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Added comments about PMP checker fixes when test cases will be ready to initialize PMP before entering user mode

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This commit is contained in:
David Harris 2023-03-19 05:46:34 -07:00
parent 031cc6967a
commit 02e7e7d011
1 changed files with 7 additions and 5 deletions
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8
src/mmu/pmpchecker.sv
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@ -50,14 +50,14 @@ module pmpchecker (
);
// Bit i is high when the address falls in PMP region i
logic EnforcePMP;
logic EnforcePMP; // should PMP be checked in this privilege level
logic [`PMP_ENTRIES-1:0] Match; // physical address matches one of the pmp ranges
logic [`PMP_ENTRIES-1:0] FirstMatch; // onehot encoding for the first pmpaddr to match the current address.
logic [`PMP_ENTRIES-1:0] Active; // PMP register i is non-null
logic [`PMP_ENTRIES-1:0] L, X, W, R; // PMP matches and has flag set
logic [`PMP_ENTRIES-1:0] PAgePMPAdr; // for TOR PMP matching, PhysicalAddress > PMPAdr[i]
if (`PMP_ENTRIES > 0)
if (`PMP_ENTRIES > 0) // prevent complaints about array of no elements when PMP_ENTRIES = 0
pmpadrdec pmpadrdecs[`PMP_ENTRIES-1:0](
.PhysicalAddress,
.PMPCfg(PMPCFG_ARRAY_REGW),
@ -68,8 +68,10 @@ module pmpchecker (
priorityonehot #(`PMP_ENTRIES) pmppriority(.a(Match), .y(FirstMatch)); // combine the match signal from all the adress decoders to find the first one that matches.
// Only enforce PMP checking for S and U modes when at least one PMP is active or in Machine mode when L bit is set in selected region
// Only enforce PMP checking for S and U modes or in Machine mode when L bit is set in selected region
assign EnforcePMP = (PrivilegeModeW == `M_MODE) ? |(L & FirstMatch) : |Active;
// assign EnforcePMP = (PrivilegeModeW != `M_MODE) | |(L & FirstMatch); // *** switch to this logic when PMP is initialized for non-machine mode
// *** remove unused Active lines from pmpadrdecs
assign PMPInstrAccessFaultF = EnforcePMP & ExecuteAccessF & ~|(X & FirstMatch) ;
assign PMPStoreAmoAccessFaultM = EnforcePMP & WriteAccessM & ~|(W & FirstMatch) ;