diff options
Diffstat (limited to 'model')
| -rw-r--r-- | model/riscv_ext_regs.sail | 15 | ||||
| -rw-r--r-- | model/riscv_insts_zicsr.sail | 2 |
2 files changed, 17 insertions, 0 deletions
diff --git a/model/riscv_ext_regs.sail b/model/riscv_ext_regs.sail index 9ff83b3..b03ecd5 100644 --- a/model/riscv_ext_regs.sail +++ b/model/riscv_ext_regs.sail @@ -12,3 +12,18 @@ to omnipotent instead of null). */ val ext_rvfi_init : unit -> unit effect {wreg} function ext_rvfi_init () = () + + +/*! +THIS(csrno, priv, isWrite) allows an extension to block access to csrno, +at Privilege level priv. It should return true if the access is allowed. +*/ +val ext_check_CSR : (bits(12), Privilege, bool) -> bool +function ext_check_CSR (csrno, p, isWrite) = true + +/*! +THIS is called if ext_check_CSR returns false. It should +cause an appropriate RISCV exception. + */ +val ext_check_CSR_fail : unit->unit +function ext_check_CSR_fail () = () diff --git a/model/riscv_insts_zicsr.sail b/model/riscv_insts_zicsr.sail index dd8a4a0..056f537 100644 --- a/model/riscv_insts_zicsr.sail +++ b/model/riscv_insts_zicsr.sail @@ -179,6 +179,8 @@ function clause execute CSR(csr, rs1, rd, is_imm, op) = { }; if ~ (check_CSR(csr, cur_privilege, isWrite)) then { handle_illegal(); RETIRE_FAIL } + else if ~ (ext_check_CSR(csr, cur_privilege, isWrite)) + then { ext_check_CSR_fail(); RETIRE_FAIL } else { let csr_val = readCSR(csr); /* could have side-effects, so technically shouldn't perform for CSRW[I] with rd == 0 */ if isWrite then { |