target-mips: Correct MIPS16/microMIPS branch size calculation

Correct MIPS16/microMIPS branch size calculation in PC adjustment
needed:

- to set the value of CP0.ErrorEPC at the entry to the reset exception,

- for the purpose of branch reexecution in the context of device I/O.

Follow the approach taken in `exception_resume_pc' for ordinary, Debug
and NMI exceptions.

MIPS16 and microMIPS branches can be 2 or 4 bytes in size and that has
to be reflected in calculation.  Original MIPS ISA branches, which is
where this code originates from, are always 4 bytes long, just as all
original MIPS ISA instructions.

Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/target-mips/translate.c b/target-mips/translate.c
index a5a5ca44ee..b5d5b39092 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -19439,7 +19439,8 @@ void cpu_state_reset(CPUMIPSState *env)
     if (env->hflags & MIPS_HFLAG_BMASK) {
         /* If the exception was raised from a delay slot,
            come back to the jump.  */
-        env->CP0_ErrorEPC = env->active_tc.PC - 4;
+        env->CP0_ErrorEPC = (env->active_tc.PC
+                             - (env->hflags & MIPS_HFLAG_B16 ? 2 : 4));
     } else {
         env->CP0_ErrorEPC = env->active_tc.PC;
     }