xref: /csrg-svn/usr.bin/pascal/pdx/process/ptrace.c (revision 5507)

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)ptrace.c 1.1 01/18/82";

/*
 * routines for tracing the execution of a process
 *
 * The system call "ptrace" does all the work, these
 * routines just try to interface easily to it.
 */

#include "defs.h"
#include <signal.h>
#include <sys/param.h>
#include <sys/reg.h>
#include "process.h"
#include "object.h"
#include "process.rep"

#	if (isvaxpx)
#		include "pxinfo.h"
#	endif

/*
 * This magic macro enables us to look at the process' registers
 * in its user structure.  Very gross.
 */

#define regloc(reg)		(ctob(UPAGES) + ( sizeof(int) * (reg) ))

#define WMASK			(~(sizeof(WORD) - 1))
#define cachehash(addr)	((unsigned) ((addr >> 2) % CSIZE))

#define FIRSTSIG		SIGINT
#define LASTSIG			SIGQUIT
#define ischild(pid)	((pid) == 0)
#define traceme()		ptrace(0, 0, 0, 0)
#define setrep(n)		(1 << ((n)-1))
#define istraced(p)		(p->sigset&setrep(p->signo))

/*
 * ptrace options (specified in first argument)
 */

#define UREAD	3		/* read from process's user structure */
#define UWRITE	6		/* write to process's user structure */
#define IREAD	1		/* read from process's instruction space */
#define IWRITE	4		/* write to process's instruction space */
#define DREAD	2		/* read from process's data space */
#define DWRITE	5		/* write to process's data space */
#define CONT	7		/* continue stopped process */
#define SSTEP	9		/* continue for approximately one instruction */
#define PKILL	8		/* terminate the process */

/*
 * Start up a new process by forking and exec-ing the
 * given argument list, returning when the process is loaded
 * and ready to execute.  The PROCESS information (pointed to
 * by the first argument) is appropriately filled.
 *
 * If the given PROCESS structure is associated with an already running
 * process, we terminate it.
 */

/* VARARGS2 */
pstart(p, argv, infile, outfile)
PROCESS *p;
char **argv;
char *infile;
char *outfile;
{
	int status;
	FILE *in, *out;

	if (p->pid != 0) {					/* child already running? */
		ptrace(PKILL, p->pid, 0, 0);	/* ... kill it! */
	}
	psigtrace(p, SIGTRAP, TRUE);
	if ((p->pid = fork()) == -1) {
		panic("can't fork");
	}
	if (ischild(p->pid)) {
		traceme();
		if (infile != NIL) {
			if ((in = fopen(infile, "r")) == NIL) {
				printf("can't read %s\n", infile);
				exit(1);
			}
			fswap(0, fileno(in));
		}
		if (outfile != NIL) {
			if ((out = fopen(outfile, "w")) == NIL) {
				printf("can't write %s\n", outfile);
				exit(1);
			}
			fswap(1, fileno(out));
		}
		execvp(argv[0], argv);
		panic("can't exec %s", argv[0]);
	}
	pwait(p->pid, &status);
	getinfo(p, status);
	if (p->status != STOPPED) {
		error("program could not begin execution");
	}
}

/*
 * Continue a stopped process.  The argument points to a PROCESS structure.
 * Before the process is restarted it's user area is modified according to
 * the values in the structure.  When this routine finishes,
 * the structure has the new values from the process's user area.
 *
 * Pcont terminates when the process stops with a signal pending that
 * is being traced (via psigtrace), or when the process terminates.
 */

pcont(p)
PROCESS *p;
{
	int status;

	if (p->pid == 0) {
		error("program not active");
	}
	do {
		setinfo(p);
		sigs_off();
		if (ptrace(CONT, p->pid, p->pc, p->signo) < 0) {
			panic("can't continue process");
		}
		pwait(p->pid, &status);
		sigs_on();
		getinfo(p, status);
	} while (p->status == STOPPED && !istraced(p));
}

/*
 * single step as best ptrace can
 */

pstep(p)
PROCESS *p;
{
	int status;

	setinfo(p);
	sigs_off();
	ptrace(SSTEP, p->pid, p->pc, p->signo);
	pwait(p->pid, &status);
	sigs_on();
	getinfo(p, status);
}

/*
 * Return from execution when the given signal is pending.
 */

psigtrace(p, sig, sw)
PROCESS *p;
int sig;
int sw;
{
	if (sw) {
		p->sigset |= setrep(sig);
	} else {
		p->sigset &= ~setrep(sig);
	}
}

/*
 * Don't catch any signals.
 * Particularly useful when letting a process finish uninhibited (i.e. px).
 */

unsetsigtraces(p)
PROCESS *p;
{
	p->sigset = 0;
}

/*
 * turn off attention to signals not being caught
 */

typedef int INTFUNC();

LOCAL INTFUNC *sigfunc[NSIG];

LOCAL sigs_off()
{
	register int i;

	for (i = FIRSTSIG; i < LASTSIG; i++) {
		if (i != SIGKILL) {
			sigfunc[i] = signal(i, SIG_IGN);
		}
	}
}

/*
 * turn back on attention to signals
 */

LOCAL sigs_on()
{
	register int i;

	for (i = FIRSTSIG; i < LASTSIG; i++) {
		if (i != SIGKILL) {
			signal(i, sigfunc[i]);
		}
	}
}

/*
 * get PROCESS information from process's user area
 */

LOCAL int rloc[] ={
	R0, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11,
};

LOCAL getinfo(p, status)
register PROCESS *p;
register int status;
{
	register int i;

	p->signo = (status&0177);
	p->exitval = ((status >> 8)&0377);
	if (p->signo == STOPPED) {
		p->status = p->signo;
		p->signo = p->exitval;
		p->exitval = 0;
	} else {
		p->status = FINISHED;
		return;
	}
	for (i = 0; i < NREG; i++) {
		p->reg[i] = ptrace(UREAD, p->pid, regloc(rloc[i]), 0);
		p->oreg[i] = p->reg[i];
	}
	p->fp = p->ofp = ptrace(UREAD, p->pid, regloc(FP), 0);
	p->ap = p->oap = ptrace(UREAD, p->pid, regloc(AP), 0);
	p->sp = p->osp = ptrace(UREAD, p->pid, regloc(SP), 0);
	p->pc = p->opc = ptrace(UREAD, p->pid, regloc(PC), 0);
}

/*
 * set process's user area information from given PROCESS structure
 */

LOCAL setinfo(p)
register PROCESS *p;
{
	register int i;
	register int r;

	if (istraced(p)) {
		p->signo = 0;
	}
	for (i = 0; i < NREG; i++) {
		if ((r = p->reg[i]) != p->oreg[i]) {
			ptrace(UWRITE, p->pid, regloc(rloc[i]), r);
		}
	}
	if ((r = p->fp) != p->ofp) {
		ptrace(UWRITE, p->pid, regloc(FP), r);
	}
	if ((r = p->sp) != p->osp) {
		ptrace(UWRITE, p->pid, regloc(SP), r);
	}
	if ((r = p->ap) != p->oap) {
		ptrace(UWRITE, p->pid, regloc(AP), r);
	}
	if ((r = p->pc) != p->opc) {
		ptrace(UWRITE, p->pid, regloc(PC), r);
	}
}

/*
 * Structure for reading and writing by words, but dealing with bytes.
 */

typedef union {
	WORD pword;
	BYTE pbyte[sizeof(WORD)];
} PWORD;

/*
 * Read (write) from (to) the process' address space.
 * We must deal with ptrace's inability to look anywhere other
 * than at a word boundary.
 */

LOCAL WORD fetch();
LOCAL store();

pio(p, op, seg, buff, addr, nbytes)
PROCESS *p;
PIO_OP op;
PIO_SEG seg;
char *buff;
ADDRESS addr;
int nbytes;
{
	register int i;
	register ADDRESS newaddr;
	register char *cp;
	char *bufend;
	PWORD w;
	ADDRESS wordaddr;
	int byteoff;

	if (p->status != STOPPED) {
		error("program is not active");
	}
	cp = buff;
	newaddr = addr;
	wordaddr = (newaddr&WMASK);
	if (wordaddr != newaddr) {
		w.pword = fetch(p, seg, wordaddr);
		for (i = newaddr - wordaddr; i<sizeof(WORD) && nbytes>0; i++) {
			if (op == PREAD) {
				*cp++ = w.pbyte[i];
			} else {
				w.pbyte[i] = *cp++;
			}
			nbytes--;
		}
		if (op == PWRITE) {
			store(p, seg, wordaddr, w.pword);
		}
		newaddr = wordaddr + sizeof(WORD);
	}
	byteoff = (nbytes&(~WMASK));
	nbytes -= byteoff;
	bufend = cp + nbytes;
	while (cp < bufend) {
		if (op == PREAD) {
			*((WORD *) cp) = fetch(p, seg, newaddr);
		} else {
			store(p, seg, newaddr, *((WORD *) cp));
		}
		cp += sizeof(WORD);
		newaddr += sizeof(WORD);
	}
	if (byteoff > 0) {
		w.pword = fetch(p, seg, newaddr);
		for (i = 0; i < byteoff; i++) {
			if (op == PREAD) {
				*cp++ = w.pbyte[i];
			} else {
				w.pbyte[i] = *cp++;
			}
		}
		if (op == PWRITE) {
			store(p, seg, newaddr, w.pword);
		}
	}
}

/*
 * Get a word from a process at the given address.
 * The address is assumed to be on a word boundary.
 *
 * We use a simple cache scheme to avoid redundant references to
 * the instruction space (which is assumed to be pure).  In the
 * case of px, the "instruction" space lies between ENDOFF and
 * ENDOFF + objsize.
 *
 * It is necessary to use a write-through scheme so that
 * breakpoints right next to each other don't interfere.
 */

LOCAL WORD fetch(p, seg, addr)
PROCESS *p;
PIO_SEG seg;
register int addr;
{
	register CACHEWORD *wp;
	register WORD w;

	switch (seg) {
		case TEXTSEG:
#			if (isvaxpx)
				panic("tried to fetch from px i-space");
				/* NOTREACHED */
#			else
				wp = &p->word[cachehash(addr)];
				if (addr == 0 || wp->addr != addr) {
					w = ptrace(IREAD, p->pid, addr, 0);
					wp->addr = addr;
					wp->val = w;
				} else {
					w = wp->val;
				}
				break;
#			endif

		case DATASEG:
#			if (isvaxpx)
				if (addr >= ENDOFF && addr < ENDOFF + objsize) {
					wp = &p->word[cachehash(addr)];
					if (addr == 0 || wp->addr != addr) {
						w = ptrace(DREAD, p->pid, addr, 0);
						wp->addr = addr;
						wp->val = w;
					} else {
						w = wp->val;
					}
				} else {
					w = ptrace(DREAD, p->pid, addr, 0);
				}
#			else
				w = ptrace(DREAD, p->pid, addr, 0);
#			endif
			break;

		default:
			panic("fetch: bad seg %d", seg);
			/* NOTREACHED */
	}
	return(w);
}

/*
 * Put a word into the process' address space at the given address.
 * The address is assumed to be on a word boundary.
 */

LOCAL store(p, seg, addr, data)
PROCESS *p;
PIO_SEG seg;
int addr;
WORD data;
{
	register CACHEWORD *wp;

	switch (seg) {
		case TEXTSEG:
			wp = &p->word[cachehash(addr)];
			wp->addr = addr;
			wp->val = data;
			ptrace(IWRITE, p->pid, addr, data);
			break;

		case DATASEG:
#			if (isvaxpx)
				if (addr >= ENDOFF && addr < ENDOFF + objsize) {
					wp = &p->word[cachehash(addr)];
					wp->addr = addr;
					wp->val = data;
				}
#			endif
			ptrace(DWRITE, p->pid, addr, data);
			break;

		default:
			panic("store: bad seg %d", seg);
			/*NOTREACHED*/
	}
}

/*
 * Swap file numbers so as to redirect standard input and output.
 */

LOCAL fswap(oldfd, newfd)
int oldfd;
int newfd;
{
	if (oldfd != newfd) {
		close(oldfd);
		dup(newfd);
		close(newfd);
	}
}