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+/*
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+ * Copyright (C) 2008 Stefan Hajnoczi <stefanha@gmail.com>.
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License as
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+ * published by the Free Software Foundation; either version 2 of the
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+ * License, or any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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+ */
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+
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+/**
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+ * @file
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+ *
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+ * GDB stub for remote debugging
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+ *
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+ */
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+
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+#include <stdlib.h>
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+#include <stddef.h>
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+#include <stdio.h>
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+#include <ctype.h>
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+#include <assert.h>
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+#include <gpxe/process.h>
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+#include <gpxe/serial.h>
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+#include "gdbmach.h"
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+
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+enum {
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+ POSIX_EINVAL = 0x1c /* used to report bad arguments to GDB */
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+};
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+
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+struct gdbstub {
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+ int signo;
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+ gdbreg_t *regs;
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+ int exit_handler; /* leave interrupt handler */
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+
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+ void ( * parse ) ( struct gdbstub *stub, char ch );
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+ uint8_t cksum1;
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+
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+ /* Buffer for payload data when parsing a packet. Once the
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+ * packet has been received, this buffer is used to hold
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+ * the reply payload. */
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+ char payload [ 256 ];
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+ int len;
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+};
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+
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+/* Packet parser states */
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+static void gdbstub_state_new ( struct gdbstub *stub, char ch );
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+static void gdbstub_state_data ( struct gdbstub *stub, char ch );
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+static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch );
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+static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch );
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+static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch );
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+
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+static uint8_t gdbstub_from_hex_digit ( char ch ) {
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+ return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf;
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+}
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+
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+static uint8_t gdbstub_to_hex_digit ( uint8_t b ) {
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+ b &= 0xf;
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+ return ( b < 0xa ? '0' : 'a' - 0xa ) + b;
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+}
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+
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+static void gdbstub_from_hex_buf ( char *dst, char *src, int len ) {
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+ while ( len-- > 0 ) {
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+ *dst = gdbstub_from_hex_digit ( *src++ );
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+ if ( len-- > 0 ) {
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+ *dst = (*dst << 4) | gdbstub_from_hex_digit ( *src++ );
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+ }
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+ dst++;
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+ }
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+}
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+
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+static void gdbstub_to_hex_buf ( char *dst, char *src, int len ) {
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+ while ( len-- > 0 ) {
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+ *dst++ = gdbstub_to_hex_digit ( *src >> 4 );
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+ *dst++ = gdbstub_to_hex_digit ( *src++ );
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+ }
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+}
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+
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+static uint8_t gdbstub_cksum ( char *data, int len ) {
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+ uint8_t cksum = 0;
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+ while ( len-- > 0 ) {
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+ cksum += ( uint8_t ) *data++;
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+ }
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+ return cksum;
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+}
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+
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+static int gdbstub_getchar ( struct gdbstub *stub ) {
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+ if ( stub->exit_handler ) {
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+ return -1;
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+ }
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+ return serial_getc();
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+}
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+
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+static void gdbstub_putchar ( struct gdbstub * stub __unused, char ch ) {
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+ serial_putc ( ch );
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+}
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+
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+static void gdbstub_tx_packet ( struct gdbstub *stub ) {
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+ uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len );
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+ int i;
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+
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+ gdbstub_putchar ( stub, '$' );
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+ for ( i = 0; i < stub->len; i++ ) {
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+ gdbstub_putchar ( stub, stub->payload [ i ] );
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+ }
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+ gdbstub_putchar ( stub, '#' );
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+ gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum >> 4 ) );
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+ gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum ) );
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+
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+ stub->parse = gdbstub_state_wait_ack;
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+}
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+
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+/* GDB commands */
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+static void gdbstub_send_ok ( struct gdbstub *stub ) {
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+ stub->payload [ 0 ] = 'O';
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+ stub->payload [ 1 ] = 'K';
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+ stub->len = 2;
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+ gdbstub_tx_packet ( stub );
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+}
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+
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+static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) {
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+ stub->payload [ 0 ] = reply;
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+ stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 );
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+ stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num );
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+ stub->len = 3;
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+ gdbstub_tx_packet ( stub );
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+}
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+
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+/* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */
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+static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) {
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+ int i;
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+ char ch = 0;
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+ int argc = 0;
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+ unsigned long val = 0;
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+ for ( i = 1; i < stub->len && argc < nargs; i++ ) {
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+ ch = stub->payload [ i ];
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+ if ( ch == ':' ) {
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+ break;
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+ } else if ( ch == ',' ) {
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+ args [ argc++ ] = val;
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+ val = 0;
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+ } else {
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+ val = ( val << 4 ) | gdbstub_from_hex_digit ( ch );
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+ }
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+ }
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+ if ( stop_idx ) {
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+ *stop_idx = i;
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+ }
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+ if ( argc < nargs ) {
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+ args [ argc++ ] = val;
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+ }
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+ return ( ( i == stub->len || ch == ':' ) && argc == nargs );
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+}
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+
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+static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) {
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+ gdbstub_send_num_packet ( stub, 'E', errno );
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+}
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+
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+static void gdbstub_report_signal ( struct gdbstub *stub ) {
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+ gdbstub_send_num_packet ( stub, 'S', stub->signo );
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+}
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+
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+static void gdbstub_read_regs ( struct gdbstub *stub ) {
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+ gdbstub_to_hex_buf ( stub->payload, ( char * ) stub->regs, GDBMACH_SIZEOF_REGS );
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+ stub->len = GDBMACH_SIZEOF_REGS * 2;
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+ gdbstub_tx_packet ( stub );
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+}
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+
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+static void gdbstub_write_regs ( struct gdbstub *stub ) {
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+ if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) {
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+ gdbstub_send_errno ( stub, POSIX_EINVAL );
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+ return;
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+ }
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+ gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], stub->len );
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+ gdbstub_send_ok ( stub );
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+}
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+
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+static void gdbstub_read_mem ( struct gdbstub *stub ) {
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+ unsigned long args [ 2 ];
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+ if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
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+ gdbstub_send_errno ( stub, POSIX_EINVAL );
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+ return;
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+ }
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+ args [ 1 ] = ( args [ 1 ] < sizeof stub->payload / 2 ) ? args [ 1 ] : sizeof stub->payload / 2;
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+ gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] );
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+ stub->len = args [ 1 ] * 2;
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+ gdbstub_tx_packet ( stub );
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+}
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+
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+static void gdbstub_write_mem ( struct gdbstub *stub ) {
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+ unsigned long args [ 2 ];
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+ int colon;
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+ if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) ||
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+ colon >= stub->len || stub->payload [ colon ] != ':' ||
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+ ( stub->len - colon - 1 ) % 2 != 0 ) {
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+ gdbstub_send_errno ( stub, POSIX_EINVAL );
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+ return;
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+ }
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+ gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], stub->len - colon - 1 );
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+ gdbstub_send_ok ( stub );
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+}
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+
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+static void gdbstub_continue ( struct gdbstub *stub, int single_step ) {
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+ gdbreg_t pc;
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+ if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) {
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+ gdbmach_set_pc ( stub->regs, pc );
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+ }
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+ gdbmach_set_single_step ( stub->regs, single_step );
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+ stub->exit_handler = 1;
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+ /* Reply will be sent when we hit the next breakpoint or interrupt */
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+}
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+
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+static void gdbstub_rx_packet ( struct gdbstub *stub ) {
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+ switch ( stub->payload [ 0 ] ) {
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+ case '?':
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+ gdbstub_report_signal ( stub );
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+ break;
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+ case 'g':
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+ gdbstub_read_regs ( stub );
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+ break;
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+ case 'G':
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+ gdbstub_write_regs ( stub );
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+ break;
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+ case 'm':
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+ gdbstub_read_mem ( stub );
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+ break;
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+ case 'M':
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+ gdbstub_write_mem ( stub );
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+ break;
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+ case 'c':
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+ gdbstub_continue ( stub, 0 );
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+ break;
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+ case 's':
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+ gdbstub_continue ( stub, 1 );
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+ break;
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+ default:
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+ stub->len = 0;
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+ gdbstub_tx_packet ( stub );
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+ break;
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+ }
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+}
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+
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+/* GDB packet parser */
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+static void gdbstub_state_new ( struct gdbstub *stub, char ch ) {
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+ if ( ch == '$' ) {
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+ stub->len = 0;
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+ stub->parse = gdbstub_state_data;
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+ }
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+}
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+
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+static void gdbstub_state_data ( struct gdbstub *stub, char ch ) {
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260
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+ if ( ch == '#' ) {
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+ stub->parse = gdbstub_state_cksum1;
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262
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+ } else if ( ch == '$' ) {
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+ stub->len = 0; /* retry new packet */
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+ } else {
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+ /* If the length exceeds our buffer, let the checksum fail */
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266
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+ if ( stub->len < ( int ) sizeof stub->payload ) {
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267
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+ stub->payload [ stub->len++ ] = ch;
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+ }
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+ }
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+}
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+
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+static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) {
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+ stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4;
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+ stub->parse = gdbstub_state_cksum2;
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+}
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+
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+static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) {
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+ uint8_t their_cksum;
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+ uint8_t our_cksum;
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+
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281
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+ stub->parse = gdbstub_state_new;
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+ their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch );
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283
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+ our_cksum = gdbstub_cksum ( stub->payload, stub->len );
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284
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+ if ( their_cksum == our_cksum ) {
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285
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+ gdbstub_putchar ( stub, '+' );
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286
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+ if ( stub->len > 0 ) {
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287
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+ gdbstub_rx_packet ( stub );
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288
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+ }
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289
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+ } else {
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290
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+ gdbstub_putchar ( stub, '-' );
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291
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+ }
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292
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+}
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293
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+
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294
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+static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) {
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295
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+ if ( ch == '+' ) {
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296
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+ stub->parse = gdbstub_state_new;
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297
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+ } else if ( ch == '-' ) {
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298
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+ gdbstub_tx_packet ( stub ); /* retransmit */
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299
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+ }
|
|
|
300
|
+}
|
|
|
301
|
+
|
|
|
302
|
+static void gdbstub_parse ( struct gdbstub *stub, char ch ) {
|
|
|
303
|
+ stub->parse ( stub, ch );
|
|
|
304
|
+}
|
|
|
305
|
+
|
|
|
306
|
+static struct gdbstub stub = {
|
|
|
307
|
+ .parse = gdbstub_state_new
|
|
|
308
|
+};
|
|
|
309
|
+
|
|
|
310
|
+__cdecl void gdbstub_handler ( int signo, gdbreg_t *regs ) {
|
|
|
311
|
+ int ch;
|
|
|
312
|
+ stub.signo = signo;
|
|
|
313
|
+ stub.regs = regs;
|
|
|
314
|
+ stub.exit_handler = 0;
|
|
|
315
|
+ gdbstub_report_signal ( &stub );
|
|
|
316
|
+ while ( ( ch = gdbstub_getchar( &stub ) ) != -1 ) {
|
|
|
317
|
+ gdbstub_parse ( &stub, ch );
|
|
|
318
|
+ }
|
|
|
319
|
+}
|
|
|
320
|
+
|
|
|
321
|
+/* Activity monitor to detect packets from GDB when we are not active */
|
|
|
322
|
+static void gdbstub_activity_step ( struct process *process __unused ) {
|
|
|
323
|
+ if ( serial_ischar() ) {
|
|
|
324
|
+ gdbmach_breakpoint();
|
|
|
325
|
+ }
|
|
|
326
|
+}
|
|
|
327
|
+
|
|
|
328
|
+struct process gdbstub_activity_process __permanent_process = {
|
|
|
329
|
+ .step = gdbstub_activity_step,
|
|
|
330
|
+};
|
Stefan Hajnoczi
17 роки тому