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Put page homogeneity checker in PMP

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Avoids redundancy between ITLB and DTLB
This commit is contained in:
Andrew Waterman
2017-03-21 12:01:32 -07:00
parent 9e05200e51
commit d3bda9574c
3 changed files with 47 additions and 43 deletions
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60
src/main/scala/rocket/PMP.scala
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@@ -56,22 +56,23 @@ class PMP(implicit p: Parameters) extends PMPReg {
}
}
private def decomposedBoundMatch(xHi: UInt, xLo: UInt, lsbMask: UInt, lgMaxSize: Int) = {
val msbsLess = xHi < (comparand >> lgMaxSize)
val msbsEqual = (xHi ^ (comparand >> lgMaxSize)) === 0
val lsbsLess = xLo < (comparand(lgMaxSize-1, 0) & lsbMask(lgMaxSize-1, 0))
msbsLess || (msbsEqual && lsbsLess)
private def boundMatch(x: UInt, lsbMask: UInt, lgMaxSize: Int) = {
if (lgMaxSize <= lgAlign) {
x < comparand
} else {
// break up the circuit; the MSB part will be CSE'd
val msbsLess = (x >> lgMaxSize) < (comparand >> lgMaxSize)
val msbsEqual = ((x >> lgMaxSize) ^ (comparand >> lgMaxSize)) === 0
val lsbsLess = (x(lgMaxSize-1, 0) | lsbMask) < comparand(lgMaxSize-1, 0)
msbsLess || (msbsEqual && lsbsLess)
}
}
private def boundMatch(x: UInt, lsbMask: UInt, lgMaxSize: Int) =
if (lgMaxSize <= lgAlign) x < comparand
else decomposedBoundMatch(x >> lgMaxSize, x(lgMaxSize-1, 0), lsbMask, lgMaxSize)
private def lowerBoundMatch(x: UInt, lgSize: UInt, lgMaxSize: Int) =
!boundMatch(x, ((BigInt(1) << lgMaxSize) - 1).U << lgSize, lgMaxSize)
!boundMatch(x, ~(((BigInt(1) << lgMaxSize) - 1).U << lgSize)(lgMaxSize-1, 0), lgMaxSize)
private def upperBoundMatch(x: UInt, lgMaxSize: Int) =
boundMatch(x, ((BigInt(1) << lgMaxSize) - 1).U, lgMaxSize)
boundMatch(x, 0.U, lgMaxSize)
private def rangeMatch(x: UInt, lgSize: UInt, lgMaxSize: Int, prev: PMP) =
prev.lowerBoundMatch(x, lgSize, lgMaxSize) && upperBoundMatch(x, lgMaxSize)
@@ -85,26 +86,25 @@ class PMP(implicit p: Parameters) extends PMPReg {
f(pgIdxBits + (pgLevels - 1 - i) * pgLevelBits)
}
private def rangeHomogeneous(x: UInt, pgLevel: UInt, lgMaxSize: Int, prev: PMP) = {
val beginsAfterLower = !prev.boundMatch(x, ((BigInt(1) << lgMaxSize) - 1).U, lgMaxSize) // CSE with rangeMatch
val beginsAfterUpper = !boundMatch(x, ((BigInt(1) << lgMaxSize) - 1).U, lgMaxSize) // CSE with rangeMatch
private def rangeHomogeneous(x: UInt, pgLevel: UInt, prev: PMP) = {
val beginsAfterLower = !(x < prev.comparand)
val beginsAfterUpper = !(x < comparand)
val endsBeforeLower = pgLevelMap { idxBits => (x >> idxBits) < (prev.comparand << idxBits) } (pgLevel)
val endsBeforeUpper = pgLevelMap { idxBits => (x >> idxBits) > (comparand << idxBits) } (pgLevel)
val endsBeforeUpper = pgLevelMap { idxBits => (x >> idxBits) < (comparand << idxBits) } (pgLevel)
endsBeforeLower || beginsAfterUpper || (beginsAfterLower && endsBeforeUpper)
}
// returns whether this PMP completely contains, or contains none of, a page
def homogeneous(x: UInt, pgLevel: UInt, lgMaxSize: Int, prev: PMP): Bool =
!cfg.p(0) || Mux(cfg.a(1), rangeHomogeneous(x, pgLevel, lgMaxSize, prev), pow2Homogeneous(x, pgLevel))
def homogeneous(x: UInt, pgLevel: UInt, prev: PMP): Bool =
!cfg.p(0) || Mux(cfg.a(1), rangeHomogeneous(x, pgLevel, prev), pow2Homogeneous(x, pgLevel))
// returns whether this matching PMP fully contains the access
def aligned(x: UInt, lgSize: UInt, lgMaxSize: Int, prev: PMP): Bool = if (lgMaxSize <= lgAlign) true.B else {
val lsbMask = ((BigInt(1) << lgMaxSize) - 1).U << lgSize
val alignMask = ~lsbMask(lgMaxSize-1, 0)
val lowerBoundOK = !prev.upperBoundMatch(x, lgMaxSize)
val upperBoundOK = decomposedBoundMatch(x >> lgMaxSize, x(lgMaxSize-1, 0) | alignMask, lsbMask, lgMaxSize)
val rangeAligned = lowerBoundOK && upperBoundOK
val pow2Aligned = (alignMask & ~mask(lgMaxSize-1, 0)) === 0
val lsbMask = ~(((BigInt(1) << lgMaxSize) - 1).U << lgSize)(lgMaxSize-1, 0)
val straddlesLowerBound = ((x >> lgMaxSize) ^ (prev.comparand >> lgMaxSize)) === 0 && (prev.comparand(lgMaxSize-1, 0) & ~x(lgMaxSize-1, 0)) =/= 0
val straddlesUpperBound = ((x >> lgMaxSize) ^ (comparand >> lgMaxSize)) === 0 && (comparand(lgMaxSize-1, 0) & (x(lgMaxSize-1, 0) | lsbMask)) =/= 0
val rangeAligned = !(straddlesLowerBound || straddlesUpperBound)
val pow2Aligned = (lsbMask & ~mask(lgMaxSize-1, 0)) === 0
Mux(cfg.a(1), rangeAligned, pow2Aligned)
}
@@ -113,6 +113,14 @@ class PMP(implicit p: Parameters) extends PMPReg {
cfg.p(0) && Mux(cfg.a(1), rangeMatch(x, lgSize, lgMaxSize, prev), pow2Match(x, lgSize, lgMaxSize))
}
class PMPHomogeneityChecker(pmps: Seq[PMP])(implicit p: Parameters) {
def apply(addr: UInt, pgLevel: UInt): Bool = {
((true.B, 0.U.asTypeOf(new PMP)) /: pmps) { case ((h, prev), pmp) =>
(h && pmp.homogeneous(addr, pgLevel, prev), pmp)
}._1
}
}
class PMPChecker(lgMaxSize: Int)(implicit p: Parameters) extends CoreModule()(p)
with HasRocketCoreParameters {
val io = new Bundle {
@@ -123,8 +131,6 @@ class PMPChecker(lgMaxSize: Int)(implicit p: Parameters) extends CoreModule()(p)
val r = Bool(OUTPUT)
val w = Bool(OUTPUT)
val x = Bool(OUTPUT)
val pgLevel = UInt(INPUT, log2Ceil(pgLevels))
val homogeneous = Bool(OUTPUT)
}
val default = io.prv > PRV.S
@@ -133,10 +139,6 @@ class PMPChecker(lgMaxSize: Int)(implicit p: Parameters) extends CoreModule()(p)
pmp0.cfg.w := default
pmp0.cfg.x := default
io.homogeneous := ((true.B, pmp0) /: io.pmp) { case ((h, prev), pmp) =>
(h && pmp.homogeneous(io.addr, io.pgLevel, lgMaxSize, prev), pmp)
}._1
val res = (pmp0 /: (io.pmp zip (pmp0 +: io.pmp)).reverse) { case (prev, (pmp, prevPMP)) =>
val hit = pmp.hit(io.addr, io.size, lgMaxSize, prevPMP)
val ignore = default && !pmp.cfg.m