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Set PRV=M when entering debug mode 

Debug mode mostly behaves like M-mode, so this approach avoids having
to check the debug bit in most permission checks.
This commit is contained in:
Andrew Waterman 2017-03-14 14:37:09 -07:00
parent cf168e419b
commit b1b405404d
2 changed files with 8 additions and 8 deletions
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14
src/main/scala/rocket/CSR.scala
View File

@ -231,7 +231,6 @@ class CSRFile(perfEventSets: EventSets = new EventSets(Seq()))(implicit p: Param
Causes.user_ecall).map(1 << _).sum)
val reg_debug = Reg(init=Bool(false))
val effective_prv = Cat(reg_debug, reg_mstatus.prv)
val reg_dpc = Reg(UInt(width = vaddrBitsExtended))
val reg_dscratch = Reg(UInt(width = xLen))
val reg_singleStepped = Reg(Bool())
@ -415,20 +414,20 @@ class CSRFile(perfEventSets: EventSets = new EventSets(Seq()))(implicit p: Param
val insn_wfi = system_insn && opcode(5)
private def decodeAny(m: LinkedHashMap[Int,Bits]): Bool = m.map { case(k: Int, _: Bits) => io.decode.csr === k }.reduce(_||_)
val allow_wfi = Bool(!usingVM) || effective_prv > PRV.S || !reg_mstatus.tw
val allow_sfence_vma = Bool(!usingVM) || effective_prv > PRV.S || !reg_mstatus.tvm
val allow_sret = Bool(!usingVM) || effective_prv > PRV.S || !reg_mstatus.tsr
val allow_wfi = Bool(!usingVM) || reg_mstatus.prv > PRV.S || !reg_mstatus.tw
val allow_sfence_vma = Bool(!usingVM) || reg_mstatus.prv > PRV.S || !reg_mstatus.tvm
val allow_sret = Bool(!usingVM) || reg_mstatus.prv > PRV.S || !reg_mstatus.tsr
io.decode.fp_illegal := io.status.fs === 0 || !reg_misa('f'-'a')
io.decode.rocc_illegal := io.status.xs === 0 || !reg_misa('x'-'a')
io.decode.read_illegal := effective_prv < io.decode.csr(9,8) ||
io.decode.read_illegal := reg_mstatus.prv < io.decode.csr(9,8) ||
!decodeAny(read_mapping) ||
io.decode.csr === CSRs.sptbr && !allow_sfence_vma ||
(io.decode.csr.inRange(CSR.firstCtr, CSR.firstCtr + CSR.nCtr) || io.decode.csr.inRange(CSR.firstCtrH, CSR.firstCtrH + CSR.nCtr)) && effective_prv <= PRV.S && hpm_mask(io.decode.csr(log2Ceil(CSR.firstCtr)-1,0)) ||
(io.decode.csr.inRange(CSR.firstCtr, CSR.firstCtr + CSR.nCtr) || io.decode.csr.inRange(CSR.firstCtrH, CSR.firstCtrH + CSR.nCtr)) && reg_mstatus.prv <= PRV.S && hpm_mask(io.decode.csr(log2Ceil(CSR.firstCtr)-1,0)) ||
Bool(usingDebug) && decodeAny(debug_csrs) && !reg_debug ||
Bool(usingFPU) && decodeAny(fp_csrs) && io.decode.fp_illegal
io.decode.write_illegal := io.decode.csr(11,10).andR
io.decode.write_flush := !(io.decode.csr >= CSRs.mscratch && io.decode.csr <= CSRs.mbadaddr || io.decode.csr >= CSRs.sscratch && io.decode.csr <= CSRs.sbadaddr)
io.decode.system_illegal := effective_prv < io.decode.csr(9,8) ||
io.decode.system_illegal := reg_mstatus.prv < io.decode.csr(9,8) ||
!io.decode.csr(5) && io.decode.csr(2) && !allow_wfi ||
!io.decode.csr(5) && io.decode.csr(1) && !allow_sret ||
io.decode.csr(5) && !allow_sfence_vma
@ -482,6 +481,7 @@ class CSRFile(perfEventSets: EventSets = new EventSets(Seq()))(implicit p: Param
reg_dpc := epc
reg_dcsr.cause := Mux(reg_singleStepped, 4, Mux(causeIsDebugInt, 3, Mux[UInt](causeIsDebugTrigger, 2, 1)))
reg_dcsr.prv := trimPrivilege(reg_mstatus.prv)
new_prv := PRV.M
}.elsewhen (delegate) {
reg_sepc := formEPC(epc)
reg_scause := cause

2
src/main/scala/rocket/TLB.scala
View File

@ -63,7 +63,7 @@ class TLB(entries: Int)(implicit edge: TLEdgeOut, p: Parameters) extends CoreMod
val do_mprv = io.ptw.status.mprv && !io.req.bits.instruction
val priv = Mux(do_mprv, io.ptw.status.mpp, io.ptw.status.prv)
val priv_s = priv === PRV.S
val priv_uses_vm = priv <= PRV.S && !io.ptw.status.debug
val priv_uses_vm = priv <= PRV.S
val vm_enabled = Bool(usingVM) && io.ptw.ptbr.mode(io.ptw.ptbr.mode.getWidth-1) && priv_uses_vm && !io.req.bits.passthrough
// share a single physical memory attribute checker (unshare if critical path)