pcontrol.c

Sun Solaris 10 中的 DTrace 组件的源代码。请参看: http://www.sun.com/software/solaris/observability.jsp

					errstr = "Pstopstatus PCDSTOP"; break;
				case PCWSTOP:
					errstr = "Pstopstatus PCWSTOP"; break;
				default:
					errstr = "Pstopstatus PC???"; break;
				}
				dprintf("%s: %s\n", errstr, strerror(err));
			}
			deadcheck(P);
			break;
		}
		if (err != EINTR && err != ERESTART) {
			errno = err;
			return (-1);
		}
	}

	if (!(P->status.pr_flags & PR_STOPPED)) {
		P->state = PS_RUN;
		if (request == PCNULL || request == PCDSTOP || msec != 0)
			return (0);
		dprintf("Pstopstatus: process is not stopped\n");
		errno = EPROTO;
		return (-1);
	}

	P->state = PS_STOP;

	if (_libproc_debug)	/* debugging */
		prdump(P);

	/*
	 * If the process was already stopped coming into Pstopstatus(),
	 * then don't use its PC to set P->sysaddr since it may have been
	 * changed since the time the process originally stopped.
	 */
	if (old_state == PS_STOP)
		return (0);

	switch (P->status.pr_lwp.pr_why) {
	case PR_SYSENTRY:
	case PR_SYSEXIT:
		if (Pissyscall_prev(P, P->status.pr_lwp.pr_reg[R_PC],
		    &P->sysaddr) == 0)
			P->sysaddr = P->status.pr_lwp.pr_reg[R_PC];
		break;
	case PR_REQUESTED:
	case PR_SIGNALLED:
	case PR_FAULTED:
	case PR_JOBCONTROL:
	case PR_SUSPENDED:
		break;
	default:
		errno = EPROTO;
		return (-1);
	}

	return (0);
}

/*
 * Wait for the process to stop for any reason.
 */
int
Pwait(struct ps_prochandle *P, uint_t msec)
{
	return (Pstopstatus(P, PCWSTOP, msec));
}

/*
 * Direct the process to stop; wait for it to stop.
 */
int
Pstop(struct ps_prochandle *P, uint_t msec)
{
	return (Pstopstatus(P, PCSTOP, msec));
}

/*
 * Direct the process to stop; don't wait.
 */
int
Pdstop(struct ps_prochandle *P)
{
	return (Pstopstatus(P, PCDSTOP, 0));
}

static void
deadcheck(struct ps_prochandle *P)
{
	int fd;
	void *buf;
	size_t size;

	if (P->statfd < 0)
		P->state = PS_UNDEAD;
	else {
		if (P->agentstatfd < 0) {
			fd = P->statfd;
			buf = &P->status;
			size = sizeof (P->status);
		} else {
			fd = P->agentstatfd;
			buf = &P->status.pr_lwp;
			size = sizeof (P->status.pr_lwp);
		}
		while (pread(fd, buf, size, (off_t)0) != size) {
			switch (errno) {
			default:
				P->state = PS_UNDEAD;
				break;
			case EINTR:
			case ERESTART:
				continue;
			case EAGAIN:
				P->state = PS_LOST;
				break;
			}
			break;
		}
		P->status.pr_flags = P->status.pr_lwp.pr_flags;
	}
}

/*
 * Get the value of one register from stopped process.
 */
int
Pgetareg(struct ps_prochandle *P, int regno, prgreg_t *preg)
{
	if (regno < 0 || regno >= NPRGREG) {
		errno = EINVAL;
		return (-1);
	}

	if (P->state == PS_IDLE) {
		errno = ENODATA;
		return (-1);
	}

	if (P->state != PS_STOP && P->state != PS_DEAD) {
		errno = EBUSY;
		return (-1);
	}

	*preg = P->status.pr_lwp.pr_reg[regno];
	return (0);
}

/*
 * Put value of one register into stopped process.
 */
int
Pputareg(struct ps_prochandle *P, int regno, prgreg_t reg)
{
	if (regno < 0 || regno >= NPRGREG) {
		errno = EINVAL;
		return (-1);
	}

	if (P->state != PS_STOP) {
		errno = EBUSY;
		return (-1);
	}

	P->status.pr_lwp.pr_reg[regno] = reg;
	P->flags |= SETREGS;	/* set registers before continuing */
	return (0);
}

int
Psetrun(struct ps_prochandle *P,
	int sig,	/* signal to pass to process */
	int flags)	/* PRSTEP|PRSABORT|PRSTOP|PRCSIG|PRCFAULT */
{
	int ctlfd = (P->agentctlfd >= 0) ? P->agentctlfd : P->ctlfd;
	int sbits = (PR_DSTOP | PR_ISTOP | PR_ASLEEP);

	long ctl[1 +					/* PCCFAULT	*/
		1 + sizeof (siginfo_t)/sizeof (long) +	/* PCSSIG/PCCSIG */
		2 ];					/* PCRUN	*/

	long *ctlp = ctl;
	size_t size;

	if (P->state != PS_STOP && (P->status.pr_lwp.pr_flags & sbits) == 0) {
		errno = EBUSY;
		return (-1);
	}

	Psync(P);	/* flush tracing flags and registers */

	if (flags & PRCFAULT) {		/* clear current fault */
		*ctlp++ = PCCFAULT;
		flags &= ~PRCFAULT;
	}

	if (flags & PRCSIG) {		/* clear current signal */
		*ctlp++ = PCCSIG;
		flags &= ~PRCSIG;
	} else if (sig && sig != P->status.pr_lwp.pr_cursig) {
		/* make current signal */
		siginfo_t *infop;

		*ctlp++ = PCSSIG;
		infop = (siginfo_t *)ctlp;
		(void) memset(infop, 0, sizeof (*infop));
		infop->si_signo = sig;
		ctlp += sizeof (siginfo_t) / sizeof (long);
	}

	*ctlp++ = PCRUN;
	*ctlp++ = flags;
	size = (char *)ctlp - (char *)ctl;

	P->info_valid = 0;	/* will need to update map and file info */

	/*
	 * If we've cached ucontext-list information while we were stopped,
	 * free it now.
	 */
	if (P->ucaddrs != NULL) {
		free(P->ucaddrs);
		P->ucaddrs = NULL;
		P->ucnelems = 0;
	}

	if (write(ctlfd, ctl, size) != size) {
		/* If it is dead or lost, return the real status, not PS_RUN */
		if (errno == ENOENT || errno == EAGAIN) {
			(void) Pstopstatus(P, PCNULL, 0);
			return (0);
		}
		/* If it is not in a jobcontrol stop, issue an error message */
		if (errno != EBUSY ||
		    P->status.pr_lwp.pr_why != PR_JOBCONTROL) {
			dprintf("Psetrun: %s\n", strerror(errno));
			return (-1);
		}
		/* Otherwise pretend that the job-stopped process is running */
	}

	P->state = PS_RUN;
	return (0);
}

ssize_t
Pread(struct ps_prochandle *P,
	void *buf,		/* caller's buffer */
	size_t nbyte,		/* number of bytes to read */
	uintptr_t address)	/* address in process */
{
	return (P->ops->p_pread(P, buf, nbyte, address));
}

ssize_t
Pread_string(struct ps_prochandle *P,
	char *buf, 		/* caller's buffer */
	size_t size,		/* upper limit on bytes to read */
	uintptr_t addr)		/* address in process */
{
	enum { STRSZ = 40 };
	char string[STRSZ + 1];
	ssize_t leng = 0;
	int nbyte;

	if (size < 2) {
		errno = EINVAL;
		return (-1);
	}

	size--;			/* ensure trailing null fits in buffer */

	*buf = '\0';
	string[STRSZ] = '\0';

	for (nbyte = STRSZ; nbyte == STRSZ && leng < size; addr += STRSZ) {
		if ((nbyte = P->ops->p_pread(P, string, STRSZ, addr)) <= 0) {
			buf[leng] = '\0';
			return (leng ? leng : -1);
		}
		if ((nbyte = strlen(string)) > 0) {
			if (leng + nbyte > size)
				nbyte = size - leng;
			(void) strncpy(buf + leng, string, nbyte);
			leng += nbyte;
		}
	}
	buf[leng] = '\0';
	return (leng);
}

ssize_t
Pwrite(struct ps_prochandle *P,
	const void *buf,	/* caller's buffer */
	size_t nbyte,		/* number of bytes to write */
	uintptr_t address)	/* address in process */
{
	return (P->ops->p_pwrite(P, buf, nbyte, address));
}

int
Pclearsig(struct ps_prochandle *P)
{
	int ctlfd = (P->agentctlfd >= 0)? P->agentctlfd : P->ctlfd;
	long ctl = PCCSIG;

	if (write(ctlfd, &ctl, sizeof (ctl)) != sizeof (ctl))
		return (-1);
	P->status.pr_lwp.pr_cursig = 0;
	return (0);
}

int
Pclearfault(struct ps_prochandle *P)
{
	int ctlfd = (P->agentctlfd >= 0)? P->agentctlfd : P->ctlfd;
	long ctl = PCCFAULT;

	if (write(ctlfd, &ctl, sizeof (ctl)) != sizeof (ctl))
		return (-1);
	return (0);
}

/*
 * Set a breakpoint trap, return original instruction.
 */
int
Psetbkpt(struct ps_prochandle *P, uintptr_t address, ulong_t *saved)
{
	long ctl[1 + sizeof (priovec_t) / sizeof (long) +	/* PCREAD */
		1 + sizeof (priovec_t) / sizeof (long)];	/* PCWRITE */
	long *ctlp = ctl;
	size_t size;
	priovec_t *iovp;
	instr_t bpt = BPT;
	instr_t old;

	if (P->state == PS_DEAD || P->state == PS_UNDEAD ||
	    P->state == PS_IDLE) {
		errno = ENOENT;
		return (-1);
	}

	/* fetch the old instruction */
	*ctlp++ = PCREAD;
	iovp = (priovec_t *)ctlp;
	iovp->pio_base = &old;
	iovp->pio_len = sizeof (old);
	iovp->pio_offset = address;
	ctlp += sizeof (priovec_t) / sizeof (long);

	/* write the BPT instruction */
	*ctlp++ = PCWRITE;
	iovp = (priovec_t *)ctlp;
	iovp->pio_base = &bpt;
	iovp->pio_len = sizeof (bpt);
	iovp->pio_offset = address;
	ctlp += sizeof (priovec_t) / sizeof (long);

	size = (char *)ctlp - (char *)ctl;
	if (write(P->ctlfd, ctl, size) != size)
		return (-1);

	/*
	 * Fail if there was already a breakpoint there from another debugger
	 * or DTrace's user-level tracing on x86.
	 */
	if (old == BPT)
		return (EBUSY);

	*saved = (ulong_t)old;
	return (0);
}

/*
 * Restore original instruction where a breakpoint was set.
 */
int
Pdelbkpt(struct ps_prochandle *P, uintptr_t address, ulong_t saved)
{
	instr_t old = (instr_t)saved;
	instr_t cur;

	if (P->state == PS_DEAD || P->state == PS_UNDEAD ||
	    P->state == PS_IDLE) {
		errno = ENOENT;
		return (-1);
	}

	/*
	 * If the breakpoint instruction we had placed has been overwritten
	 * with a new instruction, then don't try to replace it with the
	 * old instruction. Doing do can cause problems with self-modifying
	 * code -- PLTs for example. If the Pread() fails, we assume that we
	 * should proceed though most likely the Pwrite() will also fail.
	 */
	if (Pread(P, &cur, sizeof (cur), address) == sizeof (cur) &&
	    cur != BPT)
		return (0);

	if (Pwrite(P, &old, sizeof (old), address) != sizeof (old))
		return (-1);

	return (0);
}

/*
 * Common code for Pxecbkpt() and Lxecbkpt().
 * Develop the array of requests that will do the job, then
 * write them to the specified control file descriptor.
 * Return the non-zero errno if the write fails.
 */
static int
execute_bkpt(
	int ctlfd,		/* process or LWP control file descriptor */
	const fltset_t *faultset,	/* current set of traced faults */
	const sigset_t *sigmask,	/* current signal mask */
	uintptr_t address,		/* address of breakpint */
	ulong_t saved)			/* the saved instruction */
{
	long ctl[
		1 + sizeof (sigset_t) / sizeof (long) +		/* PCSHOLD */
		1 + sizeof (fltset_t) / sizeof (long) +		/* PCSFAULT */
		1 + sizeof (priovec_t) / sizeof (long) +	/* PCWRITE */
		2 +						/* PCRUN */
		1 +						/* PCWSTOP */
		1 +						/* PCCFAULT */
		1 + sizeof (priovec_t) / sizeof (long) +	/* PCWRITE */
		1 + sizeof (fltset_t) / sizeof (long) +		/* PCSFAULT */
		1 + sizeof (sigset_t) / sizeof (long)];		/* PCSHOLD */
	long *ctlp = ctl;
	sigset_t unblock;
	size_t size;
	ssize_t ssize;
	priovec_t *iovp;
	sigset_t *holdp;
	fltset_t *faultp;
	instr_t old = (instr_t)saved;
	instr_t bpt = BPT;
	int error = 0;

	/* block our signals for the duration */
	(void) sigprocmask(SIG_BLOCK, &blockable_sigs, &unblock);

	/* hold posted signals */
	*ctlp++ = PCSHOLD;
	holdp = (sigset_t *)ctlp;
	prfillset(holdp);
	prdelset(holdp, SIGKILL);
	prdelset(holdp, SIGSTOP);
	ctlp += sizeof (sigset_t) / sizeof (long);

	/* force tracing of FLTTRACE */
	if (!(prismember(faultset, FLTTRACE))) {
		*ctlp++ = PCSFAULT;
		faultp = (fltset_t *)ctlp;
		*faultp = *faultset;
		praddset(faultp, FLTTRACE);
		ctlp += sizeof (fltset_t) / sizeof (long);
	}

	/* restore the old instruction */
	*ctlp++ = PCWRITE;
	iovp = (priovec_t *)ctlp;
	iovp->pio_base = &old;
	iovp->pio_len = sizeof (old);
	iovp->pio_offset = address;
	ctlp += sizeof (priovec_t) / sizeof (long);

	/* clear current signal and fault; set running w/ single-step */
	*ctlp++ = PCRUN;
	*ctlp++ = PRCSIG | PRCFAULT | PRSTEP;

	/* wait for stop, cancel the fault */
	*ctlp++ = PCWSTOP;
	*ctlp++ = PCCFAULT;

	/* restore the breakpoint trap */
	*ctlp++ = PCWRITE;
	iovp = (priovec_t *)ctlp;
	iovp->pio_base = &bpt;
	iovp->pio_len = sizeof (bpt);
	iovp->pio_offset = address;
	ctlp += sizeof (priovec_t) / sizeof (long);

	/* restore fault tracing set */
	if (!(prismember(faultset, FLTTRACE))) {
		*ctlp++ = PCSFAULT;
		*(fltset_t *)ctlp = *faultset;
		ctlp += sizeof (fltset_t) / sizeof (long);
	}

	/* restore the hold mask */
	*ctlp++ = PCSHOLD;
	*(sigset_t *)ctlp = *sigmask;
	ctlp += sizeof (sigset_t) / sizeof (long);

	size = (char *)ctlp - (char *)ctl;
	if ((ssize = write(ctlfd, ctl, size)) != size)
		error = (ssize == -1)? errno : EINTR;
	(void) sigprocmask(SIG_SETMASK, &unblock, NULL);
	return (error);
}

/*
 * Step over a breakpoint, i.e., execute the instruction that
 * really belongs at the breakpoint location (the current %pc)
 * and leave the process stopped at the next instruction.
 */
int
Pxecbkpt(struct ps_prochandle *P, ulong_t saved)
{
	int ctlfd = (P->agentctlfd >= 0)? P->agentctlfd : P->ctlfd;
	int rv, error;

	if (P->state != PS_STOP) {
		errno = EBUSY;
		return (-1);
	}

	Psync(P);

	error = execute_bkpt(ctlfd,
		&P->status.pr_flttrace, &P->status.pr_lwp.pr_lwphold,
		P->status.pr_lwp.pr_reg[R_PC], saved);
	rv = Pstopstatus(P, PCNULL, 0);

	if (error != 0) {
		if (P->status.pr_lwp.pr_why == PR_JOBCONTROL &&
		    error == EBUSY) {	/* jobcontrol stop -- back off */
			P->state = PS_RUN;
			return (0);
		}
		if (error == ENOENT)
			return (0);
		errno = error;
		return (-1);
	}

	return (rv);
}

/*
 * Install the watchpoint described by wp.
 */
int
Psetwapt(struct ps_prochandle *P, const prwatch_t *wp)
{
	long ctl[1 + sizeof (prwatch_t) / sizeof (long)];
	prwatch_t *cwp = (prwatch_t *)&ctl[1];

	if (P->state == PS_DEAD || P->state == PS_UNDEAD ||
	    P->state == PS_IDLE) {
		errno = ENOENT;
		return (-1);
	}

	ctl[0] = PCWATCH;