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Moved lsu interlock fpm to separate module.

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This commit is contained in:
Ross Thompson 2021-12-29 17:40:24 -06:00
parent 81741925aa
commit 90ccc94e5e
4 changed files with 131 additions and 83 deletions
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2
wally-pipelined/regression/wave.do
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@ -205,7 +205,7 @@ add wave -noupdate -group AHB /testbench/dut/hart/ebu/HMASTLOCK
add wave -noupdate -group AHB /testbench/dut/hart/ebu/HADDRD
add wave -noupdate -group AHB /testbench/dut/hart/ebu/HSIZED
add wave -noupdate -group AHB /testbench/dut/hart/ebu/HWRITED
add wave -noupdate -expand -group lsu -color Gold /testbench/dut/hart/lsu/MEM_VIRTMEM/InterlockCurrState
add wave -noupdate -expand -group lsu -color Gold /testbench/dut/hart/lsu/MEM_VIRTMEM/interlockfsm/InterlockCurrState
add wave -noupdate -expand -group lsu /testbench/dut/hart/lsu/SelHPTW
add wave -noupdate -expand -group lsu /testbench/dut/hart/lsu/InterlockStall
add wave -noupdate -expand -group lsu /testbench/dut/hart/lsu/LSUStall

2
wally-pipelined/src/lsu/busfsm.sv
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@ -1,7 +1,7 @@
///////////////////////////////////////////
// busfsm.sv
//
// Written: Ross Thompson ross1728@gmail.com
// Written: Ross Thompson ross1728@gmail.com December 29, 2021
// Modified:
//
// Purpose: Load/Store Unit's interface to BUS

113
wally-pipelined/src/lsu/interlockfsm.sv Normal file
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@ -0,0 +1,113 @@
///////////////////////////////////////////
// interlockfsm.sv
//
// Written: Ross Thompson ross1728@gmail.com December 29, 2021
// Modified:
//
// Purpose: Allows the HPTW to take control of the dcache to walk page table and then replay the memory operation if
// there was on.
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
///////////////////////////////////////////
`include "wally-config.vh"
module interlockfsm
(input logic clk,
input logic reset,
input logic AnyCPUReqM,
input logic ITLBMissF,
input logic ITLBWriteF,
input logic DTLBMissM,
input logic DTLBWriteM,
input logic ExceptionM,
input logic PendingInterruptM,
input logic DCacheStall,
output logic InterlockStall,
output logic SelReplayCPURequest,
output logic SelHPTW,
output logic IgnoreRequest);
typedef enum {STATE_T0_READY,
STATE_T0_REPLAY,
STATE_T3_DTLB_MISS,
STATE_T4_ITLB_MISS,
STATE_T5_ITLB_MISS,
STATE_T7_DITLB_MISS} statetype;
statetype InterlockCurrState, InterlockNextState;
always_ff @(posedge clk)
if (reset) InterlockCurrState <= #1 STATE_T0_READY;
else InterlockCurrState <= #1 InterlockNextState;
always_comb begin
case(InterlockCurrState)
STATE_T0_READY: if(~ITLBMissF & DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T3_DTLB_MISS;
else if(ITLBMissF & ~DTLBMissM & ~AnyCPUReqM) InterlockNextState = STATE_T4_ITLB_MISS;
else if(ITLBMissF & ~DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T5_ITLB_MISS;
else if(ITLBMissF & DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T7_DITLB_MISS;
else InterlockNextState = STATE_T0_READY;
STATE_T0_REPLAY: if(DCacheStall) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T0_READY;
STATE_T3_DTLB_MISS: if(DTLBWriteM) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T3_DTLB_MISS;
STATE_T4_ITLB_MISS: if(ITLBWriteF) InterlockNextState = STATE_T0_READY;
else InterlockNextState = STATE_T4_ITLB_MISS;
STATE_T5_ITLB_MISS: if(ITLBWriteF) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T5_ITLB_MISS;
STATE_T7_DITLB_MISS: if(DTLBWriteM) InterlockNextState = STATE_T5_ITLB_MISS;
else InterlockNextState = STATE_T7_DITLB_MISS;
default: InterlockNextState = STATE_T0_READY;
endcase
end // always_comb
// signal to CPU it needs to wait on HPTW.
/* -----\/----- EXCLUDED -----\/-----
// this code has a problem with imperas64mmu as it reads in an invalid uninitalized instruction. InterlockStall becomes x and it propagates
// everywhere. The case statement below implements the same logic but any x on the inputs will resolve to 0.
// Note this will cause a problem for post synthesis gate simulation.
assign InterlockStall = (InterlockCurrState == STATE_T0_READY & (DTLBMissM | ITLBMissF)) |
(InterlockCurrState == STATE_T3_DTLB_MISS) | (InterlockCurrState == STATE_T4_ITLB_MISS) |
(InterlockCurrState == STATE_T5_ITLB_MISS) | (InterlockCurrState == STATE_T7_DITLB_MISS);
-----/\----- EXCLUDED -----/\----- */
always_comb begin
InterlockStall = 1'b0;
case(InterlockCurrState)
STATE_T0_READY: if(DTLBMissM | ITLBMissF) InterlockStall = 1'b1;
STATE_T3_DTLB_MISS: InterlockStall = 1'b1;
STATE_T4_ITLB_MISS: InterlockStall = 1'b1;
STATE_T5_ITLB_MISS: InterlockStall = 1'b1;
STATE_T7_DITLB_MISS: InterlockStall = 1'b1;
default: InterlockStall = 1'b0;
endcase
end
assign SelReplayCPURequest = (InterlockNextState == STATE_T0_REPLAY);
assign SelHPTW = (InterlockCurrState == STATE_T3_DTLB_MISS) | (InterlockCurrState == STATE_T4_ITLB_MISS) |
(InterlockCurrState == STATE_T5_ITLB_MISS) | (InterlockCurrState == STATE_T7_DITLB_MISS);
assign IgnoreRequest = (InterlockCurrState == STATE_T0_READY & (ITLBMissF | DTLBMissM | ExceptionM | PendingInterruptM)) |
((InterlockCurrState == STATE_T0_REPLAY)
& (ExceptionM | PendingInterruptM));
endmodule

97
wally-pipelined/src/lsu/lsu.sv
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@ -128,78 +128,13 @@ module lsu
logic [2:0] HPTWSize;
logic SelReplayCPURequest;
typedef enum {STATE_T0_READY,
STATE_T0_REPLAY,
STATE_T3_DTLB_MISS,
STATE_T4_ITLB_MISS,
STATE_T5_ITLB_MISS,
STATE_T7_DITLB_MISS} statetype;
assign AnyCPUReqM = (|MemRWM) | (|AtomicM);
statetype InterlockCurrState, InterlockNextState;
assign AnyCPUReqM = (|MemRWM) | (|AtomicM);
always_ff @(posedge clk)
if (reset) InterlockCurrState <= #1 STATE_T0_READY;
else InterlockCurrState <= #1 InterlockNextState;
always_comb begin
case(InterlockCurrState)
STATE_T0_READY: if(~ITLBMissF & DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T3_DTLB_MISS;
else if(ITLBMissF & ~DTLBMissM & ~AnyCPUReqM) InterlockNextState = STATE_T4_ITLB_MISS;
else if(ITLBMissF & ~DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T5_ITLB_MISS;
else if(ITLBMissF & DTLBMissM & AnyCPUReqM) InterlockNextState = STATE_T7_DITLB_MISS;
else InterlockNextState = STATE_T0_READY;
STATE_T0_REPLAY: if(DCacheStall) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T0_READY;
STATE_T3_DTLB_MISS: if(DTLBWriteM) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T3_DTLB_MISS;
STATE_T4_ITLB_MISS: if(ITLBWriteF) InterlockNextState = STATE_T0_READY;
else InterlockNextState = STATE_T4_ITLB_MISS;
STATE_T5_ITLB_MISS: if(ITLBWriteF) InterlockNextState = STATE_T0_REPLAY;
else InterlockNextState = STATE_T5_ITLB_MISS;
STATE_T7_DITLB_MISS: if(DTLBWriteM) InterlockNextState = STATE_T5_ITLB_MISS;
else InterlockNextState = STATE_T7_DITLB_MISS;
default: InterlockNextState = STATE_T0_READY;
endcase
end // always_comb
interlockfsm interlockfsm (.clk, .reset, .AnyCPUReqM, .ITLBMissF, .ITLBWriteF,
.DTLBMissM, .DTLBWriteM, .ExceptionM, .PendingInterruptM, .DCacheStall,
.InterlockStall, .SelReplayCPURequest, .SelHPTW,
.IgnoreRequest);
// signal to CPU it needs to wait on HPTW.
/* -----\/----- EXCLUDED -----\/-----
// this code has a problem with imperas64mmu as it reads in an invalid uninitalized instruction. InterlockStall becomes x and it propagates
// everywhere. The case statement below implements the same logic but any x on the inputs will resolve to 0.
assign InterlockStall = (InterlockCurrState == STATE_T0_READY & (DTLBMissM | ITLBMissF)) |
(InterlockCurrState == STATE_T3_DTLB_MISS) | (InterlockCurrState == STATE_T4_ITLB_MISS) |
(InterlockCurrState == STATE_T5_ITLB_MISS) | (InterlockCurrState == STATE_T7_DITLB_MISS);
-----/\----- EXCLUDED -----/\----- */
always_comb begin
InterlockStall = 1'b0;
case(InterlockCurrState)
STATE_T0_READY: if(DTLBMissM | ITLBMissF) InterlockStall = 1'b1;
STATE_T3_DTLB_MISS: InterlockStall = 1'b1;
STATE_T4_ITLB_MISS: InterlockStall = 1'b1;
STATE_T5_ITLB_MISS: InterlockStall = 1'b1;
STATE_T7_DITLB_MISS: InterlockStall = 1'b1;
default: InterlockStall = 1'b0;
endcase
end
// When replaying CPU memory request after PTW select the IEUAdrM for correct address.
assign SelReplayCPURequest = (InterlockNextState == STATE_T0_REPLAY);
assign SelHPTW = (InterlockCurrState == STATE_T3_DTLB_MISS) | (InterlockCurrState == STATE_T4_ITLB_MISS) |
(InterlockCurrState == STATE_T5_ITLB_MISS) | (InterlockCurrState == STATE_T7_DITLB_MISS);
assign IgnoreRequest = (InterlockCurrState == STATE_T0_READY & (ITLBMissF | DTLBMissM | ExceptionM | PendingInterruptM)) |
((InterlockCurrState == STATE_T0_REPLAY)
& (ExceptionM | PendingInterruptM));
// *** add generate to conditionally create hptw, lsuArb, and mmu
// based on `MEM_VIRTMEM
hptw hptw(.clk, .reset, .SATP_REGW, .PCF, .IEUAdrM,
.ITLBMissF(ITLBMissF & ~PendingInterruptM),
.DTLBMissM(DTLBMissM & ~PendingInterruptM),
@ -216,25 +151,18 @@ module lsu
mux2 #(12) adremux(IEUAdrE[11:0], HPTWAdr[11:0], SelHPTW, LsuAdrE);
mux2 #(`PA_BITS) lsupadrmux(IEUAdrExtM[`PA_BITS-1:0], HPTWAdr, SelHPTW, PreLsuPAdrM);
// always block interrupts when using the hardware page table walker.
assign CPUBusy = StallW & ~SelHPTW;
// always block interrupts when using the hardware page table walker.
// this is for the d cache SRAM.
// turns out because we cannot pipeline hptw requests we don't need this register
// It is not possible to pipeline hptw as the following load will depend on the previous load's
// data. Therefore we don't need a pipeline register
//flop #(`PA_BITS) HPTWAdrMReg(clk, HPTWAdr, HPTWAdrM); // delay HPTWAdrM by a cycle
//assign PreLsuRWM = SelHPTW ? {HPTWRead, 1'b0} : MemRWM;
//assign LsuAdrE = SelHPTW ? HPTWAdr[11:0] : IEUAdrE[11:0];
//assign LsuAtomicM = SelHPTW ? 2'b00 : AtomicM;
//assign PreLsuPAdrM = SelHPTW ? HPTWAdr : IEUAdrExtM[`PA_BITS-1:0];
// Specify which type of page fault is occurring
// *** `MEM_VIRTMEM
assign DTLBLoadPageFaultM = DTLBPageFaultM & PreLsuRWM[1];
assign DTLBStorePageFaultM = DTLBPageFaultM & PreLsuRWM[0];
// When replaying CPU memory request after PTW select the IEUAdrM for correct address.
assign DCacheAdrE = SelReplayCPURequest ? IEUAdrM[11:0] : LsuAdrE;
end // if (`MEM_VIRTMEM)
@ -263,6 +191,13 @@ module lsu
endgenerate
// **** look into this confusing signal.
// This signal is confusing. CommittedM tells the CPU's trap unit the current instruction
// in the memory stage is a memory operaton and that memory operation is either completed
// or is partially executed. This signal is only low for the first cycle of a memory
// operation.
// **** I think there is also a bug here. Data cache misses and TLB misses both
// set this bit in the first cycle. It is not strickly wrong, but it may be better
// to flush the memory operation at that time.
assign CommittedM = SelHPTW | DCacheCommittedM | BusCommittedM;
generate