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more cleaning up FSM

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This commit is contained in:
David Harris 2021-07-17 04:35:51 -04:00
parent 6d8a6eeba0
commit bd270acdb6
1 changed files with 36 additions and 123 deletions
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159
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -207,10 +207,6 @@ module pagetablewalker
end
// generate
if (`XLEN == 32) begin
// *** make sure 32/34 bit addresses are being handled properly
//logic [9:0] VPN1, VPN0;
//assign VPN1 = TranslationVAdr[31:22];
//assign VPN0 = TranslationVAdr[21:12];
// A megapage is a Level 1 leaf page. This page must have zero PPN[0].
assign MegapageMisaligned = |(CurrentPPN[9:0]);
@ -317,130 +313,57 @@ module pagetablewalker
case (WalkerState)
IDLE: if (AnyTLBMissM) NextWalkerState = (SvMode == `SV48) ? LEVEL3_SET_ADRE : LEVEL2_SET_ADRE;
else NextWalkerState = IDLE;
LEVEL3_SET_ADRE: begin
NextWalkerState = LEVEL3_WDV;
//TranslationPAdr = {BasePageTablePPN, VPN3, 3'b000};
end
LEVEL3_SET_ADRE: NextWalkerState = LEVEL3_WDV;
LEVEL3_WDV: begin
//TranslationPAdr = {BasePageTablePPN, VPN3, 3'b000};
HPTWRead = 1'b1;
if (HPTWStall) begin
NextWalkerState = LEVEL3_WDV;
end else begin
NextWalkerState = LEVEL3;
PRegEn = 1'b1;
if (HPTWStall) NextWalkerState = LEVEL3_WDV;
else begin
NextWalkerState = LEVEL3;
PRegEn = 1'b1;
end
end
LEVEL3: begin
if (ValidPTE && LeafPTE && ~(TerapageMisaligned || ADPageFault)) begin
NextWalkerState = LEAF;
//TranslationPAdr = TranslationVAdr[`PA_BITS-1:0];
end
else if (ValidPTE && ~LeafPTE) begin
NextWalkerState = LEVEL2_SET_ADRE;
//TranslationPAdr = {(SvMode == `SV48) ? CurrentPPN : BasePageTablePPN, VPN2, 3'b000};
end else begin
NextWalkerState = FAULT;
end
end
LEVEL2_SET_ADRE: begin
NextWalkerState = LEVEL2_WDV;
//TranslationPAdr = {(SvMode == `SV48) ? CurrentPPN : BasePageTablePPN, VPN2, 3'b000};
end
LEVEL3:
if (ValidPTE && LeafPTE && ~(TerapageMisaligned || ADPageFault)) NextWalkerState = LEAF;
else if (ValidPTE && ~LeafPTE) NextWalkerState = LEVEL2_SET_ADRE;
else NextWalkerState = FAULT;
LEVEL2_SET_ADRE: NextWalkerState = LEVEL2_WDV;
LEVEL2_WDV: begin
//TranslationPAdr = {(SvMode == `SV48) ? CurrentPPN : BasePageTablePPN, VPN2, 3'b000};
HPTWRead = 1'b1;
if (HPTWStall) begin
NextWalkerState = LEVEL2_WDV;
end else begin
NextWalkerState = LEVEL2;
PRegEn = 1'b1;
if (HPTWStall) NextWalkerState = LEVEL2_WDV;
else begin
NextWalkerState = LEVEL2;
PRegEn = 1'b1;
end
end
LEVEL2: begin
// *** <FUTURE WORK> According to the architecture, we should
// fault upon finding a superpage that is misaligned or has 0
// access bit. The following commented line of code is
// supposed to perform that check. However, it is untested.
if (ValidPTE && LeafPTE && ~(GigapageMisaligned || ADPageFault)) begin
NextWalkerState = LEAF;
//TranslationPAdr = TranslationVAdr[`PA_BITS-1:0];
end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
else if (ValidPTE && ~LeafPTE) begin
NextWalkerState = LEVEL1_SET_ADRE;
//TranslationPAdr = {CurrentPPN, VPN1, 3'b000};
end else begin
NextWalkerState = FAULT;
end
end
LEVEL1_SET_ADRE: begin
NextWalkerState = LEVEL1_WDV;
//TranslationPAdr = {CurrentPPN, VPN1, 3'b000};
end
LEVEL2:
if (ValidPTE && LeafPTE && ~(GigapageMisaligned || ADPageFault)) NextWalkerState = LEAF;
else if (ValidPTE && ~LeafPTE) NextWalkerState = LEVEL1_SET_ADRE;
else NextWalkerState = FAULT;
LEVEL1_SET_ADRE: NextWalkerState = LEVEL1_WDV;
LEVEL1_WDV: begin
//TranslationPAdr = {CurrentPPN, VPN1, 3'b000};
HPTWRead = 1'b1;
if (HPTWStall) begin
NextWalkerState = LEVEL1_WDV;
end else begin
NextWalkerState = LEVEL1;
PRegEn = 1'b1;
if (HPTWStall) NextWalkerState = LEVEL1_WDV;
else begin
NextWalkerState = LEVEL1;
PRegEn = 1'b1;
end
end
LEVEL1: begin
// *** <FUTURE WORK> According to the architecture, we should
// fault upon finding a superpage that is misaligned or has 0
// access bit. The following commented line of code is
// supposed to perform that check. However, it is untested.
if (ValidPTE && LeafPTE && ~(MegapageMisaligned || ADPageFault)) begin
NextWalkerState = LEAF;
//TranslationPAdr = TranslationVAdr[`PA_BITS-1:0];
end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
else if (ValidPTE && ~LeafPTE) begin
NextWalkerState = LEVEL0_SET_ADRE;
//TranslationPAdr = {CurrentPPN, VPN0, 3'b000};
end else begin
NextWalkerState = FAULT;
end
end
LEVEL0_SET_ADRE: begin
NextWalkerState = LEVEL0_WDV;
//TranslationPAdr = {CurrentPPN, VPN0, 3'b000};
end
LEVEL1:
if (ValidPTE && LeafPTE && ~(MegapageMisaligned || ADPageFault)) NextWalkerState = LEAF;
else if (ValidPTE && ~LeafPTE) NextWalkerState = LEVEL0_SET_ADRE;
else NextWalkerState = FAULT;
LEVEL0_SET_ADRE: NextWalkerState = LEVEL0_WDV;
LEVEL0_WDV: begin
//TranslationPAdr = {CurrentPPN, VPN0, 3'b000};
HPTWRead = 1'b1;
if (HPTWStall) begin
NextWalkerState = LEVEL0_WDV;
end else begin
NextWalkerState = LEVEL0;
PRegEn = 1'b1;
if (HPTWStall) NextWalkerState = LEVEL0_WDV;
else begin
NextWalkerState = LEVEL0;
PRegEn = 1'b1;
end
end
LEVEL0: begin
if (ValidPTE && LeafPTE && ~ADPageFault) begin
NextWalkerState = LEAF;
//TranslationPAdr = TranslationVAdr[`PA_BITS-1:0];
end else begin
NextWalkerState = FAULT;
end
end
LEVEL0:
if (ValidPTE && LeafPTE && ~ADPageFault) NextWalkerState = LEAF;
else NextWalkerState = FAULT;
LEAF: begin
PageTableEntry = CurrentPTE;
PageType = (PreviousWalkerState == LEVEL3) ? 2'b11 : // *** not sure about this mux?
@ -448,12 +371,9 @@ module pagetablewalker
((PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00));
DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
//TranslationPAdr = TranslationVAdr[`PA_BITS-1:0];
NextWalkerState = IDLE;
end
FAULT: begin
//SelPTW = 1'b0;
FAULT: begin // *** why do these only get raised on TLB misses? Should they always fault?
NextWalkerState = IDLE;
WalkerInstrPageFaultF = ~DTLBMissMQ;
WalkerLoadPageFaultM = DTLBMissMQ && ~MemStore;
@ -467,15 +387,8 @@ module pagetablewalker
endcase
end
// *** Major issue. We need the full virtual address here.
// When the TLB's are update it use use the orignal address
// *** Currently truncate address to 32 bits. This must be changed if
// we support larger physical address spaces
assign HPTWPAdrE = {{(`XLEN-`PA_BITS){1'b0}}, TranslationPAdr[`PA_BITS-1:0]};
end
//endgenerate
end else begin
assign HPTWPAdrE = 0;
assign HPTWRead = 0;