From: Ralf Baechle <ralf@linux-mips.org>
To: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: linux-mips@linux-mips.org
Subject: Re: [PATCH] mips/mm: fix module support on SiByte
Date: Mon, 22 Mar 2010 15:59:18 +0100 [thread overview]
Message-ID: <20100322145918.GR4554@linux-mips.org> (raw)
In-Reply-To: <20100321110241.GA25569@Chamillionaire.breakpoint.cc>
On Sun, Mar 21, 2010 at 12:02:41PM +0100, Sebastian Andrzej Siewior wrote:
> Since commit 656be92f aka "Load modules to CKSEG0 if
> CONFIG_BUILD_ELF64=n" module support is broken on 64bit. Since then
> modules arr loaded into 32bit compat adresses which are sign extended
> 64bit addresses. The SiByte war handler was not updated and those
> addresses were not recognized by the TLB hadling.
> This patch fixes this by shifting away the upper bits including the R
> and Fill bits. Now we compare VPN2 of C0_ENTRYHI against the matching
> bits at C0_BADVADDR.
Good detective work but I'll check against the errata documents (which
are non-public, sigh ...) before applying your patch.
The M3 workaround in which you found this bug is currently applied to all
Sibyte SB1 cores while probably only a relativly small number of the cores
in circulation are affected so we should refine the workaround to be only
applied if the System Revision Register indicates a system older than
revision C0. This could get rid of 6 instructions which according to the
usual rule of thumb would result in a speedup of ~ 3%.
Ralf
next prev parent reply other threads:[~2010-03-22 14:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-21 11:02 [PATCH] mips/mm: fix module support on SiByte Sebastian Andrzej Siewior
2010-03-22 14:59 ` Ralf Baechle [this message]
2010-03-22 18:09 ` Ralf Baechle
2010-03-23 1:04 ` Ralf Baechle
2010-03-23 23:31 ` Ralf Baechle
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