[otbn,dv] Alter ISS to match RTL for BN.MOVR double errors
This is the same logic as the previous commit: we can underflow the
call stack with one operand but still have a valid (but illegal) value
in the other operand. Handle this more symmetrically, which also
matches the behaviour of the RTL.
Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>
diff --git a/hw/ip/otbn/dv/otbnsim/sim/insn.py b/hw/ip/otbn/dv/otbnsim/sim/insn.py
index 6f2d045..a4fe726 100644
--- a/hw/ip/otbn/dv/otbnsim/sim/insn.py
+++ b/hw/ip/otbn/dv/otbnsim/sim/insn.py
@@ -1156,28 +1156,40 @@
grd_val = state.gprs.get_reg(self.grd).read_unsigned()
grs_val = state.gprs.get_reg(self.grs).read_unsigned()
+
+ bad_grs = state.gprs.call_stack_err and (self.grs == 1)
+ bad_grd = state.gprs.call_stack_err and (self.grd == 1)
+
+ saw_err = False
+
if state.gprs.call_stack_err:
state.stop_at_end_of_cycle(ErrBits.CALL_STACK)
+ saw_err = True
+
+ if grd_val > 31 and not bad_grd:
+ state.stop_at_end_of_cycle(ErrBits.ILLEGAL_INSN)
+ saw_err = True
+
+ if grs_val > 31 and not bad_grs:
+ state.stop_at_end_of_cycle(ErrBits.ILLEGAL_INSN)
+ saw_err = True
+
+ if saw_err:
return
- if grd_val > 31:
- state.stop_at_end_of_cycle(ErrBits.ILLEGAL_INSN)
- elif grs_val > 31:
- state.stop_at_end_of_cycle(ErrBits.ILLEGAL_INSN)
- else:
- wrd = grd_val & 0x1f
- wrs = grs_val & 0x1f
+ wrd = grd_val & 0x1f
+ wrs = grs_val & 0x1f
- value = state.wdrs.get_reg(wrs).read_unsigned()
- state.wdrs.get_reg(wrd).write_unsigned(value)
+ value = state.wdrs.get_reg(wrs).read_unsigned()
+ state.wdrs.get_reg(wrd).write_unsigned(value)
- if self.grd_inc:
- new_grd_val = grd_val + 1
- state.gprs.get_reg(self.grd).write_unsigned(new_grd_val)
+ if self.grd_inc:
+ new_grd_val = grd_val + 1
+ state.gprs.get_reg(self.grd).write_unsigned(new_grd_val)
- if self.grs_inc:
- new_grs_val = grs_val + 1
- state.gprs.get_reg(self.grs).write_unsigned(new_grs_val)
+ if self.grs_inc:
+ new_grs_val = grs_val + 1
+ state.gprs.get_reg(self.grs).write_unsigned(new_grs_val)
class BNWSRR(OTBNInsn):
diff --git a/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-1.exp b/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-1.exp
index f0f4388..6044f56 100644
--- a/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-1.exp
+++ b/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-1.exp
@@ -5,4 +5,4 @@
x2 = 100
INSN_CNT = 1
-ERR_BITS = 0x4 # CALL_STACK
+ERR_BITS = 0xc # CALL_STACK, ILLEGAL_INSN
diff --git a/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-2.exp b/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-2.exp
index f0f4388..6044f56 100644
--- a/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-2.exp
+++ b/hw/ip/otbn/dv/otbnsim/test/simple/multi/bnmovr-2.exp
@@ -5,4 +5,4 @@
x2 = 100
INSN_CNT = 1
-ERR_BITS = 0x4 # CALL_STACK
+ERR_BITS = 0xc # CALL_STACK, ILLEGAL_INSN
