runtime.c

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/*@(#)runtime.c	4.2  Ultrix  11/9/90*/

/************************************************************************
 *									*
 *			Copyright (c) 1986 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
 *									*
 *			Modification History				*
 *									*
 *  007 - fixed 'print function()' and "can't set a breakpoint in *
 *		  a function and do a 'print function(). also, fixed the  *
 *		   function return value to be correct.					  *
 *		  (L Miller, 25JAN90)									*
 *									*
 *  006	- Added support for vectors.							*
 *		  (L Miller, 18JAN90)									*
 *									*
 *	005 - Re-merged 4.3 changes to fix: a) dump of variables in	*
 *	      unnamed blocks was useless ("the mysterious $b" in 001;	*
 *	      b) $unsafecall wasn't there though it was documented.	*
 *	      (Jon Reeves, July 14, 1987)				*
 *									*
 *	004 - Merged in 4.3 changes.					*
 *	      (vjh, April 29, 1986)					*
 *									*
 *	003 - Fixed bug in down().  Added test for jsb routine when	*
 *	      determining the start address of a function in		*
 *	      findbeginning().						*
 *	      (vjh, August 14, 1985)					*
 *									*
 *	002 - Pushretval() now returns a boolean value.  Returns false	*
 *	      when value is inaccessible; used to panic.		*
 *	      (vjh, July 18, 1985)					*
 *									*
 *	001 - Fixed internal error - unexpected nil frame; occured when *
 *	      pc pointed to last instruction in main routine - 		*
 *	      getcurframe() was returning reg[PROGCTR]+1 as save_pc, 	*
 *	      which in this case is in hyper-space. Modified 		*
 *	      walkstack():  fixed dependencies on the above; removed	*
 *	      the mysterious $b# from stack traces.			*
 *	      (Victoria Holt, April 23, 1985)				*
 *									*
 ************************************************************************/

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
static char sccsid[] = "@(#)runtime.c	2.1	ULTRIX	4/24/89";
#endif not lint

/*
 * Runtime organization dependent routines, mostly dealing with
 * activation records.
 */

#include "defs.h"
#include "runtime.h"
#include "process.h"
#include "machine.h"
#include "events.h"
#include "mappings.h"
#include "main.h"
#include "symbols.h"
#include "tree.h"
#include "eval.h"
#include "operators.h"
#include "object.h"
#include <sys/param.h>
#include <sys/vm.h>

#ifndef public
typedef struct Frame *Frame;

#include "machine.h"
#endif

#define NSAVEREG 12

struct Frame {
    integer condition_handler;
    integer mask;
    Address save_ap;		/* argument pointer */
    Address save_fp;		/* frame pointer */
    Address save_pc;		/* program counter */
    Word save_reg[NSAVEREG];	/* not necessarily there */
};

private Frame curframe = nil;
private struct Frame curframerec;
private Boolean walkingstack = false;

#define frameeq(f1, f2) ((f1)->save_fp == (f2)->save_fp)

#define isstackaddr(addr) \
    (((addr) < 0x80000000) and ((addr) > USRSTACK))

typedef struct {
    Node callnode;
    Node cmdnode;
    boolean isfunc;
} CallEnv;

private CallEnv endproc;

/*
 * Set a frame to the current activation record.
 */

private getcurframe(frp)
Frame frp;
{
    register int i;

    checkref(frp);
    frp->mask = reg(NREG);
    frp->save_ap = reg(ARGP);
    frp->save_fp = reg(FRP);
    frp->save_pc = reg(PROGCTR);
    for (i = 0; i < NSAVEREG; i++) {
	frp->save_reg[i] = reg(i);
    }
}

/*
 * Get the saved registers from one frame to another
 * given mask specifying which registers were actually saved.
 */

#define bis(b, n) ((b & (1 << (n))) != 0)

private getsaveregs (newfrp, frp, mask)
Frame newfrp, frp;
integer mask;
{
    integer i, j;

    j = 0;
    for (i = 0; i < NSAVEREG; i++) {
	if (bis(mask, i)) {
	    newfrp->save_reg[i] = frp->save_reg[j];
	    ++j;
	}
    }
}

/*
 * Return a pointer to the next activation record up the stack.
 * Return nil if there is none.
 * Writes over space pointed to by given argument.
 */

private Frame nextframe(frp)
Frame frp;
{
    Frame newfrp;
    struct Frame frame;
    integer mask;
    Address prev_frame, callpc; 
    static integer ntramp = 0;

    newfrp = frp;
    prev_frame = frp->save_fp;

/*
 *  The check for interrupt generated frames is taken from adb with only
 *  partial understanding.  If you're in "sub" and on a sigxxx "sigsub"
 *  gets control, then the stack does NOT look like <main, sub, sigsub>.
 *
 *  As best I can make out it looks like:
 *
 *     <main, (machine check exception block + sub), sysframe, sigsub>.
 *
 *  When the signal occurs an exception block and a frame for the routine
 *  in which it occured are pushed on the user stack.  Then another frame
 *  is pushed corresponding to a call from the kernel to sigsub.
 *
 *  The addr in sub at which the exception occured is not in sub.save_pc
 *  but in the machine check exception block.  It is at the magic address
 *  fp + 84.
 *
 *  The current approach ignores the sys_frame (what adb reports as sigtramp)
 *  and takes the pc for sub from the exception block.  This allows the
 *  "where" command to report <main, sub, sigsub>, which seems reasonable.
 */

nextf:
    dread(&frame, prev_frame, sizeof(struct Frame));
    if (ntramp == 1) {
	dread(&callpc, prev_frame + 84, sizeof(callpc));
    } else {
	callpc = frame.save_pc;
    }
    if (frame.save_fp == nil or frame.save_pc == (Address) -1) {
	newfrp = nil;
    } else if (isstackaddr(callpc)) {
	ntramp++;
	prev_frame = frame.save_fp;
	goto nextf;
    } else {
	frame.save_pc = callpc;
        ntramp = 0;
	mask = ((frame.mask >> 16) & 0x0fff);
	getsaveregs(newfrp, &frame, mask);
	newfrp->condition_handler = frame.condition_handler;
	newfrp->mask = mask;
	newfrp->save_ap = frame.save_ap;
	newfrp->save_fp = frame.save_fp;
	newfrp->save_pc = frame.save_pc;
    }
    return newfrp;
}

/*
 * Get the current frame information in the given Frame and store the
 * associated function in the given value-result parameter.
 */

private getcurfunc (frp, fp)
Frame frp;
Symbol *fp;
{
    getcurframe(frp);
    *fp = whatblock(frp->save_pc);
}

/*
 * Return the frame associated with the next function up the call stack, or
 * nil if there is none.  The function is returned in a value-result parameter.
 * For "inline" functions the statically outer function and same frame
 * are returned.
 */

public Frame nextfunc (frp, fp)
Frame frp;
Symbol *fp;
{
    Symbol t;
    Frame nfrp;

    t = *fp;
    checkref(t);
    if (isinline(t)) {
	t = container(t);
	nfrp = frp;
    } else {
	nfrp = nextframe(frp);
	if (nfrp == nil) {
	    t = nil;
	} else {
	    t = whatblock(nfrp->save_pc);
	}
    }
    *fp = t;
    return nfrp;
}

/*
 * Return the frame associated with the given function.
 * If the function is nil, return the most recently activated frame.
 *
 * Static allocation for the frame.
 */

public Frame findframe(f)
Symbol f;
{
    Frame frp;
    static struct Frame frame;
    Symbol p;
    Boolean done;

    frp = &frame;
    getcurframe(frp);
    if (f != nil) {
	if (f == curfunc and curframe != nil) {
	    *frp = *curframe;
	} else {
	    done = false;
	    p = whatblock(frp->save_pc);
	    do {
		if (p == f) {
		    done = true;
		} else if (p == program) {
		    done = true;
		    frp = nil;
		} else {
		    frp = nextfunc(frp, &p);
		    if (frp == nil) {
			done = true;
		    }
		}
	    } while (not done);
	}
    }
    return frp;
}

/*
 * Set the registers according to the given frame pointer.
 */

public getnewregs (addr)
Address addr;
{
    struct Frame frame;
    integer i, j, mask;

    dread(&frame, addr, sizeof(frame));
    setreg(ARGP, frame.save_ap);
    setreg(FRP, frame.save_fp);
    setreg(PROGCTR, frame.save_pc);
    mask = ((frame.mask >> 16) & 0x0fff);
    j = 0;
    for (i = 0; i < NSAVEREG; i++) {
	if (bis(mask, i)) {
	    setreg(i, frame.save_reg[j]);
	    ++j;
	}
    }
    pc = frame.save_pc;
    setcurfunc(whatblock(pc));
}

/*
 * Find the return address of the current procedure/function.
 */

public Address return_addr()
{
    Frame frp;
    Address addr;
    struct Frame frame;

    frp = &frame;
    getcurframe(frp);
    frp = nextframe(frp);
    if (frp == nil) {
	addr = 0;
    } else {
	addr = frp->save_pc;
    }
    return addr;
}

/*
 * Push the value associated with the current function.
 */

public Boolean pushretval(len, isindirect)
Integer len;
Boolean isindirect;
{
    Word r0;
    Boolean success;

    r0 = reg(0);
    success = true;
    if (isindirect) {
	rpush((Address) r0, len);
    } else {
	switch (len) {
	    case sizeof(char):
		push(char, r0);
		break;

	    case sizeof(short):
		push(short, r0);
		break;

	    default:
		if (len == sizeof(Word)) {
		    push(Word, r0);
		} else if (len == 2*sizeof(Word)) {
		    push(Word, r0);
		    push(Word, reg(1));
		} else {
		    success = false;
		}
		break;
	}
    }
    return success;
}

/*
 * Return the base address for locals in the given frame.
 */

public Address locals_base(frp)
Frame frp;
{
    return (frp == nil) ? reg(FRP) : frp->save_fp;
}

/*
 * Return the base address for arguments in the given frame.
 */

public Address args_base(frp)
Frame frp;
{
    return (frp == nil) ? reg(ARGP) : frp->save_ap;
}

/*
 * Return saved register n from the given frame.
 */

public Word savereg(n, frp)
integer n;
Frame frp;
{
    Word w;

    if (frp == nil) {
	w = reg(n);
    } else {
	switch (n) {
	    case ARGP:
		w = frp->save_ap;
		break;

	    case FRP:
		w = frp->save_fp;
		break;

	    case STKP:
		w = reg(STKP);
		break;

	    case PROGCTR:
		w = frp->save_pc;
		break;

	    default:
		assert(n >= 0 and n < NSAVEREG);
		w = frp->save_reg[n];
		break;
	}
    }
    return w;
}

/*
 * Return the nth argument to the current procedure.
 */

public Word argn(n, frp)
integer n;
Frame frp;
{
    Word w;

    dread(&w, args_base(frp) + (n * sizeof(Word)), sizeof(w));
    return w;
}

/*
 * Print a list of currently active blocks starting with most recent.
 */

public wherecmd()
{
    walkstack(false);
}

/*
 * Print the variables in the given frame or the current one if nil.
 */

public dump (func)
Symbol func;
{
    Symbol f;
    Frame frp;

    if (func == nil) {
	f = curfunc;
	if (curframe != nil) {
	    frp = curframe;
	} else {
	    frp = findframe(f);
	}
    } else {
	f = func;
	frp = findframe(f);
    }
    showaggrs = true;
    printcallinfo(f, frp);
    dumpvars(f, frp);
}

/*
 * Dump all values.
 */

public dumpall ()
{
    walkstack(true);
}

/*
 * Walk the stack of active procedures printing information
 * about each active procedure.
 */

private walkstack(dumpvariables)
Boolean dumpvariables;
{
    Frame frp;
    boolean save;
    Symbol f;
    struct Frame frame;

    if (notstarted(process) or isfinished(process)) {
	error("program is not active");
    } else {
	save = walkingstack;
	walkingstack = true;
	showaggrs = dumpvariables;
	frp = &frame;
	getcurfunc(frp, &f);
	if(!never_run) {
		for (;;) {
	    	printcallinfo(f, frp);
	    	if (dumpvariables) {
				dumpvars(f, frp);
				putchar('\n');
	    	}
	    	frp = nextfunc(frp, &f);
	    	if (frp == nil or f == program) {
				break;
	    	}
		}
	}
	if (dumpvariables) {
	    printf("in \"%s\":\n", symname(program));
	    dumpvars(program, nil);
	    putchar('\n');
	}
	walkingstack = save;
    }
}

/*
 * Print out the information about a call, i.e.,
 * routine name, parameter values, and source location.
 */

private printcallinfo (f, frp)
Symbol f;
Frame frp;
{
    Lineno line;
    Address savepc;

    savepc = frp->save_pc;
    if (frp->save_fp != reg(FRP)) {
	savepc -= 1;
    }
    printname(stdout, f);
    if (not isinline(f)) {
	printparams(f, frp);
    }
    line = srcline(savepc);
    if (line != 0) {
	printf(", line %d", line);
	printf(" in \"%s\"\n", srcfilename(savepc));
    } else {
	printf(" at 0x%x\n", savepc);
    }
}

/*
 * Set the current function to the given symbol.
 * We must adjust "curframe" so that subsequent operations are
 * not confused; for simplicity we simply clear it.
 */

public setcurfunc (f)
Symbol f;
{
    curfunc = f;
    curframe = nil;
}

/*
 * Return the frame for the current function.
 * The space for the frame is allocated statically.
 */