def msr_copy(msr_o, msr_i, zero_me=True):
- """msr_copy
+ """msr_copy (also used to copy relevant bits into SRR1)
+
ISA says this:
Defined MSR bits are classified as either full func tion or partial
function. Full function MSR bits are saved in SRR1 or HSRR1 when
super().__init__(pspec, "main")
self.fields = DecodeFields(SignalBitRange, [self.i.ctx.op.insn])
self.fields.create_specs()
+ self.kaivb = Signal(64) # KAIVB SPR
def trap(self, m, trap_addr, return_addr):
"""trap. sets new PC, stores MSR and old PC in SRR1 and SRR0
op = self.i.ctx.op
msr_i = op.msr
svstate_i = op.svstate
+
+ exc = LDSTException("trapexc")
+ comb += exc.eq(op.ldst_exc)
+ srr1_i = exc.srr1 # new SRR1 bits come from exception
nia_o = self.o.nia
svsrr0_o, srr0_o, srr1_o = self.o.svsrr0, self.o.srr0, self.o.srr1
- # trap address
+ # trap address, including KAIVB override
comb += nia_o.data.eq(trap_addr)
+ comb += nia_o.data[13:].eq(self.kaivb[13:])
comb += nia_o.ok.eq(1)
# addr to begin from on return
comb += srr0_o.data.eq(return_addr)
comb += srr0_o.ok.eq(1)
- # take a copy of the current MSR into SRR1
- comb += msr_copy(srr1_o.data, msr_i) # old MSR
+ # take a copy of the current MSR into SRR1, but first copy old SRR1
+ # this preserves the bits of SRR1 that are not supposed to change:
+ # MSR.IR,DR,PMM,RI,LE (0-5) and MR,FP,ME,FE0 (11-14)
+ # i would suggest reading v3.0C p1063 Book III section 7.2.1 for
+ # advice but it's so obscure and indirect, that it's just easier
+ # to copy microwatt behaviour. see writeback.vhdl
+ # IMPORTANT: PowerDecoder2 needed to actually read SRR1 for
+ # it to have the contents *of* SRR1 to copy over!
+ comb += msr_copy(srr1_o.data, msr_i, False) # old MSR
+ comb += srr1_o.data[16:22].eq(srr1_i[0:6]) # IR,DR,PMM,RI,LE
+ comb += srr1_o.data[27:31].eq(srr1_i[11:15]) # MR,FP,ME,FE0
comb += srr1_o.ok.eq(1)
# take a copy of the current SVSTATE into SVSRR0
def elaborate(self, platform):
m = Module()
- comb = m.d.comb
+ comb, sync = m.d.comb, m.d.sync
op = self.i.ctx.op
# convenience variables
# TODO: some #defines for the bits n stuff.
with m.Switch(op.insn_type):
+ ##############
+ # KAIVB https://bugs.libre-soc.org/show_bug.cgi?id=859
+
+ with m.Case(MicrOp.OP_MTSPR):
+ sync += self.kaivb.eq(a_i)
+
+ with m.Case(MicrOp.OP_MFSPR):
+ comb += o.data.eq(self.kaivb)
+ comb += o.ok.eq(1)
+
###############
# TDI/TWI/TD/TW. v3.0B p90-91
comb += srr1_o.data[PI.FP].eq(1)
with m.If(traptype & TT.ADDR):
comb += srr1_o.data[PI.ADR].eq(1)
- with m.If(traptype & TT.MEMEXC):
+ with m.If((traptype & TT.MEMEXC).bool() &
+ (trapaddr == 0x400)):
+ # Instruction Storage Interrupt (ISI - 0x400)
+ # v3.0C Book III Chap 7.5.5 p1085
# decode exception bits, store in SRR1
exc = LDSTException("trapexc")
comb += exc.eq(op.ldst_exc)
# hypervisor stuff. here: bits 3 (HV) and 51 (ME) were
# copied over by msr_copy but if HV was not set we need
# the *original* (msr_i) bits
- with m.If(~msr_i[MSR.HV]):
- comb += msr_o.data[MSR.HV].eq(msr_i[MSR.HV])
- comb += msr_o.data[MSR.ME].eq(msr_i[MSR.ME])
+ # XXX taking this out to see what happens when running
+ # linux-5.7 microwatt buildroot. microwatt does not
+ # implement HV, so this is unlikely to work. 0x900
+ # linux kernel exception handling tends to support this
+ # with m.If(~msr_i[MSR.HV]):
+ # comb += msr_o.data[MSR.HV].eq(msr_i[MSR.HV])
+ # comb += msr_o.data[MSR.ME].eq(msr_i[MSR.ME])
comb += msr_o.ok.eq(1)
# MSR was in srr1: copy it over, however *caveats below*
comb += msr_copy(msr_o.data, srr1_i, zero_me=False) # don't zero
- with m.If(~self.i.ctx.op.insn[9]): # XXX BAD HACK! (hrfid)
- with m.If(field(msr_i, 3)): # HV
- comb += field(msr_o, 51).eq(field(srr1_i, 51)) # ME
- with m.Else():
- comb += field(msr_o, 51).eq(field(msr_i, 51)) # ME
+ if False: # XXX no - not doing hypervisor yet
+ with m.If(~self.i.ctx.op.insn[9]): # XXX BAD HACK! (hrfid)
+ with m.If(field(msr_i, 3)): # HV
+ comb += field(msr_o, 51).eq(field(srr1_i, 51)) # ME
+ with m.Else():
+ comb += field(msr_o, 51).eq(field(msr_i, 51)) # ME
+ else:
+ # same as microwatt: treat MSR.ME rfid same as hrfid
+ comb += field(msr_o, 51).eq(field(srr1_i, 51)) # ME
# check problem state: if set, not permitted to set EE,IR,DR
msr_check_pr(m, srr1_i, msr_o.data)
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