4.4BSD/usr/src/sys/i386/i386/kgdb_stub.c
/*
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* 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, Lawrence Berkeley Laboratories.
*
* 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.
*
* @(#)kgdb_stub.c 8.1 (Berkeley) 6/11/93
*/
/*
* "Stub" to allow remote cpu to debug over a serial line using gdb.
*/
#ifdef KGDB
#ifndef lint
static char rcsid[] = "$Header: /u/donn/c/gdb/kernel/RCS/kgdb_stub.c,v 1.2 91/03/31 19:22:46 donn Exp Locker: donn $";
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <machine/trap.h>
#include <machine/cpu.h>
#include <machine/psl.h>
#include <machine/reg.h>
#include <sys/buf.h>
#include <i386/i386/cons.h>
#include <sys/errno.h>
#include <i386/i386/kgdb_proto.h>
#include <machine/remote-sl.h>
extern int kernacc();
#if 0
extern void chgkprot();
#endif
#ifndef KGDBDEV
#define KGDBDEV -1
#endif
#ifndef KGDBRATE
#define KGDBRATE 9600
#endif
int kgdb_dev = KGDBDEV; /* remote debugging device (-1 if none) */
int kgdb_rate = KGDBRATE; /* remote debugging baud rate */
int kgdb_active = 0; /* remote debugging active if != 0 */
int kgdb_debug_init = 0; /* != 0 waits for remote at system init */
int kgdb_debug_panic = 1; /* != 0 waits for remote on panic */
int kgdb_debug = 3;
#define GETC ((*kgdb_getc)(kgdb_dev))
#define PUTC(c) ((*kgdb_putc)(kgdb_dev, c))
#define PUTESC(c) { \
if (c == FRAME_END) { \
PUTC(FRAME_ESCAPE); \
c = TRANS_FRAME_END; \
} else if (c == FRAME_ESCAPE) { \
PUTC(FRAME_ESCAPE); \
c = TRANS_FRAME_ESCAPE; \
} \
PUTC(c); \
}
static int (*kgdb_getc)();
static int (*kgdb_putc)();
/*
* Send a message. The host gets one chance to read it.
*/
static void
kgdb_send(type, bp, len)
register u_char type;
register u_char *bp;
register int len;
{
register u_char csum;
register u_char *ep = bp + len;
csum = type;
PUTESC(type)
while (bp < ep) {
type = *bp++;
csum += type;
PUTESC(type)
}
csum = -csum;
PUTESC(csum)
PUTC(FRAME_END);
}
static int
kgdb_recv(bp, lenp)
u_char *bp;
int *lenp;
{
register u_char c, csum;
register int escape, len;
register int type;
csum = len = escape = 0;
type = -1;
while (1) {
c = GETC;
switch (c) {
case FRAME_ESCAPE:
escape = 1;
continue;
case TRANS_FRAME_ESCAPE:
if (escape)
c = FRAME_ESCAPE;
break;
case TRANS_FRAME_END:
if (escape)
c = FRAME_END;
break;
case FRAME_END:
if (type < 0 || --len < 0) {
csum = len = escape = 0;
type = -1;
continue;
}
if (csum != 0) {
return (0);
}
*lenp = len;
return type;
}
csum += c;
if (type < 0) {
type = c;
escape = 0;
continue;
}
if (++len > SL_BUFSIZE) {
while (GETC != FRAME_END)
;
return (0);
}
*bp++ = c;
escape = 0;
}
}
/*
* Translate a trap number into a unix compatible signal value.
* (gdb only understands unix signal numbers).
*/
static int
computeSignal(type)
int type;
{
int sigval;
switch (type) {
case T_RESADFLT:
case T_PRIVINFLT:
case T_RESOPFLT:
case T_ALIGNFLT:
case T_FPOPFLT:
sigval = SIGILL;
break;
case T_BPTFLT:
case T_TRCTRAP:
case T_KDBTRAP:
sigval = SIGTRAP;
break;
case T_ARITHTRAP:
case T_DIVIDE:
case T_OFLOW:
case T_BOUND:
case T_DNA:
sigval = SIGFPE;
break;
case T_SEGFLT:
case T_PROTFLT:
case T_SEGNPFLT:
case T_BUSERR:
sigval = SIGBUS;
break;
case T_PAGEFLT:
case T_TABLEFLT:
sigval = SIGSEGV;
break;
case T_SYSCALL: /* ??? */
case T_ASTFLT: /* ??? */
case T_KSPNOTVAL: /* ??? */
case T_NMI: /* ??? */
case T_DOUBLEFLT: /* ??? */
case T_TSSFLT: /* ??? */
case T_STKFLT: /* ??? */
case T_RESERVED: /* ??? */
default:
sigval = SIGEMT;
break;
}
return (sigval);
}
/*
* Trap into kgdb to wait for debugger to connect,
* noting on the console why nothing else is going on.
*/
kgdb_connect(verbose)
int verbose;
{
if (verbose)
printf("kgdb waiting...");
#ifdef DONN
if (kgdb_debug > 3)
pg("kgdb_connect: trapping\n");
#endif
/* trap into kgdb */
asm volatile ("int3");
if (verbose)
printf("connected.\n");
}
/*
* Decide what to do on panic.
*/
kgdb_panic()
{
if (kgdb_active == 0 && kgdb_debug_panic)
kgdb_connect(1);
}
/*
* Definitions exported from gdb.
*/
#define NUM_REGS 16
#define REGISTER_BYTES (NUM_REGS * 4)
#define REGISTER_BYTE(N) ((N)*4)
#define GDB_SR 8
#define GDB_PC 9
static inline void
kgdb_copy(register u_char *src, register u_char *dst, register u_int nbytes)
{
register u_char *ep = src + nbytes;
while (src < ep)
*dst++ = *src++;
}
#ifndef tISP
#define tISP (5) /* XXX */
#endif
static const char trapmap[] = /* from gdb */
{
tEAX, tECX, tEDX, tEBX,
tISP, tEBP, tESI, tEDI,
tEIP, tEFLAGS, tCS, tDS, /* tSS doesn't exist for kernel trap */
tDS, tES, tES, tES /* lies: no fs or gs */
};
static inline void
regs_to_gdb(struct trapframe *fp, register u_long *gdb)
{
register const char *tp;
register u_long *regs = (u_long *)fp;
for (tp = trapmap; tp < &trapmap[sizeof trapmap]; ++tp)
*gdb++ = regs[*tp];
}
static inline void
gdb_to_regs(struct trapframe *fp, register u_long *gdb)
{
register const char *tp;
register u_long *regs = (u_long *)fp;
for (tp = trapmap; tp < &trapmap[sizeof trapmap]; ++tp)
regs[*tp] = *gdb++;
}
static u_long reg_cache[NUM_REGS];
static u_char inbuffer[SL_BUFSIZE];
static u_char outbuffer[SL_BUFSIZE];
/*
* This function does all command procesing for interfacing to
* a remote gdb.
*/
int
kgdb_trap(int type, struct trapframe *frame)
{
register u_long len;
u_char *addr;
register u_char *cp;
register u_char out, in;
register int outlen;
int inlen;
u_long gdb_regs[NUM_REGS];
int saved_kgdb_active = kgdb_active;
if (kgdb_dev < 0) {
/* not debugging */
return (0);
}
if (kgdb_active == 0) {
#ifdef DONN
if (kgdb_debug > 3)
pg("kgdb_trap: start initialization\n");
#endif
if (type != T_BPTFLT) {
/* No debugger active -- let trap handle this. */
return (0);
}
kgdb_getc = 0;
for (inlen = 0; constab[inlen].cn_probe; inlen++)
if (major(constab[inlen].cn_dev) == major(kgdb_dev)) {
kgdb_getc = constab[inlen].cn_getc;
kgdb_putc = constab[inlen].cn_putc;
break;
}
#ifdef DONN
if (kgdb_debug > 3)
pg("kgdb_trap: kgdb_getc = %x, kgdb_putc = %x\n",
kgdb_getc, kgdb_putc);
#endif
if (kgdb_getc == 0 || kgdb_putc == 0)
return (0);
/*
* If the packet that woke us up isn't an exec packet,
* ignore it since there is no active debugger. Also,
* we check that it's not an ack to be sure that the
* remote side doesn't send back a response after the
* local gdb has exited. Otherwise, the local host
* could trap into gdb if it's running a gdb kernel too.
*/
in = GETC;
#ifdef DONN
if (kgdb_debug > 3)
pg("kgdb_trap: looking for sync %x\n", in);
#endif
/*
* If we came in asynchronously through the serial line,
* the framing character is eaten by the receive interrupt,
* but if we come in through a synchronous trap (i.e., via
* kgdb_connect()), we will see the extra character.
*/
if (in == FRAME_END)
in = GETC;
if (KGDB_CMD(in) != KGDB_EXEC || (in & KGDB_ACK) != 0)
return (0);
while (GETC != FRAME_END)
;
/*
* Do the printf *before* we ack the message. This way
* we won't drop any inbound characters while we're
* doing the polling printf.
*/
printf("kgdb started from device %x\n", kgdb_dev);
kgdb_send(in | KGDB_ACK, (u_char *)0, 0);
kgdb_active = 1;
}
/*
* Stick frame regs into our reg cache then tell remote host
* that an exception has occured.
*/
regs_to_gdb(frame, gdb_regs);
if (saved_kgdb_active == kgdb_active) {
/*
* Don't send an asynchronous SIGNAL message when we hit
* the first breakpoint. Otherwise, we will drop the incoming
* packet while we output this one (and on entry the other
* side isn't interested in the SIGNAL type -- if it is,
* it will have used a signal packet.)
*/
outbuffer[0] = computeSignal(type);
kgdb_send(KGDB_SIGNAL, outbuffer, 1);
}
while (1) {
in = kgdb_recv(inbuffer, &inlen);
if (in == 0 || (in & KGDB_ACK))
/* Ignore inbound acks and error conditions. */
continue;
out = in | KGDB_ACK;
switch (KGDB_CMD(in)) {
case KGDB_SIGNAL:
/*
* if this command came from a running gdb,
* answer it -- the other guy has no way of
* knowing if we're in or out of this loop
* when he issues a "remote-signal". (Note
* that without the length check, we could
* loop here forever if the ourput line is
* looped back or the remote host is echoing.)
*/
if (inlen == 0) {
outbuffer[0] = computeSignal(type);
kgdb_send(KGDB_SIGNAL, outbuffer, 1);
}
continue;
case KGDB_REG_R:
case KGDB_REG_R | KGDB_DELTA:
cp = outbuffer;
outlen = 0;
for (len = inbuffer[0]; len < NUM_REGS; ++len) {
if (reg_cache[len] != gdb_regs[len] ||
(in & KGDB_DELTA) == 0) {
if (outlen + 5 > SL_MAXMSG) {
out |= KGDB_MORE;
break;
}
cp[outlen] = len;
kgdb_copy((u_char *)&gdb_regs[len],
&cp[outlen + 1], 4);
reg_cache[len] = gdb_regs[len];
outlen += 5;
}
}
break;
case KGDB_REG_W:
case KGDB_REG_W | KGDB_DELTA:
cp = inbuffer;
for (len = 0; len < inlen; len += 5) {
register int j = cp[len];
kgdb_copy(&cp[len + 1],
(u_char *)&gdb_regs[j], 4);
reg_cache[j] = gdb_regs[j];
}
gdb_to_regs(frame, gdb_regs);
outlen = 0;
break;
case KGDB_MEM_R:
len = inbuffer[0];
kgdb_copy(&inbuffer[1], (u_char *)&addr, 4);
if (len + 1 > SL_MAXMSG) {
outlen = 1;
outbuffer[0] = E2BIG;
} else if (!kgdb_acc(addr, len, B_READ)) {
outlen = 1;
outbuffer[0] = EFAULT;
} else {
outlen = len + 1;
outbuffer[0] = 0;
kgdb_copy(addr, &outbuffer[1], len);
}
break;
case KGDB_MEM_W:
len = inlen - 4;
kgdb_copy(inbuffer, (u_char *)&addr, 4);
outlen = 1;
if (!kgdb_acc(addr, len, B_READ))
outbuffer[0] = EFAULT;
else {
outbuffer[0] = 0;
#if 0 /* 386 can't write-protect against kernel! */
if (!kgdb_acc(addr, len, B_WRITE))
chgkprot(addr, len, B_WRITE);
#endif
kgdb_copy(&inbuffer[4], addr, len);
}
break;
case KGDB_KILL:
kgdb_active = 0;
printf("kgdb detached\n");
/* fall through */
case KGDB_CONT:
kgdb_send(out, 0, 0);
frame->tf_eflags &=~ PSL_T;
return (1);
case KGDB_STEP:
kgdb_send(out, 0, 0);
frame->tf_eflags |= PSL_T;
return (1);
case KGDB_EXEC:
default:
/* Unknown command. Ack with a null message. */
outlen = 0;
break;
}
/* Send the reply */
kgdb_send(out, outbuffer, outlen);
}
}
/*
* XXX do kernacc call if safe, otherwise attempt
* to simulate by simple bounds-checking.
*/
kgdb_acc(addr, len, rw)
caddr_t addr;
{
extern char proc0paddr[], kstack[]; /* XXX! */
extern char *kernel_map; /* XXX! */
if (kstack <= addr && addr < kstack + UPAGES * NBPG)
/*
* Horrid hack -- the kernel stack is mapped
* by the user page table, but we guarantee (?) their presence.
*/
return (1);
if (kernel_map != NULL)
return (kernacc(addr, len, rw));
#if 0
if (addr < proc0paddr + UPAGES * NBPG ||
kstack <= addr && addr < kstack + UPAGES * NBPG)
return (1);
#endif
return (0);
}
#endif