linux-kernel - Re: [RFC PATCH for 5.2 10/10] rseq/selftests: mips: use break instruction for RSEQ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190424231717.os4p6fq7fbx6afxa@pburton-laptop>
Date:   Wed, 24 Apr 2019 23:17:18 +0000
From:   Paul Burton <paul.burton@...s.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-api <linux-api@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <andi@...stfloor.org>,
        Chris Lameter <cl@...ux.com>, Ben Maurer <bmaurer@...com>,
        rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Joel Fernandes <joelaf@...gle.com>, shuah <shuah@...nel.org>,
        James Hogan <jhogan@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        linux-mips <linux-mips@...ux-mips.org>
Subject: Re: [RFC PATCH for 5.2 10/10] rseq/selftests: mips: use break
 instruction for RSEQ_SIG

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