linux/arch/cris/arch-v32/kernel/signal.c
<<
>>
Prefs
   1/*
   2 * Copyright (C) 2003, Axis Communications AB.
   3 */
   4
   5#include <linux/sched.h>
   6#include <linux/mm.h>
   7#include <linux/slab.h>
   8#include <linux/kernel.h>
   9#include <linux/signal.h>
  10#include <linux/errno.h>
  11#include <linux/wait.h>
  12#include <linux/ptrace.h>
  13#include <linux/unistd.h>
  14#include <linux/stddef.h>
  15#include <linux/syscalls.h>
  16#include <linux/vmalloc.h>
  17
  18#include <asm/io.h>
  19#include <asm/processor.h>
  20#include <asm/ucontext.h>
  21#include <asm/uaccess.h>
  22#include <arch/ptrace.h>
  23#include <arch/hwregs/cpu_vect.h>
  24
  25extern unsigned long cris_signal_return_page;
  26
  27/*
  28 * A syscall in CRIS is really a "break 13" instruction, which is 2
  29 * bytes. The registers is manipulated so upon return the instruction
  30 * will be executed again.
  31 *
  32 * This relies on that PC points to the instruction after the break call.
  33 */
  34#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;
  35
  36/* Signal frames. */
  37struct signal_frame {
  38        struct sigcontext sc;
  39        unsigned long extramask[_NSIG_WORDS - 1];
  40        unsigned char retcode[8];       /* Trampoline code. */
  41};
  42
  43struct rt_signal_frame {
  44        struct siginfo *pinfo;
  45        void *puc;
  46        struct siginfo info;
  47        struct ucontext uc;
  48        unsigned char retcode[8];       /* Trampoline code. */
  49};
  50
  51void do_signal(int restart, struct pt_regs *regs);
  52void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
  53                      struct pt_regs *regs);
  54/*
  55 * Swap in the new signal mask, and wait for a signal. Define some
  56 * dummy arguments to be able to reach the regs argument.
  57 */
  58int
  59sys_sigsuspend(old_sigset_t mask)
  60{
  61        sigset_t blocked;
  62        siginitset(&blocked, mask);
  63        return sigsuspend(&blocked);
  64}
  65
  66int
  67sys_sigaction(int signal, const struct old_sigaction *act,
  68              struct old_sigaction *oact)
  69{
  70        int retval;
  71        struct k_sigaction newk;
  72        struct k_sigaction oldk;
  73
  74        if (act) {
  75                old_sigset_t mask;
  76
  77                if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  78                    __get_user(newk.sa.sa_handler, &act->sa_handler) ||
  79                    __get_user(newk.sa.sa_restorer, &act->sa_restorer) ||
  80                    __get_user(newk.sa.sa_flags, &act->sa_flags) ||
  81                    __get_user(mask, &act->sa_mask))
  82                        return -EFAULT;
  83
  84                siginitset(&newk.sa.sa_mask, mask);
  85        }
  86
  87        retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);
  88
  89        if (!retval && oact) {
  90                if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  91                    __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
  92                    __put_user(oldk.sa.sa_restorer, &oact->sa_restorer) ||
  93                    __put_user(oldk.sa.sa_flags, &oact->sa_flags) ||
  94                    __put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask))
  95                        return -EFAULT;
  96
  97        }
  98
  99        return retval;
 100}
 101
 102int
 103sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 104{
 105        return do_sigaltstack(uss, uoss, rdusp());
 106}
 107
 108static int
 109restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 110{
 111        unsigned int err = 0;
 112        unsigned long old_usp;
 113
 114        /* Always make any pending restarted system calls return -EINTR */
 115        current_thread_info()->restart_block.fn = do_no_restart_syscall;
 116
 117        /*
 118         * Restore the registers from &sc->regs. sc is already checked
 119         * for VERIFY_READ since the signal_frame was previously
 120         * checked in sys_sigreturn().
 121         */
 122        if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
 123                goto badframe;
 124
 125        /* Make that the user-mode flag is set. */
 126        regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));
 127
 128        /* Restore the old USP. */
 129        err |= __get_user(old_usp, &sc->usp);
 130        wrusp(old_usp);
 131
 132        return err;
 133
 134badframe:
 135        return 1;
 136}
 137
 138/* Define some dummy arguments to be able to reach the regs argument. */
 139asmlinkage int
 140sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
 141              struct pt_regs *regs)
 142{
 143        sigset_t set;
 144        struct signal_frame __user *frame;
 145        unsigned long oldspc = regs->spc;
 146        unsigned long oldccs = regs->ccs;
 147
 148        frame = (struct signal_frame *) rdusp();
 149
 150        /*
 151         * Since the signal is stacked on a dword boundary, the frame
 152         * should be dword aligned here as well. It it's not, then the
 153         * user is trying some funny business.
 154         */
 155        if (((long)frame) & 3)
 156                goto badframe;
 157
 158        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 159                goto badframe;
 160
 161        if (__get_user(set.sig[0], &frame->sc.oldmask) ||
 162            (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
 163                                                 frame->extramask,
 164                                                 sizeof(frame->extramask))))
 165                goto badframe;
 166
 167        set_current_blocked(&set);
 168
 169        if (restore_sigcontext(regs, &frame->sc))
 170                goto badframe;
 171
 172        keep_debug_flags(oldccs, oldspc, regs);
 173
 174        return regs->r10;
 175
 176badframe:
 177        force_sig(SIGSEGV, current);
 178        return 0;
 179}
 180
 181/* Define some dummy variables to be able to reach the regs argument. */
 182asmlinkage int
 183sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
 184                 struct pt_regs *regs)
 185{
 186        sigset_t set;
 187        struct rt_signal_frame __user *frame;
 188        unsigned long oldspc = regs->spc;
 189        unsigned long oldccs = regs->ccs;
 190
 191        frame = (struct rt_signal_frame *) rdusp();
 192
 193        /*
 194         * Since the signal is stacked on a dword boundary, the frame
 195         * should be dword aligned here as well. It it's not, then the
 196         * user is trying some funny business.
 197         */
 198        if (((long)frame) & 3)
 199                goto badframe;
 200
 201        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 202                goto badframe;
 203
 204        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 205                goto badframe;
 206
 207        set_current_blocked(&set);
 208
 209        if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 210                goto badframe;
 211
 212        if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT)
 213                goto badframe;
 214
 215        keep_debug_flags(oldccs, oldspc, regs);
 216
 217        return regs->r10;
 218
 219badframe:
 220        force_sig(SIGSEGV, current);
 221        return 0;
 222}
 223
 224/* Setup a signal frame. */
 225static int
 226setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 227                 unsigned long mask)
 228{
 229        int err;
 230        unsigned long usp;
 231
 232        err = 0;
 233        usp = rdusp();
 234
 235        /*
 236         * Copy the registers. They are located first in sc, so it's
 237         * possible to use sc directly.
 238         */
 239        err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
 240
 241        err |= __put_user(mask, &sc->oldmask);
 242        err |= __put_user(usp, &sc->usp);
 243
 244        return err;
 245}
 246
 247/* Figure out where to put the new signal frame - usually on the stack. */
 248static inline void __user *
 249get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 250{
 251        unsigned long sp;
 252
 253        sp = rdusp();
 254
 255        /* This is the X/Open sanctioned signal stack switching. */
 256        if (ka->sa.sa_flags & SA_ONSTACK) {
 257                if (!on_sig_stack(sp))
 258                        sp = current->sas_ss_sp + current->sas_ss_size;
 259        }
 260
 261        /* Make sure the frame is dword-aligned. */
 262        sp &= ~3;
 263
 264        return (void __user *)(sp - frame_size);
 265}
 266
 267/* Grab and setup a signal frame.
 268 *
 269 * Basically a lot of state-info is stacked, and arranged for the
 270 * user-mode program to return to the kernel using either a trampiline
 271 * which performs the syscall sigreturn(), or a provided user-mode
 272 * trampoline.
 273  */
 274static int
 275setup_frame(int sig, struct k_sigaction *ka,  sigset_t *set,
 276            struct pt_regs * regs)
 277{
 278        int err;
 279        unsigned long return_ip;
 280        struct signal_frame __user *frame;
 281
 282        err = 0;
 283        frame = get_sigframe(ka, regs, sizeof(*frame));
 284
 285        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 286                goto give_sigsegv;
 287
 288        err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
 289
 290        if (err)
 291                goto give_sigsegv;
 292
 293        if (_NSIG_WORDS > 1) {
 294                err |= __copy_to_user(frame->extramask, &set->sig[1],
 295                                      sizeof(frame->extramask));
 296        }
 297
 298        if (err)
 299                goto give_sigsegv;
 300
 301        /*
 302         * Set up to return from user-space. If provided, use a stub
 303         * already located in user-space.
 304         */
 305        if (ka->sa.sa_flags & SA_RESTORER) {
 306                return_ip = (unsigned long)ka->sa.sa_restorer;
 307        } else {
 308                /* Trampoline - the desired return ip is in the signal return page. */
 309                return_ip = cris_signal_return_page;
 310
 311                /*
 312                 * This is movu.w __NR_sigreturn, r9; break 13;
 313                 *
 314                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 315                 * reasons and because gdb uses it as a signature to notice
 316                 * signal handler stack frames.
 317                 */
 318                err |= __put_user(0x9c5f,         (short __user*)(frame->retcode+0));
 319                err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
 320                err |= __put_user(0xe93d,         (short __user*)(frame->retcode+4));
 321        }
 322
 323        if (err)
 324                goto give_sigsegv;
 325
 326        /*
 327         * Set up registers for signal handler.
 328         *
 329         * Where the code enters now.
 330         * Where the code enter later.
 331         * First argument, signo.
 332         */
 333        regs->erp = (unsigned long) ka->sa.sa_handler;
 334        regs->srp = return_ip;
 335        regs->r10 = sig;
 336
 337        /* Actually move the USP to reflect the stacked frame. */
 338        wrusp((unsigned long)frame);
 339
 340        return 0;
 341
 342give_sigsegv:
 343        force_sigsegv(sig, current);
 344        return -EFAULT;
 345}
 346
 347static int
 348setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 349               sigset_t *set, struct pt_regs * regs)
 350{
 351        int err;
 352        unsigned long return_ip;
 353        struct rt_signal_frame __user *frame;
 354
 355        err = 0;
 356        frame = get_sigframe(ka, regs, sizeof(*frame));
 357
 358        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 359                goto give_sigsegv;
 360
 361        /* TODO: what is the current->exec_domain stuff and invmap ? */
 362
 363        err |= __put_user(&frame->info, &frame->pinfo);
 364        err |= __put_user(&frame->uc, &frame->puc);
 365        err |= copy_siginfo_to_user(&frame->info, info);
 366
 367        if (err)
 368                goto give_sigsegv;
 369
 370        /* Clear all the bits of the ucontext we don't use.  */
 371        err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 372        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 373        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 374
 375        if (err)
 376                goto give_sigsegv;
 377
 378        /*
 379         * Set up to return from user-space. If provided, use a stub
 380         * already located in user-space.
 381         */
 382        if (ka->sa.sa_flags & SA_RESTORER) {
 383                return_ip = (unsigned long) ka->sa.sa_restorer;
 384        } else {
 385                /* Trampoline - the desired return ip is in the signal return page. */
 386                return_ip = cris_signal_return_page + 6;
 387
 388                /*
 389                 * This is movu.w __NR_rt_sigreturn, r9; break 13;
 390                 *
 391                 * WE DO NOT USE IT ANY MORE! It's only left here for historical
 392                 * reasons and because gdb uses it as a signature to notice
 393                 * signal handler stack frames.
 394                 */
 395                err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
 396
 397                err |= __put_user(__NR_rt_sigreturn,
 398                                  (short __user*)(frame->retcode+2));
 399
 400                err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
 401        }
 402
 403        if (err)
 404                goto give_sigsegv;
 405
 406        /*
 407         * Set up registers for signal handler.
 408         *
 409         * Where the code enters now.
 410         * Where the code enters later.
 411         * First argument is signo.
 412         * Second argument is (siginfo_t *).
 413         * Third argument is unused.
 414         */
 415        regs->erp = (unsigned long) ka->sa.sa_handler;
 416        regs->srp = return_ip;
 417        regs->r10 = sig;
 418        regs->r11 = (unsigned long) &frame->info;
 419        regs->r12 = 0;
 420
 421        /* Actually move the usp to reflect the stacked frame. */
 422        wrusp((unsigned long)frame);
 423
 424        return 0;
 425
 426give_sigsegv:
 427        force_sigsegv(sig, current);
 428        return -EFAULT;
 429}
 430
 431/* Invoke a signal handler to, well, handle the signal. */
 432static inline void
 433handle_signal(int canrestart, unsigned long sig,
 434              siginfo_t *info, struct k_sigaction *ka,
 435              struct pt_regs * regs)
 436{
 437        sigset_t *oldset = sigmask_to_save();
 438        int ret;
 439
 440        /* Check if this got called from a system call. */
 441        if (canrestart) {
 442                /* If so, check system call restarting. */
 443                switch (regs->r10) {
 444                        case -ERESTART_RESTARTBLOCK:
 445                        case -ERESTARTNOHAND:
 446                                /*
 447                                 * This means that the syscall should
 448                                 * only be restarted if there was no
 449                                 * handler for the signal, and since
 450                                 * this point isn't reached unless
 451                                 * there is a handler, there's no need
 452                                 * to restart.
 453                                 */
 454                                regs->r10 = -EINTR;
 455                                break;
 456
 457                        case -ERESTARTSYS:
 458                                /*
 459                                 * This means restart the syscall if
 460                                 * there is no handler, or the handler
 461                                 * was registered with SA_RESTART.
 462                                 */
 463                                if (!(ka->sa.sa_flags & SA_RESTART)) {
 464                                        regs->r10 = -EINTR;
 465                                        break;
 466                                }
 467
 468                                /* Fall through. */
 469
 470                        case -ERESTARTNOINTR:
 471                                /*
 472                                 * This means that the syscall should
 473                                 * be called again after the signal
 474                                 * handler returns.
 475                                 */
 476                                RESTART_CRIS_SYS(regs);
 477                                break;
 478                }
 479        }
 480
 481        /* Set up the stack frame. */
 482        if (ka->sa.sa_flags & SA_SIGINFO)
 483                ret = setup_rt_frame(sig, ka, info, oldset, regs);
 484        else
 485                ret = setup_frame(sig, ka, oldset, regs);
 486
 487        if (ret == 0)
 488                signal_delivered(sig, info, ka, regs, 0);
 489}
 490
 491/*
 492 * Note that 'init' is a special process: it doesn't get signals it doesn't
 493 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 494 * mistake.
 495 *
 496 * Also note that the regs structure given here as an argument, is the latest
 497 * pushed pt_regs. It may or may not be the same as the first pushed registers
 498 * when the initial usermode->kernelmode transition took place. Therefore
 499 * we can use user_mode(regs) to see if we came directly from kernel or user
 500 * mode below.
 501 */
 502void
 503do_signal(int canrestart, struct pt_regs *regs)
 504{
 505        int signr;
 506        siginfo_t info;
 507        struct k_sigaction ka;
 508
 509        /*
 510         * The common case should go fast, which is why this point is
 511         * reached from kernel-mode. If that's the case, just return
 512         * without doing anything.
 513         */
 514        if (!user_mode(regs))
 515                return;
 516
 517        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 518
 519        if (signr > 0) {
 520                /* Whee!  Actually deliver the signal.  */
 521                handle_signal(canrestart, signr, &info, &ka, regs);
 522                return;
 523        }
 524
 525        /* Got here from a system call? */
 526        if (canrestart) {
 527                /* Restart the system call - no handlers present. */
 528                if (regs->r10 == -ERESTARTNOHAND ||
 529                    regs->r10 == -ERESTARTSYS ||
 530                    regs->r10 == -ERESTARTNOINTR) {
 531                        RESTART_CRIS_SYS(regs);
 532                }
 533
 534                if (regs->r10 == -ERESTART_RESTARTBLOCK){
 535                        regs->r9 = __NR_restart_syscall;
 536                        regs->erp -= 2;
 537                }
 538        }
 539
 540        /* if there's no signal to deliver, we just put the saved sigmask
 541         * back */
 542        restore_saved_sigmask();
 543}
 544
 545asmlinkage void
 546ugdb_trap_user(struct thread_info *ti, int sig)
 547{
 548        if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
 549                /* Zero single-step PC if the reason we stopped wasn't a single
 550                   step exception. This is to avoid relying on it when it isn't
 551                   reliable. */
 552                user_regs(ti)->spc = 0;
 553        }
 554        /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
 555           not within any configured h/w breakpoint range). Synchronize with
 556           what already exists for kernel debugging.  */
 557        if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
 558                /* Break 8: subtract 2 from ERP unless in a delay slot. */
 559                if (!(user_regs(ti)->erp & 0x1))
 560                        user_regs(ti)->erp -= 2;
 561        }
 562        sys_kill(ti->task->pid, sig);
 563}
 564
 565void
 566keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
 567                 struct pt_regs *regs)
 568{
 569        if (oldccs & (1 << Q_CCS_BITNR)) {
 570                /* Pending single step due to single-stepping the break 13
 571                   in the signal trampoline: keep the Q flag. */
 572                regs->ccs |= (1 << Q_CCS_BITNR);
 573                /* S flag should be set - complain if it's not. */
 574                if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
 575                        printk("Q flag but no S flag?");
 576                }
 577                regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 578                /* Assume the SPC is valid and interesting. */
 579                regs->spc = oldspc;
 580
 581        } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
 582                /* If a h/w bp was set in the signal handler we need
 583                   to keep the S flag. */
 584                regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 585                /* Don't keep the old SPC though; if we got here due to
 586                   a single-step, the Q flag should have been set. */
 587        } else if (regs->spc) {
 588                /* If we were single-stepping *before* the signal was taken,
 589                   we don't want to restore that state now, because GDB will
 590                   have forgotten all about it. */
 591                regs->spc = 0;
 592                regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
 593        }
 594}
 595
 596/* Set up the trampolines on the signal return page. */
 597int __init
 598cris_init_signal(void)
 599{
 600        u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 601
 602        /* This is movu.w __NR_sigreturn, r9; break 13; */
 603        data[0] = 0x9c5f;
 604        data[1] = __NR_sigreturn;
 605        data[2] = 0xe93d;
 606        /* This is movu.w __NR_rt_sigreturn, r9; break 13; */
 607        data[3] = 0x9c5f;
 608        data[4] = __NR_rt_sigreturn;
 609        data[5] = 0xe93d;
 610
 611        /* Map to userspace with appropriate permissions (no write access...) */
 612        cris_signal_return_page = (unsigned long)
 613          __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);
 614
 615        return 0;
 616}
 617
 618__initcall(cris_init_signal);
 619