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Simplify PMP code #738

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Simplify PMP code #738

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17 changes: 3 additions & 14 deletions model/riscv_pmp_control.sail
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Original file line number Diff line number Diff line change
Expand Up @@ -39,25 +39,14 @@ function pmpAddrRange(cfg: Pmpcfg_ent, pmpaddr: xlenbits, prev_pmpaddr: xlenbits
/* permission checks */

val pmpCheckRWX: (Pmpcfg_ent, AccessType(ext_access_type)) -> bool
function pmpCheckRWX(ent, acc) = {
function pmpCheckRWX(ent, acc) =
match acc {
Read(_) => ent[R] == 0b1,
Write(_) => ent[W] == 0b1,
ReadWrite(_) => ent[R] == 0b1 & ent[W] == 0b1,
Execute() => ent[X] == 0b1
Execute() => ent[X] == 0b1,
}
}

// this needs to be called with the effective current privilege.
val pmpCheckPerms: (Pmpcfg_ent, AccessType(ext_access_type), Privilege) -> bool
function pmpCheckPerms(ent, acc, priv) = {
match priv {
Machine => if pmpLocked(ent)
then pmpCheckRWX(ent, acc)
else true,
_ => pmpCheckRWX(ent, acc)
}
}

/* matching logic */

Expand Down Expand Up @@ -95,7 +84,7 @@ function pmpMatchEntry(addr: physaddr, width: xlenbits, acc: AccessType(ext_acce
match pmpMatchAddr(addr, width, rng) {
PMP_NoMatch => PMP_Continue,
PMP_PartialMatch => PMP_Fail,
PMP_Match => if pmpCheckPerms(ent, acc, priv)
PMP_Match => if pmpCheckRWX(ent, acc) | (priv == Machine & not(pmpLocked(ent)))
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I guess the other options would be

  1. pass priv to pmpcheckRWX() and add if priv == Machine & not(pmpLocked(ent)) then true else match ...?
  2. change pmpCheckPerms to an if instead of a match().

But 2) seems unnecessary since there is only one caller of pmpCheckPerms() so we might as inline it. LGTM.

then PMP_Success
else PMP_Fail
}
Expand Down
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