ARM: Fix checkpoint restoration into O3 CPU and the way O3 switchCpu works.

This change fixes a small bug in the arm copyRegs() code where some registers
wouldn't be copied if the processor was in a mode other than MODE_USER.
Additionally, this change simplifies the way the O3 switchCpu code works by
utilizing TheISA::copyRegs() to copy the required context information
rather than the adhoc copying that goes on in the CPU model. The current code
makes assumptions about the visibility of int and float registers that aren't
true for all architectures in FS mode.

3 files changed, 23 insertions, 1 deletions

diff --git a/src/arch/arm/isa.cc b/src/arch/arm/isa.cc
index 216ae04e7..9988d431a 100644
--- a/src/arch/arm/isa.cc
+++ b/src/arch/arm/isa.cc
@@ -447,6 +447,7 @@ ISA::setMiscReg(int misc_reg, const MiscReg &val, ThreadContext *tc)
                   default:
                       panic("Security Extensions not implemented!");
               }
+              warn("Translating via MISCREG in atomic mode! Fix Me!\n");
               req->setVirt(0, val, 1, flags, tc->pcState().pc());
               fault = tc->getDTBPtr()->translateAtomic(req, tc, mode);
               if (fault == NoFault) {
@@ -475,7 +476,13 @@ ISA::setMiscReg(int misc_reg, const MiscReg &val, ThreadContext *tc)
             tc->getITBPtr()->invalidateMiscReg();
             tc->getDTBPtr()->invalidateMiscReg();
             break;
-
+          case MISCREG_CPSR_MODE:
+            // This miscreg is used by copy*Regs to set the CPSR mode
+            // without updating other CPSR variables. It's used to
+            // make sure the register map is in such a state that we can
+            // see all of the registers for the copy.
+            updateRegMap(val);
+            return;
         }
     }
     setMiscRegNoEffect(misc_reg, newVal);
diff --git a/src/arch/arm/miscregs.hh b/src/arch/arm/miscregs.hh
index fc18fa114..2ccd9b4c2 100644
--- a/src/arch/arm/miscregs.hh
+++ b/src/arch/arm/miscregs.hh
@@ -170,6 +170,7 @@ namespace ArmISA
         MISCREG_ID_ISAR3,
         MISCREG_ID_ISAR4,
         MISCREG_ID_ISAR5,
+        MISCREG_CPSR_MODE,
         MISCREG_CP15_UNIMP_START,
         MISCREG_TCMTR = MISCREG_CP15_UNIMP_START,
         MISCREG_ID_PFR1,
@@ -233,6 +234,7 @@ namespace ArmISA
         "pmceid1", "pmc_other", "pmxevcntr",
         "pmuserenr", "pmintenset", "pmintenclr",
         "id_isar0", "id_isar1", "id_isar2", "id_isar3", "id_isar4", "id_isar5",
+        "cpsr_mode",
          // Unimplemented below
         "tcmtr",
         "id_pfr1", "id_dfr0", "id_afr0",
diff --git a/src/arch/arm/utility.cc b/src/arch/arm/utility.cc
index 0d91c9f90..6bca63291 100644
--- a/src/arch/arm/utility.cc
+++ b/src/arch/arm/utility.cc
@@ -124,8 +124,21 @@ void
 copyRegs(ThreadContext *src, ThreadContext *dest)
 {
     int i;
+
+    int saved_mode = ((CPSR)src->readMiscReg(MISCREG_CPSR)).mode;
+
+    // Make sure we're in user mode, so we can easily see all the registers
+    // in the copy loop
+    src->setMiscReg(MISCREG_CPSR_MODE, MODE_USER);
+    dest->setMiscReg(MISCREG_CPSR_MODE, MODE_USER);
+
     for(i = 0; i < TheISA::NumIntRegs; i++)
         dest->setIntReg(i, src->readIntReg(i));
+
+    // Restore us back to the old mode
+    src->setMiscReg(MISCREG_CPSR_MODE, saved_mode);
+    dest->setMiscReg(MISCREG_CPSR_MODE, saved_mode);
+
     for(i = 0; i < TheISA::NumFloatRegs; i++)
         dest->setFloatReg(i, src->readFloatReg(i));
     for(i = 0; i < TheISA::NumMiscRegs; i++)