Allow fixed endianness to be observed through MBE/SBE/UBE

riscv/encoding.h

@@ -9,7 +9,7 @@
 #define MSTATUS_MIE         0x00000008
 #define MSTATUS_UPIE        0x00000010
 #define MSTATUS_SPIE        0x00000020
-#define MSTATUS_HPIE        0x00000040
+#define MSTATUS_UBE         0x00000040
 #define MSTATUS_MPIE        0x00000080
 #define MSTATUS_SPP         0x00000100
 #define MSTATUS_VS          0x00000600
@@ -25,14 +25,20 @@
 #define MSTATUS32_SD        0x80000000
 #define MSTATUS_UXL         0x0000000300000000
 #define MSTATUS_SXL         0x0000000C00000000
+#define MSTATUS_SBE         0x0000001000000000
+#define MSTATUS_MBE         0x0000002000000000
 #define MSTATUS_GVA         0x0000004000000000
 #define MSTATUS_MPV         0x0000008000000000
 #define MSTATUS64_SD        0x8000000000000000
 
+#define MSTATUSH_SBE        0x00000010
+#define MSTATUSH_MBE        0x00000020
+
 #define SSTATUS_UIE         0x00000001
 #define SSTATUS_SIE         0x00000002
 #define SSTATUS_UPIE        0x00000010
 #define SSTATUS_SPIE        0x00000020
+#define SSTATUS_UBE         0x00000040
 #define SSTATUS_SPP         0x00000100
 #define SSTATUS_VS          0x00000600
 #define SSTATUS_FS          0x00006000

riscv/processor.cc

@@ -446,6 +446,10 @@ void processor_t::enable_log_commits()
 void processor_t::reset()
 {
   state.reset(max_isa);
+#ifdef RISCV_ENABLE_DUAL_ENDIAN
+  if (mmu->is_target_big_endian())
+    state.mstatus |= MSTATUS_UBE | MSTATUS_SBE | MSTATUS_MBE;
+#endif
 
   state.mideleg = supports_extension('H') ? MIDELEG_FORCED_MASK : 0;
 
@@ -1411,8 +1415,8 @@ reg_t processor_t::get_csr(int which, insn_t insn, bool write, bool peek)
       ret(state.mcounteren);
     case CSR_MCOUNTINHIBIT: ret(0);
     case CSR_SSTATUS: {
-      reg_t mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_SPP | SSTATUS_FS
+      reg_t mask = SSTATUS_SIE | SSTATUS_SPIE | SSTATUS_UBE | SSTATUS_SPP
-                 | (supports_extension('V') ? SSTATUS_VS : 0)
+                 | SSTATUS_FS | (supports_extension('V') ? SSTATUS_VS : 0)
                  | SSTATUS_XS | SSTATUS_SUM | SSTATUS_MXR | SSTATUS_UXL;
       reg_t sstatus = state.mstatus & mask;
       if ((sstatus & SSTATUS_FS) == SSTATUS_FS ||
@@ -1486,6 +1490,10 @@ reg_t processor_t::get_csr(int which, insn_t insn, bool write, bool peek)
       }
     }
     case CSR_MSTATUS: ret(state.mstatus);
+    case CSR_MSTATUSH:
+      if (xlen == 32)
+        ret((state.mstatus >> 32) & (MSTATUSH_SBE | MSTATUSH_MBE));
+      break;
     case CSR_MIP: ret(state.mip);
     case CSR_MIE: ret(state.mie);
     case CSR_MEPC: ret(state.mepc & pc_alignment_mask());

riscv/sim.cc

@@ -350,6 +350,7 @@ void sim_t::set_target_endianness(memif_endianness_t endianness)
   debug_mmu->set_target_big_endian(enable);
   for (size_t i = 0; i < procs.size(); i++) {
     procs[i]->get_mmu()->set_target_big_endian(enable);
+    procs[i]->reset();
   }
 #else
   assert(endianness == memif_endianness_little);