The senvcfg.SSE will read (only) as zero when menvcfg.SSE is 0

Author: binno

riscv/csrs.cc

@@ -1561,6 +1561,18 @@ void senvcfg_csr_t::verify_permissions(insn_t insn, bool write) const {
   masked_csr_t::verify_permissions(insn, write);
 }
 
+// senvcfg.sse is read_only 0 when menvcfg.sse = 0
+reg_t senvcfg_csr_t::read() const noexcept {
+  reg_t envcfg = state->v ? state->henvcfg->read() : state->menvcfg->read();
+  return masked_csr_t::read() & ~(envcfg & MENVCFG_SSE ? 0 : MENVCFG_SSE);
+}
+
+bool senvcfg_csr_t::unlogged_write(const reg_t val) noexcept {
+  reg_t envcfg = state->v ? state->henvcfg->read() : state->menvcfg->read();
+  const reg_t mask = envcfg | ~MENVCFG_SSE;
+  return envcfg_csr_t::unlogged_write((masked_csr_t::read() & ~mask) | (val & mask));
+}
+
 void henvcfg_csr_t::verify_permissions(insn_t insn, bool write) const {
   if (proc->extension_enabled(EXT_SMSTATEEN)) {
     if ((state->prv < PRV_M) && !(state->mstateen[0]->read() & MSTATEEN0_HENVCFG))
@@ -1571,7 +1583,7 @@ void henvcfg_csr_t::verify_permissions(insn_t insn, bool write) const {
 }
 
 bool henvcfg_csr_t::unlogged_write(const reg_t val) noexcept {
-  const reg_t mask = menvcfg->read() | ~(MENVCFG_PBMTE | MENVCFG_STCE | MENVCFG_ADUE | MENVCFG_DTE);
+  const reg_t mask = menvcfg->read() | ~(MENVCFG_PBMTE | MENVCFG_STCE | MENVCFG_ADUE | MENVCFG_DTE | MENVCFG_SSE);
   return envcfg_csr_t::unlogged_write((masked_csr_t::read() & ~mask) | (val & mask));
 }
 

riscv/csrs.h

@@ -479,14 +479,13 @@ class envcfg_csr_t: public masked_csr_t {
 // henvcfg.stce is read_only 0 when menvcfg.stce = 0
 // henvcfg.hade is read_only 0 when menvcfg.hade = 0
 // henvcfg.dte is read_only 0 when menvcfg.dte = 0
+// henvcfg.sse is read_only 0 when menvcfg.sse = 0
 class henvcfg_csr_t final: public envcfg_csr_t {
  public:
   henvcfg_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init, csr_t_p menvcfg);
-
   reg_t read() const noexcept override {
-    return (menvcfg->read() | ~(MENVCFG_PBMTE | MENVCFG_STCE | MENVCFG_ADUE | MENVCFG_DTE)) & masked_csr_t::read();
+    return (menvcfg->read() | ~(MENVCFG_PBMTE | MENVCFG_STCE | MENVCFG_ADUE | MENVCFG_DTE | MENVCFG_SSE)) & masked_csr_t::read();
   }
-
   virtual void verify_permissions(insn_t insn, bool write) const override;
 
  protected:
@@ -786,7 +785,11 @@ class sstateen_csr_t: public hstateen_csr_t {
 class senvcfg_csr_t final: public envcfg_csr_t {
  public:
   senvcfg_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init);
+  reg_t read() const noexcept override;
   virtual void verify_permissions(insn_t insn, bool write) const override;
+
+ protected:
+  virtual bool unlogged_write(const reg_t val) noexcept override;
 };
 
 class stimecmp_csr_t: public basic_csr_t {