[PATCH v2 6/6] cpukit/libdebugger: Add MicroBlaze support

Kinsey Moore kinsey.moore at oarcorp.com
Fri Feb 18 16:57:33 UTC 2022


Add MicroBlaze support for libdebugger. This uses only software break
type instructions to provide self-hosted GDB debugging support for
applications since internal control of debug hardware is not possible.

Also of note, this implementation for MicroBlaze would typically use the
brki instruction for software break, but instead uses an illegal opcode
to manage software breaks as exceptions. This is due to poor interaction
with the debug hardware where the debug hardware will intercept software
breaks instead of allowing the software break vector to execute.
---
 .../libdebugger/rtems-debugger-microblaze.c   | 1462 +++++++++++++++++
 .../cpu/microblaze/include/rtems/score/cpu.h  |   24 +
 spec/build/cpukit/libdebugger.yml             |    2 +
 spec/build/cpukit/objdbgmicroblaze.yml        |   15 +
 spec/build/cpukit/optlibdebugger.yml          |    1 +
 5 files changed, 1504 insertions(+)
 create mode 100644 cpukit/libdebugger/rtems-debugger-microblaze.c
 create mode 100644 spec/build/cpukit/objdbgmicroblaze.yml

diff --git a/cpukit/libdebugger/rtems-debugger-microblaze.c b/cpukit/libdebugger/rtems-debugger-microblaze.c
new file mode 100644
index 0000000000..13b43b287b
--- /dev/null
+++ b/cpukit/libdebugger/rtems-debugger-microblaze.c
@@ -0,0 +1,1462 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/**
+ * @file
+ *
+ * @ingroup RTEMSLibdebugger
+ *
+ * @brief MicroBlaze libdebugger implementation
+ */
+
+/*
+ * Copyright (C) 2022 On-Line Applications Research Corporation (OAR)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define TARGET_DEBUG 0
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <errno.h>
+#include <inttypes.h>
+#include <stdlib.h>
+
+/* Defined by linkcmds.base */
+extern char bsp_section_text_begin[];
+extern char bsp_section_text_end[];
+extern char bsp_section_fast_text_begin[];
+extern char bsp_section_fast_text_end[];
+
+#include <rtems.h>
+#include <rtems/score/cpu.h>
+#include <rtems/score/threadimpl.h>
+#include <rtems/score/userextimpl.h>
+
+#include <rtems/debugger/rtems-debugger-bsp.h>
+
+#include "rtems-debugger-target.h"
+#include "rtems-debugger-threads.h"
+
+#if TARGET_DEBUG
+#include <rtems/bspIo.h>
+#endif
+
+/*
+ * Number of registers.
+ */
+#define RTEMS_DEBUGGER_NUMREGS 57
+
+/*
+ * Number of bytes per type of register.
+ */
+#define RTEMS_DEBUGGER_REG_BYTES    4
+
+/* Debugger registers layout. See microblaze-core.xml in GDB source. */
+#define REG_R0    0
+#define REG_R1    1
+#define REG_R2    2
+#define REG_R3    3
+#define REG_R4    4
+#define REG_R5    5
+#define REG_R6    6
+#define REG_R7    7
+#define REG_R8    8
+#define REG_R9    9
+#define REG_R10   10
+#define REG_R11   11
+#define REG_R12   12
+#define REG_R13   13
+#define REG_R14   14
+#define REG_R15   15
+#define REG_R16   16
+#define REG_R17   17
+#define REG_R18   18
+#define REG_R19   19
+#define REG_R20   20
+#define REG_R21   21
+#define REG_R22   22
+#define REG_R23   23
+#define REG_R24   24
+#define REG_R25   25
+#define REG_R26   26
+#define REG_R27   27
+#define REG_R28   28
+#define REG_R29   29
+#define REG_R30   30
+#define REG_R31   31
+#define REG_PC    32
+#define REG_MS    33
+#define REG_EA    34
+#define REG_ES    35
+#define REG_FS    36
+#define REG_BT    37
+#define REG_PV0   38
+#define REG_PV1   39
+#define REG_PV2   40
+#define REG_PV3   41
+#define REG_PV4   42
+#define REG_PV5   43
+#define REG_PV6   44
+#define REG_PV7   45
+#define REG_PV8   46
+#define REG_PV9   47
+#define REG_PV10  48
+#define REG_PV11  49
+#define REG_ED    50
+#define REG_PID   51
+#define REG_ZP    52
+#define REG_TBLX  53
+#define REG_TBLSX 54
+#define REG_TBLLO 55
+#define REG_TBLHI 56
+
+/**
+ * Register offset table with the total as the last entry.
+ *
+ * Check this table in gdb with the command:
+ *
+ *   maint print registers
+ */
+static const size_t microblaze_reg_offsets[ RTEMS_DEBUGGER_NUMREGS + 1 ] = {
+  REG_R0 * 4,
+  REG_R1 * 4,
+  REG_R2 * 4,
+  REG_R3 * 4,
+  REG_R4 * 4,
+  REG_R5 * 4,
+  REG_R6 * 4,
+  REG_R7 * 4,
+  REG_R8 * 4,
+  REG_R9 * 4,
+  REG_R10 * 4,
+  REG_R11 * 4,
+  REG_R12 * 4,
+  REG_R13 * 4,
+  REG_R14 * 4,
+  REG_R15 * 4,
+  REG_R16 * 4,
+  REG_R17 * 4,
+  REG_R18 * 4,
+  REG_R19 * 4,
+  REG_R20 * 4,
+  REG_R21 * 4,
+  REG_R22 * 4,
+  REG_R23 * 4,
+  REG_R24 * 4,
+  REG_R25 * 4,
+  REG_R26 * 4,
+  REG_R27 * 4,
+  REG_R28 * 4,
+  REG_R29 * 4,
+  REG_R30 * 4,
+  REG_R31 * 4,
+  REG_PC * 4,
+  REG_MS * 4,
+  REG_EA * 4,
+  REG_ES * 4,
+  REG_FS * 4,
+  REG_BT * 4,
+  REG_PV0 * 4,
+  REG_PV1 * 4,
+  REG_PV2 * 4,
+  REG_PV3 * 4,
+  REG_PV4 * 4,
+  REG_PV5 * 4,
+  REG_PV6 * 4,
+  REG_PV7 * 4,
+  REG_PV8 * 4,
+  REG_PV9 * 4,
+  REG_PV10 * 4,
+  REG_PV11 * 4,
+  REG_ED * 4,
+  REG_PID * 4,
+  REG_ZP * 4,
+  REG_TBLX * 4,
+  REG_TBLSX * 4,
+  REG_TBLLO * 4,
+  REG_TBLHI * 4,
+/* Total size */
+  REG_TBLHI * 4 + 4,
+};
+
+/*
+ * Number of bytes of registers.
+ */
+#define RTEMS_DEBUGGER_NUMREGBYTES \
+  microblaze_reg_offsets[ RTEMS_DEBUGGER_NUMREGS ]
+
+/**
+ * Print the exception frame.
+ */
+#define EXC_FRAME_PRINT( _out, _prefix, _frame ) \
+  do { \
+    _out( \
+      _prefix "  R0 = 0x%08" PRIx32 "  R1 = 0x%08" PRIx32 \
+      "  R2 = 0x%08" PRIx32 "  R3 = 0x%08" PRIx32 "\n", \
+      0, \
+      _frame->r1, \
+      _frame->r2, \
+      _frame->r3 \
+    ); \
+    _out( \
+      _prefix "  R4 = 0x%08" PRIx32 "  R5 = 0x%08" PRIx32 \
+      "  R6 = 0x%08" PRIx32 "  R7 = 0x%08" PRIx32 "\n", \
+      _frame->r4, \
+      _frame->r5, \
+      _frame->r6, \
+      _frame->r7 \
+    ); \
+    _out( \
+      _prefix "  R8 = 0x%08" PRIx32 "  R9 = 0x%08" PRIx32 \
+      " R10 = 0x%08" PRIx32 " R11 = 0x%08" PRIx32 "\n", \
+      _frame->r8, \
+      _frame->r9, \
+      _frame->r10, \
+      _frame->r11 \
+    ); \
+    _out( \
+      _prefix " R12 = 0x%08" PRIx32 " R13 = 0x%08" PRIx32 \
+      " R14 = 0x%08" PRIxPTR " R15 = 0x%08" PRIxPTR "\n", \
+      _frame->r12, \
+      _frame->r13, \
+      (uintptr_t) _frame->r14, \
+      (uintptr_t) _frame->r15 \
+    ); \
+    _out( \
+      _prefix " R16 = 0x%08" PRIxPTR " R17 = 0x%08" PRIxPTR \
+      " R18 = 0x%08" PRIx32 " R19 = 0x%08" PRIx32 "\n", \
+      (uintptr_t) _frame->r16, \
+      (uintptr_t) _frame->r17, \
+      _frame->r18, \
+      _frame->r19 \
+    ); \
+    _out( \
+      _prefix " R20 = 0x%08" PRIx32 " R21 = 0x%08" PRIx32 \
+      " R22 = 0x%08" PRIx32 " R23 = 0x%08" PRIx32 "\n", \
+      _frame->r20, \
+      _frame->r21, \
+      _frame->r22, \
+      _frame->r23 \
+    ); \
+    _out( \
+      _prefix " R24 = 0x%08" PRIx32 " R25 = 0x%08" PRIx32 \
+      " R26 = 0x%08" PRIx32 " R27 = 0x%08" PRIx32 "\n", \
+      _frame->r24, \
+      _frame->r25, \
+      _frame->r26, \
+      _frame->r27 \
+    ); \
+    _out( \
+      _prefix " R28 = 0x%08" PRIx32 " R29 = 0x%08" PRIx32 \
+      " R30 = 0x%08" PRIxPTR " R31 = 0x%08" PRIxPTR "\n", \
+      _frame->r28, \
+      _frame->r29, \
+      _frame->r30, \
+      _frame->r31 \
+    ); \
+    _out( \
+      _prefix " EAR = %p ESR = 0x%08" PRIx32 "\n", \
+      _frame->ear, \
+      _frame->esr \
+    ); \
+    _out( \
+      _prefix "  PC = %p\n", \
+      _frame->r16 \
+    ); \
+    _out( \
+      _prefix " MSR = 0x%08" PRIx32 " En:%c%c%c%c Prog:%c%c%c Mode:%c%c Arith:%c%c\n", \
+      _frame->msr, \
+      ( _frame->msr & MICROBLAZE_MSR_IE ) != 0 ? 'I' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_ICE ) != 0 ? 'C' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_DCE ) != 0 ? 'D' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_EE ) != 0 ? 'E' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_BIP ) != 0 ? 'B' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_FSL ) != 0 ? 'F' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_EIP ) != 0 ? 'E' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_UM ) != 0 ? 'U' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_VM ) != 0 ? 'V' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_C ) != 0 ? 'C' : '-', \
+      ( _frame->msr & MICROBLAZE_MSR_DZO ) != 0 ? 'Z' : '-' \
+    ); \
+  } while ( 0 )
+
+/**
+ * The breakpoint instruction can be intercepted on hardware by an active JTAG
+ * connection. This instead uses an illegal opcode (0xdeadbeef) to trigger an
+ * exception as a mechanism to call into the debugger.
+ */
+static const uint8_t breakpoint[ 4 ] = { 0xef, 0xbe, 0xad, 0xde };
+
+/**
+ * Target lock.
+ */
+RTEMS_INTERRUPT_LOCK_DEFINE( static, target_lock, "target_lock" )
+
+/**
+ * Is a session active?
+ */
+static bool debug_session_active;
+
+/*
+ * MicroBlaze debug hardware.
+ */
+static uint8_t hw_breakpoints;
+static uint8_t hw_read_watchpoints;
+static uint8_t hw_write_watchpoints;
+
+/* Software breakpoints for single stepping */
+typedef struct {
+  uint32_t *address;
+} microblaze_soft_step;
+
+microblaze_soft_step next_soft_break = { 0 };
+microblaze_soft_step target_soft_break = { 0 };
+
+static void set_soft_break(
+  microblaze_soft_step *soft_break,
+  uint32_t             *next_ins
+)
+{
+  soft_break->address = next_ins;
+  rtems_debugger_target_swbreak_control(
+    true,
+    (uintptr_t) soft_break->address,
+    4
+  );
+}
+
+static void restore_soft_step( microblaze_soft_step *bp )
+{
+  /*
+   * Only restore if the breakpoint is active and the instruction at the address
+   * is the breakpoint instruction.
+   */
+  if ( bp->address != NULL ) {
+    rtems_debugger_target_swbreak_control( false, (uintptr_t) bp->address, 4 );
+  }
+
+  bp->address = NULL;
+}
+
+/*
+ * Target debugging support. Use this to debug the backend.
+ */
+#if TARGET_DEBUG
+
+void rtems_debugger_printk_lock( rtems_interrupt_lock_context *lock_context );
+
+void rtems_debugger_printk_unlock(
+  rtems_interrupt_lock_context *lock_context
+);
+
+static void target_printk( const char *format, ... ) RTEMS_PRINTFLIKE( 1, 2 );
+
+static void target_printk( const char *format, ... )
+{
+  rtems_interrupt_lock_context lock_context;
+  va_list                      ap;
+
+  va_start( ap, format );
+  rtems_debugger_printk_lock( &lock_context );
+  vprintk( format, ap );
+  rtems_debugger_printk_unlock( &lock_context );
+  va_end( ap );
+}
+
+#else
+#define target_printk( _fmt, ... )
+#endif
+
+static int microblaze_debug_probe( rtems_debugger_target *target )
+{
+  uint32_t    msr;
+  uint32_t    pvr0;
+  uint32_t    pvr3;
+  const char *version = NULL;
+
+  rtems_debugger_printf(
+    "rtems-db: MicroBlaze\n"
+  );
+
+  _CPU_MSR_GET( msr );
+
+  if ( ( msr & MICROBLAZE_MSR_PVR ) == 0 ) {
+    rtems_debugger_printf(
+      "rtems-db: Processor Version Registers not supported\n"
+    );
+    return 0;
+  }
+
+  _CPU_PVR0_GET( pvr0 );
+
+  switch ( MICROBLAZE_PVR0_VERSION_GET( pvr0 ) ) {
+   case 0x1:
+     version = "v5.00.a";
+     break;
+   case 0x2:
+     version = "v5.00.b";
+     break;
+   case 0x3:
+     version = "v5.00.c";
+     break;
+   case 0x4:
+     version = "v6.00.a";
+     break;
+   case 0x5:
+     version = "v7.00.a";
+     break;
+   case 0x6:
+     version = "v6.00.b";
+     break;
+   case 0x7:
+     version = "v7.00.b";
+     break;
+   case 0x8:
+     version = "v7.10.a";
+     break;
+  }
+
+  rtems_debugger_printf(
+    "rtems-db: Version: %s (%d)\n",
+    version,
+    MICROBLAZE_PVR0_VERSION_GET( pvr0 )
+  );
+
+  /* further PVR supported? */
+  if ( ( pvr0 >> 31 ) == 0 ) {
+    rtems_debugger_printf(
+      "rtems-db: Further Processor Version Registers not supported\n"
+    );
+    return 0;
+  }
+
+  _CPU_PVR3_GET( pvr3 );
+
+  hw_breakpoints = MICROBLAZE_PVR3_BP_GET( pvr3 );
+  hw_read_watchpoints = MICROBLAZE_PVR3_RWP_GET( pvr3 );
+  hw_write_watchpoints = MICROBLAZE_PVR3_WWP_GET( pvr3 );
+
+  rtems_debugger_printf(
+    "rtems-db: breakpoints:%" PRIu32
+    " read watchpoints:%" PRIu32 " write watchpoints:%" PRIu32 "\n",
+    hw_breakpoints,
+    hw_read_watchpoints,
+    hw_write_watchpoints
+  );
+
+  return 0;
+}
+
+int rtems_debugger_target_configure( rtems_debugger_target *target )
+{
+  target->capabilities = ( RTEMS_DEBUGGER_TARGET_CAP_SWBREAK
+    | RTEMS_DEBUGGER_TARGET_CAP_PURE_SWBREAK );
+  target->reg_num = RTEMS_DEBUGGER_NUMREGS;
+  target->reg_offset = microblaze_reg_offsets;
+  target->breakpoint = &breakpoint[ 0 ];
+  target->breakpoint_size = sizeof( breakpoint );
+  return microblaze_debug_probe( target );
+}
+
+static void target_print_frame( CPU_Exception_frame *frame )
+{
+  EXC_FRAME_PRINT( target_printk, "[} ", frame );
+}
+
+/* returns true if cascade is required */
+static bool target_exception( CPU_Exception_frame *frame )
+{
+  target_print_frame( frame );
+
+  switch ( rtems_debugger_target_exception( frame ) ) {
+   case rtems_debugger_target_exc_consumed:
+   default:
+     break;
+   case rtems_debugger_target_exc_step:
+     break;
+   case rtems_debugger_target_exc_cascade:
+     target_printk( "rtems-db: unhandled exception: cascading\n" );
+     /* Continue in fatal error handler chain */
+     return true;
+  }
+
+  target_printk(
+    "[} < resuming frame = %016" PRIxPTR "\n",
+    (uintptr_t) frame
+  );
+  target_print_frame( frame );
+
+  return false;
+}
+
+static void target_exception_handler( CPU_Exception_frame *ef )
+{
+  if ( debug_session_active == false ) {
+    /* Falls into fatal error handler */
+    return;
+  }
+
+  /*
+   * Blindly roll back R17 in the exception frame due to exceptions resuming at
+   * the next instruction and not the instruction that caused the exception.
+   * TODO(kmoore): This does not apply in all cases for MicroBlaze cores that
+   *               have a MMU and can generate MMU exceptions.
+   */
+  ef->r17 = &ef->r17[ -1 ];
+
+  /*
+   * Remove single step software breakpoints since they will need to be
+   * recalculated for the current instruction.
+   */
+  restore_soft_step( &next_soft_break );
+  restore_soft_step( &target_soft_break );
+
+  /* disable all software breakpoints */
+  rtems_debugger_target_swbreak_remove();
+
+  if ( target_exception( ef ) == true ) {
+    /* Roll R17 forward for an accurate frame in the fatal error handler */
+    ef->r17 = &ef->r17[ 1 ];
+
+    /* Falls into fatal error handler */
+    return;
+  }
+
+  /* Enable all software breakpoints including added single-step breakpoints */
+  rtems_debugger_target_swbreak_insert();
+
+  /* does not return */
+  _CPU_Exception_resume( ef );
+}
+
+static void rtems_debugger_set_int_reg(
+  rtems_debugger_thread *thread,
+  size_t                 reg,
+  const uint32_t         value
+)
+{
+  const size_t offset = microblaze_reg_offsets[ reg ];
+
+  memcpy( &thread->registers[ offset ], &value, sizeof( uint32_t ) );
+}
+
+static const uint32_t rtems_debugger_get_int_reg(
+  rtems_debugger_thread *thread,
+  size_t                 reg
+)
+{
+  const size_t offset = microblaze_reg_offsets[ reg ];
+  uint32_t     value;
+
+  memcpy( &value, &thread->registers[ offset ], sizeof( uint32_t ) );
+  return value;
+}
+
+static void preint_hook( void )
+{
+  Per_CPU_Control *cpu_self = _Per_CPU_Get();
+
+  /* All software breakpoints must be disabled on entry to interrupt context */
+  if ( cpu_self->isr_nest_level != 0 ) {
+    return;
+  }
+
+  /* Handle software breaks */
+  rtems_debugger_target_swbreak_remove();
+}
+
+static bool tid_is_excluded( const rtems_id tid )
+{
+  rtems_debugger_threads *threads = rtems_debugger->threads;
+  rtems_id               *excludes;
+  size_t                  i;
+
+  excludes = rtems_debugger_thread_excludes( threads );
+
+  for ( i = 0; i < threads->excludes.level; ++i ) {
+    if ( tid == excludes[ i ] ) {
+      return true;
+    }
+  }
+
+  /* DBSe is dynamically created and destroyed, so might not actually be in the excludes list */
+  char name[ RTEMS_DEBUGGER_THREAD_NAME_SIZE ];
+
+  rtems_object_get_name( tid, sizeof( name ), (char *) &name[ 0 ] );
+
+  if ( strcmp( "DBSe", name ) == 0 ) {
+    return true;
+  }
+
+  return false;
+}
+
+static void postint_hook( void )
+{
+  Per_CPU_Control *cpu_self = _Per_CPU_Get();
+  Thread_Control  *thread = _Thread_Get_executing();
+  const rtems_id   tid = thread->Object.id;
+
+  /* All software breakpoints must be enabled on exit from interrupt context */
+  if ( cpu_self->isr_nest_level != 0 ) {
+    return;
+  }
+
+  if ( tid_is_excluded( tid ) == true ) {
+    return;
+  }
+
+  /* Insert all software breaks */
+  rtems_debugger_target_swbreak_insert();
+}
+
+static void mb_thread_switch( Thread_Control *executing, Thread_Control *heir )
+{
+  /*
+   * R13 is meant for TLS usage, but isn't used by RTEMS. It is currently being
+   * coopted as an interrupt context flag. R2 could also serve this purpose, but
+   * it would need to be added to Context_Control.
+   */
+  if ( heir->Registers.r13 != 0 ) {
+    rtems_debugger_target_swbreak_remove();
+    return;
+  }
+
+  if ( tid_is_excluded( heir->Object.id ) == true ) {
+    rtems_debugger_target_swbreak_remove();
+    return;
+  }
+
+  /* Insert all software breaks */
+  rtems_debugger_target_swbreak_insert();
+}
+
+User_extensions_Control mb_ext = {
+  .Callouts = { .thread_switch = mb_thread_switch }
+};
+
+int rtems_debugger_target_enable( void )
+{
+  debug_session_active = true;
+  rtems_interrupt_lock_context lock_context;
+
+  rtems_interrupt_lock_acquire( &target_lock, &lock_context );
+
+  _MicroBlaze_Debug_install_handler( target_exception_handler, NULL );
+  _MicroBlaze_Exception_install_handler( target_exception_handler, NULL );
+  _MicroBlaze_Pre_Interrupt_install_hook( preint_hook, NULL );
+  _MicroBlaze_Post_Interrupt_install_hook( postint_hook, NULL );
+  _User_extensions_Add_set( &mb_ext );
+
+  rtems_interrupt_lock_release( &target_lock, &lock_context );
+  return RTEMS_SUCCESSFUL;
+}
+
+int rtems_debugger_target_disable( void )
+{
+  debug_session_active = false;
+  rtems_interrupt_lock_context lock_context;
+
+  rtems_interrupt_lock_acquire( &target_lock, &lock_context );
+
+  _User_extensions_Remove_set( &mb_ext );
+
+  rtems_interrupt_lock_release( &target_lock, &lock_context );
+  return RTEMS_SUCCESSFUL;
+}
+
+int rtems_debugger_target_read_regs( rtems_debugger_thread *thread )
+{
+  if (
+    rtems_debugger_thread_flag(
+      thread,
+      RTEMS_DEBUGGER_THREAD_FLAG_REG_VALID
+    ) == 0
+  ) {
+    static const uintptr_t good_address = (uintptr_t) &good_address;
+    int                    i;
+
+    memset( &thread->registers[ 0 ], 0, RTEMS_DEBUGGER_NUMREGBYTES );
+
+    /* set all integer register to a known valid address */
+    for ( i = 0; i < RTEMS_DEBUGGER_NUMREGS; ++i ) {
+      rtems_debugger_set_int_reg( thread, i, (uintptr_t) &good_address );
+    }
+
+    if ( thread->frame != NULL ) {
+      CPU_Exception_frame *frame = thread->frame;
+
+      *( (CPU_Exception_frame *) thread->registers ) = *frame;
+      rtems_debugger_set_int_reg( thread, REG_R0, 0 );
+      rtems_debugger_set_int_reg( thread, REG_R1, frame->r1 );
+      rtems_debugger_set_int_reg( thread, REG_R2, frame->r2 );
+      rtems_debugger_set_int_reg( thread, REG_R3, frame->r3 );
+      rtems_debugger_set_int_reg( thread, REG_R4, frame->r4 );
+      rtems_debugger_set_int_reg( thread, REG_R5, frame->r5 );
+      rtems_debugger_set_int_reg( thread, REG_R6, frame->r6 );
+      rtems_debugger_set_int_reg( thread, REG_R7, frame->r7 );
+      rtems_debugger_set_int_reg( thread, REG_R8, frame->r8 );
+      rtems_debugger_set_int_reg( thread, REG_R9, frame->r9 );
+      rtems_debugger_set_int_reg( thread, REG_R10, frame->r10 );
+      rtems_debugger_set_int_reg( thread, REG_R11, frame->r11 );
+      rtems_debugger_set_int_reg( thread, REG_R12, frame->r12 );
+      rtems_debugger_set_int_reg( thread, REG_R13, frame->r13 );
+      rtems_debugger_set_int_reg( thread, REG_R14, (uintptr_t) frame->r14 );
+      rtems_debugger_set_int_reg( thread, REG_R15, (uintptr_t) frame->r15 );
+      rtems_debugger_set_int_reg( thread, REG_R16, (uintptr_t) frame->r16 );
+      rtems_debugger_set_int_reg( thread, REG_R17, (uintptr_t) frame->r17 );
+      rtems_debugger_set_int_reg( thread, REG_R18, frame->r18 );
+      rtems_debugger_set_int_reg( thread, REG_R19, frame->r19 );
+      rtems_debugger_set_int_reg( thread, REG_R20, frame->r20 );
+      rtems_debugger_set_int_reg( thread, REG_R21, frame->r21 );
+      rtems_debugger_set_int_reg( thread, REG_R22, frame->r22 );
+      rtems_debugger_set_int_reg( thread, REG_R23, frame->r23 );
+      rtems_debugger_set_int_reg( thread, REG_R24, frame->r24 );
+      rtems_debugger_set_int_reg( thread, REG_R25, frame->r25 );
+      rtems_debugger_set_int_reg( thread, REG_R26, frame->r26 );
+      rtems_debugger_set_int_reg( thread, REG_R27, frame->r27 );
+      rtems_debugger_set_int_reg( thread, REG_R28, frame->r28 );
+      rtems_debugger_set_int_reg( thread, REG_R29, frame->r29 );
+      rtems_debugger_set_int_reg( thread, REG_R30, frame->r30 );
+      rtems_debugger_set_int_reg( thread, REG_R31, frame->r31 );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_PC,
+        rtems_debugger_target_frame_pc( frame )
+      );
+      rtems_debugger_set_int_reg( thread, REG_MS, frame->msr );
+      rtems_debugger_set_int_reg( thread, REG_EA, (uintptr_t) frame->ear );
+      rtems_debugger_set_int_reg( thread, REG_ES, frame->esr );
+      rtems_debugger_set_int_reg( thread, REG_BT, (uintptr_t) frame->btr );
+      /*
+       * Get the signal from the frame.
+       */
+      thread->signal = rtems_debugger_target_exception_to_signal( frame );
+    } else {
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R1,
+        thread->tcb->Registers.r1
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R13,
+        thread->tcb->Registers.r13
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R14,
+        thread->tcb->Registers.r14
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R15,
+        thread->tcb->Registers.r15
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R16,
+        thread->tcb->Registers.r16
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R17,
+        thread->tcb->Registers.r17
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R18,
+        thread->tcb->Registers.r18
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R19,
+        thread->tcb->Registers.r19
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R20,
+        thread->tcb->Registers.r20
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R21,
+        thread->tcb->Registers.r21
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R22,
+        thread->tcb->Registers.r22
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R23,
+        thread->tcb->Registers.r23
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R24,
+        thread->tcb->Registers.r24
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R25,
+        thread->tcb->Registers.r25
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R26,
+        thread->tcb->Registers.r26
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R27,
+        thread->tcb->Registers.r27
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R28,
+        thread->tcb->Registers.r28
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R29,
+        thread->tcb->Registers.r29
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R30,
+        thread->tcb->Registers.r30
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_R31,
+        thread->tcb->Registers.r31
+      );
+      rtems_debugger_set_int_reg(
+        thread,
+        REG_MS,
+        (intptr_t) thread->tcb->Registers.rmsr
+      );
+      /*
+       * Blocked threads have no signal.
+       */
+      thread->signal = 0;
+    }
+
+    thread->flags |= RTEMS_DEBUGGER_THREAD_FLAG_REG_VALID;
+    thread->flags &= ~RTEMS_DEBUGGER_THREAD_FLAG_REG_DIRTY;
+  }
+
+  return 0;
+}
+
+int rtems_debugger_target_write_regs( rtems_debugger_thread *thread )
+{
+  if (
+    rtems_debugger_thread_flag(
+      thread,
+      RTEMS_DEBUGGER_THREAD_FLAG_REG_DIRTY
+    ) != 0
+  ) {
+    /*
+     * Only write to debugger controlled exception threads. Do not touch the
+     * registers for threads blocked in the context switcher.
+     */
+    if (
+      rtems_debugger_thread_flag(
+        thread,
+        RTEMS_DEBUGGER_THREAD_FLAG_EXCEPTION
+      ) != 0
+    ) {
+      CPU_Exception_frame *frame = thread->frame;
+      frame->r1 = rtems_debugger_get_int_reg( thread, REG_R1 );
+      frame->r2 = rtems_debugger_get_int_reg( thread, REG_R2 );
+      frame->r3 = rtems_debugger_get_int_reg( thread, REG_R3 );
+      frame->r4 = rtems_debugger_get_int_reg( thread, REG_R4 );
+      frame->r5 = rtems_debugger_get_int_reg( thread, REG_R5 );
+      frame->r6 = rtems_debugger_get_int_reg( thread, REG_R6 );
+      frame->r7 = rtems_debugger_get_int_reg( thread, REG_R7 );
+      frame->r8 = rtems_debugger_get_int_reg( thread, REG_R8 );
+      frame->r9 = rtems_debugger_get_int_reg( thread, REG_R9 );
+      frame->r10 = rtems_debugger_get_int_reg( thread, REG_R10 );
+      frame->r11 = rtems_debugger_get_int_reg( thread, REG_R11 );
+      frame->r12 = rtems_debugger_get_int_reg( thread, REG_R12 );
+      frame->r13 = rtems_debugger_get_int_reg( thread, REG_R13 );
+      frame->r14 = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_R14 );
+      frame->r15 = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_R15 );
+      frame->r16 = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_R16 );
+      frame->r17 = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_R17 );
+      frame->r18 = rtems_debugger_get_int_reg( thread, REG_R18 );
+      frame->r19 = rtems_debugger_get_int_reg( thread, REG_R19 );
+      frame->r20 = rtems_debugger_get_int_reg( thread, REG_R20 );
+      frame->r21 = rtems_debugger_get_int_reg( thread, REG_R21 );
+      frame->r22 = rtems_debugger_get_int_reg( thread, REG_R22 );
+      frame->r23 = rtems_debugger_get_int_reg( thread, REG_R23 );
+      frame->r24 = rtems_debugger_get_int_reg( thread, REG_R24 );
+      frame->r25 = rtems_debugger_get_int_reg( thread, REG_R25 );
+      frame->r26 = rtems_debugger_get_int_reg( thread, REG_R26 );
+      frame->r27 = rtems_debugger_get_int_reg( thread, REG_R27 );
+      frame->r28 = rtems_debugger_get_int_reg( thread, REG_R28 );
+      frame->r29 = rtems_debugger_get_int_reg( thread, REG_R29 );
+      frame->r30 = rtems_debugger_get_int_reg( thread, REG_R30 );
+      frame->r31 = rtems_debugger_get_int_reg( thread, REG_R31 );
+      frame->msr = rtems_debugger_get_int_reg( thread, REG_MS );
+      frame->ear = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_EA );
+      frame->esr = rtems_debugger_get_int_reg( thread, REG_ES );
+      frame->btr = (uint32_t *) rtems_debugger_get_int_reg( thread, REG_BT );
+    }
+
+    thread->flags &= ~RTEMS_DEBUGGER_THREAD_FLAG_REG_DIRTY;
+  }
+
+  return 0;
+}
+
+uintptr_t rtems_debugger_target_reg_pc( rtems_debugger_thread *thread )
+{
+  return thread->tcb->Registers.r15;
+}
+
+uintptr_t rtems_debugger_target_frame_pc( CPU_Exception_frame *frame )
+{
+  return (uintptr_t) _MicroBlaze_Get_return_address( frame );
+}
+
+uintptr_t rtems_debugger_target_reg_sp( rtems_debugger_thread *thread )
+{
+  int r;
+
+  r = rtems_debugger_target_read_regs( thread );
+
+  if ( r >= 0 ) {
+    return rtems_debugger_get_int_reg( thread, REG_R1 );
+  }
+
+  return 0;
+}
+
+uintptr_t rtems_debugger_target_tcb_sp( rtems_debugger_thread *thread )
+{
+  return (uintptr_t) thread->tcb->Registers.r1;
+}
+
+#define IGROUP_MASK 0x3f
+
+static uint32_t get_igroup( uint32_t ins )
+{
+  return ( ins >> 26 ) & IGROUP_MASK;
+}
+
+#define REGISTER_MASK 0x1f
+
+static uint32_t get_Ra( uint32_t ins )
+{
+  return ( ins >> 16 ) & REGISTER_MASK;
+}
+
+static uint32_t get_Rb( uint32_t ins )
+{
+  return ( ins >> 11 ) & REGISTER_MASK;
+}
+
+static uint32_t get_Rd( uint32_t ins )
+{
+  return ( ins >> 21 ) & REGISTER_MASK;
+}
+
+#define IMM16_MASK 0xffff
+
+static int32_t get_Imm16( uint32_t ins )
+{
+  int16_t base = (int16_t) ins & IMM16_MASK;
+
+  return base;
+}
+
+#define IMM24_MASK 0xffffff
+
+static int32_t get_Imm24( uint32_t ins )
+{
+  int32_t base = ins & IMM24_MASK;
+
+  /* Sign-extend manually if necessary */
+  if ( ( base & 0x800000 ) != 0 ) {
+    base &= 0xFF000000;
+  }
+
+  return base;
+}
+
+static int64_t get_Imm( uint32_t ins )
+{
+  if ( ( get_Rd( ins ) & 0x10 ) != 0 ) {
+    return get_Imm24( ins );
+  }
+
+  return get_Imm16( ins );
+}
+
+#define IMM_GROUP 0x2c
+
+static bool is_imm( uint32_t ins )
+{
+  return get_igroup( ins ) == IMM_GROUP;
+}
+
+#define RETURN_GROUP 0x2d
+
+static bool is_return( uint32_t ins )
+{
+  return get_igroup( ins ) == RETURN_GROUP;
+}
+
+/* Unconditional branch */
+#define UBRANCH_GROUP 0x26
+
+static bool is_ubranch( uint32_t ins )
+{
+  return get_igroup( ins ) == UBRANCH_GROUP;
+}
+
+/* Comparison branch */
+#define CBRANCH_GROUP 0x27
+
+static bool is_cbranch( uint32_t ins )
+{
+  return get_igroup( ins ) == CBRANCH_GROUP;
+}
+
+/* Unconditional Immediate branch */
+#define UIBRANCH_GROUP 0x2e
+
+static bool is_uibranch( uint32_t ins )
+{
+  /* Ra == 0x2 is a memory barrier which continues at the next instruction */
+  return get_igroup( ins ) == UIBRANCH_GROUP && get_Ra( ins ) != 0x2;
+}
+
+/* Comparison Immediate branch */
+#define CIBRANCH_GROUP 0x2f
+
+static bool is_cibranch( uint32_t ins )
+{
+  return get_igroup( ins ) == CIBRANCH_GROUP;
+}
+
+static bool branch_has_delay_slot( uint32_t ins )
+{
+  if ( is_ubranch( ins ) == true && ( get_Ra( ins ) & 0x10 ) != 0 ) {
+    return true;
+  }
+
+  if ( is_cbranch( ins ) == true && ( get_Ra( ins ) & 0x10 ) != 0 ) {
+    return true;
+  }
+
+  if ( is_uibranch( ins ) == true && ( get_Ra( ins ) & 0x10 ) != 0 ) {
+    return true;
+  }
+
+  if ( is_cibranch( ins ) == true && ( get_Rd( ins ) & 0x10 ) != 0 ) {
+    return true;
+  }
+
+  return false;
+}
+
+/* All return instructions have a delay slot */
+
+static bool branch_is_absolute( uint32_t ins )
+{
+  return ( is_ubranch( ins ) == true || is_uibranch( ins ) == true ) &&
+         ( get_Ra( ins ) & 0x8 ) != 0;
+}
+
+/* All returns are absolute */
+
+static bool target_is_absolute( uint32_t ins )
+{
+  return branch_is_absolute( ins ) == true || is_return( ins ) == true;
+}
+
+static bool is_branch( uint32_t ins )
+{
+  if ( is_ubranch( ins ) == true ) {
+    return true;
+  }
+
+  if ( is_cbranch( ins ) == true ) {
+    return true;
+  }
+
+  if ( is_uibranch( ins ) == true ) {
+    return true;
+  }
+
+  if ( is_cibranch( ins ) == true ) {
+    return true;
+  }
+
+  return false;
+}
+
+#define BRK_RA 0xC
+
+static bool is_brk( uint32_t ins )
+{
+  return ( is_ubranch( ins ) == true || is_uibranch( ins ) == true ) &&
+         get_Ra( ins ) == BRK_RA;
+}
+
+static uint32_t get_register_value(
+  CPU_Exception_frame *frame,
+  uint32_t             target_register
+)
+{
+  if ( target_register == 0 ) {
+    return 0;
+  }
+
+  /* Assumes all registers are contiguous and accounted for */
+  return ( &( frame->r1 ) )[ target_register - 1 ];
+}
+
+static void set_frame_pc( CPU_Exception_frame *frame, uint32_t *new_pc )
+{
+  Per_CPU_Control *cpu_self = _Per_CPU_Get();
+
+  /* Break in progress */
+  if ( ( frame->msr & MICROBLAZE_MSR_BIP ) != 0 ) {
+    frame->r16 = (uint32_t *) new_pc;
+    return;
+  }
+
+  /* Exception in progress */
+  if ( ( frame->msr & MICROBLAZE_MSR_EIP ) != 0 ) {
+    frame->r17 = (uint32_t *) new_pc;
+    return;
+  }
+
+  /* Interrupt in progress must be determined by stack pointer location */
+  if (
+    frame->r1 >= (uint32_t) cpu_self->interrupt_stack_low
+    && frame->r1 < (uint32_t) cpu_self->interrupt_stack_high
+  ) {
+    frame->r14 = (uint32_t *) new_pc;
+    return;
+  }
+
+  /* Default to normal link register */
+  frame->r15 = (uint32_t *) new_pc;
+}
+
+static uint32_t bypass_swbreaks( uint32_t *addr )
+{
+  rtems_debugger_target *target = rtems_debugger->target;
+
+  if ( target != NULL && target->swbreaks.block != NULL ) {
+    rtems_debugger_target_swbreak *swbreaks = target->swbreaks.block;
+    size_t                         i;
+
+    for ( i = 0; i < target->swbreaks.level; ++i ) {
+      if ( swbreaks[ i ].address == addr ) {
+        return *( (uint32_t *) &( swbreaks[ i ].contents[ 0 ] ) );
+      }
+    }
+  }
+
+  return *addr;
+}
+
+static bool addr_in_swbreaks( uint32_t *addr )
+{
+  size_t                         i;
+  rtems_debugger_target_swbreak *swbreaks;
+  rtems_debugger_target         *target = rtems_debugger->target;
+
+  if ( target == NULL ) {
+    return false;
+  }
+
+  swbreaks = target->swbreaks.block;
+
+  if ( swbreaks == NULL ) {
+    return false;
+  }
+
+  for ( i = 0; i < target->swbreaks.level; ++i ) {
+    if ( swbreaks[ i ].address == addr ) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+static int setup_single_step_breakpoints( CPU_Exception_frame *frame )
+{
+  /*
+   * It may be necessary to evaluate the current instruction and next immediate
+   * instruction to determine the address of the "next" instruction and possible
+   * branch target instructions
+   */
+  uint32_t *pc = (uint32_t *) rtems_debugger_target_frame_pc( frame );
+  int64_t   imm = 0;
+  uint32_t *resume_pc;
+
+  /*
+   * Normalize PC address to the real instruction and not any IMM. This deals
+   * with a possible cascade of IMM.
+   */
+  while ( is_imm( bypass_swbreaks( pc ) ) == true ) {
+    pc = &pc[ 1 ];
+  }
+
+  resume_pc = pc;
+
+  /*
+   * If execution ends up on a branch instruction that is preceeded by IMM, bad
+   * things can happen since it's not possible to know if the IMM was actually
+   * executed or something jumped to the branch directly. Exceptions treat IMM
+   * as part of the following instruction, so the RTEMS debugger will do so as
+   * well.
+   */
+  uint32_t bypass_ins = bypass_swbreaks( &pc[ -1 ] );
+
+  if ( is_imm( bypass_ins ) == true ) {
+    imm = get_Imm( bypass_ins );
+    imm <<= 16;
+    resume_pc = &pc[ -1 ];
+  }
+
+  uint32_t ins = bypass_swbreaks( pc );
+  bool     needs_target_break = false;
+  bool     needs_next_break = true;
+
+  if ( is_brk( ins ) == true ) {
+    /*
+     * If the instruction being stepped is brk or brki, something bad has
+     * happened. If this instruction is stepped, the target of the branch (the
+     * debug vector) has a brki placed in it which results in an tight infinite
+     * recursive call. Under normal circumstances, this shouldn't happen.
+     */
+    rtems_debugger_printf(
+      "rtems-db: Unable to set single-step breakpoints for brk/brki instructions\n"
+    );
+
+    return -1;
+  }
+
+  if ( is_branch( ins ) == true ) {
+    needs_target_break = true;
+
+    /*
+     * Unconditional branches (including returns) do not need to break on the
+     * next instruction.
+     */
+    if (
+      is_ubranch( ins ) == true
+      || is_uibranch( ins ) == true
+      || is_return( ins ) == true
+    ) {
+      needs_next_break = false;
+    }
+  }
+
+  if ( is_return( ins ) == true ) {
+    needs_target_break = true;
+    needs_next_break = false;
+  }
+
+  if ( needs_next_break == true ) {
+    uint32_t *next_ins = &pc[ 1 ];
+
+    if ( branch_has_delay_slot( ins ) == true ) {
+      next_ins = &pc[ 2 ];
+    }
+
+    if ( is_brk( *next_ins ) == false ) {
+      /* setup next instruction software break */
+      set_soft_break( &next_soft_break, next_ins );
+    }
+  }
+
+  if ( imm != 0 ) {
+    imm |= ( get_Imm16( ins ) & 0xFFFF );
+  } else {
+    imm = get_Imm16( ins );
+  }
+
+  if ( needs_target_break == true ) {
+    /* Calculate target address */
+    uintptr_t target_ins = 0;
+
+    if ( target_is_absolute( ins ) == false ) {
+      target_ins += (uintptr_t) pc;
+    }
+
+    if (
+      is_uibranch( ins ) == true || is_cibranch( ins ) == true ||
+      is_return( ins ) == true
+    ) {
+      target_ins += imm;
+    }
+
+    if ( is_return( ins ) == true ) {
+      uint32_t target_register = get_Ra( ins );
+      target_ins += get_register_value( frame, target_register );
+    }
+
+    if ( is_ubranch( ins ) == true || is_cbranch( ins ) == true ) {
+      uint32_t target_register = get_Rb( ins );
+      target_ins += get_register_value( frame, target_register );
+    }
+
+    if ( is_brk( *( (uint32_t *) target_ins ) ) == false ) {
+      /* setup target instruction software break */
+      set_soft_break( &target_soft_break, (uint32_t *) target_ins );
+    }
+  }
+
+  /* Alter resume address */
+  set_frame_pc( frame, resume_pc );
+
+  return 0;
+}
+
+int rtems_debugger_target_thread_stepping( rtems_debugger_thread *thread )
+{
+  CPU_Exception_frame *frame = thread->frame;
+  int                  ret = 0;
+
+  if (
+    rtems_debugger_thread_flag(
+      thread,
+      RTEMS_DEBUGGER_THREAD_FLAG_STEP_INSTR
+    ) != 0
+  ) {
+    /* Especially on first startup, frame isn't guaranteed to be non-NULL */
+    if ( frame == NULL ) {
+      return -1;
+    }
+
+    /* set software breakpoint(s) here */
+    ret = setup_single_step_breakpoints( frame );
+  }
+
+  return ret;
+}
+
+int rtems_debugger_target_exception_to_signal( CPU_Exception_frame *frame )
+{
+  uint32_t BiP = frame->msr & MICROBLAZE_MSR_BIP;
+  uint32_t EiP = frame->msr & MICROBLAZE_MSR_EIP;
+
+  if ( BiP != 0 ) {
+    return RTEMS_DEBUGGER_SIGNAL_TRAP;
+  }
+
+  if ( EiP != 0 ) {
+    uint32_t EC = frame->esr & 0x1f;
+
+    switch ( EC ) {
+     case 0x0: /* FSL */
+     case 0x1: /* Unaligned data access */
+     case 0x3: /* instruction fetch */
+     case 0x4: /* data bus error */
+     case 0x10: /* MMU data storage */
+     case 0x11: /* MMU instruction storage */
+     case 0x12: /* MMU data TLB miss */
+     case 0x13: /* MMU instruction TLB miss */
+       return RTEMS_DEBUGGER_SIGNAL_SEGV;
+
+     case 0x7: /* priveleged */
+       return RTEMS_DEBUGGER_SIGNAL_TRAP;
+
+     case 0x5: /* div/0 */
+     case 0x6: /* FPU */
+       return RTEMS_DEBUGGER_SIGNAL_FPE;
+
+     case 0x2: /* illegal opcode (unknown instruction) */
+
+       /* Check for the illegal opcode being used in place of brki */
+       if ( addr_in_swbreaks( frame->r17 ) ) {
+         return RTEMS_DEBUGGER_SIGNAL_TRAP;
+       }
+
+     default:
+       return RTEMS_DEBUGGER_SIGNAL_ILL;
+    }
+  }
+
+  /* Default to SIGILL */
+  return RTEMS_DEBUGGER_SIGNAL_ILL;
+}
+
+void rtems_debugger_target_exception_print( CPU_Exception_frame *frame )
+{
+  EXC_FRAME_PRINT( rtems_debugger_printf, "", frame );
+}
+
+/*
+ * Debug hardware is inaccessible to the CPU, so hardware breaks and watchpoints
+ * are not supported.
+ */
+int rtems_debugger_target_hwbreak_insert( void )
+{
+  return 0;
+}
+
+int rtems_debugger_target_hwbreak_remove( void )
+{
+  return 0;
+}
+
+int rtems_debugger_target_hwbreak_control(
+  rtems_debugger_target_watchpoint wp,
+  bool                             insert,
+  uintptr_t                        addr,
+  DB_UINT                          kind
+)
+{
+  return 0;
+}
+
+int rtems_debugger_target_cache_sync( rtems_debugger_target_swbreak *swbreak )
+{
+  /*
+   * Flush the data cache and invalidate the instruction cache.
+   */
+  rtems_cache_flush_multiple_data_lines(
+    swbreak->address,
+    sizeof( breakpoint )
+  );
+  rtems_cache_instruction_sync_after_code_change(
+    swbreak->address,
+    sizeof( breakpoint )
+  );
+  return 0;
+}
diff --git a/cpukit/score/cpu/microblaze/include/rtems/score/cpu.h b/cpukit/score/cpu/microblaze/include/rtems/score/cpu.h
index 253810ad59..35874dc1c4 100644
--- a/cpukit/score/cpu/microblaze/include/rtems/score/cpu.h
+++ b/cpukit/score/cpu/microblaze/include/rtems/score/cpu.h
@@ -208,6 +208,30 @@ typedef struct {
 #define _CPU_MSR_SET( _msr_value ) \
 { __asm__ volatile ("mts rmsr, %0" : "=&r" ((_msr_value)) : "0" ((_msr_value))); }
 
+#define MICROBLAZE_PVR0_VERSION_GET( _pvr0_value ) \
+  ( ( _pvr0_value >> 8 ) & 0xff )
+
+#define _CPU_PVR0_GET( _pvr0_value ) \
+  do { \
+    ( _pvr0_value ) = 0; \
+    __asm__ volatile ( "mfs %0, rpvr0" : "=&r" ( ( _pvr0_value ) ) ); \
+  } while ( 0 )
+
+#define MICROBLAZE_PVR3_BP_GET( _pvr3_value ) \
+  ( ( _pvr3_value >> 25 ) & 0xf )
+
+#define MICROBLAZE_PVR3_RWP_GET( _pvr3_value ) \
+  ( ( _pvr3_value >> 19 ) & 0x7 )
+
+#define MICROBLAZE_PVR3_WWP_GET( _pvr3_value ) \
+  ( ( _pvr3_value >> 13 ) & 0x7 )
+
+#define _CPU_PVR3_GET( _pvr3_value ) \
+  do { \
+    ( _pvr3_value ) = 0; \
+    __asm__ volatile ( "mfs %0, rpvr3" : "=&r" ( ( _pvr3_value ) ) ); \
+  } while ( 0 )
+
 #define _CPU_ISR_Disable( _isr_cookie ) \
   { \
     unsigned int _new_msr;  \
diff --git a/spec/build/cpukit/libdebugger.yml b/spec/build/cpukit/libdebugger.yml
index 9b50adbe77..263a4994f0 100644
--- a/spec/build/cpukit/libdebugger.yml
+++ b/spec/build/cpukit/libdebugger.yml
@@ -16,6 +16,8 @@ links:
   uid: objdbgarm
 - role: build-dependency
   uid: objdbgi386
+- role: build-dependency
+  uid: objdbgmicroblaze
 source:
 - cpukit/libdebugger/rtems-debugger-block.c
 - cpukit/libdebugger/rtems-debugger-bsp.c
diff --git a/spec/build/cpukit/objdbgmicroblaze.yml b/spec/build/cpukit/objdbgmicroblaze.yml
new file mode 100644
index 0000000000..59219ae507
--- /dev/null
+++ b/spec/build/cpukit/objdbgmicroblaze.yml
@@ -0,0 +1,15 @@
+SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
+build-type: objects
+cflags: []
+copyrights:
+- Copyright (C) 2022 On-Line Applications Research (OAR)
+cppflags: []
+cxxflags: []
+enabled-by:
+- microblaze
+includes: []
+install: []
+links: []
+source:
+- cpukit/libdebugger/rtems-debugger-microblaze.c
+type: build
diff --git a/spec/build/cpukit/optlibdebugger.yml b/spec/build/cpukit/optlibdebugger.yml
index a89a495528..c657db4ba4 100644
--- a/spec/build/cpukit/optlibdebugger.yml
+++ b/spec/build/cpukit/optlibdebugger.yml
@@ -12,6 +12,7 @@ enabled-by:
 - aarch64
 - arm
 - i386
+- microblaze
 links: []
 name: BUILD_LIBDEBUGGER
 type: build
-- 
2.30.2



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