Support superpage entries in TLB
This commit is contained in:
Andrew Waterman
@ -17,7 +17,7 @@ case object PgLevels extends Field[Int]
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case object ASIdBits extends Field[Int]
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class TLBReq(implicit p: Parameters) extends CoreBundle()(p) {
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val vpn = UInt(width = vpnBitsExtended)
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val vaddr = UInt(width = vaddrBitsExtended)
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val passthrough = Bool()
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val instruction = Bool()
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val store = Bool()
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@ -26,7 +26,7 @@ class TLBReq(implicit p: Parameters) extends CoreBundle()(p) {
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class TLBResp(implicit p: Parameters) extends CoreBundle()(p) {
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// lookup responses
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val miss = Bool(OUTPUT)
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val ppn = UInt(OUTPUT, ppnBits)
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val paddr = UInt(OUTPUT, paddrBits)
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val xcpt_ld = Bool(OUTPUT)
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val xcpt_st = Bool(OUTPUT)
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val xcpt_if = Bool(OUTPUT)
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@ -39,31 +39,33 @@ class TLB(entries: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreMod
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val resp = new TLBResp
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val ptw = new TLBPTWIO
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}
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val cacheBlockBytes = p(CacheBlockBytes)
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val camAddrBits = log2Ceil(entries)
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val camTagBits = asIdBits + vpnBits
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val valid = Reg(init = UInt(0, entries))
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val ppns = Reg(Vec(entries, UInt(width = ppnBits)))
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val tags = Reg(Vec(entries, UInt(width = asIdBits + vpnBits)))
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val totalEntries = entries + 1
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val normalEntries = entries
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val specialEntry = entries
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val valid = Reg(init = UInt(0, totalEntries))
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val ppns = Reg(Vec(totalEntries, UInt(width = ppnBits)))
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val tags = Reg(Vec(totalEntries, UInt(width = asIdBits + vpnBits)))
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val levels = Reg(Vec(totalEntries, UInt(width = log2Ceil(pgLevels))))
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val s_ready :: s_request :: s_wait :: s_wait_invalidate :: Nil = Enum(UInt(), 4)
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val state = Reg(init=s_ready)
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val r_refill_tag = Reg(UInt(width = asIdBits + vpnBits))
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val r_refill_waddr = Reg(UInt(width = log2Ceil(entries)))
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val r_refill_waddr = Reg(UInt(width = log2Ceil(normalEntries)))
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val r_req = Reg(new TLBReq)
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val do_mprv = io.ptw.status.mprv && !io.req.bits.instruction
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val priv = Mux(do_mprv, io.ptw.status.mpp, io.ptw.status.prv)
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val priv_s = priv === PRV.S
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val priv_uses_vm = priv <= PRV.S && !io.ptw.status.debug
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val vm_enabled = Bool(usingVM) && io.ptw.ptbr.mode(io.ptw.ptbr.mode.getWidth-1) && priv_uses_vm && !io.req.bits.passthrough
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// share a single physical memory attribute checker (unshare if critical path)
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val passthrough_ppn = io.req.bits.vpn(ppnBits-1, 0)
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val (vpn, pgOffset) = Split(io.req.bits.vaddr, pgIdxBits)
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val refill_ppn = io.ptw.resp.bits.pte.ppn(ppnBits-1, 0)
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val do_refill = Bool(usingVM) && io.ptw.resp.valid
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val mpu_ppn = Mux(do_refill, refill_ppn, passthrough_ppn)
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val mpu_physaddr = mpu_ppn << pgIdxBits
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val mpu_ppn = Mux(do_refill, refill_ppn,
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Mux(vm_enabled, ppns.last, vpn(ppnBits-1, 0)))
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val mpu_physaddr = Cat(mpu_ppn, io.req.bits.vaddr(pgIdxBits-1, 0))
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val legal_address = edge.manager.findSafe(mpu_physaddr).reduce(_||_)
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def fastCheck(member: TLManagerParameters => Boolean) =
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legal_address && Mux1H(edge.manager.findFast(mpu_physaddr), edge.manager.managers.map(m => Bool(member(m))))
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@ -71,65 +73,75 @@ class TLB(entries: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreMod
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val prot_w = fastCheck(_.supportsPutFull)
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val prot_x = fastCheck(_.executable)
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val cacheable = fastCheck(_.supportsAcquireB)
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val xferSizes = TransferSizes(cacheBlockBytes, cacheBlockBytes)
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val allSizes = TransferSizes(1, cacheBlockBytes)
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val amoSizes = TransferSizes(1, xLen/8)
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edge.manager.managers.foreach { m =>
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require (m.minAlignment >= 4096, s"MemoryMap region ${m.name} must be page-aligned (is ${m.minAlignment})")
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require (!m.supportsGet || m.supportsGet .contains(allSizes), s"MemoryMap region ${m.name} only supports ${m.supportsGet} Get, but must support ${allSizes}")
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require (!m.supportsPutFull || m.supportsPutFull .contains(allSizes), s"MemoryMap region ${m.name} only supports ${m.supportsPutFull} PutFull, but must support ${allSizes}")
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require (!m.supportsAcquireB || m.supportsAcquireB .contains(xferSizes), s"MemoryMap region ${m.name} only supports ${m.supportsAcquireB} AcquireB, but must support ${xferSizes}")
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require (!m.supportsAcquireT || m.supportsAcquireT .contains(xferSizes), s"MemoryMap region ${m.name} only supports ${m.supportsAcquireT} AcquireT, but must support ${xferSizes}")
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require (!m.supportsLogical || m.supportsLogical .contains(amoSizes), s"MemoryMap region ${m.name} only supports ${m.supportsLogical} Logical, but must support ${amoSizes}")
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require (!m.supportsArithmetic || m.supportsArithmetic.contains(amoSizes), s"MemoryMap region ${m.name} only supports ${m.supportsArithmetic} Arithmetic, but must support ${amoSizes}")
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require (m.supportsAcquireT || !m.supportsPutFull || !m.supportsAcquireB, s"MemoryMap region ${m.name} supports PutFull and AcquireB but not AcquireT")
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val isSpecial = {
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val homogeneous = Wire(init = false.B)
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for (i <- 0 until pgLevels) {
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println(BigInt(1) << (pgIdxBits + ((pgLevels - 1 - i) * pgLevelBits)))
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when (io.ptw.resp.bits.level === i) { homogeneous := TLBPageLookup(edge.manager.managers, xLen, p(CacheBlockBytes), BigInt(1) << (pgIdxBits + ((pgLevels - 1 - i) * pgLevelBits)))(mpu_physaddr).homogeneous }
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}
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!homogeneous
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}
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val lookup_tag = Cat(io.ptw.ptbr.asid, io.req.bits.vpn(vpnBits-1,0))
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val vm_enabled = Bool(usingVM) && io.ptw.ptbr.mode(io.ptw.ptbr.mode.getWidth-1) && priv_uses_vm && !io.req.bits.passthrough
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val hitsVec = (0 until entries).map(i => valid(i) && vm_enabled && tags(i) === lookup_tag) :+ !vm_enabled
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val lookup_tag = Cat(io.ptw.ptbr.asid, vpn(vpnBits-1,0))
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val hitsVec = (0 until totalEntries).map { i => vm_enabled && {
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var tagMatch = valid(i)
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for (j <- 0 until pgLevels) {
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val base = vpnBits - (j + 1) * pgLevelBits
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tagMatch = tagMatch && (levels(i) < j || tags(i)(base + pgLevelBits - 1, base) === vpn(base + pgLevelBits - 1, base))
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}
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tagMatch
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}} :+ !vm_enabled
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val hits = hitsVec.asUInt
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val level = Mux1H(hitsVec.init, levels)
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val partialPPN = Mux1H(hitsVec.init, ppns)
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val ppn = {
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var ppn = Mux(vm_enabled, partialPPN, vpn)(pgLevelBits*pgLevels - 1, pgLevelBits*(pgLevels - 1))
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for (i <- 1 until pgLevels)
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ppn = Cat(ppn, (Mux(level < i, vpn, 0.U) | partialPPN)(vpnBits - i*pgLevelBits - 1, vpnBits - (i + 1)*pgLevelBits))
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ppn
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}
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// permission bit arrays
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val pte_array = Reg(new PTE)
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val u_array = Reg(UInt(width = entries)) // user permission
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val sw_array = Reg(UInt(width = entries)) // write permission
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val sx_array = Reg(UInt(width = entries)) // execute permission
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val sr_array = Reg(UInt(width = entries)) // read permission
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val xr_array = Reg(UInt(width = entries)) // read permission to executable page
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val cash_array = Reg(UInt(width = entries)) // cacheable
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val u_array = Reg(UInt(width = totalEntries)) // user permission
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val sw_array = Reg(UInt(width = totalEntries)) // write permission
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val sx_array = Reg(UInt(width = totalEntries)) // execute permission
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val sr_array = Reg(UInt(width = totalEntries)) // read permission
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val xr_array = Reg(UInt(width = totalEntries)) // read permission to executable page
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val cash_array = Reg(UInt(width = normalEntries)) // cacheable
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when (do_refill) {
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val waddr = Mux(isSpecial, specialEntry.U, r_refill_waddr)
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val pte = io.ptw.resp.bits.pte
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ppns(r_refill_waddr) := pte.ppn
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tags(r_refill_waddr) := r_refill_tag
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ppns(waddr) := pte.ppn
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tags(waddr) := r_refill_tag
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levels(waddr) := io.ptw.resp.bits.level
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val mask = UIntToOH(r_refill_waddr)
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val mask = UIntToOH(waddr)
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valid := valid | mask
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u_array := Mux(pte.u, u_array | mask, u_array & ~mask)
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sw_array := Mux(pte.sw() && prot_w, sw_array | mask, sw_array & ~mask)
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sx_array := Mux(pte.sx() && prot_x, sx_array | mask, sx_array & ~mask)
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sr_array := Mux(pte.sr() && prot_r, sr_array | mask, sr_array & ~mask)
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xr_array := Mux(pte.sx() && prot_r, xr_array | mask, xr_array & ~mask)
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sw_array := Mux(pte.sw() && (isSpecial || prot_w), sw_array | mask, sw_array & ~mask)
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sx_array := Mux(pte.sx() && (isSpecial || prot_x), sx_array | mask, sx_array & ~mask)
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sr_array := Mux(pte.sr() && (isSpecial || prot_r), sr_array | mask, sr_array & ~mask)
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xr_array := Mux(pte.sx() && (isSpecial || prot_r), xr_array | mask, xr_array & ~mask)
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cash_array := Mux(cacheable, cash_array | mask, cash_array & ~mask)
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}
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val plru = new PseudoLRU(entries)
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val plru = new PseudoLRU(normalEntries)
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val repl_waddr = Mux(!valid.andR, PriorityEncoder(~valid), plru.replace)
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val priv_ok = Mux(priv_s, ~Mux(io.ptw.status.pum, u_array, UInt(0)), u_array)
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val w_array = Cat(prot_w, priv_ok & sw_array)
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val x_array = Cat(prot_x, priv_ok & sx_array)
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val r_array = Cat(prot_r | (prot_x & io.ptw.status.mxr), priv_ok & (sr_array | Mux(io.ptw.status.mxr, xr_array, UInt(0))))
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val c_array = Cat(cacheable, cash_array)
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val w_array = Cat(prot_w, priv_ok & ~(~prot_w << specialEntry) & sw_array)
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val x_array = Cat(prot_x, priv_ok & ~(~prot_x << specialEntry) & sx_array)
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val r_array = Cat(prot_r, priv_ok & ~(~prot_r << specialEntry) & (sr_array | Mux(io.ptw.status.mxr, xr_array, UInt(0))))
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val c_array = Cat(cacheable, cacheable, cash_array)
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val bad_va =
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if (vpnBits == vpnBitsExtended) Bool(false)
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else io.req.bits.vpn(vpnBits) =/= io.req.bits.vpn(vpnBits-1)
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val tlb_hit = hits(entries-1, 0).orR
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else vpn(vpnBits) =/= vpn(vpnBits-1)
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val tlb_hit = hits(totalEntries-1, 0).orR
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val tlb_miss = vm_enabled && !bad_va && !tlb_hit
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when (io.req.valid && !tlb_miss) {
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plru.access(OHToUInt(hits(entries-1, 0)))
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when (io.req.valid && !tlb_miss && !hits(specialEntry)) {
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plru.access(OHToUInt(hits(normalEntries-1, 0)))
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}
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// Superpages create the possibility that two entries in the TLB may match.
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@ -137,7 +149,7 @@ class TLB(entries: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreMod
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// we must return either the old translation or the new translation. This
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// isn't compatible with the Mux1H approach. So, flush the TLB and report
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// a miss on duplicate entries.
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val multipleHits = PopCountAtLeast(hits(entries-1, 0), 2)
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val multipleHits = PopCountAtLeast(hits(totalEntries-1, 0), 2)
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io.req.ready := state === s_ready
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io.resp.xcpt_ld := bad_va || (~r_array & hits).orR
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@ -145,7 +157,7 @@ class TLB(entries: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreMod
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io.resp.xcpt_if := bad_va || (~x_array & hits).orR
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io.resp.cacheable := (c_array & hits).orR
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io.resp.miss := do_refill || tlb_miss || multipleHits
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io.resp.ppn := Mux1H(hitsVec, ppns :+ passthrough_ppn)
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io.resp.paddr := Cat(ppn, pgOffset)
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io.ptw.req.valid := state === s_request
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io.ptw.req.bits <> io.ptw.status
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