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Merge pull request #597 from davidharrishmc/dev

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Misaligned AMO throws Access-Fault; coverage improvements
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Rose Thompson 2024-01-26 09:52:31 -06:00 committed by GitHub
commit 6f3f839d8d
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3 changed files with 33 additions and 15 deletions
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6
src/fpu/fpu.sv
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@ -211,7 +211,8 @@ module fpu import cvw::*; #(parameter cvw_t P) (
{{P.FLEN-P.D_LEN{1'b1}}, 2'b0, {P.D_NE-1{1'b1}}, (P.D_NF)'(0)},
{{P.FLEN-P.H_LEN{1'b1}}, 2'b0, {P.H_NE-1{1'b1}}, (P.H_NF)'(0)},
{2'b0, {P.NE-1{1'b1}}, (P.NF)'(0)}, FmtE, BoxedOneE); // NaN boxing zeroes
assign FmaAddSubE = OpCtrlE[2]&OpCtrlE[1]&(FResSelE==2'b01)&(PostProcSelE==2'b10);
assign FmaAddSubE = OpCtrlE[2]&OpCtrlE[1]&(PostProcSelE==2'b10);
// ***simplified from appearently redundant assign FmaAddSubE = OpCtrlE[2]&OpCtrlE[1]&(FResSelE==2'b01)&(PostProcSelE==2'b10);
mux2 #(P.FLEN) fyaddmux (PreYE, BoxedOneE, FmaAddSubE, YE); // Force Y to be 1 for add/subtract
// Select NAN-boxed value of Z = 0.0 in proper format for FMA for multiply X*Y+Z
@ -352,7 +353,8 @@ module fpu import cvw::*; #(parameter cvw_t P) (
.PostProcSel(PostProcSelM), .PostProcRes(PostProcResM), .PostProcFlg(PostProcFlgM), .FCvtIntRes(FCvtIntResM));
// FPU flag selection - to privileged
mux2 #(5) FPUFlgMux({PreNVM&~FResSelM[1], 4'b0}, PostProcFlgM, ~FResSelM[1]&FResSelM[0], SetFflagsM);
//mux2 #(5) FPUFlgMux({PreNVM&~FResSelM[1], 4'b0}, PostProcFlgM, ~FResSelM[1]&FResSelM[0], SetFflagsM);
mux2 #(5) FPUFlgMux({PreNVM, 4'b0}, PostProcFlgM, (FResSelM == 2'b01), SetFflagsM);
mux2 #(P.FLEN) FPUResMux(PreFpResM, PostProcResM, FResSelM[0], FpResM);
// M/W pipe registers

26
src/mmu/mmu.sv
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@ -74,6 +74,8 @@ module mmu import cvw::*; #(parameter cvw_t P,
logic TLBPageFault; // Page fault from TLB
logic ReadNoAmoAccessM; // Read that is not part of atomic operation causes Load faults. Otherwise StoreAmo faults
logic [1:0] PBMemoryType; // PBMT field of PTE during TLB hit, or 00 otherwise
logic AmoMisalignedCausesAccessFaultM; // Misaligned AMO is not handled by hardware even with ZICCLSM, so it throws an access fault instead of misaligned with ZICCLSM
logic AmoAccessM; // AMO access detected when ReadAccessM and WriteAccessM are simultaneously asserted
// only instantiate TLB if Virtual Memory is supported
if (P.VIRTMEM_SUPPORTED) begin:tlb
@ -123,24 +125,30 @@ module mmu import cvw::*; #(parameter cvw_t P,
assign PMPLoadAccessFaultM = 0;
end
assign ReadNoAmoAccessM = ReadAccessM & ~WriteAccessM;// AMO causes StoreAmo rather than Load fault
// Access faults
// If TLB miss and translating we want to not have faults from the PMA and PMP checkers.
assign InstrAccessFaultF = (PMAInstrAccessFaultF | PMPInstrAccessFaultF) & ~TLBMiss;
assign LoadAccessFaultM = (PMALoadAccessFaultM | PMPLoadAccessFaultM) & ~TLBMiss;
assign StoreAmoAccessFaultM = (PMAStoreAmoAccessFaultM | PMPStoreAmoAccessFaultM) & ~TLBMiss;
assign ReadNoAmoAccessM = ReadAccessM & ~WriteAccessM;// AMO causes StoreAmo rather than Load fault
assign AmoAccessM = ReadAccessM & WriteAccessM;
// Misaligned faults
always_comb // exclusion-tag: immu-wordaccess
always_comb // exclusion-tag: immu-wordaccess
case(Size[1:0])
2'b00: DataMisalignedM = 0; // lb, sb, lbu
2'b01: DataMisalignedM = VAdr[0]; // lh, sh, lhu
2'b10: DataMisalignedM = VAdr[1] | VAdr[0]; // lw, sw, flw, fsw, lwu
2'b11: DataMisalignedM = |VAdr[2:0]; // ld, sd, fld, fsd
endcase
// When ZiCCLSM_SUPPORTED, misalgined cachable loads and stores are handled in hardware so they do not throw a misaligned fault
assign LoadMisalignedFaultM = DataMisalignedM & ReadNoAmoAccessM & ~(P.ZICCLSM_SUPPORTED & Cacheable);
assign StoreAmoMisalignedFaultM = DataMisalignedM & WriteAccessM & (~(P.ZICCLSM_SUPPORTED & Cacheable) | ReadAccessM); // Misaligned AMO faults even if ZICCLSM supported
assign StoreAmoMisalignedFaultM = DataMisalignedM & WriteAccessM & ~(P.ZICCLSM_SUPPORTED & Cacheable); // Store and AMO both assert WriteAccess
// Access faults
// If TLB miss and translating we want to not have faults from the PMA and PMP checkers.
assign InstrAccessFaultF = (PMAInstrAccessFaultF | PMPInstrAccessFaultF) & ~TLBMiss;
assign LoadAccessFaultM = (PMALoadAccessFaultM | PMPLoadAccessFaultM) & ~TLBMiss;
// a misaligned AMO causes an access fault rather than a misaligned fault if a misaligned load/store is handled in hardware
// this is subtle - see privileged spec 3.6.3.3
// AMO is detected as ReadAccess & WriteAccess
assign AmoMisalignedCausesAccessFaultM = DataMisalignedM & AmoAccessM & (P.ZICCLSM_SUPPORTED & Cacheable);
assign StoreAmoAccessFaultM = (PMAStoreAmoAccessFaultM | PMPStoreAmoAccessFaultM | AmoMisalignedCausesAccessFaultM) & ~TLBMiss;
// Specify which type of page fault is occurring
assign InstrPageFaultF = TLBPageFault & ExecuteAccessF;

16
tests/coverage/tlbmisc.S
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@ -95,7 +95,7 @@ main:
sw t1, 0(t0) # write to page
jalr ra, t0 # jump to page
# Nonleaf PTE has PBMT != 0 # this should cause a page fault during page walking. However, as of issue 546 1/1/24, both ImperasDV and Wally don't detect this
# Nonleaf PTE has PBMT != 0 causes a page fault during page walking. H
li t0, 0x80600000
lw t1, 0(t0) # read from page
sw t1, 0(t0) # write to page
@ -104,14 +104,21 @@ main:
# jump to address for TLB miss to trigger HPTW to make access with DisableTranslation = 1, Translate = 0
li t0, 0x80805000
jalr ra, t0
li t0, 0x80807000 # again, triggering setting access bit
jalr ra, t0
# atomic access to uncachable memory
#li t0, 0x80806000
#sd zero, 0(t0)
#amoadd.w t1, t0, (t0)
# Good PBMT with menvcfg.PBMTE = 0
li t0, 3
li a0, 3
ecall # switch to machine mode
li t5, 0x1
slli t5, t5, 62
csrc menvcfg, t5 # menvcfg.PBMTE = 0
li t0, 1
li a0, 1
ecall # switch back to supervisor mode
li t0, 0x80806000
jalr ra, t0 # jump to page to exercise ITLB with PBMT !=0 when ENVCFG_PMTE=0
@ -365,6 +372,7 @@ pagetable:
.8byte 0x00000000200000C3 # valid r for VA 80802000
.8byte 0x00000000200000C9 # valid x for VA 80803000
.8byte 0x00000000200000CD # valid wx for VA 80804000 (illegal combination, but used to test tlbcontrol)
.8byte 0x000000002000000F # valid rwx for VA 80805000 for covering ITLB translate and UpdateDA
.8byte 0x00000000200000CF # valid rwx for VA 80805000 for covering ITLB translate
.8byte 0x20000000200000CF # PBMT=1 for VA 80806000 for covering ITLB BadPBMT
.8byte 0x000000002000000F # valid rwx for VA 80807000 for covering UpdateDA