csrs.cc: if no U-mode, mstatus.tw is read-only 0

7 months ago · 4c10fbe07b
1 changed files with 2 additions and 1 deletions
--- a/riscv/csrs.cc
+++ b/riscv/csrs.cc
@ -556,7 +556,8 @@ bool mstatus_csr_t::unlogged_write(const reg_t val) noexcept {
  const reg_t mask = adj_write_mask
                   | MSTATUS_MIE | MSTATUS_MPIE
                   | (proc->extension_enabled('U') ? MSTATUS_MPRV : 0)
-                   | MSTATUS_MPP | MSTATUS_TW
+                   | MSTATUS_MPP
+                   | (proc->extension_enabled('U') ? MSTATUS_TW : 0)
                   | (proc->extension_enabled('S') ? MSTATUS_TSR : 0)
                   | (has_page ? MSTATUS_TVM : 0)
                   | (has_gva ? MSTATUS_GVA : 0)