Annotation of MiNT/src/signal.c, revision 1.1.1.2

1.1       root        1: /*
                      2: 
                      3: Copyright 1990,1991,1992 Eric R. Smith. All rights reserved.
                      4: 
                      5: */
                      6: 
                      7: 
                      8: 
                      9: /* signal.c:: signal handling routines */
                     10: 
                     11: 
                     12: 
                     13: #include "mint.h"
                     14: 
                     15: 
                     16: 
                     17: void (*sig_routine)(); /* used in intr.s */
                     18: 
1.1.1.2 ! root       19: short sig_exc;         /* used in intr.s */
        !            20: 
1.1       root       21: 
                     22: 
                     23: /*
                     24: 
                     25:  * killgroup(pgrp, sig): send a signal to all members of a process group
                     26: 
                     27:  * returns 0 on success, or an error code on failure
                     28: 
                     29:  */
                     30: 
                     31: 
                     32: 
                     33: long
                     34: 
                     35: killgroup(pgrp, sig)
                     36: 
                     37:        int pgrp, sig;
                     38: 
                     39: {
                     40: 
                     41:        PROC *p;
                     42: 
                     43:        int found = 0;
                     44: 
                     45: 
                     46: 
1.1.1.2 ! root       47:        TRACE(("killgroup %d %d", pgrp, sig));
1.1       root       48: 
                     49: 
                     50: 
                     51:        if (pgrp < 0)
                     52: 
                     53:                return EINTRN;
                     54: 
                     55: 
                     56: 
                     57:        for (p = proclist; p; p = p->gl_next) {
                     58: 
                     59:                if (p->pgrp == pgrp) {
                     60: 
                     61:                        post_sig(p, sig);
                     62: 
                     63:                        found++;
                     64: 
                     65:                }
                     66: 
                     67:        }
                     68: 
                     69:        if (found) {
                     70: 
                     71:                check_sigs();   /* see if the current process is affected */
                     72: 
                     73:                return 0;
                     74: 
                     75:        }
                     76: 
                     77:        else {
                     78: 
1.1.1.2 ! root       79:                DEBUG(("killgroup: no processes found"));
1.1       root       80: 
                     81:                return EFILNF;
                     82: 
                     83:        }
                     84: 
                     85: }
                     86: 
                     87: 
                     88: 
                     89: /* post_sig: post a signal as being pending. It is assumed that the
                     90: 
                     91:    caller has already verified that "sig" is a valid signal, and
                     92: 
                     93:    moreover it is the caller's responsibility to call check_sigs()
                     94: 
                     95:    if it's possible that p == curproc
                     96: 
                     97:  */
                     98: 
                     99: 
                    100: 
                    101: void
                    102: 
                    103: post_sig(p, sig)
                    104: 
                    105:        PROC *p;
                    106: 
                    107:        int sig;
                    108: 
                    109: {
                    110: 
                    111:        ulong sigm;
                    112: 
                    113: 
                    114: 
                    115: /* if process is ignoring this signal, do nothing
                    116: 
                    117:  * also: signal 0 is SIGNULL, and should never be delivered through
                    118: 
                    119:  * the normal channels (indeed, it's filtered out in dossig.c,
                    120: 
                    121:  * but the extra sanity check here is harmless). The kernel uses
                    122: 
                    123:  * signal 0 internally for some purposes, but it is handled
                    124: 
                    125:  * specially (see supexec() in xbios.c, for example).
                    126: 
                    127:  */
                    128: 
                    129:        if (p->sighandle[sig] == SIG_IGN || sig == 0)
                    130: 
                    131:                return;
                    132: 
                    133: 
                    134: 
                    135: /* if the process is already dead, do nothing */
                    136: 
                    137:        if (p->wait_q == ZOMBIE_Q || p->wait_q == TSR_Q)
                    138: 
                    139:                return;
                    140: 
                    141: 
                    142: 
                    143: /* mark the signal as pending */
                    144: 
                    145:        sigm = (1L << (unsigned long)sig);
                    146: 
                    147:        p->sigpending |= sigm;
                    148: 
                    149: 
                    150: 
                    151: /* if the signal is masked, do nothing further */
                    152: 
                    153:        if ( (p->sigmask & sigm) != 0 )
                    154: 
                    155:                return;
                    156: 
                    157: 
                    158: 
                    159: /* otherwise, make sure the process is awake */
                    160: 
                    161:        if (p->wait_q && p->wait_q != READY_Q) {
                    162: 
                    163:                rm_q(p->wait_q, p);
                    164: 
                    165:                add_q(READY_Q, p);
                    166: 
                    167:        }
                    168: 
                    169: }
                    170: 
                    171: 
                    172: 
                    173: /*
                    174: 
                    175:  * check_sigs: see if we have any signals pending. if so,
                    176: 
                    177:  * handle them.
                    178: 
                    179:  */
                    180: 
                    181: 
                    182: 
                    183: void
                    184: 
                    185: check_sigs()
                    186: 
                    187: {
                    188: 
                    189:        ulong sigs, sigm;
                    190: 
1.1.1.2 ! root      191:        int i;
        !           192: 
        !           193:        short deliversig;
1.1       root      194: 
                    195: 
                    196: 
                    197:        if (curproc->pid == 0) return;
                    198: 
1.1.1.2 ! root      199: top:
        !           200: 
1.1       root      201:        sigs = curproc->sigpending & ~(curproc->sigmask);
                    202: 
                    203:        if (sigs) {
                    204: 
                    205:                sigm = 2;
                    206: 
1.1.1.2 ! root      207: /* with tracing we need a mechanism to allow a signal to be delivered
        !           208: 
        !           209:  * to the child (curproc); Fcntl(...TRACEGO...) passes a SIGNULL to indicate that we
        !           210: 
        !           211:  * should really deliver the signal, hence its always safe to remove it
        !           212: 
        !           213:  * from pending.
        !           214: 
        !           215:  */
        !           216: 
        !           217:                deliversig = (curproc->sigpending & 1L);
        !           218: 
        !           219:                curproc->sigpending &= ~1L;
        !           220: 
        !           221: 
        !           222: 
1.1       root      223:                for (i = 1; i < NSIG; i++) {
                    224: 
                    225:                        if (sigs & sigm) {
                    226: 
1.1.1.2 ! root      227:                                curproc->sigpending &= ~sigm;
        !           228: 
        !           229:                                if (curproc->ptracer && !deliversig) {
1.1       root      230: 
1.1.1.2 ! root      231:                                        TRACE(("tracer being notified of signal %d", i));
1.1       root      232: 
1.1.1.2 ! root      233:                                        stop(i);
1.1       root      234: 
1.1.1.2 ! root      235:                /* the parent may reset our pending signals, so check again */
        !           236: 
        !           237:                                        goto top;
        !           238: 
        !           239:                                } else {
        !           240: 
        !           241:                                        ulong omask;
1.1       root      242: 
                    243: 
                    244: 
1.1.1.2 ! root      245:                                        curproc->sigpending &= ~sigm;
1.1       root      246: 
1.1.1.2 ! root      247:                                        omask = curproc->sigmask;
        !           248: 
        !           249: 
        !           250: 
        !           251:                /* sigextra gives which extra signals should also be masked */
        !           252: 
        !           253:                                        curproc->sigmask |= curproc->sigextra[i] | sigm;
        !           254: 
        !           255:                                        handle_sig(i);
1.1       root      256: 
                    257: 
                    258: 
                    259: 
                    260: 
                    261: /*
                    262: 
                    263:  * POSIX.1-3.3.4.2(723) "If and when the user's signal handler returns
                    264: 
                    265:  * normally, the original signal mask is restored."
                    266: 
                    267:  *
                    268: 
                    269:  * BUG?: This unmasking could unmask a pending signal which we will not
                    270: 
                    271:  * see this time around (if the signal number is less than i) and which
                    272: 
                    273:  * was not pending when we started; should we detect this condition and
                    274: 
                    275:  * loop around for a second try? POSIX only guarantees delivery of
                    276: 
                    277:  * one signal per kernel entry, so this shouldn't really be a problem.
                    278: 
                    279:  */
                    280: 
1.1.1.2 ! root      281:                                        curproc->sigmask = omask;       /* unmask signals */
        !           282: 
        !           283:                                }
1.1       root      284: 
                    285:                        }
                    286: 
                    287:                        sigm = sigm << 1;
                    288: 
                    289:                }
                    290: 
                    291:        }
                    292: 
                    293: }
                    294: 
                    295: 
                    296: 
                    297: /*
                    298: 
                    299:  * raise: cause a signal to be raised in the current process
                    300: 
                    301:  */
                    302: 
                    303: 
                    304: 
                    305: void
                    306: 
                    307: raise(sig)
                    308: 
                    309:        int sig;
                    310: 
                    311: {
                    312: 
                    313:        post_sig(curproc, sig);
                    314: 
                    315:        check_sigs();
                    316: 
                    317: }
                    318: 
                    319: 
                    320: 
                    321: #ifdef EXCEPTION_SIGS
                    322: 
                    323: /* exception numbers corresponding to signals */
                    324: 
                    325: char excep_num[NSIG] =
                    326: 
                    327: { 0, 0, 0, 0,
                    328: 
                    329:   4,                   /* SIGILL == illegal instruction */
                    330: 
                    331:   9,                   /* SIGTRAP == trace trap        */
                    332: 
                    333:   4,                   /* pretend SIGABRT is also illegal instruction */
                    334: 
                    335:   8,                   /* SIGPRIV == privileged instruction exception */
                    336: 
                    337:   5,                   /* SIGFPE == divide by zero */
                    338: 
                    339:   0, 2,                        /* SIGBUS == bus error */
                    340: 
                    341:   3                    /* SIGSEGV == address error */
                    342: 
                    343: /* everything else gets zeros */
                    344: 
                    345: };
                    346: 
                    347: 
                    348: 
                    349: /* a "0" means we don't print a message when it happens -- typically the
                    350: 
                    351:    user is expecting a synchronous signal, so we don't need to report it
                    352: 
                    353: */
                    354: 
                    355: 
                    356: 
                    357: const char *signames[NSIG] = { 0,
                    358: 
                    359: 0, 0, 0, "ILLEGAL INSTRUCTION", "TRACE TRAP",
                    360: 
                    361: 0, "PRIVILEGE VIOLATION", "DIVISION BY ZERO", 0, "BUS ERROR",
                    362: 
                    363: "ADDRESS ERROR", "BAD SYSTEM CALL", 0, 0, 0,
                    364: 
                    365: 0, 0, 0, 0, 0,
                    366: 
                    367: 0, 0, 0, "CPU TIME EXHAUSTED", "FILE TOO BIG",
                    368: 
                    369: 0, 0, 0, 0, 0
                    370: 
                    371: };
                    372: 
                    373: 
                    374: 
                    375: /*
                    376: 
                    377:  * replaces the TOS "show bombs" routine: for now, print the name of the
                    378: 
                    379:  * interrupt on the console, and save info on the crash in the appropriate
                    380: 
                    381:  * system area
                    382: 
                    383:  */
                    384: 
                    385: 
                    386: 
                    387: void
                    388: 
                    389: bombs(sig)
                    390: 
                    391:        int sig;
                    392: 
                    393: {
                    394: 
                    395:        long *procinfo = (long *)0x380L;
                    396: 
                    397:        int i;
                    398: 
                    399:        CONTEXT *crash;
                    400: 
                    401: 
                    402: 
                    403:        if (signames[sig]) {
                    404: 
                    405:                ALERT("%s: User PC=%lx (basepage=%lx)",
                    406: 
                    407:                        signames[sig],
                    408: 
                    409:                        curproc->ctxt[SYSCALL].pc, curproc->base);
                    410: 
                    411: 
                    412: 
                    413: /* save the processor state at crash time */
                    414: 
                    415: /* assumes that "crash time" is the context curproc->ctxt[SYSCALL] */
                    416: 
                    417: /* BUG: this is not true if the crash happened in the kernel; in the
                    418: 
                    419:  * latter case, the crash context wasn't saved anywhere.
                    420: 
                    421:  */
                    422: 
                    423:                crash = &curproc->ctxt[SYSCALL];
                    424: 
1.1.1.2 ! root      425:                *procinfo++ = 0x12345678L;      /* magic flag for valid info */
1.1       root      426: 
                    427:                for (i = 0; i < 15; i++)
                    428: 
                    429:                        *procinfo++ = crash->regs[i];
                    430: 
                    431:                *procinfo++ = crash->ssp;
                    432: 
                    433:                *procinfo++ = ((long)excep_num[sig]) << 24L;
                    434: 
1.1.1.2 ! root      435:                *procinfo = crash->usp;
1.1       root      436: 
                    437: 
                    438: 
                    439: /* we're also supposed to save some info from the supervisor stack. it's not
                    440: 
                    441:  * clear what we should do for MiNT, since most of the stuff that used to be
                    442: 
                    443:  * on the stack has been put in the CONTXT struct. Moreover, we don't want
                    444: 
                    445:  * to crash because of an attempt to access illegal memory. Hence, we do
                    446: 
                    447:  * nothing here...
                    448: 
                    449:  */
                    450: 
                    451:        }
                    452: 
                    453: }
                    454: 
                    455: #endif
                    456: 
                    457: 
                    458: 
                    459: /*
                    460: 
                    461:  * handle_sig: do whatever is appropriate to handle a signal
                    462: 
                    463:  */
                    464: 
                    465: 
                    466: 
                    467: static long unwound_stack = 0;
                    468: 
                    469: 
                    470: 
                    471: void
                    472: 
                    473: handle_sig(sig)
                    474: 
                    475:        int sig;
                    476: 
                    477: {
                    478: 
                    479:        long oldstack, newstack;
                    480: 
                    481:        long *stack;
                    482: 
                    483:        CONTEXT *call, oldsysctxt, newcurrent;
                    484: 
                    485:        extern void sig_return();
                    486: 
                    487: 
                    488: 
                    489:        if (curproc->sighandle[sig] == SIG_IGN)
                    490: 
                    491:                return;
                    492: 
                    493:        else if (curproc->sighandle[sig] == SIG_DFL) {
                    494: 
                    495: _default:
                    496: 
                    497:                switch(sig) {
                    498: 
                    499: #if 0
                    500: 
                    501: /* Note: SIGNULL is filtered out in dossig.c and is never actually
                    502: 
                    503:  * delivered (its only purpose for the user is to test for the existence of
                    504: 
                    505:  * a process, it isn't a real signal). The kernel uses SIGNULL
                    506: 
                    507:  * internally, but all such code does the signal handling "by hand"
                    508: 
                    509:  * and so no default handling is necessary.
                    510: 
                    511:  */
                    512: 
1.1.1.2 ! root      513:                case SIGNULL:
1.1       root      514: 
                    515: #endif
                    516: 
1.1.1.2 ! root      517:                case SIGWINCH:
1.1       root      518: 
1.1.1.2 ! root      519:                case SIGCHLD:
1.1       root      520: 
1.1.1.2 ! root      521:                        return;         /* do nothing */
1.1       root      522: 
1.1.1.2 ! root      523:                case SIGSTOP:
1.1       root      524: 
1.1.1.2 ! root      525:                case SIGTSTP:
1.1       root      526: 
1.1.1.2 ! root      527:                case SIGTTIN:
1.1       root      528: 
1.1.1.2 ! root      529:                case SIGTTOU:
1.1       root      530: 
1.1.1.2 ! root      531:                        stop(sig);
1.1       root      532: 
1.1.1.2 ! root      533:                        return;
1.1       root      534: 
1.1.1.2 ! root      535:                case SIGCONT:
1.1       root      536: 
1.1.1.2 ! root      537:                        curproc->sigpending &= ~STOPSIGS;
1.1       root      538: 
1.1.1.2 ! root      539:                        return;
1.1       root      540: 
                    541: 
                    542: 
1.1.1.2 ! root      543: /* here are the fatal signals. for SIGINT, we use p_term(-32) so that
1.1       root      544: 
1.1.1.2 ! root      545:  * TOS programs that catch ^C via the vector at 0x400 and which expect
1.1       root      546: 
1.1.1.2 ! root      547:  * TOS's error code (-32) to be sent will work. For most other signals,
1.1       root      548: 
1.1.1.2 ! root      549:  * we p_term with an error code; for SIGKILL, we don't want to allow
1.1       root      550: 
1.1.1.2 ! root      551:  * the program any chance to recover, so we call terminate() directly
1.1       root      552: 
1.1.1.2 ! root      553:  * to avoid calling through to the user's terminate vector.
1.1       root      554: 
1.1.1.2 ! root      555:  */
1.1       root      556: 
1.1.1.2 ! root      557:                case SIGINT:            /* ^C */
1.1       root      558: 
1.1.1.2 ! root      559:                        if (curproc->domain == DOM_TOS) {
1.1       root      560: 
1.1.1.2 ! root      561:                                p_term(-32);
1.1       root      562: 
1.1.1.2 ! root      563:                                return;
1.1       root      564: 
1.1.1.2 ! root      565:                        }
        !           566: 
        !           567:                        /* otherwise, fall through */
1.1       root      568: 
1.1.1.2 ! root      569:                default:
1.1       root      570: 
                    571: #ifdef EXCEPTION_SIGS
                    572: 
1.1.1.2 ! root      573:                        bombs(sig); /* tell the user what happened */
1.1       root      574: 
                    575: #endif
                    576: 
1.1.1.2 ! root      577:        /* the "sigmask" check is in case a bus error happens in the user's
        !           578: 
        !           579:         * term_vec code; we don't want to get stuck in an infinite loop!
        !           580: 
        !           581:         */
        !           582: 
        !           583:                        if ((curproc->sigmask & 1L) || sig == SIGKILL)
        !           584: 
1.1       root      585:                                terminate(sig << 8, ZOMBIE_Q);
                    586: 
1.1.1.2 ! root      587:                        else
        !           588: 
        !           589:                                p_term(sig << 8);
        !           590: 
1.1       root      591:                }
                    592: 
                    593:        }
                    594: 
                    595:        else {          /* user wants to handle it himself */
                    596: 
                    597: 
                    598: 
                    599: /* another kludge: there is one case in which the p_sigreturn mechanism
                    600: 
                    601:  * is invoked by the kernel, namely when the user calls Supexec()
                    602: 
                    603:  * or when s/he installs a handler for the GEMDOS terminate vector (#0x102)
                    604: 
                    605:  * and the program terminates. MiNT fakes the call to user code with
                    606: 
                    607:  * signal 0 (SIGNULL); programs that longjmp out of the user function
                    608: 
                    609:  * and are later sent back to it again (e.g. if ^C keeps getting pressed
                    610: 
                    611:  * and a terminate vector has been installed) will grow the stack without
                    612: 
                    613:  * bound unless we watch for this case.
                    614: 
                    615:  *
                    616: 
                    617:  * Solution (sort of): whenever Pterm() is called, we unwind the
                    618: 
                    619:  * stack; otherwise, we let it grow, so that nested Supexec()
                    620: 
                    621:  * calls work.
                    622: 
                    623:  *
                    624: 
                    625:  * Note that SIGNULL is thrown away when sent by user processes, 
                    626: 
                    627:  * and the user can't mask it (it's UNMASKABLE), so there is
                    628: 
                    629:  * is no possibility of confusion with anything the user does.
                    630: 
                    631:  */
                    632: 
                    633:                if (sig == 0) {
                    634: 
                    635:        /* p_term() sets sigmask to let us know to do Psigreturn */
                    636: 
                    637:                        if (curproc->sigmask & 1L) {
                    638: 
                    639:                                p_sigreturn();
                    640: 
                    641:                                curproc->sigmask &= ~1L;
                    642: 
                    643:                        } else {
                    644: 
                    645:                                unwound_stack = 0;
                    646: 
                    647:                        }
                    648: 
                    649:                }
                    650: 
                    651: 
                    652: 
                    653:                call = &curproc->ctxt[SYSCALL];
                    654: 
                    655: /*
                    656: 
                    657:  * what we do is build two fake stack frames; the bottom one is
                    658: 
                    659:  * for a call to the user function, with (long)parameter being the
                    660: 
                    661:  * signal number; the top one is for sig_return.
                    662: 
                    663:  * When the user function returns, it returns to sig_return, which
                    664: 
                    665:  * calls into the kernel to restore the context in prev_ctxt
                    666: 
                    667:  * (thus putting us back here). We can then continue on our way.
                    668: 
                    669:  */
                    670: 
                    671: 
                    672: 
                    673: /* set a new system stack, with a bit of buffer space */
                    674: 
                    675:                oldstack = curproc->sysstack;
                    676: 
                    677:                newstack = ((long) ( (&newcurrent) - 3 )) - 12;
                    678: 
                    679: 
                    680: 
                    681:                if (newstack < (long)curproc->stack + ISTKSIZE + 256) {
                    682: 
                    683:                        ALERT("stack overflow");
                    684: 
                    685:                        goto _default;
                    686: 
                    687:                }
                    688: 
                    689:                else if ((long) curproc->stack + STKSIZE < newstack) {
                    690: 
                    691:                        FATAL("system stack not in proc structure");
                    692: 
                    693:                }
                    694: 
                    695: 
                    696: 
                    697: /* unwound_stack is set by p_sigreturn() */
                    698: 
                    699:                if (sig == 0 && unwound_stack)
                    700: 
                    701:                        curproc->sysstack = unwound_stack;
                    702: 
                    703:                else
                    704: 
                    705:                        curproc->sysstack = newstack;
                    706: 
                    707:                oldsysctxt = *call;
                    708: 
                    709:                stack = (long *)(call->sr & 0x2000 ? call->ssp :
                    710: 
                    711:                                call->usp);
                    712: 
                    713: /*
                    714: 
                    715:    Hmmm... here's another potential problem for the signal 0 terminate
                    716: 
                    717:    vector: if the program keeps returning back to user mode without
                    718: 
                    719:    worrying about the supervisor stack, we'll eventually overflow it.
                    720: 
                    721:    However, if the program is in supervisor mode itself, then we don't
                    722: 
                    723:    want to stomp on its stack. Temporary solution: ignore the problem,
                    724: 
1.1.1.2 ! root      725:    the stack's only growing 12 bytes at a time.
1.1       root      726: 
                    727:  */
                    728: 
1.1.1.2 ! root      729: /*
        !           730: 
        !           731:  * in addition to the signal number we stuff the vector offset on the
        !           732: 
        !           733:  * stack; if the user is interested they can sniff it, if not ignoring
        !           734: 
        !           735:  * it needs no action on their part. Why do we need this? So that a
        !           736: 
        !           737:  * single SIGFPE handler (for example) can discriminate amongst the
        !           738: 
        !           739:  * multiple things which may get thrown its way
        !           740: 
        !           741:  */
        !           742: 
        !           743:                *(--stack) = (long)call->sfmt & 0xfff;
        !           744: 
1.1       root      745:                *(--stack) = (long)sig;
                    746: 
                    747:                *(--stack) = (long)sig_return;
                    748: 
                    749:                if (call->sr & 0x2000)
                    750: 
                    751:                        call->ssp = ((long) stack);
                    752: 
                    753:                else
                    754: 
                    755:                        call->usp = ((long) stack);
                    756: 
                    757:                call->pc = (long) curproc->sighandle[sig];
                    758: 
1.1.1.2 ! root      759:                call->sfmt = call->fstate[0] = 0;       /* don't restart FPU communication */
        !           760: 
1.1       root      761: 
                    762: 
                    763:                ((long *)curproc->sysstack)[1] = FRAME_MAGIC;
                    764: 
                    765:                ((long *)curproc->sysstack)[2] = oldstack;
                    766: 
                    767:                ((long *)curproc->sysstack)[3] = sig;
                    768: 
                    769: 
                    770: 
1.1.1.2 ! root      771:                if (curproc->sigflags[sig] & SA_RESET) {
        !           772: 
        !           773:                        curproc->sighandle[sig] = SIG_DFL;
        !           774: 
        !           775:                        curproc->sigflags[sig] &= ~SA_RESET;
        !           776: 
        !           777:                }
        !           778: 
        !           779:                        
        !           780: 
1.1       root      781:                if (save_context(&newcurrent) == 0 ) {
                    782: 
                    783: /*
                    784: 
                    785:  * go do the signal; eventually, we'll restore this context (unless the
                    786: 
                    787:  * user longjmp'd out of his signal handler). while the user is handling
                    788: 
                    789:  * the signal, it's masked out to prevent race conditions. p_sigreturn()
                    790: 
                    791:  * will unmask it for us when the user is finished.
                    792: 
                    793:  */
                    794: 
                    795:                        newcurrent.regs[0] = CTXT_MAGIC;
                    796: 
                    797:                                /* set D0 so next return is different */
                    798: 
                    799:                        assert(curproc->magic == CTXT_MAGIC);
                    800: 
                    801:                        leave_kernel();
                    802: 
                    803:                        restore_context(call);
                    804: 
                    805:                }
                    806: 
                    807: /*
                    808: 
                    809:  * OK, we get here from p_sigreturn, via the user returning from
                    810: 
                    811:  * the handler to sig_return. Restoring the stack and unmasking the
                    812: 
                    813:  * signal have been done already for us by p_sigreturn.
                    814: 
                    815:  * We should just restore the old system call context
                    816: 
                    817:  * and continue with whatever it was we were doing.
                    818: 
                    819:  */
                    820: 
1.1.1.2 ! root      821:                TRACE(("done handling signal"));
1.1       root      822: 
                    823:                curproc->ctxt[SYSCALL] = oldsysctxt;
                    824: 
                    825:                assert(curproc->magic == CTXT_MAGIC);
                    826: 
                    827:        }
                    828: 
                    829: }
                    830: 
                    831: 
                    832: 
                    833: /*
                    834: 
                    835:  * the p_sigreturn system call
                    836: 
                    837:  * When called by the user from inside a signal handler, it indicates a
                    838: 
                    839:  * desire to restore the old stack frame prior to a longjmp() out of
                    840: 
                    841:  * the handler.
                    842: 
                    843:  * When called from the sig_return module, it indicates that the user
                    844: 
                    845:  * is finished a handler, and we should not only restore the stack
                    846: 
                    847:  * frame but also the old context we were working in (which is on the
                    848: 
                    849:  * system call stack -- see handle_sig).
                    850: 
                    851:  * The "valid_return" variable is 0 in the first case, 1 in the second.
                    852: 
                    853:  */
                    854: 
                    855: 
                    856: 
                    857: short valid_return;
                    858: 
                    859: 
                    860: 
1.1.1.2 ! root      861: long ARGS_ON_STACK
1.1       root      862: 
                    863: p_sigreturn()
                    864: 
                    865: {
                    866: 
                    867:        CONTEXT *oldctxt;
                    868: 
                    869:        long *frame;
                    870: 
                    871:        long sig;
                    872: 
                    873: 
                    874: 
                    875:        unwound_stack = 0;
                    876: 
                    877: top:
                    878: 
                    879:        frame = (long *)curproc->sysstack;
                    880: 
                    881:        frame++;        /* frame should point at FRAME_MAGIC, now */
                    882: 
                    883:        sig = frame[2];
                    884: 
                    885:        if (*frame != FRAME_MAGIC || (sig < 0) || (sig >= NSIG)) {
                    886: 
                    887:                FATAL("Psigreturn: system stack corrupted");
                    888: 
                    889:        }
                    890: 
                    891:        if (frame[1] == 0) {
                    892: 
1.1.1.2 ! root      893:                DEBUG(("Psigreturn: frame at %lx points to 0", frame-1));
1.1       root      894: 
                    895:                return 0;
                    896: 
                    897:        }
                    898: 
                    899:        unwound_stack = curproc->sysstack;
                    900: 
1.1.1.2 ! root      901:        TRACE(("Psigreturn(%d)", (int)sig));
1.1       root      902: 
                    903: 
                    904: 
                    905:        curproc->sysstack = frame[1];   /* restore frame */
                    906: 
                    907:        curproc->sigmask &= ~(1L<<sig); /* unblock signal */
                    908: 
                    909: 
                    910: 
                    911:        if (!valid_return) {
                    912: 
                    913: /* here, the user is telling us that a longjmp out of a signal handler is
                    914: 
                    915:  * about to occur; so we should unwind *all* the signal frames
                    916: 
                    917:  */
                    918: 
                    919:                goto top;
                    920: 
                    921:        }
                    922: 
                    923:        else {
                    924: 
                    925:                valid_return = 0;
                    926: 
                    927:                oldctxt = ((CONTEXT *)(&frame[2])) + 3;
                    928: 
                    929:                if (oldctxt->regs[0] != CTXT_MAGIC) {
                    930: 
                    931:                        FATAL("p_sigreturn: corrupted context");
                    932: 
                    933:                }
                    934: 
                    935:                assert(curproc->magic == CTXT_MAGIC);
                    936: 
                    937:                restore_context(oldctxt);
                    938: 
                    939:                return 0;       /* dummy -- this isn't reached */
                    940: 
                    941:        }
                    942: 
                    943: }
                    944: 
                    945: 
                    946: 
                    947: /*
                    948: 
                    949:  * stop a process because of signal "sig"
                    950: 
                    951:  */
                    952: 
                    953: 
                    954: 
                    955: void
                    956: 
                    957: stop(sig)
                    958: 
                    959:        int sig;
                    960: 
                    961: {
                    962: 
                    963:        unsigned int code;
                    964: 
                    965:        unsigned long oldmask;
                    966: 
                    967:        PROC *p;
                    968: 
                    969: 
                    970: 
                    971:        code = sig << 8;
                    972: 
                    973: 
                    974: 
                    975:        if (curproc->pid == 0) {
                    976: 
                    977:                ALERT("attempt to stop MiNT");
                    978: 
                    979:                return;
                    980: 
                    981:        }
                    982: 
                    983: 
                    984: 
                    985: /* notify parent */
                    986: 
1.1.1.2 ! root      987:        if (curproc->ptracer) {
1.1       root      988: 
1.1.1.2 ! root      989:                p = curproc->ptracer;
1.1       root      990: 
                    991:                post_sig(p, SIGCHLD);
                    992: 
1.1.1.2 ! root      993:        } else {
        !           994: 
        !           995:                p = pid2proc(curproc->ppid);
        !           996: 
        !           997:                if (p && !(p->sigflags[SIGCHLD] & SA_NOCLDSTOP))
        !           998: 
        !           999:                        post_sig(p, SIGCHLD);
        !          1000: 
1.1       root     1001:        }
                   1002: 
                   1003: 
                   1004: 
                   1005:        oldmask = curproc->sigmask;
                   1006: 
                   1007: 
                   1008: 
1.1.1.2 ! root     1009:        if ((1L << sig) & STOPSIGS) {
        !          1010: 
        !          1011:                /* mask out most signals */
        !          1012: 
        !          1013:                curproc->sigmask |= ~(UNMASKABLE | SIGTERM);
        !          1014: 
        !          1015:        }
1.1       root     1016: 
1.1.1.2 ! root     1017:        else
        !          1018: 
        !          1019:                assert(curproc->ptracer);
1.1       root     1020: 
                   1021: 
                   1022: 
                   1023: /* sleep until someone signals us awake */
                   1024: 
                   1025:        sleep(STOP_Q, (long) code | 0177);
                   1026: 
                   1027: 
                   1028: 
                   1029: /* when we wake up, restore the signal mask */
                   1030: 
                   1031:        curproc->sigmask = oldmask;
                   1032: 
                   1033: 
                   1034: 
                   1035: /* and discard any signals that would cause us to stop again */
                   1036: 
                   1037:        curproc->sigpending &= ~STOPSIGS;
                   1038: 
                   1039: }
                   1040: 
                   1041: 
                   1042: 
                   1043: /*
                   1044: 
                   1045:  * interrupt handlers to raise SIGBUS, SIGSEGV, etc. Note that for
                   1046: 
                   1047:  * really fatal errors we reset the handler to SIG_DFL, so that
                   1048: 
                   1049:  * a second such error kills us
                   1050: 
                   1051:  */
                   1052: 
                   1053: 
                   1054: 
                   1055: void
                   1056: 
                   1057: exception(sig)
                   1058: 
                   1059:        int sig;
                   1060: 
                   1061: {
                   1062: 
1.1.1.2 ! root     1063:        curproc->sigflags[sig] |= SA_RESET;
        !          1064: 
        !          1065:        TRACE(("exception #%d raised", sig));
1.1       root     1066: 
                   1067:        raise(sig);
                   1068: 
                   1069: }
                   1070: 
                   1071: 
                   1072: 
                   1073: void
                   1074: 
                   1075: sigbus()
                   1076: 
                   1077: {
                   1078: 
                   1079:        exception(SIGBUS);
                   1080: 
                   1081: }
                   1082: 
                   1083: 
                   1084: 
                   1085: void
                   1086: 
                   1087: sigaddr()
                   1088: 
                   1089: {
                   1090: 
                   1091:        exception(SIGSEGV);
                   1092: 
                   1093: }
                   1094: 
                   1095: 
                   1096: 
                   1097: void
                   1098: 
                   1099: sigill()
                   1100: 
                   1101: {
                   1102: 
                   1103:        exception(SIGILL);
                   1104: 
                   1105: }
                   1106: 
                   1107: 
                   1108: 
                   1109: void
                   1110: 
                   1111: sigpriv()
                   1112: 
                   1113: {
                   1114: 
                   1115:        raise(SIGPRIV);
                   1116: 
                   1117: }
                   1118: 
                   1119: 
                   1120: 
                   1121: void
                   1122: 
                   1123: sigfpe()
                   1124: 
                   1125: {
                   1126: 
1.1.1.2 ! root     1127:        extern short fpu;       /* in main.c */
        !          1128: 
        !          1129:        
        !          1130: 
        !          1131:        if (fpu) {
        !          1132: 
        !          1133:                CONTEXT *ctxt;
        !          1134: 
        !          1135: 
        !          1136: 
        !          1137:                ctxt = &curproc->ctxt[SYSCALL];
        !          1138: 
        !          1139: 
        !          1140: 
        !          1141:        /* 0x1f38 is a Motorola magic cookie to detect a 68882 idle state frame */
        !          1142: 
        !          1143:                if (*(ushort *)ctxt->fstate == 0x1f38 && 
        !          1144: 
        !          1145:                    (ctxt->sfmt & 0xfff) >= 0xc0L && (ctxt->sfmt & 0xfff) <= 0xd8L) {
        !          1146: 
        !          1147:                        /* fix a bug in the 68882 - Motorola call it a feature :-) */
        !          1148: 
        !          1149:                        ctxt->fstate[ctxt->fstate[1]] |= 1 << 3;
        !          1150: 
        !          1151:                }
        !          1152: 
        !          1153:        }
        !          1154: 
1.1       root     1155:        raise(SIGFPE);
                   1156: 
                   1157: }
                   1158: 
                   1159: 
                   1160: 
                   1161: void
                   1162: 
                   1163: sigtrap()
                   1164: 
                   1165: {
                   1166: 
                   1167:        raise(SIGTRAP);
                   1168: 
                   1169: }
                   1170: 
1.1.1.2 ! root     1171: 
        !          1172: 
        !          1173: void
        !          1174: 
        !          1175: haltformat()
        !          1176: 
        !          1177: {
        !          1178: 
        !          1179:        FATAL("halt: invalid stack frame format");
        !          1180: 
        !          1181: }
        !          1182: 
        !          1183: 
        !          1184: 
        !          1185: void
        !          1186: 
        !          1187: haltcpv()
        !          1188: 
        !          1189: {
        !          1190: 
        !          1191:        FATAL("halt: coprocessor protocol violation");
        !          1192: 
        !          1193: }
        !          1194: 

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