Re: [PATCH] tcg/aarch64: Fix illegal insn from out-of-range shli

[Joel Stanley]

On Thu, 2 Jun 2022 at 01:17, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> The masking in tcg_out_shl was incorrect, producing an
> illegal instruction, rather than merely unspecified results
> for the out-of-range shift.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1051
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

I can confirm this fixes the issue I reported, thanks Richard.

Tested-by: Joel Stanley <joel@jms.id.au>

> ---
>  tcg/aarch64/tcg-target.c.inc | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tcg/aarch64/tcg-target.c.inc b/tcg/aarch64/tcg-target.c.inc
> index 61e284bb5c..d997f7922a 100644
> --- a/tcg/aarch64/tcg-target.c.inc
> +++ b/tcg/aarch64/tcg-target.c.inc
> @@ -1261,7 +1261,7 @@ static inline void tcg_out_shl(TCGContext *s, TCGType 
> ext,
>  {
>      int bits = ext ? 64 : 32;
>      int max = bits - 1;
> -    tcg_out_ubfm(s, ext, rd, rn, bits - (m & max), max - (m & max));
> +    tcg_out_ubfm(s, ext, rd, rn, (bits - m) & max, (max - m) & max);
>  }
>
>  static inline void tcg_out_shr(TCGContext *s, TCGType ext,
> --
> 2.34.1
>
>