Re: [RFC PATCH for 5.2 10/10] rseq/selftests: mips: use break instruction for RSEQ_SIG

Paul Burton <[email protected]> Wed, 24 Apr 2019 23:17:18 +0000
Newsgroups gmane.linux.kernel,gmane.linux.kernel.api,gmane.linux.ports.mips.general
Message-ID <20190424231717.os4p6fq7fbx6afxa@pburton-laptop>
Hi Mathieu,

On Wed, Apr 24, 2019 at 07:12:03PM -0400, Mathieu Desnoyers wrote:
> Does the following comment above the forest of #ifdef work for you ?
> 
> /*
>  * RSEQ_SIG uses the break instruction. The instruction pattern is:
>  *
>  * On MIPS:
>  *      0350000d        break     0x350
>  *
>  * On nanoMIPS32:
>  *      00100350        break     0x350
>  *
>  * On microMIPS:
>  *      0000d407        break     0x350
>  *
>  * For nanoMIPS32 and microMIPS, the instruction stream is encoded as 16-bit
>  * halfwords, so the signature halfwords need to be swapped accordingly for
>  * little-endian.
>  */

I'd probably just say nanoMIPS rather than nanoMIPS32, because when we
get nanoMIPS64 in the future it'll be a superset of nanoMIPS32 & the
break encoding will be the same.

But otherwise it looks good to me :)

Thanks,
    Paul