Merge pull request #891 from freechipsproject/fix-l2-tlb

Fix L2 TLB

src/main/scala/rocket/BTB.scala

@@ -11,7 +11,7 @@ import freechips.rocketchip.tile.HasCoreParameters
 import freechips.rocketchip.util._
 
 case class BTBParams(
-  nEntries: Int = 32,
+  nEntries: Int = 30,
   nMatchBits: Int = 14,
   nPages: Int = 6,
   nRAS: Int = 6,
@@ -24,7 +24,6 @@ trait HasBtbParameters extends HasCoreParameters {
   val entries = btbParams.nEntries
   val updatesOutOfOrder = btbParams.updatesOutOfOrder
   val nPages = (btbParams.nPages + 1) / 2 * 2 // control logic assumes 2 divides pages
-  val opaqueBits = log2Up(entries)
 }
 
 abstract class BtbModule(implicit val p: Parameters) extends Module with HasBtbParameters
@@ -141,7 +140,7 @@ class BTBResp(implicit p: Parameters) extends BtbBundle()(p) {
   val mask = Bits(width = fetchWidth)
   val bridx = Bits(width = log2Up(fetchWidth))
   val target = UInt(width = vaddrBits)
-  val entry = UInt(width = opaqueBits)
+  val entry = UInt(width = log2Up(entries + 1))
   val bht = new BHTResp
 }
 
@@ -196,7 +195,7 @@ class BTB(implicit p: Parameters) extends BtbModule {
     if (updatesOutOfOrder) {
       val updateHits = (pageHit << 1)(Mux1H(idxMatch(r_btb_update.bits.pc), idxPages))
       (updateHits.orR, OHToUInt(updateHits))
-    } else (r_btb_update.bits.prediction.valid, r_btb_update.bits.prediction.bits.entry)
+    } else (r_btb_update.bits.prediction.valid && r_btb_update.bits.prediction.bits.entry < entries, r_btb_update.bits.prediction.bits.entry)
 
   val useUpdatePageHit = updatePageHit.orR
   val usePageHit = pageHit.orR

src/main/scala/rocket/Frontend.scala

@@ -259,6 +259,7 @@ class FrontendModule(outer: Frontend) extends LazyModuleImp(outer)
         when (taken) {
           fq.io.enq.bits.btb.valid := true
           fq.io.enq.bits.btb.bits.taken := true
+          fq.io.enq.bits.btb.bits.entry := UInt(tileParams.btb.get.nEntries)
           s2_redirect := true
         }
       }

src/main/scala/rocket/PTW.scala

@@ -136,7 +136,13 @@ class PTW(n: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreModule()(
   val l2_refill = RegNext(false.B)
   io.dpath.perf.l2miss := false
   val (l2_hit, l2_pte) = if (coreParams.nL2TLBEntries == 0) (false.B, Wire(new PTE)) else {
+    val code = new ParityCode
+    require(isPow2(coreParams.nL2TLBEntries))
+    val idxBits = log2Ceil(coreParams.nL2TLBEntries)
+    val tagBits = vpnBits - idxBits
+
     class Entry extends Bundle {
+      val tag = UInt(width = tagBits)
       val ppn = UInt(width = ppnBits)
       val d = Bool()
       val a = Bool()
@@ -144,20 +150,19 @@ class PTW(n: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreModule()(
       val x = Bool()
       val w = Bool()
       val r = Bool()
+
+      override def cloneType = new Entry().asInstanceOf[this.type]
     }
 
-    val code = new ParityCode
-    require(isPow2(coreParams.nL2TLBEntries))
-    val idxBits = log2Ceil(coreParams.nL2TLBEntries)
-    val tagBits = vpnBits - idxBits
-    val ram = SeqMem(coreParams.nL2TLBEntries, UInt(width = code.width(new Entry().getWidth + tagBits)))
+    val ram = SeqMem(coreParams.nL2TLBEntries, UInt(width = code.width(new Entry().getWidth)))
     val g = Reg(UInt(width = coreParams.nL2TLBEntries))
     val valid = RegInit(UInt(0, coreParams.nL2TLBEntries))
     val (r_tag, r_idx) = Split(r_req.addr, idxBits)
     when (l2_refill) {
       val entry = Wire(new Entry)
       entry := r_pte
-      ram.write(r_idx, code.encode(Cat(entry.asUInt, r_tag)))
+      entry.tag := r_tag
+      ram.write(r_idx, code.encode(entry.asUInt))
 
       val mask = UIntToOH(r_idx)
       valid := valid | mask
@@ -176,11 +181,11 @@ class PTW(n: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreModule()(
     val s2_rdata = code.decode(RegEnable(s1_rdata, s1_valid))
     when (s2_valid && s2_rdata.error) { valid := 0.U }
 
-    val (s2_entry, s2_tag) = Split(s2_rdata.uncorrected, tagBits)
-    val s2_hit = s2_valid && !s2_rdata.error && r_tag === s2_tag
-    io.dpath.perf.l2miss := s2_valid && !(r_tag === s2_tag)
+    val s2_entry = s2_rdata.uncorrected.asTypeOf(new Entry)
+    val s2_hit = s2_valid && !s2_rdata.error && r_tag === s2_entry.tag
+    io.dpath.perf.l2miss := s2_valid && !(r_tag === s2_entry.tag)
     val s2_pte = Wire(new PTE)
-    s2_pte := s2_entry.asTypeOf(new Entry)
+    s2_pte := s2_entry
     s2_pte.g := g(r_idx)
     s2_pte.v := true
 
@@ -261,6 +266,7 @@ class PTW(n: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreModule()(
     resp_valid(r_req_dest) := true
     resp_ae := false
     r_pte := l2_pte
+    count := pgLevels-1
   }
 }