xref: /XiangShan/src/main/scala/xiangshan/backend/fu/NewCSR/CSRPermitModule.scala (revision b50a88ec4b3215ee22819c5f5cb3ba82f401d37f) 
1package xiangshan.backend.fu.NewCSR
2
3import chisel3._
4import chisel3.util._
5import chisel3.util.experimental.decode.TruthTable
6import xiangshan.backend.fu.NewCSR.CSRBundles.{Counteren, PrivState}
7import freechips.rocketchip.rocket.CSRs
8
9class CSRPermitModule extends Module {
10  val io = IO(new CSRPermitIO)
11
12  private val (ren, wen, addr, privState, debugMode) = (
13    io.in.csrAccess.ren,
14    io.in.csrAccess.wen,
15    io.in.csrAccess.addr,
16    io.in.privState,
17    io.in.debugMode
18  )
19
20  private val csrAccess = WireInit(ren || wen)
21
22  private val (mret, sret) = (
23    io.in.mret,
24    io.in.sret,
25  )
26
27  private val (tsr, vtsr) = (
28    io.in.status.tsr,
29    io.in.status.vtsr,
30  )
31
32  private val (tw, vtw) = (
33    io.in.status.tw,
34    io.in.status.vtw
35  )
36
37  private val (tvm, vtvm) = (
38    io.in.status.tvm,
39    io.in.status.vtvm,
40  )
41
42  private val csrIsCustom = io.in.csrIsCustom
43
44  private val (mcounteren, hcounteren, scounteren) = (
45    io.in.status.mcounteren,
46    io.in.status.hcounteren,
47    io.in.status.scounteren,
48  )
49
50  private val (mcounterenTM, hcounterenTM) = (
51    mcounteren(1),
52    hcounteren(1),
53  )
54
55  private val (menvcfg, henvcfg) = (
56    io.in.status.menvcfg,
57    io.in.status.henvcfg,
58  )
59
60  private val (menvcfgSTCE, henvcfgSTCE) = (
61    menvcfg(63),
62    henvcfg(63),
63  )
64
65  private val csrIsRO = addr(11, 10) === "b11".U
66  private val csrIsUnpriv = addr(9, 8) === "b00".U
67  private val csrIsHPM = addr >= CSRs.cycle.U && addr <= CSRs.hpmcounter31.U
68  private val counterAddr = addr(4, 0) // 32 counters
69
70  private val accessTable = TruthTable(Seq(
71    //       V PRVM ADDR
72    BitPat("b0__00___00") -> BitPat.Y(), // HU access U
73    BitPat("b1__00___00") -> BitPat.Y(), // VU access U
74    BitPat("b0__01___00") -> BitPat.Y(), // HS access U
75    BitPat("b0__01___01") -> BitPat.Y(), // HS access S
76    BitPat("b1__01___00") -> BitPat.Y(), // VS access U
77    BitPat("b1__01___01") -> BitPat.Y(), // VS access S
78    BitPat("b0__11___00") -> BitPat.Y(), // M  access HU
79    BitPat("b0__11___01") -> BitPat.Y(), // M  access HS
80    BitPat("b0__11___10") -> BitPat.Y(), // M  access H
81    BitPat("b0__11___11") -> BitPat.Y(), // M  access M
82  ), BitPat.N())
83
84  private val isDebugReg   = addr(11, 4) === "h7b".U
85  private val isTriggerReg = addr(11, 4) === "h7a".U
86
87  private val regularPrivilegeLegal = chisel3.util.experimental.decode.decoder(
88    privState.V.asUInt ## privState.PRVM.asUInt ## addr(9, 8),
89    accessTable
90  ).asBool
91
92  private val privilegeLegal = MuxCase(
93    regularPrivilegeLegal,
94    Seq(
95      isDebugReg   -> debugMode,
96      isTriggerReg -> (debugMode || privState.isModeM),
97    )
98  )
99
100  private val rwIllegal = csrIsRO && wen
101
102  private val csrAccessIllegal = (!privilegeLegal || rwIllegal)
103
104  private val mretIllegal = !privState.isModeM
105
106  private val sretIllegal = sret && (
107    privState.isModeHS && tsr || privState.isModeVS && vtsr || privState.isModeHUorVU
108  )
109
110  private val rwSatp_EX_II = csrAccess && privState.isModeHS &&  tvm && (addr === CSRs.satp.U || addr === CSRs.hgatp.U)
111  private val rwSatp_EX_VI = csrAccess && privState.isModeVS && vtvm && (addr === CSRs.satp.U)
112
113  private val rwCustom_EX_II = csrAccess && privState.isModeVS && csrIsCustom
114
115  private val accessHPM = ren && csrIsHPM
116  private val accessHPM_EX_II = accessHPM && (
117    !privState.isModeM && !mcounteren(counterAddr) ||
118    privState.isModeHU && !scounteren(counterAddr)
119  )
120  private val accessHPM_EX_VI = accessHPM && mcounteren(counterAddr) && (
121    privState.isModeVS && !hcounteren(counterAddr) ||
122    privState.isModeVU && (!hcounteren(counterAddr) || !scounteren(counterAddr))
123  )
124
125  private val rwStimecmp_EX_II = csrAccess && ((privState.isModeHS && !mcounterenTM || !privState.isModeM && !menvcfgSTCE) && addr === CSRs.vstimecmp.U ||
126    ((privState.isModeHS || privState.isModeVS) && !mcounterenTM || !privState.isModeM && !menvcfgSTCE) && addr === CSRs.stimecmp.U)
127  private val rwStimecmp_EX_VI = csrAccess && privState.isModeVS && (mcounterenTM && !hcounterenTM || menvcfgSTCE && !henvcfgSTCE) && addr === CSRs.stimecmp.U
128
129  io.out.illegal := csrAccess && csrAccessIllegal || mret && mretIllegal || sret && sretIllegal
130
131  // Todo: check correct
132  io.out.EX_II := io.out.illegal && !privState.isVirtual || rwSatp_EX_II || accessHPM_EX_II || rwStimecmp_EX_II || rwCustom_EX_II
133  io.out.EX_VI := io.out.illegal &&  privState.isVirtual || rwSatp_EX_VI || accessHPM_EX_VI || rwStimecmp_EX_VI
134
135  io.out.hasLegalWen := io.in.csrAccess.wen && !csrAccessIllegal
136  io.out.hasLegalMret := mret && !mretIllegal
137  io.out.hasLegalSret := sret && !sretIllegal
138
139  dontTouch(regularPrivilegeLegal)
140}
141
142class CSRPermitIO extends Bundle {
143  val in = Input(new Bundle {
144    val csrAccess = new Bundle {
145      val ren = Bool()
146      val wen = Bool()
147      val addr = UInt(12.W)
148    }
149    val privState = new PrivState
150    val debugMode = Bool()
151    val mret = Bool()
152    val sret = Bool()
153    val csrIsCustom = Bool()
154    val status = new Bundle {
155      // Trap SRET
156      val tsr = Bool()
157      // Virtual Trap SRET
158      val vtsr = Bool()
159      // Timeout Wait
160      val tw = Bool()
161      // Virtual Timeout Wait
162      val vtw = Bool()
163      // Trap Virtual Memory
164      val tvm = Bool()
165      // Virtual Trap Virtual Memory
166      val vtvm = Bool()
167      // Machine level counter enable, access PMC from the level less than M will trap EX_II
168      val mcounteren = UInt(32.W)
169      // Hypervisor level counter enable.
170      // Accessing PMC from VS/VU level will trap EX_VI, if m[x]=1 && h[x]=0
171      val hcounteren = UInt(32.W)
172      // Supervisor level counter enable.
173      // Accessing PMC from **HU level** will trap EX_II, if s[x]=0
174      // Accessing PMC from **VU level** will trap EX_VI, if m[x]=1 && h[x]=1 && s[x]=0
175      val scounteren = UInt(32.W)
176      // Machine environment configuration register.
177      // Accessing stimecmp or vstimecmp from **Non-M level** will trap EX_II, if menvcfg.STCE=0
178      val menvcfg = UInt(64.W)
179      // Hypervisor environment configuration register.
180      // Accessing vstimecmp from ** V level** will trap EX_VI, if menvcfg.STCE=1 && henvcfg.STCE=0
181      val henvcfg = UInt(64.W)
182    }
183  })
184
185  val out = Output(new Bundle {
186    val hasLegalWen = Bool()
187    val hasLegalMret = Bool()
188    val hasLegalSret = Bool()
189    // Todo: split illegal into EX_II and EX_VI
190    val illegal = Bool()
191    val EX_II = Bool()
192    val EX_VI = Bool()
193  })
194}
195