linux-kernel - Re: [PATCH] MIPS: Kernel hangs occasionally during boot.

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]

Date:	Wed, 9 Nov 2011 10:34:33 +0000
From:	Ralf Baechle <ralf@...ux-mips.org>
To:	"Gleb O. Raiko" <raiko@...si.msk.ru>
Cc:	Al Cooper <alcooperx@...il.com>, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Kernel hangs occasionally during boot.

On Wed, Nov 09, 2011 at 11:40:21AM +0400, Gleb O. Raiko wrote:

> On 08.11.2011 21:55, Ralf Baechle wrote:
> >but we may need another hazard barrier to
> >replace back_to_back_c0_hazard().
> Urgently. We need some ticks to wait until counter state machine has
> been updated. The amount of ticks may occasionally be the same as in
> case of back_to_back_hazard for some cpus. It's completely different
> for others, I sure. Original compare_change_hazard waits up to 12
> ticks for r4k. While I don't think this amount should depend on
> irq_disable_hazard as old code assumes, we may still need 12 or so
> ticks for old cpus.

Hmm...  Looking at the R4000 manual which generall has the longest
pipeline hazards, mtc0 gets executed at stage 7, interrupts get sampled
at stage 3 meaning there is a (7 - 3 - 1) = 3 cycles hazard.  Does
that one statisfy your constraints?  Or are additional cycles needed
for a hazard that's generated outside of the CPU's pipeline?

  Ralf
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/