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 <froy...@codesourcery.com> Signed-off-by: Maciej W. Rozycki <ma...@codesourcery.com> --- Another change that has waited for too long, with the original discussion archived here: http://lists.nongnu.org/archive/html/qemu-devel/2012-06/msg01230.html Resending with what hopefully is a better description and updated to reflect the move of `cpu_io_recompile' from exec.c to translate-all.c. Please apply, Maciej qemu-mips-b16.diff Index: qemu-git-trunk/target-mips/translate.c =================================================================== --- qemu-git-trunk.orig/target-mips/translate.c 2014-11-07 18:34:30.927788566 +0000 +++ qemu-git-trunk/target-mips/translate.c 2014-11-07 18:34:35.428958223 +0000 @@ -19452,7 +19452,8 @@ 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; } Index: qemu-git-trunk/translate-all.c =================================================================== --- qemu-git-trunk.orig/translate-all.c 2014-11-07 17:33:13.037575065 +0000 +++ qemu-git-trunk/translate-all.c 2014-11-07 18:34:35.428958223 +0000 @@ -1534,7 +1534,7 @@ void cpu_io_recompile(CPUState *cpu, uin branch. */ #if defined(TARGET_MIPS) if ((env->hflags & MIPS_HFLAG_BMASK) != 0 && n > 1) { - env->active_tc.PC -= 4; + env->active_tc.PC -= (env->hflags & MIPS_HFLAG_B16 ? 2 : 4); cpu->icount_decr.u16.low++; env->hflags &= ~MIPS_HFLAG_BMASK; }
