source: rtems/c/src/lib/librdbg/servbkpt.c @ 0bf2ff8

/*
 **********************************************************************
 *
 *  Component:  RDB servers
 *  Module:     servbkpt.c
 *
 *  Synopsis:   Management of breakpoints
 *
 **********************************************************************
 */

#include <sys/errno.h>
#include <assert.h>   
#include <rdbg/rdbg.h>
#include <rdbg/servrpc.h>

/*----- Macros -----*/

#define BKPT0(plst)     ((BASE_BREAK*)(plst)->break_list)
#define BKPT_INCR       5       /* how many bkpt slots alloc at a time */

#define BKPT_OVER(plst,idx,addr,size) \
    ((plst)->break_list[idx].ee_loc + BREAK_SIZE > (UINT32) (addr) \
    &&  (plst)->break_list[idx].ee_loc < (UINT32) (addr) + (size))

#define BKPT_SLOTS \
        (sizeof ((xdr_break*) 0)->thread_list / \
         sizeof ((xdr_break*) 0)->thread_list [0])


    /*
     *  BreakAlloc - alloc a breakpoint entry.
     *
     *  This is a generic routine to insert an entry in the
     *  breakpoint list. It returns the number of entry just
     *  created. It returns -1 if failed.
     */

    static int
BreakAlloc (PID_LIST* plst, Boolean normal)
{
    int         idx, len;
    xdr_break*  blst;

    if (!normal) {              /* want 0 entry */
        if (plst->break_list) {
            return(0);          /* already there */
        }
        idx = 1;                /* force alloc below */
    } else {
        for (idx = 1; idx < (int)plst->break_alloc; idx++) {
            if (plst->break_list[idx].type == BRKT_NONE) {
                    /* got a free one */
                memset(&plst->break_list[idx], 0, sizeof(xdr_break));
                return(idx);            /* found one */
            }
        }
    }
        /* idx is the requested entry */

    if (idx >= (int)plst->break_alloc) { /* need more space */
        len = plst->break_alloc + BKPT_INCR;
        blst = (xdr_break*)Realloc(plst->break_list, len*sizeof(xdr_break));
        if (!blst) {
            return(-1);         /* failed, no space */
        }
        plst->break_alloc = len;        /* got more */
        plst->break_list = blst;

            /* Clear new space */
        memset(blst + len - BKPT_INCR, 0, BKPT_INCR * sizeof(xdr_break));
        idx = len - BKPT_INCR;          /* next available */
        if (!idx) {
            idx = 1;                    /* for normal cases */
        }
    }
    return(normal ? idx : 0);   /* return it */
}

    /*
     *  BreakSet - set a breakpoint in process
     *
     *  Returns the number or -1/errno.
     */

#ifdef DDEBUG
static const char* BreakTypes[] = {
    "NONE",   "INSTR", "READ",    "WRITE",
    "ACCESS", "EXEC",  "OS_CALL", "OS_SWITCH",
    "STEPEMUL"
};

#define BN_MAX          (sizeof BreakTypes / sizeof BreakTypes[0])
#define BREAK_NAME(t)   ((unsigned) (t) < BN_MAX ? BreakTypes[t] : "???")
#endif

    int
BreakSet (PID_LIST* plst, int conn_idx, xdr_break* bkpt)
{
    int pid = plst->pid;
    int type = bkpt->type;
    void* addr = (void *) bkpt->ee_loc;
    int idx;
    int data;
    
    DPRINTF(("BreakSet: type %d (%s) at 0x%x th %d ee_type %d len %d "
        "pass %d curr %d list %d %d %d %d\n", type, BREAK_NAME(type),
        (int) addr,
        bkpt->thread_spec, bkpt->ee_type, bkpt->length, bkpt->pass_count,
        bkpt->curr_pass, bkpt->thread_list [0], bkpt->thread_list [1],
        bkpt->thread_list [2], bkpt->thread_list [3]));

    idx = BreakAlloc(plst, True); /* get entry */
    if (idx < 0) {              /* no memory */
        setErrno(ENOMEM);       /* set for safety */
        return -1;              /* return the error */
    }

    data = TgtPtrace(RPT_PEEKTEXT, pid, addr, 0, NULL); /* current */
    if (getErrno()) {
      return -1;                /* failed, return the error */
    }
    if (IS_BREAK(data)) {       /* There is already a break here */
      DPRINTF(("BreakSet: already have soft bkpt at %x\n", addr));
      if (type == BRKT_STEPEMUL) {
        ++BKPT0 (plst)->pad1;
        return 1;       /* Any non-error value is OK */
      }
      setErrno(EBUSY);
      return -1;
    }

    TgtPtrace(RPT_POKETEXT, pid, addr, SET_BREAK(data), NULL);

    if (getErrno()) {
      return -1;
    }

    plst->break_list[idx] = *bkpt;
    plst->break_list[idx].ee_type = data; /* saved data */
        
    /* Inform other owners */
    if (type != BRKT_STEPEMUL) {
        TgtNotifyAll (plst - pid_list, BMSG_BREAK, 1 /*added*/, idx,
            conn_idx, False);
    } else {
        ++BKPT0 (plst)->pad1;
    }
        /* Return the number */
    setErrno(0);                /* Just in case */
    return idx;
}

    int
BreakSetAt (PID_LIST* plst, int conn_idx, unsigned long addr, break_type type)
{
    xdr_break xb;

    memset (&xb, 0, sizeof xb);
    xb.type = type;
    xb.ee_loc = addr;
    return BreakSet (plst, conn_idx, &xb);
}

/*----- Find a breakpoint by address -----*/

    int
BreakGetIndex(PID_LIST* plst, void* addr)
{
    int idx;
    int data = -1;

    if (!plst->break_alloc) {
        setErrno(EFAULT);
        return -1;
    }
    for (idx = 1; idx < (int)plst->break_alloc; idx++) {
        if ((u_long) addr == plst->break_list [idx].ee_loc) {
            data = idx;
            break;
        }              
    }
    return data;
}

/*----- Getting information about breakpoint -----*/

    /*
     *  If data > 0, fill "bkpt" with information about breakpoint
     *  and return the number of the next one.
     *  If data == 0, return the count of breakpoints.
     */

    int
BreakGet (const PID_LIST* plst, int data, xdr_break* bkpt)
{
    int idx;

    if (!data) {                /* just count them */
        for (idx = 1; idx < (int)plst->break_alloc; idx++) {
            if (plst->break_list[idx].type != BRKT_NONE) {
                data++;
            }
        }
        return data;    /* count */
    }
    if ((unsigned) data >= plst->break_alloc) {
            /* out of range */
        setErrno(EFAULT);               /* closest match */
        return -1;
    }
        /* get it and say which is next */
    *bkpt = plst->break_list[data];
    for (idx = (int)data+1; idx < (int)plst->break_alloc; idx++) {
        if (plst->break_list[idx].type != BRKT_NONE) {
            return idx;
        }
    }
    return 0;           /* otherwise returns 0 for no more */
}

/*----- Clearing bkpts -----*/

    /*
     *  BreakClear - clear one (if data != 0) or all breakpoints
     *  (if data == 0). Return the number of bkpts cleared.
     *  If (data == -1), remove step-emulation breakpoints.
     */

    int
BreakClear (PID_LIST* plst, int conn_idx, int data)
{
    int pid_idx = plst - pid_list;
    int idx;
    int cleared = 0;
    int clearStepEmul = 0;
    int terminated = PROC_TERMINATED (plst);
    int stepEmulCount = 0;

        /* break handle in data */
    if (!plst->break_alloc) {           /* there are no breaks */
        DPRINTF (("BreakClear: no bkpts defined.\n"));
        setErrno(EFAULT);               /* closest match */
        return -1;              /* return error */
    }
    if (!data) {                                /* clear all */
        idx = 1;
        data = plst->break_alloc-1;

            /* Inform other owners */
        DPRINTF (("BreakClear: clearing all bkpts.\n"));
        TgtNotifyAll (pid_idx, BMSG_BREAK, 0 /*clr*/, 0, conn_idx, False);

    } else if (data == -1) {            /* clear all step-emul bkpts */
        DPRINTF(("BreakClear: removing %d step-emul bkpts\n",
            BKPT0 (plst)->pad1));

        stepEmulCount = BKPT0 (plst)->pad1;
        BKPT0 (plst)->pad1 = 0;

        clearStepEmul = 1;
        idx = 1;
        data = plst->break_alloc-1;
    } else if ((unsigned) data >= plst->break_alloc
           ||  plst->break_list[data].type == BRKT_NONE) {

            /* out of range */
        DPRINTF (("BreakClear: invalid bkpt %d\n", data));
        setErrno(EFAULT);               /* closest match */
        return -1;                      /* return error */
    } else {
        idx = data;
            /* Inform other owners */
        TgtNotifyAll (pid_idx, BMSG_BREAK, 0 /*clr*/, idx, conn_idx, False);
        DPRINTF (("BreakClear: clearing bkpt %d\n", data));
    }

    for (; idx <= data; idx++) {        /* clear each one */
        int type = plst->break_list[idx].type;

        if (clearStepEmul && type != BRKT_STEPEMUL) continue;

        if (type == BRKT_INSTR || (clearStepEmul && type == BRKT_STEPEMUL)) {
                /* just patch back */
            char* addr = (char *)plst->break_list[idx].ee_loc;
            int val;

            if (BKPT0 (plst)->clr_step &&  BKPT0 (plst)->last_break == idx) {
                BKPT0 (plst)->clr_step = 0; /* not needed */
            }
                /* Neighboring bytes can have breakpoints too... */
            if (! terminated) {
                setErrno (0);
                val = TgtPtrace(RPT_PEEKTEXT, plst->pid, addr, 0, NULL);
                if (getErrno()) {
                    DPRINTF (("BreakClear: addr %x not readable!\n", addr));
                    setErrno (0);       /* Forget bkpt */
                } else {
                    assert (IS_BREAK (val));
                    val = ORG_BREAK (val, (int)plst->break_list[idx].ee_type);
                    TgtPtrace(RPT_POKETEXT, plst->pid, addr, val, NULL);
                    if (getErrno()) {
                        DPRINTF (("BreakClear: addr %x not writable!\n", addr));
                        setErrno (0);
                    }
                }
            }
            ++cleared;          /* indicate cleared */
        }
        memset(&plst->break_list[idx], 0, sizeof(xdr_break));
    }
    assert (!clearStepEmul || cleared <= stepEmulCount);
    if (stepEmulCount && cleared == 0) {
        DPRINTF (("BreakClear: all STEPEMUL bkpts were shared\n"));
        return 1;
    }
    return cleared;
}

/*----- Hiding of breakpoints -----*/

    /*
     *  PatchBreak - patch original data from break into data buffer.
     *
     * Notes:
     *  - this routine patches the original data under a break into the data
     *    buffer from a ptrace read/peek. 
     */

    static void
PatchBreak (char* buff, UINT32 bstart, int bsize, UINT32 dstart, char* dvalue)
{
    int         size = BREAK_SIZE; /* default size */

        /* Must deal with all sorts of unalignments
         * (3 full overlaps, 3 unaligns)
         */
    if (bsize < BREAK_SIZE) {
            /* case where buffer is smaller than data */
        memcpy(buff, dvalue+(bstart-dstart), bsize); /* copy over */
        return;
    }
        /* buffer larger than data.
         * we need to see where break fits in buffer and whether
         * we have part of it off the end. We set bstart to be the
         * buffer offset, dtart to be the break data offset, and
         * size to be the amount to copy
         */
    if (dstart < bstart) {
            /* break before actual buffer */
        dstart = bstart-dstart; /* offset in data */
        size -= dstart;         /* amount to copy */
        bstart = 0;             /* offset in buffer */

    } else if (dstart + size > bstart + bsize) {
            /* off end */
        bstart += bsize;                /* end of buffer */
        size -= (dstart + size) - bstart;
        bstart = bsize - size;  /* come back into buffer enough */
        dstart = 0;             /* start of data */

    } else {                            /* normal case */
        bstart = dstart - bstart;       /* offset in buffer */
        dstart = 0;
    }
    memcpy(buff+bstart, dvalue+dstart, size);
}

    void
BreakHide (const PID_LIST* plst, void* addr, int data, void* addr2)
{
    int idx;

    if (!plst->break_list)      /* no breaks exist, so skip this */
        return;

        /* if breakpoints, replace */

    for (idx = 1; idx < (int)plst->break_alloc; idx++) {
        int type = plst->break_list[idx].type;

        if (type != BRKT_INSTR && type != BRKT_STEPEMUL) {
            continue;
        }
            /* break, see if overlaps */
        if (BKPT_OVER (plst, idx, addr, data)) {

                /* overlaps, patch in old value */
            PatchBreak((char *)addr2, (UINT32)addr, data, 
                plst->break_list[idx].ee_loc, 
                (char *)&plst->break_list[idx].ee_type);
        }
    }
}

/*----- Checking of breakpoint overwrites -----*/

    /*
     *  BreakOverwrite - check if memory write does not involve addresses
     *  having software breakpoints.
     */

    int
BreakOverwrite (const PID_LIST* plst, const char* addr, unsigned int size)
{
    int idx;

    if (!plst->break_list) {    /* No breaks exist */
        return 0;
    }

    for (idx = 1; idx < (int)plst->break_alloc; idx++) {
        int type = plst->break_list[idx].type;

            /* Consider only breakpoints involving modified memory */
        if (type != BRKT_INSTR && type != BRKT_STEPEMUL) {
            continue;
        }
        if (BKPT_OVER (plst, idx, addr, size)) {
            return -1;  /* overlaps */
        }
    }
    return 0;
}

/*----- Execution support -----*/

    /*
     *  BreakStepRange - Start stepping in a range.
     *
     *  Range is saved in breakpoint 0.
     */

    int
BreakStepRange (PID_LIST* plst, void* addr, int len)
{
    if (!plst->break_list) {
            /* get list */
        if (BreakAlloc (plst, False) == -1) { /* must not be any memory */
            setErrno(ENOMEM);   /* to be safe */
            return -1;          /* fails */
        }
    }
    BKPT0 (plst)->range_start = (UINT32)addr;
    BKPT0 (plst)->range_end = (UINT32)addr+(len-1);
    return 0;
}

    /*
     *  If the Program Counter is changed, consider that the
     *  current breakpoint has not been reached yet.
     */

    void
BreakPcChanged (PID_LIST* plst)
{
    if (plst->break_list) {
            /* clear break stuff */
        BKPT0 (plst)->clr_step = False;
    }
}

    /*
     *  BreakStepOff - prepare stepping off a breakpoint.
     */

    int
BreakStepOff (const PID_LIST* plst, void** paddr2)
{
    if (plst->break_list  &&  BKPT0 (plst)->clr_step) {

            /* need clear then step off break */
        int last = BKPT0 (plst)->last_break;

            /* clear break, step, then do exec */

        *paddr2 = (void*) plst->break_list[last].ee_type;

            /* Need to clr_step after TgtPtrace() when wait() returns */
        return 1;
    }
    return 0;
}

    /*
     *  BreakSteppedOff - check if just stepped off a breakpoint
     *  and re-insert it into the code.
     */

    void
BreakSteppedOff (PID_LIST* plst)
{
    if (plst->break_list  &&  BKPT0 (plst)->clr_step) {
        int idx = BKPT0 (plst)->last_break;
        int data;

        BKPT0 (plst)->clr_step = 0;

        /*
         *  Re-insert the breakpoint.
         */
        data = TgtPtrace (RPT_PEEKTEXT, plst->pid,
                          (char *)plst->break_list [idx].ee_loc, 0, NULL);
        assert (! IS_BREAK (data));
        TgtPtrace (RPT_POKETEXT, plst->pid,
                   (char *)plst->break_list[idx].ee_loc,
                   (int) SET_BREAK (data), NULL);
    }
}


    /*
     *  Returns whether a thread matches a breakpoint.
     */

    static int
BreakThreadMatch (xdr_break* xb, int thread)
{
    int slot;

    if (thread < 0) return 1;   /* Break existence check only */

    if (xb->thread_list [0] == 0) return 1;     /* Universal break */

    for (slot = 0; slot < BKPT_SLOTS; ++slot) {
        if (xb->thread_list [slot] == 0) return 0;      /* End of list */
        if (xb->thread_list [slot] == thread) return 1; /* Match */
    }
    return 0;           /* No matches found */
}


int
BreakAdjustPC (PID_LIST* plst)
{
        /* 
         *  BREAK_ADJ is the value by which the Program Counter
         *  has to be decremented after a software breakpoint
         *  is hit. It must be defined and can be zero.
         */
#if BREAK_ADJ
        /* subtract back if necessary */
    plst->regs.REG_PC -= BREAK_ADJ; /* now write back */
    TgtPtrace(RPT_SETREGS, plst->pid, (char *)&plst->regs, 0, NULL);
#else
    (void) plst;
#endif
    return 0;
}


/*
 *  Identify the current breakpoint. The process just stopped.
 */

    int
BreakIdentify (PID_LIST* plst, int adjust, int thread)
{
    int foreignBkpt = 0;
    int bidx;

    for (bidx = 1; bidx < (int) plst->break_alloc; bidx++) {
        int type = plst->break_list[bidx].type;

        if ((type == BRKT_INSTR || type == BRKT_STEPEMUL)
                &&  plst->regs.REG_PC - BREAK_ADJ
                == plst->break_list[bidx].ee_loc) {     /* found matching */
            if (!BreakThreadMatch (&plst->break_list[bidx], thread)) {
                if (foreignBkpt == 0) {
                    foreignBkpt = bidx;
                }
                continue;
            }
            if (adjust) {
                BreakAdjustPC (plst);
            }
            return bidx;
        }
    }
    if (foreignBkpt) {
        if (adjust) {
            BreakAdjustPC (plst);
        }
        return -foreignBkpt;
    }
    return 0;
}