7a8722720142f29fdfa02dc37dbb14983e1ffa7f
1 # Proof of correctness for trap pipeline, main stage
6 * https://bugs.libre-soc.org/show_bug.cgi?id=421
7 * https://libre-soc.org/openpower/isa/fixedtrap/
8 * https://libre-soc.org/openpower/isa/sprset/
9 * https://libre-soc.org/openpower/isa/system/
15 from nmigen
import Cat
, Const
, Elaboratable
, Module
, Signal
, signed
16 from nmigen
.asserts
import Assert
, AnyConst
17 from nmigen
.cli
import rtlil
19 from nmutil
.extend
import exts
20 from nmutil
.formaltest
import FHDLTestCase
22 from soc
.consts
import MSR
, MSRb
, PI
, TT
, field
24 from soc
.decoder
.power_enums
import MicrOp
26 from soc
.fu
.trap
.main_stage
import TrapMainStage
27 from soc
.fu
.trap
.pipe_data
import TrapPipeSpec
28 from soc
.fu
.trap
.trap_input_record
import CompTrapOpSubset
31 class Driver(Elaboratable
):
35 def elaborate(self
, platform
):
39 rec
= CompTrapOpSubset()
40 pspec
= TrapPipeSpec(id_wid
=2)
42 m
.submodules
.dut
= dut
= TrapMainStage(pspec
)
44 # frequently used aliases
46 msr_o
, msr_i
= dut
.o
.msr
, op
.msr
47 srr0_o
, srr0_i
= dut
.o
.srr0
, dut
.i
.srr0
48 srr1_o
, srr1_i
= dut
.o
.srr1
, dut
.i
.srr1
53 d_fields
= dut
.fields
.FormD
54 sc_fields
= dut
.fields
.FormSC
57 with m
.Switch(op
.insn_type
):
60 # TDI/TWI/TD/TW. v3.0B p90-91
62 with m
.Case(MicrOp
.OP_TRAP
):
63 to
= Signal(len(d_fields
.TO
))
64 comb
+= to
.eq(d_fields
.TO
[0:-1])
68 comb
+= a_i
.eq(dut
.i
.a
)
69 comb
+= b_i
.eq(dut
.i
.b
)
71 a_s
= Signal(signed(64), reset_less
=True)
72 b_s
= Signal(signed(64), reset_less
=True)
73 a
= Signal(64, reset_less
=True)
74 b
= Signal(64, reset_less
=True)
76 with m
.If(op
.is_32bit
):
77 comb
+= a_s
.eq(exts(a_i
, 32, 64))
78 comb
+= b_s
.eq(exts(b_i
, 32, 64))
79 comb
+= a
.eq(a_i
[0:32])
80 comb
+= b
.eq(b_i
[0:32])
87 lt_s
= Signal(reset_less
=True)
88 gt_s
= Signal(reset_less
=True)
89 lt_u
= Signal(reset_less
=True)
90 gt_u
= Signal(reset_less
=True)
91 equal
= Signal(reset_less
=True)
93 comb
+= lt_s
.eq(a_s
< b_s
)
94 comb
+= gt_s
.eq(a_s
> b_s
)
95 comb
+= lt_u
.eq(a
< b
)
96 comb
+= gt_u
.eq(a
> b
)
97 comb
+= equal
.eq(a
== b
)
99 trapbits
= Signal(5, reset_less
=True)
100 comb
+= trapbits
.eq(Cat(gt_u
, lt_u
, equal
, gt_s
, lt_s
))
103 traptype
= op
.traptype
104 comb
+= take_trap
.eq(traptype
.any() |
(trapbits
& to
).any())
106 with m
.If(take_trap
):
107 expected_msr
= Signal(len(msr_o
.data
))
108 comb
+= expected_msr
.eq(op
.msr
)
110 comb
+= field(expected_msr
, MSRb
.IR
).eq(0)
111 comb
+= field(expected_msr
, MSRb
.DR
).eq(0)
112 comb
+= field(expected_msr
, MSRb
.FE0
).eq(0)
113 comb
+= field(expected_msr
, MSRb
.FE1
).eq(0)
114 comb
+= field(expected_msr
, MSRb
.EE
).eq(0)
115 comb
+= field(expected_msr
, MSRb
.RI
).eq(0)
116 comb
+= field(expected_msr
, MSRb
.SF
).eq(1)
117 comb
+= field(expected_msr
, MSRb
.TM
).eq(0)
118 comb
+= field(expected_msr
, MSRb
.VEC
).eq(0)
119 comb
+= field(expected_msr
, MSRb
.VSX
).eq(0)
120 comb
+= field(expected_msr
, MSRb
.PR
).eq(0)
121 comb
+= field(expected_msr
, MSRb
.FP
).eq(0)
122 comb
+= field(expected_msr
, MSRb
.PMM
).eq(0)
125 # see https://bugs.libre-soc.org/show_bug.cgi?id=325#c120
127 # saf2: no it's not. Proof by substitution:
129 # field(R,MSRb.TEs,MSRb.TEe).eq(0)
130 # == field(R,53,54).eq(0)
131 # == R[field_slice(53,54)].eq(0)
132 # == R[slice(63-54, (63-53)+1)].eq(0)
133 # == R[slice(9, 11)].eq(0)
136 # Also put proof in py-doc for field().
138 comb
+= field(expected_msr
, MSRb
.TEs
, MSRb
.TEe
).eq(0)
140 comb
+= field(expected_msr
, MSRb
.UND
).eq(0)
141 comb
+= field(expected_msr
, MSRb
.LE
).eq(1)
143 expected_srr1
= Signal(len(srr1_o
.data
))
144 comb
+= expected_srr1
.eq(op
.msr
)
146 # Per V3.0B, page 1075
147 comb
+= field(expected_srr1
, 33, 36).eq(0)
148 comb
+= field(expected_srr1
, 42).eq(0) # TM_BAD_THING
149 comb
+= field(expected_srr1
, 43).eq(traptype
[0]) # FP
150 comb
+= field(expected_srr1
, 44).eq(traptype
[4]) # ILLEG
151 comb
+= field(expected_srr1
, 45).eq(traptype
[1]) # PRIV
152 comb
+= field(expected_srr1
, 46).eq(traptype
== 0) # TRAP
153 comb
+= field(expected_srr1
, 47).eq(traptype
[3]) # ADDR
157 Assert(msr_o
.data
== expected_msr
),
159 Assert(srr0_o
.data
== op
.cia
),
161 Assert(srr1_o
.data
== expected_srr1
),
163 Assert(nia_o
.data
== op
.trapaddr
<< 4),
174 with m
.Case(MicrOp
.OP_MFMSR
):
177 Assert(dut
.o
.o
.data
== msr_i
),
183 with m
.Case(MicrOp
.OP_RFID
):
189 # Note: going through the spec pseudo-code, line-by-line,
190 # in order, with these assertions. idea is: compare
191 # *directly* against the pseudo-code. therefore, leave
192 # numbering in (from pseudo-code) and add *comments* about
193 # which field it is (3 == HV etc.)
195 # spec: MSR[51] <- (MSR[3] & SRR1[51]) | ((¬MSR[3] & MSR[51]))
196 with m
.If(field(msr_i
, 3)): # HV
197 comb
+= Assert(field(msr_o
, 51) == field(srr1_i
, 51)) # ME
199 comb
+= Assert(field(msr_o
, 51) == field(msr_i
, 51)) # ME
201 # if (MSR[29:31] != 0b010) | (SRR1[29:31] != 0b000) then
202 # MSR[29:31] <- SRR1[29:31]
203 with m
.If((field(msr_i
, 29, 31) != 0b010) |
204 (field(srr1_i
, 29, 31) != 0b000)):
205 comb
+= Assert(field(msr_o
.data
, 29, 31) ==
206 field(srr1_i
, 29, 31))
208 comb
+= Assert(field(msr_o
.data
, 29, 31) ==
209 field(msr_i
, 29, 31))
211 # check EE (48) IR (58), DR (59): PR (49) will over-ride
215 field(srr1_i
, 48) |
field(srr1_i
, 49)
219 field(srr1_i
, 58) |
field(srr1_i
, 49)
223 field(srr1_i
, 59) |
field(srr1_i
, 49)
227 # remaining bits: straight copy. don't know what these are:
228 # just trust the v3.0B spec is correct.
230 Assert(field(msr_o
, 0, 2) == field(srr1_i
, 0, 2)),
231 Assert(field(msr_o
, 4, 28) == field(srr1_i
, 4, 28)),
232 Assert(field(msr_o
, 32) == field(srr1_i
, 32)),
233 Assert(field(msr_o
, 37, 41) == field(srr1_i
, 37, 41)),
234 Assert(field(msr_o
, 49, 50) == field(srr1_i
, 49, 50)),
235 Assert(field(msr_o
, 52, 57) == field(srr1_i
, 52, 57)),
236 Assert(field(msr_o
, 60, 63) == field(srr1_i
, 60, 63)),
239 # check NIA against SRR0. 2 LSBs are set to zero (word-align)
240 comb
+= Assert(nia_o
.data
== Cat(Const(0, 2), dut
.i
.srr0
[2:]))
245 with m
.Case(MicrOp
.OP_SC
):
246 expected_msr
= Signal(len(msr_o
.data
))
247 comb
+= expected_msr
.eq(op
.msr
)
248 # Unless otherwise documented, these exceptions to the MSR bits
249 # are documented in Power ISA V3.0B, page 1063 or 1064.
250 # We are not supporting hypervisor or transactional semantics,
251 # so we skip enforcing those fields' properties.
252 comb
+= field(expected_msr
, MSRb
.IR
).eq(0)
253 comb
+= field(expected_msr
, MSRb
.DR
).eq(0)
254 comb
+= field(expected_msr
, MSRb
.FE0
).eq(0)
255 comb
+= field(expected_msr
, MSRb
.FE1
).eq(0)
256 comb
+= field(expected_msr
, MSRb
.EE
).eq(0)
257 comb
+= field(expected_msr
, MSRb
.RI
).eq(0)
258 comb
+= field(expected_msr
, MSRb
.SF
).eq(1)
259 comb
+= field(expected_msr
, MSRb
.TM
).eq(0)
260 comb
+= field(expected_msr
, MSRb
.VEC
).eq(0)
261 comb
+= field(expected_msr
, MSRb
.VSX
).eq(0)
262 comb
+= field(expected_msr
, MSRb
.PR
).eq(0)
263 comb
+= field(expected_msr
, MSRb
.FP
).eq(0)
264 comb
+= field(expected_msr
, MSRb
.PMM
).eq(0)
265 comb
+= field(expected_msr
, MSRb
.TEs
, MSRb
.TEe
).eq(0)
266 comb
+= field(expected_msr
, MSRb
.UND
).eq(0)
267 comb
+= field(expected_msr
, MSRb
.LE
).eq(1)
270 Assert(dut
.o
.srr0
.ok
),
274 Assert(dut
.o
.srr0
.data
== (op
.cia
+ 4)[0:64]),
275 Assert(field(srr1_o
, 33, 36) == 0),
276 Assert(field(srr1_o
, 42, 47) == 0),
277 Assert(field(srr1_o
, 0, 32) == field(msr_i
, 0, 32)),
278 Assert(field(srr1_o
, 37, 41) == field(msr_i
, 37, 41)),
279 Assert(field(srr1_o
, 48, 63) == field(msr_i
, 48, 63)),
281 Assert(msr_o
.data
== expected_msr
),
284 comb
+= dut
.i
.ctx
.matches(dut
.o
.ctx
)
289 class TrapMainStageTestCase(FHDLTestCase
):
290 def test_formal(self
):
291 self
.assertFormal(Driver(), mode
="bmc", depth
=10)
292 self
.assertFormal(Driver(), mode
="cover", depth
=10)
294 def test_ilang(self
):
295 vl
= rtlil
.convert(Driver(), ports
=[])
296 with
open("trap_main_stage.il", "w") as f
:
300 if __name__
== '__main__':