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                 err = own_fpu_inatomic(1);
  75                 if (!err)
  76                         err = save_fp_context(sc); /* this might fail */
  77                 unlock_fpu_owner();
  78                 if (likely(!err))
  79                         break;
  80                 /* touch the sigcontext and try again */
  81                 err = __put_user(0, &sc->sc_fpregs[0]) |
  82                         __put_user(0, &sc->sc_fpregs[31]) |
  83                         __put_user(0, &sc->sc_fpc_csr);
  84                 if (err)
  85                         break;  /* really bad sigcontext */
  86         }
  87         return err;
  88 }
  89
  90 static int protected_restore_fp_context(struct sigcontext __user *sc)
  91 {
  92         int err, tmp __maybe_unused;
  93         while (1) {
  94                 lock_fpu_owner();
  95                 err = own_fpu_inatomic(0);
  96                 if (!err)
  97                         err = restore_fp_context(sc); /* this might fail */
  98                 unlock_fpu_owner();
  99                 if (likely(!err))
 100                         break;
 101                 /* touch the sigcontext and try again */
 102                 err = __get_user(tmp, &sc->sc_fpregs[0]) |
 103                         __get_user(tmp, &sc->sc_fpregs[31]) |
 104                         __get_user(tmp, &sc->sc_fpc_csr);
 105                 if (err)
 106                         break;  /* really bad sigcontext */
 107         }
 108         return err;
 109 }
 110
 111 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 112 {
 113         int err = 0;
 114         int i;
 115         unsigned int used_math;
 116
 117         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 118
 119         err |= __put_user(0, &sc->sc_regs[0]);
 120         for (i = 1; i < 32; i++)
 121                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 122
 123 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 124         err |= __put_user(regs->acx, &sc->sc_acx);
 125 #endif
 126         err |= __put_user(regs->hi, &sc->sc_mdhi);
 127         err |= __put_user(regs->lo, &sc->sc_mdlo);
 128         if (cpu_has_dsp) {
 129                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 130                 err |= __put_user(mflo1(), &sc->sc_lo1);
 131                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 132                 err |= __put_user(mflo2(), &sc->sc_lo2);
 133                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 134                 err |= __put_user(mflo3(), &sc->sc_lo3);
 135                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 136         }
 137
 138         used_math = !!used_math();
 139         err |= __put_user(used_math, &sc->sc_used_math);
 140
 141         if (used_math) {
 142                 /*
 143                  * Save FPU state to signal context. Signal handler
 144                  * will "inherit" current FPU state.
 145                  */
 146                 err |= protected_save_fp_context(sc);
 147         }
 148         return err;
 149 }
 150
 151 int fpcsr_pending(unsigned int __user *fpcsr)
 152 {
 153         int err, sig = 0;
 154         unsigned int csr, enabled;
 155
 156         err = __get_user(csr, fpcsr);
 157         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 158         /*
 159          * If the signal handler set some FPU exceptions, clear it and
 160          * send SIGFPE.
 161          */
 162         if (csr & enabled) {
 163                 csr &= ~enabled;
 164                 err |= __put_user(csr, fpcsr);
 165                 sig = SIGFPE;
 166         }
 167         return err ?: sig;
 168 }
 169
 170 static int
 171 check_and_restore_fp_context(struct sigcontext __user *sc)
 172 {
 173         int err, sig;
 174
 175         err = sig = fpcsr_pending(&sc->sc_fpc_csr);
 176         if (err > 0)
 177                 err = 0;
 178         err |= protected_restore_fp_context(sc);
 179         return err ?: sig;
 180 }
 181
 182 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 183 {
 184         unsigned int used_math;
 185         unsigned long treg;
 186         int err = 0;
 187         int i;
 188
 189         /* Always make any pending restarted system calls return -EINTR */
 190         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 191
 192         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 193
 194 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 195         err |= __get_user(regs->acx, &sc->sc_acx);
 196 #endif
 197         err |= __get_user(regs->hi, &sc->sc_mdhi);
 198         err |= __get_user(regs->lo, &sc->sc_mdlo);
 199         if (cpu_has_dsp) {
 200                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 201                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 202                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 203                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 204                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 205                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 206                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 207         }
 208
 209         for (i = 1; i < 32; i++)
 210                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 211
 212         err |= __get_user(used_math, &sc->sc_used_math);
 213         conditional_used_math(used_math);
 214
 215         if (used_math) {
 216                 /* restore fpu context if we have used it before */
 217                 if (!err)
 218                         err = check_and_restore_fp_context(sc);
 219         } else {
 220                 /* signal handler may have used FPU.  Give it up. */
 221                 lose_fpu(0);
 222         }
 223
 224         return err;
 225 }
 226
 227 void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 228                           size_t frame_size)
 229 {
 230         unsigned long sp;
 231
 232         /* Default to using normal stack */
 233         sp = regs->regs[29];
 234
 235         /*
 236          * FPU emulator may have it's own trampoline active just
 237          * above the user stack, 16-bytes before the next lowest
 238          * 16 byte boundary.  Try to avoid trashing it.
 239          */
 240         sp -= 32;
 241
 242         /* This is the X/Open sanctioned signal stack switching.  */
 243         if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
 244                 sp = current->sas_ss_sp + current->sas_ss_size;
 245
 246         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 247 }
 248
 249 /*
 250  * Atomically swap in the new signal mask, and wait for a signal.
 251  */
 252
 253 #ifdef CONFIG_TRAD_SIGNALS
 254 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
 255 {
 256         return sys_rt_sigsuspend(uset, sizeof(sigset_t));
 257 }
 258 #endif
 259
 260 #ifdef CONFIG_TRAD_SIGNALS
 261 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 262         struct sigaction __user *, oact)
 263 {
 264         struct k_sigaction new_ka, old_ka;
 265         int ret;
 266         int err = 0;
 267
 268         if (act) {
 269                 old_sigset_t mask;
 270
 271                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 272                         return -EFAULT;
 273                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 274                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 275                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 276                 if (err)
 277                         return -EFAULT;
 278
 279                 siginitset(&new_ka.sa.sa_mask, mask);
 280         }
 281
 282         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 283
 284         if (!ret && oact) {
 285                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 286                         return -EFAULT;
 287                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 288                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 289                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 290                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 291                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 292                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 293                 if (err)
 294                         return -EFAULT;
 295         }
 296
 297         return ret;
 298 }
 299 #endif
 300
 301 #ifdef CONFIG_TRAD_SIGNALS
 302 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 303 {
 304         struct sigframe __user *frame;
 305         sigset_t blocked;
 306         int sig;
 307
 308         frame = (struct sigframe __user *) regs.regs[29];
 309         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 310                 goto badframe;
 311         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 312                 goto badframe;
 313
 314         set_current_blocked(&blocked);
 315
 316         sig = restore_sigcontext(&regs, &frame->sf_sc);
 317         if (sig < 0)
 318                 goto badframe;
 319         else if (sig)
 320                 force_sig(sig, current);
 321
 322         /*
 323          * Don't let your children do this ...
 324          */
 325         __asm__ __volatile__(
 326                 "move\t$29, %0\n\t"
 327                 "j\tsyscall_exit"
 328                 :/* no outputs */
 329                 :"r" (&regs));
 330         /* Unreached */
 331
 332 badframe:
 333         force_sig(SIGSEGV, current);
 334 }
 335 #endif /* CONFIG_TRAD_SIGNALS */
 336
 337 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 338 {
 339         struct rt_sigframe __user *frame;
 340         sigset_t set;
 341         int sig;
 342
 343         frame = (struct rt_sigframe __user *) regs.regs[29];
 344         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 345                 goto badframe;
 346         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 347                 goto badframe;
 348
 349         set_current_blocked(&set);
 350
 351         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 352         if (sig < 0)
 353                 goto badframe;
 354         else if (sig)
 355                 force_sig(sig, current);
 356
 357         if (restore_altstack(&frame->rs_uc.uc_stack))
 358                 goto badframe;
 359
 360         /*
 361          * Don't let your children do this ...
 362          */
 363         __asm__ __volatile__(
 364                 "move\t$29, %0\n\t"
 365                 "j\tsyscall_exit"
 366                 :/* no outputs */
 367                 :"r" (&regs));
 368         /* Unreached */
 369
 370 badframe:
 371         force_sig(SIGSEGV, current);
 372 }
 373
 374 #ifdef CONFIG_TRAD_SIGNALS
 375 static int setup_frame(void *sig_return, struct k_sigaction *ka,
 376                        struct pt_regs *regs, int signr, sigset_t *set)
 377 {
 378         struct sigframe __user *frame;
 379         int err = 0;
 380
 381         frame = get_sigframe(ka, regs, sizeof(*frame));
 382         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 383                 goto give_sigsegv;
 384
 385         err |= setup_sigcontext(regs, &frame->sf_sc);
 386         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 387         if (err)
 388                 goto give_sigsegv;
 389
 390         /*
 391          * Arguments to signal handler:
 392          *
 393          *   a0 = signal number
 394          *   a1 = 0 (should be cause)
 395          *   a2 = pointer to struct sigcontext
 396          *
 397          * $25 and c0_epc point to the signal handler, $29 points to the
 398          * struct sigframe.
 399          */
 400         regs->regs[ 4] = signr;
 401         regs->regs[ 5] = 0;
 402         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 403         regs->regs[29] = (unsigned long) frame;
 404         regs->regs[31] = (unsigned long) sig_return;
 405         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 406
 407         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 408                current->comm, current->pid,
 409                frame, regs->cp0_epc, regs->regs[31]);
 410         return 0;
 411
 412 give_sigsegv:
 413         force_sigsegv(signr, current);
 414         return -EFAULT;
 415 }
 416 #endif
 417
 418 static int setup_rt_frame(void *sig_return, struct k_sigaction *ka,
 419                           struct pt_regs *regs, int signr, sigset_t *set,
 420                           siginfo_t *info)
 421 {
 422         struct rt_sigframe __user *frame;
 423         int err = 0;
 424
 425         frame = get_sigframe(ka, regs, sizeof(*frame));
 426         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 427                 goto give_sigsegv;
 428
 429         /* Create siginfo.  */
 430         err |= copy_siginfo_to_user(&frame->rs_info, info);
 431
 432         /* Create the ucontext.  */
 433         err |= __put_user(0, &frame->rs_uc.uc_flags);
 434         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 435         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 436         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 437         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 438
 439         if (err)
 440                 goto give_sigsegv;
 441
 442         /*
 443          * Arguments to signal handler:
 444          *
 445          *   a0 = signal number
 446          *   a1 = 0 (should be cause)
 447          *   a2 = pointer to ucontext
 448          *
 449          * $25 and c0_epc point to the signal handler, $29 points to
 450          * the struct rt_sigframe.
 451          */
 452         regs->regs[ 4] = signr;
 453         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 454         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 455         regs->regs[29] = (unsigned long) frame;
 456         regs->regs[31] = (unsigned long) sig_return;
 457         regs->cp0_epc = regs->regs[25] = (unsigned long) ka->sa.sa_handler;
 458
 459         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 460                current->comm, current->pid,
 461                frame, regs->cp0_epc, regs->regs[31]);
 462
 463         return 0;
 464
 465 give_sigsegv:
 466         force_sigsegv(signr, current);
 467         return -EFAULT;
 468 }
 469
 470 struct mips_abi mips_abi = {
 471 #ifdef CONFIG_TRAD_SIGNALS
 472         .setup_frame    = setup_frame,
 473         .signal_return_offset = offsetof(struct mips_vdso, signal_trampoline),
 474 #endif
 475         .setup_rt_frame = setup_rt_frame,
 476         .rt_signal_return_offset =
 477                 offsetof(struct mips_vdso, rt_signal_trampoline),
 478         .restart        = __NR_restart_syscall
 479 };
 480
 481 static void handle_signal(unsigned long sig, siginfo_t *info,
 482         struct k_sigaction *ka, struct pt_regs *regs)
 483 {
 484         sigset_t *oldset = sigmask_to_save();
 485         int ret;
 486         struct mips_abi *abi = current->thread.abi;
 487 #ifdef CONFIG_CPU_MICROMIPS
 488         void *vdso;
 489         unsigned int tmp = (unsigned int)current->mm->context.vdso;
 490
 491         set_isa16_mode(tmp);
 492         vdso = (void *)tmp;
 493 #else
 494         void *vdso = current->mm->context.vdso;
 495 #endif
 496
 497         if (regs->regs[0]) {
 498                 switch(regs->regs[2]) {
 499                 case ERESTART_RESTARTBLOCK:
 500                 case ERESTARTNOHAND:
 501                         regs->regs[2] = EINTR;
 502                         break;
 503                 case ERESTARTSYS:
 504                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 505                                 regs->regs[2] = EINTR;
 506                                 break;
 507                         }
 508                 /* fallthrough */
 509                 case ERESTARTNOINTR:
 510                         regs->regs[7] = regs->regs[26];
 511                         regs->regs[2] = regs->regs[0];
 512                         regs->cp0_epc -= 4;
 513                 }
 514
 515                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 516         }
 517
 518         if (sig_uses_siginfo(ka))
 519                 ret = abi->setup_rt_frame(vdso + abi->rt_signal_return_offset,
 520                                           ka, regs, sig, oldset, info);
 521         else
 522                 ret = abi->setup_frame(vdso + abi->signal_return_offset,
 523                                        ka, regs, sig, oldset);
 524
 525         if (ret)
 526                 return;
 527
 528         signal_delivered(sig, info, ka, regs, 0);
 529 }
 530
 531 static void do_signal(struct pt_regs *regs)
 532 {
 533         struct k_sigaction ka;
 534         siginfo_t info;
 535         int signr;
 536
 537         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 538         if (signr > 0) {
 539                 /* Whee!  Actually deliver the signal.  */
 540                 handle_signal(signr, &info, &ka, regs);
 541                 return;
 542         }
 543
 544         if (regs->regs[0]) {
 545                 switch (regs->regs[2]) {
 546                 case ERESTARTNOHAND:
 547                 case ERESTARTSYS:
 548                 case ERESTARTNOINTR:
 549                         regs->regs[2] = regs->regs[0];
 550                         regs->regs[7] = regs->regs[26];
 551                         regs->cp0_epc -= 4;
 552                         break;
 553
 554                 case ERESTART_RESTARTBLOCK:
 555                         regs->regs[2] = current->thread.abi->restart;
 556                         regs->regs[7] = regs->regs[26];
 557                         regs->cp0_epc -= 4;
 558                         break;
 559                 }
 560                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 561         }
 562
 563         /*
 564          * If there's no signal to deliver, we just put the saved sigmask
 565          * back
 566          */
 567         restore_saved_sigmask();
 568 }
 569
 570 /*
 571  * notification of userspace execution resumption
 572  * - triggered by the TIF_WORK_MASK flags
 573  */
 574 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 575         __u32 thread_info_flags)
 576 {
 577         local_irq_enable();
 578
 579         user_exit();
 580
 581         /* deal with pending signal delivery */
 582         if (thread_info_flags & _TIF_SIGPENDING)
 583                 do_signal(regs);
 584
 585         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 586                 clear_thread_flag(TIF_NOTIFY_RESUME);
 587                 tracehook_notify_resume(regs);
 588         }
 589
 590         user_enter();
 591 }
 592
 593 #ifdef CONFIG_SMP
 594 static int smp_save_fp_context(struct sigcontext __user *sc)
 595 {
 596         return raw_cpu_has_fpu
 597                ? _save_fp_context(sc)
 598                : fpu_emulator_save_context(sc);
 599 }
 600
 601 static int smp_restore_fp_context(struct sigcontext __user *sc)
 602 {
 603         return raw_cpu_has_fpu
 604                ? _restore_fp_context(sc)
 605                : fpu_emulator_restore_context(sc);
 606 }
 607 #endif
 608
 609 static int signal_setup(void)
 610 {
 611 #ifdef CONFIG_SMP
 612         /* For now just do the cpu_has_fpu check when the functions are invoked */
 613         save_fp_context = smp_save_fp_context;
 614         restore_fp_context = smp_restore_fp_context;
 615 #else
 616         if (cpu_has_fpu) {
 617                 save_fp_context = _save_fp_context;
 618                 restore_fp_context = _restore_fp_context;
 619         } else {
 620                 save_fp_context = fpu_emulator_save_context;
 621                 restore_fp_context = fpu_emulator_restore_context;
 622         }
 623 #endif
 624
 625         return 0;
 626 }
 627
 628 arch_initcall(signal_setup);