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 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *,unewset, size_t, sigsetsize)
 263 {
 264         sigset_t newset;
 265
 266         /* XXX Don't preclude handling different sized sigset_t's.  */
 267         if (sigsetsize != sizeof(sigset_t))
 268                 return -EINVAL;
 269
 270         if (copy_from_user(&newset, unewset, sizeof(newset)))
 271                 return -EFAULT;
 272         return sigsuspend(&newset);
 273 }
 274
 275 #ifdef CONFIG_TRAD_SIGNALS
 276 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 277         struct sigaction __user *, oact)
 278 {
 279         struct k_sigaction new_ka, old_ka;
 280         int ret;
 281         int err = 0;
 282
 283         if (act) {
 284                 old_sigset_t mask;
 285
 286                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 287                         return -EFAULT;
 288                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 289                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 290                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 291                 if (err)
 292                         return -EFAULT;
 293
 294                 siginitset(&new_ka.sa.sa_mask, mask);
 295         }
 296
 297         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 298
 299         if (!ret && oact) {
 300                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 301                         return -EFAULT;
 302                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 303                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 304                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 305                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 306                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 307                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 308                 if (err)
 309                         return -EFAULT;
 310         }
 311
 312         return ret;
 313 }
 314 #endif
 315
 316 #ifdef CONFIG_TRAD_SIGNALS
 317 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 318 {
 319         struct sigframe __user *frame;
 320         sigset_t blocked;
 321         int sig;
 322
 323         frame = (struct sigframe __user *) regs.regs[29];
 324         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 325                 goto badframe;
 326         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 327                 goto badframe;
 328
 329         set_current_blocked(&blocked);
 330
 331         sig = restore_sigcontext(&regs, &frame->sf_sc);
 332         if (sig < 0)
 333                 goto badframe;
 334         else if (sig)
 335                 force_sig(sig, current);
 336
 337         /*
 338          * Don't let your children do this ...
 339          */
 340         __asm__ __volatile__(
 341                 "move\t$29, %0\n\t"
 342                 "j\tsyscall_exit"
 343                 :/* no outputs */
 344                 :"r" (&regs));
 345         /* Unreached */
 346
 347 badframe:
 348         force_sig(SIGSEGV, current);
 349 }
 350 #endif /* CONFIG_TRAD_SIGNALS */
 351
 352 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 353 {
 354         struct rt_sigframe __user *frame;
 355         sigset_t set;
 356         int sig;
 357
 358         frame = (struct rt_sigframe __user *) regs.regs[29];
 359         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 360                 goto badframe;
 361         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 362                 goto badframe;
 363
 364         set_current_blocked(&set);
 365
 366         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 367         if (sig < 0)
 368                 goto badframe;
 369         else if (sig)
 370                 force_sig(sig, current);
 371
 372         if (restore_altstack(&frame->rs_uc.uc_stack))
 373                 goto badframe;
 374
 375         /*
 376          * Don't let your children do this ...
 377          */
 378         __asm__ __volatile__(
 379                 "move\t$29, %0\n\t"
 380                 "j\tsyscall_exit"
 381                 :/* no outputs */
 382                 :"r" (&regs));
 383         /* Unreached */
 384
 385 badframe:
 386         force_sig(SIGSEGV, current);
 387 }
 388
 389 #ifdef CONFIG_TRAD_SIGNALS
 390 static int setup_frame(void *sig_return, struct k_sigaction *ka,
 391                        struct pt_regs *regs, int signr, sigset_t *set)
 392 {
 393         struct sigframe __user *frame;
 394         int err = 0;
 395
 396         frame = get_sigframe(ka, regs, sizeof(*frame));
 397         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 398                 goto give_sigsegv;
 399
 400         err |= setup_sigcontext(regs, &frame->sf_sc);
 401         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 402         if (err)
 403                 goto give_sigsegv;
 404
 405         /*
 406          * Arguments to signal handler:
 407          *
 408          *   a0 = signal number
 409          *   a1 = 0 (should be cause)
 410          *   a2 = pointer to struct sigcontext
 411          *
 412          * $25 and c0_epc point to the signal handler, $29 points to the
 413          * struct sigframe.
 414          */
 415         regs->regs[ 4] = signr;
 416         regs->regs[ 5] = 0;
 417         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 418         regs->regs[29] = (unsigned long) frame;
 419         regs->regs[31] = (unsigned long) sig_return;
 420         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 421
 422         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 423                current->comm, current->pid,
 424                frame, regs->cp0_epc, regs->regs[31]);
 425         return 0;
 426
 427 give_sigsegv:
 428         force_sigsegv(signr, current);
 429         return -EFAULT;
 430 }
 431 #endif
 432
 433 static int setup_rt_frame(void *sig_return, struct k_sigaction *ka,
 434                           struct pt_regs *regs, int signr, sigset_t *set,
 435                           siginfo_t *info)
 436 {
 437         struct rt_sigframe __user *frame;
 438         int err = 0;
 439
 440         frame = get_sigframe(ka, regs, sizeof(*frame));
 441         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 442                 goto give_sigsegv;
 443
 444         /* Create siginfo.  */
 445         err |= copy_siginfo_to_user(&frame->rs_info, info);
 446
 447         /* Create the ucontext.  */
 448         err |= __put_user(0, &frame->rs_uc.uc_flags);
 449         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 450         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 451         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 452         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 453
 454         if (err)
 455                 goto give_sigsegv;
 456
 457         /*
 458          * Arguments to signal handler:
 459          *
 460          *   a0 = signal number
 461          *   a1 = 0 (should be cause)
 462          *   a2 = pointer to ucontext
 463          *
 464          * $25 and c0_epc point to the signal handler, $29 points to
 465          * the struct rt_sigframe.
 466          */
 467         regs->regs[ 4] = signr;
 468         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 469         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 470         regs->regs[29] = (unsigned long) frame;
 471         regs->regs[31] = (unsigned long) sig_return;
 472         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 473
 474         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 475                current->comm, current->pid,
 476                frame, regs->cp0_epc, regs->regs[31]);
 477
 478         return 0;
 479
 480 give_sigsegv:
 481         force_sigsegv(signr, current);
 482         return -EFAULT;
 483 }
 484
 485 struct mips_abi mips_abi = {
 486 #ifdef CONFIG_TRAD_SIGNALS
 487         .setup_frame    = setup_frame,
 488         .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
 489 #endif
 490         .setup_rt_frame = setup_rt_frame,
 491         .rt_signal_return_offset =
 492                 offsetof(struct mips_vdso, rt_signal_trampoline),
 493         .restart        = __NR_restart_syscall
 494 };
 495
 496 static void handle_signal(unsigned long sig, siginfo_t *info,
 497         struct k_sigaction *ka, struct pt_regs *regs)
 498 {
 499         sigset_t *oldset = sigmask_to_save();
 500         int ret;
 501         struct mips_abi *abi = current->thread.abi;
 502         void *vdso = current->mm->context.vdso;
 503
 504         if (regs->regs[0]) {
 505                 switch(regs->regs[2]) {
 506                 case ERESTART_RESTARTBLOCK:
 507                 case ERESTARTNOHAND:
 508                         regs->regs[2] = EINTR;
 509                         break;
 510                 case ERESTARTSYS:
 511                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 512                                 regs->regs[2] = EINTR;
 513                                 break;
 514                         }
 515                 /* fallthrough */
 516                 case ERESTARTNOINTR:
 517                         regs->regs[7] = regs->regs[26];
 518                         regs->regs[2] = regs->regs[0];
 519                         regs->cp0_epc -= 4;
 520                 }
 521
 522                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 523         }
 524
 525         if (sig_uses_siginfo(ka))
 526                 ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
 527                                           ka, regs, sig, oldset, info);
 528         else
 529                 ret = abi->setup_frame(vdso + abi->signal_return_offset,
 530                                        ka, regs, sig, oldset);
 531
 532         if (ret)
 533                 return;
 534
 535         signal_delivered(sig, info, ka, regs, 0);
 536 }
 537
 538 static void do_signal(struct pt_regs *regs)
 539 {
 540         struct k_sigaction ka;
 541         siginfo_t info;
 542         int signr;
 543
 544         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 545         if (signr > 0) {
 546                 /* Whee!  Actually deliver the signal.  */
 547                 handle_signal(signr, &info, &ka, regs);
 548                 return;
 549         }
 550
 551         if (regs->regs[0]) {
 552                 switch (regs->regs[2]) {
 553                 case ERESTARTNOHAND:
 554                 case ERESTARTSYS:
 555                 case ERESTARTNOINTR:
 556                         regs->regs[2] = regs->regs[0];
 557                         regs->regs[7] = regs->regs[26];
 558                         regs->cp0_epc -= 4;
 559                         break;
 560
 561                 case ERESTART_RESTARTBLOCK:
 562                         regs->regs[2] = current->thread.abi->restart;
 563                         regs->regs[7] = regs->regs[26];
 564                         regs->cp0_epc -= 4;
 565                         break;
 566                 }
 567                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 568         }
 569
 570         /*
 571          * If there's no signal to deliver, we just put the saved sigmask
 572          * back
 573          */
 574         restore_saved_sigmask();
 575 }
 576
 577 /*
 578  * notification of userspace execution resumption
 579  * - triggered by the TIF_WORK_MASK flags
 580  */
 581 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 582         __u32 thread_info_flags)
 583 {
 584         local_irq_enable();
 585
 586         /* deal with pending signal delivery */
 587         if (thread_info_flags & _TIF_SIGPENDING)
 588                 do_signal(regs);
 589
 590         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 591                 clear_thread_flag(TIF_NOTIFY_RESUME);
 592                 tracehook_notify_resume(regs);
 593         }
 594 }
 595
 596 #ifdef CONFIG_SMP
 597 static int smp_save_fp_context(struct sigcontext __user *sc)
 598 {
 599         return raw_cpu_has_fpu
 600                ? _save_fp_context(sc)
 601                : fpu_emulator_save_context(sc);
 602 }
 603
 604 static int smp_restore_fp_context(struct sigcontext __user *sc)
 605 {
 606         return raw_cpu_has_fpu
 607                ? _restore_fp_context(sc)
 608                : fpu_emulator_restore_context(sc);
 609 }
 610 #endif
 611
 612 static int signal_setup(void)
 613 {
 614 #ifdef CONFIG_SMP
 615         /* For now just do the cpu_has_fpu check when the functions are invoked */
 616         save_fp_context = smp_save_fp_context;
 617         restore_fp_context = smp_restore_fp_context;
 618 #else
 619         if (cpu_has_fpu) {
 620                 save_fp_context = _save_fp_context;
 621                 restore_fp_context = _restore_fp_context;
 622         } else {
 623                 save_fp_context = fpu_emulator_save_context;
 624                 restore_fp_context = fpu_emulator_restore_context;
 625         }
 626 #endif
 627
 628         return 0;
 629 }
 630
 631 arch_initcall(signal_setup);