class TLBContent:
- def __init__(self):
+ def __init__(self, pte_width):
+ self.pte_width = pte_width
self.flush_i = Signal() # Flush signal
# Update TLB
self.update_i = TLBUpdate()
# set by replacement strategy
# Lookup signals
self.lu_asid_i = Signal(ASID_WIDTH)
- self.lu_content_o = PTE()
+ self.lu_content_o = Signal(self.pte_width)
self.lu_is_2M_o = Signal()
self.lu_is_1G_o = Signal()
self.lu_hit_o = Signal()
m = Module()
tags = TLBEntry()
- content = PTE()
+ content = Signal(self.pte_width)
m.d.comb += self.lu_hit.eq(0)
# temporaries for 1st level match
- asid_ok = Signal()
- vpn2_ok = Signal()
- tags_ok = Signal()
- vpn2_hit = Signal()
+ asid_ok = Signal(reset_less=True)
+ vpn2_ok = Signal(reset_less=True)
+ tags_ok = Signal(reset_less=True)
+ vpn2_hit = Signal(reset_less=True)
m.d.comb += [tags_ok.eq(tags.valid),
asid_ok.eq(tags.asid == self.lu_asid_i),
vpn2_ok.eq(tags.vpn2 == self.vpn2),
vpn2_hit.eq(tags_ok & asid_ok & vpn2_ok)]
# temporaries for 2nd level match
- vpn1_ok = Signal()
- tags_2M = Signal()
- vpn0_ok = Signal()
- vpn0_or_2M = Signal()
+ vpn1_ok = Signal(reset_less=True)
+ tags_2M = Signal(reset_less=True)
+ vpn0_ok = Signal(reset_less=True)
+ vpn0_or_2M = Signal(reset_less=True)
m.d.comb += [vpn1_ok.eq(self.vpn1 == tags.vpn1),
tags_2M.eq(tags.is_2M),
vpn0_ok.eq(self.vpn0 == tags.vpn0),
# Update and Flush
# ------------------
- replace_valid = Signal()
+ replace_valid = Signal(reset_less=True)
m.d.comb += replace_valid.eq(self.update_i.valid & self.replace_en)
with m.If (self.flush_i):
# invalidate (flush) conditions: all if zero or just this ASID
tags.is_2M.eq(self.update_i.is_2M),
tags.valid.eq(1),
# and content as well
- content.eq(self.update_i.content)
+ content.eq(self.update_i.content.flatten())
]
return m
] + self.update_i.content.ports() + self.update_i.ports()
-class TLB:
+class PLRU:
def __init__(self):
- self.flush_i = Signal() # Flush signal
- # Update TLB
- self.update_i = TLBUpdate()
- # Lookup signals
+ self.lu_hit = Signal(TLB_ENTRIES)
+ self.replace_en = Signal(TLB_ENTRIES)
self.lu_access_i = Signal()
- self.lu_asid_i = Signal(ASID_WIDTH)
- self.lu_vaddr_i = Signal(64)
- self.lu_content_o = PTE()
- self.lu_is_2M_o = Signal()
- self.lu_is_1G_o = Signal()
- self.lu_hit_o = Signal()
def elaborate(self, platform):
m = Module()
- vpn2 = Signal(9)
- vpn1 = Signal(9)
- vpn0 = Signal(9)
-
- #-------------
- # Translation
- #-------------
- m.d.comb += [ vpn0.eq(self.lu_vaddr_i[12:21]),
- vpn1.eq(self.lu_vaddr_i[21:30]),
- vpn2.eq(self.lu_vaddr_i[30:39]),
- ]
-
- # SV39 defines three levels of page tables
- tc = []
- for i in range(TLB_ENTRIES):
- tlc = TLBContent()
- setattr(m.submodules, "tc%d" % i, tlc)
- tc.append(tlc)
- m.d.comb += [tlc.vpn0.eq(vpn0),
- tlc.vpn1.eq(vpn1),
- tlc.vpn2.eq(vpn2),
- tlc.flush_i.eq(self.flush_i),
- tlc.update_i.eq(self.update_i),
- tlc.lu_asid_i.eq(self.lu_asid_i)
- ]
-
- tc = Array(tc)
-
- # use Encoder to select hit index
- hitsel = Encoder(TLB_ENTRIES)
- m.submodules += hitsel
-
- hits = []
- for i in range(TLB_ENTRIES):
- hits.append(tc[i].lu_hit)
- m.d.comb += hitsel.i.eq(Cat(*hits))
- idx = hitsel.o
-
- active = Signal()
- m.d.comb += active.eq(~hitsel.n)
- with m.If(active):
- m.d.comb += [ self.lu_is_1G_o.eq(tc[idx].lu_is_1G_o),
- self.lu_is_2M_o.eq(tc[idx].lu_is_2M_o),
- self.lu_hit_o.eq(1),
- self.lu_content_o.eq(tc[idx].lu_content_o)
- ]
-
# -----------------------------------------------
# PLRU - Pseudo Least Recently Used Replacement
# -----------------------------------------------
for i in range(TLB_ENTRIES):
# we got a hit so update the pointer as it was least recently used
hit = Signal()
- m.d.comb += hit.eq(tc[i].lu_hit & self.lu_access_i)
+ m.d.comb += hit.eq(self.lu_hit[i] & self.lu_access_i)
with m.If(hit):
# Set the nodes to the values we would expect
for lvl in range(LOG_TLB):
print ("plru", i, en)
# boolean logic manipluation:
# plur0 & plru1 & plur2 == ~(~plru0 | ~plru1 | ~plru2)
- m.d.sync += tc[i].replace_en.eq(~Cat(*en).bool())
+ m.d.sync += self.replace_en[i].eq(~Cat(*en).bool())
+
+ return m
+
+
+class TLB:
+ def __init__(self):
+ self.flush_i = Signal() # Flush signal
+ # Lookup signals
+ self.lu_access_i = Signal()
+ self.lu_asid_i = Signal(ASID_WIDTH)
+ self.lu_vaddr_i = Signal(64)
+ self.lu_content_o = PTE()
+ self.lu_is_2M_o = Signal()
+ self.lu_is_1G_o = Signal()
+ self.lu_hit_o = Signal()
+ # Update TLB
+ self.pte_width = len(self.lu_content_o.flatten())
+ self.update_i = TLBUpdate()
+
+ def elaborate(self, platform):
+ m = Module()
+
+ vpn2 = Signal(9)
+ vpn1 = Signal(9)
+ vpn0 = Signal(9)
+
+ #-------------
+ # Translation
+ #-------------
+ m.d.comb += [ vpn0.eq(self.lu_vaddr_i[12:21]),
+ vpn1.eq(self.lu_vaddr_i[21:30]),
+ vpn2.eq(self.lu_vaddr_i[30:39]),
+ ]
+
+ # SV39 defines three levels of page tables
+ tc = []
+ for i in range(TLB_ENTRIES):
+ tlc = TLBContent(self.pte_width)
+ setattr(m.submodules, "tc%d" % i, tlc)
+ tc.append(tlc)
+ # connect inputs
+ m.d.comb += [tlc.vpn0.eq(vpn0),
+ tlc.vpn1.eq(vpn1),
+ tlc.vpn2.eq(vpn2),
+ tlc.flush_i.eq(self.flush_i),
+ tlc.update_i.eq(self.update_i),
+ tlc.lu_asid_i.eq(self.lu_asid_i)]
+ tc = Array(tc)
+
+ #--------------
+ # Select hit
+ #--------------
+
+ # use Encoder to select hit index
+ # XXX TODO: assert that there's only one valid entry
+ hitsel = Encoder(TLB_ENTRIES)
+ m.submodules.hitsel = hitsel
+
+ hits = []
+ for i in range(TLB_ENTRIES):
+ hits.append(tc[i].lu_hit)
+ m.d.comb += hitsel.i.eq(Cat(*hits))
+ idx = hitsel.o
+
+ active = Signal()
+ m.d.comb += active.eq(~hitsel.n)
+ with m.If(active):
+ # active hit, send selected as output
+ m.d.comb += [ self.lu_is_1G_o.eq(tc[idx].lu_is_1G_o),
+ self.lu_is_2M_o.eq(tc[idx].lu_is_2M_o),
+ self.lu_hit_o.eq(1),
+ self.lu_content_o.flatten().eq(tc[idx].lu_content_o),
+ ]
+
+ #--------------
+ # PLRU.
+ #--------------
+
+ p = PLRU()
+ m.submodules.plru = p
+
+ # connect PLRU inputs/outputs
+ en = []
+ for i in range(TLB_ENTRIES):
+ en.append(tc[i].replace_en)
+ m.d.comb += [Cat(*en).eq(p.replace_en), # output from PLRU into tags
+ p.lu_hit.eq(hitsel.i),
+ p.lu_access_i.eq(self.lu_access_i)]
#--------------
# Sanity checks
projects / soc.git / commitdiff