linux/arch/frv/kernel/signal.c
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   1/* signal.c: FRV specific bits of signal handling
   2 *
   3 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 * - Derived from arch/m68k/kernel/signal.c
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; either version
  10 * 2 of the License, or (at your option) any later version.
  11 */
  12
  13#include <linux/sched.h>
  14#include <linux/mm.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/personality.h>
  23#include <linux/freezer.h>
  24#include <asm/ucontext.h>
  25#include <asm/uaccess.h>
  26#include <asm/cacheflush.h>
  27
  28#define DEBUG_SIG 0
  29
  30#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  31
  32struct fdpic_func_descriptor {
  33        unsigned long   text;
  34        unsigned long   GOT;
  35};
  36
  37/*
  38 * Atomically swap in the new signal mask, and wait for a signal.
  39 */
  40asmlinkage int sys_sigsuspend(int history0, int history1, old_sigset_t mask)
  41{
  42        mask &= _BLOCKABLE;
  43        spin_lock_irq(&current->sighand->siglock);
  44        current->saved_sigmask = current->blocked;
  45        siginitset(&current->blocked, mask);
  46        recalc_sigpending();
  47        spin_unlock_irq(&current->sighand->siglock);
  48
  49        current->state = TASK_INTERRUPTIBLE;
  50        schedule();
  51        set_thread_flag(TIF_RESTORE_SIGMASK);
  52        return -ERESTARTNOHAND;
  53}
  54
  55asmlinkage int sys_sigaction(int sig,
  56                             const struct old_sigaction __user *act,
  57                             struct old_sigaction __user *oact)
  58{
  59        struct k_sigaction new_ka, old_ka;
  60        int ret;
  61
  62        if (act) {
  63                old_sigset_t mask;
  64                if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  65                    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  66                    __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  67                        return -EFAULT;
  68                __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  69                __get_user(mask, &act->sa_mask);
  70                siginitset(&new_ka.sa.sa_mask, mask);
  71        }
  72
  73        ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  74
  75        if (!ret && oact) {
  76                if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  77                    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  78                    __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
  79                        return -EFAULT;
  80                __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
  81                __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
  82        }
  83
  84        return ret;
  85}
  86
  87asmlinkage
  88int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  89{
  90        return do_sigaltstack(uss, uoss, __frame->sp);
  91}
  92
  93
  94/*
  95 * Do a signal return; undo the signal stack.
  96 */
  97
  98struct sigframe
  99{
 100        __sigrestore_t pretcode;
 101        int sig;
 102        struct sigcontext sc;
 103        unsigned long extramask[_NSIG_WORDS-1];
 104        uint32_t retcode[2];
 105};
 106
 107struct rt_sigframe
 108{
 109        __sigrestore_t pretcode;
 110        int sig;
 111        struct siginfo __user *pinfo;
 112        void __user *puc;
 113        struct siginfo info;
 114        struct ucontext uc;
 115        uint32_t retcode[2];
 116};
 117
 118static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
 119{
 120        struct user_context *user = current->thread.user;
 121        unsigned long tbr, psr;
 122
 123        tbr = user->i.tbr;
 124        psr = user->i.psr;
 125        if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
 126                goto badframe;
 127        user->i.tbr = tbr;
 128        user->i.psr = psr;
 129
 130        restore_user_regs(user);
 131
 132        user->i.syscallno = -1;         /* disable syscall checks */
 133
 134        *_gr8 = user->i.gr[8];
 135        return 0;
 136
 137 badframe:
 138        return 1;
 139}
 140
 141asmlinkage int sys_sigreturn(void)
 142{
 143        struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
 144        sigset_t set;
 145        int gr8;
 146
 147        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 148                goto badframe;
 149        if (__get_user(set.sig[0], &frame->sc.sc_oldmask))
 150                goto badframe;
 151
 152        if (_NSIG_WORDS > 1 &&
 153            __copy_from_user(&set.sig[1], &frame->extramask, sizeof(frame->extramask)))
 154                goto badframe;
 155
 156        sigdelsetmask(&set, ~_BLOCKABLE);
 157        spin_lock_irq(&current->sighand->siglock);
 158        current->blocked = set;
 159        recalc_sigpending();
 160        spin_unlock_irq(&current->sighand->siglock);
 161
 162        if (restore_sigcontext(&frame->sc, &gr8))
 163                goto badframe;
 164        return gr8;
 165
 166 badframe:
 167        force_sig(SIGSEGV, current);
 168        return 0;
 169}
 170
 171asmlinkage int sys_rt_sigreturn(void)
 172{
 173        struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
 174        sigset_t set;
 175        int gr8;
 176
 177        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 178                goto badframe;
 179        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 180                goto badframe;
 181
 182        sigdelsetmask(&set, ~_BLOCKABLE);
 183        spin_lock_irq(&current->sighand->siglock);
 184        current->blocked = set;
 185        recalc_sigpending();
 186        spin_unlock_irq(&current->sighand->siglock);
 187
 188        if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
 189                goto badframe;
 190
 191        if (do_sigaltstack(&frame->uc.uc_stack, NULL, __frame->sp) == -EFAULT)
 192                goto badframe;
 193
 194        return gr8;
 195
 196badframe:
 197        force_sig(SIGSEGV, current);
 198        return 0;
 199}
 200
 201/*
 202 * Set up a signal frame
 203 */
 204static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
 205{
 206        save_user_regs(current->thread.user);
 207
 208        if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
 209                goto badframe;
 210
 211        /* non-iBCS2 extensions.. */
 212        if (__put_user(mask, &sc->sc_oldmask) < 0)
 213                goto badframe;
 214
 215        return 0;
 216
 217 badframe:
 218        return 1;
 219}
 220
 221/*****************************************************************************/
 222/*
 223 * Determine which stack to use..
 224 */
 225static inline void __user *get_sigframe(struct k_sigaction *ka,
 226                                        size_t frame_size)
 227{
 228        unsigned long sp;
 229
 230        /* Default to using normal stack */
 231        sp = __frame->sp;
 232
 233        /* This is the X/Open sanctioned signal stack switching.  */
 234        if (ka->sa.sa_flags & SA_ONSTACK) {
 235                if (! sas_ss_flags(sp))
 236                        sp = current->sas_ss_sp + current->sas_ss_size;
 237        }
 238
 239        return (void __user *) ((sp - frame_size) & ~7UL);
 240
 241} /* end get_sigframe() */
 242
 243/*****************************************************************************/
 244/*
 245 *
 246 */
 247static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 248{
 249        struct sigframe __user *frame;
 250        int rsig;
 251
 252        frame = get_sigframe(ka, sizeof(*frame));
 253
 254        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 255                goto give_sigsegv;
 256
 257        rsig = sig;
 258        if (sig < 32 &&
 259            __current_thread_info->exec_domain &&
 260            __current_thread_info->exec_domain->signal_invmap)
 261                rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 262
 263        if (__put_user(rsig, &frame->sig) < 0)
 264                goto give_sigsegv;
 265
 266        if (setup_sigcontext(&frame->sc, set->sig[0]))
 267                goto give_sigsegv;
 268
 269        if (_NSIG_WORDS > 1) {
 270                if (__copy_to_user(frame->extramask, &set->sig[1],
 271                                   sizeof(frame->extramask)))
 272                        goto give_sigsegv;
 273        }
 274
 275        /* Set up to return from userspace.  If provided, use a stub
 276         * already in userspace.  */
 277        if (ka->sa.sa_flags & SA_RESTORER) {
 278                if (__put_user(ka->sa.sa_restorer, &frame->pretcode) < 0)
 279                        goto give_sigsegv;
 280        }
 281        else {
 282                /* Set up the following code on the stack:
 283                 *      setlos  #__NR_sigreturn,gr7
 284                 *      tira    gr0,0
 285                 */
 286                if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 287                    __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
 288                    __put_user(0xc0700000, &frame->retcode[1]))
 289                        goto give_sigsegv;
 290
 291                flush_icache_range((unsigned long) frame->retcode,
 292                                   (unsigned long) (frame->retcode + 2));
 293        }
 294
 295        /* set up registers for signal handler */
 296        __frame->sp   = (unsigned long) frame;
 297        __frame->lr   = (unsigned long) &frame->retcode;
 298        __frame->gr8  = sig;
 299
 300        if (current->personality & FDPIC_FUNCPTRS) {
 301                struct fdpic_func_descriptor __user *funcptr =
 302                        (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 303                __get_user(__frame->pc, &funcptr->text);
 304                __get_user(__frame->gr15, &funcptr->GOT);
 305        } else {
 306                __frame->pc   = (unsigned long) ka->sa.sa_handler;
 307                __frame->gr15 = 0;
 308        }
 309
 310        set_fs(USER_DS);
 311
 312        /* the tracer may want to single-step inside the handler */
 313        if (test_thread_flag(TIF_SINGLESTEP))
 314                ptrace_notify(SIGTRAP);
 315
 316#if DEBUG_SIG
 317        printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 318               sig, current->comm, current->pid, frame, __frame->pc,
 319               frame->pretcode);
 320#endif
 321
 322        return 0;
 323
 324give_sigsegv:
 325        force_sig(SIGSEGV, current);
 326        return -EFAULT;
 327
 328} /* end setup_frame() */
 329
 330/*****************************************************************************/
 331/*
 332 *
 333 */
 334static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 335                          sigset_t *set)
 336{
 337        struct rt_sigframe __user *frame;
 338        int rsig;
 339
 340        frame = get_sigframe(ka, sizeof(*frame));
 341
 342        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 343                goto give_sigsegv;
 344
 345        rsig = sig;
 346        if (sig < 32 &&
 347            __current_thread_info->exec_domain &&
 348            __current_thread_info->exec_domain->signal_invmap)
 349                rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 350
 351        if (__put_user(rsig,            &frame->sig) ||
 352            __put_user(&frame->info,    &frame->pinfo) ||
 353            __put_user(&frame->uc,      &frame->puc))
 354                goto give_sigsegv;
 355
 356        if (copy_siginfo_to_user(&frame->info, info))
 357                goto give_sigsegv;
 358
 359        /* Create the ucontext.  */
 360        if (__put_user(0, &frame->uc.uc_flags) ||
 361            __put_user(NULL, &frame->uc.uc_link) ||
 362            __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp) ||
 363            __put_user(sas_ss_flags(__frame->sp), &frame->uc.uc_stack.ss_flags) ||
 364            __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size))
 365                goto give_sigsegv;
 366
 367        if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
 368                goto give_sigsegv;
 369
 370        if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
 371                goto give_sigsegv;
 372
 373        /* Set up to return from userspace.  If provided, use a stub
 374         * already in userspace.  */
 375        if (ka->sa.sa_flags & SA_RESTORER) {
 376                if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
 377                        goto give_sigsegv;
 378        }
 379        else {
 380                /* Set up the following code on the stack:
 381                 *      setlos  #__NR_sigreturn,gr7
 382                 *      tira    gr0,0
 383                 */
 384                if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 385                    __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
 386                    __put_user(0xc0700000, &frame->retcode[1]))
 387                        goto give_sigsegv;
 388
 389                flush_icache_range((unsigned long) frame->retcode,
 390                                   (unsigned long) (frame->retcode + 2));
 391        }
 392
 393        /* Set up registers for signal handler */
 394        __frame->sp  = (unsigned long) frame;
 395        __frame->lr   = (unsigned long) &frame->retcode;
 396        __frame->gr8 = sig;
 397        __frame->gr9 = (unsigned long) &frame->info;
 398
 399        if (current->personality & FDPIC_FUNCPTRS) {
 400                struct fdpic_func_descriptor __user *funcptr =
 401                        (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 402                __get_user(__frame->pc, &funcptr->text);
 403                __get_user(__frame->gr15, &funcptr->GOT);
 404        } else {
 405                __frame->pc   = (unsigned long) ka->sa.sa_handler;
 406                __frame->gr15 = 0;
 407        }
 408
 409        set_fs(USER_DS);
 410
 411        /* the tracer may want to single-step inside the handler */
 412        if (test_thread_flag(TIF_SINGLESTEP))
 413                ptrace_notify(SIGTRAP);
 414
 415#if DEBUG_SIG
 416        printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 417               sig, current->comm, current->pid, frame, __frame->pc,
 418               frame->pretcode);
 419#endif
 420
 421        return 0;
 422
 423give_sigsegv:
 424        force_sig(SIGSEGV, current);
 425        return -EFAULT;
 426
 427} /* end setup_rt_frame() */
 428
 429/*****************************************************************************/
 430/*
 431 * OK, we're invoking a handler
 432 */
 433static int handle_signal(unsigned long sig, siginfo_t *info,
 434                         struct k_sigaction *ka, sigset_t *oldset)
 435{
 436        int ret;
 437
 438        /* Are we from a system call? */
 439        if (in_syscall(__frame)) {
 440                /* If so, check system call restarting.. */
 441                switch (__frame->gr8) {
 442                case -ERESTART_RESTARTBLOCK:
 443                case -ERESTARTNOHAND:
 444                        __frame->gr8 = -EINTR;
 445                        break;
 446
 447                case -ERESTARTSYS:
 448                        if (!(ka->sa.sa_flags & SA_RESTART)) {
 449                                __frame->gr8 = -EINTR;
 450                                break;
 451                        }
 452
 453                        /* fallthrough */
 454                case -ERESTARTNOINTR:
 455                        __frame->gr8 = __frame->orig_gr8;
 456                        __frame->pc -= 4;
 457                }
 458        }
 459
 460        /* Set up the stack frame */
 461        if (ka->sa.sa_flags & SA_SIGINFO)
 462                ret = setup_rt_frame(sig, ka, info, oldset);
 463        else
 464                ret = setup_frame(sig, ka, oldset);
 465
 466        if (ret == 0) {
 467                spin_lock_irq(&current->sighand->siglock);
 468                sigorsets(&current->blocked, &current->blocked,
 469                          &ka->sa.sa_mask);
 470                if (!(ka->sa.sa_flags & SA_NODEFER))
 471                        sigaddset(&current->blocked, sig);
 472                recalc_sigpending();
 473                spin_unlock_irq(&current->sighand->siglock);
 474        }
 475
 476        return ret;
 477
 478} /* end handle_signal() */
 479
 480/*****************************************************************************/
 481/*
 482 * Note that 'init' is a special process: it doesn't get signals it doesn't
 483 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 484 * mistake.
 485 */
 486static void do_signal(void)
 487{
 488        struct k_sigaction ka;
 489        siginfo_t info;
 490        sigset_t *oldset;
 491        int signr;
 492
 493        /*
 494         * We want the common case to go fast, which
 495         * is why we may in certain cases get here from
 496         * kernel mode. Just return without doing anything
 497         * if so.
 498         */
 499        if (!user_mode(__frame))
 500                return;
 501
 502        if (try_to_freeze())
 503                goto no_signal;
 504
 505        if (test_thread_flag(TIF_RESTORE_SIGMASK))
 506                oldset = &current->saved_sigmask;
 507        else
 508                oldset = &current->blocked;
 509
 510        signr = get_signal_to_deliver(&info, &ka, __frame, NULL);
 511        if (signr > 0) {
 512                if (handle_signal(signr, &info, &ka, oldset) == 0) {
 513                        /* a signal was successfully delivered; the saved
 514                         * sigmask will have been stored in the signal frame,
 515                         * and will be restored by sigreturn, so we can simply
 516                         * clear the TIF_RESTORE_SIGMASK flag */
 517                        if (test_thread_flag(TIF_RESTORE_SIGMASK))
 518                                clear_thread_flag(TIF_RESTORE_SIGMASK);
 519                }
 520
 521                return;
 522        }
 523
 524no_signal:
 525        /* Did we come from a system call? */
 526        if (__frame->syscallno >= 0) {
 527                /* Restart the system call - no handlers present */
 528                switch (__frame->gr8) {
 529                case -ERESTARTNOHAND:
 530                case -ERESTARTSYS:
 531                case -ERESTARTNOINTR:
 532                        __frame->gr8 = __frame->orig_gr8;
 533                        __frame->pc -= 4;
 534                        break;
 535
 536                case -ERESTART_RESTARTBLOCK:
 537                        __frame->gr8 = __NR_restart_syscall;
 538                        __frame->pc -= 4;
 539                        break;
 540                }
 541        }
 542
 543        /* if there's no signal to deliver, we just put the saved sigmask
 544         * back */
 545        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 546                clear_thread_flag(TIF_RESTORE_SIGMASK);
 547                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 548        }
 549
 550} /* end do_signal() */
 551
 552/*****************************************************************************/
 553/*
 554 * notification of userspace execution resumption
 555 * - triggered by the TIF_WORK_MASK flags
 556 */
 557asmlinkage void do_notify_resume(__u32 thread_info_flags)
 558{
 559        /* pending single-step? */
 560        if (thread_info_flags & _TIF_SINGLESTEP)
 561                clear_thread_flag(TIF_SINGLESTEP);
 562
 563        /* deal with pending signal delivery */
 564        if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
 565                do_signal();
 566
 567} /* end do_notify_resume() */
 568