Merge pull request #1640 from YenHaoChen/pr-henvcfg

Ignore writes to henvcfg fields (PBMTE, STCE, and ADUE) when read-only 0

Author: aswaterman

riscv/csrs.cc

@@ -1549,6 +1549,11 @@ void henvcfg_csr_t::verify_permissions(insn_t insn, bool write) const {
   masked_csr_t::verify_permissions(insn, write);
 }
 
+bool henvcfg_csr_t::unlogged_write(const reg_t val) noexcept {
+  const reg_t mask = menvcfg->read() | ~(MENVCFG_PBMTE | MENVCFG_STCE | MENVCFG_ADUE);
+  return envcfg_csr_t::unlogged_write((masked_csr_t::read() & ~mask) | (val & mask));
+}
+
 stimecmp_csr_t::stimecmp_csr_t(processor_t* const proc, const reg_t addr, const reg_t imask):
   basic_csr_t(proc, addr, 0), intr_mask(imask) {
 }

riscv/csrs.h

@@ -490,6 +490,9 @@ class henvcfg_csr_t final: public envcfg_csr_t {
 
   virtual void verify_permissions(insn_t insn, bool write) const override;
 
+ protected:
+  virtual bool unlogged_write(const reg_t val) noexcept override;
+
  private:
   csr_t_p menvcfg;
 };