RISC-V: Clear mtval/stval on exceptions without info

mtval/stval must be set on all exceptions but zero is
a legal value if there is no exception specific info.
Placing the instruction bytes for illegal instruction
exceptions in mtval/stval is an optional feature and
is currently not supported by QEMU RISC-V.

Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/target/riscv/helper.c b/target/riscv/helper.c
index 02cbcea..95889f2 100644
--- a/target/riscv/helper.c
+++ b/target/riscv/helper.c
@@ -466,6 +466,10 @@ void riscv_cpu_do_interrupt(CPUState *cs)
                     ": badaddr 0x" TARGET_FMT_lx, env->mhartid, env->badaddr);
             }
             env->sbadaddr = env->badaddr;
+        } else {
+            /* otherwise we must clear sbadaddr/stval
+             * todo: support populating stval on illegal instructions */
+            env->sbadaddr = 0;
         }
 
         target_ulong s = env->mstatus;
@@ -487,6 +491,10 @@ void riscv_cpu_do_interrupt(CPUState *cs)
                     ": badaddr 0x" TARGET_FMT_lx, env->mhartid, env->badaddr);
             }
             env->mbadaddr = env->badaddr;
+        } else {
+            /* otherwise we must clear mbadaddr/mtval
+             * todo: support populating mtval on illegal instructions */
+            env->mbadaddr = 0;
         }
 
         target_ulong s = env->mstatus;