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-rw-r--r--com32/gdbstub/gdbstub.c531
1 files changed, 531 insertions, 0 deletions
diff --git a/com32/gdbstub/gdbstub.c b/com32/gdbstub/gdbstub.c
new file mode 100644
index 00000000..77c9dcb9
--- /dev/null
+++ b/com32/gdbstub/gdbstub.c
@@ -0,0 +1,531 @@
+/*
+ * 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 <stdint.h>
+#include "serial.h"
+
+typedef uint32_t gdbreg_t;
+
+enum {
+ POSIX_EINVAL = 0x1c, /* used to report bad arguments to GDB */
+ SIZEOF_PAYLOAD = 256, /* buffer size of GDB payload data */
+ DR7_CLEAR = 0x00000400, /* disable hardware breakpoints */
+ DR6_CLEAR = 0xffff0ff0, /* clear breakpoint status */
+};
+
+/* The register snapshot, this must be in sync with interrupt handler and the
+ * GDB protocol. */
+enum {
+ GDBMACH_EAX,
+ GDBMACH_ECX,
+ GDBMACH_EDX,
+ GDBMACH_EBX,
+ GDBMACH_ESP,
+ GDBMACH_EBP,
+ GDBMACH_ESI,
+ GDBMACH_EDI,
+ GDBMACH_EIP,
+ GDBMACH_EFLAGS,
+ GDBMACH_CS,
+ GDBMACH_SS,
+ GDBMACH_DS,
+ GDBMACH_ES,
+ GDBMACH_FS,
+ GDBMACH_GS,
+ GDBMACH_NREGS,
+ GDBMACH_SIZEOF_REGS = GDBMACH_NREGS * sizeof ( gdbreg_t )
+};
+
+/* Breakpoint types */
+enum {
+ GDBMACH_BPMEM,
+ GDBMACH_BPHW,
+ GDBMACH_WATCH,
+ GDBMACH_RWATCH,
+ GDBMACH_AWATCH,
+};
+
+struct gdbstub {
+ int exit_handler; /* leave interrupt handler */
+
+ int signo;
+ gdbreg_t *regs;
+
+ 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 buf [ SIZEOF_PAYLOAD + 4 ]; /* $...PAYLOAD...#XX */
+ char *payload; /* start of payload */
+ int len; /* length of payload */
+};
+
+/** Hardware breakpoint, fields stored in x86 bit pattern form */
+struct hwbp {
+ int type; /* type (1=write watchpoint, 3=access watchpoint) */
+ unsigned long addr; /* linear address */
+ size_t len; /* length (0=1-byte, 1=2-byte, 3=4-byte) */
+ int enabled;
+};
+
+static struct hwbp hwbps [ 4 ];
+static gdbreg_t dr7 = DR7_CLEAR;
+
+static inline void gdbmach_set_pc ( gdbreg_t *regs, gdbreg_t pc ) {
+ regs [ GDBMACH_EIP ] = pc;
+}
+
+static inline void gdbmach_set_single_step ( gdbreg_t *regs, int step ) {
+ regs [ GDBMACH_EFLAGS ] &= ~( 1 << 8 ); /* Trace Flag (TF) */
+ regs [ GDBMACH_EFLAGS ] |= ( step << 8 );
+}
+
+static inline void gdbmach_breakpoint ( void ) {
+ __asm__ __volatile__ ( "int $3\n" );
+}
+
+static struct hwbp *gdbmach_find_hwbp ( int type, unsigned long addr, size_t len ) {
+ struct hwbp *available = NULL;
+ unsigned int i;
+ for ( i = 0; i < sizeof hwbps / sizeof hwbps [ 0 ]; i++ ) {
+ if ( hwbps [ i ].type == type && hwbps [ i ].addr == addr && hwbps [ i ].len == len ) {
+ return &hwbps [ i ];
+ }
+ if ( !hwbps [ i ].enabled ) {
+ available = &hwbps [ i ];
+ }
+ }
+ return available;
+}
+
+static void gdbmach_commit_hwbp ( struct hwbp *bp ) {
+ int regnum = bp - hwbps;
+
+ /* Set breakpoint address */
+ switch ( regnum ) {
+ case 0:
+ __asm__ __volatile__ ( "movl %0, %%dr0\n" : : "r" ( bp->addr ) );
+ break;
+ case 1:
+ __asm__ __volatile__ ( "movl %0, %%dr1\n" : : "r" ( bp->addr ) );
+ break;
+ case 2:
+ __asm__ __volatile__ ( "movl %0, %%dr2\n" : : "r" ( bp->addr ) );
+ break;
+ case 3:
+ __asm__ __volatile__ ( "movl %0, %%dr3\n" : : "r" ( bp->addr ) );
+ break;
+ }
+
+ /* Set type */
+ dr7 &= ~( 0x3 << ( 16 + 4 * regnum ) );
+ dr7 |= bp->type << ( 16 + 4 * regnum );
+
+ /* Set length */
+ dr7 &= ~( 0x3 << ( 18 + 4 * regnum ) );
+ dr7 |= bp->len << ( 18 + 4 * regnum );
+
+ /* Set/clear local enable bit */
+ dr7 &= ~( 0x3 << 2 * regnum );
+ dr7 |= bp->enabled << 2 * regnum;
+}
+
+int gdbmach_set_breakpoint ( int type, unsigned long addr, size_t len, int enable ) {
+ struct hwbp *bp;
+
+ /* Check and convert breakpoint type to x86 type */
+ switch ( type ) {
+ case GDBMACH_WATCH:
+ type = 0x1;
+ break;
+ case GDBMACH_AWATCH:
+ type = 0x3;
+ break;
+ default:
+ return 0; /* unsupported breakpoint type */
+ }
+
+ /* Only lengths 1, 2, and 4 are supported */
+ if ( len != 2 && len != 4 ) {
+ len = 1;
+ }
+ len--; /* convert to x86 breakpoint length bit pattern */
+
+ /* Set up the breakpoint */
+ bp = gdbmach_find_hwbp ( type, addr, len );
+ if ( !bp ) {
+ return 0; /* ran out of hardware breakpoints */
+ }
+ bp->type = type;
+ bp->addr = addr;
+ bp->len = len;
+ bp->enabled = enable;
+ gdbmach_commit_hwbp ( bp );
+ return 1;
+}
+
+static void gdbmach_disable_hwbps ( void ) {
+ /* Store and clear hardware breakpoints */
+ __asm__ __volatile__ ( "movl %0, %%dr7\n" : : "r" ( DR7_CLEAR ) );
+}
+
+static void gdbmach_enable_hwbps ( void ) {
+ /* Clear breakpoint status register */
+ __asm__ __volatile__ ( "movl %0, %%dr6\n" : : "r" ( DR6_CLEAR ) );
+
+ /* Restore hardware breakpoints */
+ __asm__ __volatile__ ( "movl %0, %%dr7\n" : : "r" ( dr7 ) );
+}
+
+/* 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 void serial_write ( void *buf, size_t len ) {
+ char *p = buf;
+ while ( len-- > 0 )
+ serial_putc ( *p++ );
+}
+
+static uint8_t gdbstub_from_hex_digit ( char ch ) {
+ if ( ch >= '0' && ch <= '9' )
+ return ch - '0';
+ else if ( ch >= 'A' && ch <= 'F' )
+ return ch - 'A' + 0xa;
+ else
+ return ( ch - 'a' + 0xa ) & 0xf;
+}
+
+static uint8_t gdbstub_to_hex_digit ( uint8_t b ) {
+ b &= 0xf;
+ return ( b < 0xa ? '0' : 'a' - 0xa ) + b;
+}
+
+/*
+ * To make reading/writing device memory atomic, we check for
+ * 2- or 4-byte aligned operations and handle them specially.
+ */
+
+static void gdbstub_from_hex_buf ( char *dst, char *src, int lenbytes ) {
+ if ( lenbytes == 2 && ( ( unsigned long ) dst & 0x1 ) == 0 ) {
+ uint16_t i = gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
+ gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
+ gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
+ gdbstub_from_hex_digit ( src [ 1 ] );
+ * ( uint16_t * ) dst = i;
+ } else if ( lenbytes == 4 && ( ( unsigned long ) dst & 0x3 ) == 0 ) {
+ uint32_t i = gdbstub_from_hex_digit ( src [ 6 ] ) << 28 |
+ gdbstub_from_hex_digit ( src [ 7 ] ) << 24 |
+ gdbstub_from_hex_digit ( src [ 4 ] ) << 20 |
+ gdbstub_from_hex_digit ( src [ 5 ] ) << 16 |
+ gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
+ gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
+ gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
+ gdbstub_from_hex_digit ( src [ 1 ] );
+ * ( uint32_t * ) dst = i;
+ } else {
+ while ( lenbytes-- > 0 ) {
+ *dst++ = gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
+ gdbstub_from_hex_digit ( src [ 1 ] );
+ src += 2;
+ }
+ }
+}
+
+static void gdbstub_to_hex_buf ( char *dst, char *src, int lenbytes ) {
+ if ( lenbytes == 2 && ( ( unsigned long ) src & 0x1 ) == 0 ) {
+ uint16_t i = * ( uint16_t * ) src;
+ dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 );
+ dst [ 1 ] = gdbstub_to_hex_digit ( i );
+ dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 );
+ dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 );
+ } else if ( lenbytes == 4 && ( ( unsigned long ) src & 0x3 ) == 0 ) {
+ uint32_t i = * ( uint32_t * ) src;
+ dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 );
+ dst [ 1 ] = gdbstub_to_hex_digit ( i );
+ dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 );
+ dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 );
+ dst [ 4 ] = gdbstub_to_hex_digit ( i >> 20 );
+ dst [ 5 ] = gdbstub_to_hex_digit ( i >> 16);
+ dst [ 6 ] = gdbstub_to_hex_digit ( i >> 28 );
+ dst [ 7 ] = gdbstub_to_hex_digit ( i >> 24 );
+ } else {
+ while ( lenbytes-- > 0 ) {
+ *dst++ = gdbstub_to_hex_digit ( *src >> 4 );
+ *dst++ = gdbstub_to_hex_digit ( *src );
+ src++;
+ }
+ }
+}
+
+static uint8_t gdbstub_cksum ( char *data, int len ) {
+ uint8_t cksum = 0;
+ while ( len-- > 0 ) {
+ cksum += ( uint8_t ) *data++;
+ }
+ return cksum;
+}
+
+static void gdbstub_tx_packet ( struct gdbstub *stub ) {
+ uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len );
+ stub->buf [ 0 ] = '$';
+ stub->buf [ stub->len + 1 ] = '#';
+ stub->buf [ stub->len + 2 ] = gdbstub_to_hex_digit ( cksum >> 4 );
+ stub->buf [ stub->len + 3 ] = gdbstub_to_hex_digit ( cksum );
+ serial_write ( stub->buf, stub->len + 4 );
+ 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 ], GDBMACH_SIZEOF_REGS );
+ 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_PAYLOAD / 2 ) ? args [ 1 ] : SIZEOF_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 ) / 2 );
+ 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, (unsigned long *)&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_breakpoint ( struct gdbstub *stub ) {
+ unsigned long args [ 3 ];
+ int enable = stub->payload [ 0 ] == 'Z' ? 1 : 0;
+ if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
+ gdbstub_send_errno ( stub, POSIX_EINVAL );
+ return;
+ }
+ if ( gdbmach_set_breakpoint ( args [ 0 ], args [ 1 ], args [ 2 ], enable ) ) {
+ gdbstub_send_ok ( stub );
+ } else {
+ /* Not supported */
+ stub->len = 0;
+ gdbstub_tx_packet ( stub );
+ }
+}
+
+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': /* Continue */
+ case 'k': /* Kill */
+ case 's': /* Step */
+ case 'D': /* Detach */
+ gdbstub_continue ( stub, stub->payload [ 0 ] == 's' );
+ if ( stub->payload [ 0 ] == 'D' ) {
+ gdbstub_send_ok ( stub );
+ }
+ break;
+ case 'Z': /* Insert breakpoint */
+ case 'z': /* Remove breakpoint */
+ gdbstub_breakpoint ( stub );
+ 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 < SIZEOF_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 ) {
+ serial_write ( "+", 1 );
+ if ( stub->len > 0 ) {
+ gdbstub_rx_packet ( stub );
+ }
+ } else {
+ serial_write ( "-", 1 );
+ }
+}
+
+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 */
+ } else if ( ch == '$' ) {
+ /* GDB is reconnecting, drop our packet and listen to GDB */
+ serial_write ( "-", 1 );
+ stub->parse = gdbstub_state_new;
+ }
+}
+
+void gdbstub_handler ( int signo, gdbreg_t *regs ) {
+ struct gdbstub stub;
+
+ gdbmach_disable_hwbps();
+
+ stub.parse = gdbstub_state_new;
+ stub.payload = &stub.buf [ 1 ];
+ stub.signo = signo;
+ stub.regs = regs;
+ stub.exit_handler = 0;
+ gdbstub_report_signal ( &stub );
+ while ( !stub.exit_handler )
+ stub.parse ( &stub, serial_getc() );
+
+ gdbmach_enable_hwbps();
+}