freebsd-skq/sys/gdb/gdb_int.h
cem b6995dbc52 gdb(4): Implement support for NoAckMode
When the underlying debugport transport is reliable, GDB's additional
checksums and acknowledgements are redundant.  NoAckMode eliminates the
the acks and allows us to skip checking RX checksums.  The GDB packet
framing does not change, so unfortunately (valid) checksums are still
included as message trailers.

The gdb(4) stub in FreeBSD advertises support for the feature in response to
the client's 'qSupported' request IFF the current debugport has the
gdb_dbfeatures flag GDB_DBGP_FEAT_RELIABLE set.  Currently, only netgdb(4)
supports this feature.

If the remote GDB client supports the feature and does not have it disabled
via a GDB configuration knob, it may instruct our gdb(4) stub to enter
NoAckMode.  Unless and until it issues that command, we must continue to
transmit acks as usual (and for now, we continue to wait until we receive
them as well, even if we know the debugport is on a reliable transport).

In the kernel sources, the sense of the flag representing the state of the
feature is reversed from that of the GDB command.  (I.e., it is
'gdb_ackmode', not 'gdb_noackmode.')  This is to avoid confusing double-
negative conditions.

For reference, see:
  * https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html
  * https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#QStartNoAckMode

Reviewed by:	jhb, markj (both earlier version)
Differential Revision:	https://reviews.freebsd.org/D21761
2019-10-17 22:37:25 +00:00

154 lines
3.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2004 Marcel Moolenaar
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef _GDB_GDB_INT_H_
#define _GDB_GDB_INT_H_
#include "opt_ddb.h"
#include <sys/sysctl.h>
#ifdef DDB
#include <ddb/ddb.h>
#endif
#ifndef EOF
#define EOF (-1)
#endif
SYSCTL_DECL(_debug_gdb);
extern struct gdb_dbgport *gdb_cur;
extern int gdb_listening;
void gdb_consinit(void);
extern char *gdb_rxp;
extern size_t gdb_rxsz;
extern char *gdb_txp;
extern bool gdb_ackmode;
#ifdef DDB
/* If set, return to DDB when controlling GDB detaches. */
extern bool gdb_return_to_ddb;
#endif
int gdb_rx_begin(void);
int gdb_rx_equal(const char *);
int gdb_rx_mem(unsigned char *, size_t);
int gdb_rx_varhex(uintmax_t *);
static __inline int
gdb_rx_char(void)
{
int c;
if (gdb_rxsz > 0) {
c = *gdb_rxp++;
gdb_rxsz--;
} else
c = EOF;
return (c);
}
void gdb_tx_begin(char);
int gdb_tx_end(void);
int gdb_tx_mem(const unsigned char *, size_t);
void gdb_tx_reg(int);
bool gdb_txbuf_has_capacity(size_t);
int gdb_rx_bindata(unsigned char *data, size_t datalen, size_t *amt);
int gdb_search_mem(const unsigned char *addr, size_t size,
const unsigned char *pat, size_t patlen, const unsigned char **found);
static __inline void
gdb_tx_char(char c)
{
*gdb_txp++ = c;
}
static __inline int
gdb_tx_empty(void)
{
gdb_tx_begin('\0');
return (gdb_tx_end());
}
static __inline void
gdb_tx_hex(uintmax_t n, int sz)
{
gdb_txp += sprintf(gdb_txp, "%0*jx", sz, n);
}
static __inline int
gdb_tx_err(int err)
{
gdb_tx_begin('E');
gdb_tx_hex(err, 2);
return (gdb_tx_end());
}
static __inline int
gdb_tx_ok(void)
{
gdb_tx_begin('O');
gdb_tx_char('K');
return (gdb_tx_end());
}
static __inline void
gdb_tx_str(const char *s)
{
while (*s)
*gdb_txp++ = *s++;
}
static __inline void
gdb_tx_varhex(uintmax_t n)
{
gdb_txp += sprintf(gdb_txp, "%jx", n);
}
static __inline void
gdb_nack(void)
{
if (gdb_ackmode)
gdb_cur->gdb_putc('-');
}
static __inline void
gdb_ack(void)
{
if (gdb_ackmode)
gdb_cur->gdb_putc('+');
}
#endif /* !_GDB_GDB_INT_H_ */