 386                 goto give_sigsegv;
 387
 388         /*
 389          * Arguments to signal handler:
 390          *
 391          *   a0 = signal number
 392          *   a1 = 0 (should be cause)
 393          *   a2 = pointer to struct sigcontext
 394          *
 395          * $25 and c0_epc point to the signal handler, $29 points to the
 396          * struct sigframe.
 397          */
 398         regs->regs[ 4] = signr;
 399         regs->regs[ 5] = 0;
 400         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 401         regs->regs[29] = (unsigned long) frame;
 402         regs->regs[31] = (unsigned long) sig_return;
 403         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 404
 405         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 406                current->comm, current->pid,
 407                frame, regs->cp0_epc, regs->regs[31]);
 408         return 0;
 409
 410 give_sigsegv:
 411         force_sigsegv(signr, current);
 412         return -EFAULT;
 413 }
 414 #endif
 415
 416 static int setup_rt_frame(void *sig_return, struct k_sigaction *ka,
 417                           struct pt_regs *regs, int signr, sigset_t *set,
 418                           siginfo_t *info)
 419 {
 420         struct rt_sigframe __user *frame;
 421         int err = 0;
 422
 423         frame = get_sigframe(ka, regs, sizeof(*frame));
 424         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 425                 goto give_sigsegv;
 426
 427         /* Create siginfo.  */
 428         err |= copy_siginfo_to_user(&frame->rs_info, info);
 429
 430         /* Create the ucontext.  */
 431         err |= __put_user(0, &frame->rs_uc.uc_flags);
 432         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 433         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 434         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 435         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 436
 437         if (err)
 438                 goto give_sigsegv;
 439
 440         /*
 441          * Arguments to signal handler:
 442          *
 443          *   a0 = signal number
 444          *   a1 = 0 (should be cause)
 445          *   a2 = pointer to ucontext
 446          *
 447          * $25 and c0_epc point to the signal handler, $29 points to
 448          * the struct rt_sigframe.
 449          */
 450         regs->regs[ 4] = signr;
 451         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 452         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 453         regs->regs[29] = (unsigned long) frame;
 454         regs->regs[31] = (unsigned long) sig_return;
 455         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 456
 457         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 458                current->comm, current->pid,
 459                frame, regs->cp0_epc, regs->regs[31]);
 460
 461         return 0;
 462
 463 give_sigsegv:
 464         force_sigsegv(signr, current);
 465         return -EFAULT;
 466 }
 467
 468 struct mips_abi mips_abi = {
 469 #ifdef CONFIG_TRAD_SIGNALS
 470         .setup_frame    = setup_frame,
 471         .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
 472 #endif
 473         .setup_rt_frame = setup_rt_frame,
 474         .rt_signal_return_offset =
 475                 offsetof(struct mips_vdso, rt_signal_trampoline),
 476         .restart        = __NR_restart_syscall
 477 };
 478
 479 static void handle_signal(unsigned long sig, siginfo_t *info,
 480         struct k_sigaction *ka, struct pt_regs *regs)
 481 {
 482         sigset_t *oldset = sigmask_to_save();
 483         int ret;
 484         struct mips_abi *abi = current->thread.abi;
 485 #ifdef CONFIG_CPU_MICROMIPS
 486         void *vdso;
 487         unsigned int tmp = (unsigned int)current->mm->context.vdso;
 488
 489         set_isa16_mode(tmp);
 490         vdso = (void *)tmp;
 491 #else
 492         void *vdso = current->mm->context.vdso;
 493 #endif
 494
 495         if (regs->regs[0]) {
 496                 switch(regs->regs[2]) {
 497                 case ERESTART_RESTARTBLOCK:
 498                 case ERESTARTNOHAND:
 499                         regs->regs[2] = EINTR;
 500                         break;
 501                 case ERESTARTSYS:
 502                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 503                                 regs->regs[2] = EINTR;
 504                                 break;
 505                         }
 506                 /* fallthrough */
 507                 case ERESTARTNOINTR:
 508                         regs->regs[7] = regs->regs[26];
 509                         regs->regs[2] = regs->regs[0];
 510                         regs->cp0_epc -= 4;
 511                 }
 512
 513                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 514         }
 515
 516         if (sig_uses_siginfo(ka))
 517                 ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
 518                                           ka, regs, sig, oldset, info);
 519         else
 520                 ret = abi->setup_frame(vdso + abi->signal_return_offset,
 521                                        ka, regs, sig, oldset);
 522
 523         if (ret)
 524                 return;
 525
 526         signal_delivered(sig, info, ka, regs, 0);
 527 }
 528
 529 static void do_signal(struct pt_regs *regs)
 530 {
 531         struct k_sigaction ka;
 532         siginfo_t info;
 533         int signr;
 534
 535         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 536         if (signr > 0) {
 537                 /* Whee!  Actually deliver the signal.  */
 538                 handle_signal(signr, &info, &ka, regs);
 539                 return;
 540         }
 541
 542         if (regs->regs[0]) {
 543                 switch (regs->regs[2]) {
 544                 case ERESTARTNOHAND:
 545                 case ERESTARTSYS:
 546                 case ERESTARTNOINTR:
 547                         regs->regs[2] = regs->regs[0];
 548                         regs->regs[7] = regs->regs[26];
 549                         regs->cp0_epc -= 4;
 550                         break;
 551
 552                 case ERESTART_RESTARTBLOCK:
 553                         regs->regs[2] = current->thread.abi->restart;
 554                         regs->regs[7] = regs->regs[26];
 555                         regs->cp0_epc -= 4;
 556                         break;
 557                 }
 558                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 559         }
 560
 561         /*
 562          * If there's no signal to deliver, we just put the saved sigmask
 563          * back
 564          */
 565         restore_saved_sigmask();
 566 }
 567
 568 /*
 569  * notification of userspace execution resumption
 570  * - triggered by the TIF_WORK_MASK flags
 571  */
 572 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 573         __u32 thread_info_flags)
 574 {
 575         local_irq_enable();
 576
 577         user_exit();
 578
 579         /* deal with pending signal delivery */
 580         if (thread_info_flags & _TIF_SIGPENDING)
 581                 do_signal(regs);
 582
 583         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 584                 clear_thread_flag(TIF_NOTIFY_RESUME);
 585                 tracehook_notify_resume(regs);
 586         }
 587
 588         user_enter();
 589 }
 590
 591 #ifdef CONFIG_SMP
 592 static int smp_save_fp_context(struct sigcontext __user *sc)
 593 {
 594         return raw_cpu_has_fpu
 595                ? _save_fp_context(sc)
 596                : fpu_emulator_save_context(sc);
 597 }
 598
 599 static int smp_restore_fp_context(struct sigcontext __user *sc)
 600 {
 601         return raw_cpu_has_fpu
 602                ? _restore_fp_context(sc)
 603                : fpu_emulator_restore_context(sc);
 604 }
 605 #endif
 606
 607 static int signal_setup(void)
 608 {
 609 #ifdef CONFIG_SMP
 610         /* For now just do the cpu_has_fpu check when the functions are invoked */
 611         save_fp_context = smp_save_fp_context;
 612         restore_fp_context = smp_restore_fp_context;
 613 #else
 614         if (cpu_has_fpu) {
 615                 save_fp_context = _save_fp_context;
 616                 restore_fp_context = _restore_fp_context;
 617         } else {
 618                 save_fp_context = fpu_emulator_save_context;
 619                 restore_fp_context = fpu_emulator_restore_context;
 620         }
 621 #endif
 622
 623         return 0;
 624 }
 625
 626 arch_initcall(signal_setup);