x86: Implement a remote GDB stub.

This stub should allow remote debugging of 32 bit and 64 bit targets. Single
stepping seems to work, as do breakpoints. If both breakpoints and single
stepping affect an instruction, gdb will stop at the instruction twice before
continuing. That's a little surprising, but is generally harmless.

2 files changed, 263 insertions, 27 deletions

diff --git a/src/arch/x86/remote_gdb.cc b/src/arch/x86/remote_gdb.cc
index c7bce59bf..b30bf5739 100644
--- a/src/arch/x86/remote_gdb.cc
+++ b/src/arch/x86/remote_gdb.cc
@@ -1,4 +1,5 @@
 /*
+ * Copyright 2014 Google, Inc.
  * Copyright (c) 2007 The Hewlett-Packard Development Company
  * All rights reserved.
  *
@@ -42,41 +43,204 @@
 
 #include <string>
 
+#include "arch/x86/regs/int.hh"
+#include "arch/x86/regs/misc.hh"
+#include "arch/x86/pagetable_walker.hh"
+#include "arch/x86/process.hh"
 #include "arch/x86/remote_gdb.hh"
 #include "arch/vtophys.hh"
 #include "base/remote_gdb.hh"
 #include "base/socket.hh"
 #include "base/trace.hh"
+#include "cpu/base.hh"
 #include "cpu/thread_context.hh"
+#include "mem/page_table.hh"
+#include "sim/full_system.hh"
 
 using namespace std;
 using namespace X86ISA;
 
-RemoteGDB::RemoteGDB(System *_system, ThreadContext *c)
-    : BaseRemoteGDB(_system, c, NumGDBRegs)
+RemoteGDB::RemoteGDB(System *_system, ThreadContext *c) :
+    BaseRemoteGDB(_system, c, GDB_REG_BYTES), singleStepEvent(this)
 {}
 
-bool RemoteGDB::acc(Addr va, size_t len)
+bool
+RemoteGDB::acc(Addr va, size_t len)
 {
-    panic("Remote gdb acc not implemented in x86!\n");
+    if (FullSystem) {
+        Walker *walker = context->getDTBPtr()->getWalker();
+        unsigned logBytes;
+        Fault fault = walker->startFunctional(context, va, logBytes,
+                                              BaseTLB::Read);
+        if (fault != NoFault)
+            return false;
+
+        Addr endVa = va + len - 1;
+        if ((va & ~mask(logBytes)) == (endVa & ~mask(logBytes)))
+            return true;
+
+        fault = walker->startFunctional(context, endVa, logBytes,
+                                        BaseTLB::Read);
+        return fault == NoFault;
+    } else {
+        TlbEntry entry;
+        return context->getProcessPtr()->pTable->lookup(va, entry);
+    }
+}
+
+void
+RemoteGDB::SingleStepEvent::process()
+{
+    if (!gdb->singleStepEvent.scheduled())
+        gdb->scheduleInstCommitEvent(&gdb->singleStepEvent, 1);
+    gdb->trap(SIGTRAP);
 }
 
-void RemoteGDB::getregs()
+void
+RemoteGDB::getregs()
 {
-    panic("Remote gdb getregs not implemented in x86!\n");
+    HandyM5Reg m5reg = context->readMiscRegNoEffect(MISCREG_M5_REG);
+    if (m5reg.submode == SixtyFourBitMode) {
+        gdbregs.regs64[GDB64_RAX] = context->readIntReg(INTREG_RAX);
+        gdbregs.regs64[GDB64_RBX] = context->readIntReg(INTREG_RBX);
+        gdbregs.regs64[GDB64_RCX] = context->readIntReg(INTREG_RCX);
+        gdbregs.regs64[GDB64_RDX] = context->readIntReg(INTREG_RDX);
+        gdbregs.regs64[GDB64_RSI] = context->readIntReg(INTREG_RSI);
+        gdbregs.regs64[GDB64_RDI] = context->readIntReg(INTREG_RDI);
+        gdbregs.regs64[GDB64_RBP] = context->readIntReg(INTREG_RBP);
+        gdbregs.regs64[GDB64_RSP] = context->readIntReg(INTREG_RSP);
+        gdbregs.regs64[GDB64_R8] = context->readIntReg(INTREG_R8);
+        gdbregs.regs64[GDB64_R9] = context->readIntReg(INTREG_R9);
+        gdbregs.regs64[GDB64_R10] = context->readIntReg(INTREG_R10);
+        gdbregs.regs64[GDB64_R11] = context->readIntReg(INTREG_R11);
+        gdbregs.regs64[GDB64_R12] = context->readIntReg(INTREG_R12);
+        gdbregs.regs64[GDB64_R13] = context->readIntReg(INTREG_R13);
+        gdbregs.regs64[GDB64_R14] = context->readIntReg(INTREG_R14);
+        gdbregs.regs64[GDB64_R15] = context->readIntReg(INTREG_R15);
+        gdbregs.regs64[GDB64_RIP] = context->pcState().pc();
+        gdbregs.regs32[GDB64_RFLAGS_32] =
+            context->readMiscRegNoEffect(MISCREG_RFLAGS);
+        gdbregs.regs32[GDB64_CS_32] = context->readMiscRegNoEffect(MISCREG_CS);
+        gdbregs.regs32[GDB64_SS_32] = context->readMiscRegNoEffect(MISCREG_SS);
+        gdbregs.regs32[GDB64_DS_32] = context->readMiscRegNoEffect(MISCREG_DS);
+        gdbregs.regs32[GDB64_ES_32] = context->readMiscRegNoEffect(MISCREG_ES);
+        gdbregs.regs32[GDB64_FS_32] = context->readMiscRegNoEffect(MISCREG_FS);
+        gdbregs.regs32[GDB64_GS_32] = context->readMiscRegNoEffect(MISCREG_GS);
+    } else {
+        gdbregs.regs32[GDB32_EAX] = context->readIntReg(INTREG_RAX);
+        gdbregs.regs32[GDB32_ECX] = context->readIntReg(INTREG_RCX);
+        gdbregs.regs32[GDB32_EDX] = context->readIntReg(INTREG_RDX);
+        gdbregs.regs32[GDB32_EBX] = context->readIntReg(INTREG_RBX);
+        gdbregs.regs32[GDB32_ESP] = context->readIntReg(INTREG_RSP);
+        gdbregs.regs32[GDB32_EBP] = context->readIntReg(INTREG_RBP);
+        gdbregs.regs32[GDB32_ESI] = context->readIntReg(INTREG_RSI);
+        gdbregs.regs32[GDB32_EDI] = context->readIntReg(INTREG_RDI);
+        gdbregs.regs32[GDB32_EIP] = context->pcState().pc();
+        gdbregs.regs32[GDB32_EFLAGS] =
+            context->readMiscRegNoEffect(MISCREG_RFLAGS);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_CS);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_SS);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_DS);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_ES);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_FS);
+        gdbregs.regs32[GDB32_CS] = context->readMiscRegNoEffect(MISCREG_GS);
+    }
 }
 
-void RemoteGDB::setregs()
+void
+RemoteGDB::setregs()
 {
-    panic("Remote gdb setregs not implemented in x86!\n");
+    HandyM5Reg m5reg = context->readMiscRegNoEffect(MISCREG_M5_REG);
+    if (m5reg.submode == SixtyFourBitMode) {
+        context->setIntReg(INTREG_RAX, gdbregs.regs64[GDB64_RAX]);
+        context->setIntReg(INTREG_RBX, gdbregs.regs64[GDB64_RBX]);
+        context->setIntReg(INTREG_RCX, gdbregs.regs64[GDB64_RCX]);
+        context->setIntReg(INTREG_RDX, gdbregs.regs64[GDB64_RDX]);
+        context->setIntReg(INTREG_RSI, gdbregs.regs64[GDB64_RSI]);
+        context->setIntReg(INTREG_RDI, gdbregs.regs64[GDB64_RDI]);
+        context->setIntReg(INTREG_RBP, gdbregs.regs64[GDB64_RBP]);
+        context->setIntReg(INTREG_RSP, gdbregs.regs64[GDB64_RSP]);
+        context->setIntReg(INTREG_R8, gdbregs.regs64[GDB64_R8]);
+        context->setIntReg(INTREG_R9, gdbregs.regs64[GDB64_R9]);
+        context->setIntReg(INTREG_R10, gdbregs.regs64[GDB64_R10]);
+        context->setIntReg(INTREG_R11, gdbregs.regs64[GDB64_R11]);
+        context->setIntReg(INTREG_R12, gdbregs.regs64[GDB64_R12]);
+        context->setIntReg(INTREG_R13, gdbregs.regs64[GDB64_R13]);
+        context->setIntReg(INTREG_R14, gdbregs.regs64[GDB64_R14]);
+        context->setIntReg(INTREG_R15, gdbregs.regs64[GDB64_R15]);
+        context->pcState(gdbregs.regs64[GDB64_RIP]);
+        context->setMiscReg(MISCREG_RFLAGS, gdbregs.regs32[GDB64_RFLAGS_32]);
+        if (gdbregs.regs32[GDB64_CS_32] !=
+            context->readMiscRegNoEffect(MISCREG_CS)) {
+            warn("Remote gdb: Ignoring update to CS.\n");
+        }
+        if (gdbregs.regs32[GDB64_SS_32] !=
+            context->readMiscRegNoEffect(MISCREG_SS)) {
+            warn("Remote gdb: Ignoring update to SS.\n");
+        }
+        if (gdbregs.regs32[GDB64_DS_32] !=
+            context->readMiscRegNoEffect(MISCREG_DS)) {
+            warn("Remote gdb: Ignoring update to DS.\n");
+        }
+        if (gdbregs.regs32[GDB64_ES_32] !=
+            context->readMiscRegNoEffect(MISCREG_ES)) {
+            warn("Remote gdb: Ignoring update to ES.\n");
+        }
+        if (gdbregs.regs32[GDB64_FS_32] !=
+            context->readMiscRegNoEffect(MISCREG_FS)) {
+            warn("Remote gdb: Ignoring update to FS.\n");
+        }
+        if (gdbregs.regs32[GDB64_GS_32] !=
+            context->readMiscRegNoEffect(MISCREG_GS)) {
+            warn("Remote gdb: Ignoring update to GS.\n");
+        }
+    } else {
+        context->setIntReg(INTREG_RAX, gdbregs.regs32[GDB32_EAX]);
+        context->setIntReg(INTREG_RCX, gdbregs.regs32[GDB32_ECX]);
+        context->setIntReg(INTREG_RDX, gdbregs.regs32[GDB32_EDX]);
+        context->setIntReg(INTREG_RBX, gdbregs.regs32[GDB32_EBX]);
+        context->setIntReg(INTREG_RSP, gdbregs.regs32[GDB32_ESP]);
+        context->setIntReg(INTREG_RBP, gdbregs.regs32[GDB32_EBP]);
+        context->setIntReg(INTREG_RSI, gdbregs.regs32[GDB32_ESI]);
+        context->setIntReg(INTREG_RDI, gdbregs.regs32[GDB32_EDI]);
+        context->pcState(gdbregs.regs32[GDB32_EIP]);
+        context->setMiscReg(MISCREG_RFLAGS, gdbregs.regs32[GDB32_EFLAGS]);
+        if (gdbregs.regs32[GDB64_CS_32] !=
+            context->readMiscRegNoEffect(MISCREG_CS)) {
+            warn("Remote gdb: Ignoring update to CS.\n");
+        }
+        if (gdbregs.regs32[GDB32_SS] !=
+            context->readMiscRegNoEffect(MISCREG_SS)) {
+            warn("Remote gdb: Ignoring update to SS.\n");
+        }
+        if (gdbregs.regs32[GDB32_DS] !=
+            context->readMiscRegNoEffect(MISCREG_DS)) {
+            warn("Remote gdb: Ignoring update to DS.\n");
+        }
+        if (gdbregs.regs32[GDB32_ES] !=
+            context->readMiscRegNoEffect(MISCREG_ES)) {
+            warn("Remote gdb: Ignoring update to ES.\n");
+        }
+        if (gdbregs.regs32[GDB32_FS] !=
+            context->readMiscRegNoEffect(MISCREG_FS)) {
+            warn("Remote gdb: Ignoring update to FS.\n");
+        }
+        if (gdbregs.regs32[GDB32_GS] !=
+            context->readMiscRegNoEffect(MISCREG_GS)) {
+            warn("Remote gdb: Ignoring update to GS.\n");
+        }
+    }
 }
 
-void RemoteGDB::clearSingleStep()
+void
+RemoteGDB::clearSingleStep()
 {
-    panic("Remote gdb clearSingleStep not implemented in x86!\n");
+    descheduleInstCommitEvent(&singleStepEvent);
 }
 
-void RemoteGDB::setSingleStep()
+void
+RemoteGDB::setSingleStep()
 {
-    panic("Remoge gdb setSingleStep not implemented in x86!\n");
+    if (!singleStepEvent.scheduled())
+        scheduleInstCommitEvent(&singleStepEvent, 1);
 }
diff --git a/src/arch/x86/remote_gdb.hh b/src/arch/x86/remote_gdb.hh
index f8b15a818..b654fc2f8 100644
--- a/src/arch/x86/remote_gdb.hh
+++ b/src/arch/x86/remote_gdb.hh
@@ -1,4 +1,5 @@
 /*
+ * Copyright 2014 Google, Inc.
  * Copyright (c) 2007 The Hewlett-Packard Development Company
  * All rights reserved.
  *
@@ -40,6 +41,8 @@
 #ifndef __ARCH_X86_REMOTEGDB_HH__
 #define __ARCH_X86_REMOTEGDB_HH__
 
+#include <algorithm>
+
 #include "arch/x86/types.hh"
 #include "base/remote_gdb.hh"
 
@@ -48,29 +51,98 @@ class ThreadContext;
 
 namespace X86ISA
 {
-    class RemoteGDB : public BaseRemoteGDB
+class RemoteGDB : public BaseRemoteGDB
+{
+  public:
+    enum
     {
-      protected:
-        enum RegisterContants
-        {
-            NumGDBRegs
-            //XXX fill this in
-        };
+        GDB32_EAX,
+        GDB32_ECX,
+        GDB32_EDX,
+        GDB32_EBX,
+        GDB32_ESP,
+        GDB32_EBP,
+        GDB32_ESI,
+        GDB32_EDI,
+        GDB32_EIP,
+        GDB32_EFLAGS,
+        GDB32_CS,
+        GDB32_SS,
+        GDB32_DS,
+        GDB32_ES,
+        GDB32_FS,
+        GDB32_GS,
 
-      public:
-        RemoteGDB(System *system, ThreadContext *context);
+        GDB32_NUMREGS
+    };
+
+    enum
+    {
+        GDB64_RAX,
+        GDB64_RBX,
+        GDB64_RCX,
+        GDB64_RDX,
+        GDB64_RSI,
+        GDB64_RDI,
+        GDB64_RBP,
+        GDB64_RSP,
+        GDB64_R8,
+        GDB64_R9,
+        GDB64_R10,
+        GDB64_R11,
+        GDB64_R12,
+        GDB64_R13,
+        GDB64_R14,
+        GDB64_R15,
+        GDB64_RIP,
+        // These indices index into the reg cache treated as an array of 32
+        // bit integers. The next index is one beyond the previous, and then
+        // scaled up from an index into an array of 64 bit integers.
+        GDB64_RFLAGS_32 = (GDB64_RIP + 1) * 2,
+        GDB64_CS_32,
+        GDB64_SS_32,
+        GDB64_DS_32,
+        GDB64_ES_32,
+        GDB64_FS_32,
+        GDB64_GS_32,
+
+        // Scale the end index count back down (rounded up) to be for an
+        // array of 64 bit integers.
+        GDB64_NUMREGS = (GDB64_GS_32 + 1) / 2 + 1
+    };
 
-        bool acc(Addr addr, size_t len);
+    RemoteGDB(System *system, ThreadContext *context);
 
+    bool acc(Addr addr, size_t len);
+
+  protected:
+    class SingleStepEvent : public Event
+    {
       protected:
-        void getregs();
-        void setregs();
+        RemoteGDB *gdb;
 
-        void clearSingleStep();
-        void setSingleStep();
+      public:
+        SingleStepEvent(RemoteGDB *g) : gdb(g)
+        {}
 
-        Addr nextBkpt;
+        void process();
     };
+
+    SingleStepEvent singleStepEvent;
+
+    void getregs();
+    void setregs();
+
+    void clearSingleStep();
+    void setSingleStep();
+
+    bool checkBpLen(size_t len) { return len == 1; }
+};
+
+const int GDB_REG_BYTES =
+    std::max(RemoteGDB::GDB32_NUMREGS * sizeof(uint32_t),
+             RemoteGDB::GDB64_NUMREGS * sizeof(uint64_t));
+
 }
 
 #endif // __ARCH_X86_REMOTEGDB_HH__