Re: [PATCH 2/5] target/arm: MTE user mode disassembly

[Richard Henderson <richard.henderson@linaro.org>]

On 3/13/20 7:00 AM, Rémi Denis-Courmont wrote:
> +/* Extract an Allocation Tag from an address */
> +static void gen_extract_tag(TCGv_i64 dest, TCGv_i64 source)
> +{
> +    TCGv_i64 sign = tcg_temp_new_i64();
> +
> +    /* See ARMv8.5-A AllocationTagFromAddress pseudocode */
> +    tcg_gen_extract_i64(sign, source, 55, 1);
> +    tcg_gen_extract_i64(dest, source, 56, 4);
> +    tcg_gen_add_i64(dest, dest, sign);
> +    tcg_gen_andi_i64(dest, dest, 0xf);
> +    tcg_temp_free_i64(sign);
> +}

In addition to everything else, I see that you're working from quite an old
beta version of the memtag spec.

Please grab the most recent Arm ARM, F.a:
https://developer.arm.com/docs/ddi0487/latest

The current version does not really distinguish between logical and physical
tags, so there is no add:

bits(4) AArch64.AllocationTagFromAddress(bits(64) tagged_address)
    return tagged_address<59:56>;


r~