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Annotation of 42BSD/ucb/pascal/pdx/machine/setbp.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982 Regents of the University of California */
        !             2: 
        !             3: static char sccsid[] = "@(#)setbp.c 1.1 1/18/82";
        !             4: 
        !             5: /*
        !             6:  * Breakpoint/machine interface.
        !             7:  */
        !             8: 
        !             9: #include "defs.h"
        !            10: #include <signal.h>
        !            11: #include "machine.h"
        !            12: #include "process.h"
        !            13: #include "main.h"
        !            14: #include "pxops.h"
        !            15: #include "process/process.rep"
        !            16: 
        !            17: #define BP_OP          O_BPT           /* breakpoint trap */
        !            18: #define BP_ERRNO       SIGILL          /* signal received at a breakpoint */
        !            19: 
        !            20: /*
        !            21:  * Setting a breakpoint at a location consists of saving
        !            22:  * the half-word at the location and poking a BP_OP there.
        !            23:  *
        !            24:  * We save the locations and half-words on a list for use in unsetting.
        !            25:  */
        !            26: 
        !            27: typedef struct savelist SAVELIST;
        !            28: 
        !            29: struct savelist {
        !            30:        ADDRESS location;
        !            31:        short save;
        !            32:        short refcount;
        !            33:        SAVELIST *link;
        !            34: };
        !            35: 
        !            36: LOCAL SAVELIST *savelist;
        !            37: 
        !            38: /*
        !            39:  * Set a breakpoint at the given address.  Only save the half-word there
        !            40:  * if it's not already a breakpoint.
        !            41:  */
        !            42: 
        !            43: setbp(addr)
        !            44: ADDRESS addr;
        !            45: {
        !            46:        short w;
        !            47:        short save;
        !            48:        register SAVELIST *newsave, *s;
        !            49: 
        !            50:        if (option('b')) {
        !            51:                printf("setting breakpoint at %d\n", addr);
        !            52:                fflush(stdout);
        !            53:        }
        !            54:        for (s = savelist; s != NIL; s = s->link) {
        !            55:                if (s->location == addr) {
        !            56:                        s->refcount++;
        !            57:                        return;
        !            58:                }
        !            59:        }
        !            60:        iread(&save, addr, sizeof(save));
        !            61:        newsave = alloc(1, SAVELIST);
        !            62:        newsave->location = addr;
        !            63:        newsave->save = save;
        !            64:        newsave->refcount = 1;
        !            65:        newsave->link = savelist;
        !            66:        savelist = newsave;
        !            67:        w = BP_OP;
        !            68:        iwrite(&w, addr, sizeof(w));
        !            69: }
        !            70: 
        !            71: /*
        !            72:  * Unset a breakpoint; unfortunately we have to search the SAVELIST
        !            73:  * to find the saved value.  The assumption is that the SAVELIST will
        !            74:  * usually be quite small.
        !            75:  */
        !            76: 
        !            77: unsetbp(addr)
        !            78: ADDRESS addr;
        !            79: {
        !            80:        register SAVELIST *s, *prev;
        !            81: 
        !            82:        if (option('b')) {
        !            83:                printf("unsetting breakpoint at %d\n", addr);
        !            84:                fflush(stdout);
        !            85:        }
        !            86:        prev = NIL;
        !            87:        for (s = savelist; s != NIL; s = s->link) {
        !            88:                if (s->location == addr) {
        !            89:                        iwrite(&s->save, addr, sizeof(s->save));
        !            90:                        s->refcount--;
        !            91:                        if (s->refcount == 0) {
        !            92:                                if (prev == NIL) {
        !            93:                                        savelist = s->link;
        !            94:                                } else {
        !            95:                                        prev->link = s->link;
        !            96:                                }
        !            97:                                dispose(s);
        !            98:                        }
        !            99:                        return;
        !           100:                }
        !           101:                prev = s;
        !           102:        }
        !           103:        panic("unsetbp: couldn't find address %d", addr);
        !           104: }
        !           105: 
        !           106: /*
        !           107:  * Predicate to test if the reason the process stopped was because
        !           108:  * of a breakpoint.
        !           109:  */
        !           110: 
        !           111: BOOLEAN isbperr()
        !           112: {
        !           113:        register PROCESS *p;
        !           114: 
        !           115:        p = process;
        !           116:        return(p->status==STOPPED && p->signo==BP_ERRNO);
        !           117: }

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