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hptw: factored pregen

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This commit is contained in:
David Harris 2021-07-17 11:11:10 -04:00
parent 880aa1c03a
commit ef63e1ab52
2 changed files with 10 additions and 14 deletions
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23
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -29,11 +29,6 @@
`include "wally-config.vh" `include "wally-config.vh"
/* ***
TO-DO:
- Implement faults on accessed/dirty behavior
*/
module pagetablewalker module pagetablewalker
( (
// Control signals // Control signals
@ -152,6 +147,7 @@ module pagetablewalker
assign PageType = (PreviousWalkerState == LEVEL3) ? 2'b11 : // *** not sure about this mux? assign PageType = (PreviousWalkerState == LEVEL3) ? 2'b11 : // *** not sure about this mux?
((PreviousWalkerState == LEVEL2) ? 2'b10 : ((PreviousWalkerState == LEVEL2) ? 2'b10 :
((PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00)); ((PreviousWalkerState == LEVEL1) ? 2'b01 : 2'b00));
assign PRegEn = (NextWalkerState == LEVEL3) | (NextWalkerState == LEVEL2) | (NextWalkerState == LEVEL1) | (NextWalkerState == LEVEL0);
// *** is there a way to speed up HPTW? // *** is there a way to speed up HPTW?
@ -205,10 +201,9 @@ module pagetablewalker
// A megapage is a Level 1 leaf page. This page must have zero PPN[0]. // A megapage is a Level 1 leaf page. This page must have zero PPN[0].
assign MegapageMisaligned = |(CurrentPPN[9:0]); assign MegapageMisaligned = |(CurrentPPN[9:0]);
// State transition logic // State transition logic
always_comb begin always_comb begin
PRegEn = 1'b0; //PRegEn = 1'b0;
HPTWRead = 1'b0; HPTWRead = 1'b0;
case (WalkerState) case (WalkerState)
@ -220,7 +215,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL1_WDV; if (HPTWStall) NextWalkerState = LEVEL1_WDV;
else begin else begin
NextWalkerState = LEVEL1; NextWalkerState = LEVEL1;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL1: begin LEVEL1: begin
@ -236,7 +231,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL0_WDV; if (HPTWStall) NextWalkerState = LEVEL0_WDV;
else begin else begin
NextWalkerState = LEVEL0; NextWalkerState = LEVEL0;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL0: if (ValidPTE & LeafPTE & ~ADPageFault) NextWalkerState = LEAF; LEVEL0: if (ValidPTE & LeafPTE & ~ADPageFault) NextWalkerState = LEAF;
@ -265,7 +260,7 @@ module pagetablewalker
assign MegapageMisaligned = |(CurrentPPN[8:0]); assign MegapageMisaligned = |(CurrentPPN[8:0]);
always_comb begin always_comb begin
PRegEn = 1'b0; //PRegEn = 1'b0;
HPTWRead = 1'b0; HPTWRead = 1'b0;
case (WalkerState) case (WalkerState)
@ -277,7 +272,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL3_WDV; if (HPTWStall) NextWalkerState = LEVEL3_WDV;
else begin else begin
NextWalkerState = LEVEL3; NextWalkerState = LEVEL3;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL3: LEVEL3:
@ -290,7 +285,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL2_WDV; if (HPTWStall) NextWalkerState = LEVEL2_WDV;
else begin else begin
NextWalkerState = LEVEL2; NextWalkerState = LEVEL2;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL2: LEVEL2:
@ -303,7 +298,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL1_WDV; if (HPTWStall) NextWalkerState = LEVEL1_WDV;
else begin else begin
NextWalkerState = LEVEL1; NextWalkerState = LEVEL1;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL1: LEVEL1:
@ -316,7 +311,7 @@ module pagetablewalker
if (HPTWStall) NextWalkerState = LEVEL0_WDV; if (HPTWStall) NextWalkerState = LEVEL0_WDV;
else begin else begin
NextWalkerState = LEVEL0; NextWalkerState = LEVEL0;
PRegEn = 1'b1; //PRegEn = 1'b1;
end end
end end
LEVEL0: LEVEL0:

1
wally-pipelined/testbench/testbench-imperas.sv
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@ -746,6 +746,7 @@ module riscvassertions();
initial begin initial begin
assert (`PMP_ENTRIES == 0 || `PMP_ENTRIES==16 || `PMP_ENTRIES==64) else $error("Illegal number of PMP entries"); assert (`PMP_ENTRIES == 0 || `PMP_ENTRIES==16 || `PMP_ENTRIES==64) else $error("Illegal number of PMP entries");
assert (`F_SUPPORTED || ~`D_SUPPORTED) else $error("Can't support double without supporting float"); assert (`F_SUPPORTED || ~`D_SUPPORTED) else $error("Can't support double without supporting float");
assert (`XLEN == 64 || ~`D_SUPPORTED) else $error("Wally does not yet support D extensions on RV32");
end end
endmodule endmodule