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Avoid data corruption under correctable tag error during flush 

This esoteric bug manifests if a tag-read error occurs when a FENCE.I is
executed, even if the error was correctable.  Subsequently, an attempt to
flush a dirty line may flush the wrong line's data.
This commit is contained in:
Andrew Waterman 2017-11-29 00:31:30 -08:00
parent 34d86ef665
commit 890528c641
1 changed files with 4 additions and 4 deletions
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8
src/main/scala/rocket/DCache.scala
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@ -196,7 +196,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s1_tag = s1_paddr >> untagBits
val s1_meta_hit_way = s1_meta_uncorrected.map(r => r.coh.isValid() && r.tag === s1_tag).asUInt
val s1_meta_hit_state = ClientMetadata.onReset.fromBits(
s1_meta_uncorrected.map(r => Mux(r.tag === s1_tag, r.coh.asUInt, UInt(0)))
s1_meta_uncorrected.map(r => Mux(r.tag === s1_tag && !s1_flush_valid, r.coh.asUInt, UInt(0)))
.reduce (_|_))
(s1_meta_hit_way, s1_meta_hit_state, s1_meta, s1_meta_uncorrected(s1_victim_way))
}
@ -243,7 +243,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s2_probe_way = RegEnable(s1_hit_way, s1_probe)
val s2_probe_state = RegEnable(s1_hit_state, s1_probe)
val s2_hit_way = RegEnable(s1_hit_way, s1_valid_not_nacked)
val s2_hit_state = RegEnable(s1_hit_state, s1_valid_not_nacked)
val s2_hit_state = RegEnable(s1_hit_state, s1_valid_not_nacked || s1_flush_valid)
val s2_waw_hazard = RegEnable(s1_waw_hazard, s1_valid_not_nacked)
val s2_store_merge = Wire(Bool())
val s2_hit_valid = s2_hit_state.isValid()
@ -262,9 +262,9 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s2_valid_cached_miss = s2_valid_miss && !s2_uncached && !uncachedInFlight.asUInt.orR
val s2_victimize = Bool(!usingDataScratchpad) && (s2_valid_cached_miss || s2_valid_data_error || s2_flush_valid)
val s2_valid_uncached_pending = s2_valid_miss && s2_uncached && !uncachedInFlight.asUInt.andR
val s2_victim_way = Mux(s2_hit_valid && !s2_flush_valid_pre_tag_ecc, s2_hit_way, UIntToOH(RegEnable(s1_victim_way, s1_valid_not_nacked || s1_flush_valid)))
val s2_victim_way = Mux(s2_hit_valid, s2_hit_way, UIntToOH(RegEnable(s1_victim_way, s1_valid_not_nacked || s1_flush_valid)))
val s2_victim_tag = Mux(s2_valid_data_error, s2_req.addr >> untagBits, RegEnable(s1_victim_meta.tag, s1_valid_not_nacked || s1_flush_valid))
val s2_victim_state = Mux(s2_hit_valid && !s2_flush_valid, s2_hit_state, RegEnable(s1_victim_meta.coh, s1_valid_not_nacked || s1_flush_valid))
val s2_victim_state = Mux(s2_hit_valid, s2_hit_state, RegEnable(s1_victim_meta.coh, s1_valid_not_nacked || s1_flush_valid))
val (s2_prb_ack_data, s2_report_param, probeNewCoh)= s2_probe_state.onProbe(probe_bits.param)
val (s2_victim_dirty, s2_shrink_param, voluntaryNewCoh) = s2_victim_state.onCacheControl(M_FLUSH)