/*
* 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.
*/
#include <stddef.h>
#include <stdio.h>
#include <assert.h>
#include <gpxe/uaccess.h>
#include <gpxe/gdbstub.h>
#include <gdbmach.h>
/** @file
*
* GDB architecture-specific bits for i386
*
*/
enum {
DR7_CLEAR = 0x00000400, /* disable hardware breakpoints */
DR6_CLEAR = 0xffff0ff0, /* clear breakpoint status */
};
/** 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 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 ) {
unsigned int regnum = bp - hwbps;
/* Set breakpoint address */
assert ( regnum < ( sizeof hwbps / sizeof hwbps [ 0 ] ) );
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 */
/* Calculate linear address by adding segment base */
addr += virt_offset;
/* 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 ) );
}
__asmcall void gdbmach_handler ( int signo, gdbreg_t *regs ) {
gdbmach_disable_hwbps();
gdbstub_handler ( signo, regs );
gdbmach_enable_hwbps();
}
