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authorStefan Hajnoczi <stefanha@gmail.com>2008-08-29 15:08:26 +0100
committerStefan Hajnoczi <stefanha@gmail.com>2008-08-29 15:08:26 +0100
commit77950e64a458e753900ff4ff6119bea15d1a4533 (patch)
tree3d00561537edc658061392b2e8400f21ececdd85
parent968a89b1417d24e3247c96950b434de1971b0d4e (diff)
downloadsyslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.tar.gz
syslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.tar.xz
syslinux.git-77950e64a458e753900ff4ff6119bea15d1a4533.zip
Add GDB stub
-rw-r--r--com32/gdbstub/Makefile2
-rw-r--r--com32/gdbstub/gdbstub.c531
-rw-r--r--com32/gdbstub/int.S77
-rw-r--r--com32/gdbstub/main.c76
-rw-r--r--com32/gdbstub/serial.c190
-rw-r--r--com32/gdbstub/serial.h14
6 files changed, 874 insertions, 16 deletions
diff --git a/com32/gdbstub/Makefile b/com32/gdbstub/Makefile
index d9e55c8c..c5b79ead 100644
--- a/com32/gdbstub/Makefile
+++ b/com32/gdbstub/Makefile
@@ -25,7 +25,7 @@ LNXLIBS = ../libutil/libutil_lnx.a
MODULES = gdbstub.c32
TESTFILES =
-OBJS = main.o
+OBJS = main.o int.o serial.o gdbstub.o
all: $(MODULES) $(TESTFILES)
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();
+}
diff --git a/com32/gdbstub/int.S b/com32/gdbstub/int.S
new file mode 100644
index 00000000..2a1ff9dd
--- /dev/null
+++ b/com32/gdbstub/int.S
@@ -0,0 +1,77 @@
+ .section ".text","ax"
+
+#define SIGTRAP 5
+
+#define SIZEOF_I386_REGS 32
+#define SIZEOF_I386_FLAGS 4
+
+/* When invoked, the stack contains: eflags, cs, eip, signo. */
+#define IH_OFFSET_GDB_REGS ( 0 )
+#define IH_OFFSET_GDB_EIP ( IH_OFFSET_GDB_REGS + SIZEOF_I386_REGS )
+#define IH_OFFSET_GDB_EFLAGS ( IH_OFFSET_GDB_EIP + 4 )
+#define IH_OFFSET_GDB_SEG_REGS ( IH_OFFSET_GDB_EFLAGS + SIZEOF_I386_FLAGS )
+#define IH_OFFSET_GDB_END ( IH_OFFSET_GDB_SEG_REGS + 6 * 4 )
+#define IH_OFFSET_OLD_EIP ( IH_OFFSET_GDB_END )
+#define IH_OFFSET_OLD_CS ( IH_OFFSET_OLD_EIP + 4 )
+#define IH_OFFSET_OLD_EFLAGS ( IH_OFFSET_OLD_CS + 4 )
+#define IH_OFFSET_END ( IH_OFFSET_OLD_EFLAGS + 4 )
+
+/* We also access the stack whilst still storing or restoring
+ * the register snapshot. Since ESP is in flux, we need
+ * special offsets.
+ */
+#define IH_OFFSET_FLUX_OLD_CS ( IH_OFFSET_OLD_CS - 44 )
+#define IH_OFFSET_FLUX_OLD_EFLAGS ( IH_OFFSET_OLD_EFLAGS - 40 )
+#define IH_OFFSET_FLUX_OLD_EIP ( IH_OFFSET_OLD_EIP - 36 )
+#define IH_OFFSET_FLUX_END ( IH_OFFSET_END - 20 )
+
+ .global int_handler
+int_handler:
+ /* Store CPU state in GDB register snapshot */
+ pushw $0
+ pushw %gs
+ pushw $0
+ pushw %fs
+ pushw $0
+ pushw %es
+ pushw $0
+ pushw %ds
+ pushw $0
+ pushw %ss
+ pushw $0
+ pushw IH_OFFSET_FLUX_OLD_CS + 2(%esp)
+ pushl IH_OFFSET_FLUX_OLD_EFLAGS(%esp)
+ pushl IH_OFFSET_FLUX_OLD_EIP(%esp)
+ pushl %edi
+ pushl %esi
+ pushl %ebp
+ leal IH_OFFSET_FLUX_END(%esp), %edi
+ pushl %edi /* old ESP */
+ pushl %ebx
+ pushl %edx
+ pushl %ecx
+ pushl %eax
+
+ /* Call GDB stub exception handler */
+ movl $SIGTRAP, %eax
+ movl %esp, %edx
+ call gdbstub_handler
+
+ /* Restore CPU state from GDB register snapshot */
+ popl %eax
+ popl %ecx
+ popl %edx
+ popl %ebx
+ addl $4, %esp /* Changing ESP currently not supported */
+ popl %ebp
+ popl %esi
+ popl %edi
+ popl IH_OFFSET_FLUX_OLD_EIP(%esp)
+ popl IH_OFFSET_FLUX_OLD_EFLAGS(%esp)
+ popl IH_OFFSET_FLUX_OLD_CS(%esp)
+ popl %ss
+ popl %ds
+ popl %es
+ popl %fs
+ popl %gs
+ iret
diff --git a/com32/gdbstub/main.c b/com32/gdbstub/main.c
index 11c4e08b..8bb1dc5e 100644
--- a/com32/gdbstub/main.c
+++ b/com32/gdbstub/main.c
@@ -4,15 +4,44 @@
#include <console.h>
#include <com32.h>
#include <syslinux/loadfile.h>
+#include "serial.h"
+#define X86_INT_DB 1
+#define X86_INT_BP 3
+#define COM32_IDT ((void*)0x100000)
#define COM32_LOAD_ADDR ((void*)0x101000)
-#define STACK_RED_ZONE 0x1000
+#define STACK_SIZE 0x1000
+
+extern char _start[], _end[];
+
+struct reloc_info {
+ void *data;
+ size_t len;
+ uint32_t old_esp;
+ uint32_t reloc_base;
+};
static inline void error(const char *msg)
{
fputs(msg, stderr);
}
+static inline uint32_t reloc_ptr(struct reloc_info *ri, void *ptr)
+{
+ return ri->reloc_base + (uint32_t)((char*)ptr - _start);
+}
+
+static void hijack_interrupt(int intn, uint32_t handler)
+{
+ struct {
+ uint32_t lo;
+ uint32_t hi;
+ } *idt = COM32_IDT;
+
+ idt[intn].lo = (idt[intn].lo & 0xffff0000) | (handler & 0x0000ffff);
+ idt[intn].hi = (idt[intn].hi & 0x0000ffff) | (handler & 0xffff0000);
+}
+
static void shift_cmdline(struct com32_sys_args *com32)
{
char *p;
@@ -32,52 +61,67 @@ static void shift_cmdline(struct com32_sys_args *com32)
com32->cs_cmdline = p;
}
-static __noreturn reloc_entry(void *ptr, size_t len, uintptr_t entry_esp, uintptr_t module_esp)
+static __noreturn reloc_entry(struct reloc_info *ri)
{
+ extern char int_handler[];
size_t stack_frame_size = sizeof(struct com32_sys_args) + 4;
struct com32_sys_args *com32;
+ uint32_t module_esp;
+
+ hijack_interrupt(X86_INT_DB, reloc_ptr(ri, int_handler));
+ hijack_interrupt(X86_INT_BP, reloc_ptr(ri, int_handler));
/* Copy module to load address */
- memcpy(COM32_LOAD_ADDR, ptr, len);
+ memcpy(COM32_LOAD_ADDR, ri->data, ri->len);
/* Copy stack frame onto module stack */
- module_esp = (module_esp - stack_frame_size) & ~15;
- memcpy((void*)module_esp, (void*)entry_esp, stack_frame_size);
+ module_esp = (ri->reloc_base - stack_frame_size) & ~15;
+ memcpy((void*)module_esp, (void*)ri->old_esp, stack_frame_size);
/* Fix up command line */
- com32 = (struct com32_sys_args*)((char*)module_esp + 4);
+ com32 = (struct com32_sys_args*)(module_esp + 4);
shift_cmdline(com32);
- /* Invoke module with stack set up */
+ /* Set up CPU state to run module and enter GDB */
asm volatile (
"movl %0, %%esp\n\t"
- "jmp *%%ecx"
- : : "r"(module_esp), "c"(COM32_LOAD_ADDR)
+ "pushf\n\t"
+ "pushl %%cs\n\t"
+ "pushl %1\n\t"
+ "jmp *%2\n\t"
+ : : "r"(module_esp),
+ "c"(COM32_LOAD_ADDR),
+ "r"(reloc_ptr(ri, int_handler))
);
for(;;); /* shut the compiler up */
}
static inline __noreturn reloc(void *ptr, size_t len)
{
- extern uintptr_t __entry_esp;
- extern char _start[], _end[];
+ extern uint32_t __entry_esp;
size_t total_size = _end - _start;
- __noreturn (*success_fn)(void*, size_t, uintptr_t, uintptr_t);
+ __noreturn (*entry_fn)(struct reloc_info*);
+ struct reloc_info ri;
uint32_t esp;
char *dest;
/* Calculate relocation address, preserve current stack */
asm volatile ("movl %%esp, %0\n\t" : "=m"(esp));
- dest = (char*)((esp - STACK_RED_ZONE - total_size) & ~3);
+ dest = (char*)((esp - STACK_SIZE - total_size) & ~3);
/* Calculate entry point in relocated code */
- success_fn = (void*)(dest + ((char*)reloc_entry - _start));
+ entry_fn = (void*)(dest + ((char*)reloc_entry - _start));
/* Copy all sections to relocation address */
printf("Relocating %d bytes from %p to %p\n", total_size, _start, dest);
memcpy(dest, _start, total_size);
- success_fn(ptr, len, __entry_esp, (uintptr_t)dest);
+ /* Call into relocated code */
+ ri.data = ptr;
+ ri.len = len;
+ ri.old_esp = __entry_esp;
+ ri.reloc_base = (uint32_t)dest;
+ entry_fn(&ri);
}
int main(int argc, char *argv[])
@@ -97,6 +141,8 @@ int main(int argc, char *argv[])
return 1;
}
+ serial_init();
+
/* No more lib calls after this point */
reloc(data, data_len);
}
diff --git a/com32/gdbstub/serial.c b/com32/gdbstub/serial.c
new file mode 100644
index 00000000..1c4d4b6f
--- /dev/null
+++ b/com32/gdbstub/serial.c
@@ -0,0 +1,190 @@
+/*
+ * The serial port interface routines implement a simple polled i/o
+ * interface to a standard serial port. Due to the space restrictions
+ * for the boot blocks, no BIOS support is used (since BIOS requires
+ * expensive real/protected mode switches), instead the rudimentary
+ * BIOS support is duplicated here.
+ *
+ * The base address and speed for the i/o port are passed from the
+ * Makefile in the COMCONSOLE and CONSPEED preprocessor macros. The
+ * line control parameters are currently hard-coded to 8 bits, no
+ * parity, 1 stop bit (8N1). This can be changed in init_serial().
+ */
+
+#include <stddef.h>
+#include <sys/io.h>
+#include "serial.h"
+
+/* Set default values if none specified */
+
+#ifndef COMCONSOLE
+#define COMCONSOLE 0x3f8
+#endif
+
+#ifndef COMSPEED
+#define COMSPEED 9600
+#endif
+
+#ifndef COMDATA
+#define COMDATA 8
+#endif
+
+#ifndef COMPARITY
+#define COMPARITY 0
+#endif
+
+#ifndef COMSTOP
+#define COMSTOP 1
+#endif
+
+#undef UART_BASE
+#define UART_BASE ( COMCONSOLE )
+
+#undef UART_BAUD
+#define UART_BAUD ( COMSPEED )
+
+#if ((115200%UART_BAUD) != 0)
+#error Bad ttys0 baud rate
+#endif
+
+#define COMBRD (115200/UART_BAUD)
+
+/* Line Control Settings */
+#define UART_LCS ( ( ( (COMDATA) - 5 ) << 0 ) | \
+ ( ( (COMPARITY) ) << 3 ) | \
+ ( ( (COMSTOP) - 1 ) << 2 ) )
+
+/* Data */
+#define UART_RBR 0x00
+#define UART_TBR 0x00
+
+/* Control */
+#define UART_IER 0x01
+#define UART_IIR 0x02
+#define UART_FCR 0x02
+#define UART_LCR 0x03
+#define UART_MCR 0x04
+#define UART_DLL 0x00
+#define UART_DLM 0x01
+
+/* Status */
+#define UART_LSR 0x05
+#define UART_LSR_TEMPT 0x40 /* Transmitter empty */
+#define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
+#define UART_LSR_BI 0x10 /* Break interrupt indicator */
+#define UART_LSR_FE 0x08 /* Frame error indicator */
+#define UART_LSR_PE 0x04 /* Parity error indicator */
+#define UART_LSR_OE 0x02 /* Overrun error indicator */
+#define UART_LSR_DR 0x01 /* Receiver data ready */
+
+#define UART_MSR 0x06
+#define UART_SCR 0x07
+
+#define uart_readb(addr) inb(addr)
+#define uart_writeb(val,addr) outb((val),(addr))
+
+/*
+ * void serial_putc(int ch);
+ * Write character `ch' to port UART_BASE.
+ */
+void serial_putc ( int ch ) {
+ int status;
+ for (;;) {
+ status = uart_readb(UART_BASE + UART_LSR);
+ if (status & UART_LSR_THRE) {
+ /* TX buffer emtpy */
+ uart_writeb(ch, UART_BASE + UART_TBR);
+ break;
+ }
+ }
+}
+
+/*
+ * int serial_getc(void);
+ * Read a character from port UART_BASE.
+ */
+int serial_getc ( void ) {
+ int status;
+ int ch;
+ do {
+ status = uart_readb(UART_BASE + UART_LSR);
+ } while((status & 1) == 0);
+ ch = uart_readb(UART_BASE + UART_RBR); /* fetch (first) character */
+ ch &= 0x7f; /* remove any parity bits we get */
+ if (ch == 0x7f) { /* Make DEL... look like BS */
+ ch = 0x08;
+ }
+ return ch;
+}
+
+/*
+ * int serial_init(void);
+ * Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
+ */
+void serial_init ( void ) {
+ int status;
+ int divisor, lcs;
+
+ divisor = COMBRD;
+ lcs = UART_LCS;
+
+
+#ifdef COMPRESERVE
+ lcs = uart_readb(UART_BASE + UART_LCR) & 0x7f;
+ uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
+ divisor = (uart_readb(UART_BASE + UART_DLM) << 8) | uart_readb(UART_BASE + UART_DLL);
+ uart_writeb(lcs, UART_BASE + UART_LCR);
+#endif
+
+ /* Set Baud Rate Divisor to COMSPEED, and test to see if the
+ * serial port appears to be present.
+ */
+ uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
+ uart_writeb(0xaa, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != 0xaa) {
+ goto out;
+ }
+ uart_writeb(0x55, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
+ goto out;
+ }
+ uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
+ if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
+ goto out;
+ }
+ uart_writeb(0xaa, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
+ goto out;
+ }
+ uart_writeb(0x55, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
+ goto out;
+ }
+ uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
+ if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
+ goto out;
+ }
+ uart_writeb(lcs, UART_BASE + UART_LCR);
+
+ /* disable interrupts */
+ uart_writeb(0x0, UART_BASE + UART_IER);
+
+ /* disable fifo's */
+ uart_writeb(0x00, UART_BASE + UART_FCR);
+
+ /* Set clear to send, so flow control works... */
+ uart_writeb((1<<1), UART_BASE + UART_MCR);
+
+
+ /* Flush the input buffer. */
+ do {
+ /* rx buffer reg
+ * throw away (unconditionally the first time)
+ */
+ (void) uart_readb(UART_BASE + UART_RBR);
+ /* line status reg */
+ status = uart_readb(UART_BASE + UART_LSR);
+ } while(status & UART_LSR_DR);
+ out:
+ return;
+}
diff --git a/com32/gdbstub/serial.h b/com32/gdbstub/serial.h
new file mode 100644
index 00000000..c78a5757
--- /dev/null
+++ b/com32/gdbstub/serial.h
@@ -0,0 +1,14 @@
+#ifndef _GPXE_SERIAL_H
+#define _GPXE_SERIAL_H
+
+/** @file
+ *
+ * Serial driver functions
+ *
+ */
+
+extern void serial_putc ( int ch );
+extern int serial_getc ( void );
+extern void serial_init ( void );
+
+#endif /* _GPXE_SERIAL_H */