Cheri-research/cheri-cap-lib
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Fixes for CRAM and SetAddress.

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The SetAddress issue and fix were found and verified (respectively) to some degree by TestRIG.
This commit is contained in:
Jonathan Woodruff
2020-03-05 11:50:07 +00:00
parent ebac2cdf6d
commit 22434499e5
1 changed files with 5 additions and 8 deletions
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13
CHERICC_Fat.bsv
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@@ -524,7 +524,7 @@ function SetBoundsReturn setBoundsFat(CapFat cap, Address lengthFull);
newLengthRounded = (newLengthRounded & (~lmaskLor));
if (lostSignificantLen) newLength = newLengthRounded;
end
LCapAddress baseMask = ~lmaskLor;
LCapAddress baseMask = (lengthIsMax && lostSignificantTop) ? ~lmaskLo:~lmaskLor;
// Return derived capability
return SetBoundsReturn{cap: ret, exact: exact, length: truncate(newLength), mask: truncate(baseMask)};
@@ -660,18 +660,15 @@ function VnD#(CapFat) incOffsetFat(CapFat cap, LCapAddress pointer, Bit#(CapAddr
return VnD {v: inBounds, d: ret};
endfunction
function VnD#(CapFat) setAddress(CapFat cap, LCapAddress address, TempFields tf);
CapFat ret = cap;
CapFat ret = setCapPointer(cap, address);
Exp e = cap.bounds.exp;
ret.address = address;
ret.addrBits = truncate(address >> e);
// Calculate what the upper bits of the new address must be if it is to be in representable bounds.
Bool newAddrHi = truncateLSB(ret.addrBits) < tf.repBoundTopBits;
// Shift amount needed to look at only the bits above the mantissa.
Exp toUpperBits = e + fromInteger(valueOf(MW));
Bit#(TAdd#(CapAddressW,4)) mask = -1 << toUpperBits;
Bit#(TAdd#(CapAddressW,4)) newAddrDiff = (zeroExtend(cap.address)&mask) - (zeroExtend(address)&mask);
CapAddress mask = -1 << toUpperBits;
CapAddress newAddrDiff = (truncate(cap.address)&mask) - (truncate(address)&mask);
// Assert that the bits above the mantissa are all equal.
Bit#(1) msb = truncateLSB(newAddrDiff);
Bool inRepBounds = True;
// If the difference between the upper bits of the new address and the current
// address does not match the expected difference, call it outside of representable bounds.
@@ -689,7 +686,7 @@ function VnD#(CapFat) setAddress(CapFat cap, LCapAddress address, TempFields tf)
t2(False, False): return 0;
endcase;
if (diff != expectedDiff) inRepBounds = False;
if (e >= resetExp - 3) inRepBounds = True;
if (e >= resetExp - 2) inRepBounds = True;
if (!inRepBounds) ret.isCapability = False;
return VnD {v: inRepBounds, d: ret};
endfunction