--- /dev/null
+#include <stddef.h>
+#include <stdio.h>
+#include <assert.h>
+#include <virtaddr.h>
+#include <gpxe/gdbstub.h>
+#include <gdbmach.h>
+
+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 gdbreg_t dr6;
+
+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 */
+ assert ( regnum >= 0 && 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 breakpoint status register */
+ __asm__ __volatile__ ( "movl %%dr6, %0\n" "movl %1, %%dr6\n" : "=r" ( dr6 ) : "r" ( DR6_CLEAR ) );
+
+ /* Store and clear hardware breakpoints */
+ __asm__ __volatile__ ( "movl %0, %%dr7\n" : : "r" ( DR7_CLEAR ) );
+}
+
+static void gdbmach_enable_hwbps ( void ) {
+ /* Restore hardware breakpoints */
+ __asm__ __volatile__ ( "movl %0, %%dr7\n" : : "r" ( dr7 ) );
+}
+
+__cdecl void gdbmach_handler ( int signo, gdbreg_t *regs ) {
+ gdbmach_disable_hwbps();
+ gdbstub_handler ( signo, regs );
+ gdbmach_enable_hwbps();
+}
/* 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_send_ok ( stub );
}
break;
+ case 'Z': /* Insert breakpoint */
+ case 'z': /* Remove breakpoint */
+ gdbstub_breakpoint ( stub );
+ break;
default:
stub->len = 0;
gdbstub_tx_packet ( stub );
.parse = gdbstub_state_new
};
-__cdecl void gdbstub_handler ( int signo, gdbreg_t *regs ) {
+void gdbstub_handler ( int signo, gdbreg_t *regs ) {
char packet [ SIZEOF_PAYLOAD + 4 ];
size_t len, i;