MIPS: Implement gem5/src/arch/mips/remote_gdb.cc.

So a mips-cross-gdb can connect with gem5(MIPS_SE), and do some remote
debugging.

Testing:

Build gem5 for MIPS_SE and make gem5 wait at beginning:
modify "rgdb_wait = -1" to "rgdb_wait = 0" in src/sim/system.cc;
scons build/MIPS_SE/gem5.opt CPU_MODELS=O3CPU
----
Build GDB-7.3 mips-cross:
./configure --target=mips-linux-gnu --prefix=xxx/gdb-7.3-install/
make
make install
----
Run:
./build/MIPS_SE/gem5.opt configs/example/se.py --detailed --caches
./mips-linux-gnu-gdb xxx/gem5/tests/test-progs/hello/bin/mips/linux/hello
(gdb) target remote :7000
(gdb) info registers
(gdb) disassemble
(gdb) si
(gdb) break main
(gdb) c
(gdb) quit
Testing done.

3 files changed, 346 insertions, 17 deletions

diff --git a/src/arch/mips/SConscript b/src/arch/mips/SConscript
index 46c0dd914..9fc2b71ff 100644
--- a/src/arch/mips/SConscript
+++ b/src/arch/mips/SConscript
@@ -39,6 +39,7 @@ if env['TARGET_ISA'] == 'mips':
     Source('pagetable.cc')
     Source('utility.cc')
     Source('dsp.cc')
+    Source('remote_gdb.cc')
 
     SimObject('MipsTLB.py')
     DebugFlag('MipsPRA')
diff --git a/src/arch/mips/remote_gdb.cc b/src/arch/mips/remote_gdb.cc
new file mode 100644
index 000000000..1fd157758
--- /dev/null
+++ b/src/arch/mips/remote_gdb.cc
@@ -0,0 +1,299 @@
+/*
+ * Copyright (c) 2010 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Copyright (c) 2002-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * 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;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * 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.
+ *
+ * Authors: Nathan Binkert
+ *          William Wang
+ *          Deyuan Guo
+ */
+
+/*
+ * Copyright (c) 1990, 1993 The Regents of the University of California
+ * All rights reserved
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ *      This product includes software developed by the University of
+ *      California, Lawrence Berkeley Laboratories.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by the University of
+ *      California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ *      @(#)kgdb_stub.c 8.4 (Berkeley) 1/12/94
+ */
+
+/*-
+ * Copyright (c) 2001 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by the NetBSD
+ *      Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+/*
+ * $NetBSD: kgdb_stub.c,v 1.8 2001/07/07 22:58:00 wdk Exp $
+ *
+ * Taken from NetBSD
+ *
+ * "Stub" to allow remote cpu to debug over a serial line using gdb.
+ */
+
+#include <sys/signal.h>
+#include <unistd.h>
+
+#include <string>
+
+#include "arch/mips/remote_gdb.hh"
+#include "arch/mips/vtophys.hh"
+#include "config/full_system.hh"
+#include "cpu/decode.hh"
+#include "cpu/thread_state.hh"
+#include "debug/GDBAcc.hh"
+#include "debug/GDBMisc.hh"
+#include "mem/page_table.hh"
+
+using namespace std;
+using namespace MipsISA;
+
+RemoteGDB::RemoteGDB(System *_system, ThreadContext *tc)
+    : BaseRemoteGDB(_system, tc, GdbNumRegs)
+{
+}
+
+/*
+ * Determine if the mapping at va..(va+len) is valid.
+ */
+bool
+RemoteGDB::acc(Addr va, size_t len)
+{
+#if FULL_SYSTEM
+    panic("acc not implemented for MIPS FS!");
+#endif
+    TlbEntry entry;
+    //Check to make sure the first byte is mapped into the processes address
+    //space.
+    return context->getProcessPtr()->pTable->lookup(va, entry);
+}
+
+/*
+ * Translate the kernel debugger register format into the GDB register
+ * format.
+ */
+void
+RemoteGDB::getregs()
+{
+    DPRINTF(GDBAcc, "getregs in remotegdb \n");
+    memset(gdbregs.regs, 0, gdbregs.bytes());
+
+    // MIPS registers are 32 bits wide, gdb registers are 64 bits wide
+    // two MIPS registers are packed into one gdb register (little endian)
+
+    // INTREG: R0~R31
+    for (int i = 0; i < GdbIntArchRegs; i++) {
+        gdbregs.regs[i] = pack(
+                context->readIntReg(i * 2),
+                context->readIntReg(i * 2 + 1));
+    }
+    // SR, LO, HI, BADVADDR, CAUSE, PC
+    gdbregs.regs[GdbIntArchRegs + 0] = pack(
+                context->readMiscRegNoEffect(MISCREG_STATUS),
+                context->readIntReg(INTREG_LO));
+    gdbregs.regs[GdbIntArchRegs + 1] = pack(
+                context->readIntReg(INTREG_HI),
+                context->readMiscRegNoEffect(MISCREG_BADVADDR));
+    gdbregs.regs[GdbIntArchRegs + 2] = pack(
+                context->readMiscRegNoEffect(MISCREG_CAUSE),
+                context->pcState().pc());
+    // FLOATREG: F0~F31
+    for (int i = 0; i < GdbFloatArchRegs; i++) {
+        gdbregs.regs[GdbIntRegs + i] = pack(
+                context->readFloatRegBits(i * 2),
+                context->readFloatRegBits(i * 2 + 1));
+    }
+    // FCR, FIR
+    gdbregs.regs[GdbIntRegs + GdbFloatArchRegs + 0] = pack(
+                context->readFloatRegBits(FLOATREG_FCCR),
+                context->readFloatRegBits(FLOATREG_FIR));
+}
+
+/*
+ * Translate the GDB register format into the kernel debugger register
+ * format.
+ */
+void
+RemoteGDB::setregs()
+{
+    DPRINTF(GDBAcc, "setregs in remotegdb \n");
+
+    // MIPS registers are 32 bits wide, gdb registers are 64 bits wide
+    // two MIPS registers are packed into one gdb register (little endian)
+
+    // INTREG: R0~R31
+    for (int i = 0; i < GdbIntArchRegs; i++) {
+        if (i) context->setIntReg(i * 2,
+                unpackLo(gdbregs.regs[i]));
+        context->setIntReg(i * 2 + 1,
+                unpackHi(gdbregs.regs[i]));
+    }
+    // SR, LO, HI, BADVADDR, CAUSE, PC
+    context->setMiscRegNoEffect(MISCREG_STATUS,
+                unpackLo(gdbregs.regs[GdbIntArchRegs + 0]));
+    context->setIntReg(INTREG_LO,
+                unpackHi(gdbregs.regs[GdbIntArchRegs + 0]));
+    context->setIntReg(INTREG_HI,
+                unpackLo(gdbregs.regs[GdbIntArchRegs + 1]));
+    context->setMiscRegNoEffect(MISCREG_BADVADDR,
+                unpackHi(gdbregs.regs[GdbIntArchRegs + 1]));
+    context->setMiscRegNoEffect(MISCREG_CAUSE,
+                unpackLo(gdbregs.regs[GdbIntArchRegs + 2]));
+    context->pcState(
+                unpackHi(gdbregs.regs[GdbIntArchRegs + 2]));
+    // FLOATREG: F0~F31
+    for (int i = 0; i < GdbFloatArchRegs; i++) {
+        context->setFloatRegBits(i * 2,
+                unpackLo(gdbregs.regs[GdbIntRegs + i]));
+        context->setFloatRegBits(i * 2 + 1,
+                unpackHi(gdbregs.regs[GdbIntRegs + i]));
+    }
+    // FCR, FIR
+    context->setFloatRegBits(FLOATREG_FCCR,
+                unpackLo(gdbregs.regs[GdbIntRegs + GdbFloatArchRegs + 0]));
+    context->setFloatRegBits(FLOATREG_FIR,
+                unpackHi(gdbregs.regs[GdbIntRegs + GdbFloatArchRegs + 0]));
+}
+
+void
+RemoteGDB::clearSingleStep()
+{
+    DPRINTF(GDBMisc, "clearSingleStep bt_addr=%#x nt_addr=%#x\n",
+            takenBkpt, notTakenBkpt);
+
+    if (takenBkpt != 0)
+        clearTempBreakpoint(takenBkpt);
+
+    if (notTakenBkpt != 0)
+        clearTempBreakpoint(notTakenBkpt);
+}
+
+void
+RemoteGDB::setSingleStep()
+{
+    PCState pc = context->pcState();
+    PCState bpc;
+    bool set_bt = false;
+
+    // User was stopped at pc, e.g. the instruction at pc was not
+    // executed.
+    MachInst inst = read<MachInst>(pc.pc());
+    StaticInstPtr si = context->getDecoderPtr()->decode(inst, pc.pc());
+    if (si->hasBranchTarget(pc, context, bpc)) {
+        // Don't bother setting a breakpoint on the taken branch if it
+        // is the same as the next npc
+        if (bpc.npc() != pc.nnpc())
+            set_bt = true;
+    }
+
+    DPRINTF(GDBMisc, "setSingleStep bt_addr=%#x nt_addr=%#x\n",
+            takenBkpt, notTakenBkpt);
+
+    notTakenBkpt = pc.nnpc();
+    setTempBreakpoint(notTakenBkpt);
+
+    if (set_bt) {
+        takenBkpt = bpc.npc();
+        setTempBreakpoint(takenBkpt);
+    }
+}
+
diff --git a/src/arch/mips/remote_gdb.hh b/src/arch/mips/remote_gdb.hh
index 03486a596..18215ff8f 100644
--- a/src/arch/mips/remote_gdb.hh
+++ b/src/arch/mips/remote_gdb.hh
@@ -31,34 +31,63 @@
 #ifndef __ARCH_MIPS_REMOTE_GDB_HH__
 #define __ARCH_MIPS_REMOTE_GDB_HH__
 
+#include "arch/mips/registers.hh"
+#include "base/bitfield.hh"
 #include "base/remote_gdb.hh"
 
+class System;
+class ThreadContext;
+class PhysicalMemory;
+
 namespace MipsISA
 {
+
+    // The number of special regs depends on gdb.
+    // Two 32-bit regs are packed into one 64-bit reg.
+    const int GdbIntArchRegs = NumIntArchRegs / 2;
+    const int GdbIntSpecialRegs = 6 / 2;
+    const int GdbFloatArchRegs = NumFloatArchRegs / 2;
+    const int GdbFloatSpecialRegs = 2 / 2;
+
+    const int GdbIntRegs = GdbIntArchRegs + GdbIntSpecialRegs;
+    const int GdbFloatRegs = GdbFloatArchRegs + GdbFloatSpecialRegs;
+    const int GdbNumRegs = GdbIntRegs + GdbFloatRegs;
+
     class RemoteGDB : public BaseRemoteGDB
     {
-      public:
-        //These needs to be written to suit MIPS
-
-        RemoteGDB(System *system, ThreadContext *context)
-            : BaseRemoteGDB(system, context, 1)
-        {}
+      protected:
+        Addr notTakenBkpt;
+        Addr takenBkpt;
 
-        bool acc(Addr, size_t)
-        { panic("acc not implemented for MIPS!"); }
+      public:
+        RemoteGDB(System *_system, ThreadContext *tc);
 
-        void getregs()
-        { panic("getregs not implemented for MIPS!"); }
+      protected:
+        bool acc(Addr addr, size_t len);
 
-        void setregs()
-        { panic("setregs not implemented for MIPS!"); }
+        void getregs();
+        void setregs();
 
-        void clearSingleStep()
-        { panic("clearSingleStep not implemented for MIPS!"); }
+        void clearSingleStep();
+        void setSingleStep();
 
-        void setSingleStep()
-        { panic("setSingleStep not implemented for MIPS!"); }
+      private:
+        uint64_t
+        pack(uint32_t lo, uint32_t hi)
+        {
+            return static_cast<uint64_t>(hi) << 32 | lo;
+        }
+        uint32_t
+        unpackLo(uint64_t val)
+        {
+            return bits(val, 31, 0);
+        }
+        uint32_t
+        unpackHi(uint64_t val)
+        {
+            return bits(val, 63, 32);
+        }
     };
 }
 
-#endif /* __ARCH_ALPHA_REMOTE_GDB_H__ */
+#endif /* __ARCH_MIPS_REMOTE_GDB_H__ */