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/*=======================================================================================*/
/* This Sail RISC-V architecture model, comprising all files and */
/* directories except where otherwise noted is subject the BSD */
/* two-clause license in the LICENSE file. */
/* */
/* SPDX-License-Identifier: BSD-2-Clause */
/*=======================================================================================*/
/* default exception model */
type ext_exception = unit
/* Is XRET from given mode permitted by extension? */
function ext_check_xret_priv (p : Privilege) : Privilege -> bool = true
/* Called if above check fails */
function ext_fail_xret_priv () : unit -> unit = ()
function handle_trap_extension(p : Privilege, pc : xlenbits, u : option(unit)) -> unit = ()
/* used for traps and ECALL */
function prepare_trap_vector(p : Privilege, cause : Mcause) -> xlenbits = {
let tvec : Mtvec = match p {
Machine => mtvec,
Supervisor => stvec,
User => utvec
};
match tvec_addr(tvec, cause) {
Some(epc) => epc,
None() => internal_error(__FILE__, __LINE__, "Invalid tvec mode")
}
}
/* xRET handling involves three functions:
*
* get_xret_target: used to read the value of the xret target (no control flow transfer)
* set_xret_target: used to write a value of the xret target (no control flow transfer)
* prepare_xret_target: used to get the value for control transfer to the xret target
*/
val get_xret_target : Privilege -> xlenbits
function get_xret_target(p) =
match p {
Machine => mepc,
Supervisor => sepc,
User => uepc
}
val set_xret_target : (Privilege, xlenbits) -> xlenbits
function set_xret_target(p, value) = {
let target = legalize_xepc(value);
match p {
Machine => mepc = target,
Supervisor => sepc = target,
User => uepc = target
};
target
}
val prepare_xret_target : (Privilege) -> xlenbits
function prepare_xret_target(p) =
get_xret_target(p)
/* other trap-related CSRs */
function get_mtvec() -> xlenbits =
mtvec.bits
function get_stvec() -> xlenbits =
stvec.bits
function get_utvec() -> xlenbits =
utvec.bits
function set_mtvec(value : xlenbits) -> xlenbits = {
mtvec = legalize_tvec(mtvec, value);
mtvec.bits
}
function set_stvec(value : xlenbits) -> xlenbits = {
stvec = legalize_tvec(stvec, value);
stvec.bits
}
function set_utvec(value : xlenbits) -> xlenbits = {
utvec = legalize_tvec(utvec, value);
utvec.bits
}
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