From 35fae4baa4206d1cc3fe43a6dfb8d167dcb9bd5a Mon Sep 17 00:00:00 2001 From: ahadali5000 Date: Mon, 3 Jul 2023 10:58:32 +0500 Subject: [PATCH] If C cannot be disabled, all changes to misa must be suppressed --- model/riscv_sys_regs.sail | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/model/riscv_sys_regs.sail b/model/riscv_sys_regs.sail index ecc7735b7..35169b106 100644 --- a/model/riscv_sys_regs.sail +++ b/model/riscv_sys_regs.sail @@ -156,22 +156,19 @@ val sys_enable_next = {c: "sys_enable_next", ocaml: "Platform.enable_next", _: " unsetting C. If it returns true the write will have no effect. */ val ext_veto_disable_C : unit -> bool effect {rreg} -/* We currently only support dynamic changes for the C extension. */ function legalize_misa(m : Misa, v : xlenbits) -> Misa = { - if sys_enable_writable_misa () - then { /* Handle modifications to C. */ - let v = Mk_Misa(v); - /* Suppress changing C if nextPC would become misaligned or an extension vetoes or C was disabled at boot (i.e. not supported). */ - let m = - if (v.C() == 0b0 & (nextPC[1] == bitone | ext_veto_disable_C())) | not(sys_enable_rvc()) - then m - else update_C(m, v.C()); - /* Handle updates for F/D. */ - if not(sys_enable_fdext()) | (v.D() == 0b1 & v.F() == 0b0) - then m - else update_D(update_F(m, v.F()), v.D()) - } - else m + let v = Mk_Misa(v); + /* If MISA is not writable then suppress updates to misa & disabling C if nextPC would become misaligned or an extension vetoes */ + if not(sys_enable_writable_misa()) | (v.C() == 0b0 & (nextPC[1] == bitone | ext_veto_disable_C())) + then m + else { + /* Suppress updates to C if C is read-only */ + let m = if not(sys_enable_rvc()) then m else update_C(m, v.C()); + /* Handle updates for F/D. */ + if not(sys_enable_fdext()) | (v.D() == 0b1 & v.F() == 0b0) + then m + else update_D(update_F(m, v.F()), v.D()) + } } /* helpers to check support for various extensions. */