MMU produces page fault when upper bits aren't equal. Renamed input to MMU to be 'Address' and moved translation mux into MMU out of TLB

wally-pipelined/src/ifu/ifu.sv

@@ -120,7 +120,7 @@ module ifu (
   endgenerate
 
   mmu #(.TLB_ENTRIES(`ITLB_ENTRIES), .IMMU(1))
-  immu(.VirtualAddress(PCF),
+  immu(.Address(PCF),
        .Size(2'b10),
        .PTE(PageTableEntryF),
        .PageTypeWriteVal(PageTypeF),

wally-pipelined/src/lsu/lsu.sv

@@ -115,10 +115,6 @@ module lsu
 				STATE_PTW_DONE} statetype;
   statetype CurrState, NextState;
   
-
-  logic 		       PMPInstrAccessFaultF, PMAInstrAccessFaultF; // *** these are just so that the mmu has somewhere to put these outputs since they aren't used in dmem
-  // *** if you're allowed to parameterize outputs/ inputs existence, these are an easy delete.
-
   logic 		       DTLBMissM;
   logic [`XLEN-1:0] 	       PageTableEntryM;
   logic [1:0] 		       PageTypeM;
@@ -216,7 +212,7 @@ module lsu
   
   
   mmu #(.TLB_ENTRIES(`DTLB_ENTRIES), .IMMU(0))
-  dmmu(.VirtualAddress(MemAdrMtoLSU),
+  dmmu(.Address(MemAdrMtoLSU),
        .Size(SizeToLSU[1:0]),
        .PTE(PageTableEntryM),
        .PageTypeWriteVal(PageTypeM),

wally-pipelined/src/mmu/mmu.sv

@@ -44,8 +44,8 @@ module mmu #(parameter TLB_ENTRIES = 8, // nuber of TLB Entries
   // 11 - TLB is accessed for both read and write
   input logic              DisableTranslation,
 
-  // Virtual address input
+  //  address input (could be virtual or physical)
-  input logic  [`XLEN-1:0] VirtualAddress,
+  input logic  [`XLEN-1:0] Address,
   input logic  [1:0]       Size, // 00 = 8 bits, 01 = 16 bits, 10 = 32 bits , 11 = 64 bits
 
   // Controls for writing a new entry to the TLB
@@ -75,6 +75,8 @@ module mmu #(parameter TLB_ENTRIES = 8, // nuber of TLB Entries
 
 );
 
+  logic [`PA_BITS-1:0] TLBPhysicalAddress;
+  logic [`XLEN+1:0]    AddressExt;
   logic PMPSquashBusAccess, PMASquashBusAccess;
   logic Cacheable, Idempotent, AtomicAllowed; // *** here so that the pmachecker has somewhere to put these outputs. *** I'm leaving them as outputs to pma checker, but I'm stopping them here.
   // Translation lookaside buffer
@@ -82,6 +84,7 @@ module mmu #(parameter TLB_ENTRIES = 8, // nuber of TLB Entries
   logic PMAInstrAccessFaultF, PMPInstrAccessFaultF;
   logic PMALoadAccessFaultM, PMPLoadAccessFaultM;
   logic PMAStoreAccessFaultM, PMPStoreAccessFaultM;
+  logic Translate;
 
 
   // only instantiate TLB if Virtual Memory is supported
@@ -92,14 +95,16 @@ module mmu #(parameter TLB_ENTRIES = 8, // nuber of TLB Entries
       assign WriteAccess = WriteAccessM;
       tlb #(.TLB_ENTRIES(TLB_ENTRIES), .ITLB(IMMU)) tlb(.*);
     end else begin // just pass address through as physical
-      logic [`XLEN+1:0]     VAExt;
+      assign Translate = 0;
-      assign VAExt = {2'b00, VirtualAddress}; // extend length of virtual address if necessary for RV32
-      assign PhysicalAddress = VAExt[`PA_BITS-1:0];
       assign TLBMiss = 0;
-      assign TLBHit = 1;
+      assign TLBHit = 1; // *** is this necessary
       assign TLBPageFault = 0;
      end
   endgenerate
+
+  // If translation is occuring, select translated physical address from TLB
+  assign AddressExt = {2'b00, Address}; // extend length of virtual address if necessary for RV32
+  mux2 #(`PA_BITS) addressmux(AddressExt[`PA_BITS-1:0], TLBPhysicalAddress, Translate, PhysicalAddress);
   
   ///////////////////////////////////////////
   // Check physical memory accesses

wally-pipelined/src/mmu/tlb.sv

@@ -68,8 +68,8 @@ module tlb #(parameter TLB_ENTRIES = 8,
   input logic              ReadAccess, WriteAccess,
   input logic              DisableTranslation,
 
-  // Virtual address input
+  // address input before translation (could be physical or virtual)
-  input logic  [`XLEN-1:0] VirtualAddress,
+  input logic  [`XLEN-1:0] Address,
 
   // Controls for writing a new entry to the TLB
   input logic  [`XLEN-1:0] PTE,
@@ -80,16 +80,15 @@ module tlb #(parameter TLB_ENTRIES = 8,
   input logic              TLBFlush,
 
   // Physical address outputs
-  output logic [`PA_BITS-1:0] PhysicalAddress,
+  output logic [`PA_BITS-1:0] TLBPhysicalAddress,
   output logic             TLBMiss,
   output logic             TLBHit,
+  output logic             Translate,
 
   // Faults
   output logic             TLBPageFault
 );
 
-  logic Translate;
-
   // Store current virtual memory mode (SV32, SV39, SV48, ect...)
   //logic [`SVMODE_BITS-1:0] SvMode;
   logic  [1:0]       EffectivePrivilegeMode; // privilege mode, possibly modified by MPRV
@@ -99,8 +98,7 @@ module tlb #(parameter TLB_ENTRIES = 8,
   // Sections of the virtual and physical addresses
   logic [`VPN_BITS-1:0] VirtualPageNumber;
   logic [`PPN_BITS-1:0] PhysicalPageNumber, PhysicalPageNumberMixed;
-  logic [`PA_BITS-1:0]  PhysicalAddressFull;
+  logic [`XLEN+1:0]     AddressExt;
-  logic [`XLEN+1:0]     VAExt;
 
   // Sections of the page table entry
   logic [7:0]           PTEAccessBits;
@@ -116,7 +114,7 @@ module tlb #(parameter TLB_ENTRIES = 8,
   assign ASID = SATP_REGW[`ASID_BASE+`ASID_BITS-1:`ASID_BASE];
 
   // Determine whether to write TLB
-  assign VirtualPageNumber = VirtualAddress[`VPN_BITS+11:12];
+  assign VirtualPageNumber = Address[`VPN_BITS+11:12];
 
   tlbcontrol tlbcontrol(.*);
 
@@ -134,7 +132,5 @@ module tlb #(parameter TLB_ENTRIES = 8,
 
   // Output the hit physical address if translation is currently on.
   // Provide physical address of zero if not TLBHits, to cause segmentation error if miss somehow percolated through signal
-  assign VAExt = {2'b00, VirtualAddress}; // extend length of virtual address if necessary for RV32
+  mux2 #(`PA_BITS) hitmux('0, {PhysicalPageNumberMixed, Address[11:0]}, TLBHit, TLBPhysicalAddress); // set PA to 0 if TLB misses, to cause segementation error if this miss somehow passes through system
-  mux2 #(`PA_BITS) hitmux('0, {PhysicalPageNumberMixed, VirtualAddress[11:0]}, TLBHit, PhysicalAddressFull); // set PA to 0 if TLB misses, to cause segementation error if this miss somehow passes through system
-  mux2 #(`PA_BITS) addressmux(VAExt[`PA_BITS-1:0], PhysicalAddressFull, Translate, PhysicalAddress);
 endmodule

wally-pipelined/src/mmu/tlbcontrol.sv

@@ -32,6 +32,7 @@ module tlbcontrol #(parameter TLB_ENTRIES = 8,
 
   // Current value of satp CSR (from privileged unit)
   input logic  [`XLEN-1:0] SATP_REGW,
+  input logic  [`XLEN-1:0] Address,
   input logic              STATUS_MXR, STATUS_SUM, STATUS_MPRV,
   input logic  [1:0]       STATUS_MPP,
   input logic  [1:0]       PrivilegeModeW, // Current privilege level of the processeor
@@ -58,7 +59,8 @@ module tlbcontrol #(parameter TLB_ENTRIES = 8,
   logic [`SVMODE_BITS-1:0] SVMode;
 
   logic PTE_D, PTE_A, PTE_U, PTE_X, PTE_W, PTE_R; // Useful PTE Control Bits
-  logic                  DAFault;
+  logic                  UpperBitsUnequalPageFault;
+  logic                  DAPageFault;
   logic                  TLBAccess;
 
   // Grab the sv mode from SATP and determine whether translation should occur
@@ -66,13 +68,27 @@ module tlbcontrol #(parameter TLB_ENTRIES = 8,
   assign EffectivePrivilegeMode = (ITLB == 1) ? PrivilegeModeW : (STATUS_MPRV ? STATUS_MPP : PrivilegeModeW); // DTLB uses MPP mode when MPRV is 1
   assign Translate = (SVMode != `NO_TRANSLATE) & (EffectivePrivilegeMode != `M_MODE) & ~ DisableTranslation; 
   generate
-      if (`XLEN==64) assign SV39Mode = (SVMode == `SV39);
+      if (`XLEN==64) begin
-      else           assign SV39Mode = 0;
+          assign SV39Mode = (SVMode == `SV39);
+          // generate page fault if upper bits aren't all the same
+          logic UpperOnes39, UpperZeros39, UpperOnes48, UpperZeros48;
+          assign UpperOnes39 = &(Address[63:39]);
+          assign UpperZeros39 = ~|(Address[63:39]);
+          assign UpperOnes48 = &(Address[63:48]);
+          assign UpperZeros48 = ~|(Address[63:48]);
+          assign UpperBitsUnequalPageFault = SV39Mode ? (Address[38] ? UpperOnes39 : UpperZeros39) : (Address[47] ? UpperOnes48 : UpperZeros48);
+      end else begin
+          assign SV39Mode = 0;
+          assign UpperBitsUnequalPageFault = 0;
+      end           
   endgenerate
 
   // Determine whether TLB is being used
   assign TLBAccess = ReadAccess || WriteAccess;
 
+  // Check whether upper bits of virtual addresss are all equal
+
+
   // unswizzle useful PTE bits
   assign {PTE_D, PTE_A} = PTEAccessBits[7:6];
   assign {PTE_U, PTE_X, PTE_W, PTE_R} = PTEAccessBits[4:1];
@@ -87,8 +103,8 @@ module tlbcontrol #(parameter TLB_ENTRIES = 8,
       assign ImproperPrivilege = ((EffectivePrivilegeMode == `U_MODE) && ~PTE_U) ||
         ((EffectivePrivilegeMode == `S_MODE) && PTE_U);
       // fault for software handling if access bit is off
-      assign DAFault = ~PTE_A;
+      assign DAPageFault = ~PTE_A;
-      assign TLBPageFault = Translate && TLBHit && (ImproperPrivilege || ~PTE_X || DAFault);
+      assign TLBPageFault = Translate && TLBHit && (ImproperPrivilege || ~PTE_X || DAPageFault || UpperBitsUnequalPageFault);
     end else begin
       logic ImproperPrivilege, InvalidRead, InvalidWrite;
 
@@ -104,8 +120,8 @@ module tlbcontrol #(parameter TLB_ENTRIES = 8,
       // low.
       assign InvalidWrite = WriteAccess && ~PTE_W;
       // Fault for software handling if access bit is off or writing a page with dirty bit off
-      assign DAFault = ~PTE_A | WriteAccess & ~PTE_D; 
+      assign DAPageFault = ~PTE_A | WriteAccess & ~PTE_D; 
-      assign TLBPageFault = Translate && TLBHit && (ImproperPrivilege || InvalidRead || InvalidWrite || DAFault);
+      assign TLBPageFault = Translate && TLBHit && (ImproperPrivilege || InvalidRead || InvalidWrite || DAPageFault || UpperBitsUnequalPageFault);
     end
   endgenerate
 

wally-pipelined/src/privileged/csrsr.sv

@@ -125,7 +125,8 @@ module csrsr (
       STATUS_SIE <= #1 0; //`S_SUPPORTED;
       STATUS_UIE <= #1 0; //`U_SUPPORTED;
     end else if (~StallW) begin
-      if (FloatRegWriteW) STATUS_FS_INT <= #12'b11; // mark Float State dirty  *** this should happen in M stage, be part of if/else
+      if (FloatRegWriteW) STATUS_FS_INT <= #12'b11; // mark Float State dirty  *** this should happen in M stage, be part of if/else;
+          // *** also, FS_INT needs to be set when any bits of the fcsr are written
       if (TrapM) begin
         // Update interrupt enables per Privileged Spec p. 21
         // y = PrivilegeModeW