Re: [Qemu-arm] [Qemu-devel] [PATCH] translate.c: Fix usermode big-endian AArch32 LDREXD and STREXD

[Richard Henderson]

On 10/21/2017 03:17 AM, Peter Maydell wrote:
>>> -        gen_aa32_frob64(s, o64);
>>> +        if (s->be_data) {
>>> +            tcg_gen_rotri_i64(o64, o64, 32);
>>> +        }
>>>          tcg_gen_setcond_i64(TCG_COND_NE, o64, o64, cpu_exclusive_val);
>>
>> We're not splitting o64 to parts.  Are you sure it shouldn't stay as frob?
> 
> This is confusing, but I don't think frob is right. We want to
> be matching either (a) the transformation we just did to produce
> the 64 bit data we're storing, or (b) the transformation we
> do on the ldrexd, don't we? Neither of those is frob.
> 
> I think I need to think through a bit more carefully about
> what's actually going on here, since we seem to have the
> value in two places (actual memory, and the cpu_exclusive_val
> TCGv.)

We should match what we do in ldrexd, I think.  Which is just a straight BE
load.  So I guess the frob64 should be dropped and nothing should replace it.


r~