Does NaxRiscv update mtval after trap illegal_inst?

[zhangkanqi]

Hi,
It seems NaxRiscv wants to update tval when trapping exception in the source codes.

But I found that when encounters illegal_inst exception under U-mode(the exception is trapped into M-mode), NaxRiscv doesn't update mtval correctly, the value of mtval is still 0x0.

[Dolu1990]

Hi,

I tried to reproduce, but on my side it is fine :

#include "../../driver/privileged.h"
  trap_setup
  machine_to_user
  .word 0xffffffff
  trap_handle
  csrr x1, mtval // => 0xffffffff
  j pass

I would need your exact setup to reproduce.
When using fuzing, i noticed that very often the symptoms detected by the testbench are kinda far apparts from the reason why things are going wrong :)

[zhangkanqi]

Sorry, I will provide all files used for debugging in later issues. I'm a little bit lazy this time hh.
For debug：
update_mtval_incorrect.zip

For reproduce:
NaxRiscv: f335738

cd $NAXRISCV
vim NaxRiscv/src/main/scala/naxriscv/Gen.scala # enable Rvc&float&double in Gen64
sbt "runMain naxriscv.Gen64"
cd $NAXRISCV/src/test/cpp/naxriscv
./obj_dir/VNaxRiscv --load-elf=./input_nax_53.elf --start-symbol=_start --pass-symbol=write_tohost --timeout=100000 --name=input_nax_0 --trace --trace-ref --spike-debug