Re: [Qemu-devel] [PATCH 3/7] target/arm/translate-a64: Don't underdecode SIMD ld/st multiple

[Laurent Desnogues <laurent.desnogues@gmail.com>]

On Fri, Jan 25, 2019 at 7:26 PM Peter Maydell <peter.maydell@linaro.org> wrote:
>
> In the AdvSIMD load/store multiple structures encodings,
> the non-post-indexed case should have zeroes in [20:16]
> (which is the Rm field for the post-indexed case).
> Correctly UNDEF the currently unallocated encodings which
> have non-zeroes in those bits.
>
> Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Laurent Desnogues <laurent.desnogues@gmail.com>

Thanks,

Laurent

> ---
>  target/arm/translate-a64.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
> index 8e081758e03..c1f0cad7691 100644
> --- a/target/arm/translate-a64.c
> +++ b/target/arm/translate-a64.c
> @@ -3249,6 +3249,7 @@ static void disas_ldst_multiple_struct(DisasContext *s, uint32_t insn)
>  {
>      int rt = extract32(insn, 0, 5);
>      int rn = extract32(insn, 5, 5);
> +    int rm = extract32(insn, 16, 5);
>      int size = extract32(insn, 10, 2);
>      int opcode = extract32(insn, 12, 4);
>      bool is_store = !extract32(insn, 22, 1);
> @@ -3268,6 +3269,11 @@ static void disas_ldst_multiple_struct(DisasContext *s, uint32_t insn)
>          return;
>      }
>
> +    if (!is_postidx && rm != 0) {
> +        unallocated_encoding(s);
> +        return;
> +    }
> +
>      /* From the shared decode logic */
>      switch (opcode) {
>      case 0x0:
> @@ -3367,7 +3373,6 @@ static void disas_ldst_multiple_struct(DisasContext *s, uint32_t insn)
>      }
>
>      if (is_postidx) {
> -        int rm = extract32(insn, 16, 5);
>          if (rm == 31) {
>              tcg_gen_mov_i64(tcg_rn, tcg_addr);
>          } else {
> --
> 2.20.1
>