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author | Stefan Hajnoczi <stefanha@gmail.com> | 2008-06-04 21:09:59 +0100 |
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committer | Michael Brown <mcb30@etherboot.org> | 2008-06-05 00:45:50 +0100 |
commit | 04bc50f0253da1a8fe29ed029ee2134126b664db (patch) | |
tree | 06d3945d6c4166f06c1c9f44db3737ee8b3c8ca2 /src/core/gdbstub.c | |
parent | 831db76ff7275ae33cfb95ba9b7cfed337464ebd (diff) | |
download | ipxe-04bc50f0253da1a8fe29ed029ee2134126b664db.zip ipxe-04bc50f0253da1a8fe29ed029ee2134126b664db.tar.gz ipxe-04bc50f0253da1a8fe29ed029ee2134126b664db.tar.bz2 |
[GDB] Add GDB stub for remote debugging
See http://etherboot.org/wiki/dev/gdbstub for documentation.
Diffstat (limited to 'src/core/gdbstub.c')
-rw-r--r-- | src/core/gdbstub.c | 330 |
1 files changed, 330 insertions, 0 deletions
diff --git a/src/core/gdbstub.c b/src/core/gdbstub.c new file mode 100644 index 0000000..213887b --- /dev/null +++ b/src/core/gdbstub.c @@ -0,0 +1,330 @@ +/* + * Copyright (C) 2008 Stefan Hajnoczi <stefanha@gmail.com>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/** + * @file + * + * GDB stub for remote debugging + * + */ + +#include <stdlib.h> +#include <stddef.h> +#include <stdio.h> +#include <ctype.h> +#include <assert.h> +#include <gpxe/process.h> +#include <gpxe/serial.h> +#include "gdbmach.h" + +enum { + POSIX_EINVAL = 0x1c /* used to report bad arguments to GDB */ +}; + +struct gdbstub { + int signo; + gdbreg_t *regs; + int exit_handler; /* leave interrupt handler */ + + void ( * parse ) ( struct gdbstub *stub, char ch ); + uint8_t cksum1; + + /* Buffer for payload data when parsing a packet. Once the + * packet has been received, this buffer is used to hold + * the reply payload. */ + char payload [ 256 ]; + int len; +}; + +/* Packet parser states */ +static void gdbstub_state_new ( struct gdbstub *stub, char ch ); +static void gdbstub_state_data ( struct gdbstub *stub, char ch ); +static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ); +static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ); +static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ); + +static uint8_t gdbstub_from_hex_digit ( char ch ) { + return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf; +} + +static uint8_t gdbstub_to_hex_digit ( uint8_t b ) { + b &= 0xf; + return ( b < 0xa ? '0' : 'a' - 0xa ) + b; +} + +static void gdbstub_from_hex_buf ( char *dst, char *src, int len ) { + while ( len-- > 0 ) { + *dst = gdbstub_from_hex_digit ( *src++ ); + if ( len-- > 0 ) { + *dst = (*dst << 4) | gdbstub_from_hex_digit ( *src++ ); + } + dst++; + } +} + +static void gdbstub_to_hex_buf ( char *dst, char *src, int len ) { + while ( len-- > 0 ) { + *dst++ = gdbstub_to_hex_digit ( *src >> 4 ); + *dst++ = gdbstub_to_hex_digit ( *src++ ); + } +} + +static uint8_t gdbstub_cksum ( char *data, int len ) { + uint8_t cksum = 0; + while ( len-- > 0 ) { + cksum += ( uint8_t ) *data++; + } + return cksum; +} + +static int gdbstub_getchar ( struct gdbstub *stub ) { + if ( stub->exit_handler ) { + return -1; + } + return serial_getc(); +} + +static void gdbstub_putchar ( struct gdbstub * stub __unused, char ch ) { + serial_putc ( ch ); +} + +static void gdbstub_tx_packet ( struct gdbstub *stub ) { + uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len ); + int i; + + gdbstub_putchar ( stub, '$' ); + for ( i = 0; i < stub->len; i++ ) { + gdbstub_putchar ( stub, stub->payload [ i ] ); + } + gdbstub_putchar ( stub, '#' ); + gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum >> 4 ) ); + gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum ) ); + + stub->parse = gdbstub_state_wait_ack; +} + +/* GDB commands */ +static void gdbstub_send_ok ( struct gdbstub *stub ) { + stub->payload [ 0 ] = 'O'; + stub->payload [ 1 ] = 'K'; + stub->len = 2; + gdbstub_tx_packet ( stub ); +} + +static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) { + stub->payload [ 0 ] = reply; + stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 ); + stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num ); + stub->len = 3; + gdbstub_tx_packet ( stub ); +} + +/* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */ +static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) { + int i; + char ch = 0; + int argc = 0; + unsigned long val = 0; + for ( i = 1; i < stub->len && argc < nargs; i++ ) { + ch = stub->payload [ i ]; + if ( ch == ':' ) { + break; + } else if ( ch == ',' ) { + args [ argc++ ] = val; + val = 0; + } else { + val = ( val << 4 ) | gdbstub_from_hex_digit ( ch ); + } + } + if ( stop_idx ) { + *stop_idx = i; + } + if ( argc < nargs ) { + args [ argc++ ] = val; + } + return ( ( i == stub->len || ch == ':' ) && argc == nargs ); +} + +static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) { + gdbstub_send_num_packet ( stub, 'E', errno ); +} + +static void gdbstub_report_signal ( struct gdbstub *stub ) { + gdbstub_send_num_packet ( stub, 'S', stub->signo ); +} + +static void gdbstub_read_regs ( struct gdbstub *stub ) { + gdbstub_to_hex_buf ( stub->payload, ( char * ) stub->regs, GDBMACH_SIZEOF_REGS ); + stub->len = GDBMACH_SIZEOF_REGS * 2; + gdbstub_tx_packet ( stub ); +} + +static void gdbstub_write_regs ( struct gdbstub *stub ) { + if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) { + gdbstub_send_errno ( stub, POSIX_EINVAL ); + return; + } + gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], stub->len ); + gdbstub_send_ok ( stub ); +} + +static void gdbstub_read_mem ( struct gdbstub *stub ) { + unsigned long args [ 2 ]; + if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) { + gdbstub_send_errno ( stub, POSIX_EINVAL ); + return; + } + args [ 1 ] = ( args [ 1 ] < sizeof stub->payload / 2 ) ? args [ 1 ] : sizeof stub->payload / 2; + gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] ); + stub->len = args [ 1 ] * 2; + gdbstub_tx_packet ( stub ); +} + +static void gdbstub_write_mem ( struct gdbstub *stub ) { + unsigned long args [ 2 ]; + int colon; + if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) || + colon >= stub->len || stub->payload [ colon ] != ':' || + ( stub->len - colon - 1 ) % 2 != 0 ) { + gdbstub_send_errno ( stub, POSIX_EINVAL ); + return; + } + gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], stub->len - colon - 1 ); + gdbstub_send_ok ( stub ); +} + +static void gdbstub_continue ( struct gdbstub *stub, int single_step ) { + gdbreg_t pc; + if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) { + gdbmach_set_pc ( stub->regs, pc ); + } + gdbmach_set_single_step ( stub->regs, single_step ); + stub->exit_handler = 1; + /* Reply will be sent when we hit the next breakpoint or interrupt */ +} + +static void gdbstub_rx_packet ( struct gdbstub *stub ) { + switch ( stub->payload [ 0 ] ) { + case '?': + gdbstub_report_signal ( stub ); + break; + case 'g': + gdbstub_read_regs ( stub ); + break; + case 'G': + gdbstub_write_regs ( stub ); + break; + case 'm': + gdbstub_read_mem ( stub ); + break; + case 'M': + gdbstub_write_mem ( stub ); + break; + case 'c': + gdbstub_continue ( stub, 0 ); + break; + case 's': + gdbstub_continue ( stub, 1 ); + break; + default: + stub->len = 0; + gdbstub_tx_packet ( stub ); + break; + } +} + +/* GDB packet parser */ +static void gdbstub_state_new ( struct gdbstub *stub, char ch ) { + if ( ch == '$' ) { + stub->len = 0; + stub->parse = gdbstub_state_data; + } +} + +static void gdbstub_state_data ( struct gdbstub *stub, char ch ) { + if ( ch == '#' ) { + stub->parse = gdbstub_state_cksum1; + } else if ( ch == '$' ) { + stub->len = 0; /* retry new packet */ + } else { + /* If the length exceeds our buffer, let the checksum fail */ + if ( stub->len < ( int ) sizeof stub->payload ) { + stub->payload [ stub->len++ ] = ch; + } + } +} + +static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) { + stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4; + stub->parse = gdbstub_state_cksum2; +} + +static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) { + uint8_t their_cksum; + uint8_t our_cksum; + + stub->parse = gdbstub_state_new; + their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch ); + our_cksum = gdbstub_cksum ( stub->payload, stub->len ); + if ( their_cksum == our_cksum ) { + gdbstub_putchar ( stub, '+' ); + if ( stub->len > 0 ) { + gdbstub_rx_packet ( stub ); + } + } else { + gdbstub_putchar ( stub, '-' ); + } +} + +static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) { + if ( ch == '+' ) { + stub->parse = gdbstub_state_new; + } else if ( ch == '-' ) { + gdbstub_tx_packet ( stub ); /* retransmit */ + } +} + +static void gdbstub_parse ( struct gdbstub *stub, char ch ) { + stub->parse ( stub, ch ); +} + +static struct gdbstub stub = { + .parse = gdbstub_state_new +}; + +__cdecl void gdbstub_handler ( int signo, gdbreg_t *regs ) { + int ch; + stub.signo = signo; + stub.regs = regs; + stub.exit_handler = 0; + gdbstub_report_signal ( &stub ); + while ( ( ch = gdbstub_getchar( &stub ) ) != -1 ) { + gdbstub_parse ( &stub, ch ); + } +} + +/* Activity monitor to detect packets from GDB when we are not active */ +static void gdbstub_activity_step ( struct process *process __unused ) { + if ( serial_ischar() ) { + gdbmach_breakpoint(); + } +} + +struct process gdbstub_activity_process __permanent_process = { + .step = gdbstub_activity_step, +}; |