trap.c

早期freebsd实现

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1992 OMRON Corporation.
 * Copyright (c) 1982, 1986, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * from: Utah $Hdr: trap.c 1.35 91/12/26$
 * from: hp300/hp300/trap.c	8.4 (Berkeley) 9/23/93
 *
 *	@(#)trap.c	8.5 (Berkeley) 12/6/93
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/acct.h>
#include <sys/kernel.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/syscall.h>
#include <sys/syslog.h>
#include <sys/user.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <machine/psl.h>
#include <machine/trap.h>
#include <machine/cpu.h>
#include <machine/reg.h>
#include <machine/mtpr.h>

#include <vm/vm.h>
#include <vm/pmap.h>

struct	sysent	sysent[];
int	nsysent;

char	*trap_type[] = {
	"Bus error",
	"Address error",
	"Illegal instruction",
	"Zero divide",
	"CHK instruction",
	"TRAPV instruction",
	"Privilege violation",
	"Trace trap",
	"MMU fault",
	"SSIR trap",
	"Format error",
	"68881 exception",
	"Coprocessor violation",
	"Async system trap"
};
#define	TRAP_TYPES	(sizeof trap_type / sizeof trap_type[0])

/*
 * Size of various exception stack frames (minus the standard 8 bytes)
 */
short	exframesize[] = {
	FMT0SIZE,	/* type 0 - normal (68020/030/040) */
	FMT1SIZE,	/* type 1 - throwaway (68020/030/040) */
	FMT2SIZE,	/* type 2 - normal 6-word (68020/030/040) */
	FMT3SIZE,	/* type 3 - FP post-instruction (68040) */
	-1, -1, -1,	/* type 4-6 - undefined */
	FMT7SIZE,	/* type 7 - access error (68040) */
	58,		/* type 8 - bus fault (68010) */
	FMT9SIZE,	/* type 9 - coprocessor mid-instruction (68020/030) */
	FMTASIZE,	/* type A - short bus fault (68020/030) */
	FMTBSIZE,	/* type B - long bus fault (68020/030) */
	-1, -1, -1, -1	/* type C-F - undefined */
};

#ifdef LUNA2
#define KDFAULT(c)	(mmutype == MMU_68040 ? \
			    ((c) & SSW4_TMMASK) == SSW4_TMKD : \
			    ((c) & (SSW_DF|FC_SUPERD)) == (SSW_DF|FC_SUPERD))
#define WRFAULT(c) 	(mmutype == MMU_68040 ? \
			    ((c) & SSW4_RW) == 0 : \
			    ((c) & (SSW_DF|SSW_RW)) == SSW_DF)
#else
#define KDFAULT(c)	(((c) & (SSW_DF|SSW_FCMASK)) == (SSW_DF|FC_SUPERD))
#define WRFAULT(c)	(((c) & (SSW_DF|SSW_RW)) == SSW_DF)
#endif

#ifdef DEBUG
int mmudebug = 0;
int mmupid = -1;
#define MDB_FOLLOW	1
#define MDB_WBFOLLOW	2
#define MDB_WBFAILED	4
#define MDB_ISPID(p)	(p) == mmupid
#endif

/*
 * trap and syscall both need the following work done before returning
 * to user mode.
 */
static inline void
userret(p, fp, oticks, faultaddr, fromtrap)
	register struct proc *p;
	register struct frame *fp;
	u_quad_t oticks;
	u_int faultaddr;
	int fromtrap;
{
	int sig, s;
#ifdef LUNA2
	int beenhere = 0;

again:
#endif
	/* take pending signals */
	while ((sig = CURSIG(p)) != 0)
		postsig(sig);
	p->p_priority = p->p_usrpri;
	if (want_resched) {
		/*
		 * Since we are curproc, clock will normally just change
		 * our priority without moving us from one queue to another
		 * (since the running process is not on a queue.)
		 * If that happened after we put ourselves on the run queue
		 * but before we switched, we might not be on the queue
		 * indicated by our priority.
		 */
		s = splstatclock();
		setrunqueue(p);
		p->p_stats->p_ru.ru_nivcsw++;
		mi_switch();
		splx(s);
		while ((sig = CURSIG(p)) != 0)
			postsig(sig);
	}

	/*
	 * If profiling, charge system time to the trapped pc.
	 */
	if (p->p_flag & P_PROFIL) {
		extern int psratio;

		addupc_task(p, fp->f_pc,
			    (int)(p->p_sticks - oticks) * psratio);
	}
#ifdef LUNA2
	/*
	 * Deal with user mode writebacks (from trap, or from sigreturn).
	 * If any writeback fails, go back and attempt signal delivery.
	 * unless we have already been here and attempted the writeback
	 * (e.g. bad address with user ignoring SIGSEGV).  In that case
	 * we just return to the user without sucessfully completing
	 * the writebacks.  Maybe we should just drop the sucker?
	 */
	if (mmutype == MMU_68040 && fp->f_format == FMT7) {
		if (beenhere) {
#ifdef DEBUG
			if (mmudebug & MDB_WBFAILED)
				printf(fromtrap ?
		"pid %d(%s): writeback aborted, pc=%x, fa=%x\n" :
		"pid %d(%s): writeback aborted in sigreturn, pc=%x\n",
				    p->p_pid, p->p_comm, fp->f_pc, faultaddr);
#endif
		} else if (sig = writeback(fp, fromtrap)) {
			beenhere = 1;
			oticks = p->p_sticks;
			trapsignal(p, sig, faultaddr);
			goto again;
		}
	}
#endif
	curpriority = p->p_priority;
}

/*
 * Trap is called from locore to handle most types of processor traps,
 * including events such as simulated software interrupts/AST's.
 * System calls are broken out for efficiency.
 */
/*ARGSUSED*/
trap(type, code, v, frame)
	int type;
	unsigned code;
	register unsigned v;
	struct frame frame;
{
	register int i;
	unsigned ucode;
	register struct proc *p;
	u_quad_t sticks;
	unsigned ncode;
	extern char fswintr[];

	cnt.v_trap++;
	p = curproc;
	ucode = 0;
	if (USERMODE(frame.f_sr)) {
		type |= T_USER;
		sticks = p->p_sticks;
		p->p_md.md_regs = frame.f_regs;
	}
	switch (type) {

	default:
dopanic:
		printf("trap type %d, code = %x, v = %x\n", type, code, v);
		regdump(&frame, 128);
		type &= ~T_USER;
		if ((unsigned)type < TRAP_TYPES)
			panic(trap_type[type]);
		panic("trap");

	case T_BUSERR:		/* kernel bus error */
		if (!p->p_addr->u_pcb.pcb_onfault)
			goto dopanic;
		/*
		 * If we have arranged to catch this fault in any of the
		 * copy to/from user space routines, set PC to return to
		 * indicated location and set flag informing buserror code
		 * that it may need to clean up stack frame.
		 */
copyfault:
		frame.f_stackadj = exframesize[frame.f_format];
		frame.f_format = frame.f_vector = 0;
		frame.f_pc = (int) p->p_addr->u_pcb.pcb_onfault;
		return;

	case T_BUSERR|T_USER:	/* bus error */
	case T_ADDRERR|T_USER:	/* address error */
		ucode = v;
		i = SIGBUS;
		break;

#ifdef FPCOPROC
	case T_COPERR:		/* kernel coprocessor violation */
#endif
	case T_FMTERR|T_USER:	/* do all RTE errors come in as T_USER? */
	case T_FMTERR:		/* ...just in case... */
	/*
	 * The user has most likely trashed the RTE or FP state info
	 * in the stack frame of a signal handler.
	 */
		type |= T_USER;
		printf("pid %d: kernel %s exception\n", p->p_pid,
		       type==T_COPERR ? "coprocessor" : "format");
		p->p_sigacts->ps_sigact[SIGILL] = SIG_DFL;
		i = sigmask(SIGILL);
		p->p_sigignore &= ~i;
		p->p_sigcatch &= ~i;
		p->p_sigmask &= ~i;
		i = SIGILL;
		ucode = frame.f_format;	/* XXX was ILL_RESAD_FAULT */
		break;

#ifdef FPCOPROC
	case T_COPERR|T_USER:	/* user coprocessor violation */
	/* What is a proper response here? */
		ucode = 0;
		i = SIGFPE;
		break;

	case T_FPERR|T_USER:	/* 68881 exceptions */
	/*
	 * We pass along the 68881 status register which locore stashed
	 * in code for us.  Note that there is a possibility that the
	 * bit pattern of this register will conflict with one of the
	 * FPE_* codes defined in signal.h.  Fortunately for us, the
	 * only such codes we use are all in the range 1-7 and the low
	 * 3 bits of the status register are defined as 0 so there is
	 * no clash.
	 */
		ucode = code;
		i = SIGFPE;
		break;
#endif

#ifdef LUNA2
	case T_FPEMULI|T_USER:	/* unimplemented FP instuction */
	case T_FPEMULD|T_USER:	/* unimplemented FP data type */
		/* XXX need to FSAVE */
		printf("pid %d(%s): unimplemented FP %s at %x (EA %x)\n",
		       p->p_pid, p->p_comm,
		       frame.f_format == 2 ? "instruction" : "data type",
		       frame.f_pc, frame.f_fmt2.f_iaddr);
		/* XXX need to FRESTORE */
		i = SIGFPE;
		break;
#endif

	case T_ILLINST|T_USER:	/* illegal instruction fault */
	case T_PRIVINST|T_USER:	/* privileged instruction fault */
		ucode = frame.f_format;	/* XXX was ILL_PRIVIN_FAULT */
		i = SIGILL;
		break;

	case T_ZERODIV|T_USER:	/* Divide by zero */
		ucode = frame.f_format;	/* XXX was FPE_INTDIV_TRAP */
		i = SIGFPE;
		break;

	case T_CHKINST|T_USER:	/* CHK instruction trap */
		ucode = frame.f_format;	/* XXX was FPE_SUBRNG_TRAP */
		i = SIGFPE;
		break;

	case T_TRAPVINST|T_USER:	/* TRAPV instruction trap */
		ucode = frame.f_format;	/* XXX was FPE_INTOVF_TRAP */
		i = SIGFPE;
		break;

	/*
	 * XXX: Trace traps are a nightmare.
	 *
	 *	HP-UX uses trap #1 for breakpoints,
	 *	HPBSD uses trap #2,
	 *	SUN 3.x uses trap #15,
	 *	KGDB uses trap #15 (for kernel breakpoints; handled elsewhere).
	 *
	 * HPBSD and HP-UX traps both get mapped by locore.s into T_TRACE.
	 * SUN 3.x traps get passed through as T_TRAP15 and are not really
	 * supported yet.
	 */
	case T_TRACE:		/* kernel trace trap */
	case T_TRAP15:		/* SUN trace trap */
		frame.f_sr &= ~PSL_T;
		i = SIGTRAP;
		break;

	case T_TRACE|T_USER:	/* user trace trap */
	case T_TRAP15|T_USER:	/* SUN user trace trap */
		frame.f_sr &= ~PSL_T;
		i = SIGTRAP;
		break;

	case T_ASTFLT:		/* system async trap, cannot happen */
		goto dopanic;

	case T_ASTFLT|T_USER:	/* user async trap */
		astpending = 0;
		/*
		 * We check for software interrupts first.  This is because
		 * they are at a higher level than ASTs, and on a VAX would
		 * interrupt the AST.  We assume that if we are processing
		 * an AST that we must be at IPL0 so we don't bother to
		 * check.  Note that we ensure that we are at least at SIR
		 * IPL while processing the SIR.
		 */
		spl1();
		/* fall into... */

	case T_SSIR:		/* software interrupt */
	case T_SSIR|T_USER:
		if (ssir & SIR_NET) {
			siroff(SIR_NET);
			cnt.v_soft++;
			netintr();
		}
		if (ssir & SIR_CLOCK) {
			siroff(SIR_CLOCK);
			cnt.v_soft++;
			softclock();
		}
		/*
		 * If this was not an AST trap, we are all done.
		 */
		if (type != (T_ASTFLT|T_USER)) {
			cnt.v_trap--;
			return;
		}
		spl0();
		if (p->p_flag & P_OWEUPC) {
			p->p_flag &= ~P_OWEUPC;
			ADDUPROF(p);
		}
		goto out;

	case T_MMUFLT:		/* kernel mode page fault */
		/*
		 * If we were doing profiling ticks or other user mode
		 * stuff from interrupt code, Just Say No.
		 */
		if (p->p_addr->u_pcb.pcb_onfault == fswintr)
			goto copyfault;
		/* fall into ... */

	case T_MMUFLT|T_USER:	/* page fault */
	    {
		register vm_offset_t va;
		register struct vmspace *vm = p->p_vmspace;
		register vm_map_t map;
		int rv;
		vm_prot_t ftype;
		extern vm_map_t kernel_map;

#ifdef DEBUG
		if ((mmudebug & MDB_WBFOLLOW) || MDB_ISPID(p->p_pid))
		printf("trap: T_MMUFLT pid=%d, code=%x, v=%x, pc=%x, sr=%x\n",
		       p->p_pid, code, v, frame.f_pc, frame.f_sr);
#endif
		/*
		 * It is only a kernel address space fault iff:
		 * 	1. (type & T_USER) == 0  and
		 * 	2. pcb_onfault not set or
		 *	3. pcb_onfault set but supervisor space data fault
		 * The last can occur during an exec() copyin where the
		 * argument space is lazy-allocated.
		 */
		if (type == T_MMUFLT &&
		    (!p->p_addr->u_pcb.pcb_onfault || KDFAULT(code)))
			map = kernel_map;
		else
			map = &vm->vm_map;
		if (WRFAULT(code))
			ftype = VM_PROT_READ | VM_PROT_WRITE;
		else
			ftype = VM_PROT_READ;
		va = trunc_page((vm_offset_t)v);
#ifdef DEBUG
		if (map == kernel_map && va == 0) {
			printf("trap: bad kernel access at %x\n", v);
			goto dopanic;
		}
#endif
		rv = vm_fault(map, va, ftype, FALSE);
#ifdef DEBUG
		if (rv && MDB_ISPID(p->p_pid))
			printf("vm_fault(%x, %x, %x, 0) -> %x\n",
			       map, va, ftype, rv);
#endif
		/*
		 * If this was a stack access we keep track of the maximum
		 * accessed stack size.  Also, if vm_fault gets a protection
		 * failure it is due to accessing the stack region outside
		 * the current limit and we need to reflect that as an access
		 * error.