Re: [Qemu-devel] [PATCH v1 10/17] target-arm: implement setend

[Peter Maydell <peter.maydell@linaro.org>]

On 18 January 2016 at 07:12, Peter Crosthwaite
<crosthwaitepeter@gmail.com> wrote:
> From: Paolo Bonzini <pbonzini@redhat.com>
>
> Since this is not a high-performance path, just use a helper to
> flip the E bit and force a lookup in the hash table since the
> flags have changed.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
> ---
>
>  target-arm/helper.h    |  1 +
>  target-arm/op_helper.c |  5 +++++
>  target-arm/translate.c | 16 ++++++++--------
>  3 files changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/target-arm/helper.h b/target-arm/helper.h
> index c2a85c7..2315a9c 100644
> --- a/target-arm/helper.h
> +++ b/target-arm/helper.h
> @@ -48,6 +48,7 @@ DEF_HELPER_FLAGS_3(sel_flags, TCG_CALL_NO_RWG_SE,
>                     i32, i32, i32, i32)
>  DEF_HELPER_2(exception_internal, void, env, i32)
>  DEF_HELPER_4(exception_with_syndrome, void, env, i32, i32, i32)
> +DEF_HELPER_1(setend, void, env)
>  DEF_HELPER_1(wfi, void, env)
>  DEF_HELPER_1(wfe, void, env)
>  DEF_HELPER_1(yield, void, env)
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index e42d287..2a4bc67 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -295,6 +295,11 @@ uint32_t HELPER(usat16)(CPUARMState *env, uint32_t x, uint32_t shift)
>      return res;
>  }
>
> +void HELPER(setend)(CPUARMState *env)
> +{
> +    env->uncached_cpsr ^= CPSR_E;
> +}
> +
>  /* Function checks whether WFx (WFI/WFE) instructions are set up to be trapped.
>   * The function returns the target EL (1-3) if the instruction is to be trapped;
>   * otherwise it returns 0 indicating it is not trapped.
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index cb925ef..192a5d6 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -7726,10 +7726,10 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
>          if ((insn & 0x0ffffdff) == 0x01010000) {
>              ARCH(6);
>              /* setend */
> -            if (((insn >> 9) & 1) != s->bswap_code) {
> -                /* Dynamic endianness switching not implemented. */
> -                qemu_log_mask(LOG_UNIMP, "arm: unimplemented setend\n");
> -                goto illegal_op;
> +            if (((insn >> 9) & 1) != !!(s->mo_endianness == MO_BE)) {
> +                gen_helper_setend(cpu_env);
> +                gen_set_pc_im(s, s->pc);
> +                s->is_jmp = DISAS_JUMP;

Rather than manually calling set_pc_im and using DISAS_JUMP, better
to use DISAS_UPDATE, which will do the gen_set_pc_im() call for you.

(Ditto in the other hunk.)

thanks
-- PMM