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HPTW: more cleanup

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This commit is contained in:
David Harris 2021-07-17 04:55:01 -04:00
parent b74f3b14ec
commit 1595e4f992
1 changed files with 17 additions and 59 deletions
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76
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -95,21 +95,11 @@ module pagetablewalker
logic StartWalk;
logic EndWalk;
typedef enum {LEVEL0_SET_ADRE,
LEVEL0_WDV,
LEVEL0,
LEVEL1_SET_ADRE,
LEVEL1_WDV,
LEVEL1,
LEVEL2_SET_ADRE,
LEVEL2_WDV,
LEVEL2,
LEVEL3_SET_ADRE,
LEVEL3_WDV,
LEVEL3,
LEAF,
IDLE,
FAULT} statetype;
typedef enum {LEVEL0_SET_ADRE, LEVEL0_WDV, LEVEL0,
LEVEL1_SET_ADRE, LEVEL1_WDV, LEVEL1,
LEVEL2_SET_ADRE, LEVEL2_WDV, LEVEL2,
LEVEL3_SET_ADRE, LEVEL3_WDV, LEVEL3,
LEAF, IDLE, FAULT} statetype;
statetype WalkerState, NextWalkerState, PreviousWalkerState;
@ -117,13 +107,8 @@ module pagetablewalker
logic SelDataTranslation;
logic AnyTLBMissM;
assign SvMode = SATP_REGW[`XLEN-1:`XLEN-`SVMODE_BITS];
assign BasePageTablePPN = SATP_REGW[`PPN_BITS-1:0];
assign MemStore = MemRWM[0];
// Prefer data address translations over instruction address translations
@ -137,7 +122,6 @@ module pagetablewalker
flopenr #(`XLEN) PTEReg(clk, reset, PRegEn, HPTWReadPTE, CurrentPTE); // Capture page table entry from data cache
assign CurrentPPN = CurrentPTE[`PPN_BITS+9:10];
assign AnyTLBMissM = DTLBMissM | ITLBMissF;
assign StartWalk = (WalkerState == IDLE) & AnyTLBMissM;
@ -161,6 +145,14 @@ module pagetablewalker
assign DTLBWriteM = (WalkerState == LEAF) & DTLBMissMQ;
assign ITLBWriteF = (WalkerState == LEAF) & ~DTLBMissMQ;
assign WalkerInstrPageFaultF = (WalkerState == FAULT) & ~DTLBMissMQ; //*** why do these only get raised on TLB misses? Should they always fault even for ADpagefaults, invalid addresses,etc??
assign WalkerLoadPageFaultM = (WalkerState == FAULT) & DTLBMissMQ & ~MemStore;
assign WalkerStorePageFaultM = (WalkerState == FAULT) & DTLBMissMQ & MemStore;
assign PageType = (PreviousWalkerState == LEVEL3) ? 2'b11 : // *** not sure about this mux?
((PreviousWalkerState == LEVEL2) ? 2'b10 :
((PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00));
// *** is there a way to speed up HPTW?
// TranslationPAdr mux
@ -218,11 +210,6 @@ module pagetablewalker
always_comb begin
PRegEn = 1'b0;
HPTWRead = 1'b0;
PageType = '0;
WalkerInstrPageFaultF = 1'b0;
WalkerLoadPageFaultM = 1'b0;
WalkerStorePageFaultM = 1'b0;
case (WalkerState)
IDLE: if (AnyTLBMissM & SvMode == `SV32) NextWalkerState = LEVEL1_SET_ADRE;
@ -254,27 +241,13 @@ module pagetablewalker
end
LEVEL0: if (ValidPTE & LeafPTE & ~ADPageFault) NextWalkerState = LEAF;
else NextWalkerState = FAULT;
LEAF: begin
NextWalkerState = IDLE;
PageType = (PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00; // *** not sure about this mux?
end
FAULT: begin
NextWalkerState = IDLE;
WalkerInstrPageFaultF = ~DTLBMissMQ;
WalkerLoadPageFaultM = DTLBMissMQ && ~MemStore;
WalkerStorePageFaultM = DTLBMissMQ && MemStore;
end
LEAF: NextWalkerState = IDLE;
FAULT: NextWalkerState = IDLE;
// Default case should never happen, but is included for linter.
default: NextWalkerState = IDLE;
endcase
end
// Assign outputs to ahblite
// *** Currently truncate address to 32 bits. This must be changed if
// we support larger physical address spaces
@ -294,11 +267,6 @@ module pagetablewalker
always_comb begin
PRegEn = 1'b0;
HPTWRead = 1'b0;
PageType = '0;
WalkerInstrPageFaultF = 1'b0;
WalkerLoadPageFaultM = 1'b0;
WalkerStorePageFaultM = 1'b0;
case (WalkerState)
IDLE: if (AnyTLBMissM) NextWalkerState = (SvMode == `SV48) ? LEVEL3_SET_ADRE : LEVEL2_SET_ADRE;
@ -354,18 +322,8 @@ module pagetablewalker
LEVEL0:
if (ValidPTE && LeafPTE && ~ADPageFault) NextWalkerState = LEAF;
else NextWalkerState = FAULT;
LEAF: begin
PageType = (PreviousWalkerState == LEVEL3) ? 2'b11 : // *** not sure about this mux?
((PreviousWalkerState == LEVEL2) ? 2'b10 :
((PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00));
NextWalkerState = IDLE;
end
FAULT: begin // *** why do these only get raised on TLB misses? Should they always fault?
NextWalkerState = IDLE;
WalkerInstrPageFaultF = ~DTLBMissMQ;
WalkerLoadPageFaultM = DTLBMissMQ && ~MemStore;
WalkerStorePageFaultM = DTLBMissMQ && MemStore;
end
LEAF: NextWalkerState = IDLE;
FAULT: NextWalkerState = IDLE;
default: NextWalkerState = IDLE; // should never be reached
endcase