arch-arm: ArmSystem::resetAddr64 renamed to be used in AArch32

ARMv8 differs from ARMv7 with the presence of RVBAR register, which
contains the implementation defined reset address when EL3 is not
implemented.
The entry 0x0 in the AArch32 vector table, once used for the Reset
Vector, is now marked as "Not used", stating that it is now IMPLEMENTATION
DEFINED. An implementation might still use this vector table entry to
hold the Reset vector, but having a Reset address != than the general
vector table (for any other exception) is allowed.

At the moment any Reset exception is still using 0 as a vector table
base address. This patch is extending the ArmSystem::resetAddr64 to
ArmSystem::resetAddr so that it can be used for initializing
MVBAR/RVBAR. In order to do so, we are providing a specialized behavior
for the Reset exception when evaluating the vector base address.

Change-Id: I051a730dc089e194db3b107bbed19251c661f87e
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/14000
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

1 files changed, 23 insertions, 6 deletions

diff --git a/src/arch/arm/faults.cc b/src/arch/arm/faults.cc
index bd06ea288..665b2989c 100644
--- a/src/arch/arm/faults.cc
+++ b/src/arch/arm/faults.cc
@@ -297,12 +297,9 @@ ArmFault::getVector(ThreadContext *tc)
 {
     Addr base;
 
-    // ARM ARM issue C B1.8.1
-    bool haveSecurity = ArmSystem::haveSecurity(tc);
-
     // Check for invalid modes
     CPSR cpsr = tc->readMiscRegNoEffect(MISCREG_CPSR);
-    assert(haveSecurity                      || cpsr.mode != MODE_MON);
+    assert(ArmSystem::haveSecurity(tc) || cpsr.mode != MODE_MON);
     assert(ArmSystem::haveVirtualization(tc) || cpsr.mode != MODE_HYP);
 
     switch (cpsr.mode)
@@ -318,10 +315,12 @@ ArmFault::getVector(ThreadContext *tc)
         if (sctlr.v) {
             base = HighVecs;
         } else {
-            base = haveSecurity ? tc->readMiscReg(MISCREG_VBAR) : 0;
+            base = ArmSystem::haveSecurity(tc) ?
+                tc->readMiscReg(MISCREG_VBAR) : 0;
         }
         break;
     }
+
     return base + offset(tc);
 }
 
@@ -694,6 +693,24 @@ ArmFault::invoke64(ThreadContext *tc, const StaticInstPtr &inst)
         setSyndrome(tc, getSyndromeReg64());
 }
 
+Addr
+Reset::getVector(ThreadContext *tc)
+{
+    Addr base;
+
+    // Check for invalid modes
+    CPSR M5_VAR_USED cpsr = tc->readMiscRegNoEffect(MISCREG_CPSR);
+    assert(ArmSystem::haveSecurity(tc) || cpsr.mode != MODE_MON);
+    assert(ArmSystem::haveVirtualization(tc) || cpsr.mode != MODE_HYP);
+
+    // RVBAR is aliased (implemented as) MVBAR in gem5, since the two
+    // are mutually exclusive; there is no need to check here for
+    // which register to use since they hold the same value
+    base = tc->readMiscReg(MISCREG_MVBAR);
+
+    return base + offset(tc);
+}
+
 void
 Reset::invoke(ThreadContext *tc, const StaticInstPtr &inst)
 {
@@ -715,7 +732,7 @@ Reset::invoke(ThreadContext *tc, const StaticInstPtr &inst)
         }
     } else {
         // Advance the PC to the IMPLEMENTATION DEFINED reset value
-        PCState pc = ArmSystem::resetAddr64(tc);
+        PCState pc = ArmSystem::resetAddr(tc);
         pc.aarch64(true);
         pc.nextAArch64(true);
         tc->pcState(pc);