From: David Laight <David.Laight@ACULAB.COM>
To: "'Christophe Leroy'" <christophe.leroy@c-s.fr>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
"Michael Ellerman" <mpe@ellerman.id.au>,
Scott Wood <oss@buserror.net>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] powerpc/32: Move entry_32 functions just after HEAD functions.
Date: Wed, 19 Apr 2017 15:16:33 +0000 [thread overview]
Message-ID: <063D6719AE5E284EB5DD2968C1650D6DCFFD56A5@AcuExch.aculab.com> (raw)
In-Reply-To: <20170418070126.A18EF67952@localhost.localdomain>
From: Christophe Leroy
> By default, PPC8xx PINs an ITLB on the first 8M of memory in order
> to avoid any ITLB miss on kernel code.
> However, with some debug functions like DEBUG_PAGEALLOC and
> (soon to come) DEBUG_RODATA, the PINned TLB is invalidated soon
> after startup so ITLB missed start to happen also on the kernel code.
>
> In order to avoid any ITLB miss in a critical section, we have to
> ensure that their is no page boundary crossed between the setup of
> a new value in SRR0/SRR1 and the associated RFI. This cannot be done
> easily if entry_32 functions sits in the middle of other .text
> functions. By placing entry_32 just after the .head section (as already
> done for entry_64 on PPC64), we can more easily ensure the issue
> doesn't happen.
Shouldn't this be done by putting all the functions that 'matter'
into a named section instead of relying on the order of the input files?
(Which is what I think this is doing.)
David
next prev parent reply other threads:[~2017-04-19 15:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-18 7:01 [PATCH] powerpc/32: Move entry_32 functions just after HEAD functions Christophe Leroy
2017-04-19 15:16 ` David Laight [this message]
2017-04-20 11:25 ` Michael Ellerman
2017-04-20 11:43 ` Christophe LEROY
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