Cheri-research/cheri-cap-lib
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Fold in some comments from jdw57 and pdr32

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gameboo
2021-09-28 12:42:17 +01:00
parent 6e20d177dc
commit aa0a8fe224
2 changed files with 25 additions and 32 deletions
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41
CHERICap.bsv
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@@ -139,6 +139,11 @@ endinstance
// CHERI capability typeclass
////////////////////////////////////////////////////////////////////////////////
// Note: Some class methods receive a "dummy" capability as a type proxy
// argument. This is useful for methods to know which capability format is
// being operated on without requiring a specific capability value.
// (A more elegant way to achieve this would be to use something along the
// lines of haskell's "@type" type application mechanism)
typeclass CHERICap #( type capT // type of the CHERICap capability
, numeric type otypeW // width of the object type
@@ -193,7 +198,7 @@ typeclass CHERICap #( type capT // type of the CHERICap capability
function Kind #(otypeW) getKind (capT cap);
// set the kind of a capability
function capT setKind (capT cap, Kind #(otypeW) kind);
// XXX TODO Check if a type is valid
// Check if a type is valid (requires a dummy proxy)
function Bool validAsType (capT dummy, Bit #(addrW) checkType);
// capability in-memory architectural representation
@@ -274,46 +279,38 @@ typeclass CHERICap #( type capT // type of the CHERICap capability
, zeroExtend (getRepBase (cap))
, getRepTop (cap)
, isRepTopIncluded );
// XXX TODO Check the alignment of the base, giving least significant 2 bits.
// This relies on the fact that internal exponents take up 2 bits of the
// base.
function Bit #(2) getBaseAlignment (capT cap);
// XXX TODO Get representable alignment mask
function Bit #(addrW) getRepresentableAlignmentMask ( capT dummy
, Bit #(addrW) lenReq) =
setBoundsCombined (nullCapFromDummy (dummy), lenReq).mask;
// XXX TODO Get representable length
function Bit #(addrW) getRepresentableLength ( capT dummy
, Bit #(addrW) lenReq) =
setBoundsCombined (nullCapFromDummy (dummy), lenReq).length;
// Check the alignment of the base, giving least significant 2 bits.
function Bit #(2) getBaseAlignment (capT cap) = getBoundsInfo (cap).base[1:0];
// capability derivation (bounds set)
//////////////////////////////////////////////////////////////////////////////
// Set the length of the capability
function SetBoundsReturn #(capT, addrW)
setBoundsCombined (capT cap, Bit #(addrW) length);
// Set the length of the capability. Inexact: result length may be different
// to requested
function Exact #(capT) setBounds (capT cap, Bit #(addrW) length);
let combinedResult = setBoundsCombined (cap, length);
return Exact {exact: combinedResult.exact, value: combinedResult.cap};
endfunction
// XXX TODO
function SetBoundsReturn #(capT, addrW)
setBoundsCombined (capT cap, Bit #(addrW) length);
// Round a requested length (requires a dummy proxy)
function Bit #(addrW) roundLength (capT dummy, Bit #(addrW) reqLength) =
setBoundsCombined (nullCapFromDummy (dummy), reqLength).length;
// Get alignment mask for a requested length (requires a dummy proxy)
function Bit #(addrW) alignmentMask (capT dummy, Bit #(addrW) reqLength) =
setBoundsCombined (nullCapFromDummy (dummy), reqLength).mask;
// common capabilities
//////////////////////////////////////////////////////////////////////////////
// the null capability
function capT nullCap = nullCapFromDummy(?);
function capT nullCap = nullCapFromDummy (?);
// a null capability with a given address set
function capT nullWithAddr (Bit #(addrW) addr);
// maximally permissive capability (initial register state)
function capT almightyCap;
// XXX TODO Workaround to allow null cap to be derived in default
// implementations
// the null capability (requires a dummy proxy)
function capT nullCapFromDummy (capT dummy);
// Assert that the encoding is valid