Fixed an issue where return sentries weren't being sealed properly.

PiperOrigin-RevId: 707173405
Change-Id: Ia126d4ef1eac55cd521f06a0d455925a5fbe2366

cheriot/mpact_cheriot.cc

diff --git a/cheriot/mpact_cheriot.cc b/cheriot/mpact_cheriot.cc
index ef14699..74efd2c 100644
--- a/cheriot/mpact_cheriot.cc
+++ b/cheriot/mpact_cheriot.cc
@@ -82,7 +82,7 @@
 using ::mpact::sim::util::TaggedMemoryUseProfiler;
 
 // Flat to specify core version.
-ABSL_FLAG(int, core_version, 100, "Core version");
+ABSL_FLAG(int, core_version, 50, "Core version");
 // Flags for specifying interactive mode.
 ABSL_FLAG(bool, i, false, "Interactive mode");
 ABSL_FLAG(bool, interactive, false, "Interactive mode");

cheriot/riscv_cheriot_instructions.cc

diff --git a/cheriot/riscv_cheriot_instructions.cc b/cheriot/riscv_cheriot_instructions.cc
index 06d20a1..d1b1637 100644
--- a/cheriot/riscv_cheriot_instructions.cc
+++ b/cheriot/riscv_cheriot_instructions.cc
@@ -518,6 +518,8 @@
     case CapReg::kInterruptInheritingSentry:
     case CapReg::kInterruptDisablingForwardSentry:
     case CapReg::kInterruptEnablingForwardSentry:
+    case CapReg::kInterruptDisablingBackwardSentry:
+    case CapReg::kInterruptEnablingBackwardSentry:
     case CapReg::kSealedExecutable6:
     case CapReg::kSealedExecutable7:
       permitted_otype = cs1->HasPermission(CapReg::kPermitExecute);

cheriot/test/riscv_cheriot_instructions_test.cc

diff --git a/cheriot/test/riscv_cheriot_instructions_test.cc b/cheriot/test/riscv_cheriot_instructions_test.cc
index 3271a58..2a10c91 100644
--- a/cheriot/test/riscv_cheriot_instructions_test.cc
+++ b/cheriot/test/riscv_cheriot_instructions_test.cc
@@ -1452,6 +1452,8 @@
     if ((o_type == OT::kInterruptInheritingSentry) ||
         (o_type == OT::kInterruptDisablingForwardSentry) ||
         (o_type == OT::kInterruptEnablingForwardSentry) ||
+        (o_type == OT::kInterruptDisablingBackwardSentry) ||
+        (o_type == OT::kInterruptEnablingBackwardSentry) ||
         (o_type == OT::kSealedExecutable6) ||
         (o_type == OT::kSealedExecutable7)) {
       EXPECT_TRUE(c3_reg()->tag());