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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 */
/*=======================================================================================*/
/*
* Types used in supporting extensions for page-table walks.
*
* There are three types involved:
*
* . An accumulator, passed down from the root to the leaves (ext_ptw)
* . Metadata returned with failed permissions checks (ext_ptw_fail)
* . Errors embedded within the PTW_Error union
*
* Information flow begins with init_ext_ptw (: ext_ptw) being routed,
* via the translateNN functions and/or walkNN functions, to the
* checkPTEPermission function, which is the intended point of
* interaction with extensions.
*
* checkPTEPermission will be called repeatedly at each PTE, each call
* seeing the accumulator state generated by a successful result of
* the previous call. On failure, this function is expected to
* generate, instead, an ext_ptw_fail value as well as a new
* accumulator value, both of which will be returned to the code
* calling into translation.
*
* If translation ultimately succeeds, the final accumulator state is
* captured and will be returned to the code calling into translation.
*
* If translation ultimately fails, the accumulator at the time of
* failure and the ext_ptw_fail value are returned to the caller. The
* ext_ptw_fail value is used to generate a PTW_Error value by calling
* ext_get_ptw_error; this allows the extension to generate both novel
* (e.g., PTW_Ext_Error) and existing (e.g., PTW_Invalid_PTE) PTW_Error
* values.
*/
type ext_ptw = unit
let init_ext_ptw : ext_ptw = ()
type ext_ptw_fail = unit
/* This type can be used for custom errors for page-table-walks,
* and values in this type are typically generated from the final
* result of the ext_ptw at the end of the walk.
*/
type ext_ptw_error = unit /* No extensions for page-table-walk errors */
/* This type supports extensions to the exceptions defined in the ISA. */
type ext_exc_type = unit /* No exception extensions */
/* Default translation of PTW errors into exception annotations */
function ext_translate_exception(e : ext_ptw_error) -> ext_exc_type =
e /* type pun because both are unit; extensions may need to override this */
/* Default conversion of extension exceptions to bits */
val ext_exc_type_to_bits : ext_exc_type -> exc_code
function ext_exc_type_to_bits(e) = 0x18 /* First code for a custom extension */
/* Default conversion of extension exceptions to integers */
val num_of_ext_exc_type : ext_exc_type -> {'n, (0 <= 'n < xlen). int('n)}
function num_of_ext_exc_type(e) = 24 /* First code for a custom extension */
/* Default conversion of extension exceptions to strings */
val ext_exc_type_to_str : ext_exc_type -> string
function ext_exc_type_to_str(e) = "extension-exception"
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