linux-kernel - Re: [RFC GIT PULL] softirq: Consolidation and stack overrun fix

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Message-ID: <1379824861.24090.12.camel@pasglop>
Date:	Sun, 22 Sep 2013 14:41:01 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@....ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	James Hogan <james.hogan@...tec.com>,
	"James E.J. Bottomley" <jejb@...isc-linux.org>,
	Helge Deller <deller@....de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC GIT PULL] softirq: Consolidation and stack overrun fix

On Sun, 2013-09-22 at 14:39 +1000, Benjamin Herrenschmidt wrote:
> How do you do your per-cpu on x86 ? On powerpc we struggle because we
> try to dedicate a register (r13) to this PACA (the per-cpu offset hangs
> off it), but we constantly run into issues where gcc copies r13 to
> another register and then indexes off that, even accross
> preempt_enable/disable sections, or worst such as saving/restoring from
> the stack. We can't seem to get the compiler to treat it appropriately
> as volatile.

Also, do you have a half-decent way of getting to per-cpu from asm ?

Cheers,
Ben.


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